The Future Photonics Hub Annual Report 2018

Advancing the manufacturing of next-generation light technologies

Annual Report 2018 A future manufacturing research hub

Contents 3 Introducing the Future Photonics Hub 4 Executive summary 6 The ultimate enabling technology 8 Our four core Technology Platforms and Grand Challenge - High-Performance Silica Optical Fibres - Light Generation and Delivery - Silicon Photonics - Large-Scale Manufacture of Metamaterials and 2D Materials - Integration 28 Building agile capability 30 Making a positive contribution to the UK economy 32 Industrial engagement 34 Progress in promoting photonics 36 Photonics for the next generation 38 The Future Photonics Hub team 39 Industry partners

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Introducing the Future Photonics Hub

The Future Photonics Hub is a partnership between two leading UK research institutes, the Optoelectronics Research Centre (ORC) at the University of Southampton and the EPSRC National Epitaxy Facility at the University of Sheffield.

We work with a network of over 40 companies, representing strategic UK industries ranging from photonics to sectors enabled by photonics, such as telecommunications, healthcare, defence and aerospace.

Together, our combined expertise and facilities enable us to pursue integrated photonics manufacturing across an unprecedented range of platform technologies hitherto disconnected: optical fibres, III-V semiconductors, silicon, metamaterials and 2D materials.

The Hub supports the rapid commercialisation of innovative emerging technologies by: 1. Leading research in four core photonics Technology Platforms 2. Tackling the Grand Challenge of Integration 3. Collaborating on specific industry-defined projects 4. Stimulating industry-driven manufacturing research through a regular Innovation Fund call

Vision Our primary objective is to transfer new, practical and commercial process technologies to industry, to accelerate the growth of the UK’s £12 billion photonics sector and support the £600 billion of UK manufacturing output that depends on this key enabling technology.

The Hub is bridging the gap between academic research and product development, uniting the UK’s excellent science base with companies, R&D organisations and national funding agencies. Together, we are co-investing in developing a pathway to manufacture for the next generation of photonics technologies.

Through our Hub, research is responding to the needs of industry to create new photonics materials, devices and components with ease of integration and production at their core. These transformational technologies will enable the UK to maintain a position of leadership in the high-value global photonics market, driving inward investment through innovation.

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Executive summary

We have made great strides in bringing together the photonics community across the UK and beyond, and in maximising the impact of Government investment.

Since its launch on 1 January 2016, the Future Photonics Hub has tripled the impact of its initial Government investment. By working on over 55 projects to help bring new photonics technologies to market, the Hub has generated in excess of £11 million income from industry, and competitively won a further £10 million in research funding.

Our research across four key Technology Platforms is responding to specific industry needs and important outcomes continue to unfold.

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In 2018, we have…

Achieved interconnection losses of below 0.4 dB between SMF-28 and hollow-core photonic bandgap fibres, with < 30dB back-reflectivity.

Demonstrated quantum dots on indium phosphide substrates with emission wavelengths out to 2.1μm, significant for laser applications in both standard long-haul telecommunications infrastructure and new bandwidths.

Distributed our novel 2D materials to ten international industrial and academic collaborators through formal material transfer agreements.

Achieved record output power and slope efficiency for a 2 μm laser, using custom-made germanate optical fibre and designed for ultra-compact optical amplifier applications.

Reported carrier depletionbased modulators in silicon operating at 20 Gbits/s in the 2 μm wavelength, an order of magnitude improvement on the previous state-of-the-art result from IBM.

Completed a core set of passive devices which we will use to enable integrated photonics circuits.

Successfully generated picosecond optical ‘dark pulses’ using a novel fullyfiberised and packaged metadevice for all-optical signal modulation.

Developed the ability to arc-fusion splice multicore optical fibres with up to 32 cores, achieving < 0.5 dB splice loss for each individual core.

“We know from experience the astonishing range of innovative ideas that emerge when scientists and engineers come together to think about manufacturing, and that scientific discovery is only ever a part of the solution.

“For this reason, at the forefront of our agenda are the key questions: why are we doing this, where is it leading, and what can we do for UK industry?”

Professor Sir David Payne Director, The Future Photonics Hub Director, The Optoelectronics Research Centre, University of Southampton

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The ultimate enabling technology

Photonics, the science and technology of light, has limitless applications that affect nearly every aspect of our lives. From critical components inside our mobile phones, to the physical infrastructure powering the internet and industrial lasers used in manufacturing â&#x20AC;&#x201C; simply stated, photonics is everywhere.

Enabling key industry sectors These are just a few examples of the broad applications of photonics technologies:

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Harsh environment sensors for oil & gas

LIDAR for autonomous vehicles

Silicon photonics for data centres

Laser-written diagnostics for healthcare

Integrated photonics for quantum technology

Sensors for security

Head-up displays for aviation

High power fibre lasers for manufacturing

Optical fibres for high bandwidth telecommunications

Economic growth potential The ubiquity and transformative nature of photonics technologies offers huge potential to stimulate innovation and economic growth.

Consequently, the UK’s internationally-renowned research base, spanning all aspects of photonics, has given rise to a globally significant industry which continues to expand at an impressive rate.

UK photonics manufacturing industry

Value An industry worth

£12.9 bn to the UK economy and growing at

>5% annually

Employment

Output

65,000 1500

Productivity

£62k

people employed in

gross value added per employee,

3x

companies

average productivity

>75% of output exported

Source: The Knowledge Transfer Network (KTN) and Photonics Leadership Group (PLG), June 2017.

The current level of growth in photonics manufacturing and photonics-enabled industries makes now the prime time to focus on making next-generation light technologies easier to produce and embed into products and systems.

Our research in photonics manufacturing and integration at this critical stage will help ensure that the UK secures a significant competitive advantage in a global industry estimated to be worth some £400 billion.

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Our four core Technology Platforms

Our research targets both new, emerging photonics technologies, which stand to have the greatest impact on industry, and those long-standing manufacturing challenges which have so far hindered large-scale industrial uptake.

Our principal aim is to develop the important ‘Pervasive Technologies’ identified in the UK Foresight report on the future of manufacturing1, through carrying out research into four, carefully selected, core Technology Platforms: High-Performance Silica Optical Fibres, Light Generation and Delivery, Silicon Photonics and the Large-Scale Manufacture of Metamaterials and 2D Materials.

In addition, we know that integration is the key to producing low-cost components and systems. Optical fibres, planar waveguide technologies, metamaterials and III-V semiconductors cannot yet be combined in a costefficient integrated manufacturing process.

In direct consultation with over 40 companies, Catapults and Innovative Manufacturing Centres, we have identified a clear business need to reduce the complexity of incorporating next-generation photonics into high-value systems.

Achieving integration is therefore our ‘Grand Challenge’ and we aim to deliver solutions to this industry-wide issue.

Our leading research capabilities The Hub is built on a unique partnership between the Optoelectronics Research Centre (ORC) at the University of Southampton, and the EPSRC National Epitaxy Facility at the University of Sheffield. This collaboration of two leading research institutes ensures that all of our work is founded on scientific excellence and innovation. Here are just some examples of our extensive, combined track record in research and enterprise: n Our

innovations navigate airliners, cut steel, mark iPads, manufacture life-saving medical devices and power the internet.

n Our

optical fibres, invented and made in Southampton, are on the Moon, Mars and the International Space Station.

n Our

epitaxial wafers and devices, produced in Sheffield, have enabled world-class semiconductor research in the UK since 1979.

n Our

combined portfolio of start-ups now exceeds 12 companies.

n Our

expertise is underpinned by over £200 million of state-of-the-art fabrication facilities.

1. Foresight (2013). ‘The Future of Manufacturing: A new era of opportunity and challenge for the UK Project Report’.

Ref: BIS/13/809. The Government Office for Science, London.

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Core Technology Platforms

High-Performance Silica Optical Fibres

Light Generation and Delivery

Optical fibres are essential components in many photonic devices and systems â&#x20AC;&#x201C; from the ready transmission and amplification of light to massively-high power levels. The key challenge in manufacturing fibre is improving its loss, gain and power handling characteristics.

User-driven manufacturing processes will increase the integration and unification of diverse manufacturing platforms in III-V epitaxy, metamaterials, Si-SOI fabrication methods and functional fibre geometries.

Silicon Photonics Achieving integration with optical fibres, light-sources and key processes of wafer-level manufacturing to enable devices such as low-cost transceivers for data centres and mid-infrared sensors.

Large-Scale Manufacture of Metamaterials and 2D Materials Developing costeffective, reliable and volume-scalable methods to fabricate these novel materials in order to enable their practical exploitation in applications such as telecommunications, displays and sensors.

Grand Challenge: Integration The drive to achieve integration is the dominant theme uniting the worldâ&#x20AC;&#x2122;s photonics industries. The photonics industry today can be likened to the early days of electronics when individual components were wired together, resulting in inevitable cost and scaling implications. Todayâ&#x20AC;&#x2122;s photonics components are not yet compatible with a single manufacturing platform and this represents a major industrial challenge.

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Platform performance report: High-Performance Silica Optical Fibres

Novel forms of interconnection and device integration for emerging multi- and hollow-core fibres Challenge To develop a novel means of interconnecting new fibre types emerging from the Future Photonics Hub, to other fibres and/or to other functional components.

Progress Our research has focused on the interconnection of two main fibre types: multi-core optical fibres (MCFs), which incorporate many spatial paths within the fibre cross-section (both N x isolated single mode cores and N x isolated cores), and hollow-core photonic bandgap fibres (HC-PBGFs).

Multicore optical fibres We have developed the ability to arc-fusion splice MCFs with up to 32 cores, achieving < 0.5 dB splice loss for each individual core through the use of fibre end-view alignment and a fibre rotation capability within the splicer. Similar results have been achieved with multi-core few mode fibres (e.g. seven cores x six modes).

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Additionally, we have developed a micro-collimator-based means of interconnecting MCFs with an air gap between the two fibres. Functional components such as filters and isolators can then be inserted into this gap to operate simultaneously on each individual core in order to realise a diversity of MCF devices. Examples of the packaged components that we have developed include a seven core by six mode isolator and a narrow-band filter.

We are currently building high channel count MCF amplifiers, incorporating rare-earth-doped fibres and components made within the Hub. Our aim for early 2019 is to undertake data transmission experiments with an industrial partner.

Hollow-core photonic bandgap fibres Working with collaborators at the Czech Technical University in Prague, we have focused on low temperature gluing-based interconnection approaches.

These have entailed gluing the fibres set to be joined into precision V-grooves, typically one HC-PBCF and a mode-matched solid fibre spliced to a length of conventional SMF 28 fibre. The V-grooves are then precision-aligned and glued together to provide a fibre-to-fibre interconnection. This technique avoids any distortion of the microstructured core region associated with melting during arc-fusion splicing, thereby improving throughput loss. Moreover, an anti-reflection coating can be applied to the solid fibre to eliminate Fresnel reflection at the air-glass interface, reducing both back-reflection and loss.

Using this approach, we have been able to achieve interconnection losses of below 0.4 dB between SMF-28 and HC-PBGF fibres, with < 30dB back-reflectivity.

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Platform performance report: High-Performance Silica Optical Fibres

Power scaling limits in high power fibre lasers Challenge To understand the physical effects determining single mode ultimate power scaling limits, which have so far proved a barrier to harnessing the full potential of fibre lasers, despite their phenomenal success in many application markets.

Background Fibre lasers significantly outperform all other competing technologies, offering record output powers and beam qualities, quantified by the beam-parameter product (BPP). These range from single mode (SM) 10 kW with a ~0.4 mm-mrad BPP, to multi-mode (MM) 100 kW with a 16 mm-mrad BPP, achieved with record wall-plug efficiencies (WPE) in the range of 35-45%. It is this unique combination which has enabled fibre lasers to achieve exceptionally fast growth and high market penetration, replacing existing technologies and dominating entire application sectors, such as marking and gas-free remote cutting.

Progress We have investigated the power scaling limits in Ytterbium-doped fibre lasers operating in the 1 Îźm window. In addition to well-known optical nonlinear effects, power scaling in SM fibre lasers and amplifiers has been seriously hindered by a new non-linear effect - known as transverse modal instability (TMI).

TMI amounts to a threshold-like onset of transverse spatial mode competition which severely degrades the output beam quality and makes the laser unusable.

We have observed TMI experimentally in a large variety of Yb3+ doped optical fibres under different pumping and seeding conditions (Figure 1).

In the case of broad linewidth operation (Î&#x201D;v > 25 GHz), when plotted against the active fibre core diameter, the high power fibre amplifier TMI threshold was shown to be largely inversely proportional to the core area, regardless of the type of fibre used (Figure 1: top data set - broad linewidth).

However, in the case of narrow linewidth operation (Î&#x201D;v < 25GHz), the dependence of the TMI threshold on the core diameters appeared far more severe (Figure 1: lower data set, narrow linewidth), demonstrating a strong effect of the seed linewidth on the TMI threshold.

In contrast, the Stimulated Raman Scattering (SRS)/Stimulated Brillouin Scattering (SBS) power thresholds were shown to increase with the core area, placing conflicting requirements on the fibre design.

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In practical monolithic high power fibre laser systems, the active fibres should be bendable, therefore restricting the maximum cladding diameter to ~600 μm for reasons of mechanical reliability.

Mechanical reliability, along with TMI, SRS and pump brightness, limits output powers to around 28 kW (diode-pumping) and 52 kW (tandem-pumping) (Figure 2).

Figure 1

Achieving these power levels has required the development of special low-moded fibres with core diameters in the 45-55 μm range. By setting a practical limit of current maximum core diameter to ~35 μm, we have reduced the power limits to around 15 kW with diode- and 25 kW with tandempumping. This implies that combining only four tandem-pumped SM fibre lasers could result in a 100 kW laser with a beam parameter product (BPP) of ~1.3 mmmrad, or with eight SM fibre lasers, a 200kW laser with a BPP of ~1.6 mm-mrad could be achieved.

These new ‘ultra-bright’ laser sources would represent an order of magnitude improvement in brightness as compared to the current state-of-the-art. Such a step change in performance, achievable only through harnessing fibre technologies, would stand to impact future manufacturing and directed energy applications, as well as ambitious, futuristic endeavours such as fibre-based particle accelerators, space debris removal and laser-propelled nanocraft interstellar flights i.e. the Breakthrough Starshot Initiative.

Figure 2 13

Platform performance report: Light Generation and Delivery

Development of lasers for photonics integration with reduced power consumption Challenge To develop new lasers which consume less power for energy efficient optical networks and integrated sensor chips.

Background The development of lasers with lower total power consumption is a critical factor for most photonic applications. In telecommunications networks, reducing power consumption increases the overall efficiency of the network whilst also allowing lasers to operate without active cooling. In applications such as remote sensing, the development of low power consumption lasers opens up the potential for the wide-scale deployment of smart sensing technologies.

Progress Our research has focused on the development of novel laser structures and laser manufacturing technologies in order to tackle the problem of power reduction and fabricate structures compatible with further photonics integration.

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We have continued to develop quantum dot lasers using the industriallycompatible process of metal organic vapour phase epitaxy. Quantum dot lasers have reduced sensitivity to operating temperature and our laser research on gallium arsenide (GaAs) substrates has yielded room temperature functioning at around 1.1 μm.

We are now targeting new structures to extend this result to the fibre-compatible wavelength of 1.3 μm. We have also demonstrated quantum dots on indium phosphide (InP) substrates which show emission wavelengths out to 2.1 μm and expect this new development to be significant in addressing both 1.55 μm lasers for standard long-haul telecommunications infrastructure, and the growing interest in 2 μm wavelengths for new communications bands, including those arising from new fibre technologies generated by the Hub. Our observation of emission at 2 μm further gives rise to the possibility of low power quantum dot lasers for sensing applications. Inter sub-band lasers such as quantum cascade lasers struggle to achieve wavelengths as short as 2 μm, and inter-band lasers relying on quinternary Antimonide-containing materials, such as AlInGaAsSb, are extremely challenging to produce by current epitaxial methods. Whilst work remains to extend our new quantum dot technology further in order to achieve laser operation, this opens up a promising new avenue of research within the field.

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Platform performance report: Light Generation and Delivery

Ultra-compact optical amplifier in the 2 μm wavelength region Challenge To develop a new class of optical fibre amplifier for use with short pulse lasers operating in the 2 µm wavelength region.

There is a growing demand for this type of laser, and adequate amplifiers are also needed for several applications requiring increasingly higher output powers. To mitigate optical nonlinear effects arising at high peak powers, the optical path of light inside the amplifier length must be maximally short. The silica glass commonly used for optical fibres only allows for low doping concentrations in the amplifying Tm3+ ions, hence the need for long fibre lengths to achieve suitable amplification levels.

Our aim is to develop an optical fibre platform based on a different glass family with the potential to produce centimetre-long optical amplifiers.

Progress We have developed two thermally-compatible germanate glasses in the GeO2-PbO-ZnO-Na2O-Nb2O3 system and demonstrated the ability to draw these glasses into a large core single mode fibre with a core diameter of 20 µm and numerical aperture of 0.07. Our focus over the last year has been to develop compact lasers and amplifiers operating in the 2 µm region using short lengths (21 cm) of this Tm-doped germanate fibre.

Figure 1: (above) cross-sectional image of the germanate fibre.

To date, we have developed a single mode fibre laser operating at 1952 nm, in-band pumped at 1565 nm, which achieved a ~1.5 W maximum output power. This result was limited only by the available pump power. A high slope efficiency of 55.9% was also obtained which, alongside the output power, represents a record result for this particular glass system.

The measured pump absorption was also very similar to the levels achieved in state-of-the-art alumino-silicate fibres despite this fibre type having benefited Figure 2: (right) Laser output power at 1952 nm from optimisation over many years. In contrast to alumino-silicate technology, versus absorbed pump power; our fibre offers a simpler step-index refractive index profile, better suited to the inset shows the laser cladding pumping; conventional technology requires the addition of a pedestal spectrum. in the fibre’s refractive index profile which for many practical applications, is undesirable.

Our record results were achieved without any particular optimisation of the dopant concentration. With additional work, this could be increased and as a result produce an even greater reduction in the length of the required fibres.

We are confident that with further dehydration of the cladding, performance may be even further enhanced. Our results, therefore show Tm3+ doped germanate LMA fibre as a promising candidate for high power fibre laser applications at 2 µm, particularly in the short pulse regime where managing non-linearity is a key issue.

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Future plans Our future work will aim to optimise the doping concentration and further reduce the water absorption in the host glass in order to transform this platform into a serious competitor to the more mainstream silica-based Thulium-doped fibre technology. We will also work towards including a second cladding in the fibre in order to produce a cladding pumped version, a critical step towards increasing the available pump power.

Case study: IS-Instruments Ltd The detection, monitoring and control of gaseous species within the energy sector, and specifically the nuclear industry, is critical for ensuring safety, environmental control and efficiency savings. A particular area of interest lies in monitoring hazardous gases in long-term waste storage systems. There is demand for next-generation measurement technologies with improved sensitivities, for instance at sub parts per million (ppm) levels, to replace existing high-cost and high-maintenance systems.

Aims: The Future Photonics Hub is supporting IS-Instruments (ISI) to develop a new disruptive Raman analysis instrument which will deliver the sought-after, dramatic improvements in sensitivity and prove competitive to existing techniques, such as infrared absorption of Gas Chromatographs. The Hub is playing a key role in developing the instrument through the design and fabrication of hollow-core optical fibre, an integral part of the sensing system.

Outcomes: The hollow-core fibres developed by the Hub have enabled the sensing of a wide range of gases in diverse environments, spanning nuclear and conventional energy sectors. These fibres have been integrated within a prototype Raman sensing system, forming an essential component, allowing a long interaction length with the gas. Having demonstrated the technology, ISI is now undertaking field trials with application partners in the nuclear sector and recognises the potential of this transferable technology to other sectors.

â&#x20AC;&#x153;The Future Photonics Hub is an excellent partner for the development of speciality fibres due to its unique manufacturing capabilityâ&#x20AC;?.

Dr Mike Foster, Founder, IS-Instruments.

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Platform performance report: Silicon Photonics

Integrated photonic circuits at longer wavelengths Challenge To manufacture silicon (Si) and germanium (Ge) photonic material platforms with transparency limits of eight and 15 microns respectively, and to integrate active photonic components (modulators, detectors and lasers) with Si and Ge passive circuits.

Progress In order to realise integrated photonic circuits at the longer wavelengths required for sensing applications, our research has focused on demonstrating passive suspended Si devices at ~8 μm, suspended Ge waveguides and Si and Ge modulators, alongside integrating Quantum Cascade Lasers (QCLs) with Ge-on-Si platforms.

After our successful demonstration of suspended Si waveguides and couplers operating at ~8 μm, we have further realised MMI splitters and Mach-Zehnder interferometers at this wavelength. The outcome of these developments has been completing a core set of passive devices which will enable us to achieve integrated photonic circuits on this platform.

We have also made significant progress in the suspended Ge platform, demonstrating low loss waveguides at ~8 μm. Our approach involved growing Ge on thin silicon-on-insulator (SOI) wafers, with subsequent one dry and two wet etching steps to remove both the SiO2 cladding and thin Si layer.

Using this approach, we have been able to achieve air gaps larger than the SiO2 thickness (Figure 1). This feature is of key importance for developing Ge suspended devices at wavelengths > of 10 μm, since relatively large gaps are needed to reduce leakage from the optical mode to the Si substrate.

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Figure 1: Suspended Ge for long wavelength operation.

For active photonic devices in Si and Ge, we have reported carrier-depletionbased modulators in Si which have achieved a data rate of 20 Gbit/s at a wavelength of 2 μm. This result is an order of magnitude improvement on the previous state-of-the-art reported by IBM. We have also reported efficient carrier injection modulators in both Si and Ge at wavelengths of up to 8 μm.

In addition, we have designed and fabricated mid-infrared SOI circuits for integrating with QCLs, fabricated by the National Epitaxy Facility in Sheffield.

Two methods have been trialled: transfer printing QCLs, a method developed in collaboration with the University of Strathclyde and flip-chip bonding. Details of both approaches are provided in the ‘Integration’ platform performance report (see page 26).

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Platform performance report: Large-Scale Manufacture of Metamaterials and 2D Materials

Uniform wafer-scale deposition of 2D materials Challenge To modify our manufacturing methods in order to overcome key barriers to large-scale industrial uptake.

Background The optical quality of the 2D materials that we have previously developed demonstrates the expected theoretical performance, particularly in respect of fluorescence, as observed by optical pumping, and structure, as verified by Raman spectroscopy. However the electrical properties, for example the carrier mobility, film resistance and carrier concentrations, can vary by several orders of magnitude from the theoretical expectations. This is particularly problematic for molybdenum disulphide (MoS2), which is used for transistor fabrication.

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An additional challenge which emerged during our research concerned the patterning of 2D films by photolithography. The alkaline solutions used in most photoresist developers attack MoS2, causing the films to dissolve or lift off.

Moreover, the photoresists exhibit extremely strong adhesion, making complete removal very difficult due to the increased risk of damaging the film.

Progress After testing 11 different protocols for MoS2 deposition and post-processing, we have been able to reduce the surface roughness from 6 nm to < 1 nm.

Decreased roughness is associated with fewer grain boundaries, leading to increased mobility through decreased sheet resistance.

We solved the challenge associated with using conventional photoresists by developing a double layer technique, involving the deposition of a protective buffer layer between the 2D material and the photoresist. These process changes enabled us to fabricate high quality devices (as illustrated in Figures 1, 2 and 3).

Figure 1: Graphene/MoS2

Figure 2: Large area MoS2/WS2

Figure 3: MoS2 with Graphene Au

To date, our research has focused primarily on MoS2 due to its unique properties as a semiconductor; MoS2 is the first material with a 2D geometry to provide the electrical properties of silicon. However, we have recently expanded our work to encompass several other promising 2D materials which we plan to explore further. Key areas of interest include, for example, integration with optical fibre devices and microstructured fibres, developing 2D hybrid bismuth oxy-halides and direct writing 2D planar structures.

Our work has attracted the attention of Merck Chemicals which has fully funded a PhD student to work in the field. We are also working with a UK-based SME to develop 2D materials on flexible substrates and have recently been awarded a European-funded project (Smart2Go) in this research area.

We continue to develop new 2D materials and to date, we have distributed samples to ten industrial and academic collaborations internationally, by means of formal material transfer agreements. We are currently exploring licensing opportunities with industry, though our manufacturing protocol remains unpublished whilst work is underway on dependent devices for Intellectual Property.

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Platform performance report: Large-Scale Manufacture of Metamaterials and 2D Materials Developing new functional metamaterials and processes Challenge To develop new functional metamaterials and processes for low-cost, highthroughput manufacturing of metamaterials and to enable their integration with optoelectronic, planar waveguide and optical fibre technologies.

Progress High-throughput materials discovery Using high-throughput physical vapour deposition and characterisation techniques, we have concluded a systematic study of the compositional dependence of the UV to near-infrared (NIR) optical properties of Bi:Sb:Te (BST) semiconductor alloys over the widest stoichiometric range reported to date [1-9].

These semiconductor alloys offer a uniquely broad range of optical properties complementary to those of noble metals, conductive oxides, and nitrides for metamaterial and nanophotonic applications. They exhibit plasmonic figures of merit higher than metallic nitrides and transparent conductive oxides across the entire spectral range, and in excess of gold, from the UV up to around 550 nm. These semiconductor alloys also support dielectric (Mie) resonances better than conductive oxides at NIR wavelengths (including telecommunications) beyond ~1200 nm. In addition, their epsilon-zero wavelengths can be tuned from the UV to NIR by composition, they can present sub-unitary refractive indices in the UV to high-energy-visible range, and exhibit record-high NIR refractive indices (up to 11.5).

Reconfigurable nanomechanical metamaterials We have continued to develop nanomechanical metamaterial device functionalities, demonstrating that thermally-activated optical memory can be achieved via the nanostructural reconfiguration of a nanowire metamaterial array made from a nickel-titanium shape-memory alloy [10]. This nanostructured thin film of gold-coated Ni:Ti alloy exhibits non-volatile bistability in its optical properties upon temperature cycling between 30 and 210 °C, achieved via differential displacement of nanowires underpinning transformations between the alloyâ&#x20AC;&#x2122;s martensite and austenite phases.

We have also delivered the first experimental demonstration of electrooptic modulation functionality based on electrostriction in an all-dielectric, mechanically-reconfigurable photonic metamaterial [11, 12]. The device comprises an array of nanowires, manufactured in a free-standing bilayer membrane of silicon and a transparent conductive oxide. Under the application of an electric field, a reversible nanoscale deformation occurs bringing about substantial changes in optical transmission at NIR wavelengths selected by design and resulting in effective electrostriction and electro-optic coefficients several orders of magnitude greater than those of bulk dielectric media.

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Such modulators, based upon artificial, resonantly-enhanced electrostriction in membrane-based nano-mechanically reconfigurable metamaterials, may be used for laser Q-switching and mode-locking, amongst other applications which call for modulation at megahertz frequencies and/or high levels of integration.

Metamaterial and metadevice integration with optical fibre waveguides We have successfully demonstrated picosecond (ps) ‘dark pulses’ generated using our fully-fiberised and packaged metadevice for all-optical signal modulation, based on coherent absorption [13]. This device, realised by our team last year, produces pulses based on the interaction of mutually coherent signals of different durations. For example, a 1 ps control pulse can selectively trigger the absorption of part of a longer signal pulse, resulting in the formation of a 1 ps dark interval within the signal pulse [14].

References: [1] D. Piccinotti, B. Gholipour, J. Yao, K. F. MacDonald, B. E. Hayden, and N. I. Zheludev, “Optical Response of Nano-hole Arrays Filled with Chalcogenide Low-epsilon Media,” Adv. Optical Mater. 6, 1800395 (2018).

B. Gholipour, J. Yao, B. E. Hayden, and N. I. Zheludev, “Extraordinary Properties of Chalcogenide Metamaterials,” in 12th International Congress on Artificial Materials for Novel Wave Phenomena (Espoo, Finland, 2018).

[2] D. Piccinotti, B. Gholipour, J. Yao, K. F. MacDonald, B. E. Hayden, and N. I. Zheludev, “Compositionally controlled plasmonics in amorphous semiconductor metasurfaces,” Opt. Express 26, 20861-20867 (2018).

[9] K. F. MacDonald, D. Piccinotti, B. Gholipour, J. Yao, B. E. Hayden, and N. I. Zheludev, “New materials for metamaterials: plasmonic and ENZ chalcogenides,” in SPIE Photonics Europe 2018 (Strasbourg, France, 2018).

[3] D. Piccinotti, B. Gholipour, J. Yao, K. F. MacDonald, B. E. Hayden, and N. I. Zheludev, “Chalcogenide semiconductor alloys for photonic applications: high- and low-index, plasmonic and low-epsilon properties,” (Submitted).

[10] Y. Nagasaki, B. Gholipour, J. Y. Ou, M. Tsuruta, E. Plum, K. F. MacDonald, J. Takahara, and N. I. Zheludev, “Optical bistability in shapememory nanowire metamaterial array,” Appl.

Phys. Lett. 113, 021105 (2018).

[4] B. Gholipour, D. Piccinotti, A. Karvounis, K. F. MacDonald, and N. I. Zheludev, “Reconfigurable ultraviolet and high-energyvisible dielectric metamaterials,” (Submitted).

[5] J. Li, B. Gholipour, D. Piccinotti, K. F. MacDonald, and N. I. Zheludev, “Hollow-core waveguides with n<1 chalcogenide cladding,” in 7th International Topical Meeting on Nanophotonics and Metamaterials (Seefeld-inTirol, Austria, 2019).

[6] B. Gholipour, D. Piccinotti, A. Karvounis, K. F. MacDonald, and N. I. Zheludev, “Chalcogenide Phase-change Photonic Metamaterials,” in MRS Spring Meeting 2019 (Phoenix, AZ, USA, 2019).

[7] D. Piccinotti, B. Gholipour, J. Yao, K. F. MacDonald, B. E. Hayden, and N. I. Zheludev, “Extraordinary Properties of Epsilon-Near-Zero and Low-Index Chalcogenide Metamaterials,” in Conference on Lasers and Electro-Optics 2018 (San Jose, CA, USA, 2018).

[8] K. F. MacDonald, D. Piccinotti, A. Karvounis,

[11] A. Karvounis, B. Gholipour, K. F. MacDonald, and N. I. Zheludev, “Giant electro-optical effect through electrostriction in a nano-mechanical metamaterial,” Adv. Mater., 1804801 (2018).

[12] A. Karvounis, B. Gholipour, K. F. MacDonald, and N. I. Zheludev, “Giant electro-optic effect via electrostriction in a dielectric nanomechanical metamaterial,” in 7th International Topical Meeting on Nanophotonics and Metamaterials (Seefeld-in-Tirol, Austria, 2019).

[13] A. Xomalis, I. Demirtzioglou, E. Plum, Y. Jung, V. Nalla, C. Lacava, K. F. MacDonald, P. Petropoulos, D. J. Richardson, and N. I. Zheludev, “Fibre-optic metadevice for alloptical signal modulation based on coherent absorption,” Nat. Commun. 9, 182 (2018).

[14] A. Xomalis, I. Demirtzioglou, Y. Jung, E. Plum, C. Lacava, P. Petropoulos, D. J. Richardson, and N. I. Zheludev, “Picosecond all-optical switching and dark pulse generation in a fibreoptic network using a plasmonic metamaterial absorber,” Appl. Phys. Lett. 113, 051103 (2018).

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Platform performance report: Integration

Free-standing mid-infrared waveguides for trace gas spectroscopy and environmental monitoring Challenge To develop a free-standing mid-infrared (mid-IR) waveguide platform, using simple and mass-producible fabrication technology, which is highly sensitive and robust for trace toxic gas sensing applications.

Progress We have developed a free-standing Ta2O5 waveguide platform for chipbased mid-IR gas sensing applications. Isotropic dry-etching of silicon has been performed using XeF2 gas to undercut the substrate below the Ta2O5 waveguides. These waveguides have been designed in such a way that a 50% evanescent field overlaps with the surrounding medium. Therefore, gas sensing occurs on both the top and bottom side due to the holes present on the membranes. We have shown these waveguides to be successful in guiding light from visible to mid-IR wavelengths.

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Figure 1: Schematic of the freestanding Ta2O5 waveguide on silicon substrate.

a

b

Figure 2: SEM images of the free-standing Ta2O5 rib-waveguide showing the etch holes (a) and membrane (b).

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Platform performance report: Integration

Integration of mid-infrared emitters and detectors on a silicon/germanium photonics platform Challenge To demonstrate the integration of semiconductor devices such as lasers, LEDs and detectors with photonics chips based on silicon and germanium.

Progress Our research aims to develop new manufacturing methods which allow for the integration of photonics components, for example lasers, LEDs and detectors, with passive semiconductor components, including waveguides, modulators and interferometers, on silicon or silicon/Ge platforms. The overall objective is to demonstrate new forms of integrated smart photonics chips for devices such as sensors, spectrometers, quantum processors and lab-on-a-chip diagnostic tools.

We have investigated a range of methods to remove and transfer devices from one substrate on to another host bearing the full range of heterogeneously integrated devices. Two technical approaches were explored in particular detail - a novel micro-transfer printing method and a flip-chip process.

Novel micro-transfer printing approach Working with the University of Strathclyde and investigators involved in the Hubâ&#x20AC;&#x2122;s own Silicon Photonics Technology Platform, we have demonstrated the use of micro-transfer printing to transfer Quantum Cascade Lasers (QCLs) from an indium phosphide (InP) substrate to a processed silicon substrate. In order to achieve this, we had to develop new etching and fabrication processes to deal with the unique properties of QCLs; QCLs are typically far larger than normal semiconductor lasers (up to 6 Îźm in thickness) and therefore present a challenge for the standard micro-transfer printing approaches typically used to produce, for example, LEDs and short wavelength lasers etc.

Figure 1: Quantum Cascade Laser membrane integrated with Silicon waveguides.

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Our new process entailed under-etching the lasers in order to create very thin, yet mechanically-stable, membranes, held in place by thin tethers of semiconductor material. An elastomer stamp was used to transfer the lasers to the patterned silicon substrates before carrying out device integrity tests.

Through successfully demonstrating a full laser transfer process, we have made a significant step towards achieving our target of integrated mid-infrared (mid-IR) sensor chips. Over the next year, we plan to build on this result, improving the transfer process yield, testing laser properties, investigating reliability and integrating with waveguide technologies built into the Si/SiGe platform.

Flip-chip approach We have developed fully-fabricated QCL laser bars and performed a flip-chip process to integrate them with a fabricated silicon photonics template, including waveguides and modulators. Whilst flip-chip technology is established for many types of devices, it is less developed for use in transferring mid-IR QCLs and we have therefore had to overcome several challenges to demonstrate the process. We will continue to develop this approach and compare its performance and operational parameters with those of the transfer printing method.

We have also begun to collaborate on applications of the technology with the University of Oxfordâ&#x20AC;&#x2122;s department of Chemistry. Support from the Hubâ&#x20AC;&#x2122;s Innovation Fund has enabled us to work with Professor Grant Richie to develop an integrated gas sensing system for clinical use in monitoring the lung function of paediatric patients with cystic fibrosis.

Mid-IR lasers can be used to detect the concentration of excreted and tracer gases in patientsâ&#x20AC;&#x2122; breath and, combined with a comprehensive model of lung physiology, it is possible to create a system which accurately diagnoses and monitors lung dysfunction. This system has already been demonstrated for adult patients with pulmonary disease but paediatric monitoring presents different challenges which require more integrated and compact photonics systems.

The demand for new lasers and need to combine numerous components, such as optical cavities, lasers and bespoke mid-IR fibres, on to an existing engineering system presents the ideal opportunity for us to further our work towards achieving photonics integration for important healthcare applications.

Figure 2: Prototype system for paediatric lung function measurement, designed and built at the University of Oxford.

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Building agile capability

Our ÂŁ1 million Innovation Fund supports new avenues of research which arise in response to the evolving demands of industry.

Our dynamic model is achieved through regular thematic calls for proposals to stimulate new industry-focused research partnerships with academia. This ensures that the Hub remains agile and responsive to emerging industrial needs and helps drive the UK photonics manufacturing ecosystem.

Since launching the fund in 2016, we have run two calls for proposals seeking to increase the depth and breadth of our existing capabilities in alignment with our four Technology Platforms and the Grand Challenge of Integration.

From 41 applications, nine projects have been funded to date, to a total value of ÂŁ0.5 million*.

2016-2018 Innovation Fund projects: n Measuring

lung inhomogeneity by paediatric cystic fibrosis, University of Oxford

n Large-scale

manufacturing of metamaterials with direct laser writing, University of Southampton

n Integrated

graphene on Ge/Si platform for mid-IR photodetectors, University of Cambridge

n Chiral

light sensor fabricated by chiral light, University of Oxford

n Low

cost manufacturing of integrated LIDAR arrays, University of Southampton and Imperial College London

n Parallel

micro-assembly of quantum cascade lasers on germanium, University of Strathclyde

n Manufacturing

process of laser fibre depolariser, University of Southampton and Phoenix Photonics

n 3D

interconnect technologies, Heriot-Watt University

n All-dielectric

surface wave devices for light generation with 2D material, University of Bristol

*Grants funded at 80% FEC

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Hub University of Southampton University of Sheffield I nnovation Fund partners 2016-2018 Heriot-Watt University University of Bristol University of Cambridge University of Oxford University of Southampton with Imperial College, London University of Southampton with Phoenix Photonics University of Strathclyde Industry partners International industry partners by country Distribution of UK photonics industry activity

Sweden

USA USA

China Italy 29

Making a positive contribution to the UK economy Our first three years of operation have focused on delivering core research within our four Technology Platforms and conducting specific projects with UK industry.

Our industrial engagement programme aims to stimulate collaborative research and development projects with companies in the photonics supply chain and photonics-enabled sectors, such as telecommunications, healthcare, defence and aerospace. We work with businesses of all sizes, ranging from multinationals to SMEs, as well as engaging with key representatives of UK industry to raise awareness of the value of photonics both in delivering transformational manufacturing technologies and driving economic growth.

Our research projects target new, practical solutions to photonics manufacturing challenges and help accelerate the commercialisation of new technologies made in the UK, to the advantage of the UK economy.

Industry collaborations We have secured significant funding in each of our four Technology Platforms, working with companies involved in the photonics supply chain and photonicsenabled industries such as materials processing, energy, data storage and automotive.

In 2018, we have successfully secured industry-funded projects within all four of our Technology Platforms. Our activities under the Grand Challenge of Integration have been supplemented by some targeted projects following the award of funding from the Defence and Security Accelerator (DASA).

Over ÂŁ11M industry collaborations

56 projects over four Technology Platforms

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8

industry sectors: sensing, defence, photonics, data comms, storage, LIDAR for autonomous vehicles, aerospace and advanced materials

Industrial engagement Technology Platform

Direct industry contributions* High-Performance Silica Optical Fibre

£1,777,300 Light Generation and Delivery

£3,169,700 Silicon Photonics

£2,782,900 Large-Scale Manufacturing of Metamaterials & 2D Materials

£789,500 Integration

£385,000 Other photonics manufacturing research areas

£2,180,800 £0k

£3.5M

Cumulative income, January 2016 - December 2018 32%: competitively won grants £10,248,700 33%: core funding £10,220,300

35%: industrial funding £11,085,200

*Based on signed contracts from industrial collaborations, since 2016

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Industrial engagement

Exhibitions Our 2018 industrial engagement strategy elected to prioritise expanding the Hubâ&#x20AC;&#x2122;s national reach, consolidating our central role within the UK photonics community and further targeting UK manufacturing industries which stand to benefit from photonics-enabled solutions.

To increase and sustain our interactions with these key stakeholders, the Hub showcased its technologies at six national exhibitions and industry showcases, two in each quarter of the year. These included the KTNâ&#x20AC;&#x2122;s Emerging Technologies Showcase (London), Farnborough Airshow and Innovation South (both Farnborough), Photonex photonics trade show (Coventry), and the Materials Research Exchange (London) and Advanced Engineering Show (Birmingham) which were both especially successful in enabling us to reach brand new audiences in the automotive, aerospace, and security sectors.

At each event, Hub researchers and members of our business development team were on hand to discuss prospective collaborations with exhibition visitors and to provide live demonstrations of new technologies such as multispectral imaging using novel glasses and a new optical fibre-based vibration sensing system. Hardware demonstrators proved particularly strong catalysts for industrial lead generation and we are currently working to add new examples to our portfolio for 2019.

The forthcoming year will see the Hub deepen its connections with prospective collaborators by targeting selected international exhibitions within those photonics end-user industries which have responded with particular promise to our 2018 industrial engagement activities.

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Hub Industry Day The Hub’s 2018 Industry Day was the major focal point of this year’s industrial engagement calendar. Held at the University of Southampton in September, this one day conference and trade show was our largest event to date, attracting more than 200 delegates from the photonics industry and photonicsenabled sectors including defence and aerospace, data communications and storage, manufacturing, microelectronics and materials, as well as 28 exhibiting companies.

Keynote speaker Dr Benn Thomsen of Microsoft Research opened the day with a presentation on ‘Challenges and Opportunities for Photonics in the Cloud’, providing a pertinent industrial perspective leading into the first technical session, ‘Solutions for Next-Generation Data Communications’.

Other sessions showcased major developments from the Hub’s key Technology Platforms - higher power, more efficient lasers, volume manufacturing of 2D and metamaterials and integrated, compact, low cost smart devices, as well as a session reviewing the UK photonics manufacturing sector, which included invited speakers Georgios Papadakis (Innovate UK) and Ben Whitaker (Defence and Security Accelerator) highlighting forthcoming funding opportunities.

The programme was designed to bring collaboration to the fore and activities such as a business brunch and speed-networking, alongside access to flexible meeting space and dedicated exhibition time, enabled attendees to establish new contacts and discuss ways of working together. Responding to the postevent survey, more than 90% of delegates reported gaining an increased knowledge of new photonics fabrication processes which they could foresee being used in future manufacturing and over 90% of exhibitors generated new leads as a result of participating. Furthermore, 100% of delegates and exhibitors said that they would attend future Hub events, a success we intend to build upon in 2019 by holding our Industry Day in Sheffield, co-located with the long-established UK Semiconductors conference.

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Progress in promoting photonics

Influence The Hub has continued to support national leadership in photonics, working closely with the Photonics Leadership Group (PLG). Government engagement with the PLG has increased significantly throughout 2018, providing formal and informal consultation to multiple departments in areas including the UK National Quantum Technologies Programme and proposed new National Security and Infrastructure Investment legislation, which stands to impact on the control of assets including intellectual property.

In collaboration with the PLG, the Hub is fully engaging with the UK 2017 Industrial Strategy, highlighting the significant impact of photonics on the Government’s four Grand Challenges and seeking the most effective way to align photonics with the Industry Strategy Challenge Fund. Our involvement has included supporting a number of photonics-orientated bids to Wave 3 of the Fund and seeking strategic engagement with the successful projects.

Communications Increasing awareness of the Hub and the impact of photonics technologies has continued as a primary focus throughout our 2018 communications activities. We have developed and delivered a varied campaign targeting different key stakeholders, including direct engagement with the photonics and end-user communities at UK-based exhibitions and conferences, securing coverage in mainstream press and promoting photonics across our social media platforms through the use of striking imagery and stories of wider public appeal.

Highlights of the year have included our research featuring in a BBC4 science documentary ‘The Secret Story of Stuff: Materials of the Modern Age’ presented by Zoe Laughlin, Director of the Institute of Making at University College London. The programme was broadcast at 9pm on Wednesday 31 October 2018 and attracted in the region of two million viewers. More than 12 minutes of the documentary were dedicated to photonics at the University of Southampton’s Optoelectronics Research Centre, including the Hub’s research within our cleanrooms and members of our Lightwave Roadshow team demonstrating some of the experiments used in our public outreach work.

The International Day of Light (IDoL) on 16 May 2018 also provided the ideal opportunity to promote our outreach activities and develop media content for our online channels.

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In May, we published a market report on the UK photonics industry in collaboration with Innovate UK and the PLG. Our 2018 publication, â&#x20AC;&#x2DC;UK Photonics: The Hidden Economic Engineâ&#x20AC;&#x2122;, expanded on previously reported market size data and highlighted the vast ÂŁ13.9 billion contribution from UK photonics manufacturing industries to the UK economy.

Over the course of the year, we issued a series of 16 press releases announcing our latest research developments and forthcoming events in our industrial engagement programme. Our regular electronic newsletter has also been successful in keeping our mailing list of subscribers abreast of news, events, and funding opportunities. Reader engagement with this publication has remained strong with an average open rate of more than 40%, over twice the sector average.

Our social media presence on platforms such as Twitter, has also continued to grow considerably through using the @PhotonicsHub handle to interact with our industry partners, other research organisations and popular science communities. The Hub Industry Day prompted an especially significant increase in audience engagement through our social media channels and during 2019, we plan to refresh our website to become more interactive and engaging.

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Photonics for the next generation

The Hub’s outreach programme engages with schools and the public to raise awareness of our research, highlight the far-reaching impact of photonics on daily life and promote opportunities to study and pursue careers in physics.

A key aim of the programme is to reach underserved audiences, including working with ‘Widening Participation’ (WP) schools and encouraging greater gender equality in the science and technology fields.

Our 2018 outreach activities have reached over 6,100 students, teachers and members of the public. Major events have included the Lightwave Roadshow with hands-on optics activities, the Light Express Roadshow incorporating a laser light show, Photonics Explorer teachers workshops accompanied by free kits to use in the classroom, and an EU-funded project linking universities and community ‘makers’ workshops (PHABLABS 4:0).

To date, we have worked with: n Over

17,000 school pupils, college students, teachers and members of the public n Over 90 schools n Delivered over 75 events in partnership with eight different organisations.

By working in partnership with organisations such as the Cheltenham Science Festival, we have reached 1,000 more of our target audience than planned, including large numbers of parents, members of the general public and GCSE and A-Level students and teachers.

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â&#x20AC;&#x153;...the afternoon was brilliant and certainly inspired many of our students, the questions from the students continued into the following week and has generated some excellent science.â&#x20AC;?

Head Teacher, Applemore College.

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The Future Photonics Hub team

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Deputy Director and Manager: Professor Gilberto Brambilla, University of Southampton

Business Development Manager: Tom Carr, University of Southampton

Co-Investigator: Professor Martin Charlton, University of Southampton

Coordinator: Ruth Churchill, University of Southampton

Deputy Director: Professor Jon Heffernan, University of Sheffield

Co-Investigator: Professor Dan Hewak, University of Southampton

Public Engagement Leader: Pearl John, University of Southampton

Industrial Liaison Manager: Dr John Lincoln

Co-Investigator: Professor Goran Mashanovich, University of Southampton

Principle Investigator and Director: Professor Sir David Payne, University of Southampton

Co-Investigator: Professor Francesco Poletti, University of Southampton

Co-Investigator: Professor Graham Reed, University of Southampton

Co-Investigator: Professor David Richardson, University of Southampton

Co-Investigator: Professor Jayanta Sahu, University of Southampton

Marketing Manager: Rebecca Whitehead, University of Southampton

Co-Investigator: Professor Michalis Zervas, University of Southampton

Co-Investigator: Professor Nikolay Zheludev, University of Southampton

Industry partners

Our current industry partners include: n Carbon

Trust

n Breakthrough

n Huawei n Honeywell n II-VI

Aerospace

Photonics

n IQE n IS

We have also secured financial support from funders including:

Instruments

n Lightpoint

Medical

Prize

n Defence

Science and Technology Laboratory (DSTL)

n European

Office of Aerospace Research & Development

n Engineering

and Physical Sciences Research Council (EPSRC)

n Lumenisity

n European

n Merck

n Horizon

n Microsoft

n Innovate

Commission

2020 UK

n NorthLab

Photonics

n Royal

Academy of Engineering

n Northrop

Grumman

n Royal

Society

n Oclaro n Phoenix

Photonics

n PragmatIC

Printing

n QinetiQ n Rockley

Photonics

n Seagate

Ireland

n Sestosensor n SPI

Lasers

Connect If you are interested in learning more about the Future Photonics Hub, or finding out how we can work with you, please contact us: +44 (0)23 8059 9536 contact@photonicshubuk.org www.photonicshubuk.org Follow us @PhotonicsHub

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Outreach event 2018: Light Express Roadshow laser light show and photonics lecture

www.photonicshubuk.org contact@photonicshubuk.org +44 (0)23 8059 9536 Follow us @PhotonicsHub

A future manufacturing research hub