of the flat focusing mirror with subwavelength gratings was proposed by Prof. Javier Redondo in Gandia. He observed the sound wave can be focused by a layer of periodic scatters and we try to realized this idea in optics. I love to visit the group in Gandia for their beautiful beach, nice weather, delicious seafood and so on. With the accompany of such nice environment, I also learned how to simulate sound waves propagation with the commercial software, COMSOL there. I mainly worked with a PhD student, Alejandro Cebrecos, who is one of the Spanish hardest worker I have ever seen. We have stayed lately in the lab several times until the security came to kick us out. We have tried to establish experiments in acoustics such as the focusing of evanescent wave in transmission based on fluid-like scatters. The experiment of sound waves is very attractive because I can see the structure of a real photonic/sonic crystals. Build them with my hands and my eyes without any precise instrument or microscope is real impressive.