that’s problem, i created 2 linear waveguides which is made of SiO2 (Refractive index n=1.4585) in my first sample, but it’s not good enough. Do you have any sample of optical nano filters, i have to design a optical system and i really need some filters, anythihng(bragg grating, PBG, plasmon, TFMF, Mach-Zehnder, ….). I appreciate it ! Thanks, Damian; your help on the project was invaluable