Design and fabrication of optical filters with very large stopband (≈500 nm) and small passband (1 nm) in silicon-on-insulator

Abstract In this paper, we report on the design, fabrication and characterization of a broadband photonic crystal filter. Modeling with a genetic algorithm (GA) was used to investigate the effect of changing the number of periods and thickness ratios of a photonic crystal filter structure with two alternating materials. Theoretical optimized parameters were obtained as a function of wavelength for a photonic crystal filter with a very broad filter bandwidth as well as a very narrow transmission window. We used the determined optimum parameters at a wavelength of 1550 nm to fabricate the structure using e-beam lithography and inductively coupled plasma (ICP) etching. Experimental results show that the structure indeed has a very narrow transmission window and a low loss of just 4 dB. Hence, this structure can be regarded as a high precision filter for optical communication and photonic integrated chip technologies.