Silicon-based flat-topped wavelength filter for low crosstalk, high fabrication tolerance and wideband operating range for CWDM applications

Abstract

A flat-topped wavelength filter with low crosstalk and high productivity is proposed and theoretically analyzed. The proposed filter scheme is composed of multiple cascade-connected delayed interferometers with several multimode interference couplers with 50:50 and 28:72 split ratios and a directional coupler with a 92:8 split ratio. Theoretical results based on analytic and numerical simulations exhibit flatband spectra over a wavelength range of > 100 nm and low crosstalk of < −20 [dB] with potentially better production yield for fabrication imperfections.