Optical spectrum control circuit with flat pass band characteristics using a high-resolution arrayed-waveguide grating

Abstract

We have proposed an optical spectrum control circuit that realizes various kinds of signal processing in the optical domain using a silica-based planar lightwave circuit including arrayed-waveguide gratings. In order to obtain a flat transmission spectrum required for processing an optical signal that has a continuous spectrum, the number of the spectral output waveguides is set more than the number of waveguides in the waveguide array. In this study, we demonstrated a phase error compensation and obtained the flat transmission spectrum with ripples below 0.9 dB. We also demonstrated a tunable bandwidth operation as an example of the spectral amplitude control and a variable pulse delay operation as an example of the spectral phase control, respectively. In the tunable bandwidth operation, the passband characteristic of the minimum bandwidth of 5-GHz and tunable pass-band characteristics with different center frequencies with about 20-dB extinction ratio were obtained. In the variable delay operation, pulse delays equal to calculated values could be observed with some phase settings.