Compact Eight-Channel Thermally Reconfigurable Optical Add/Drop Multiplexers on Silicon

Abstract

A compact thermally reconfigurable optical add/drop multiplexer (ROADM) is realized with 500 $\text {nm}\times 220$ nm silicon-on-insulator (SOI) strip waveguides. The demonstrated ROADM has eight channels with a channel spacing of 400 GHz and consists of two identical arrayed-waveguide gratings integrated with eight thermo-optic switches on the same chip. These thermo-optic switches have a broad bandwidth with low loss ( 20 dB) for covering all wavelength channels by utilizing point-symmetric Mach–Zehnder interferometers with bent directional couplers. The ROADM’s footprint is about $770~\mu \text {m}\times 880~\mu \text{m}$ only due to the ultra-strong confinement ability of SOI strip waveguides. The total on-chip loss of the fabricated ROADM is $\sim 15$ and $\sim 7$ dB for the transmitted signals and the added/dropped signals, respectively.