2 × 2 16-ch silicon photonics wavelength-selective switch based on waveguide gratings

We demonstrate a 2 × 2 16-ch silicon photonics wavelength-selective switch consisting of contra-directional couplers and thermo-optic Mach-Zehnder switches. The contra-directional couplers are based on sidewall corrugated Bragg gratings with an unlimited free spectral range and thus enable the device to operate over a very wide wavelength range of the C- and L-band. We obtain a fiber-to-fiber insertion loss of 9.2 dB, an on-chip loss of 5.4 dB, a 3-dB bandwidth of 4.2 nm, a bar-port extinction of 15.0 dB, and a cross-port extinction of 23.0 dB, all in 16-ch average. An average trimming power for the bar states and an average switching power for the cross states are 3.8 mW (σ = 2.3 mW) and 15.6 mW (σ = 2.1 mW), respectively. The wavelength dependence of the spectral responses and the resonant effect from the apodization are discussed in detail to show how to further improve the spectral performance.