Polarization-Insensitive Flexible-Grid Wavelength-Selective Switch Based on Tapered Couplers and Microring Resonators

A polarization-insensitive flexible-grid wavelength-selective switch using silicon-based double-series coupled microring resonators and polarization splitter-rotators are presented, optimized, and experimentally demonstrated. In the cases of TE and TM polarizations, the transmission spectra with tunable bandwidths are generated at the output ports as long as the phase shifters and double-series coupled microring resonators are rationally controlled. Measurement results show that, as the wavelength-channel spacing Δλ is 0.80 nm, the fabricated device working at TE polarization can have a crosstalk less than −15.01 dB, an extinction ratio greater than 28.11 dB, an in-band ripple smaller than 0.91 dB, and a 3-dB bandwidth ranging from 0.56 to 1.98 nm, while in the case of TM polarization, the corresponding crosstalk and in-band ripple are less than −14.86 and 0.83 dB, extinction ratio is larger than 27.30 dB, and 3-dB bandwidth ranges from 0.57 to 1.96 nm. The response time is measured to be 11.23 μs.