Polarization and Wavelength Performance Improvement in Large-Scale Silicon Photonics Switches

We review our recent results in multi-port strictly non-blocking optical switches based on silicon photonics. Silicon photonics switches are one of the most important devices to realize future datacenters capable of processing a large amount of data with high efficiency. This is because silicon photonics enables fast (ns - μs) switching, dense integration with high uniformity, low power consumption, and mass production leading to low cost. Thus far, we demonstrated switching, all-paths transmission, and fully-loaded operation of up to 32 input ports × 32 output ports silicon photonics switches. The remaining challenges for practical applications are polarization insensitivity and broadband operation. Regarding the polarization-insensitivity, we presented the non-duplicated polarization-diversity 32 × 32 switch with SiN over path waveguides and demonstrated polarization-insensitive operation in limited paths. Regarding the broadband operation, we achieved ∼90 nm bandwidth for −30 dB crosstalk with polarization-insensitivity in the 8 × 8 switch. We review these, and then discuss how to achieve a large port count (>32 × 32), polarization-insensitivity, and broadband operation simultaneously. Moreover, to broaden the range of applications, integration with wavelength filters and expanding operating wavelengths are important. We demonstrated hybrid integration with the silica platform that is suitable for wavelength filters and the 8 × 8 switch operating in the O-band.