|
Optical switch networks based on silicon photonics can provide high bandwidth, low latency, low power, and low cost interconnect fabrics for datacenter, cloud, and high-performance computing by eliminating the pin-constrained electronic switches and the multiple electrical-optical conversions necessary in traditional networks. Silicon photonics is also compatible with wavelength division multiplexing (WDM) allowing simultaneous routing of large bandwidth data streams. Adoption of photonic switches requires scaling to large port counts compared to current 4x4 and 8x8 demonstrations. For example, a 64-port switch implemented using thirty-two 4x4 and four 16x16 switches will be limited by losses in numerous subcomponents, including optical couplers, waveguide propagation losses, waveguide crossings, and phase shifters. To enable viable optical-link-loss budgets requires incorporation of optical gain in addition to improved efficiency in all subcomponents. We have developed a silicon photonic switch platform with integrated gain based on a carrier with active photonics. Optical switches are monolithically integrated into photonic carrier while semiconductor optical amplifiers (SOAs) and CMOS drive ICs are flip-chip attached. We demonstrated non-blocking 4x4 Si photonic switches with < 3-dB on-chip loss and < -20 dB crosstalk with about 4ns switching time. Photonic carriers and 4-channel SOA arrays were co-designed with custom precision packaging features enabling flip-chip bonding with high accuracy. The photonic carrier incorporates low-loss SiN waveguides with inverse taper structures for efficient coupling to/from the SOA arrays and off-carrier coupling. Photonic carriers with integrated 4-channel SOA arrays were fabricated achieving over 10 dB gain and demonstrating error-free 4x25-Gb/s WDM links for all 4 channels.
|
