Design and Demonstration of an O-Band InP Monolithically Integrated SOA-Based Broadcast and Select Optical Space Switch

With the increasing requirements of optical interconnects in high-performance artificial intelligence compute clusters, optical space switches could provide a fast and efficient alternative to existing power-hungry electronic network switches. This work shows the design, fabrication and characterization of the first fully InP monolithically integrated, O-band compatible space switch, using semiconductor optical amplifiers configured in a broadcast-and-select topology. We demonstrate an average fiber-to-fiber insertion loss of 10 dB per optical path and an optical bandwidth of 37 nm. Since no gain saturation is observed, the OSNR is measured up to 47.5 dB. As a result, the transmission experiments show good performance with no distortion and a power penalty below 0.7 dB at 10 Gb/s NRZ, 100 GB/s PAM-4 and using a 100 G LWDM LR4 commercial transceiver with 4 wavelength channels at 25 Gb/s NRZ. We discuss the scalability of the broadcast-and-select topology and demonstrate the viability of an 8x8 space switch, which shows comparable results to the 4x4 space switch with a negligible power penalty for the majority of the LWDM channels. Based on the results, we discuss the prospects for future designs and highlight potential scalability to larger switches.