Cryogenic operation of a high speed 850 nm VCSEL with 40.1 GHz modulation bandwidth at 223 K

Efficient and reliable interconnect could be achieved with cryogenic VCSELs. In this work, our home-made 850 nm VCSEL is characterized from 298 K to 223 K. At 223 K, our device exhibits an output power of 6 mW, and achieves a record -3dB bandwidth of 40.1 GHz. The higher laser output power and extended bandwidth of the VCSEL attributes to the reduced junction temperature of 62°C at 223 K.