Cryo-VCSELs Operated at 2.8 K and 40 K With Record Bandwidth, Power, and Linearity for Optical Data Links in Quantum Computing

Cryogenic CMOS controller and Superconducting processors for scalable Quantum Computing are pivotal technological advancements for cryogenic computing. However, energy-efficient data link from cryogenic operations to room temperature applications remains to be developed. In this work, we report on the development of high-speed Cryogenic VCSEL with material design of gain-cavity alignment around 40 K and oxide-aperture of
$6~\mu $
m operated from 2.8 K to 300 K. In addition, we have established on-wafer cryogenic microwave electrical and optical probing system for performing accurate measurement calibration. Cryo-VCSELs at 2.8 K and 40 K with the record Laser Pout >13 mW, high L-I linearity up to I/I
$_{\mathrm {th}} \gt 125$
and bandwidth f
$_{\mathrm {-3dB}} \gt 50$
GHz are measured. Furthermore, these devices demonstrate high-speed optical data link of NRZ =64 Gb/s with TDEC <3 dB and 112 Gb/s PAM-4 with TDECQ =2.56 dB at 7 mA operating current.