Microcavity VCSELs for cryogenic single-mode optical data link to achieve 28 fJ/bit at 136 Gbps

We report on the development of microcavity vertical-cavity surface-emitting lasers (VCSELs) for cryogenic operation based on a 1/2-λ cavity and a <2-μm oxide aperture. Optical spectra show single-mode laser operation with a superior side-mode suppression ratio of 41 dB (3 K) and 36 dB (40 K) up to 8 mA. The microcavity laser operated at low bias current, I = 1.5 mA, demonstrates a 136 Gbps optical link at 40 K to achieve an ultralow energy consumption of 28 fJ/bit. Thus, high-speed cryogenic microcavity VCSELs are a cost-effective solution to deliver a higher energy-efficient optical data link.