Cryogenic VCSEL microwave-optical model for laser frequency response prediction and e-h recombination lifetime analysis

Cryogenic vertical-cavity surface-emitting lasers (VCSELs) for high-speed computing and energy-efficient data links have recently received considerable interest due to the microcavity laser bandwidth enhancement at low operating power. In this work, microwave on-wafer measurements of VCSELs for frequencies up to 50 GHz are performed over temperatures down to 82 K. Subsequently, we applied parasitic de-embedding techniques to develop a microwave-optical laser model. Based on the bias-dependent measurement of laser frequency responses and laser model, the photon and electron-hole (e-h) recombination lifetimes are accurately extracted to explain the physics of laser bandwidth enhancement and the behavior of resonances. Finally, we demonstrate that the VCSEL can deliver a modulated bandwidth of >60 GHz at a low operating current, I = 3 mA, for delivering >120 Gb/s non-return-to-zero data to establish an energy-efficient optical link at 82 K.