Cryogenic VCSEL microwave-optical model for laser frequency response prediction and <i>e–h</i> recombination lifetime analysis

Abstract

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 &amp;gt;60 GHz at a low operating current, I = 3 mA, for delivering &amp;gt;120 Gb/s non-return-to-zero data to establish an energy-efficient optical link at 82 K.