VCSEL Cavity Loss and Gain Measurement for High-Speed Optical Interconnects

Over 100 Gb/s Four-level Pulse-Amplitude Modulation (PAM4) Vertical-Cavity Surface-Emitting Laser (VCSEL) based optical interconnects require high speed, damped, and low relative intensity noise (RIN) VCSELs. Measurement techniques for intrinsic parameters are essential for optimizing VCSEL designs. The proposed VCSEL cavity round-trip loss and gain coefficient measurement provides the insight of VCSEL distributed Bragg reflectors (DBRs) and quantum well (QW) design. A simple VCSEL cavity model is described and excellent matching between the model and measurement is achieved.