InP/InGaAsP Flattened Ring Lasers With Low-Loss Etched Beam Splitters

Compact flattened InP/InGaAsP multiquantum-well (MQW) resonators based on etched beam splitters (EBS) with 300- to 800-nm gaps and circumferences of 30-300 μm are demonstrated. Comparison of the EBS coupler reflection and transmission to 3-D finite-difference time-domain (FDTD) simulations shows good agreement in the wider EBS gap devices. Lasing is observed in 90-, 150-, and 300-μm length rings at threshold currents of 15, 14, and 29 mA, respectively.