INGAAS-ALGAAS-GAAS STRAINED-LAYER QUANTUM-WELL HETEROSTRUCTURE SQUARE RING LASERS

The processing end optical characteristics of an Ingaas-AlGaAs-GaAs strained-layer quantum-well heterostructure square ring laser (4 mu m width and 50-mu m/side length) with two output waveguides and two narrow physical gap couplers are described. The ridges and the total internal reflection (TIR) mirrors of the square ring lasers are fabricated by two photolithographic steps with a single SiO2 mask and planarized with polyimide such that the TIR mirrors are etched through the active region while the ridge waveguides are not Single longitudinal mode operation is observed with a side mode suppression ratio of 20 dB, Asymmetric characteristics of emission spectra from the two output waveguides demonstrates that the square ring lasers operate in traveling wave modes.