Single mode lasing in MMI coupled square semiconductor ring resonators

This work reports the spectral characteristics of coupled-square ring semiconductor resonators. A simple square cavity showed complex peak lasing patterns with a broad envelope. For a single mode operation, the square ring cavities coupled with multimode interferometers are proposed and fabricated using the epitaxial layers of 1.55 μm center wavelength InGaAsP-InP multiple quantum wells. A stable single spectral lasing mode was obtained in the proposed multimode interferometer square cavities and the lasing characteristics with power and temperature were also presented.