Abstract

We show that back reflection from the cleaved output waveguide termination in single-output Y-junction ring lasers has a deleterious effect on the light output by promoting lasing in the non-output-coupled direction. This effect is minimized by tilting the output waveguide about the ring axis by an angle θ. Devices (150-µm radius × 4-µm waveguide) with tilt angles θ = 0°, 5°, and 10° were fabricated. Tilting the laser by 10° increases the cw output power tenfold. Control of the reflection feedback to promote unidirectional lasing is also shown for dual-output ring lasers having separately contacted waveguide extensions that can be biased to control the reflection feedback or to act as photodetectors. Increasing the reflection feedback at one ring output alters the direction of ring lasing and affects the other ring output. Such controlled feedback will allow the development of unidirectional ring lasers.

© 1992 Optical Society of America