Electrically Pumped Coupled Waveguide Lasers by Parity-Time Symmetry

Abstract

We demonstrate single transverse-mode operation of InAs quantum dot (QD) broad-area coupled waveguide lasers enabled by parity-time (PT) symmetric breaking. A novel electrically pumped PT laser operates on waveguide cavity with parallel gain and loss regions. Such counterintuitive waveguide design enables PT symmetric breaking, causing unique mode selection and ultimately enabling single mode operation. By tuning the loss in the loss region of the coupled waveguide cavity, several different PT-symmetric regimes are analyzed theoretically, and the corresponding PT symmetric phase transition is demonstrated experimentally in the coupled waveguide laser.

Anomalies in light scattering

“…In both works, undesired longitudinal modes of microrings have been filtered out to achieve single-mode lasing. A similar method can be utilized to filter transverse modes of multimode cavities as demonstrated in large area microring lasers [127] as well as in stripe lasers [161] and microdisc lasers [162].…”