Active control of emission directionality of semiconductor microdisk lasers

TL;DR

This paper demonstrates a method to actively control the emission directionality and lasing mode of semiconductor microdisk lasers by shaping the optical pump profile, enabling tunable frequency and output direction after fabrication.

Contribution

The study introduces adaptive pumping techniques to selectively excite specific lasing modes in microdisks, allowing dynamic control of emission properties.

Findings

Selective mode suppression achieved with adaptive pumping

Emission pattern varies with cavity shape and roughness

Lasing frequency and direction can be switched externally

Abstract

We demonstrate lasing mode selection in nearly circular semiconductor microdisks by shaping the spatial profile of optical pump. Despite of strong mode overlap, adaptive pumping suppresses all lasing modes except the targeted one. Due to slight deformation of the cavity shape and boundary roughness, each lasing mode has distinct emission pattern. By selecting different mode to be the dominant lasing mode, we can switch both the lasing frequency and the output direction. Such tunability by external pump after the laser is fabricated enhances the functionality of semiconductor microcavity lasers.