Electrically Switchable Photonic Molecule Laser

TL;DR

This paper demonstrates electrically controlled coherent coupling in terahertz quantum-cascade laser microdisks, enabling optical switching of coupled modes with potential applications in integrated photonic circuits.

Contribution

It introduces a method for electrical control of mode coupling in photonic molecules made of quantum-cascade microdisks, a novel approach for active photonic device modulation.

Findings

Coherent intercavity coupling achieved up to 40 μm separation.

Optical emission can be switched electrically by modulating one microdisk.

Laser gain shows linear dependence on applied electric field.

Abstract

We have studied the coherent intercavity coupling of the evanescent fields of the whispering gallery modes of two terahertz quantum-cascade lasers implemented as microdisk cavities. The electrically pumped single-mode operating microcavities allow to electrically control the coherent mode coupling for proximity distances of the cavities up to 30-40 \mu\m. The optical emission of the strongest coupled photonic molecule can be perfectly switched by the electrical modulation of only one of the coupled microdisks. The threshold characteristics of the strongest coupled photonic molecule demonstrates the linear dependence of the gain of a quantum-cascade laser on the applied electric field.