Quantum Walk Comb in a Dual Waveguide Quantum Cascade Laser

TL;DR

This paper demonstrates an integrated dual waveguide quantum cascade laser that significantly enhances output power and enables tunable quantum walk comb operation through passive waveguide design.

Contribution

It introduces a novel integration of a passive waveguide with a ring QCL to improve power output and control dispersion for quantum walk combs.

Findings

Output power increased by over 100 times to 120 mW.

Quantum walk comb operation achieved in the device.

Dispersion tuning affects comb behavior.

Abstract

Ring quantum cascade lasers (QCLs) proved to be a versatile tool for generating tunable and stable frequency combs in the mid infrared range in the form of quantum walk combs. By homogeneously integrating a racetrack QCL with a passive waveguide, which lays on top of the active region plane and therefore can be designed to be fully independent from the laser geometry, we improve the light outcoupling from the ring by more than 2 orders of magnitude reaching a maximum output power of 120 mW. In addition, we show that it is possible to achieve quantum walk comb operation in the devices under analysis. Finally, we prove that we can change the light dispersion by tuning the parameters of the passive waveguide, with a direct impact on the behavior of the generated comb.