Unidirectional mode selection in bistable quantum cascade ring lasers

Sara Kacmoli, Deborah L. SIVCO, CLAIRE F. GMACHL

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Ideal ring resonators are characterized by travelling-wave counter-propagating modes, but in practice travelling waves can only be realized under unidirectional operation, which has proved elusive. Here, we have designed and fabricated a monolithic quantum cascade ring laser coupled to an active waveguide that allows for robust, deterministic and controllable unidirectional operation. Spontaneous emission injection through the active waveguide enables dynamical switching between the clockwise and counterclockwise states of the ring laser with as little as 1.6% modulation of the electrical input. We show that this behavior stems from a perturbation in the bistable dynamics of the ring laser. In addition to switching and bistability, our novel coupler design for quantum cascade ring lasers offers an efficient mechanism for outcoupling and light detection.

Original languageEnglish (US)
Pages (from-to)47475-47484
Number of pages10
JournalOptics Express
Issue number26
StatePublished - Dec 19 2022

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics


Dive into the research topics of 'Unidirectional mode selection in bistable quantum cascade ring lasers'. Together they form a unique fingerprint.

Cite this