arXiv subjects

Deborah L. Sivco

Publications and source records attributed to Deborah L. Sivco.

4 recordsLinked to original sources

arXiv2025

Amplified Feedback and Spontaneous Emission Injection in Quantum Cascade Ring Laser Systems

Ring lasers exhibit rich operational regimes such as unidirectional, bidirectional, or bistable operation. The two-mode dynamics of the counter-propagating modes - clockwise (CW) and counterclockwise (CCW) and their selection, have gained attention in the mid-infrared; however, the underlying switching mechanism has been largely unexplored. Previously, we experimentally demonstrated robust and deterministic mode selection in a ring quantum cascade laser (QCL) with an active outcoupling waveguide. Here, we apply the Lang-Kobayashi framework to our system to model the effects of spontaneous emission in the waveguide arms as well as amplified optical feedback from the facets on the mechanics of mode switching. We find that coherent feedback from facet reflections agrees upwards of 93\% with the experimental behavior, indicating that amplified feedback is the dominant mechanism driving the mode selection dynamics.

physics.optics↗

arXiv2023

Photonic molecule based on coupled ring quantum cascade lasers

Photonic molecules - particular systems composed of coupled optical resonators - emulate the behavior of complex physical systems exhibiting discrete energy levels. In this work, we present a novel photonic molecule composed of two strongly coupled, mid-infrared ring quantum cascade lasers. We explore both experimentally and numerically the key features of the photonic molecule such as the energy level splitting of bonding and antibonding supermodes. Due to the large size of the resonators, the energy splitting results in bands containing tens of modes. Each of these modes is furthermore doubly degenerate with respect to the direction of propagation, namely clockwise and counterclockwise. We explore several methods to carefully break these symmetries of the system in a controlled manner by introducing spatial and temporal asymmetries in the pumping scheme of the ring lasers. By employing these techniques, we achieve a high degree of precision in the dynamic control of the photonic molecule. Owing to their inherent suitability for on-chip integration, this new class of devices may enable applications as varied as novel mid-infrared sensors or a rich playground for studying non-Hermitian photonics and quantum optics with quantum cascade lasers.

physics.optics↗

arXiv2022

Unidirectional mode selection in bistable quantum cascade ring lasers

Ideal ring resonators are characterized by travelling-wave counterpropagating 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.

physics.optics↗

arXiv1998

High-Power Directional Emission from Microlasers with Chaotic Resonators

High-power and highly directional semiconductor cylinder-lasers based on an optical resonator with deformed cross section are reported. In the favorable directions of the far-field, a power increase of up to three orders of magnitude over the conventional circularly symmetric lasers was obtained. A "bow-tie"-shaped resonance is responsible for the improved performance of the lasers in the higher range of deformations, in contrast to "whispering-gallery"-type modes of circular and weakly deformed lasers. This resonator design, although demonstrated here in midinfrared quantum-cascade lasers, should be applicable to any laser based on semiconductors or other high-refractive index materials.

cond-mat.mes-hall↗