Frequency combs induced by optical feedback and harmonic order tunability in quantum cascade lasers

This study investigates the interaction between frequency combs and optical feedback effects in Quantum Cascade Lasers (QCLs). The theoretical analysis reveals new phenomena arising from the interplay between comb generation and feedback. By considering the bias current corresponding to free-running...

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Main Authors: Carlo Silvestri, Xiaoqiong Qi, Thomas Taimre, Aleksandar D. Rakić
Format: Article
Language:English
Published: AIP Publishing LLC 2023-11-01
Series:APL Photonics
Online Access:http://dx.doi.org/10.1063/5.0164597
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author Carlo Silvestri
Xiaoqiong Qi
Thomas Taimre
Aleksandar D. Rakić
author_facet Carlo Silvestri
Xiaoqiong Qi
Thomas Taimre
Aleksandar D. Rakić
author_sort Carlo Silvestri
collection DOAJ
description This study investigates the interaction between frequency combs and optical feedback effects in Quantum Cascade Lasers (QCLs). The theoretical analysis reveals new phenomena arising from the interplay between comb generation and feedback. By considering the bias current corresponding to free-running single mode emission, the introduction of optical feedback can trigger the generation of frequency combs, including both fundamental and harmonic combs. This presents opportunities to extend the comb region and generate harmonic frequency combs with different orders through optimization of external cavity parameters, such as losses and length. Furthermore, this study demonstrates that optical feedback can selectively tune the harmonic order of a pre-existing free-running comb by adjusting the external cavity length, particularly for feedback ratios around 1%, which are readily achievable in experimental setups. Under strong feedback conditions (Acket parameter C > 4.6), mixed states emerge, displaying the features of both laser and external cavity dynamics. While this study is predominantly centered on terahertz QCLs, we have also confirmed that the described phenomena occur when utilizing mid-infrared QCL parameters. This work establishes a connection between comb technology and the utilization of optical feedback, providing new avenues for exploration and advancement in the field. In fact, the novel reported phenomena open a pathway toward new methodologies across various domains, such as the design of tunable comb sources, hyperspectral imaging, multi-mode coherent sensing, and multi-channel communication.
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spelling doaj.art-bbecdbbcaefd4d84bc59350661421ee82023-12-04T17:13:19ZengAIP Publishing LLCAPL Photonics2378-09672023-11-01811116102116102-1010.1063/5.0164597Frequency combs induced by optical feedback and harmonic order tunability in quantum cascade lasersCarlo Silvestri0Xiaoqiong Qi1Thomas Taimre2Aleksandar D. Rakić3School of Electrical Engineering and Computer Science, The University of Queensland, Brisbane, QLD 4072, AustraliaSchool of Electrical Engineering and Computer Science, The University of Queensland, Brisbane, QLD 4072, AustraliaSchool of Mathematics and Physics, The University of Queensland, Brisbane, QLD 4072, AustraliaSchool of Electrical Engineering and Computer Science, The University of Queensland, Brisbane, QLD 4072, AustraliaThis study investigates the interaction between frequency combs and optical feedback effects in Quantum Cascade Lasers (QCLs). The theoretical analysis reveals new phenomena arising from the interplay between comb generation and feedback. By considering the bias current corresponding to free-running single mode emission, the introduction of optical feedback can trigger the generation of frequency combs, including both fundamental and harmonic combs. This presents opportunities to extend the comb region and generate harmonic frequency combs with different orders through optimization of external cavity parameters, such as losses and length. Furthermore, this study demonstrates that optical feedback can selectively tune the harmonic order of a pre-existing free-running comb by adjusting the external cavity length, particularly for feedback ratios around 1%, which are readily achievable in experimental setups. Under strong feedback conditions (Acket parameter C > 4.6), mixed states emerge, displaying the features of both laser and external cavity dynamics. While this study is predominantly centered on terahertz QCLs, we have also confirmed that the described phenomena occur when utilizing mid-infrared QCL parameters. This work establishes a connection between comb technology and the utilization of optical feedback, providing new avenues for exploration and advancement in the field. In fact, the novel reported phenomena open a pathway toward new methodologies across various domains, such as the design of tunable comb sources, hyperspectral imaging, multi-mode coherent sensing, and multi-channel communication.http://dx.doi.org/10.1063/5.0164597
spellingShingle Carlo Silvestri
Xiaoqiong Qi
Thomas Taimre
Aleksandar D. Rakić
Frequency combs induced by optical feedback and harmonic order tunability in quantum cascade lasers
APL Photonics
title Frequency combs induced by optical feedback and harmonic order tunability in quantum cascade lasers
title_full Frequency combs induced by optical feedback and harmonic order tunability in quantum cascade lasers
title_fullStr Frequency combs induced by optical feedback and harmonic order tunability in quantum cascade lasers
title_full_unstemmed Frequency combs induced by optical feedback and harmonic order tunability in quantum cascade lasers
title_short Frequency combs induced by optical feedback and harmonic order tunability in quantum cascade lasers
title_sort frequency combs induced by optical feedback and harmonic order tunability in quantum cascade lasers
url http://dx.doi.org/10.1063/5.0164597
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