Membrane-Mediated Conversion of Near-Infrared Amplitude Modulation into the Self-Mixing Signal of a Terahertz Quantum Cascade Laser

Membrane-Mediated Conversion of Near-Infrared Amplitude Modulation into the Self-Mixing Signal of a Terahertz Quantum Cascade Laser

A platform for converting near-infrared (NIR) laser power modulation into the self-mixing (SM) signal of a quantum cascade laser (QCL) operating at terahertz (THz) frequencies is introduced. This approach is based on laser feedback interferometry (LFI) with a THz QCL using a metal-coated silicon nit...

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Bibliographic Details
Main Authors: Paolo Vezio, Andrea Ottomaniello, Leonardo Vicarelli, Mohammed Salih, Lianhe Li, Edmund Linfield, Paul Dean, Virgilio Mattoli, Alessandro Pitanti, Alessandro Tredicucci
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Photonics
Subjects:
quantum cascade lasers
laser feedback interferometry
self-mixing
terahertz
signal conversion
optomechanics
Online Access:https://www.mdpi.com/2304-6732/12/3/273
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Summary:A platform for converting near-infrared (NIR) laser power modulation into the self-mixing (SM) signal of a quantum cascade laser (QCL) operating at terahertz (THz) frequencies is introduced. This approach is based on laser feedback interferometry (LFI) with a THz QCL using a metal-coated silicon nitride trampoline membrane resonator as both the external QCL laser cavity and the mechanical coupling element of the two-laser hybrid system. We show that the membrane response can be controlled with high precision and stability both in its dynamic (i.e., piezo-electrically actuated) and static state via photothermally induced NIR laser excitation. The responsivity to nanometric external cavity variations and robustness to optical feedback of the QCL LFI apparatus allows a highly sensitive and reliable transfer of the NIR power modulation into the QCL SM voltage, with a bandwidth limited by the thermal response time of the membrane resonator. Interestingly, a dual information conversion is possible thanks to the accurate thermal tuning of the membrane resonance frequency shift and displacement. Overall, the proposed apparatus can be exploited for the precise opto-mechanical control of QCL operation with advanced applications in LFI imaging and spectroscopy and in coherent optical communication.
ISSN:2304-6732

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