Mid-IR single- and dual-electro-optic comb generation with an ultrafast modulator

Gia-Long Ngo; Luca Lucia; Stefano Pirotta; Mario Malerba; Lianhe H Li; Stefano Barbieri; Victor Merupo; Edmund H Linfield; Benoit Darquié; Jean-Michel Manceau; Adel Bousseksou; Raffaele Colombelli

arXiv · 2607.03317

Mid-IR single- and dual-electro-optic comb generation with an ultrafast modulator

Gia-Long Ngo·Luca Lucia·Stefano Pirotta·Mario Malerba·Lianhe H Li·Stefano Barbieri·Victor Merupo·Edmund H Linfield·Benoit Darquié·Jean-Michel Manceau·Adel Bousseksou·Raffaele Colombelli

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Abstract

Mid-infrared (mid-IR) frequency combs are powerful tools for molecular sensing, industrial monitoring, and precision spectroscopy, yet their development beyond 5 um remains limited. Electro-optic modulation offers a promising path toward compact, agile comb generation, but extending this approach into the mid-infrared has been hindered by the lack of practical, high-performance modulators. Here we present an approach that leads to efficient generation of mid infrared frequency combs around 9 um, by employing ultrafast, room temperature, free space electro optic intensity modulators. By driving a single modulator with short electrical pulse trains, we realize both single- and dual-comb operation from a continuous-wave quantum cascade laser, providing a compact and versatile platform for mid-IR spectroscopy. This scheme produces combs with tunable repetition rates down to the megahertz range with direct observation on an electrical spectrum analyzer without any interferometer. As a proof of concept, we perform single- and dual-comb spectroscopy of a germanium etalon and an ammonia cell, achieving resolution far beyond that of conventional Fourier-transform infrared (FTIR) spectrometers and highlighting the potential of this approach for precise measurements in the long-wavelength molecular-fingerprint region. These results establish high-performance mid-IR modulators as a promising route toward practical, energy-efficient frequency-comb systems for sensing and spectroscopy.

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Gia-Long Ngo, Luca Lucia, Stefano Pirotta, Mario Malerba, Lianhe H Li, Stefano Barbieri, Victor Merupo, Edmund H Linfield, Benoit Darquié, Jean-Michel Manceau, Adel Bousseksou, Raffaele Colombelli. 2026-07-03. Mid-IR single- and dual-electro-optic comb generation with an ultrafast modulator. https://arxiv.org/abs/2607.03317

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