{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,24]],"date-time":"2026-03-24T21:18:26Z","timestamp":1774387106829,"version":"3.50.1"},"reference-count":22,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2016,2,17]],"date-time":"2016-02-17T00:00:00Z","timestamp":1455667200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The need for highly performing and stable methods for mid-IR molecular sensing and metrology pushes towards the development of more and more compact and robust systems. Among the innovative solutions aimed at answering the need for stable mid-IR references are crystalline microresonators, which have recently shown excellent capabilities for frequency stabilization and linewidth narrowing of quantum cascade lasers with compact setups. In this work, we report on the first system for mid-IR high-resolution spectroscopy based on a quantum cascade laser locked to a CaF2 microresonator. Electronic locking narrows the laser linewidth by one order of magnitude and guarantees good stability over long timescales, allowing, at the same time, an easy way for finely tuning the laser frequency over the molecular absorption line. Improvements in terms of resolution and frequency stability of the source are demonstrated by direct sub-Doppler recording of a molecular line.<\/jats:p>","DOI":"10.3390\/s16020238","type":"journal-article","created":{"date-parts":[[2016,2,18]],"date-time":"2016-02-18T22:19:47Z","timestamp":1455833987000},"page":"238","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["Tunable Microcavity-Stabilized Quantum Cascade Laser for Mid-IR High-Resolution Spectroscopy and Sensing"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8471-2803","authenticated-orcid":false,"given":"Simone","family":"Borri","sequence":"first","affiliation":[{"name":"CNR-INO \u2013 Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy"},{"name":"LENS \u2013 European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy"},{"name":"INFN \u2013 Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino, FI, Italy"}]},{"given":"Mario","family":"Siciliani de Cumis","sequence":"additional","affiliation":[{"name":"CNR-INO \u2013 Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy"},{"name":"INRIM \u2013 Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135 Torino, Italy"}]},{"given":"Giacomo","family":"Insero","sequence":"additional","affiliation":[{"name":"CNR-INO \u2013 Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy"},{"name":"LENS \u2013 European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8338-748X","authenticated-orcid":false,"given":"Saverio","family":"Bartalini","sequence":"additional","affiliation":[{"name":"CNR-INO \u2013 Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy"},{"name":"LENS \u2013 European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy"}]},{"given":"Pablo","family":"Cancio Pastor","sequence":"additional","affiliation":[{"name":"CNR-INO \u2013 Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy"},{"name":"LENS \u2013 European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2047-1611","authenticated-orcid":false,"given":"Davide","family":"Mazzotti","sequence":"additional","affiliation":[{"name":"CNR-INO \u2013 Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy"},{"name":"LENS \u2013 European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7955-6647","authenticated-orcid":false,"given":"Iacopo","family":"Galli","sequence":"additional","affiliation":[{"name":"CNR-INO \u2013 Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy"},{"name":"LENS \u2013 European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy"}]},{"given":"Giovanni","family":"Giusfredi","sequence":"additional","affiliation":[{"name":"CNR-INO \u2013 Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy"},{"name":"LENS \u2013 European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy"}]},{"given":"Gabriele","family":"Santambrogio","sequence":"additional","affiliation":[{"name":"CNR-INO \u2013 Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy"},{"name":"LENS \u2013 European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy"},{"name":"INRIM \u2013 Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135 Torino, Italy"}]},{"given":"Anatoliy","family":"Savchenkov","sequence":"additional","affiliation":[{"name":"OEwaves Inc., 465 North Halstead Street, Suite 140, Pasadena, CA 91107, USA"}]},{"given":"Danny","family":"Eliyahu","sequence":"additional","affiliation":[{"name":"OEwaves Inc., 465 North Halstead Street, Suite 140, Pasadena, CA 91107, USA"}]},{"given":"Vladimir","family":"Ilchenko","sequence":"additional","affiliation":[{"name":"OEwaves Inc., 465 North Halstead Street, Suite 140, Pasadena, CA 91107, USA"}]},{"given":"Naota","family":"Akikusa","sequence":"additional","affiliation":[{"name":"Development Bureau Laser Device R &amp; D Group, Hamamatsu Photonics KK, Shizuoka 434-8601, Japan"}]},{"given":"Andrey","family":"Matsko","sequence":"additional","affiliation":[{"name":"OEwaves Inc., 465 North Halstead Street, Suite 140, Pasadena, CA 91107, USA"}]},{"given":"Lute","family":"Maleki","sequence":"additional","affiliation":[{"name":"OEwaves Inc., 465 North Halstead Street, Suite 140, Pasadena, CA 91107, USA"}]},{"given":"Paolo","family":"De Natale","sequence":"additional","affiliation":[{"name":"CNR-INO \u2013 Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy"},{"name":"LENS \u2013 European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy"},{"name":"INFN \u2013 Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino, FI, Italy"}]}],"member":"1968","published-online":{"date-parts":[[2016,2,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Galli, I., Bartalini, S., Borri, S., Cancio Pastor, P., Mazzotti, D., De Natale, P., and Giusfredi, G. (2011). Molecular Gas Sensing below Parts per Trillion: Radiocarbon-Dioxide Optical Detection. Phys. Rev. Lett., 107.","DOI":"10.1103\/PhysRevLett.107.270802"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1919","DOI":"10.1103\/PhysRevLett.86.1919","article-title":"Search for Exchange-Antisymmetric States for Spin-0 Particles at the 10\u221211 Level","volume":"86","author":"Mazzotti","year":"2001","journal-title":"Phys. Rev. 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