title: Tunable Microcavity-Stabilized Quantum Cascade Laser for Mid-IR High-Resolution Spectroscopy and Sensing.
abstract: 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.
authors.affiliation: CNR-INO - Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy. simone.borri@ino.it.|LENS - European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy. simone.borri@ino.it.|INFN - Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino, FI, Italy. simone.borri@ino.it.
authors.forename: Simone
authors.initials: S
authors.lastname: Borri
authors.affiliation: CNR-INO - Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy. m.siciliani@inrim.it.|INRIM - Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135 Torino, Italy. m.siciliani@inrim.it.
authors.forename: Mario
authors.initials: M
authors.lastname: Siciliani de Cumis
authors.affiliation: CNR-INO - Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy. insero@lens.unifi.it.|LENS - European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy. insero@lens.unifi.it.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Insero
authors.affiliation: CNR-INO - Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy. saverio.bartalini@ino.it.|LENS - European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy. saverio.bartalini@ino.it.
authors.forename: Saverio
authors.initials: S
authors.lastname: Bartalini
authors.affiliation: CNR-INO - Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy. pablo.canciopastor@ino.it.|LENS - European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy. pablo.canciopastor@ino.it.
authors.forename: Pablo
authors.initials: P
authors.lastname: Cancio Pastor
authors.affiliation: CNR-INO - Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy. davide.mazzotti@ino.it.|LENS - European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy. davide.mazzotti@ino.it.
authors.forename: Davide
authors.initials: D
authors.lastname: Mazzotti
authors.affiliation: CNR-INO - Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy. iacopo.galli@ino.it.|LENS - European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy. iacopo.galli@ino.it.
authors.forename: Iacopo
authors.initials: I
authors.lastname: Galli
authors.affiliation: CNR-INO - Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy. giovanni.giusfredi@ino.it.|LENS - European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy. giovanni.giusfredi@ino.it.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Giusfredi
authors.affiliation: CNR-INO - Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy. g.santambrogio@inrim.it.|LENS - European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy. g.santambrogio@inrim.it.|INRIM - Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135 Torino, Italy. g.santambrogio@inrim.it.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Santambrogio
authors.affiliation: OEwaves Inc., 465 North Halstead Street, Suite 140, Pasadena, CA 91107, USA. Anatoliy.Savchenkov@oewaves.com.
authors.forename: Anatoliy
authors.initials: A
authors.lastname: Savchenkov
authors.affiliation: OEwaves Inc., 465 North Halstead Street, Suite 140, Pasadena, CA 91107, USA. Danny.Eliyahu@oewaves.com.
authors.forename: Danny
authors.initials: D
authors.lastname: Eliyahu
authors.affiliation: OEwaves Inc., 465 North Halstead Street, Suite 140, Pasadena, CA 91107, USA. vladimir.Ilchenko@oewaves.com.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Ilchenko
authors.affiliation: Development Bureau Laser Device R &amp; D Group, Hamamatsu Photonics KK, Shizuoka 434-8601, Japan. aki@crl.hpk.co.jp.
authors.forename: Naota
authors.initials: N
authors.lastname: Akikusa
authors.affiliation: OEwaves Inc., 465 North Halstead Street, Suite 140, Pasadena, CA 91107, USA. andrey.matsko@oewaves.com.
authors.forename: Andrey
authors.initials: A
authors.lastname: Matsko
authors.affiliation: OEwaves Inc., 465 North Halstead Street, Suite 140, Pasadena, CA 91107, USA. Lute.Maleki@oewaves.com.
authors.forename: Lute
authors.initials: L
authors.lastname: Maleki
authors.affiliation: CNR-INO - Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy. paolo.denatale@ino.it.|LENS - European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy. paolo.denatale@ino.it.|INFN - Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino, FI, Italy. paolo.denatale@ino.it.
authors.forename: Paolo
authors.initials: P
authors.lastname: De Natale
keywords: crystalline resonators; infrared resonator; laser stabilization; quantum cascade lasers; sub-Doppler spectroscopy; whispering gallery mode resonators