title: Low-Loss Coupling of Quantum Cascade Lasers into Hollow-Core Waveguides with Single-Mode Output in the 3.7-7.6 μm Spectral Range.
abstract: We demonstrated low-loss and single-mode laser beam delivery through hollow-core waveguides (HCWs) operating in the 3.7-7.6 μm spectral range. The employed HCWs have a circular cross section with a bore diameter of 200 μm and metallic/dielectric internal coatings deposited inside a glass capillary tube. The internal coatings have been produced to enhance the spectral response of the HCWs in the range 3.5-12 µm. We demonstrated Gaussian-like outputs throughout the 4.5-7.6 µm spectral range. A quasi single-mode output beam with only small beam distortions was achieved when the wavelength was reduced to 3.7 μm. With a 15-cm-long HCW and optimized coupling conditions, we measured coupling efficiencies of >88% and transmission losses of <1 dB in the investigated infrared spectral range.
authors.affiliation: Dipartimento Interateneo di Fisica, Università degli studi di Bari Aldo Moro e Politecnico di Bari, Via Amendola 173, Bari I-70126, Italy. pietro.patimisco@uniba.it.|Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA. pietro.patimisco@uniba.it.
authors.forename: Pietro
authors.initials: P
authors.lastname: Patimisco
authors.affiliation: Dipartimento Interateneo di Fisica, Università degli studi di Bari Aldo Moro e Politecnico di Bari, Via Amendola 173, Bari I-70126, Italy. angelo.sampaolo@uniba.it.|Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA. angelo.sampaolo@uniba.it.
authors.forename: Angelo
authors.initials: A
authors.lastname: Sampaolo
authors.affiliation: National Institute for Laser, Plasma and Radiation Physics Laser Metrology and Standardization Laboratory 409 Atomistilor, 077125 Magurele-Bucharest, Romania. laura.mihai@inflpr.ro.
authors.forename: Laura
authors.initials: L
authors.lastname: Mihai
authors.affiliation: Dipartimento Interateneo di Fisica, Università degli studi di Bari Aldo Moro e Politecnico di Bari, Via Amendola 173, Bari I-70126, Italy. marilena.giglio@uniba.it.
authors.forename: Marilena
authors.initials: M
authors.lastname: Giglio
authors.affiliation: Opto-Knowledge Systems, Inc. (OKSI), 19805 Hamilton Ave., Torrance, CA 90502-1341, USA. jason@oksi.com.
authors.forename: Jason
authors.initials: J
authors.lastname: Kriesel
authors.affiliation: National Institute for Laser, Plasma and Radiation Physics Laser Metrology and Standardization Laboratory 409 Atomistilor, 077125 Magurele-Bucharest, Romania. dan.sporea@inflpr.ro.
authors.forename: Dan
authors.initials: D
authors.lastname: Sporea
authors.affiliation: Dipartimento Interateneo di Fisica, Università degli studi di Bari Aldo Moro e Politecnico di Bari, Via Amendola 173, Bari I-70126, Italy. gaetano.scamarcio@uniba.it.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Scamarcio
authors.affiliation: Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA. fkt@rice.edu.
authors.forename: Frank K
authors.initials: FK
authors.lastname: Tittel
authors.affiliation: Dipartimento Interateneo di Fisica, Università degli studi di Bari Aldo Moro e Politecnico di Bari, Via Amendola 173, Bari I-70126, Italy. vincenzoluigi.spagnolo@poliba.it.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Spagnolo
keywords: hollow-core waveguide; optical coupling; quantum cascade laser; single-mode output