{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,13]],"date-time":"2026-02-13T10:02:15Z","timestamp":1770976935049,"version":"3.50.1"},"reference-count":25,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2016,4,13]],"date-time":"2016-04-13T00:00:00Z","timestamp":1460505600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"COST Action MP1204"},{"name":"Italian research projects PON02 00675"},{"name":"Italian research projects PON02 00576"},{"name":"Italian research projects PON03 \u201cSISTEMA\u201d"},{"name":"Robert Welch Foundation","award":["grant C-0586"],"award-info":[{"award-number":["grant C-0586"]}]},{"name":"NSF ERC MIRTHE"},{"name":"Romanian Space Agency (ROSA)","award":["ECSA project, grant 67\/2013"],"award-info":[{"award-number":["ECSA project, grant 67\/2013"]}]},{"DOI":"10.13039\/501100006595","name":"UEFISCDI","doi-asserted-by":"publisher","award":["contract 8PM\/2010"],"award-info":[{"award-number":["contract 8PM\/2010"]}],"id":[{"id":"10.13039\/501100006595","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>We demonstrated low-loss and single-mode laser beam delivery through hollow-core waveguides (HCWs) operating in the 3.7\u20137.6 \u03bcm spectral range. The employed HCWs have a circular cross section with a bore diameter of 200 \u03bcm 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\u201312 \u00b5m. We demonstrated Gaussian-like outputs throughout the 4.5\u20137.6 \u00b5m spectral range. A quasi single-mode output beam with only small beam distortions was achieved when the wavelength was reduced to 3.7 \u03bcm. With a 15-cm-long HCW and optimized coupling conditions, we measured coupling efficiencies of &gt;88% and transmission losses of &lt;1 dB in the investigated infrared spectral range.<\/jats:p>","DOI":"10.3390\/s16040533","type":"journal-article","created":{"date-parts":[[2016,4,13]],"date-time":"2016-04-13T10:08:06Z","timestamp":1460542086000},"page":"533","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":24,"title":["Low-Loss Coupling of Quantum Cascade Lasers into Hollow-Core Waveguides with Single-Mode Output in the 3.7\u20137.6 \u03bcm Spectral Range"],"prefix":"10.3390","volume":"16","author":[{"given":"Pietro","family":"Patimisco","sequence":"first","affiliation":[{"name":"Dipartimento Interateneo di Fisica, Universit\u00e0 degli studi di Bari Aldo Moro e Politecnico di Bari, Via Amendola 173, Bari I-70126, Italy"},{"name":"Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3790-3767","authenticated-orcid":false,"given":"Angelo","family":"Sampaolo","sequence":"additional","affiliation":[{"name":"Dipartimento Interateneo di Fisica, Universit\u00e0 degli studi di Bari Aldo Moro e Politecnico di Bari, Via Amendola 173, Bari I-70126, Italy"},{"name":"Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3869-1890","authenticated-orcid":false,"given":"Laura","family":"Mihai","sequence":"additional","affiliation":[{"name":"National Institute for Laser, Plasma and Radiation Physics Laser Metrology and Standardization Laboratory 409 Atomistilor, 077125 Magurele-Bucharest, Romania"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2603-7648","authenticated-orcid":false,"given":"Marilena","family":"Giglio","sequence":"additional","affiliation":[{"name":"Dipartimento Interateneo di Fisica, Universit\u00e0 degli studi di Bari Aldo Moro e Politecnico di Bari, Via Amendola 173, Bari I-70126, Italy"}]},{"given":"Jason","family":"Kriesel","sequence":"additional","affiliation":[{"name":"Opto-Knowledge Systems, Inc. (OKSI), 19805 Hamilton Ave., Torrance, CA 90502-1341, USA"}]},{"given":"Dan","family":"Sporea","sequence":"additional","affiliation":[{"name":"National Institute for Laser, Plasma and Radiation Physics Laser Metrology and Standardization Laboratory 409 Atomistilor, 077125 Magurele-Bucharest, Romania"}]},{"given":"Gaetano","family":"Scamarcio","sequence":"additional","affiliation":[{"name":"Dipartimento Interateneo di Fisica, Universit\u00e0 degli studi di Bari Aldo Moro e Politecnico di Bari, Via Amendola 173, Bari I-70126, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2245-7565","authenticated-orcid":false,"given":"Frank","family":"Tittel","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4867-8166","authenticated-orcid":false,"given":"Vincenzo","family":"Spagnolo","sequence":"additional","affiliation":[{"name":"Dipartimento Interateneo di Fisica, Universit\u00e0 degli studi di Bari Aldo Moro e Politecnico di Bari, Via Amendola 173, Bari I-70126, Italy"}]}],"member":"1968","published-online":{"date-parts":[[2016,4,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"6165","DOI":"10.3390\/s140406165","article-title":"Quartz-Enhanced Photoacoustic Spectroscopy: A Review","volume":"14","author":"Patimisco","year":"2014","journal-title":"Sensors"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Gagliardi, G., and Loock, H.P. (2014). Cavity-Enhanced Spectroscopy and Sensing, Springer.","DOI":"10.1007\/978-3-642-40003-2"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"699","DOI":"10.1016\/j.optlaseng.2005.04.015","article-title":"Near- and mid-infrared laser monitoring of industrial processes, environment and security applications","volume":"44","author":"Willer","year":"2006","journal-title":"Opt. Laser. Eng."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Hariharan, P. (1996). Optical Holography, Cambridge University Press.","DOI":"10.1017\/CBO9781139174039"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"859","DOI":"10.1364\/OL.17.000859","article-title":"Flattening of the spatial laser beam profile with low losses and minimal beam divergence","volume":"17","author":"Kermene","year":"1992","journal-title":"Opt. Lett."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"7957","DOI":"10.1364\/AO.46.007957","article-title":"Characterization of mid-infrared single mode fibers as modal filters","volume":"46","author":"Ksendzov","year":"2007","journal-title":"Appl. Opt."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"12529","DOI":"10.1364\/OE.15.012529","article-title":"Infrared single mode chalcogenide glass fiber for Space","volume":"15","author":"Houizot","year":"2007","journal-title":"Opt. Express"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"6120","DOI":"10.3390\/ma7096120","article-title":"Photonic bandgap propagation in all-solid chalcogenide microstructured optical fibers","volume":"7","author":"Caillaud","year":"2014","journal-title":"Materials"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"334","DOI":"10.1364\/OL.32.000334","article-title":"Single-mode microstructured optical fiber for the middle infrared","volume":"32","author":"Butvina","year":"2007","journal-title":"Opt. Lett."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Kriesel, J.M., Hagglund, G.M., Gat, N., Spagnolo, V., and Patimisco, P. (2013). Spatial mode filtering of mid-infrared (mid-IR) laser beams with hollow core fiber optics. Proc. SPIE, 8993.","DOI":"10.1117\/12.2040018"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"113102","DOI":"10.1063\/1.4930893","article-title":"Hollow core waveguide as mid-infrared laser modal beam filter","volume":"118","author":"Patimisco","year":"2015","journal-title":"J. Appl. Phys."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Harrington, J.A. (2004). Infrared Fibers and Their Applications, SPIE.","DOI":"10.1117\/3.540899"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Kriesel, J.M., Gat, N., Bernacki, B.E., Erikson, R.L., Cannon, B.D., Myers, T.L., Bledt, C.M., and Harrington, J.A. (2011). Hollow Core Fiber Optics for Mid-Wave and Long-Wave Infrared Spectroscopy. Proc. SPIE, 8018.","DOI":"10.1117\/12.882840"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3114","DOI":"10.1364\/AO.51.003114","article-title":"Loss and modal properties of Ag\/AgI hollow glass waveguides","volume":"51","author":"Bledt","year":"2012","journal-title":"Appl. Opt."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"4461","DOI":"10.1364\/OL.37.004461","article-title":"Part-per-trillion level SF6 detection using a quartz enhanced photoacoustic spectroscopy-based sensor with single-mode fiber-coupled quantum cascade laser excitation","volume":"37","author":"Spagnolo","year":"2012","journal-title":"Opt. Lett."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1007\/s00340-013-5388-3","article-title":"Mid-infrared fiber-coupled QCL-QEPAS sensor","volume":"112","author":"Spagnolo","year":"2013","journal-title":"Appl. Phys. B"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"28222","DOI":"10.1364\/OE.22.028222","article-title":"A widely-tunable mid-infrared fiber-coupled quartz-enhanced photoacoustic sensor for environmental monitoring","volume":"22","author":"Viciani","year":"2014","journal-title":"Opt. Express"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"195","DOI":"10.1364\/OE.23.000195","article-title":"Single mode mid-IR hollow fibers operating in the range 5.1\u201310.5 \u03bcm","volume":"23","author":"Sampaolo","year":"2015","journal-title":"Opt. Express"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Patimisco, P., Sampaolo, A., Kriesel, J.M., Tittel, F.K., Scamarcio, G., and Spagnolo, V. (2015). Mid-IR quantum cascade laser mode coupling in hollow-core, fiber-optic waveguides with single-mode beam delivery. Proc. SPIE, 9370.","DOI":"10.1117\/12.2078960"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2454","DOI":"10.1117\/1.601768","article-title":"Launch conditions and mode coupling in hollow glass waveguides","volume":"37","author":"Nubling","year":"1998","journal-title":"Opt. Eng."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"255","DOI":"10.1007\/s00340-012-4891-2","article-title":"Coupling external cavity mid-IR quantum cascade lasers with low loss hollow metallic\/dielectric waveguides","volume":"108","author":"Patimisco","year":"2012","journal-title":"Appl. Phys. B"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1329","DOI":"10.3390\/s130101329","article-title":"Low-Loss Hollow Waveguide Fibers for Mid-Infrared Quantum Cascade Laser Sensing Applications","volume":"13","author":"Patimisco","year":"2013","journal-title":"Sensors"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"116","DOI":"10.1109\/JLT.1984.1073590","article-title":"Design theory of dielectric-coated circular metallic waveguides for infrared transmission","volume":"2","author":"Miyagi","year":"1984","journal-title":"J. Lightw. Technol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"6449","DOI":"10.1364\/AO.44.006449","article-title":"Infrared transmissive, hollow plastic waveguides with inner Ag\u2013AgI coatings","volume":"44","author":"George","year":"2005","journal-title":"Appl. Opt."},{"key":"ref_25","unstructured":"Mid-Infrared Optical Fiber, Fiber Patch Cables, and Bundles. Available online: https:\/\/www.thorlabs.com\/newgrouppage9.cfm?objectgroup_id=7062#SingleMode."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/16\/4\/533\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T19:22:12Z","timestamp":1760210532000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/16\/4\/533"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2016,4,13]]},"references-count":25,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2016,4]]}},"alternative-id":["s16040533"],"URL":"https:\/\/doi.org\/10.3390\/s16040533","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2016,4,13]]}}}