{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,6]],"date-time":"2026-03-06T08:06:37Z","timestamp":1772784397772,"version":"3.50.1"},"reference-count":31,"publisher":"MDPI AG","issue":"24","license":[{"start":{"date-parts":[[2023,12,14]],"date-time":"2023-12-14T00:00:00Z","timestamp":1702512000000},"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>Mid-infrared optics require optical coatings composed of high- and low-refractive-index dielectric layers for the design of optical mirrors, filters, and anti-reflection coatings. However, there are not many technologies for depositing a material with a refractive index of less than 2 and a low loss in the mid-infrared region. Here, we present a unique deposition method of crosslinked polyethylene thin film for mid-IR optical filter design. Polyethylene has a refractive index of 1.52 in the mid-infrared region and a small number of absorption peaks, so it is useful for making optical filters in the mid-infrared region. Only 1 keV of energy is required to crosslink the entire film by irradiating an electron beam while depositing polyethylene. In addition, crosslinked polyethylene thin film has high mechanical strength, so there is no cracking or peeling when used with germanium. This allows for the use of crosslinked polyethylene as a low refractive index for mid-infrared optical coating.<\/jats:p>","DOI":"10.3390\/s23249810","type":"journal-article","created":{"date-parts":[[2023,12,18]],"date-time":"2023-12-18T11:28:07Z","timestamp":1702898887000},"page":"9810","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Novel Deposition Method of Crosslinked Polyethylene Thin Film for Low-Refractive-Index Mid-Infrared Optical Coatings"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6960-7140","authenticated-orcid":false,"given":"Taeyoon","family":"Jeon","sequence":"first","affiliation":[{"name":"Applied Physics and Materials Science, California Institute of Technology, 1200 East California Boulevard, MC 200-79, Pasadena, CA 91125, USA"}]},{"given":"Jieun","family":"Myung","sequence":"additional","affiliation":[{"name":"Applied Physics and Materials Science, California Institute of Technology, 1200 East California Boulevard, MC 200-79, Pasadena, CA 91125, USA"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-4037-8643","authenticated-orcid":false,"given":"Changsoon","family":"Choi","sequence":"additional","affiliation":[{"name":"Applied Physics and Materials Science, California Institute of Technology, 1200 East California Boulevard, MC 200-79, Pasadena, CA 91125, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1532-357X","authenticated-orcid":false,"given":"Komron","family":"Shayegan","sequence":"additional","affiliation":[{"name":"Applied Physics and Materials Science, California Institute of Technology, 1200 East California Boulevard, MC 200-79, Pasadena, CA 91125, USA"}]},{"given":"Scott M.","family":"Lewis","sequence":"additional","affiliation":[{"name":"Applied Physics and Materials Science, California Institute of Technology, 1200 East California Boulevard, MC 200-79, Pasadena, CA 91125, USA"}]},{"given":"Axel","family":"Scherer","sequence":"additional","affiliation":[{"name":"Applied Physics and Materials Science, California Institute of Technology, 1200 East California Boulevard, MC 200-79, Pasadena, CA 91125, USA"}]}],"member":"1968","published-online":{"date-parts":[[2023,12,14]]},"reference":[{"key":"ref_1","unstructured":"Pavia, D.L., Lampman, G.M., Kriz, G.S., and Vyvyan, J.R. (2015). Introduction to Spectroscopy, Cengage Learning."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Griffiths, P.R., and De Haseth, J.A. (2007). Fourier Transform Infrared Spectroscopy, Wiley.","DOI":"10.1002\/047010631X"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1533","DOI":"10.1088\/0034-4885\/64\/11\/204","article-title":"Recent progress in quantum cascade lasers and applications","volume":"64","author":"Gmachl","year":"2001","journal-title":"Rep. Prog. Phys."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"68","DOI":"10.1021\/acsphotonics.1c01750","article-title":"Development of a Compact and Robust Mid-Infrared Spectrometer by Using a Silicon\/Air Hyperspectral Filter","volume":"9","author":"Jeon","year":"2022","journal-title":"ACS Photonics"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1038\/s41566-018-0135-2","article-title":"Massively parallel sensing of trace molecules and their isotopologues with broadband subharmonic mid-infrared frequency combs","volume":"12","author":"Muraviev","year":"2018","journal-title":"Nat. Photonics"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"150401","DOI":"10.1063\/1.5097933","article-title":"On-chip mid-infrared and THz frequency combs for spectroscopy","volume":"114","author":"Scalari","year":"2019","journal-title":"Appl. Phys. Lett."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1105","DOI":"10.1126\/science.aas9768","article-title":"Imaging-based molecular barcoding with pixelated dielectric metasurfaces","volume":"360","author":"Tittl","year":"2018","journal-title":"Science"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"eaaw2871","DOI":"10.1126\/sciadv.aaw2871","article-title":"Angle-multiplexed all-dielectric metasurfaces for broadband molecular fingerprint retrieval","volume":"5","author":"Leitis","year":"2019","journal-title":"Sci. Adv."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"495","DOI":"10.1038\/nphoton.2010.171","article-title":"Mid-infrared photonics in silicon and germanium","volume":"4","author":"Soref","year":"2010","journal-title":"Nat. Photonics"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"99740X","DOI":"10.1117\/12.2237978","article-title":"Refractive index measurement of Ge","volume":"9974","author":"Burnett","year":"2016","journal-title":"Proc. SPIE"},{"key":"ref_11","first-page":"123526","article-title":"High-accuracy; midinfrared (450 cm\u22121 \u2a7d \u03c9 \u2a7d 4000 cm\u22121) refractive index values of silicon","volume":"97","author":"Amirtharaj","year":"2005","journal-title":"J. Appl. Phys."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"224","DOI":"10.1117\/12.439179","article-title":"Measurement of the temperature-dependent refractive index and relative photoelastic constant of zinc sulfide","volume":"4375","author":"Blodgett","year":"2001","journal-title":"Proc. SPIE"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"679","DOI":"10.1007\/s10812-017-0529-9","article-title":"Optical Constants of Zinc Selenide in Visible and Infrared Spectral Ranges","volume":"84","author":"Qi","year":"2017","journal-title":"J. Appl. Spectrosc."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"489","DOI":"10.1364\/OE.20.000489","article-title":"Design and implementation of a sub-nm resolution microspectrometer based on a Linear-Variable Optical Filter","volume":"20","author":"Emadi","year":"2012","journal-title":"Opt. Express"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"115207","DOI":"10.1088\/2053-1591\/ab475a","article-title":"Variations in the linear and nonlinear refractive indices of chalcogenide glass thin films for photonic applications","volume":"6","author":"Musfir","year":"2019","journal-title":"Mater. Res. Express"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"25674","DOI":"10.1364\/OE.25.025674","article-title":"Mid-infrared optical properties of chalcogenide glasses within tin-antimony-selenium ternary system","volume":"25","author":"Lin","year":"2017","journal-title":"Opt. Express"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"197","DOI":"10.1016\/j.mee.2012.02.025","article-title":"Mid-infrared nanoantenna arrays on silicon and CaF2 substrates for sensing applications","volume":"97","author":"Businaro","year":"2012","journal-title":"Microelectron. Eng."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"3343","DOI":"10.1088\/0022-3727\/40\/11\/013","article-title":"The determination of infrared optical constants of rare earth fluorides by classical Lorentz oscillator model","volume":"40","author":"Su","year":"2007","journal-title":"J. Phys. Appl. Phys."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"7091","DOI":"10.1364\/AO.37.007091","article-title":"Refractive indices and extinction coefficients of polymers for the mid-infrared region","volume":"37","author":"Wang","year":"1998","journal-title":"Appl. Opt."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"7496","DOI":"10.1021\/ma000094x","article-title":"Spin Coating and Characterization of Thin High-Density Polyethylene Films","volume":"34","author":"Mellbring","year":"2001","journal-title":"Macromolecules"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"437","DOI":"10.1016\/0042-207X(68)90336-9","article-title":"Thermal degradation of polyethylene and polytetrafluoroethylene during vacuum evaporation","volume":"18","author":"Iuff","year":"1968","journal-title":"Vacuum"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1161","DOI":"10.1002\/pen.760351406","article-title":"Radiation crosslinking of polyethylene with electron beam at different temperature","volume":"35","author":"Qu","year":"1995","journal-title":"Polym. Eng. Sci."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"6115","DOI":"10.1016\/S0032-3861(98)00075-5","article-title":"Surface crosslinking of polyethylene by electron beam irradiation in air","volume":"39","author":"Tretinnikov","year":"1998","journal-title":"Polymer"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"557","DOI":"10.1016\/S0142-9418(01)00124-6","article-title":"Polyethylene characterization by FTIR","volume":"21","author":"Gulmine","year":"2002","journal-title":"Polym. Test."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"608","DOI":"10.1002\/sia.2611","article-title":"Surface characterization of plasma-modified polyethylene by contact angle experiments and ATR-FTIR spectroscopy","volume":"40","author":"Morent","year":"2008","journal-title":"Surf. Interface Anal."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2103153","DOI":"10.1002\/adfm.202103153","article-title":"Optical Microelectromechanical Systems Technologies for Spectrally Adaptive Sensing and Imaging","volume":"32","author":"Martyniuk","year":"2022","journal-title":"Adv. Funct. Mater."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"78","DOI":"10.1103\/PhysRev.49.78","article-title":"Thermionic emission from tungsten and thoriated tungsten filaments","volume":"49","author":"Nottingham","year":"1936","journal-title":"Phys. Rev."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"92","DOI":"10.1002\/sca.20000","article-title":"CASINO V2.42\u2014A Fast and Easy-to-use Modeling Tool for Scanning Electron Microscopy and Microanalysis Users","volume":"29","author":"Drouin","year":"2007","journal-title":"Scanning"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"6588","DOI":"10.1039\/D0TB00681E","article-title":"Vapor-deposited functional polymer thin films in biological applications","volume":"8","author":"Khlyustova","year":"2020","journal-title":"J. Mater. Chem. B"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"5811","DOI":"10.1021\/acsami.2c18989","article-title":"In Situ Polymerized MXene\/Polypyrrole\/Hydroxyethyl Cellulose-Based Flexible Strain Sensor Enabled by Machine Learning for Handwriting Recognition","volume":"15","author":"Yang","year":"2023","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"022001","DOI":"10.1088\/2053-1591\/ac4aa1","article-title":"A review on thin films, conducting polymers as sensor devices","volume":"9","author":"Elanjeitsenni","year":"2022","journal-title":"Mater. Res. Express"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/24\/9810\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T21:38:28Z","timestamp":1760132308000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/24\/9810"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,12,14]]},"references-count":31,"journal-issue":{"issue":"24","published-online":{"date-parts":[[2023,12]]}},"alternative-id":["s23249810"],"URL":"https:\/\/doi.org\/10.3390\/s23249810","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,12,14]]}}}