Experimental measurement of temperature-dependent sellmeier coefficients and thermo-optic coefficients of polymers in terahertz spectral range

Mumtaz, Muhammad; Mahmood, M. Ahsan; Khan, Sikandar; Zia, M. Aslam; Ahmed, Mushtaq; Ahmad, Izhar

doi:10.1016/j.optmat.2019.03.006

Cited by 8 publications

(2 citation statements)

References 26 publications

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“…The work is ongoing on experimental characterization of the dielectric materials using conventional empirical models compatible with simulation software, notably COMSOL Multiphysics. The FTS dielectric measurements can, in principle, provide a complete dataset for retrieval of temperature-dependent Sellmeier and thermo-optic coefficients of a broadband refractive index model, [35], to furnish accurate finite-element analyses with COMSOL of various quasi-optical components and systems of millimeter-astronomy instruments. More datasets are being derived from our recent measurements and will be reported elsewhere.…”

Section: Dielectric Measurement Resultsmentioning

confidence: 99%

Broadband coated lens solutions for FIR-mm-wave instruments

Shitvov

Savini²,

Hargrave³

et al. 2022

Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI

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This paper presents recent results of ongoing European Space Agency funded program of work aimed at developing large dielectric lenses suitable for future satellite missions, with a particular focus on requirements for CMB polarimetry. Two lens solutions are being investigated: (i) polymer lenses with broadband multi-layer antireflection coatings; (ii) silicon lenses with surface-structured anti-reflection coating represented by directly machined pyramidal features. For each solution, base materials with and without coatings have been optically characterized over a range of temperatures down to ~10 K. Full lens solutions are under manufacture and will be tested in a bespoke large cryo-optical facility.

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Section: Dielectric Measurement Resultsmentioning

confidence: 99%

Broadband coated lens solutions for FIR-mm-wave instruments

Shitvov

Savini²,

Hargrave³

et al. 2022

Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI

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“…Owing to their low refractive index values, fluorinated polymers are sought as the best candidates for developing optical structures as antireflecting, protective, or barrier coatings [ 31 ]. Furthermore, thermo-optic coefficients (TOC) are of critical importance as small changes may affect device performances [ 32 , 33 ]. Razali et al reported on thermo-optical coefficients of two different acrylate, cyclomer, and fluorinated polymers, respectively.…”

Section: Introductionmentioning

confidence: 99%

UV LED Curable Perfluoropolyether (PFPE)-Urethane Methacrylate Transparent Coatings for Photonic Applications: Synthesis and Characterization

et al. 2023

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The contribution aims to bring forth a novel synthesis route in developing transparent UV LED-curable coatings accounting for various exposure options. A selection of perfluoropolyether (PFPE)-urethane methacrylate and acrylate resins, free-radical photo-initiator Omnirad 2100, and two distinct silane-based crosslinking agents were blended under a weight ratio of 75:20:5 (without crosslinker) and 70:15:5:10, respectively. The coatings were cured under a UV LED 4 × 3 matrix light emitting source, in a chamber under a controlled atmosphere, by means of an in-house developed conveyor belt type platform, at different conveyor belt speeds (5, 50, 150, 250, and 500 mm/s). The morphologies of fabricated coatings were characterized by FTIR revealing high conversion rates (e.g., from 98 to 100%) for increased exposure time as a result of the 5 or 50 mm/s values, on all combinations. Dynamic–mechanical and optical properties of UV LED-cured transparent coatings were also investigated. A negative shift of the glass transition temperature values with a decrease in exposure time, in all combinations, from about 60 °C to 30 °C, along with storage moduli lowering in the glassy plateau further favors higher exposure times for curing. The refractive indices of poly-mers were from 1.38 to 1.40, whereas the thermo-optic coefficients are showing minor changes around the value of 2.55∙10−4 K−1.

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