3D-Structured Polyethylene Windows for Low-Loss Transmission in Wideband Cryogenic Terahertz Systems

Fuente: arXiv
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Main Authors: Joint, François, Lapkin, Igor, Vigneron, Pierre-Baptiste, Hérault, Emilie, Meledin, Denis, Pavolotsky, Alexei, Strandberg, Magnus, Ferm, Sven Erik, Fredrixon, Mathias, Helldner, Leif, Sundin, Erik, Belitsky, Victor, Desmaris, Vincent
Format: Preprint
Published: 2025
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author Joint, François
Lapkin, Igor
Vigneron, Pierre-Baptiste
Hérault, Emilie
Meledin, Denis
Pavolotsky, Alexei
Strandberg, Magnus
Ferm, Sven Erik
Fredrixon, Mathias
Helldner, Leif
Sundin, Erik
Belitsky, Victor
Desmaris, Vincent
author_facet Joint, François
Lapkin, Igor
Vigneron, Pierre-Baptiste
Hérault, Emilie
Meledin, Denis
Pavolotsky, Alexei
Strandberg, Magnus
Ferm, Sven Erik
Fredrixon, Mathias
Helldner, Leif
Sundin, Erik
Belitsky, Victor
Desmaris, Vincent
contents We present the design, fabrication, and characterisation of a broadband vacuum window and infrared filter based on ultra-high molecular weight polyethylene (UHMWPE) for millimeter wave receivers operating across ALMA Band 6 and 7 (211-373 GHz). The window incorporates pyramidal anti-reflection (AR) structures, machined directly into the polyethylene using CNC machining, which provide impedance matching over a broad frequency range. The structured UHMWPE method was implemented in two distinct components: a vacuum window and a cryogenic infrared filter. This surface structuring approach provides mechanical robustness, cryogenic compatibility, and low insertion loss. We characterize the transmission properties using Terahertz Time-Domain Spectroscopy (THz-TDS), which demonstrates reflection below $5\%$ across the full band. Complementary heterodyne measurements confirm improved receiver noise performance. These results establish 3D structured UHMWPE as a promising platform for broadband cryogenic optics in high-sensitivity THz instrumentation.
format Preprint
id arxiv_https___arxiv_org_abs_2510_15680
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle 3D-Structured Polyethylene Windows for Low-Loss Transmission in Wideband Cryogenic Terahertz Systems
Joint, François
Lapkin, Igor
Vigneron, Pierre-Baptiste
Hérault, Emilie
Meledin, Denis
Pavolotsky, Alexei
Strandberg, Magnus
Ferm, Sven Erik
Fredrixon, Mathias
Helldner, Leif
Sundin, Erik
Belitsky, Victor
Desmaris, Vincent
Optics
Instrumentation and Detectors
We present the design, fabrication, and characterisation of a broadband vacuum window and infrared filter based on ultra-high molecular weight polyethylene (UHMWPE) for millimeter wave receivers operating across ALMA Band 6 and 7 (211-373 GHz). The window incorporates pyramidal anti-reflection (AR) structures, machined directly into the polyethylene using CNC machining, which provide impedance matching over a broad frequency range. The structured UHMWPE method was implemented in two distinct components: a vacuum window and a cryogenic infrared filter. This surface structuring approach provides mechanical robustness, cryogenic compatibility, and low insertion loss. We characterize the transmission properties using Terahertz Time-Domain Spectroscopy (THz-TDS), which demonstrates reflection below $5\%$ across the full band. Complementary heterodyne measurements confirm improved receiver noise performance. These results establish 3D structured UHMWPE as a promising platform for broadband cryogenic optics in high-sensitivity THz instrumentation.
title 3D-Structured Polyethylene Windows for Low-Loss Transmission in Wideband Cryogenic Terahertz Systems
topic Optics
Instrumentation and Detectors
url https://arxiv.org/abs/2510.15680