Extending the optical absorption in a lumped element meander structure to far-infrared wavelengths

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Hauptverfasser: Pandey, Shekhar Chandra, Sharma, Shilpam, Singh, Anudeep, Pandey, Utkarsh, Prabhu, S. S., Biswas, Bhaskar, Chandran, Sona, Chattopadhyay, M. K.
Format: Preprint
Veröffentlicht: 2025
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author Pandey, Shekhar Chandra
Sharma, Shilpam
Singh, Anudeep
Pandey, Utkarsh
Prabhu, S. S.
Biswas, Bhaskar
Chandran, Sona
Chattopadhyay, M. K.
author_facet Pandey, Shekhar Chandra
Sharma, Shilpam
Singh, Anudeep
Pandey, Utkarsh
Prabhu, S. S.
Biswas, Bhaskar
Chandran, Sona
Chattopadhyay, M. K.
contents Superconducting radiation detectors typically exhibit detection and single photon sensitivity limited to the mid infrared wavelength range. Extending their detection capabilities into the far infrared range (>10 um) requires careful selection of substrate materials and detector geometries. The overall detection efficiency is linked to absorption and coupling efficiencies. In this study, the resonator geometry and absorption efficiency were estimated using electromagnetic simulations in CST Microwave Studio for a lumped-element meander structure. Simulations were performed for the 12 to 50 um wavelength range, corresponding to the Infrared Free Electron Laser (IR FEL) at RRCAT, Indore. Absorption in the meander inductor was influenced by the substrate material, thickness, and impedance matching between the detector and incident photon medium. The results indicate that SiO2 and diamond substrates are suitable for developing lumped-element kinetic inductance detectors (LEKID) in this range. Optimized meander geometries on diamond substrates demonstrated absorption efficiencies of up to 95% for narrow bandwidths and over 50% for wide bandwidths. A 30-pixel LEKID structure was fabricated using electron beam lithography on a 500 um SiO2 coated Si substrate, with a 20 nm thick Ti40V60 alloy resonator. Experimental absorption efficiency was determined through transmission and reflection measurements. Results show that in the 14 to 26 um IR-FEL range, the LEKID achieved up to 75% absorption efficiency. These studies demonstrate that the LEKID structure is ideal for detecting far infrared wavelengths above 10 um, with high absorption efficiency.
format Preprint
id arxiv_https___arxiv_org_abs_2509_21951
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Extending the optical absorption in a lumped element meander structure to far-infrared wavelengths
Pandey, Shekhar Chandra
Sharma, Shilpam
Singh, Anudeep
Pandey, Utkarsh
Prabhu, S. S.
Biswas, Bhaskar
Chandran, Sona
Chattopadhyay, M. K.
Superconductivity
Superconducting radiation detectors typically exhibit detection and single photon sensitivity limited to the mid infrared wavelength range. Extending their detection capabilities into the far infrared range (>10 um) requires careful selection of substrate materials and detector geometries. The overall detection efficiency is linked to absorption and coupling efficiencies. In this study, the resonator geometry and absorption efficiency were estimated using electromagnetic simulations in CST Microwave Studio for a lumped-element meander structure. Simulations were performed for the 12 to 50 um wavelength range, corresponding to the Infrared Free Electron Laser (IR FEL) at RRCAT, Indore. Absorption in the meander inductor was influenced by the substrate material, thickness, and impedance matching between the detector and incident photon medium. The results indicate that SiO2 and diamond substrates are suitable for developing lumped-element kinetic inductance detectors (LEKID) in this range. Optimized meander geometries on diamond substrates demonstrated absorption efficiencies of up to 95% for narrow bandwidths and over 50% for wide bandwidths. A 30-pixel LEKID structure was fabricated using electron beam lithography on a 500 um SiO2 coated Si substrate, with a 20 nm thick Ti40V60 alloy resonator. Experimental absorption efficiency was determined through transmission and reflection measurements. Results show that in the 14 to 26 um IR-FEL range, the LEKID achieved up to 75% absorption efficiency. These studies demonstrate that the LEKID structure is ideal for detecting far infrared wavelengths above 10 um, with high absorption efficiency.
title Extending the optical absorption in a lumped element meander structure to far-infrared wavelengths
topic Superconductivity
url https://arxiv.org/abs/2509.21951