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arXiv · 2510.02971

Millimeter-Wavelength Lens-Absorber-Coupled Ti/Al Kinetic Inductance Detectors

Alejandro Pascual Laguna·Victor Rollano·Aimar Najarro-Fiandra·David Rodriguez·Maria T. Magaz·Daniel Granados·Alicia Gomez
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Abstract

This work presents Ti/Al bi-layer Microwave Kinetic Inductance Detectors (MKIDs) based on lens-coupled spiral absorbers as the quasi-optical coupling mechanism for millimeter-wavelength radiation detection. From simulations, the lens-coupled absorbers provide a 70% lens aperture efficiency in both polarizations over an octave band with a spiral array absorber and over 10% relative bandwidth with a single spiral. We have fabricated and measured two devices with bare Ti/Al MKIDs: a 3x3 cm chip with 9 pixels to characterize the optical response at 85 GHz of the two variations of the absorber; and a large format demonstrator with 253 spiral-array pixels showing potential towards a large format millimeter-wavelength camera. We estimate a sensitivity of 1 $\mathrm{mK}\cdot\mathrm{Hz}^{-0.5}$ and a 95% detector yield.

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Alejandro Pascual Laguna, Victor Rollano, Aimar Najarro-Fiandra, David Rodriguez, Maria T. Magaz, Daniel Granados, Alicia Gomez. 2025-10-03. Millimeter-Wavelength Lens-Absorber-Coupled Ti/Al Kinetic Inductance Detectors. https://doi.org/10.1109/tasc.2026.3665923

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