A Titanium Nitride Absorber for Controlling Optical Crosstalk in Horn-Coupled Aluminum LEKID Arrays for Millimeter Wavelengths

TL;DR

This paper presents a titanium nitride mesh absorber designed to significantly reduce optical crosstalk in millimeter-wavelength LEKID arrays, demonstrating a 66% reduction in measured crosstalk and improving detector performance.

Contribution

The paper introduces a novel TiN mesh absorber integrated into LEKID arrays, effectively reducing optical crosstalk and enhancing array performance for millimeter-wavelength applications.

Findings

Optical crosstalk reduced by 66% with TiN absorber

TiN mesh is effective for controlling crosstalk in LEKID arrays

Demonstrated viability for future kilo-pixel detector arrays

Abstract

We discuss the design and measured performance of a titanium nitride (TiN) mesh absorber we are developing for controlling optical crosstalk in horn-coupled lumped-element kinetic inductance detector arrays for millimeter-wavelengths. This absorber was added to the fused silica anti-reflection coating attached to previously-characterized, 20-element prototype arrays of LEKIDs fabricated from thin-film aluminum on silicon substrates. To test the TiN crosstalk absorber, we compared the measured response and noise properties of LEKID arrays with and without the TiN mesh. For this test, the LEKIDs were illuminated with an adjustable, incoherent electronic millimeter-wave source. Our measurements show that the optical crosstalk in the LEKID array with the TiN absorber is reduced by 66\% on average, so the approach is effective and a viable candidate for future kilo-pixel arrays.