Optical Response of Lumped-Element Kinetic-Inductance Detector Arrays

TL;DR

This paper analyzes the optical response of lumped-element kinetic-inductance detector arrays, combining simulations and measurements to validate models and explore efficiency improvements for millimeter and terahertz applications.

Contribution

It provides a combined simulation and experimental analysis of the optical response of KID arrays, validating models and suggesting optimization strategies.

Findings

Simulations predict a 20% difference in absorption efficiencies.

Fourier-transform spectroscopy validates the simulation results.

Potential methods for increasing absorption efficiency are discussed.

Abstract

We present an analysis of the optical response of lumped-element kinetic-inductance detector arrays, based on the NIKA2 1mm array. This array has a dual-polarization sensitive Hilbert inductor for directly absorbing incident photons. We present the optical response calculated from a transmission line model, simulated with HFSS and measured using a Fourier transform spectrometer. We have estimated the energy absorbed by individual component of a pixel, such as the inductor. The difference between the absorption efficiencies is expected to be 20% from the simulations. The Fourier-transform spectroscopy measurement, performed on the actual NIKA2 arrays, validates our simulations. We discuss several possible ways to increase the absorption efficiency. This analysis can be used for optimization of the focal plane layout and can be extended to other kinetic inductance detector array designs in millimeter, sub-millimeter and terahertz frequency bands.