The Simulation and Design of an On-Chip Superconducting Millimetre Filter-Bank Spectrometer

TL;DR

This paper introduces a superconducting on-chip filter-bank spectrometer design that is scalable, fabrication error tolerant, and suitable for millimetre wavelength imaging, with promising efficiency and spectral resolution.

Contribution

The authors present a lithographed superconducting filter design with high fabrication error tolerance and integrated with LEKID detectors for scalable millimetre-wave spectroscopy.

Findings

Filter quality factor varies less than 11% with fabrication errors

Full filter-bank efficiency forecasted at 60%

Spectral pass band defined by a $b1/2$ microstrip resonator

Abstract

Superconducting on-chip filter-banks provide a scalable, space saving solution to create imaging spectrometers at millimetre and sub-millimetre wavelengths. We present an easy to realise, lithographed superconducting filter design with a high tolerance to fabrication error. Using a capacitively coupled $\lambda/2$ microstrip resonator to define a narrow ($\lambda/\Delta\lambda = 300$) spectral pass band, the filtered output of a given spectrometer channel directly connects to a Lumped Element Kinetic Inductance Detector (LEKID). We show the tolerance analysis of our design, demonstrating $<11\%$ change in filter quality factor to any one realistic fabrication errors and a full filter-bank efficiency forecast to be 60\% after accounting for fabrication errors and dielectric loss tangent.