Validity of analytical Microwave Kinetic Inductance Detector responsivity expressions

Elmore Vaal

Published Jan 1, 2016• 0 citations

Abstract

Astrophysical photons with a sub-millimetre wavelength are of great value to research star and galaxy formation. Superconductors have a small energy gap with which these sub-millimetre photons can be measured. Superconductors can absorb photons so that quasiparticles are created, which will in turn change the complex conductivity: incoming photons change the electrical response of the superconductor. This principle can be used to realise a detector. This is done with the Microwave Kinetic Inductance Detectors (MKIDs) that consist of a superconducting film embedded in a resonant circuit, so that photons falling in will change the resonant frequency. This can be measured with a readout signal. To enhance the sensitivity of the MKID, we want to increase the responsivity of an MKID as much as possible.A previous study has proposed a figure of merit regarding the material properties of a superconductor to achieve a high responsivity. However, the readout frequency used is not included in this figure. The goal of this work is to extend the figure of merit so that the readout frequency of the MKID can be optimised for a higher responsivity.

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