Spatial and frequency dependencies of local photoresponse of HTS strip-line resonator in regime of two-tone microwave intermodulation excitation

TL;DR

This paper introduces a phenomenological method using Laser Scanning Microscopy to analyze the spatial and frequency-dependent nonlinear microwave responses of superconducting resonators, distinguishing resistive and inductive contributions at IMD frequencies.

Contribution

It presents a novel approach to spatially resolve and analyze the nonlinear microwave photoresponse of superconducting resonators at intermodulation frequencies.

Findings

Successfully separated resistive and inductive IMD contributions.

Demonstrated spatially-resolved analysis of nonlinear sources.

Applied the method to two-tone microwave excitation data.

Abstract

A new phenomenological approach to spatially-resolved research of nonlinear (NL) microwave properties of operating thin-film superconducting resonators is proposed. The approach is based on frequency and spatial singularity of Laser Scanning Microscopy (LSM) images that can be extracted from a set of 2-D patterns representing x-y distribution of the LSM photoresponse, PR(x, y), at fixed third-order intermodulation (IMD) frequencies 2f1-f2 and 2f2-f1 as a result of two-tone resonator microwave excitation at equidistant frequencies f1 and f2 relative to the fundamental resonance, f0. It was shown by us earlier that the total LSM PR(x, y) originates from two independent (resistive, PRR(x, y), and inductive, PRX(x, y)) contributions which can be extracted directly from the LSM images acquired at f1 and f2 by using a method of spatially-resolved complex impedance partition [1]. Here, we show that practically the same manipulation of LSM images at 2f1-f2 and 2f2-f1 can be used to present NL components of IMD LSM PR(x, y) in terms of its independent spatial variations of (i) inductive IMD_IND(x, y) and (ii) resistive IMD_RES(x, y) contributions reflecting the origin of the local sources of microwave NL. [1] A.P. Zhuravel, S.M. Anlage, and A.V. Ustinov, Appl. Phys. Lett., vol. 88, p. 212503, 2006.