Power Handling and Responsivity of Submicron Wide Superconducting Coplanar Waveguide Resonators

TL;DR

This study investigates how reducing the width of superconducting coplanar waveguide resonators to submicron scales affects their power handling and responsivity, aiming to enhance the sensitivity of microwave detectors for space-based terahertz astronomy.

Contribution

It demonstrates that responsivity, noise, and power handling characteristics persist down to 300 nm widths, supporting the development of narrower KIDs for improved sensitivity.

Findings

Responsivity remains effective at 300 nm width

Power handling capabilities are maintained at submicron scales

Encourages development of narrow Al KIDs for better sensitivity

Abstract

The sensitivity of microwave kinetic inductance detectors (MKIDs) based on coplanar waveguides (CPWs) needs to be improved by at least an order of magnitude to satisfy the requirements for space-based terahertz astronomy. Our aim is to investigate if this can be achieved by reducing the width of the CPW to much below what has typically been made using optical lithography (> 1 {\mu}m). CPW resonators with a central line width as narrow as 300 nm were made in NbTiN using electron beam lithography and reactive ion etching. In a systematic study of quarter-wave CPW resonators with varying widths it is shown that the behavior of responsivity, noise and power handling as a function of width continues down to 300 nm. This encourages the development of narrow KIDs using Al in order to improve their sensitivity.