AC bias characterization of low noise bolometers for SAFARI using an Open-Loop Frequency Domain SQUID-based multiplexer operating between 1 and 5 MHz

TL;DR

This paper presents an AC bias characterization method for low noise TES bolometers using a frequency domain multiplexer operating between 1 and 5 MHz, optimized for space-based infrared spectroscopy.

Contribution

It introduces a simple open-loop FDM system for single pixel TES characterization in the 1-5 MHz range, with detailed experimental setup and performance comparison under AC and DC bias.

Findings

Achieved low power loading (< 1 fW) and low NEP (~10^{-19} W/Hz^{1/2}) in TES bolometers.

Demonstrated comparable performance of TES under AC and DC bias.

Developed a prototype system suitable for space-based infrared spectrometry.

Abstract

SRON is developing the Frequency Domain Multiplexing (FDM) readout and the ultra low NEP TES bolometers array for the infrared spectrometer SAFARI on board of the Japanese space mission SPICA. The FDM prototype of the instrument requires critical and complex optimizations. For single pixel characterization under AC bias we are developing a simple FDM system working in the frequency range from 1 to 5 MHz, based on the open loop read-out of a linearized two-stage SQUID amplifier and high Q lithographic LC resonators. We describe the details of the experimental set-up required to achieve low power loading (< 1 fW) and low noise (NEP $\sim 10^{-19} W/Hz^{1/2}$) in the TES bolometers. We conclude the paper by comparing the performance of a $4 \cdot 10^{-19} W/Hz^{1/2}$ TES bolometer measured under DC and AC bias.