A Frequency Selective Surface based focal plane receiver for the OLIMPO balloon-borne telescope

TL;DR

This paper introduces a novel focal plane array using a Frequency Selective Surface integrated with Cold-Electron Bolometers for 350 GHz detection, optimized for balloon-borne telescope applications.

Contribution

It presents the design, simulation, fabrication, and testing of a FSS-based CEB detector array for improved sub-mm astronomical observations.

Findings

Achieved background noise limited operation for 20-80 pW incident power

Demonstrated optical response matching CEB model predictions

Estimated NEP suitable for sensitive astronomical measurements

Abstract

We describe here a focal plane array of Cold-Electron Bolometer (CEB) detectors integrated in a Frequency Selective Surface (FSS) for the 350 GHz detection band of the OLIMPO balloon-borne telescope. In our architecture, the two terminal CEB has been integrated in the periodic unit cell of the FSS structure and is impedance matched to the embedding impedance seen by it and provides a resonant interaction with the incident sub-mm radiation. The detector array has been designed to operate in background noise limited condition for incident powers of 20 pW to 80 pW, making it possible to use the same pixel in both photometric and spectrometric configurations. We present high frequency and dc simulations of our system, together with fabrication details. The frequency response of the FSS array, optical response measurements with hot/cold load in front of optical window and with variable temperature black body source inside cryostat are presented. A comparison of the optical response to the CEB model and estimations of Noise Equivalent power (NEP) is also presented.