Near-Infrared InGaAs Detectors for Background-limited Imaging and Photometry

TL;DR

This paper demonstrates the development and testing of InGaAs near-infrared detectors capable of background-limited performance for ground-based astronomical imaging, highlighting their potential for cost-effective, large-scale, multi-band astronomical instruments.

Contribution

The paper presents a new camera system using InGaAs detectors with minimized noise, achieving stable photometric performance suitable for exoplanet detection and other time-domain astronomy applications.

Findings

Dark current of 163 e- s^-1 pix^-1

Read noise of 87 e- (up-the-ramp)

Photometric stability of 230 ppm hr^-1/2

Abstract

Originally designed for night-vision equipment, InGaAs detectors are beginning to achieve background-limited performance in broadband imaging from the ground. The lower cost of these detectors can enable multi-band instruments, arrays of small telescopes, and large focal planes that would be uneconomical with high-performance HgCdTe detectors. We developed a camera to operate the FLIR AP1121 sensor using deep thermoelectric cooling and up-the-ramp sampling to minimize noise. We measured a dark current of 163$~e$- s$^{-1}$ pix$^{-1}$, a read noise of 87$~e$- up-the-ramp, and a well depth of 80k$~e$-. Laboratory photometric testing achieved a stability of 230 ppm hr$^{-1/2}$, which would be required for detecting exoplanet transits. InGaAs detectors are also applicable to other branches of near-infrared time-domain astronomy, ranging from brown dwarf weather to gravitational wave follow-up.