Nonlinear Self-Calibrated Spectrometer with Single GeSe-InSe Heterojunction Device

TL;DR

This paper presents a compact, nonlinear GeSe-InSe heterojunction spectrometer that employs neural networks to accurately recover spectral information from nonlinear device responses, enabling high-resolution spectroscopy in a small footprint.

Contribution

It introduces a neural network-based calibration method for a nonlinear, single-photodetector spectrometer using layered 2D materials, achieving high accuracy and resolving metamerism.

Findings

Achieved mean spectral reconstruction error of 0.0002

Operates effectively over 400-1100 nm range

Device footprint of approximately 25x25 micrometers

Abstract

Optical spectroscopy the measurement of electromagnetic spectra is fundamental to various scientific domains and serves as the building block of numerous technologies. Computational spectrometry is an emerging field that employs an array of photodetectors with different spectral responses or a single photodetector device with tunable spectral response, in conjunction with numerical algorithms, for spectroscopic measurements. Compact single photodetectors made from layered materials are particularly attractive, since they eliminate the need for bulky mechanical and optical components used in traditional spectrometers and can easily be engineered as heterostructures to optimize device performance. However, compact tunable photodetectors are typically nonlinear devices and this adds complexity to extracting optical spectra from the device response. Here, we report on the training of an artificial neural network (ANN) to recover the full nonlinear spectral photoresponse of a nonlinear problem of high dimensionality of a single GeSe-InSe p-n heterojunction device. We demonstrate the functionality of a calibrated spectrometer in the spectral range of 400-1100 nm, with a small device footprint of ~25X25 micrometers, and we achieve a mean reconstruction error of 0.0002 for the power-spectrum at a spectral resolution of 0.35 nm. Using our device, we demonstrate a solution to metamerism, an apparent matching of colors with different power spectral distributions, which is a fundamental problem in optical imaging.