# Broadband on-chip single-photon spectrometer

## TL;DR

This paper introduces a compact, broadband on-chip single-photon spectrometer capable of high-resolution spectral detection across visible and infrared wavelengths, enabling advanced applications in quantum communication and spectroscopy.

## Contribution

The first integrated chip-scale single-photon spectrometer covering 600nm to 2000nm with high spectral resolution and scalability, combining an on-chip dispersive grating with superconducting nanowire detectors.

## Key findings

- Achieved broadband detection from 600nm to 2000nm
- Integrated high-resolution dispersive grating on-chip
- Demonstrated scalable, robust device with over 200 channels

## Abstract

Single-photon counters are single-pixel binary devices that click upon the absorption of a photon but obscure its spectral information, whereas resolving the colour of detected photons has been in critical demand for frontier astronomical observation, spectroscopic imaging and wavelength division multiplexed quantum communications. Current implementations of single-photon spectrometers either consist of bulky wavelength-scanning components or have limited detection channels, preventing parallel detection of broadband single photons with high spectral resolutions. Here, we present the first broadband chip-scale single-photon spectrometer covering both visible and infrared wavebands spanning from 600nm to 2000nm. The spectrometer integrates an on-chip dispersive echelle grating with a single-element propagating superconducting nanowire detector of ultraslow-velocity for mapping the dispersed photons with high spatial resolutions. The demonstrated on-chip single-photon spectrometer features small device footprint, high robustness with no moving parts and meanwhile offers more than 200 equivalent wavelength detection channels with further scalability.