Development of Silicon Micromachined Waveguide Filter-Banks for On-Chip Spectrometers

TL;DR

This paper reports the fabrication of a silicon micromachined waveguide filter-bank for on-chip spectrometers, achieving high optical efficiency and spectral resolution, advancing millimeter-wave spectroscopy for astronomy applications.

Contribution

It introduces a novel deep reactive ion etching fabrication process for high-density, high-efficiency silicon waveguide filter-banks compatible with multiplexed detector arrays.

Findings

Measured resolving power of 263 at room temperature

Loss quality factor of 1116 indicating low loss

Excellent match between test waveguide and simulations

Abstract

Development of high-speed, spatial-mapping spectrometers in the millimeter and far-infrared frequencies would enable entirely new research avenues in astronomy and cosmology. An "on-chip" spectrometer is one such technology that could enable Line Intensity Mapping. Recent work has shown the promise of high-speed imaging; however, a limiting factor is that many of these devices suffer from low optical efficiency. Here we present the fabrication of a metalized, Si waveguide filter-bank fabricated using deep reactive ion etching for use in millimeter spectroscopy. Our design simultaneously provides high-density pixel packing, high optical efficiency, high spectral resolution, and is readily compatible with simple and multiplexable MKID arrays. Gold plated test waveguide and filter show excellent match to simulations with a measured resolving power of 263 and a loss quality factor of 1116 at room temperature. The results show promise for extending the measurements to larger, multi-wavelength designs.