A four-pole power-combiner design for far-infrared and submillimeter spectroscopy

TL;DR

This paper presents a novel four-pole power combiner design for a high-efficiency spectrometer operating in the far-infrared and submillimeter range, enhancing spaceflight instrumentation capabilities.

Contribution

It introduces a new four-stigmatic-point optical design for a micro-Spec spectrometer, expanding the design space by removing traditional focal-plane constraints.

Findings

Identified a new four-stigmatic-point optical configuration

Optimized geometrical configurations for specific spectral and size requirements

Demonstrated potential improvements in spectrometer performance

Abstract

The far-infrared and submillimeter portions of the electromagnetic spectrum provide a unique view of the astrophysical processes present in the early universe. Micro-Spec ($\mu$-Spec), a high-efficiency direct-detection spectrometer concept working in the 450-1000-$\mu$m wavelength range, will enable a wide range of spaceflight missions that would otherwise be challenging due to the large size of current instruments and the required spectral resolution and sensitivity. This paper focuses on the $\mu$-Spec two-dimensional multimode region, where the light of different wavelengths diffracts and converges onto a set of detectors. A two-step optimization process is used to generate geometrical configurations given specific requirements on spectrometer size, operating spectral range, and performance. The canonically employed focal-plane constraints for the power combiner were removed to probe the design space in its entirety. A new four-stigmatic-point optical design solution is identified and explored for use in far-infrared and submillimeter spectroscopy.