A mid-infrared broadband achromatic astronomical beam combiner for nulling interferometry

TL;DR

This paper presents a theoretical design for a broadband, achromatic, polarization-insensitive integrated optic beam combiner operating in the mid-infrared, enabling deep nulls for exoplanet detection.

Contribution

It introduces a novel three-waveguide design technique for broadband, achromatic, and lossless beam combining in the mid-infrared, expanding capabilities for astronomical interferometry.

Findings

Design achieves fully achromatic, broadband operation

Potential for very deep broadband nulls in exoplanet searching

Operates in mid-infrared wavelength region

Abstract

Integrated optic beam combiners offer many advantages over conventional bulk optic implementations for astronomical imaging. To date, integrated optic beam combiners have only been demonstrated at operating wavelengths below 4 microns. Operation in mid-infrared wavelength region, however, is highly desirable. In this paper, a theoretical design technique based on three coupled waveguides is developed to achieve fully achromatic, broadband, polarization-insensitive, lossless beam combining. This design may make it possible to achieve the very deep broadband nulls needed for exoplanet searching.