Mid-infrared astrophotonics: study of ultrafast laser induced index change in compatible materials

Abstract

The mid-infrared wavelength regime 3:5 􀀀 4:1 m, known as the astronomical L’
\nband is of special interest for exoplanet hunting. Mid-IR compatible photonic technologies are
\nan enabling platform for a range of critical observational science using compact instruments
\non the next generation of Extremely Large Telescopes. Pupil remapping interferometry is a
\ntechnique in which subapertures of the telescope pupil (2D) are reformatted into a 1D linear
\narray. This can be done efficiently using 3D photonics. One of the most important techniques to
\nfabricate 3D photonic devices in glass is ultrafast laser inscription. However, common silicate
\nglasses are opaque above 2-2.2 m and therefore not useful for the fabrication of waveguides at
\nmid-infrared wavelengths. Here we present a study of mid-infrared transparent materials that are
\ncompatible with the ultrafast laser inscription technique. This study will inform the development
\nof mid-infrared photonic devices for future exoplanetary discovery.