Abstract
The mid-infrared wavelength regime 3.5 – 4.1μm, known as the astronomical L’ band is of special interest for exoplanet hunting. Mid-IR compatible photonic technologies are an enabling platform for a range of critical observational science using compact instruments on the next generation of Extremely Large Telescopes. Pupil remapping interferometry is a technique in which subapertures of the telescope pupil (2D) are reformatted into a 1D linear array. This can be done efficiently using 3D photonics. One of the most important techniques to fabricate 3D photonic devices in glass is ultrafast laser inscription. However, common silicate glasses are opaque above 2–2.2 μm and therefore not useful for the fabrication of waveguides at mid-infrared wavelengths. Here we present a study of mid-infrared transparent materials that are compatible with the ultrafast laser inscription technique. This study will inform the development of mid-infrared photonic devices for future exoplanetary discovery.
Highlights
The mid-infrared (MIR), 5-20 μm, represents a fascinating wavelength range for astronomy for a variety of reasons, for exoplanet hunting
For all the tested materials, the easiest way to generate single-mode waveguides in the L’ band was the overlap of individual modifications to create a larger structure, whether it was by generating a depressed cladding waveguide or a positive refractive index core surrounded by unmodified bulk glass
This paper reports a study of laser writing results and outlines the best strategy for successful writing of waveguides and discusses the role of the optical material properties on this process
Summary
The mid-infrared (MIR), 5-20 μm, represents a fascinating wavelength range for astronomy for a variety of reasons, for exoplanet hunting. In order to achieve good transparency at longer wavelengths exotic materials (i.e. chalcogenides, fluorides, etc) are required (featured in a special journal issue [26]) This class of glasses presents new challenges that stem from their properties such as large nonlinearities [27], brittleness and sensitivity to UV radiation or hygroscopicity [28]. Work on femtosecond laser inscription in chalcogenides started with the simplest forms of glass: arsenic selenides (As2Se3) [32] and arsenic sulphides As2S3 [21, 31, 37,38,39,40,41,42,43,44], the latter glass featuring the lowest nonlinearity by an order of magnitude among the chalcogenide glasses This makes sulphides in general more suitable when tightly focusing ultrashort laser pulses. It is important and timely to perform an ultrafast laser inscription parametric study of these glasses
Sign-in/Register to view highlights & summary 
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call