In this paper we report the fabrication and mid-infrared characterization (λ = 3.39 μm) of evanescent field directional couplers. These devices were fabricated using the femtosecond laser direct-writing technique in commercially available Gallium Lanthanum Sulphide (GLS) glass substrates. We demonstrate that the power splitting ratios of the devices can be controlled by adjusting the length of the interaction section between the waveguides, and consequently we demonstrate power splitting ratios of between 8% and 99% for 3.39 μm light. We anticipate that mid-IR beam integrated-optic beam combination instruments based on this technology will be key for future mid-infrared astronomical interferometry, particularly for nulling interferometry and earth-like exoplanet imaging.
|Title of host publication||Proceedings of SPIE - The International Society for Optical Engineering|
|Publication status||Published - 2014|
|Event||Optical and Infrared Interferometry IV - Montreal, United Kingdom|
Duration: 23 Jun 2014 → 27 Jun 2014
|Conference||Optical and Infrared Interferometry IV|
|Period||23/06/14 → 27/06/14|
- evanescent field couplers