Astrophotonics (AP)
K-band integrated optics beam combiners for CHARA
K-band integrated optics beam combiners for CHARA fabricated by ultrafast laser inscription
Fraser A. Pike; Tarun K. Sharma; Aurélien Benoît; David G. MacLachlan; Aline N. Dinkelaker; Abani S. Nayak; Kalaga Madhav; Martin M. Roth; Lucas Labadie; Ettore Pedretti; Theo A.
We report the ultrafast laser inscription (ULI) and characterization of 3 dB directional achromatic couplers for K-band between 2 and 2.4 μm. The couplers were fabricated in commercial Infrasil glass using 1030 nm femtosecond laser pulses. Straight waveguides inscribed using optimal fabrication parameters exhibit an average propagation loss of ∼1.21 dB over full range of K-band with a single-mode behavior for a length of 17 mm. Directional couplers with different interaction lengths and waveguide widths were fabricated and characterized. We demonstrate that 3 dB achromatic directional couplers for K-band can be fabricated using ULI. These results show that ULI can fabricate highquality couplers for future applications in astronomical interferometry. Our eventual aim is to develop a two-telescope K-band integrated optical beam combiner to replace JouFLU at CHARA.
Journal Article