Ultrafast laser inscription of integrated optics two-telescope beam combiners for K-band interferometry at the CHARA array

Jacopo Siliprandi; David G. MacLachlan; Calum A. Ross; Tarun K. Sharma; Lucas Labadie; Kalaga Madhav; Abani S. Nayak; Aline N. Dinkelaker; Martin M. Roth; Ettore Pedretti; Theo A. ten Brummelaar; Nicholas J. Scott; Vincent Coudé du Foresto; Robert R. Thomson; Aurélien Benoît

doi:10.1117/12.2629899

26 August 2022 Ultrafast laser inscription of integrated optics two-telescope beam combiners for K-band interferometry at the CHARA array

Jacopo Siliprandi, David G. MacLachlan, Calum A. Ross, Tarun K. Sharma, Lucas Labadie, Kalaga Madhav, Abani S. Nayak, Aline N. Dinkelaker, Martin M. Roth, Ettore Pedretti, Theo A. ten Brummelaar, Nicholas J. Scott, Vincent Coudé du Foresto, Robert R. Thomson, Aurélien Benoît

Author Affiliations +

Proceedings Volume 12183, Optical and Infrared Interferometry and Imaging VIII; 1218314 (2022) https://doi.org/10.1117/12.2629899
Event: SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

Abstract

We report the ultrafast laser inscription (ULI) of a 2-telescope integrated optic (IO) beam combiner for K-band interferometry in commercial Infrasil glass. The ULI setup used for this work is based on a 1030 nm femtosecond laser which is paired with a spatial-light-modulator (SLM). The SLM controls the numerical aperture of the focused beam used to write waveguides in the substrate. The optimum ULI parameters were found to inscribe straight single-mode waveguides exhibiting an insertion loss of 1.1 ± 0.1 dB for a 17 mm long chip over the entire K-band. To develop optimal directional couplers, we focused our efforts on investigating the effect of varying the core-to-core separation and the effect of detuning the waveguide parameters in the coupler. By doing so, we have identified fabrication parameters that are suitable for the fabrication of a beam combiner integrating an achromatic 3 dB directional coupler and two photometric taps with a splitting ratio of 80:20. These results demonstrate the capability of the ULI fabrication technique to inscribe efficient achromatic directional couplers in the K-band range. A final fabrication step will involve simple assembly of the beam combiner with input/output fibers in preparation for on-sky testing at the CHARA array planned for July 2022.

Conference Presentation

Citation Download Citation

Jacopo Siliprandi, David G. MacLachlan, Calum A. Ross, Tarun K. Sharma, Lucas Labadie, Kalaga Madhav, Abani S. Nayak, Aline N. Dinkelaker, Martin M. Roth, Ettore Pedretti, Theo A. ten Brummelaar, Nicholas J. Scott, Vincent Coudé du Foresto, Robert R. Thomson, and Aurélien Benoît "Ultrafast laser inscription of integrated optics two-telescope beam combiners for K-band interferometry at the CHARA array", Proc. SPIE 12183, Optical and Infrared Interferometry and Imaging VIII, 1218314 (26 August 2022); https://doi.org/10.1117/12.2629899

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available