Author(s)

Chen Zhang, Christi K. Madsen

Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, USA.

We present both design and experimental results for an As₂S₃ grating coupler on a thin film LiNbO₃ substrate. A basic grating coupler structure is designed with coupling efficiency of 53% to a single mode fiber. A maximum simulated coupling efficiency of 78.8% is achieved, assuming a polymer bonding process. The basic structure was fabricated, and the coupling efficiency was measured to be at least 23.4% at 1540 nm. Some of the loss may be attributable to non-grating sources, such as waveguide tapers and testing fiber tails. A grating cavity was then measured using the grating couplers. The cavity waveguide propagation loss was 2.0 dB/cm. For a 400 nm thick As₂S₃ on 500 nm thin film LiNbO₃ on insulator, the confinement factor in the LiNbO₃ crystal is 82.3% when the As₂S₃ waveguide width is 400 nm, showing that As₂S₃-on-thin film LiNbO₃ is an excellent candidate for thin film electro-optic applications.

Thin Film Lithium Niobate, Arsenic Trisulfide Waveguide, Grating Coupler, Grating Cavity

Zhang, C. and Madsen, C. (2018) Demonstration of an As₂S₃ Grating Coupler on Thin Film LiNbO₃. Optics and Photonics Journal, 8, 111-121. doi: 10.4236/opj.2018.84011.