Optical characterization of ultra-short Bragg grating on lithium niobate ridge waveguide

Clément Guyot (1) , Gwenn Ulliac (1) , Jean Dahdah (2) , Wentao Qiu (1) , Maria-Pilar Bernal (1) , Fadi Issam Baida (1) , Nadège Courjal (1)

1 FEMTO-ST - Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174)
2 Kapteos SAS

In this Letter, we report a technique to etch giant aspect ratio nanostructures in lithium niobate. An 8 μm long Bragg grating on a Ti:LiNbO3 ridge waveguide was fabricated by combining optical-grade dicing and focused ion beam milling. The reflectivity was evaluated using an optical coherence tomography system: it is measured to be 53% for the TM wave and 47% for the TE wave. We study by 2D-FDTD the modeled behavior of the electromagnetic field when an angle exists between two consecutive sidewalls of the grating in order to understand the difference between ideal Bragg grating and experimental samples. These simulations allow us to optimize the parameters in order to increase the reflection of the grating up to 80%.

Domaines: Optique / photonique; Optique [physics.optics]

Clément Guyot, Gwenn Ulliac, Jean Dahdah, Wentao Qiu, Maria-Pilar Bernal, et al.. Optical characterization of ultra-short Bragg grating on lithium niobate ridge waveguide. Optics Letters, 2014, 39, pp.371 - 374. ⟨10.1364/OL.39.000371⟩. ⟨hal-00942573⟩