Authors:	Xiangyu Xue, E. Lievens, Brecht Berteloot, Yu-Tung Hsiao, Lukas Van Iseghem, Gilles Freddy Feutmba, Wim Bogaerts, Kristiaan Neyts, Jeroen Beeckman
Title:	Vertical coupling between waveguides and optical fibers utilizing polarization gratings
Format:	International Journal
Publication date:	3/2024
Journal/Conference/Book:	IEEE Photonics Technology Letters
Volume(Issue):	36(5) p. 309-312
DOI:	10.1109/lpt.2024.3352278
Citations:	4 (Dimensions.ai - last update: 19/1/2025) Look up on Google Scholar
Download:	(1.3MB)

Abstract

We present how a conventional Si waveguide grating coupler can be integrated with a polymerizable liquid crystal polarization grating to provide vertical coupling between optical fibers and planar waveguides. The implementation involves the deposition of a liquid crystal polymer film onto the surface of the planarized photonic chip. To achieve optimal performance, both the period and thickness of the thin film grating are optimized through a two-dimensional finite element simulation. The simulation results indicate that the output beam can be entirely redirected towards the vertical direction. We demonstrate a fabricated device and experimental validation of the proposed device in a laboratory setting. Through the verification, we affirm the feasibility of the proposed concept.