Author(s): Zhang, L (Zhang, Lei); Fun, X (Fun, Xin); Dain, JC (Dain, Jincheng); Yang, SL (Yang, Shanglin); Zhang, GL (Zhang, Gaolu); Yang, L (Yang, Lin)

Source: OPTICS COMMUNICATIONS Volume: 479 Article Number: 126365 DOI: 10.1016/j.optcom.2020.126365 Published: JAN 15 2021

Abstract: Due to the strong birefringence, symmetrical directional couplers (DCs) are typically polarization-sensitive in the high index contrast platforms. In this letter, we demonstrate polarization-independent directional couplers utilizing orientation-engineered method on the x-cut lithium-niobate-on-insulator (LNOI) platform. We show that the polarization-dependent coupling of a DC can be greatly engineered by controlling the orientation of the waveguides in LNOI utilizing the anisotropic property of lithium niobate (LN) material. Based on the design method, a polarization-independent DC of the representative 3dB coupling ratio is realized using the ultra-sample symmetrical structure. The DC exhibits high performance in excess losses (EL < 0.1 dB) and polarization independent losses (PDL < 0.08 dB) over a 100-nm wavelength range.

Accession Number: WOS:000585299600028

ISSN: 0030-4018

eISSN: 1873-0310

Full Text: https://www.sciencedirect.com/science/article/pii/S0030401820307823?via%3Dihub