Anisotropy-free arrayed waveguide gratings on X-cut thin film lithium niobate platform of in-plane anisotropy
Junjie Yi, Changjian Guo, Ziliang Ruan, Gengxin Chen, Haiqiang Wei, Liwang Lu, Shengqi Gong, Xiaofu Pan, Xiaowan Shen, Xiaowei Guan, Daoxin Dai, Kangping Zhong, Liu Liu
Abstract
Arrayed waveguide grating is a versatile and scalable integrated light dispersion device, which has been widely adopted in various applications, including, optical communications and optical sensing. Recently, thin-film lithium niobate emerges as a promising photonic integration platform, due to its ability of shrinking largely the size of typical lithium niobate based optical devices. This would also enable multifunctional photonic integrated chips on a single lithium niobate substrate. However, due to the intrinsic anisotropy of the material, to build an arrayed waveguide grating on X-cut thin-film lithium niobate has never been successful. Here, a universal strategy to design anisotropy-free dispersive components on a uniaxial in-plane anisotropic photonic integration platform is introduced for the first time. This leads to the first implementation of arrayed waveguide gratings on X-cut thin-film lithium niobate with various configurations and high-performances. The best insertion loss of 2.4 dB and crosstalk of -24.1 dB is obtained for the fabricated arrayed waveguide grating devices. Applications of such arrayed waveguide gratings as a wavelength router and in a wavelength-division multiplexed optical transmission system are also demonstrated.