Arrayed Waveguide Gratings on Integrated Thin-Film Lithium Tantalate

Abstract

Arrayed Waveguide Gratings (AWGs) are ubiquitous and efficient photonic devices used to split and combine different wavelengths of light. They have been widely used as (de)-multiplexer for wavelength division multiplexed optical communication systems, and as a building block for optical signal processing, computing, spectroscopic and sensing applications. Over the past decades, AWGs have been demonstrated in various photonic integrated platforms across silica, silicon, silicon nitride, polymer, and indium phosphide [1]. Recently, there has been growing interest in integrating AWGs in ferroelectric material platform, as the platform simultaneously provides efficient electro-optic modulation capability and thus holds the promise for fully integrated WDM transmitters. Several demonstrations on the thin-film lithium niobate (TFLN) platform have been reported [2], [3], with X-cut TFLN being particularly notable for its high Pockels coefficient. However, the large anisotropy of lithium niobate complicates the design and degrades the performance of the AWGs. To address this limitation, we use thin-film lithium tantalate (TFLT) [4], a material with similar Pockels coefficient as TFLN but significantly reduced optical anisotropy (more than 10-times reduction in birefringence), as an alternative viable platform.