High-performance arrayed waveguide gratings on x-cut thin-film lithium niobate for 50-GHz-grid DWDM

Designing and fabricating narrow-channel-spacing arrayed waveguide gratings (AWGs) on anisotropic materials like x-cut thin-film lithium niobate (TFLN) is highly challenging. Here, we present two models and their design approaches for AWGs with a channel spacing of 0.4 nm (50 GHz at C-band), for dense wavelength division multiplexing applications on TFLN. The designed 9 × 9 AWGs can be configured for an 8-channel add-drop filter with automatically aligned wavelengths. The fabricated devices present insertion losses as low as 3.2 dB and crosstalk of >20 dB. These high-performance devices, combined with electro-optical modulators on the same platform, hold significant potential for applications in multiwavelength digital and analog optical communications and signal processing.