Hybrid Strip-Loaded Silicon Rich Nitride-Thin Film Lithium Niobate Waveguides for PIC Applications

Lately, lithium niobate on insulator (LNOI) is considered an emerging platform because of excellent intrinsic lithium niobate (LN) material properties such as wide transparency, strong electro-optic and high refractive index difference (
$\Delta n\sim 0.7$
at 1550 nm) [1]. But, the chemical stability of the LN material hinders the direct etching approach resulting in slanted waveguide sidewalls as well as current LiF diffusion or LN redeposition on the waveguide sidewalls increases the optical loss [2]. Therefore, a promising hybrid integration of the SRNLNOl platform will circumvent the existing issues of the LN material and opens up a wide prospect for developing low-loss electro-optic (EO) devices. This paper analyzes a systematic investigation by optimizing various waveguide geometrical parameters to understand the single-mode condition (SMC), zero-birefringence (ZBR), optical power distribution, and effective mode area
$(\mathrm{A}_{\text{eff}})$
of the SRN-LN hybrid waveguides.