Design of Green Light Sources Using Nonlinear Photonics and On-Chip Pump Lasers

A fully-functional photonic integrated circuit (PIC) platform with supporting active and passive components in the green part of the visible spectral regime is of significant research interest for next-generation optical systems. Here we design highly-integrated ∼3.5 mm long PICs at green wavelengths, which consist of on-chip GaAs-based near-infrared pump lasers, SiN-LiNbO
₃
hybrid waveguides and ring resonators for nonlinear frequency conversion. The waveguides in the PICs are designed to eliminate etching of LiNbO
₃
, reducing fabrication challenges. Efficient wavelength of 1062 nm pump to 531 nm coherent light is achieved by employing modal phase matching. Unlike a quasi-phase matching technique, modal phase matching enables poling-free operation and further eases device fabrication with comparable performance in terms of second harmonic generation efficiency. The effective nonlinear mode-overlap factor between 1062-nm-TE
₀₀
and 531-nm-TE
₀₁
modes in the hybrid waveguide is calculated to be 26%. For robust on-chip light coupling between pump laser and waveguide, a calculated maximum coupling efficiency of −2.3 dB is achieved. The theoretical work presented is an initial step towards demonstrating complex non-telecom PICs which could offer a comprehensive range of photonic functionalities.