High-Efficiency Second-Harmonic and Sum-Frequency Generation in a Silicon Nitride Microring Integrated with Few-Layer GaSe

Silicon nitride (SiN) photonics platform has attributes of ultra-low linear and nonlinear propagation losses CMOS-compatible fabrication process, promising large-scale multifunctional photonic circuits. However, the centrosymmetric nature SiN inhibits second-order optical responses in its platform, which is desirable for developing efficient active devices. Here, we demonstrate high-efficiency processes by integrating a few-layer GaSe flake on microring resonator. With pump microwatts continuous-wave lasers, second-harmonic generation sum-frequency with conversion efficiencies 849%/W 123%/W, respectively, are achieved, benefit from ultrahigh susceptibility GaSe, resonance enhanced GaSe-light interaction, phase-matching condition satisfied mode engineering. Combining easy integration, GaSe-assisted offer new route to enriching already strong functionality optics.