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

Abstract

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

Two-dimensional semiconducting SnP2Se6 with giant second-harmonic-generation for monolithic on-chip electronic-photonic integration

“…By fitting the resonance dips with Lorentzian line shapes, the Q factor of the resonance modes is calculated to be 1000. It should be noted that the resonance dips would red-shift by 1.7 nm after SnP 2 Se 6 overlapping, which is attributed to the perturbation of resonance modes arised from the high refractive index of SnP 2 Se 6 7 . As expected, strong optical signals around 780 nm were collected from the output grating coupler by exciting SnP 2 Se 6 nanosheet from the SiN microring resonator.…”

“…Benefiting from the odd-even layer-independent SHG activity and high SHG susceptibility at telecom wavelength, multilayer SnP 2 Se 6 with sufficient thickness for high-efficient frequency conversion can be integrated into SiN photonic platform, thus enabling the design of on-chip optical modulator 14 . Compared with the free-space interaction mode, a remarkable enhancement of SHG process can be expected by integrating 2D NLO materials into photonic microring resonator due to strong light-matter coupling effect 7 . Figure 5a displays the OM image of a SiN photonic structure for on-chip SHG, in which two bus-waveguides are coupled with a SiN microring resonator.…”

“…The up-converted SHG signals was finally collected from the output grating coupler, with an estimated power of P SHG = 55 nW. Therefore, the conversion efficiency ( η ) of SHG can be calculated through the following equation 7 , 38 : The maximum value of 43.2%W −1 can be obtained for a sample with thickness about 21 nm, which is reasonably satisfying for our experimental setup and notable in previously reported TMDCs-integrated photonic structures 11 , 39 .…”

“…For the 2D semiconductors with the capability of nonlinear optical (NLO) wavelength conversion, and in particular, the second-harmonic generation (SHG), output signal can be generated with frequency doubled from the incident photon field, which occurs in the crystal with intrinsically broken inversion symmetry 4 – 6 . The hybrid silicon photonics integrated with 2D NLO materials have proven to be an ideal platform for the implementation of on-chip optical modulation and signal processing 7 , 8 . By combining the strong NLO activity with excellent optoelectronic properties of 2D NLO semiconductors, one can expect the accomplishment of integrated multi-functions required for monolithic on-chip electronic-photonic integrated circuits (EPICs), such as light generation 9 , 10 , frequency conversion 11 , 12 , nonlinear electro-optic modulation 13 , 14 , photodetection and compact on-chip optoelectronic integration 3 , 15 , 16 .…”

Second Harmonic Generation Control in 2D Layered Materials: Status and Outlook

“…Except for the above-mentioned studies, dielectric nanostructures with other various configurations such as subwavelength patterned TMDs surfaces, [362] dielectric microspheres [373] or microring [374] and dielectric substrates, [375,376] etc. can also be used to tune the nonlinear response of 2DLMs.…”