Nonlinear optics in gallium phosphide cavities: simultaneous second and third harmonic generation

Abstract

We demonstrate the simultaneous generation of second and third harmonic signals from a telecom wavelength pump in a gallium phosphide (GaP) microdisk. Using analysis of the power scaling of both the second and third harmonic outputs and calculations of nonlinear cavity mode coupling factors, we study contributions to the third harmonic signal from direct and cascaded sum frequency generation processes. We find that despite the relatively high material absorption in GaP at the third harmonic wavelength, both of these processes can be significant, with relative magnitudes that depend closely on the detuning between the second harmonic wavelengths of the cavity modes.

Boosted Second Harmonic Generation and Cascaded Sum Frequency Generation from a Surface Crystallized Glass Ceramic Microcavity

“…This observation intricates their interaction prevents the formation of a clear cubic relationship between TH intensity and pump power, as observed in direct third harmonic generation. [ 27 ] CSFG was also found in bulk samples in the 1400–1600 nm wavelength range, but the signal intensity was very weak (see Figure S14, Supporting Information for details). Thanks to the resonance of microcavity, the CSFG signal intensity of the microsphere was 100 times stronger than that of the cross section under the 1500 nm pump with the same power of 1 mW, as shown in Figure 4d.…”

Fast Simulation of Light Scattering and Harmonic Generation in Axially Symmetric Structures in COMSOL

“…From the early years of nonlinear optics, second- and higher-harmonic generation was rightly regarded as an effective tool for frequency conversion. Meanwhile, developing efficient subwavelength sources of SHG is still one of the topical problems of experimental and theoretical nanophotonics. ,− Solution of the SHG problem even in the simplest geometries such as spherical scatterer and plane wave excitation (Mie geometry) is a complex problem, ,, and numerical methods play a crucial role in designing nanophotonic systems. The axial symmetry of the scatterers allows for significantly speeding up the simulations of the SHG by using the azimuthal expansion method.…”

Investigation of χ (2)-Translated Optical Frequency Combs Tunability in Gallium Phosphide-on- Insulator Resonators

“…Due to the 4 ̅ 3𝑚 symmetry of (100)-normal GaP crystal, the effective nonlinear susceptibility changes sign every 90° in the wafer plane as shown in Fig. 2, therefore, the cyclic phase-matching condition ought to be used to avoid back conversion [17], [23]. For an axial-symmetric microring structure, the cyclic phase-matching condition of the SFG process manifests itself through the azimuthal mode numbers as follows:…”