Cascaded third-harmonic generation of ultrashort optical pulses in two-dimensional quasi-phase-matching gratings

Nonlinear Cascaded Femtosecond Third Harmonic Generation by Multi-grating Periodically Poled MgO-doped Lithium Niobate

“…The main peak of the TH spectrum appears at 508.9 nm with a FWHM of 8.7 nm and another peak locates at 516.1 nm. The TH spectral width is more than two times as the reported value of 4 nm by the cascaded THG of 118 fs pump pulses with a FWHM of 51 nm in the two-dimension PPLN [8]. The measured TH mode in the output face of the sample is shown in inset of Figure 3(b).…”

“…During the cascaded processes, the TH bandwidth is limited by GVM among fundamental, SH and TH pulses. However, the GVM between the fundamental and SH pulses is the most important because it directly determines the effective interaction length of the SFG process [8]. In our experiment, the small GVM between the fundamental and SH pulses mainly results in the generation of the broadband TH wave.…”

“…As the input power increases, the SH power increases linearly and the TH power increases quadratically. The THG efficiency saturation has been observed at the intensity level of 20 GW/cm 2 in the femtosecond cascaded THG [8]. When the intensity is raised to the order of magnitude of 100 GW/cm 2 , the THG efficiency can't keep constant.…”

“…However, there are few reports on cascaded THG of ultrashort pulses. N. Fujioka realized noncollinear cascaded THG of femtosecond pulses using two-dimension periodically poled lithium niobate and THG efficiency of 8% with spectral width of 4 nm was obtained [8].…”

Nonlinear optical properties of a two-dimensional nonlinear photonic quasicrystal based on second order cascaded nonlinearities

“…The QPM method compensates the phase mismatches by providing reciprocal vectors, and ensures multiple nonlinear optical processes could be realized on one chip. Varieties of structures based on QPM have been developed and applied in nonlinear optics, such as one-dimensional (1D) [5,6] and two-dimensional (2D) periodic crystals [7][8][9] and nonlinear photonic quasicrystals. Two-dimensional nonlinear photonic quasicrystals (2DNPQC) can provide a wider range of reciprocal vectors than 1D structures, that are available to realize multiple secondorder cascaded nonlinearities.…”