Theory of second-harmonic generation in a chirped 2D nonlinear optical superlattice under nonlinear Raman-Nath diffraction

Abstract

We analyze second harmonic generation (SHG) in a two dimensional nonlinear optical superlattice (NLOS) with its modulation period being chirped in the propagation direction and constant in the transverse direction. This results in efficient multiple SHG via nonlinear Raman-Nath diffraction. We obtain exact analytical expressions for a SH amplitude generated in chirped 2D NLOSs and for its quasi-phasematching bandwidth. The results of analytical calculations are in excellent agreement with the numerical ones. We show that the process is robust to angular deviations of NLOS and it can be applied to enable tunable and broadband frequency conversion.

Theory of noncollinear frequency doubling of transform limited pulses in non-steady-state regime

“…It has been shown that the fundamental pulse duration can be readily characterized with single pulses by means of measuring the second harmonic beam profile by a spatial detector. The approach proposed can be used to calculate parametric interactions in oneand two-dimensional nonlinear photonic crystals [19,20]. …”

Multiple nonlinear Bragg diffraction of femtosecond laser pulses in a ${\chi^{(2)}}$ photonic lattice with hexagonal domains

“…They have been found to be promising for multiwavelength generation [8], the implementation of broadband parametric interactions [9], producing path-entangled photons [10] and multiple copies of beams carrying orbital angular momentum [11], and the observation of the nonlinear Talbot effect [12,13]. Up to now, 2D nonlinear photonic lattices with periodic [14], randomized [15], superimposed [16], and chirped [17] modulation of the nonlinear susceptibility sign in the propagation direction have been investigated. Among them, only periodic structures provide a specific reciprocal lattice vector for all the NRND orders, while the phase mismatches for different orders are different.…”

Theoretical study on broadband second harmonic generation in periodically and aperiodically poled KTP

“…One of these is to use the dispersion property of QPM materials to obtain broadband QPM SHG with groupvelocity matching [1][2][3][4] (GVM) between the fundamental harmonic (FH) and second harmonic (SH) waves in periodically poled nonlinear crystals. Another method is to compensate the phase mismatch between interactive light waves through chirped nonlinear crystals, such as chirped periodically poled crystals [5,6], apodized chirped crystals [7], Bessel-chirped crystals [8] and chirped 2D nonlinear crystals [9]. Although these methods can broaden the acceptance bandwidth effectively, the acceptance bandwidth is still restricted in certain ranges.…”