Quadratic Solitons in Singly Resonant Degenerate Optical Parametric Oscillators

Abstract

By identifying the similarities between the coupled-wave equations and the parametrically driven nonlinear Schrödinger equation, we for the first time unveil the existence condition of quadratic solitons in continuouswave pumped singly resonant degenerate optical parametric oscillators (SR-DOPOs). Compared to the previously explored doubly resonant DOPOs, quadratic solitons in SR-DOPOs are advantageous in their robustness against perturbations induced by dispersion of the effective third-order nonlinearity and temporal walk-off between the signal and the pump. Terahertz comb bandwidth and femtosecond pulse duration are attainable in an example periodically poled Lithium niobate waveguide resonator in the short-wave infrared. The working principle can be extended to other material platforms, making it a competitive ultrashort pulse and broadband comb source architecture at the mid-infrared.

Dissipative localized states and breathers in phase mismatched singly resonant optical parametric oscillators: Bifurcation structure and stability

“…and , d and η 2 are the normalized phase mismatch, group velocity mismatch or walk-off, and group velocity dispersion of the pump field. Here, j R (k) mirror the dispersive two-photon absorption, while the contribution related with j I (k) produces a phase-shift, similar to the Kerr effect [37]. More details about the model In what follows, we first study the features and dynamics of LSs in the absence of walk-off (d = 0), and later, in Sec.…”

“…For d = 0, the nonlocal response J depends only on and η 2 , and two different regimes can be identified depending on the sign of η 2 as reported in [37]. In this work, we focus on the regime η 2 < 0, where j R (k) and j I (k) vary periodically with , as shown in [37]. Therefore, we fix = −4 ≈ −1.27π and η 2 > 0.…”

“…Recently, pure quadratic dispersive cavities attracted renewed attention due to their multiple advantages for frequency combs generation [25][26][27][28][29][30]. Since then, different theoretical studies have tackled the investigation of light localization in either cavity enhanced second-harmonic generation [31][32][33] or in degenerate optical parametric oscillators (DOPOs) [34][35][36][37][38].…”

“…The effective Kerr nonlinearity, inherent to mismatched quadratic processes [42], supports the formation of LSs which are absent in the phase-matched configuration. The presence of sech pulses in phase-mismatched OPOs have already been investigated, both in the singly resonant [37,38] and in the doubly resonant [17,24] configurations. In this paper, we focus on the former and investigate the range of existence and stability of these solitons as well as uncover the presence of other LSs.…”

Dark quadratic localized states and collapsed snaking in doubly resonant dispersive cavity enhanced second harmonic generation

“…In quadratic cavities, LS formation has been intensely studied, mainly in the context of optical parametric oscillators (OPOs), both in diffractive [8][9][10][11][12][13][14][15][16][17][18][19][20][21] and dispersive cavities [22][23][24][25]. Cavity enhanced second-harmonic generation (SHG) has received, however, much less attention than OPOs.…”