Temporal Simultons in Optical Parametric Oscillators

Abstract

We report the first demonstration of a regime of operation in optical parametric oscillators (OPOs), in which the formation of temporal simultons produces stable femtosecond half-harmonic pulses. Simultons are simultaneous bright-dark solitons of a signal field at frequency ω and the pump field at 2ω, which form in a quadratic nonlinear medium. The formation of simultons in an OPO is due to the interplay of nonlinear pulse acceleration with the timing mismatch between the pump repetition period and the cold-cavity roundtrip time and is evidenced by sech 2 spectra with broad instantaneous bandwidths when the resonator is detuned to a slightly longer round-trip time than the pump repetition period. We provide a theoretical description of an OPO operating in a regime dominated by these dynamics, observe the distinct features of simulton formation in an experiment, and verify our results with numerical simulations. These results represent a new regime of operation in nonlinear resonators, which can lead to efficient and scalable sources of few-cycle frequency combs at arbitrary wavelengths. DOI: 10.1103/PhysRevLett.120.053904 Introduction.-The temporal modes that arise from cavity nonlinear dynamics have attracted intense interest due to both their diversity of operating regimes and their applications. Recent work has focused on resonators with cubic nonlinearities that form dissipative solitons from a balance between intracavity dispersion and self-phase modulation [1][2][3]. These systems have successfully generated few-cycle pulses and phase-stabilized frequency combs in the range from 400 nm to 3.5 μm [4-6] and have been employed in optical clocks [7], spectroscopy [8], telecommunications [9], and attoscience [10]. While considerable effort is being invested to extend these sources to other wavelength ranges [11], such operation requires overcoming the challenges associated with developing broadband laser gain media and high finesse resonators at new wavelengths.Nonlinear resonators based on quadratic nonlinearities offer a compelling new direction for the field. In contrast with cubic nonlinearities, the χ ð2Þ associated with quadratic nonlinearities may be patterned to quasiphasematch a rich variety of multiwave interactions. χ ð2Þ materials are well developed and frequently used to produce pulses at otherwise inaccessible wavelengths, but many of the regimes of operation in these systems remain relatively unexplored. One promising system is the synchronously pumped degenerate optical parametric oscillator (OPO), in which a χ ð2Þ resonator pumped at 2ω generates a resonant halfharmonic at ω. While many pulse formation mechanisms have been proposed in continuous-wave-pumped degenerate OPOs [12][13][14][15], to date these systems have not yet achieved mode-locked femtosecond pulses by using such

Ultrabroadband nonlinear optics in nanophotonic periodically poled lithium niobate waveguides

“…To better understand the dynamics and coherence properties of the generated supercontinuum, we simulate Eqns. (2a-2b) using the split-step fourier method described in [29], including dispersion to third order. The experimentally measured and simulated spectra output from the waveguide are shown in Figures 5(a) and 5(b), respectively.…”

Nonlinear solutions for χ(2) frequency combs in optical microresonators

“…Attempts to explore χ (2) frequency combs regardless of solitons are reported in [21][22][23][24]. Also, the so-called simultonsolitons are reported recently for meter-scale parametric oscillators [25]. The area remains, in essence, largely unexplored.…”

Quadratic Solitons in Singly Resonant Degenerate Optical Parametric Oscillators

“…Synchronously pumped degenerate OPOs (DOPOs) based on periodically poled Lithium niobate (PPLN) [13][14][15] and orientation-patterned gallium arsenide (OP-GaAs) [16,17] have all been successfully implemented as viable MIR OFC sources. In addition, a new operation regime of a near-synchronously pumped DOPO has been observed recently in which temporal simultons are formed through the balance between synchronization timing mismatch and nonlinear pulse acceleration [18].…”