Detuning-dependent properties and dispersion-induced instabilities of temporal dissipative Kerr solitons in optical microresonators

Temporal-dissipative Kerr solitons are self-localized light pulses sustained in driven nonlinear optical resonators. Their realization in microresonators has enabled compact sources of coherent optical frequency combs as well as the study of dissipative solitons. A key parameter of their dynamics is the effective detuning of the pump laser to the thermally and Kerr-shifted cavity resonance. Together with the free spectral range and dispersion, it governs the soliton-pulse duration, as predicted by an approximate analytical solution of the Lugiato-Lefever equation. Yet a precise experimental verification of this relation has been lacking so far. Here, by measuring and controlling the effective detuning, we establish a way of stabilizing solitons in microresonators and demonstrate that the measured relation linking soliton width and detuning deviates by less than 1% from the approximate expression, validating its excellent predictive power. Furthermore, a detuning-dependent enhancement of specific comb lines is revealed due to linear couplings between mode families. They cause deviations from the predicted comb power evolution and induce a detuning-dependent soliton recoil that modifies the pulse repetition rate, explaining its unexpected dependence on laser detuning. Finally, we observe that detuning-dependent mode crossings can destabilize the soliton, leading to an unpredicted soliton breathing regime (oscillations of the pulse) that occurs in a normally stable regime. Our results test the approximate analytical solutions with an unprecedented degree of accuracy and provide insights into dissipative-soliton dynamics.

Intermode Breather Solitons in Optical Microresonators

Miles Henry Anderson, Michael Wolfgang Geiselmann, Hairun Guo, John David Jost, Maxim Karpov, Tobias Kippenberg, Junqiu Liu, Erwan Guillaume Albert Lucas, Martin Hubert Peter Pfeiffer

Dissipative solitons can be found in a variety of systems resulting from the double balance between dispersion and nonlinearity, as well as gain and loss. Recently, they have been observed to spontaneously form in Kerr nonlinear microresonators driven by a continuous wave laser, providing a compact source of coherent optical frequency combs. As optical microresonators are commonly multimode, intermode interactions, which give rise to avoided mode crossings, frequently occur and can alter the soliton properties. Recent works have shown that avoided mode crossings cause the soliton to acquire a single-mode dispersive wave, a recoil in the spectrum, or lead to soliton decay. Here, we show that avoided mode crossings can also trigger the formation of breather solitons, solitons that undergo a periodic evolution in their amplitude and duration. This new breather soliton, referred to as an intermode breather soliton, occurs within a laser detuning range where conventionally stationary (i.e., stable) dissipative Kerr solitons are expected. We experimentally demonstrate the phenomenon in two microresonator platforms (crystalline magnesium fluoride and photonic chip-based silicon nitride microresonators) and theoretically describe the dynamics based on a pair of coupled Lugiato-Lefever equations. We show that the breathing is associated with a periodic energy exchange between the soliton and a second optical mode family, a behavior that can be modeled by a response function acting on dissipative solitons described by the Lugiato-Lefever model. The observation of breathing dynamics in the conventionally stable soliton regime is relevant to applications in metrology such as low-noise microwave generation, frequency synthesis, or spectroscopy.

2017

Study on the detuning-dependent properties of a temporal dissipative Kerr soliton in an optical microresonator

John David Jost, Tobias Kippenberg, Erwan Guillaume Albert Lucas

Temporal dissipative Kerr solitons in a continuous-wave laser-driven nonlinear optical microresonator enable compact, high-repetition rate sources of ultrashort pulses and coherent broadband optical frequency combs. A central parameter in the soliton formation process, is the effective detuning of the pump laser to the thermally- and Kerr-shifted cavity resonance, which, together with the free spectral range and dispersion, governs the soliton pulse duration. Here, we introduce a technique to probe, stabilize, and control the effective detuning of a driven nonlinear crystalline resonator while monitoring the dissipative Kerr soliton properties, which enables to study the detuning-dependent soliton properties and accurate comparisons of the theoretical predictions with experiments. We demonstrate that the experimentally measured relation between detuning and soliton duration deviates by less than 1% from the analytical solution, demonstrating its excellent predictive power. In contrast, avoided mode crossings, induced by a linear mode coupling in the resonator mode spectrum, are found to alter the comb profile, leading to a detuning-dependent enhancement or suppression of specific comb lines. This causes deviations from the expected comb power evolution and is shown to induce a detuning-dependent recoil on the soliton, which leads to a modification in the pulse repetition rate. The presented results provide unprecedented precision in the verification of the analytical solutions of such solitons, and provide insights into the detuning dynamics of this class of solitons.

2016

Temporal solitons in optical microresonators

Victor Brasch, Tobias Herr, John David Jost, Tobias Kippenberg

Temporal dissipative solitons in a continuous-wave laser-driven nonlinear optical microresonator were observed. The solitons were generated spontaneously when the laser frequency was tuned through the effective zero detuning point of a high-Q resonance, which led to an effective red-detuned pumping. Transition to soliton states were characterized by discontinuous steps in the resonator transmission. The solitons were stable in the long term and their number could be controlled via pump-laser detuning. These observations are in agreement with numerical simulations and soliton theory. Operating in the single-soliton regime allows the continuous output coupling of a femtosecond pulse train directly from the microresonator. This approach enables ultrashort pulse syntheses in spectral regimes in which broadband laser-gain media and saturable absorbers are not available. In the frequency domain the single-soliton states correspond to low-noise optical frequency combs with smooth spectral envelopes, critical to applications in broadband spectroscopy, telecommunications, astronomy and low noise microwave generation.

Nature Publishing Group2014

Intermode Breather Solitons in Optical Microresonators

Miles Henry Anderson, Michael Wolfgang Geiselmann, Hairun Guo, John David Jost, Maxim Karpov, Tobias Kippenberg, Junqiu Liu, Erwan Guillaume Albert Lucas, Martin Hubert Peter Pfeiffer

2017