Generation and properties of dissipative Kerr solitons and platicons in optical microresonators with backscattering.

Generation and properties of dissipative Kerr solitons and platicons in optical microresonators are studied in the presence of the backscattering using the original analytical model considering a linear forward-backward waves coupling and nonlinear cross-action. We reveal that the backscattering may suppress the generation of the solitonic pulses or destabilize them for both anomalous and normal group velocity dispersion. We also demonstrate the possibility of switching between different soliton states. The influence of the linear and nonlinear coupling is analysed. It is shown that while the impact of the nonlinear coupling on the generation of the bright solitons is rather weak, it is significantly more pronounced for the platicon excitation process.

Spectrum collapse, narrow linewidth, and Bogatov effect in diode lasers locked to high-Q optical microresonators.

We present a novel method allowing high-power single-frequency emission with sub-kHz linewidth from a compact multi-frequency diode laser locked to high-Q optical microresonator. Using high-Q MgF2microresonator and multi-frequency diode laser operating at 1535 nm with the output power of 100 mW and an emission spectrum consisting of approximately 50 lines with MHz linewidth, we observed a spectrum collapse to a single line or several lines with a sub-kHz linewidth and output power power of 50 mW. The Bogatov effect predicted more than 30 years ago was observed and studied in the spectrum of the locked laser. For analysis of the considered effect, original theoretical model taking into account self-injection locking effect, mode competition and Bogatov asymmetric mode interaction was developed and numerical modeling was performed. All numerical results are in a good agreement with our experimental data. Accurate analytical estimations for the parameters critical for the considered effect were obtained. The proposed method may be applied for different types of diode lasers operating in different spectral ranges.

Raman-Kerr frequency combs in microresonators with normal dispersion.

We generalize the coupled mode formalism to study the generation of frequency combs in microresonators with simultaneous Raman and Kerr nonlinearities and investigate an impact of the former on the formation of frequency combs and dynamics of platicons in the regime of the normal group velocity dispersion. We demonstrate that the Raman effect initiates generation of sidebands, which cascade further in four-wave mixing and reshape into the Raman-Kerr frequency combs. We reveal that the Raman scattering induces a strong instability of the platicon pulses associated with the Kerr effect and normal dispersion. This instability results in branching of platicons and complex spatiotemporal dynamics.

Soliton dual frequency combs in crystalline microresonators.

We present a novel compact dual-comb source based on a monolithic optical crystalline MgF2 multi-resonator stack. The coherent soliton combs generated in the two microresonators of the stack with the repetition rate of 12.1 GHz and difference of 1.62 MHz provided after heterodyning a 300 MHz wide radio frequency comb. An analogous system can be used for dual-comb spectroscopy, coherent LIDAR applications, and massively parallel optical communications.