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E. Sorokin

Publications and source records attributed to E. Sorokin.

5 recordsLinked to original sources

Strongly chirped dissipative solitons in normal and anomalous dispersion regimes

We study strongly chirped dissipative solitons of the cubic-quintic complex Ginzburg-Landau equation in normal and anomalous group-delay dispersion. Using a stationary-phase (adiabatic) approximation, we derive analytic spectra and construct master diagrams linking the control-parameter ratios (spectral filtering, dispersion, and cubic-quintic self-phase/self-amplitude modulation) to the scaled soliton energy. Dissipative-soliton resonance appears generically in normal dispersion from admissibility constraints, while in anomalous dispersion it occurs only when the resonance locus lies inside the adiabatic existence window, which requires sufficiently strong saturable quintic self-phase modulation. Normal-dispersion spectra are intrinsically truncated, whereas anomalous-dispersion spectra develop a structured, approximately self-similar core (two-horn envelope with smooth wings) with effective truncation set by spectral dissipation; in the energy-scaling regime, the energy dependence is captured mainly by a scalar prefactor while the unit-peak core remains nearly invariant. We further show that anomalous-dispersion coherence separates into an energy-dependent autocorrelation magnitude and an almost invariant normalized coherence shape, revealing two correlation times: a short, bandwidth-limited scale and a long, core-controlled scale. Finally, we outline a thermodynamic interpretation of this scale separation and its implications for single-to-multi-soliton transitions, and discuss how analogous two-scale coherence phenomenology may arise in weakly dissipative Bose-Einstein condensates and in driven optical condensates under bandwidth-limited losses.

nlin.PS

Femtosecond laser writing of the depressed cladding buried channel waveguides in ZnS crystal

We report the first direct femtosecond laser-writing of buried channel waveguides in monocrystalline ZnS. We also report the first single-mode Cr:ZnS depressed cladding buried waveguide laser manufactured by femtosecond laser writing. The laser yields 150 mW average power at 2272 nm wavelength with 11% slope efficiency. A depressed cladding waveguide with propagation loss of 0.62 dB/cm at 1030 nm allowed to obtain spectral broadening under femtosecond-pumping at 1030 nm.

physics.optics

Soliton absorption spectroscopy

We analyze optical soliton propagation in the presence of weak absorption lines with much narrower linewidths as compared to the soliton spectrum width using the novel perturbation analysis technique based on an integral representation in the spectral domain. The stable soliton acquires spectral modulation that follows the associated index of refraction of the absorber. The model can be applied to ordinary soliton propagation and to an absorber inside a passively modelocked laser. In the latter case, a comparison with water vapor absorption in a femtosecond Cr:ZnSe laser yields a very good agreement with experiment. Compared to the conventional absorption measurement in a cell of the same length, the signal is increased by an order of magnitude. The obtained analytical expressions allow further improving of the sensitivity and spectroscopic accuracy making the soliton absorption spectroscopy a promising novel measurement technique.

physics.optics

Spectral Characteristics of Ultrashort Pulses in Kerr-lens Mode-Locked Lasers

A number of factors that influence spectral position of the femtosecond pulse in a Kerr-lens modelocked Cr:LiSGaF laser have been identified: high-order dispersion, gain saturation, reabsorption from the ground state, and stimulated Raman scattering. Using the one-dimensional numerical model for the simulation of the laser cavity, the relative contributions of different factors have been compared. The Raman effect provides the largest self-frequency shift from the gain peak (up to 60 nm), followed by the gain saturation (25 nm), while the high-order dispersion contribution is insignificant (5 nm). Comparison with the experimental data confirm that the stimulated Raman scattering is a main cause of the ultrashort pulse self-frequency shift observed in Cr:LiSGaF and Cr:LiSAF lasers

physics.optics