arXiv subjects

Evgeni Sorokin

Publications and source records attributed to Evgeni Sorokin.

17 recordsLinked to original sources

arXiv2025

Driven Dissipative Soliton Resonance

We investigate the enhancement of the dissipative soliton energy scalability by the injection of a low-power single-mode seed synchronized with a chirped-pulse oscillator round-trip. It is demonstrated that a threshold-like transition to multiple-pulse generation limits the maximum energies of dissipative solitons, in agreement with the thermodynamic interpretation of a strongly chirped pulse stability. We show that there are ``islands'' of instability within a stability range of energies which result from stochastic resonance between ``internal modes'' of soliton and quantum noise of the ``basin''. The transition to multiple-pulsing can be suppressed in a system driven by a comparatively low-power seed. However, seed power growth increases the mode-locking energy threshold and produces ``islands'' of instability as the dissipative soliton energy rises.

physics.optics↗

arXiv2025

Energy Scalability Limits of Dissipative Solitons

In this study, we apply a thermodynamical approach to elucidate the primary constraints on the energy scaling of dissipative solitons (DS). We rely on the adiabatic theory of strongly chirped DS and define the DS energy scaling in terms of dissipative soliton resonance (DSR). Three main experimentally verifiable signatures identify a transition to DSR: i) growth of a Lorentzian spike at the centrum of the DS spectrum, which resembles a spectral condensation in Bose-Einstein condensate (BEC), ii) saturation of the spectrum broadening, and iii) asymptotical DS stretching. We connect the DSR breakup with three critical factors: i) decoupling of two correlation scales inherent in strongly chirped DS, ii) resulting rise of the DS entropy with energy, which provokes its disintegration, and iii) transition to a nonequilibrium phase, which is characterized by negative temperature. The breakup results in multiple stable DSs with lower energy. Theoretical results are in good qualitative agreement with the experimental data from a Kerr-lens mode-locked Cr$^{2+}$:ZnS chirped-pulse oscillator (CPO) that paves the way for optimizing high-energy femtosecond pulse generation in solid-state CPO and all-normal-dispersion fiber lasers.

physics.optics↗

arXiv2024

Chirped pulse waveguide amplifier

We introduce a single-mode Cr:ZnS crystalline waveguide ultrafast amplifier that provides a high gain of 5.5 dB/cm and 2.35 W of average output power. The depressed-cladding buried waveguide is produced by an ultrafast laser writing procedure, which allows a high degree of flexibility in fabrication when the geometry, size, and even effective index can be modified along the waveguide. An analytical model that includes both, pump and pulse propagation, allows calculation and optimization of the waveguide design. In a CPA arrangement with a volume Bragg grating-based stretcher/compressor, we demonstrate a broadband 34-mm long amplifier in a polycrystalline Cr:ZnS with a single-pass gain factor of 75 (5.5 dB/cm) and a high average output power up to 2.35 W.

physics.optics↗

arXiv2024

Dissipative spatiotemporal soliton in a driven waveguide laser

A distributed Kerr-lens mode locking regime can be realized in a waveguide laser by spatial profiling of the pump beam, thus creating a spatio-temporal soliton. Additional slow temporal modulation of the pump source stabilizes the spatio-temporal solution in a broad range of parameters, which are defined by the dynamic gain saturation. We choose a Cr:ZnS waveguide laser as a practical example, but such a regime is feasible in various waveguide and fiber oscillators. A far-reaching analogy with Bose-Einstein condensates allows using this approach to stabilization of the weakly dissipative BECs.

physics.optics↗

arXiv2024

Dissipative Soliton Resonance: Adiabatic Theory and Thermodynamics

We present the adiabatic theory of dissipative solitons (DS) of complex cubic-quintic nonlinear Ginzburg-Landau equation (CQGLE). Solutions in the closed analytical form in the spectral domain have the shape of Rayleigh-Jeans distribution for a positive (normal) dispersion. The DS parametric space forms a two-dimensional (or three-dimensional for the complex quintic nonlinearity) master diagram connecting the DS energy and a universal parameter formed by the ratio of four real and imaginary coefficients for dissipative and non-dissipative terms in CQGLE. The concept of dissipative soliton resonance (DSR) is formulated in terms of the master diagram, and the main signatures of transition to DSR are demonstrated and experimentally verified. We show a close analogy between DS and incoherent (semicoherent) solitons with an ensemble of quasi-particles confined by a collective potential. It allows applying the thermodynamical approach to DS and deriving the conditions for the DS energy scalability.

nlin.PS↗

arXiv2023

A route to high peak power and energy scaling in the mid-IR chirped-pulse oscillator-amplifier laser systems

The paper introduces a new route towards the ultrafast high laser peak power and energy scaling in a hybrid mid-IR chirped pulse oscillator-amplifier (CPO-CPA) system, without sacrificing neither the pulse duration nor energy. The method is based on using a CPO as a seed source allowing the beneficial implementation of a dissipative soliton (DS) energy scaling approach, coupled with a universal CPA technique. The key is avoiding a destructive nonlinearity in the final stages of an amplifier and compressor elements by using a chirped high-fidelity pulse from CPO. Our main intention is to realize this approach in a Cr2+:ZnS-based CPO as a source of energy-scalable DSs with well-controllable phase characteristics for a single-pass Cr2+:ZnS amplifier. A qualitative comparison of experimental and theoretical results provides a road map for the development and energy scaling of the hybrid CPO-CPA laser systems, without compromising pulse duration. The suggested technique opens up a route towards extremely intense ultra-short pulses and frequency combs from the multi-pass CPO-CPA laser systems that are particularly interesting for real-life applications in the mid-IR spectral range from 1 to 20 um.

physics.optics↗

arXiv2023

At the threshold of distributed Kerr-lens mode-locking in a Cr:ZnS waveguide laser

We demonstrate feasibility of spatiotemporal mode-locking in a mid-IR Cr:ZnS waveguide laser based on the nonlinear spatial mode coupling. The experiment shows efficient power scaling with the excitation of intra-mode beatings, causing a pronounced Q-switching which could cause a nonlinear mode-coupling. We suggest that a particularly high nonlinearity in Cr:ZnS combined with multimode waveguide leads to a soft aperture induced by a pump beam. The latter provides an effective spatial mode control in a nonlinear multimode waveguide and, thereby, opening the way to the birth of a spatiotemporal dissipative soliton, or light bullet, formation. Thus, forming the basis for the future distributed Kerr-Lens Mode Locking in the energy-scalable solid-state waveguide (or yet unrealized fiber) laser.

physics.optics↗

arXiv2022

Atmospheric dispersion management in the mid-IR mode-locked oscillators

The atmospheric dispersion in the mid-infrared transparency windows presents and important albeit frequently neglected factor when developing ultra-short pulsed lasers. We show that it can amount to hundreds of fs^2 in 2-3 micron window with typical laser round-trip path lengths. Using the Cr:ZnS ultrashort-pulsed laser as a test-bed, we demonstrate the atmospheric dispersion influence on a femtosecond and chirped-pulse oscillator performance and show that the humidity fluctuations can be compensated by active dispersion control, greatly improving stability of mid-IR few-optical cycle laser sources. The approach can be readily extended to any ultrafast source in the mid-IR transparency windows.

physics.optics↗

arXiv2022

High-Power Mid-IR Few-Cycle Frequency Comb from Quadratic Solitons in an Optical Parametric Oscillator

Powerful and efficient optical frequency combs in the mid-infrared (MIR) spectral region are highly desirable for a broad range of applications. Despite extensive efforts utilizing various techniques, MIR frequency comb sources are still lacking power, efficiency, or bandwidth for many applications. Here, we report the generation of an intrinsically locked frequency comb source centered at 4.18 μm from an optical parametric oscillator (OPO) operating in the simulton regime, in which formation of purely quadratic solitons lead to enhanced performance. We show advantages of operation in the simulton regime in direct experimental comparisons to the conventional regime, which are also supported by simulation and theory. We achieve 565 mW of average power, 900 nm of instantaneous 3-dB bandwidth, 350% of slope efficiency, and 44% of conversion efficiency; a performance that is superior to previous OPO demonstrations and other sources in this wavelength range. This work opens a new avenue toward MIR frequency comb generation with high power and efficiency and suggests the great potential of soliton generation based on quadratic nonlinearity in the MIR spectral region.

physics.optics↗

arXiv2020

Sub-surface modifications in silicon with ultrashort pulsed lasers above 2 microns

Nonlinear optical phenomena in silicon such as self-focusing and multi-photon absorption are strongly dependent on the wavelength, energy and duration of the exciting pulse. Thus, a pronounced wavelength dependence of the sub-surface modifications with ultra-short pulsed lasers exists, especially for wavelengths > 2 $μ$m. This wavelength dependence is investigated for wavelengths in the range of 1950-2400 nm, at a pulse duration between 0.5-10 ps and the pulse energy varying from 1 $μ$J to 1 mJ. Numerical and experimental analyses have been performed on both the surface and sub-surface of Si wafers processed with fibre-based lasers built in-house that operate in this wavelength range. The results have been compared to the literature data at 1550 nm. The analysis carried out has shown that due to a dip in the nonlinear absorption spectrum and a peak in the spectrum of the third-order non-linearity, the wavelengths between 2000 - 2200 nm are more favourable for creating sub-surface modifications in silicon. This is the case even though those wavelengths do not allow as tight a focusing as those at 1550 nm in the linear regime. This problem is compensated by an increased self-focusing due to the nonlinear Kerr-effect around 2100 nm at high light intensities, characteristic for ultra-short pulses.

physics.optics↗

arXiv2008

Mode-locked oscillators in the positive and negative dispersion regimes: scenarios of destabilization

We analyze the influence of spectrally modulated dispersion and loss on the stability of mode-locked oscillators. In the negative dispersion regime, a soliton oscillator can be stabilized in a close proximity to zero-dispersion wavelength, when spectral modulation of dispersion and loss are strong and weak, respectively. If the dispersion is close to zero but positive, we observe chaotic mode-locking or a stable coexistence of the pulse with the CW signal. The results are confirmed by experiments with a Cr:YAG oscillator.

physics.optics↗

arXiv2007

Supercontinua for high resolution absorption multiplex infrared spectroscopy

Supercontinua generated in highly non-linear fibers by ultrashort-pulse lasers can be used for high resolution Fourier transform absorption spectroscopy. The practical advantages of these bright ultrabroadband light sources for spectroscopy are reported in the near-infrared region. A Cr^4+:YAG femtosecond laser broadened by an extruded soft-glass photonic crystal fiber, emitting from 1200 to 2200 nm and from 675 to 950 nm, provides a spectral radiance being 1x10^5 times higher than that of a 3000 K blackbody and 10^2 times higher than that of a synchrotron radiation. The C_2H_2 and NH_3 overtone spectra are recorded using this source within a few seconds.

physics.optics↗

arXiv2007

Infrared frequency combs and supercontinua for multiplex high sensitivity spectroscopy

An infrared high-brightness light source based on supercontinuum generation through a SF6 photonic crystal fiber seeded by a Cr^4+:YAG femtosecond oscillator is developed for high resolution multiplex spectroscopy in the 1.5 $μ$m region. Moreover, a multiplex high resolution approach based on a Cr^4+:YAG frequency comb enables to probe large spectral domains, with simultaneous sensitive measurement of the absorption and the dispersion associated with all individual spectral features.

physics.optics↗

arXiv2007

Sensitive multiplex spectroscopy in the molecular fingerprint 2.4 $μ$m region with a Cr^{2+}:ZnSe femtosecond laser

An ultrashort-pulse Cr^{2+}:ZnSe laser is a novel broadband source for sensitive high resolution molecular spectroscopy. A 130-fs pulse allows covering of up to 380 cm^-1 spectral domain around 2.4 $μ$m which is analyzed simultaneously with a 0.12 cm^-1 (3.6 GHz) resolution by a Fourier-transform spectrometer. Recorded in 13 s, from 70-cm length absorption around 4150 cm^-1, acetylene and ammonia spectra exhibit a 3800 signal-to-noise ratio and a 2.4*10^-7 cm^-1*Hz^-1/2 noise equivalent absorption coefficient at one second averaging per spectral element, suggesting a 0.2 ppbv detection level for HF molecule. With the widely practiced classical tungsten lamp source instead of the laser, identical spectra would have taken more than one hour.

physics.optics↗

arXiv2006

N_2O weak lines observed between 3900 and 4050 cm^-1 from long path absorption spectra

Previously unobserved nitrous oxide transitions around 2.5 $μ$m are measured by intracavity laser absorption spectroscopy (ICLAS) analyzed by time-resolved Fourier transform (TRFT) spectrometer. With an accuracy of the order of 10^-3 cm^-1, measured positions of 1637 assigned weak transitions are provided. They belong to 42 vibrational transitions, among which 33 are observed for the first time. These data are believed to be useful in particular to monitoring atmosphere purposes.

physics.chem-ph↗

arXiv2006

Acetylene weak bands at 2.5 $μ$m from intracavity Cr2+:ZnSe laser absorption observed with time-resolved Fourier transform spectroscopy

The spectral dynamics of a mid-infrared multimode Cr^2+:ZnSe laser located in a vacuum sealed chamber containing acetylene at low pressure is analyzed by a stepping-mode high-resolution time-resolved Fourier transform interferometer. Doppler-limited absorption spectra of C_2H_2 in natural isotopic abundance are recorded around 4000 cm^-1 with kilometric absorption path lengths and sensitivities better than 3 10^-8 cm-1. Two cold bands are newly identified and assigned to the n_1+n_4^1 and n_3+n_5^1 transitions of ^12C^13CH_2. The n_1+n_5^1 band of ^12C_2HD and fourteen ^12C_2H_2 bands are observed, among which for the first time n_2+2n_4^2+n_5^-1.

physics.chem-ph↗

arXiv2006

Time-resolved Fourier transform intracavity spectroscopy with a Cr2+:ZnSe laser

Intracavity laser absorption spectroscopy (ICLAS) with an evacuated Cr2+: ZnSe laser is performed with a high-resolution time-resolved Fourier transform interferometer with a minimum detectable absorption coefficient equal to 4 10-9 cm-1 Hz-1/2 in the 2.5$μ$m region. This represents the extreme limit presently reached in the infrared by ICLAS with Doppler limited resolution. The broad gain band of the crystal allows a spectral coverage at most equal to 125 nm, wide enough to see entire vibration bands. Weak CO2 bands observed up to now only in the Venus atmosphere are recorded for the first time in a laboratory. H2O detection limit down to 0.9 ppbv is also demonstrated.

physics.optics↗