CAOL . International Conference on Advanced Optoelectronics and Lasers

Theoretical review of integrated SRS-RL process in multiple scattering media

Vasil P. Yashchuk, A. A. Sukhariev, A.P. Smaliuk

Published Sep 1, 2016• 0 citations

Abstract

The article studies formation of combined field of stimulated Raman scattering (SRS) radiation and random lasing (RL) of the dyes assisted by nonlinear wave equation that counts amplification on the electronic transition of the molecule. Received relation for SRS's lines intensity and form is consistent with experimental data. It is confirmed that the cause of spectrum's sharpening is an interference of radiation of the adjacent lines.

DOI: 10.1109/caol.2016.7851439

Related papers

Coupled effect of stimulated Raman scattering and random lasing of dyes in multiple scattering medium

Vasil P. Yashchuk

Random lasing (RL) and stimulated Raman scattering (SRS) of dye in multiple scattering media (MSM) appears simultaneously and each couple with other. This coupling has considerable influence on the SRS regularities of dye in MSM. The main feature of this impact is that RL radiation promotes the Raman lines revealing in the RL spectrum range as part of total radiation. SRS initiation occurs owing to the CARS-like mechanism provided by the two component pump: incident monochromatic radiation (laser pump) and RL radiation arising inside the MSM. It leads to important consequences: the RL spectrum must overlap with the spectral region of the possible Stokes lines of the dye; only those Stokes lines appear which are in a range of the RL spectrum; all conditions which promote RL assist SRS also. It is shown MSM promotes the best conditions for SRS and RL coupling due to optimal matching of RL localization regions and pump radiation.

Laser PhysicsJun 29, 201518 citations

Coupling of random lasing and stimulated Raman scattering in a random media: Necessary conditions

Vasil P. Yashchuk, A.P. Smaliuk, Eugene A. Tikhonov

Random lasing (RL) in disordered active media can initiate stimulated Raman Scattering (SRS). We have found the optimal condition of SRS-RL coupling, which is perspective for Raman spectroscopy applications.

Frontiers in OpticsJan 1, 20201 citation

Multifrequency Stimulated Raman Scattering on Rotational Transitions of Molecules

Victor P. Kochanov

Abstract The theory of multifrequency stimulated Raman scattering (SRS) of light on rotational transitions of molecules, which are simulated by a three-level quantum system, is developed. It is shown that the application of bichromatic pumping increases the scattered radiation spectrum width. The exact algebraic solution for the wave amplitudes is obtained in the simplest version of synchronous SRS on transitions with a negligibly low eigenfrequency. It is found that an increase in the ratio of the Raman transition frequency to the pump radiation frequency leads to predominance of the anti-Stokes scattering branch. The effect of wave asynchronism emerging due to linear and nonlinear dispersion of the medium as well as the phase difference of the pump waves on SRS is considered. All types of asynchronism narrow generated frequency spectrum and suppress the anti-Stokes scattering branch. Nonlinear dispersion ensures positive values of wave amplitudes due to phase jumps by π during the propagation of waves in a medium.

Journal of Experimental and Theoretical PhysicsJan 1, 20191 citation

Stimulated Raman scattering spectra: quantum fluctuations and time evolution of linewidth

Владимир Григорьевич Беспалов

Manifestations of quantum fluctuations in stimulated Raman scattering ( SRS ) have been intensively studied lately1. Quantum noise present in spontaneous scattering stimulates fluctuations both in phase and in amplitude characteristics of output Stokes emission. At present statistical properties of amplitude fluctuations are studied in detail and it is shown that in linear transient regime of SRS without pump depletion statistical scatter of Stokes energy Es has negative exponential distribution2. In saturation regime of SRS the amplitude fluctuations are almost suppressed simultaneously with pump depletion. The phase fluctuations manifest both in linear and in nonlinear SRS and produce beam pointing fluctuations3, a change in Stokes emission spectra from pulse to pulse4 and cause soliton appearance in Rayleigh component of SRS5. Phase noise is observed in saturation regime due to relation between phases of Stokes and phonon waves which is preserved in processes of stationary and quasistationary SRS amplification. Spectrum phase fluctuations manifest as fine structure of SRS spectrum4, fluctuations of average Stokes frequency and Stokes linewidth fluctuations. The evolution of phase fluctuations in time is determined by the nature of spontaneous scattering and polarization of Raman media and is of great interest as one can follow its development from vacuum modes level to saturation regime. However up to now this problem has not been studied yet.

17th Congress of the International Commission for Optics: Optics for Science and New TechnologySep 1, 19960 citations

Disorder as a Playground for the Coexistence of Optical Nonlinear Effects: Competition between Random Lasing and Stimulated Raman Scattering in Complex Porous Materials

Nicolas Bachelard, Preeti Gaikwad, Rénal V. Backov +2 more

We predict the coexistence and competition of random lasing and stimulated Raman scattering (SRS) in active disordered random media. We develop a simple model that includes both mechanisms coupled to diffusion equation. We find that the prevalence of a nonlinear mechanism over the other is determined by the degree of scattering. This is confirmed experimentally in dye-infiltrated three-dimensional porous silica-based disordered samples, with controllable pore size and transport properties. Experimentally, random lasing dominates in a sample with a large transport mean free path, l t ≈ 100 μm, while it gives way to SRS for l t ≈ 25 μm. The competition is explained in terms of disorder-dependent pump depletion and fluorescence saturation.

ACS PhotonicsOct 14, 201428 citations

a Theoretical Study on the Stimulated Raman Scattering Modulated by the Flopping Frequency Arising from the Interaction Between a Strong Resonant Field and the Medium.

C. J. Hsu

The stimulated Raman scattering (SRS), arising from the interaction between molecules of a medium and two strong light fields - a resonant field and a pumping field - is studied theoretically. The transitions of molecules between a given pair of levels is assumed to be both Raman active and infrared active. A semiclassical approach, in which the density matrix method is used for the quantum mechanical description for the medium, is employed. We expand the density matrix in various orders within which the zeroth-order is referred to as the solution of the equation of motion of the density matrix when only the resonant field is applied. -- We obtain a set of equations in second order of the density matrix element p₁₀⑵ (ω) from which the gain function can be derived. This set of equations in the special case of steady state is accidentally similar to those obtained by Mollow in his study of the power spectrum of a strong driven two-level system. We have shown that the SRS in the steady state under the resonant field interaction, is drastically reduced in general. When the flopping frequency is larger than the relaxation constants (Ω > r), we find there appears both weak positive and weak negative gains on both sides of the ordinary SRS components. Since we retain our second-order equations in a general form rather than the form for steady state, we are able to take account of the dependence on the transient zeroth solution. By employing the Laplace transform technique with the help of convolution products, we are able to solve for ρ₁₀⑵(ω) in the stationary flopping state. When the intensity of the resonant field is high, we have found theoretically that both the Stokes and anti-Stokes component become doublets and equally displaced by the amount of the flopping frequency, Ω, on the opposite sides of ordinary Stokes and anti-Stokes components, respectively. The gain maxima are approximately the order of Ω/4r times the ordinary gain of the Stokes component, where Ω/r >> 1 if the flopping exists. The gains are therefore large in comparison with the ordinary gain for SRS in the steady state.

Jan 1, 19780 citations