Anatoly I. Kitsak

The efficiency of the non-stationary process of the transformation of the spatial coherence of the pulse laser radiation in the multimode waveguide at the phase self-modulation

We conduct a theoretical analysis of two models of transformation the spatial coherency transformation of the radiation propagating in the multi-mode waveguide. For each of them we obtain analytical relations connecting the number of spatially-coherent modes of the radiation appearing in the waveguide, parameters of the incoming radiation and the characteristics of the waveguide. We assess the efficiency of the radiation de correlation at various initial spatial statistics of the radiation and its quasi-nonstationary non-linear interaction with the waveguides core. We find that the main factor limiting the de-correlation level of the light beams in the multi-mode waveguide with quartz core is the excitation of the Raman scattering. Raman scattering decreases the effective intensity of the radiation at the original frequency and the changes the dynamics of the phase-amplitude transformation of light.

Studies of the Angular Frequency Spectrum Raman Scattering Stokes Component Radiation Excited in an Extensive Multimode Waveguide

We conduct a theoretical analysis of the Stokes component mode structure of the Raman scattering. The Raman scattering is excited in a multimode waveguide with pump radiation having statistics corresponding to the model of the narrow-band Gaussian noise. We obtain an analytical relation connecting the number of spatially coherent modes of the Stokes component, characteristics of the waveguide and conditions of the Raman scattering excitation. It follows from the obtained relation that the Raman scattering spatial coherency degree at the waveguides exit is determined by the number of the spatial modes of pump radiation and the amplification of the Stokes radiation throughout the waveguides length. There exists a threshold in the amplification corresponding to the unlimited increase of the number of the spatially coherent modes of the Raman scattering and therefore to a zero of spatial coherency. Conducted estimations show that at the Raman scattering threshold value of the radiation intensity the number of the spatially coherent modes of the Raman scattering Stokes component should be comparable to that of the thermal source. Experimentally, measured dispersion of the spatial intensity fluctuations of the Stokes component isolated with an interference filter (spectral bandwidth ~ 1nm, λ = 620nm) is three time smaller than that of the luminescent lamp radiation.

The efficiency of the spatial coherency nonlinear transformation of the pulse laser radiation in a multimode waveguide at different statistical models of the incoming radiation

We conduct a theoretical analysis of two models of transformation the spatial coherency transformation of the radiation propagating in the multi-mode waveguide. For each of them we obtain analytical relations connecting the number of spatially-coherent modes of the radiation appearing in the waveguide, parameters of the incoming radiation and the characteristics of the waveguide. We assess the efficiency of the radiation de correlation at various initial spatial statistics of the radiation and its quasi-nonstationary non-linear interaction with the waveguides core. We find that the main factor limiting the de-correlation level of the light beams in the multi-mode waveguide with quartz core is the excitation of the Raman scattering. Raman scattering decreases the effective intensity of the radiation at the original frequency and the changes the dynamics of the phase-amplitude transformation of light.

Analysis of spatial modes of the Raman scattering stokes component radiation excited in an extensive multimode waveguide.

We conduct a theoretical analysis of the Stokes component mode structure of the Raman scattering. The Raman scattering is excited in a multimode waveguide with pump radiation having statistics corresponding to the model of the narrow-band Gaussian noise. We obtain an analytical relation connecting the number of spatially coherent modes of the Stokes component, characteristics of the waveguide and conditions of the Raman scattering excitation. It follows from the obtained relation that the Raman scattering spatial coherency degree at the waveguides exit is determined by the number of the spatial modes of pump radiation and the amplification of the Stokes radiation throughout the waveguides length. There exists a threshold in the amplification corresponding to the unlimited increase of the number of the spatially coherent modes of the Raman scattering and therefore to a zero of spatial coherency. Conducted estimations show that at the Raman scattering threshold value of the radiation intensity the number of the spatially coherent modes of the Raman scattering Stokes component should be comparable to that of the thermal source. Experimentally, measured dispersion of the spatial intensity fluctuations of the Stokes component isolated with an interference filter (spectral bandwidth ~ 1nm, λ = 620nm) is three time smaller than that of the luminescent lamp radiation