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 waveguide's 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.
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 waveguide's exit is determined by the
number of the spatial modes of pump radiation and the amplification of the Stokes radiation throughout the waveguide's
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.
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 waveguide's 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.
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 waveguide's exit is determined by the
number of the spatial modes of pump radiation and the amplification of the Stokes radiation throughout the waveguide's
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
There has been offered a method oftransformation of spatial coherency of pulse laser
radiation based on the phase self-modulation in multi-mode waveguide. We have conducted
analysis of the peculiarities of the transfer of correlation properties of the radiation in
gradient waveguide with regular and non-regular core's refraction index profile distribution.
We have also conducted a comparative analysis of the global coherency degree parameter of
the radiation at the end of non-homogeneous waveguide and non-waveguide media. We
show that the most effective mechanism of decorrelation of pulse radiation in the waveguide
is the fluctuations of radiation phase scattered on the heterogeneousness of the waveguide's
core refraction index; the fluctuations being induced at non-linear interaction of the radiation
with spatially non-uniform intensity distribution.
Theoretical and experimental analysis of two schemes for controllable transformation of short laser pulses coherence is presented: self phase-modulation in CCl4 with thermal nonlinearity and time-delay line. Such methods can be utilized in high-speed schemes of speckle-noise reduction for perspective systems or laser UV projective lithography.
The paper deals with aberrations, introduced by imperfect optical components to adaptive system, which is aimed to reduce a refraction caused divergence of collimated signal beam, sent from underwater. An estimation of their effect is carried out by the example of the most severe of them - due to finite resolution of an adaptive element. By this way limits of the scheme applicability are found out.
A comparative analysis of effectiveness of two adaptive algorithms is carried out using the formalism of radiation transfer theory. It is shown that under practically reasonable conditions the method with pure amplitude adaptation provides better results both on energetic and far field angular parameters of the scheme than that based on phase conjugation. The consideration is illustrated with a simple model situation.
An adaptive system for divergence reduction of optical radiation passing through a waved interface of two different media has been investigated. The proposed approach provides one- way transfer of signal. The effectiveness of the method has been experimentally confirmed.
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