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Nonlinear Optics/Laser Matter Interaction
Nonlinear Optical Phenomena
Regrettably, our high
profile work on spatial solitons in Rubidium vapour was discontinued
following the departure of Dr Tikhonenko early in the year. In
collaboration with members of the Optical Sciences Centre we have,
however, continued to study phenomena associated with the excitation
and behaviour of optical vortex solitons in finite beams while most
of the experimental work has concentrated on the excitation and
interaction of spatial solitons in photorefractive media. Some work
has continued on short pulse synchronously pumped optical parametric
oscillators. In particular the inclusion of group velocity dispersion
compensation within the OPO resonator has allowed pulses close to the
transform limit to be obtained.
Photorefractive Spatial
Solitons
W. Krolikowski
In the experiments with
strontium barium niobate crystals, we demonstrated for the first
time, the anisotropic nature of spatial soliton interaction. We
showed, contrary to the common belief that incoherent solitons always
attract, that the interaction is much more complicated and that
solitons may actually attract or repel depending on their mutual
location. This has profound consequences for soliton dynamics and may
result in mutual rotation or oscillation of solitons. The
experimental results are in excellent agreement with numerical
simulations.
We also investigated
experimentally the mutual interaction of multiple solitons. We
demonstrated experimentally, that solitons can mutually annihilate
when interacting coherently in photorefractive crystals and this
process is governed by mutual phase relations.
Coherence effects
in photorefractive interaction
We investigated
theoretically, the phase conjugation process in photorefractive
crystals with partially coherent optical beams. We found exact
analytical solutions to the corresponding evolution equations and
showed how partial coherence affects phase conjugate
reflectivity.
Nonlinear Optics /Laser Matter
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Date last modified: Fri, 20 Feb 1998