@Workshop{Supelec414,
author = {Delphine Wolfersberger},
title = {{Control of visible or near infrared light in bulk photorefractive materials: from waveguides to cavities}},
year = {2008},
booktitle = {{Kick-off Workshop of the Action MP0702}},
month = {apr},
address = {Warsaw (Poland)},
url = {http://cost-mp0702.nit.eu/cost-mp0702/events/warsaw-worshop/contribution/Abstracts-3.2},
abstract = {The development of all-optical devices operating entirely with
light promises significant advances in communication
technologies. Control of light by light can be realised in
nonlinear materials with optical properties dependent on light
intensity. For example, the self-action of beams can result in
suppression of diffraction spreading and formation of spatial
solitons. Interacting solitons co or counter-propagating can
enable passive or active optical components such as optical
routers, reconfigurable interconnects and perform all-optical
computations.
The dynamic creation of waveguides in photorefractive
semiconductors (InP:Fe, Sn2P2S6) is investigated in the case of a
longitudinal soliton-like propagation of a self-focused
near-infrared wave. The corresponding response time of the
self-focused waveguide is of the order of tens of microseconds at
telecommunications intensities. Systematic measurements of the
fast photorefractive self focusing as a function of the beam
intensity, the electric field applied and the temperature show
two different characteristic time scales : one around the tens of
µs related to the transient regime and one of the order of
several ms related to the steady state regime. A theoretical
model simulating the temporal dynamic of the self focusing is
developed and checked against experimental results. In the case
of an exact balance between the diffraction and the nonlinear
optical effect, the beam propagates as a spatial soliton and by
interactions, simple or more complex optical functions as X or Y
couplers can be realized. An other interesting application
concern the self-alignment between a laser diode and an optical
fiber by using counter-propagating solitons interactions. In such
a case or for a photorefractive material in a laser cavity, the
control of spatio-temporal instabilities is of practical interest.}
}