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Near infrared steady state photorefractive self focusing in Sn2P2S6:Te crystals

Tin hypothiodiphosphate (SPS) is a wide band gap semiconductor ferroelectric that has interesting properties for photorefractive (PR) applications such as high two wave mixing gains, large transparency window coupled with a fast response time and a large electro-optic coefficient. Taking into account all SPS characteristics, its behavior is investigated with respect to photorefractive self focusing in the near IR in the aim of identifying its potential for the creation of self induced optical waveguides. The performed experiments show that the steady state is reached faster than the exposure time of the CCD camera used.

Nicolas Fressengeas

@fresseng 11 yr. ago

Near infrared steady state photorefractive self focusing in Sn2P2S6: Te crystals

Nicolas Fressengeas

@fresseng 11 yr. ago

Fast photorefractive self focusing in InP : Fe in near infrared

Nicolas Fressengeas

@fresseng 11 yr. ago

Roles of resonance and dark irradiance for infrared photorefractive self-focusing and solitons in bi-polar InP:Fe

This paper shows experimental evidence of photorefractive steady state self-focusing in InP:Fe for a wide range of intensities, at both 1.06 and 1.55µm. To explain those results, it is shown that despite the bi-polar nature of InP:Fe where one photocarrier and one thermal carrier are to be considered, the long standing one photocarrier model for photorefractive solitons can be usefully applied. The relationship between the dark irradiance stemming out of this model and the known resonance intensity is then discussed.

Nicolas Fressengeas

@fresseng 11 yr. ago

Fast Self-Focusing of Light in a Photorefractive Semiconductor for Reconfigurable Optical Communications

We theoretically and experimentally report on fast self-focusing of light in a photorefractive semiconductor. In these applications, semiconductor materials are very attractive considering their high sensitivity at telecommunication wavelengths (1.55 .m), short response time and memory effect. Photorefractive self-focusing and soliton interactions lead to self-induced and reconfigurable semiconductor waveguide which would find interesting applications in optical communications, optical routing or interconnexions.

Nicolas Fressengeas

@fresseng 11 yr. ago

Temporal Behavior of Photorefractive Self-Focusing in InP:Fe Crystals at Infrared Wavelengths

Temporal and spatial dependency of photorefractive self focusing in InP:Fe from intensity and temperature is compared to a theoretical model; self focusing and bending occur on a microseconds timescale for low beam intensities.

Nicolas Fressengeas

@fresseng 11 yr. ago

Near infrared photorefractive self focusing in Sn2P2S6:Te crystals

The experimental observation of photorefractive self focusing in Sn2P2S6 : Te bulk crystals at 1.06 mm wavelength is presented. Steady state self focusing is reached as fast as 15 ms for an input peak intensity equal to 160 W/cm2. Self focusing is maximum for input peak intensities around 15 W/cm2 and is decreasing for intensities below and above this value.

Nicolas Fressengeas

@fresseng 11 yr. ago

Fast photorefractive self-focusing in InP:Fe semiconductor at infrared wavelengths

Photorefractive beam self-trapping is investigated in InP:Fe and is shown to occur within tens of microseconds after beam switch on. This fast response time is predicted by an analytical theoretical interpretation based on a simple photorefraction model which suggests buildups in a time range consistent with experiments.

Nicolas Fressengeas

@fresseng 11 yr. ago

Real-time Photoinduced Waveguides in Sn2P2S6 Bulk Crystals with Visible or Near Infrared Light

Light induced waveguides are demonstrated in Sn2P2S6by two alternative methods allowing a waveguide formation time of the order of 1 ms. The techniques are based on shaped visible lateral illumination and near infrared self-focusing.

Nicolas Fressengeas

@fresseng 11 yr. ago

Light deflection and modulation through dynamic evolution of photoinduced waveguides

Light induced waveguides produced by lateral illumination of a photorefractive crystal show a complex dynamic evolution upon removal of the sustaining applied electric field. Using this effect, deflection and modulation of the guided light is realized by taking advantage of the screening and counter-screening of the space charge distribution. The spot separation upon deflection can exceed 10 times the original waveguide width. Numerical simulations of the refractive index evolution and beam propagation show a good agreement with the observations.

Nicolas Fressengeas

@fresseng 11 yr. ago

Control of visible or near infrared light in bulk photorefractive materials : from waveguides to cavities

Nicolas Fressengeas

@fresseng 11 yr. ago

Fast photorefractive self focusing in InP:Fe semiconductor at near infrared wavelengths

Self-trapping of optical beams in photorefractive (PR) materials at telecommunications wavelengths has been studied at steady state in insulators such as SBN [1] and in semiconductor InP:Fe [2], CdTe [3]. PR self-focusing and soliton interactions in semiconductors find interesting applications in optical communications such as optical routing and interconnections because of several advantages over insulators: their sensitivity to near-infrared wavelengths and shorter response time. Photorefractive self focusing in InP:Fe is characterized as a function of beam intensity and temperature. Transient self focusing is found to occur on two time scales for input intensities of tens of W/cm2 (one on the order of tens of µs, one on the order of milliseconds). A theory developed describes the photorefractive self focusing in InP:Fe and confirmed by steady state and transient regime measurements. PR associated phenomena (bending and self focusing) are taking place in InP:Fe as fast as a µs for intensities on the order of 10W/cm2 at 1.06 µm. Currently we are conducting more experiments in order to estimate the self focusing response time at 1.55µm, to clarify the temporal dynamic of the self focusing and to build up a demonstrator of fast optical routing by photorefractive spatial solitons interactions.

Nicolas Fressengeas

@fresseng 11 yr. ago

Guides d'ondes photoinduits dans des fibres cristallines LiNbO3

Nicolas Fressengeas

@fresseng 11 yr. ago

Reconfigurable one and two dimensional waveguides in strontium barium niobate induced by lateral illumination

Nicolas Fressengeas

@fresseng 11 yr. ago

One and two-dimensional reconfigurable light induced waveguides and their dynamics

Nicolas Fressengeas

@fresseng 11 yr. ago

Control of the formation of near infrared photoinduced waveguides in photorefractive semiconductors

Nicolas Fressengeas

@fresseng 11 yr. ago

Numerical analysis of beam self-focusing in photorefractive InP:Fe

Nicolas Fressengeas

@fresseng 11 yr. ago

Optically induced waveguide in iron-doped LiNbO3 crystal fibers

Nicolas Fressengeas

@fresseng 11 yr. ago

Micro-pulling-down growth and optical waveguide engraving in Fe-doped LiNbO3 single crystal fibers

Nicolas Fressengeas

@fresseng 11 yr. ago

Optical waveguide engraving in a LiNbO3 crystal fiber

This paper reports the engraving of an optical waveguide inside a LiNbO3 crystal fiber via the photorefractive effect and an optical vortex. Afterwards this waveguide was successfully tested and its properties evidenced.