Topic
Organic photorefractive materials
About: Organic photorefractive materials is a research topic. Over the lifetime, 697 publications have been published within this topic receiving 13041 citations.
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16 Jul 2002
TL;DR: In this paper, an external voltage is applied to the converter body to accelerate the buildup of changes in the refractive index caused by an increase in the charge carrier mobility or charge carrier density.
Abstract: A method of and/or device for writing to an optical modulator using electromagnetic write beams, the modulator having a photorefractive converter body in which the space-modulated write beam may induce changes in the refractive index. An external voltage may be applied to the converter body. The intensity of the external voltage may be selected within a voltage range in which the buildup of changes in the refractive index may be accelerated by an increase in the charge carrier mobility or charge carrier density.
14 Jul 1997
TL;DR: In this article, the performance of a synchronously-pumped optical parametric oscillation (SPOPO) with a tunable mode-locked Ti:sapphire laser was described.
Abstract: Periodically-poled lithium niobate (PPLN) offers a number of major advantages for optical parametric oscillators (OPOs). These include the large nonlinearity (d 20 pm/V) and the ability to phase-match non-critically for any wavelengths in its broad transmission range. These features provide the possibility of single-resonant oscillation at threshold powers compatible with those available from cw pump lasers. In the case of synchronously-pumped optical parametric oscillation (SPOPO) threshold can be reached with a significantly lower average pump power, since the parametric gain is determined by the peak power. For example, a SPOPO based on LBO has shown a threshold pump power (average) of -70 mW.’ Material dispersion becomes an important consideration in the context of short pulse operation (picoseconds or less) as involved in synchronously-pumped OPOs. Lithium niobate has a significantly larger dispersion than LBO, thus imposing a more stringent restriction on crystal length than is the case for LBO. Nevertheless, the much larger nonlinearity of PPLN more than compensates for this length restriction, so that in practice PPLN proves to be a very attractive material for a SPOPO. In this paper we describe the performance of SPOPOs based on PPLN pumped by a modelocked Nd:YLF laser (1.047 pm)2 and by a tunable mode-locked Ti:sapphire laser, both operating in the picosecond regime. The 1.047 pm pumped PPLN device shows clear advantages over devices based on LBO. A notable advantage is the ability to achieve phase-matching for direct pumping with the fundamental wavelength of the Nd:YLF laser, whereas in the case of LBO phase-matching requirements made it necessary to pump with the second harmonic of the Nd:YLF laser, thus involving added complexity. Secondly, the PPLN device offers tunability to longer wavelengths, beyond 4 pm, compared with LBO where the IR absorption edge limits operation to -2.6 +m in the case of LBO. Thirdly, very low thresholds of -7.5 mW average pump power have been achieved for a 20 mm long PPLN device, around an order of magnitude lower than the best results obtained with LBO. Similar low thresholds have also been obtained with a Ti:sapphire-pumped SPOPO, using a somewhat shorter PPLN crystal (mm) on account of the increased dispersion for the shorter (-0.8 km) pump wavelength. High slope efficiencies are achieved (>40%) with both devices. A detailed discussion of the operating characteristics of these SPOPO devices will be given, with indications of how further improvements might be made.
19 Jul 2005
Abstract: In a planar aligned photorefractive liquid crystal light valve we show the appearance of optical structures induced by a single mirror feedback. We report the typical responses of the valve as a function of the pump intensity. We observe that the length scale of the structures scales with the light free propagation length, according with a diffractive feedback model.
08 Dec 2003
TL;DR: In this article, the photorefractive effect of 14 ferroelectric liquid crystals (FLCs) mixed with a photoconductive compound was investigated by two-beam coupling experiments.
Abstract: The photorefractive effect of 14 ferroelectric liquid crystals (FLCs) mixed with a photoconductive compound was investigated by two-beam coupling experiments. The influence of the properties of low-molecular-weight FLCs on the photorefractive iffect was examined, and it was found that the photorefractive two-beam coupling gain coefficients and the refractive index grating formation time are strongly dependent on the properties of FLCs. The effects of the magnitude of the spontaneous polarization, viscosity, and the homogeneity of the surface-stabilized state on the photorefractivities of FLCs are discussed based on these findings.
06 Jun 1990
TL;DR: In this paper, the optical phase-conjugate wave from two sets of refractive index gratings with large and small periods formed in photorefractive and optically active Bi/sub 12/SiO/sub 20/ were successfully discriminated by the newly developed interference method, which takes advantage of the finite coherence length of Ar ion lasers.
Abstract: The optical phase-conjugate waves from two sets of refractive index gratings with large and small periods formed in photorefractive and optically active Bi/sub 12/SiO/sub 20/ were successfully discriminated by the newly developed interference method, which takes advantage of the finite coherence length of Ar ion lasers. The method was applied to the investigation of the external electric-field dependence of the optical phase-conjugate waves from the both sets of gratings. >