This paper is devoted to growth and doping of semiconductor photorefractive cadmium telluride (CdTe) crystals as well as to the investigation into their spectroscopic and non-linear optical properties. The crystals are doped with vanadium, iron, and titanium. Two methods have been used for the production of doped crystals: diffused post-growth doping and growth of doped crystals from melt. Non-linear optical properties of the samples were studied at a wavelength of 1.06 μm for a four-wave mixing geometry and 1.54 μm for a two beam coupling. Maximum 2% diffraction efficiency at 1.06 μm was revealed with the convergence angle of light beams approximating 8" for the grating period of 7 μm. In this case the dynamic grating lifetime was found to be about 0.2 μs. Under beam coupling at ~ 1.5 μm, the conditions of maximum gain (0.7 cm-1) were observed in the experiment for a minimum grating period of 1 μm; and the gain could be slightly enhanced by application of a dc electric field (~ 2 kV/cm) up to 40%.
The paper is a study into the spectroscopic and nonlinear-optical properties of semiconductor photorefractive crystals based on cadmium telluride (CdTe) doped with transition metals or irradiated by electrons and gamma-quanta. The protorefractive response is analyzed using the four-wave mixing pattern of laser pulses one of which is delayed in time. It is found that both irradiation and doping of cadmium telluride crystals with vanadium, titanium or iron leads to
changes in the spectroscopic and nonlinear-optical properties of the crystals. Apart from relatively narrow (about 100 nm ) bands appearing in the absorption spectra due to additional energy levels within the band gap, one can observe variations in the absorption factor over a wide spectral region ( 1-3 μm). Recording of dynamic holograms is realized with no external electric field owing to pulsed laser radiation at a wavelength of 1.06 μm and diffraction efficiency of 1-2%. Continuous laser excitation (1.5 μm wavelength and an applied external electric field of about 2 kV /cm ) with the use of the two-wave mixing pattern has enabled energy transfer to a weak wave giving the amplification factor that
comes to 1 cm-1.
In this paper we propose a new method to control the spectroscopic and nonlinear-optical properties of photorefractive semiconductor CdTe crystals using the radiation defects caused by electrons and gamma-quanta irradiation. The photorefractive response is analyzed using the four-wave mixing pattern of laser pulses, one of which is delayed in time. It is found that both the irradiation and doping of cadmium telluride crystals with vanadium, titanium or ferrum leads to changes in the spectroscopic and nonlinear-optical properties of the crystals. Apart from relatively narrow bands appearing in the absorption spectra due to additional energy levels within the band gap, one can observe variations in the absorption factor over a wide spectral region. Recording of dynamic holograms is realized with no external electric field owing to pulsed laser radiation at a wavelength of 1.06 μm and diffraction efficiency of 1 - 2 %.
In the work consideration was given to investigation into the spectroscopic and nonlinear optical properties of photorefractive semiconductor cadmium telluride crystals doped with vanadium, ferrum and titanium. Introduction of dopants was required to produce an impurity absorption band in the near IR region and enhance the photorefractive properties. Two methods have been used for the production of doped crystals: diffused post-growth doping and growth of doped crystals from melt. Nonlinear optical properties of samples were studied at the wavelength of 1.06 micrometer in a four-wave mixing scheme. Maximum diffraction efficiency was revealed for the convergence angle of light beams approximating 8 degree, with the grating period of 7 micrometer and was equal to 2%. The dynamic grating lifetime was about 0.2 microseconds.
A scheme for the realization of optical bistability in a nonlinear Fabry-Perot (F-P) interferometer has been considered under conditions of multifrequency excitation. The dependencies of the spectral-components intensities, their ratios, and the total intensity at F-P output on the input intensity have been analyzed. The possibility to realize the optical control of radiation color as perceived by the eye has been shown.
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