The external small signal amplification ability of the Bragg acoustooptical bistable system has been studied in this paper.The small signal amplification in modulation effect as reference([9]) predicted has not been observed in the stability region in our experiment.
Over the past decade, research with acoustooptic hybrid bistable devices has been primarily concerned with operation in the first Bragg regime involving two to four diffracted orders. In this paper, a model that includes both acoustooptic diffraction and nonlinear feedback will be used to investigate optical bistability in the second Bragg regime. In addition, theoretical simulations will be used to compare this system with an identical system operating in the first Bragg regime. Theoretical and experimental results will be presented.
We report the observation of optical stability for a plane parallel semiconductor crystal which forms a Fabry-Perot interferometer using only the natural reflectivity of its surfaces. Nonlinear transmission is observed for cw laser intensities above ∼ 100 W/cm2 for radiation at 1895 cm−1 near the energy gap of InSb at 5 K. The effect is interpreted in terms of a very large intensity-dependent refractive index giving a 5λ/2 optical thickness change for an intensity of ∼2 kW/cm2. Clear bistability is seen in fifth-order interference, the first such observation above first order in an intrinsic, one-element system, in addition to regions exhibiting signal amplification. The same crystal also shows strong modulation of the transmission of one laser beam induced by a second, with real signal gain, thus demonstrating an ’’optical transistor.’’