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The object of research is a mathematical model of the photoelastic interaction in an acousto-optic delay line (AODL). Two possible cases are discussed as applied to the ratio of the input pulse duration to the time of crossing the optical beam by an elastic wave packet. It is shown that in both cases the voltage at the output of the device is found as the sum of three components, which are formed by different mechanisms. If the duration of the input pulse is longer than the time of crossing the optical beam by an elastic wave packet, then the first component is determined by the process of entry of the leading edge of the elastic wave packet into the optical beam, the second – by the process of complete interaction of the optical beam with the elastic wave packet, and the third – by the process of exit of the trailing edge of the elastic wave packet from the optical beam. In the second case, i. e. when the duration of the input pulse is less than the time of crossing the optical beam by an elastic wave packet, the first term is determined by the process of entry of the elastic wave packet into the optical beam, the second – by the process of advancing the elastic wave packet in the aperture of the optical beam, and the third – by the process of exit of the elastic wave packet from the aperture of the optical beam. The corresponding equations for calculating the parameters of the output pulse were obtained by applying a rectangular pulse to the AODL input. It is proved that if the pulse duration at the AODL input is longer than the time of intersection of the optical beam by an elastic wave packet, then the pulse duration at its output will be equal to the duration of the input pulse. In the case when the duration of the input pulse is less than the time of crossing the optical beam by an elastic wave packet, the duration of the output pulse will be determined by the time of propagation of the elastic wave packet in the aperture of the optical beam. The obtained equations are confirmed by numerical calculations. The results of the numerical analysis were tested experimentally, which confirms the unequivocal adequacy of the proposed model of photoelastic interaction in an AODL.

The paper emphasizes that intensive utilization of the optical range increases the need for the development of new optoelectronic devices. Accordingly, there is a growth in the need for effective methods and tools to study photoelectric properties of semiconductor materials, including photo-detectors.In the paper we have analyzed the well-known methods and tools for measuring the photo-detector parameters, defined the restrictions in their applications, and proved that it is relevant to create a measuring system, the parameters of which are easily adapted to the study of photoelectric characteristics of a wide range of semiconductor materials, including photo-detectors.The scheme and principle of operation of the acousto-optic processor and the features of the photo-elastic effect are discussed, and it is proved that they can be used to form a light pulse of required duration and power. The expressions obtained for calculating the response at the acousto-optic processor output enable us to estimate separately the effects of time of crossing the optical beam by the elastic wave packet and the photo-detector inertia.The capability to determine the time of crossing the optical beam by the elastic wave packet and taking it into account as a device error has been substantiated. The proposed formulas have been tested and by numerical analysis based on the datasheet specifications of the FD-24K photodiode, the effectiveness of the obtained expressions has been convincingly proven.The inertia parameters of a particular sample of the FD-24K photodiode are experimentally studied. The emphasis is upon measuring the rise time of the transient response of the object under study. The exact rise time value of the transient response of the experimental FD-24K sample was approximately 7 μs, which is less than that indicated (≤10 μs) in the product certificate. In real life, such a measurement is necessary when selecting the photodiode pairs with identical parameters.By comparing the results of numerical analysis and experimental studies, it has been convincingly proven that the features of the photo-elastic effect can be used to construct a light pulse shaper with the required parameters.