Abstract
The photo-electromotive force (photo-emf) generated by a vibrating laser speckle pattern at 1064 nm in the bulk of a photorefractive vanadium-doped CdTe crystal is used to evaluate the sample's response time and the vibration amplitude of the speckle pattern. We measured the first harmonic temporal term of the photocurrent, under different conditions, as a function of the vibration amplitude, vibration frequency, and irradiance, in order to verify some features of the theoretical model for large vibration amplitude speckle photo-emf. The most interesting feature is the presence, for sufficiently fast vibrations, of a maximum in this first harmonic term at a fixed vibration amplitude-to-speckle size ratio whose position should depend only on the dark conductivity to photoconductivity ratio. The presence of such a maximum is experimentally confirmed and opens the way for rather simple calibration of the setup in practical applications. We also demonstrate the application of this photo-emf signal to evaluate the material response time of the CdTe:V crystal.
Published Version
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