Foreign Collaborators

Dr. W.N.Lawless, Ceramphysics Inc., Westerwille, Ohio, USA

Dr. M. Weihnacht, Institute of Solid State and Materials Research, Dresden, Germany

Dr. J.C. de Miscault, Laserdot (Group Aerospatiale), Marcousis, France

№ -0137 Vibration Analysis Using a New Type of Adaptive Photo-Detector

Full Title:	Vibration Analysis Using a New Type of Adaptive Photo-Detector Based on the Effect of the Non-Steady-State Photo-Electromotive Force
Technology Field(s):	INF-SIG: Information and Communications / Sensors and Signal Processing MAT-CER: Materials / Ceramics INS-DET: Instrumentation / Detection Devices CHE-RAD: Chemistry / Photo and Radiation Chemistry

Contributors

Igor A Sokolov

A.F.Ioffe Physico-Technical Institute (Ioffe Inst) 26, Polytechnicheskaya str., St Petersburg, 194021, Russia Phone: 7+812+5159193; 7+812+2473973 Fax: 7+812+5156747; 7+812+2475416 isok@math.ipme.ru

Present Status of Research

Brief Description of Research

A new type of adaptive photodetector has been developed based upon the effect of a non-steady-state photoelectromotive force. The main goal of this photodetector is the direct conversion of a phase-modulated optical signal into the electrical current, with the concomitant suppression of slowly varying phase shifts in the interferometer arms due to temperature variations, vibrations, etc. Laser vibrometers and sensors based on this effect have the same sensitivity as conventional interferometric systems, however, they are more simple, reliable and cost effective. Adaptive photodetectors could find various applications such as materials inspection, calibration of actuators and transducers, measurements of piezoelectric and electrooptic coefficients of thin films (utilization in microelectromechanic systems (MEMs)) and optical detection of ultrasound.

The effect of the non-steady-state photoelectromotive force is a powerful tool for the semiconductor material parameters investigation. The type of photoconductivity could be determined, as well the average diffusion and drift length of photocarriers, their mobility and lifetime. This effect was applied for characterization of GaAs, InP, Bi₁₂SiO₂₀, KNbO₃, BaTiO₃ and even amorphous silicon.

Legal Aspects

Patent application for the material characterization has been approved in Russia. However, there are no patent applications for the laser sensor systems.

Special Facilities None.

Scientific Papers

I.A.Sokolov, and s.I.Stepanov, “Non-steady photovoltage in crystals with long relaxation time of photoconductivity,” Electron.Lett., V.26, pp. 1275-1277 (1990).

M. P. Petrov, I. A. Sokolov, S. I. Stepanov, and G. S. Trofimov, “Non-steady-state photoelectromotive force induced by dynamic gratings in partially compensated photoconductors,” J.Appl.Phys., v. 68, pp. 2216-2225 (1990).

S.I. Stepanov, I.A. Sokolov, G.S. Trofimov, V.I. Vlad, D. Popa I. Apostol, “Measuring vibrarion amplitudes in the picometer range using moving light gratings in photoconductive GaAs:Cr,” Opt.Lett. v.15, pp. 1239-1241 (1990).

S.I. Stepanov, I.A. Sokolov, G.S. Trofimov (invited), “Adaptive photodetectors using photorefractive crystals and the effect of the non-steady-state photo-EMF,” Conference on Lasers and Electrooptics (CLEO’91), Baltimore, Maryland, USA, v.10, pp. 326-328 (1991).

I.A. Sokolov, S.I. Stepanov, G.S. Trofimov, “Measurement of small vibration amplitudes of the diffuse objects using adaptive GaAs:Cr photodetectors,” Sov. Phys.-Acoust., v.37, No.5, pp. 519-521 (1991).

I.A. Sokolov, S.I. Stepanov, G.S. Trofimov, “Holographic currents and the non-steady-state photoelectromotive force in cubic photorefractive crystals,” J.Opt.Soc.Am. B., v. 9, pp. 173-176 (1992).

I.A. Sokolov, S.I. Stepanov, “Non-steady-state photo-electromotive force in crystals with long photocarrier lifetimes,” JOSA B, v.10, pp. 1483-1488 (1993).

I.A. Sokolov, V.V. Khorenko, S.I. Stepanov, “Monitoring bending motion amplitudes of piezoceramic plates using adaptive photodetectors GaAs:Cr,” Ferroelectrics, v.160, pp. 317-322 (1994).