OPTICAL SIGNAL PROCCESSING WITH PHOTOREFRACTIVE MATERIALS

Abstract

CURRENT ADVANCES IN INFORMATION TECHNOLOGIES HAVE STIMULATED A PROGRESSIVE INTERACTION BETWEEN "OPTICS" AND "INFORMATION". IN THIS CONTEXT, NON-LINEAR OPTICSAND HOLOGRAPHY CONSTITUTE ALTERNATIVE SOLUTIONS, THAT ESTABLISH NEW FRONTIERS. THE DEVELOPMENT OF NEW DYNAMIC HOLOGRAPHIC RECORDERS, COUPLED WITH THE UNDERSTANDING OF THEIR FUNDAMENTAL INTERACTION WITH LIGHT, LEAD TO NOVEL INFORMATION STORAGE AND PROCESSING METHODS. THE PRESENT STUDY FOCUSES ON THE ABOVE ISSUES. A PHOTOREFRACTIVE BARTIUM TITANATE BASED SYSTEM CAPABLE OF PERFORMING COHERENT PULSED AMPLIFICATION OF A WEEK CONTINUOUS WAVE SIGNL IS DEMOSTRATED. THE VERY LARGE NET AMPLIFICATION GAIN ATTAINED BY THIS SYSTEM IMPLIES GREAT PROSPECTS IN LOW LIGHT LEVEL CINEHOLOGRAPHY. A PHOTOREFRACTIVE ADAPTIVE TRANSMISSION SYSTEM BASED ON THE COMBINED ACTION OF A PHOTOREFRACTIVE STRONTIUM BARRIUM NIOBATE AMPLIFIER AND A SELF-PUMPED BARIUM TITANATE PHARE CONJUGATOR IS PRESENTED. THIS SYSTEM IS CAPABLE OF PRODUCING AN AMPLIFIED REAL-TIME PHASE CONJUGATE REPLICA OF A WEEK SIGNAL BEAM AND SIMULTANEOUSLY INTERCHANGING HIGH FREQUENCY INFORMATION BETWEEN BEAMS BY UTILIZING THE DYNAMIC GRATING INERTIA. A MULTI-BEAM CONFIGURATION WHICH ESTABLISHES AN ADAPTIVE LINKING SCHEME BETWEEN DIFFERENT INFORMATION CHANNELS IS DISCUSSED HERE. BIPOLAR PHOTOREFRACTION IN PHOTOREFRACTIVE BISMUTH SILICATE IN THE NEAR INFRARED (780 NM) IS OBSERVED. THE DYNAMIC BEHAVIOR OF THIS PHENOMENON IS STUDIED BOTH EXPERIMENTALLY AND THEORETICALLY AND A METHOD FOR THE DETERMINATIONOF IMPORTANT MATERIALS PARAMETERS(ABSTRACT TRUNCA