COHERENCE HOLOGRAPHIC REFLECTOR BASED ON NON-LINEAR MATERIALS

THE INCREASING APPLICATION OF LASERS IN FREE-SPACE AND GUIDED WAVE COMMUNICATION AS WELL AS REMOTE SENSING HAS CREATED A NEED FOR MEANS TO DETECT LASER SIGNALS EFFECTIVELY WITH THE DESIRED SIGNAL-TO-NOISE RATIO IN THE PRESENCE OF STRONG AMBIENT LIGHT. FOR THIS PROPOSED RESEARCH, POC HAS DEVISED A FUNDAMENTALLY DIFFERENT APPROACH TO DISCRIMINATING LASER SIGNALS FROM AMBIENT BACKGROUND BY TAKING INTO ACCOUNT THE DEGREE OF COHERENCE OF THE INCIDENT LASER SIGNAL BESIDES ITS WELL-DEFINED WAVELENGTHS AND LINEWIDTHS. IN THIS CONCEPT, A SPECIAL COHERENCE HOLOGRAPHIC REFLECTING FILTER WILL BE FABRICATED THAT CAN DISCRIMINATE BETWEEN LIGHT SIGNALS OF DIFFERENT COHERENCE. THE NOVEL COHERENCE DISCRIMINATING REFLECTION (CDR) FILTERS FROM THIS RESEARCH ALSO REPRESENT A NEW CLASS OF HOLOGRAPHIC ELEMENTS FABRICATED USING PHOTOREFRACTIVE CRYSTALS (LITHIUM NIOBATE). IN ADDITION TO ENABLING MORE EFFECTIVE LASER DETECTION, THE CONCEPT IN THIS RESEARCH CAN ALSO LEAD TO A NEW SCHEME OF MULTICHANNEL SIGNAL MULTIPLEXING AND TRANSMISSION, NAMELY COHERENCE LENGTH MULTIPLEXING (CLM). ANALOGOUS TO WAVELENGTH DIVISION OR TIME DOMAIN MULTIPLEXING, CLM WHICH MAKES USE OF THE COHERENCE HOLOGRAPHIC FILTERS DEVELOPED IN THIS RESEARCH, WILL FIND APPLICATIONS IN FIBER OPTIC COMMUNICATIONS.