Investigation On Photorefractive Phase Conjugation

Photorefractive effect is an in-linear optical phenomenon on electro-optic materials refractive index change with space distributive incident beam intensity. In this thesis,we investigate the properties of the phase-conjugate wave produced by the self-pumped and mutually pumped in KNSBN crystal according to need for application in practice.Based on fanning effect experiment in KNSBN crystal,the influence of incident spot diameter on fanning effect is studied. Relative transmitted intensity decrease and scattering intensity increase are found with incident spot diameter increase for the same incident position, angle and intensity. The action of incident spot diameter in fanning effect mechanism is analyzed theoretically. The relation between incident spot diameter and two-wave coupling interaction region is built and theoretical modeling is given on the experiment result. In a word, the research lays theoretical and experimental foundation to for utilization and suppression of fanning effect.Experimental studies on the effect of the incident location and incident light spot size on the KNSBN crystal self-pumped phase conjugation characteristics was carried out,and the result shows there exist relations between the location of the incident of self-pumped phase-dependent and the reflectivity of the incident light spot. The research also proves the incident light spot size of the self-pumped changes with uniform light scrub and non-scrub on the self-pumped phase conjugation situation when the incident location and incident angle are not varied.The phase conjugation properties of KNSBN crystal with two symmetrical incident beams are investigated when self pumped phase conjugation(SPPC)and mutually pumped phase conjugation(MPPC)coexist. The coexistent condition is introduced in the study,and the coexistence of self-pumped phase conjugation and mutually pumped phase conjugation in the photorefractive crystal is realized in the unsymmetrical incident.