2-WAVE COUPLING AND SELF-PUMPED PHASE CONJUGATION AT NEAR-INFRARED WAVELENGTHS IN BATIO3

Using an undoped BaTiO3 crystal, the reflectivities of the self-pumped phase-conjugate mirror operated in total internal-reflection geometry (TIR) at near infrared wavelengths from 706 to 850 nm were measured. The phase conjugation reflectivities R(pc) > 50% at 706 to 760 nm, R(pc) = 40% at 816 nm, and R(pc) = 20% at 850 nm were observed. The two-wave coupling exponential gain coefficient-GAMMA and the photorefractive index grating formation rate tau(PR)-1 as a function of wavelength from 706 to 850 nm were studied. The exponential gain coefficients-GAMMA = 11.1 cm-1 at 706 nm and GAMMA = 7.6 cm-1 at 850 nm were obtained. It was also found that the absorption coefficient-alpha in the near infrared wavelengths is much smaller than that in the visible region.