Effects of Phase Conjugation and of Coherent and Incoherent Beam Couplings in Reflection and Transmission in BaTiO3

We reported recently1 coherent beam couplings with He-Ne laser in reflection and transmission in electrically poled BaTiO3. We report here effects of phase conjugation on reflection and transmission. The effects of coherent and incoherent beam couplings on reflection and transmission will be compared. The experimental configuration used in the present experiments is shown in Fig. 1a. Two mutually coherent beams A1 and A2 from a He-Ne laser (6328Å) cross in the BaTiO3 crystal at 5°, with A1 and A2 making 73° and 78° with the c axis respectively. A third beam A3 from a second laser (6328Å) makes a crossing angle of 11° with A1 in the crystal. The self-pumped phase conjugate A←1(t) of the beam A1, its transmitted part A1T1 after one reflection and the specular reflection A1R1 are examined along with the subsequent transmission and reflection beams A1T2 and A1R2 respectively. The development of these five different beams is shown in Fig. 1b. Fig. 2 shows the specular reflection A1R1, being steady for a while, begins to go down as the self-pumped phase conjugate A←1(t) and the transmission beam A1T1 develop, and saturates at a lower intensity level.