<title>Phase-conjugate characteristics of the terbium-copper-doped potassium sodium strontium barium niobate crystal</title>

Abstract

In this paper we demonstrate the phase conjugate characteristics of a Tb:Cu:KNSBN crystal, using the self- pumped phase conjugator, the bridge double phase conjugator and the coherently induced double phase conjugator, respectively. The experimental results show that the Tb:Cu:KNSBN crystal has high 'cat' self-pumped phase conjugate reflectivity, which is 57 percent at incident angle of 40 degrees and input intensity of 7.6 W/cm<SUP>2</SUP>, and fast response. For the bridge double phase conjugator, two mutually incoherent e-polarized input beams enter the opposite crystal faces symmetrically with an included angle of 112 degrees. We measured the maximum phase conjugate transmissivity of 65 percent and the maximum phase conjugate reflectivity of higher than 250 percent. Moreover, we found that the temporal phase conjugate output varies with which input beam being blocked before the measurement. A peak reflectivity of as high as 300 percent was obtained when the beam ratio is 6.5. The Tb:Cu:KNSBN crystal has also been used to implement the coherently induced double phase conjugation and phase conjugate reflectivity approximately 320 has been obtained in a very large dynamic range of beam ratios.