A new phase-conjugated laser resonator has been designed and successfully operated. The resonator, shown in Fig. 1, incorporates a phase-conjugating (PC) mirror consisting of a lens and a stimulated Brillouin scattering (SBS) cell placed conveniently in a side arm. The SBS cell contained either carbon disulfide or cyclohexane. The gain medium was an antireflection-coated Nd:YAG rod 6 mm In diameter × 75 mm long. The quarterwave plate was placed in a rotatable mount. The degree of coupling between the PC mirror and the rest of the resonator could be varied simply by rotating the optic axis of the quarterwave plate. When the optic axis was either parallel or perpendicular to the transmission direction of the polarizer, the PC mirror was completely decoupled from the rest of the cavity, and the laser operated like a conventional laser in a long pulse mode. Maximum coupling with the PC mirror occurred when the optic axis was at 45° to the transmission direction of the polarizer. When the wave plate optic axis was rotated 2° from the maximum coupling position, a Q-switched energy output of 250 mJ at the 1.06-μm wavelength was obtained with 20-J energy input using cyclohexane as the SBS medium. Carbon disulfide yielded 40% less output.
© 1984 Optical Society of AmericaPDF Article