GAIN-GRATING ANALYSIS OF A SELF-STARTING SELF-PUMPED PHASE-CONJUGATE ND-YAG LOOP RESONATOR

We investigate both experimentally and theoretically the contribution of the different gain gratings in a self-starting self-pumped phase-co njugate Nd:YAG loop resonator, Thanks to a transient model, we show th at the transmission-grating configuration is more efficient than the r eflection-grating configuration, and that their temporal dynamics are different, in agreement with the experiment, Maximum extraction is obt ained for the four-grating configuration. The output beam is a high-qu ality diffraction-limited TEM00 mode, even with severe intracavity pha se aberrations, and has a single-longitudinal-mode pulse shape of simi lar to 13 ns, with maximum energy of similar to 130 mJ up to 30 Hz. We also investigate the role of the output coupler reflectivity on the o utput pulse energy and formation. Finally, the influence of the differ ent gratings on the ability of such a self-starting loop resonator to correct for polarization distorsions is studied.