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To pinpoint the driving forces behind the random lasing in Nd3+ doped lanthanum lead zirconate titanate (Nd:PLZT) ceramic plates, a combinatorial cavity with two gain media (Nd:YVO4 and Nd:PLZT) was used to study the switching feature between conventional lasing and random lasing oscillations. The complex laser output dynamics observed hinted that the photo-induced charge accumulation on the plate surface and the grain boundaries of Nd:PLZT is responsible for the lasing action switching, which was confirmed by a series of experiments, including strong electro-induced scattering, remarkable photoinduced currents, and light transmission reduction, along with measured single-pass-gain over the theoretical limit. It was found that the charge accumulation results in optical energy storage and nonuniform refractive index and hence strong scattering, which give rise to the random walks and weak localization of photons and long lasting lasing action and mode switching.

Obvious photochromic effects were observed in Pb(Zr,Ti)O3 and (Pb,La)(Zr,Ti)O3 (PLZT) ceramics, along with exponential responses to illumination power in both darkening and bleaching processes. An interesting anomalous dispersion in the transparent PLZT was observed and discussed. A tentative physical picture based on photoinduced electron stimulated processes and on structural change was proposed to explain all the interesting observations. Rate equations were established and solved in verifying the validity of the proposed model. This work may serve as guidance in designing tunable achromatic lenses, UV and IR light detectors and sensors.

Multi-mode random lasing action and weak localization of light were evidenced and studied in normally transparent but disordered Nd3+ doped (Pb,La)(Zr,Ti)O3 ceramics. Noticeable localized zone and multi-photon process were observed under strong pumping power. A tentative phenomenological physical picture was proposed by taking account of diffusive process, photo-induced scattering, and optical energy storage process as dominant factors in elucidating the weak localization of light observed. Both the decreased transmittance (increased reflectivity) of light and the observed long lasting fading-off phenomenon supported the physical picture proposed by us.

Remarkable enhancement/reduction of light emission and competition among different wavebands with rare earth doped lanthanum lead zirconate titanate ceramics were observed in a corona atmosphere caused by an externally applied electric field. Quantum-mechanical analyses, based on variation of structural symmetry of the unit cell and hence the crystal field due to electrostriction, were given to elucidate the effect. Apart from the symmetry of crystal field, the obvious contribution from the optoenergy storage and weak localization of light involved were discussed. These results are promising in designing and implementation of lasers and sensors.