Third order nonlinear optical effects of ZnO–ZrO2–B2O3 glass ceramics embedded with ZnZrO3 perovskite crystal phases

Abstract

Zinc zirconium borate glasses crystallized with varying concentrations of ZrO2 by heat treating at the onset of the predicted crystallization temperature for prolonged times have been fabricated. The prepared samples were characterized by XRD and SEM techniques. The results of these measurements have indicated that the bulk samples are entrenched with ZnZrO3 (tetragonal/cubic) crystal phases with varying sizes and concentration, depending upon the content of ZrO2 present in the bulk material. The IR spectral studies have further confirmed that the zirconium ions mainly exist in octahedral coordination that are predicted to play crucial role in inducing third harmonic generation (THG). Later, the samples were optically poled by cw 532 nm green laser along with illumination by 9.4 μm CO2 laser. The infrared laser (CO2 laser) treatment was performed before the 532 nm laser treatment in order to activate the phonon modes (both harmonic and anharmonic modes). Later, intensity of the induced THG (of wavelength 355 nm) of the pre- and post-heated samples was measured using Nd:YAG 1064 nm 20 ns pulsed laser with the fundamental beam power varying up to 200 J/m2. The measurements were performed as functions of power of photoinduced 532 nm cw laser beam and also the concentration of the crystallizing agent ZrO2. Quantitative analysis of these results indicated that the samples crystallized with 5.0 mol% of ZrO2 exhibited the maximal intensity of THG. Further, the comparison of the obtained results with those of corresponding pre-crystallized samples pointed out that the crystallization has enhanced the THG intensity by many folds. The enhancement is attributed to the presence of ZnZrO3 perovskite crystal phases embedded in the residual glass phase of the bulk crystallized samples. The obtained results may be useful for considering the material for different optoelectronic devices especially for nonlinear optical triggering devices.