CsLiB_6O_10 crystallites embedded into the photopolymer matrices as promising materials for acoustically induced electrooptics

摘要

Acoustically induced linear electrooptics effects (LEOE) in CsLiB_6O_10, (CLBO) nanocrystallites incorporated into the olygoether photopolymer matrices have been revealed at liquid helium temperature (4.2 K). The LEOE has been measured for the source wavelength of a He--Ne laser (λ = 0.63 μm). With increasing acoustical power, the LEOE signal increases and achieves its maximum at an acoustical intensity of about l8.5 W cm 2 and a frequency of about l4 kHz. The value of the LEOE r_222 tensor component was comparable with that for the traditional nonlinear optical crystals, such as KH_2PO_4, KTiOPO_4 and LiNbO_3. With decreasing temperature (below 25 K), the acoustically induced LEOE signal strongly increases. A correlation between the acoustically nonlinear optical response and low-frequency Raman intensities has been found. The maximal acoustically induced SHG has been observed for the nanocrystallite concentration of about 3.1/100 (in weight units) and nanocrystallite sizes lying within 35-40 nm. The LEOE tensor coefficients were larger than for the bulk CLBO crystals (at least 21/100). Advantages and drawbacks of the presented model were discussed. The origin of the observed phenomena is explained on the ground of the ab initio band energy calculations taking into account anharmonic electron--phonon interactions.