Optical properties of (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 single crystals

Optical properties of (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-xPT, x=5%, 9% and 12%) single crystals have been comprehensively investigated. The PZN-xPT single crystals used in this study were grown using a high temperature flux method. Refractive indices (nij) were measured by the Brewster’s angles (θB=tan-1n) at different wavelengths. Dispersion equations of refractive indices were obtained. After poled along [001] direction, the transmittance of PZN–12%PT single crystal is more than 65% from 0.5 to 5.8 μm, which is much higher than that of PZN–5%PT and PZN-9%PT single crystals. PZN–12%PT has a tetragonal phase, its spontaneous polarization PS is along [001] direction. After poling, it could form a single domain structure. Orientation and temperature dependences of the electro-optic coefficient were investigated at He-Ne laser by the Senarmont compensator method. Large effective electro-optic coefficient (γc = 430 pm/V) was observed in [001]-poled PZN-9%PT crystal. More importantly, γc of tetragonal PZN-12%PT is about 130 pm/V, which is almost unchanged in a temperature range -20~80 °C. The γc of PZN-xPT single crystals are much higher than that of widely used electro-optic crystal LiNbO3 (γc = 20 pm/V). These excellent optical properties make the PZNxPT single crystals promising candidates for electro-optic modulation applications.