Optical phase and amplitude modulation in (9/65/35) Pb-La-Zr-Ti-O thin films

Electro-Optic Pb0.9tLa0.09Zr0.65Ti 0.35O3 (PLZT) thin films are studied for transverse optical modulator applications. PLZT thin films were grown by pulsed laser ablation on MgO and GaAs substrates. Structural characterization by x-ray diffraction, transmission electron microscopy, Rutherford backscattering, and sputter Auger electron profiling indicate polycrystalline, phase pure PLZT with evidence of interdiffusion and approximately 20nm RMS surface roughness. Single PLZT thin films, grown on MgO substrates with a SrTiO3 (STO) buffer layer, were fabricated into simple modulator structures for electro-optical characterization. Measurements were performed in normal transmission mode. Application of an oscillating electric field across the PLZT layer produced optical amplitude and phase modulation. The application of an oscillating electric field of frequency f across the PLZT has been observed to produce f and 2f frequency modulation in both the phase and amplitude of the output light. Theoretical considerations show that this can be attributed to the quadratic nature of the electro-optic effect in PLZT. ©1999 Materials Research Society.