Maker-fringe analysis and electric-field poling of lithium niobate.

摘要

This dissertation focuses on Maker-fringe analysis and electric-field poling of z-cut lithium niobate (LiNbO3). The Maker-fringe analysis involved examining second-harmonic generation (SHG) as a function of pump beam angle of incidence, where four separate pump-SHG polarization orientations were examined. The theoretical model developed here to describe the Maker fringes includes the full birefringent of this uniaxial material. The theory also considers Fabry-Perot resonances of both the pump and second-harmonic waves in the sample. Simultaneously fitting all four pump-SHG orientations to sample thickness, ordinary index of refraction at the pump and second-harmonic wavelengths, and extraordinary index of refraction at the pump and second-harmonic wavelengths has led to the most comprehensive Maker-fringe analysis attempted to date. From this analysis, index of refraction variations lead to a description of the compositional variation within a wafer and between wafers. Other properties that may also be determined are the nonlinear coefficients d2ij , electrooptic coefficients rij, surface charges, internal fields, stresses, and strains. Any effect that perturbs the indices of refraction by 1 x 10--5 or more can be examined.; The Maker-fringe analysis revealed that the extraordinary index of refraction of LiNbO3 is smaller than that predicted by the commonly used Sellmeier equation derived by Edwards and Lawrence [Edwards '84]. The discrepancy is on the order of --9 x 10--4 at a wavelength of 532 nm and appears to be related to the compositional variation between the congruent material used in the original index studies and that, which is currently available. Maker-fringe analysis has also been used to measure the nonlinear coefficients d231 = 5.95 pm/V and d233 = 25.2 pm/V, electrooptic coefficients rT13 = 1.27 x 10--5 mm/kV and rT33 = 3.44 x 10--5 mm/kV at a wavelength of 1.064 mum, and rT13 = 1.39 x 10--5 mm/kV and rT33 = 3.43 x 10--5 mm/kV at a wavelength of 532 nm, and pyroelectrically induced electric fields up to --19.1 kV/mm after a 200°C temperature cycle.; The electric-field poling experiments involved examination of the poling current with respect to the applied poling field and Maker-fringe analysis of domain-reversed material. I observed a similar offset in the behavior of the poling current (6.9 kV/mm) as other researchers have seen in polarization hysteresis loops (6.7 to 7.0 kV/mm). I also correlated this offset with the observation of fringe shifts in the Maker-fringe scans of domain reversed material.