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Electro-optic (EO) devices with high EO coefficients at radio and microwave frequencies are integral components of the photonics industry. This work determines the EO effect of ferroelectric Li-doped niobium-rich potassium tantalate niobate (K 0.95 Li 0.05 Ta 1- x Nb x O 3 ; KLTN) single crystals using improved dynamic EO measurement. The phase transitions of KLTN crystals were investigated via variable-temperature Raman spectroscopy. A full view of the surface displacement and velocity for the KLTN sample at the resonant frequency was studied using an ultra-frequency vibrometer. The KLTN sample with x = 0.60 exhibits the enhanced effective EO coefficient (γ c ) ∼ 217 pm/V near the piezoelectric resonant peaks, which is comparable with the value at low frequency. The piezoelectric enhanced EO property of KLTN single crystals can be attributed to nonlinear polarization and nonzero stress, and showing promising for designing practical optical-piezoelectric-mechanism coupling devices.

In our continuing effort of developing electromagnetic-electromechanical-electrooptic interactive devices, the effect of piezoelectric resonance on the performance of electrooptic modulators is investigated. Time domain finite element models were constructed to determine the phase shift due to the induced birefringence of the device. Two sinusoidal voltage sources are used one to sweep over a range of frequencies while the other setting the modulator at a selected resonance frequency. Ferroelectric single crystals such as LiNbO 3 and Pb(Zn 1/3 Nb 2/3 )O 3 -PbTiO 3 , were examined for their induced index of refraction, the induced phase shift, and the half-wave voltage of given configurations. The time domain model of dual signal ac biased configuration displayed wide bandwidth enhancement when biased at proper resonant modes, which matches well with experimental observations. The results demonstrate the piezoresonant enhancement in terms of low half wave voltage and high electrooptic coefficients in broad frequency ranges. The results also provided corresponding insights that further our understanding on experimental observations reported previously by the authors. The models are suitable for designing of electrooptic device configurations that optimize the properties desired.

A study of the acousto-optic (AO) effect in a family of oxide crystals (including e.g., TiO2, ZnO, LiNbO3, and ferroelectric perovskites) as well as semiconductors has been conducted by finite element analysis method. In addition, the acousto-optic figure of merit (FOM) as a function of material's refractive index, density, effective AO coefficient and the velocity of the acoustic wave in the material, is also investigated. By examining the directional dependent velocity, acousto-optic coefficients, and refractive index, the acousto-optic FOM can be calculated and plotted in all directions revealing the optimal crystal orientation to maximize coupling between the optical and acoustic waves. A finite element model was developed to corroborate the predicted interaction. The model examines the diffraction that occurs by the optical wave as it travels through an acousto-optic medium. The combined information gained from Mathematica and COMSOL Multiphysics-based modeling is shown to be an effective means of predicating acousto-optic device functionality.

Single crystal silicon exhibits thermal, mechanical, optical, and fabrication properties appropriate for the requirements of HEL (High-Energy Laser), component technology. As a material, single crystal silicon offers low thermal expansion, low density, high thermal conductivity and high heat capacity which yield a thermal/mechanical high power deformation response that is superior to Mo, Be, WC and other mirror candidate materials. In addition, silicon's crystal structure can be used to produce periodic, sharply defined geometrical shapes in certain crystallographic planes through Preferential Chemical Etching (PCE). By properly combining this action with specific photoresist exposure and development techniques, coolant channels and other critical structures related to HEL component fabrication may be produced accurately. Silicon also can be polished to a low microroughness, yielding surfaces with low scatter and high damage resistance. These advantages apply to both CW and pulsed modes of operation, providing the potential for high quality operation at short as well as long wavelengths.© (1981) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.