Photo-induced Domain Inversion for Electrooptic Devices

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Domain inversion of an electrooptic crystal makes ultrafast -optical spatial modulation possible. We have developed ultrafast electrooptic modulators, which separate and control optical frequencies with domain inversion, such as an electrooptic deflector, a wave-front controller, an aberration corrector, a phase grating and their integrated devices.In order to develop novel electrooptic devices with domain inversion, it is important to make precise and reproductive domain inversion. First, we studied on ordinary domain inversion by applying DC high voltage. As the result, it is found that the inversion current must be stopped before no later than decreasing to its leaky revel. Domain inversion with pulse high voltage was suitable for the current control by monitoring number of pulses with current shapes.Damage thresholds of electrooptic crystals were tested by applying high-power YAG laser 3rd pulses of 6 ns duration. Up to the damage threshold, there were the circles of refractive index change according to the pulse diameter. After domain inversion with the pulse irradiation, it is found that domain inversion is also possible on the spots of refractive index change.