The temperature dependent electrostrictive effect, with respect to increasing the cooling rate to a cooling temperature, was quantitatively investigated in potassium tantalate niobate (KTN) lead-free single crystals above and near Curie temperature (TC). High work-function Pt electrodes are used to minimize the effect of charge injection, and the electric field induced displacement was measured with Michelson interferometry. It was found that a giant electrostrictive coefficient of 696 × 10−16 m2/V2 could be obtained at a high cooling rate of 0.75 °C/s to a temperature of TC + 4.5 °C due to the evolution of polar nano-regions, which is one order of magnitude larger than the previously reported value in KTN crystals. This strengthens the realization of replacing toxic lead-based electrostrictive materials with environmentally friendly KTN materials in real world applications.

In this paper, we report a three orders-of-magnitude increase in the speed of a space-charge-controlled KTN beam deflector achieved by eliminating the electric field-induced phase transition (EFIPT) in a nanodisordered KTN crystal. Previously, to maximize the electro-optic effect, a KTN beam deflector was operated at a temperature slightly above the Curie temperature. The electric field could cause the KTN to undergo a phase transition from the paraelectric phase to the ferroelectric phase at this temperature, which causes the deflector to operate in the linear electro-optic regime. Since the deflection angle of the deflector is proportional to the space charge distribution but not the magnitude of the applied electric field, the scanning speed of the beam deflector is limited by the electron mobility within the KTN crystal. To overcome this speed limitation caused by the EFIPT, we propose to operate the deflector at a temperature above the critical end point. This results in a significant increase in the scanning speed from the microsecond to nanosecond regime, which represents a major technological advance in the field of fast speed beam scanners. This can be highly beneficial for many applications including high-speed imaging, broadband optical communications, and ultrafast laser display and printing.

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To overcome the depth limitation of the space-charge-controlled (SCC) potassium tantalate niobate (KTN) deflectors, we report in this paper a method of increasing the aperture of SCC-KTN deflectors by harnessing the physical mechanism of blue light photon excitation. The experimental results show that the deflection angle can be increased from 0.7 mrad without the blue light excitation to 2.5 mrad with the blue light excitation at a penetration depth of 5 mm under the same external applied voltage, which is consistent with the theoretical analysis. This represents a substantial increase in the deflection angle at a much deeper penetration depth, which can be very useful for applications such as high speed 3D printings and displays.

In this paper, a high-speed non-mechanical two-dimensional KTN beam deflector is reported. The scanning mechanism is based on the combination of space charge controlled beam deflection and temperature gradient enabled beam deflection in a nanodisordered KTN crystal. Both theoretical analyses and experimental investigations are provided, which agree relatively well with each other. This work provides an effective way for realizing multi-dimensional high-speed non-mechanical beam deflection, which can be very useful for a variety of applications, including high-speed 3D laser printing, high resolution high speed scanning imaging, and free space reconfigurable laser communications.