Electric field tunable diffraction optical element based on strontium–barium niobate single crystals

In this paper, we present the electric field controllable diffractive optical elements in strontium–barium niobate single crystals with stable tailored spiral-shaped domain structure and demonstrate the generation of optical beam with orbital angular momentum. The required domain pattern was created in the sample with initial domain structure by electric field application using the photolithographically defined liquid electrode. A series of bipolar triangular electric field pulses were applied to the sample for determination of the optimal parameters for complete polarization switching under the electrode. The stable tailored domain pattern of the spiral shape was created by the application of the unipolar pulse of a special shape. The complete switching under the electrode and partial switching under the photoresist layer have been revealed. The imaging by Cherenkov-type second harmonic generation microscopy confirmed that the created domain structure reaches the opposite polar surface. The imaging of the diffraction pattern of the laser beam passing through a voltage-biased DOE confirmed the formation of the beam with orbital angular momentum. The half-wave voltages of 237[Formula: see text]V and 302[Formula: see text]V for wavelength 632.8[Formula: see text]nm and 532[Formula: see text]nm, respectively, for 2-mm-thick sample were measured. The obtained knowledge can be used for the development of domain engineering methods in strontium–barium niobate single crystals for the creation of tailored domain structures for manufacturing of electric field controllable diffractive optical elements.