FORMATION OF BIDOMAIN STRUCTURE IN SINGLE CRYSTAL LITHIUM NIOBATE QAFERS USING STEADY-STATE EXTERNAL HEATING METHOD

Abstract

The method of bidomain structure synthesis in lithium niobate single crystal wafers based on the formation of a specific temperature gradient across the sample thickness has been developed. The lithium niobate wafer placed between two silicon wafers was heated due to the absorption of light annealing system radiation by silicon. The work cell design allows one to form and control the power of thermal fluxes entering the ferroelectric wafer thus creating temperature gradients required for a controlled process of formation of two domains with opposite polarization vectors («head to head» domain structure). The efficiency of light absorption for the formation of external thermal sources that allow one to implement symmetric and asymmetric heating, determining the position of the conditional surface with the zero temperature gradient and consequently the position of the domain boundary is experimentally confirmed.In a lithium niobate wafer 1.6 mm in thickness and 60 mm in length, a symmetrical bidomain structure with opposite polarization vectors was formed. The bending strain of cantilevered samples vs applied voltage was investigated in the -300 to +300 V voltage range, the strain amplitude being more than 35 µm. The measurements showed a high linearity and repeatability of the bias voltage vs bending strain curve.