Measurement of transverse electro-optic coefficient of Sr0.6Ba0.4Nb2O6 thin film grown on MgO substrate with different content of potassium ions

Preferred c-axis oriented Sr0.6Ba0.4Nb2O6 (SBN60) thin films doped with different content of potassium ion have been fabricated by the sol-gel process on MgO(001) substrates. The micro-structure and surface morphology of the films were studied by X-ray diffractometer and atomic force microscopy. It is found that the crystalline properties and the refractive index of the SBN60 films are closely related to the potassium ion concentration in the films. The measured transverse electro-optic coefficient r51 of the SBN60 thin films with K+ / Nb5+ molar ratios of 0, 1 / 7, 1 / 5, 1 / 3 and 2 / 3 are 36.85, 41.72, 43.11, 62.40 and 77.75 pm/V at 633 nm, respectively. An enhancement of r51 with K+ content in the SBN60 films has been clearly demonstrated.