Electro-optic mode deflection based on a lithium niobate waveguide with microstructured electrodes

Abstract

We propose the electro-optic mode deflection devices based on annealed proton exchange (APE) waveguides in lithium niobate with microstructured electrodes. Two mode deflection devices with right-triangle-shaped electrodes (Device A) and isosceles-triangle-shaped electrodes (Device B) are investigated. Taking advantage of the refractive index prism array formed when applying an external voltage to the electrodes, the mode can be deflected. Beam smoothing can be achieved by applying alternating voltages. A∼1.28 μm beam deflection is obtained by applying a voltage (20 V) for Device A. For Device B, a 3.52 μm beam deflection is obtained by applying a -15 V voltage to the electrodes. Device B has a horn-shaped input waveguide which ensures that the output is a quasi-single mode. The mode quality of the deflection beam is also quantified by the CMOS camera. Smoothing the non-uniform density distribution of light beam is confirmed by averaging over 69 images taken by the CMOS camera with alternating voltage. These electro-optic mode deflection devices have potential applications in electro-optic sampling, high-speed optical switch, and beam smoothing of a high-power laser.