Proton-exchanged periodically segmented channel waveguides in lithium niobate

Annealed proton-exchanged periodically segmented channel waveguides were fabricated in Z-cut lithium niobate. The propagation losses as a function of the duty cycle and the segmentation period are reported. Waveguiding was observed at large segmentation periods, up to 100 μm. For duty cycles >0.5, the propagation losses are nearly the same as measured for a continuous waveguide with the same width, namely ~1.45 dB/cm. With decreasing duty cycle, the mode expands in the transverse directions