title: Adiabatically tapered periodic segmentation of channel waveguides for mode-size transformation and fundamental mode excitation.
abstract: We report modeling, fabrication, and characterization of tapered waveguides, using periodically segmented annealed proton exchange in LiNbO(3). For a taper transforming the 1/e full width (intensity) mode size from 6.0 microm x 4.4 microm to 2.0 microm x 1.3 microm, 0.4-dB excess loss was observed. The large, slightly elliptical mode can ease coupling to single-mode fibers and circular free-space beams. The same taper structure was used to excite a highly multimoded (13 modes) waveguide with more than 95% of the power stably launched into the lowest-order mode. This function is useful for nonlinear waveguide devices, such as difference-frequency generators, in which modes at highly disparate wavelengths interact.
authors.forename: M H
authors.initials: MH
authors.lastname: Chou
authors.forename: M A
authors.initials: MA
authors.lastname: Arbore
authors.forename: M M
authors.initials: MM
authors.lastname: Fejer