A simple tapered directional coupler with a five-layered structure is employed for mode conversion between a single-order and higher-order modes. We investigate coupling from higher-order modes to a single-order field theoretically and experimentally. As a result, we confirm that the first two modes in the tapered waveguide are coupled with a single-order mode in another waveguide by computer simulation using the beam propagation method. Furthermore, we fabricated the actual device and observed the streak patterns of the first three modes.
© 1999 Optical Society of America
Hiroshi Komatsugawa, Masayasu Kamata, and Keisuke Sasaki, "Analysis of Mode Size Transformation with a Tapered Directional Coupler," Appl. Opt. 38, 4509-4515 (1999)