The mode coupling among guided modes in a photorefractive crystal waveguide is investigated. We derive the coupled equations of guided modes in a photorefractive crystal waveguide. Analytical solutions of the coupled equations are obtained for a two-mode photorefractive crystal waveguide. We also numerically analyze the coupled equations of guided modes in a multimode photorefractive crystal fiber. As a result of the coupling, power may flow to the fundamental mode or the highest-order mode, depending on the direction of the crystal optical axis. In addition, we report an analytical solution of the modal power in core and cladding for all guided HE<sub>νm</sub> and EH<sub>νm</sub> modes for cylindrical fibers made of uniaxial crystals.
© 2000 Optical Society of America
Huang-Tzung Jan, Sien Chi, and Pochi Yeh, "Theory of mode coupling in a photorefractive crystal waveguide," J. Opt. Soc. Am. B 17, 1176-1181 (2000)