The effect of wall tilt on the performance of directional couplers has been studied. There is a significant reduction in the coupling length as the tilt decreases when nonvertical walls, which are inherent in nearly all clean-room waveguide fabrication processes, are considered. Comparison of 90° and 45° coupling lengths reveals a difference of nearly a factor of 2 between them. Experimental data obtained with antiresonant reflecting optical waveguide directional couplers confirm that tilt effects should be considered in any device with large core thickness.
© 2002 Optical Society of America
A. Llobera, I. Salinas, I. Garcés, A. Merlos, and C. Domínguez, "Effect of wall tilt on the optical properties of integrated directional couplers," Opt. Lett. 27, 601-603 (2002)