Slab waveguide tapers with finite cladding thickness are analyzed using a geometrical optics approach, and the results are compared with an exact modal analysis. Iteration formulas are derived for the calculation of the propagation angles of the guided modes and the corresponding changes in the core and cladding thicknesses, assuming that the difference between the refractive indexes of the core and cladding is small. Numerical results are presented and compared with the values obtained by a successive step modal analysis, showing good agreement between the two approaches. This indicates that ray tracing techniques should be useful for the analysis and design of taper couplers.
© 1978 Optical Society of America
B. K. Garside, T. K. Lim, and J. P. Marton, "Ray trajectories in optical fiber tapered sections," Appl. Opt. 17, 3670-3674 (1978)