Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, Fujian Provincial Key Laboratory for Photonics Technology, Institute of Laser and Optoelectronics Technology, Fujian Normal University, Fuzhou 350007, China
Definitions of mode-field half-width and divergence half-angle according to different kinds of methods are analyzed in this work. Numerical results of these definitions are given for the fundamental mode and suggest that some of them are more suitable for describing the transmission characteristics of a slab waveguide.