C. Gomezreino et al., NUMERICAL APERTURE FOR GRADED-INDEX TAPERED PLANAR WAVE-GUIDES WITH AHYPERBOLIC SECANT REFRACTIVE-INDEX PROFILE, J. mod. opt., 45(9), 1998, pp. 1785-1795
A study of the numerical aperture for graded-index tapered planar wave
guides with a hyperbolic secant refractive index profile is presented.
Results are particularized for divergent conical and convergent parab
olic types of the taper function.