Radiation loss in tapered waveguides
Abstract
The eikonal or localnormalmode (LNM) approximation method is presented and applied to the investigation of the radiation loss of a TE guided mode that is due to a narrowing linear taper in slab geometry using a weakcoupling approximation. An exact expression for the total radiation loss is given within the limits of the theory, these limits being small refractiveindex changes per wavelength. An approximation to the loss expression is evaluated numerically, indicating that the total radiative loss is roughly exponentially dependent on mode number and on taper step size, at least for weak tapers. The method developed here is not restricted to tapered structures but can be readily adapted to any type of longitudinal disturbance.
 Publication:

Journal of the Optical Society of America (19171983)
 Pub Date:
 September 1981
 Bibcode:
 1981JOSA...71.1107T
 Keywords:

 Eikonal Equation;
 Integrated Optics;
 Optical Waveguides;
 Propagation Modes;
 Refractivity;
 Transmission Loss;
 Approximation;
 Eigenvalues;
 Radiation Distribution;
 Wave Dispersion;
 Wave Propagation;
 Optics