Circularly symmetric distributed feedback laser  Coupled mode treatment of TE vector fields
Abstract
The vector orientation of transverse electric (TE) fields in deriving coupled mode equations for radially outward and inwardgoing modes in a circular waveguide diffraction grating is treated. The equations are derived for cylindrical waves in a system that is translationally invariant along the cylinder axis; the derivation is then extended to the waveguide geometry. The coupled mode equations are used to describe the operation of the circularly symmetric distributed feedback (DFB) laser. While predicting a similar dependence of the laser threshold gain on an azimuthal mode order to that found by a simpler, scalarfield treatment, the vectorfield treatment predicts a fundamental difference in the location of the cavity resonances. The circular DFB laser is expected to lase in multiple azimuthal modes but maintain a relatively narrow overall spectral width.
 Publication:

IEEE Journal of Quantum Electronics
 Pub Date:
 March 1992
 DOI:
 10.1109/3.124985
 Bibcode:
 1992IJQE...28..612E
 Keywords:

 Circular Waveguides;
 Coupled Modes;
 Distributed Feedback Lasers;
 Gratings (Spectra);
 Surface Emitting Lasers;
 Vector Spaces;
 Bessel Functions;
 Green'S Functions;
 Laser Cavities;
 Wave Equations;
 Lasers and Masers