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 inward-going 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, scalar-field treatment, the vector-field 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