Modelling the Spectra of Distributed Feedback Lasers

Abstract

<p>Distributed feedback (DFB) semiconductor lasers have a periodic modulation of refractive index, or Bragg grating, in the active region of the device. The Bragg grating causes a wavelength dependent distributed feedback of light. This thesis develops a below-threshold model for the spectra of DFB lasers. The model is shown to treat spontaneous emission in a manner that is quantum mechanically correct. Most other models in the literature do not treat spontaneous emission correctly, and are shown to yield spurious spectral predictions for truncated quantum-well DFB lasers. Techniques for fitting the model to spectral data are explained, and the model is demonstrated to be a useful diagnostic tool for understanding the performance and behaviour of DFB lasers. The effects of facet phase on DFB laser spectra are documented and explained. The model is then expanded to the above threshold regime, and is used to predict correctly spatial hole burning phenomena in DFB laser spectra.</p>