Perturbation Analysis of Finlines Containing Anisotropic Media

is a genuine feature of this laser configuration, that also appears in other calculations. As can be concluded from Fig. 3, the use of a.efI in eqn. 1 is essential for a reasonable linewidth calculation of DFB lasers with a reflecting end facet. It can be shown that a comparably strong effect also occurs for two reflecting end facets with KL>2 and in the case of the phase-shifted DFB laser with at least one reflecting end facet (reflectivity 32%). The effective linewidth enhancement factor xeff in DFB lasers usually differs from the material a. factor. In typical devices, the linewidth can differ by about a factor of five depending on the spectral position of the lasing mode relative to the Bragg wavelength. No changes occur in the phaseshifted DFB laser. With reflecting end facets, (1 + &\n) can vary even by about an order of magnitude independently of a phase shift. It should be stressed that for xeff ^ a several other laser properties such as the stability or carrier number fluctuations become modified.