Simple methods for measuring the linewidth enhancement factor in external cavity laser diodes

We introduce two simple methods, a current scanning method and a reflectivi ty scanning method, for measuring the linewidth enhancement factor(Lu) in a n external cavity laser diode (ECLD). Both methods utilize the functional r elationship associated with a between the emission wavelength and effective reflectivity of the compound cavity of ECLD. The change of emission wavele ngth as a function of an injection current and of an external reflectivity is used to determine the value of a in the current scanning method and in t he reflectivity scanning method, respectively. The measured values of a: by the two methods showed a fairly good agreement. (C) 2000 Elsevier Science B.V. All rights reserved.