FACET PHASE EFFECTS IN DFB DIODE LASERS

Abstract

A transfer matrix model of distributed feedback (DFB) lasers was fit to experimental laser spectra, thereby extracting physical laser parameters. This was done in order to monitor facet degradation during aging studies of 11 DFB laser devices. Ten de vices had no observable spectral changes, and one device had spectral changes that could be fitted to by varying the model’s front facet phase and reflectivity parame ters. Comparison of this result with measurements of degree-of-polarization (DOP) photoluminescence maps ofthe laser facet showed a unique stress pattern on the facet that could possibly indicate changes in facet properties. The effective linewidth enhancement factor (LEF) and frequency response were measured from four devices to determine if spatial holeburning affects the dynamic behaviour of DFB lasers enough to cause performance differences between devices. No obvious differences between frequency responses of the four devices were observed, and LEF values of 5-6.5 were extracted from the response data. Comments on the validity of the LEF calculation are made.