MODULATION RESONANCE ENHANCEMENT IN SCH QUANTUM-WELL LASERS WITH AN EXTERNAL BRAGG REFLECTOR

The modulation response of a semiconductor laser can be enhanced by co upling it to an external cavity with frequency-selective feedback, Thi s creates a comb of transmission bands where the modulation response i s high, at the cavity round-trip frequency and its harmonics. In a pre vious publication, we related the bandwidths of these bands to the mat erial and structural parameters of a bulk laser, We showed that a nonz ero linewidth enhancement factor together with a nonzero intermediate facet reflectivity lead to deep nulls close to the peaks of these tran smission bands, This suggests that quantum-well (QW) lasers, which hav e a low linewidth enhancement factor, may give a better performance th an hulk lasers, To test this hypothesis, we have extended our analysis to model QW lasers coupled to a fiber grating, Carrier transport, car rier heating, intraband carrier fluctuations, and nonparabolic band st ructures are considered, We show that electron carrier transport and a mplitude-phase coupling in the separate-confinment-heterostructure (SC H) layer contribute to the nulls in the modulation response, Therefore , the apparent advantage of having a reduced Linewidth enhancement fac tor that we found in our previous analysis cannot be fully realized by using QW lasers.