Modulation resonance enhancement in SCH quantum-well lasers with an external Bragg reflector

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The modulation response of a semiconductor laser can be enhanced by coupling it to an external cavity with frequency-selective feedback. This creates a comb of transmission bands where the modulation response is high, at the cavity round-trip frequency and its harmonics. In a previous publication, we related the bandwidths of these bands to the material and structural parameters of a bulk laser. We showed that a nonzero linewidth enhancement factor together with a nonzero intermediate facet reflectivity lead to deep nulls close to the peaks of these transmission bands. This suggests that quantum-well (QW) lasers, which have a low linewidth enhancement factor, may give a better performance than bulk lasers. To test this hypothesis, we have extended our analysis to model QW lasers coupled to a fiber grating. Carrier transport, carrier heating, intraband carrier fluctuations, and nonparabolic band structures are considered. We show that electron carrier transport and amplitude-phase coupling in the separate-confinment-heterostructure (SCH) layer contribute to the nulls in the modulation response. Therefore, the apparent advantage of having a reduced linewidth enhancement factor that we found in our previous analysis cannot be fully realized by using QW lasers.

Original languageEnglish
Pages (from-to)716-728
Number of pages13
JournalIEEE Journal of Quantum Electronics
Issue number4
Publication statusPublished - Apr 1998
Externally publishedYes


  • External cavity
  • Fiber Bragg grating
  • Modeling modulation
  • Resonance enhancement
  • SCH quantum-well lasers

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