Theoretical analysis of wavelength tuning in distributed-feedback lasers by quantum-well intermixing

Wavelength tuning in distributed-feedback (DFB) lasers using quantum-well intermixing is analyzed. A 0.42-nm tuning range is obtained when the bandgap is blue-shifted by 5.9 nm, and this value agrees well with the experimental value of 0.36 nm. The limitation of the tuning range is also discussed, and is because of the increase in carrier density that raises the gain above the threshold after intermixing. The dependence of wavelength shift on bandgap blueshift is not affected by the details of the intermixing process. A maximum tuning range of 3.5 nm is predicted, demonstrating that after device fabrication intermixing process can be used to adjust DFB lasers operating wavelengths to match the predefined wavelength channels of wavelength-division-multiplexing system.