Linewidth enhancement factor in InGaAsP/lnP modulation-doped strained multiple-quantum-well lasers

Reduction of the linewidth enhancement factor /spl alpha/ is studied in InP-based strained multiple-quantum-well (MQW) lasers. Theoretical analysis shows that the /spl alpha/-parameter is greatly reduced in modulation-doped strained MQW lasers and may be zero while keeping positive gain. The experimental evaluation exhibits a very small /spl alpha/-parameter of around 1 in InGaAsP/InP modulation-doped strained MQW lasers. As a result of the small /spl alpha/-parameter, the linewidth-power product is effectively reduced in 1.5-/spl mu/m DFB lasers with the modulation-doped strained MQW structure. A narrow spectral linewidth around 100 kHz was also obtained reproducibly in 1.5-/spl mu/m modulation-doped strained MQW DFB lasers.<
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