Narrow spectral linewidth 1.5 mu m GaInAsP/InP distributed Bragg reflector (DBR) lasers

The spectral linewidth of distributed Bragg reflector (DBR) lasers is discussed. The narrowest linewidth of 3.2 MHz was obtained at P=1.5 mW. It was found that narrow spectral linewidths can be obtained constantly for the DBR lasers with long and low optical loss corrugation regions, and with a small coupling coefficient. These results are explained by the external cavity model, which is used in the theoretical analysis. To increase the output power of the narrow-linewidth DBR lasers, AR (antireflection) coating was applied to the output facet. Improved quantum efficiency and submode suppression were achieved. Degradation of the linewidths by the AR coating was insignificant.<
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