Gain-coupled DFB laser with index coupling compensation
 A gain-coupled distributed feedback (DFB) laser or amplifier structure having a gain-coupling grating in the form of grooves periodically etched through strained, multi-quantum wells. The etched grooves are regrown with buffer material having a bandgap selected to compensate for index-coupling aid to block carrier leakage. The low carrier leakage reduces non-radiative recombination which in turn increases quantum efficiency. 
Northern Telecom Limited
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additional inventional
Toshi Guo P.
Makino Li