CPC H01S 5/3402 (2013.01) [H01S 5/1007 (2013.01); H01S 5/1014 (2013.01); H01S 5/1082 (2013.01); H01S 5/22 (2013.01)] | 20 Claims |
1. A quantum cascade laser (QCL) comprising:
a substrate; and
a semiconductor layer adjacent the substrate and defining
a plurality of branch active regions, and
a stem region coupled to output ends of the plurality of branch active regions;
each branch active region comprising
a plurality of laser cores, and
a plurality of spacer layers respectively interweaved between the plurality of laser cores,
a dielectric layer over the plurality of laser cores, and the plurality of spacer layers, the plurality of spacer layers extending laterally to the dielectric layer,
the plurality of laser cores having a number of stages less than 50.
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