Coupling radiation out of a distributed-feedback semiconductor laser excited by an electron beam

Dependences of the quantum efficiency on the length of the active region were determined experimentally for a distributed-feedback semiconductor laser pumped by an electron beam. The output radiation was coupled out through the surface or end of a waveguide. The dependences obtained were compared with circulations. It was found that the eRiciency of coupling out of the radiation through the surface of the waveguide could be greater than the efficiency of coupling out through its end. A relationship was found between the dependence of the quantum efficiency on the length of the active region and the distribution of the intensity along the laser axis.