Far field asymmetry in narrow stripe gain-guided lasers

A number of 5 μm stripe width shallow proton-bombarded double heterostructure (DH) AlGaAs LPE grown lasers show asymmetric light versus current characteristics and far fields. The optical power output above threshold is not the same for both faces at a given current. The far field patterns in the junction plane from the two mirrors are also different: the angular distribution of the optical power emitted in the junction plane is not the same for both mirrors. The asymmetry in the far fields is the subject of this paper. It is suggested that a large optical loss near the face with lower optical power output may explain the different far fields observed from the two mirrors. Possible explanations for the origin of this optical loss are discussed.