Anisotropic polarization characteristics of lasing and spontaneoussurface and edge emissions from deep-ultraviolet ( λ ≈ 240 nm ) AlGaN multiple-quantum-well lasers

The authors report on their experimental discovery of a transverse-magnetic-field (TM)-mode polarization of lasing and spontaneous edge emissions (anisotropic polarization emissions) above and below the lasing threshold from the AlGaN multiple-quantum-well (MQW) laser at 240.8 nm . The deep ultraviolet MQW emitted very weak or no surface emission (anisotropic polarization emission) below the threshold. On the other hand, the AlGaN multiple-quantum-well laser at 355.1 nm operated in the transverse-electric-field (TE) mode above the threshold, and homogeneous high-intensity spontaneous surface emission and both TE- and TM-mode edge emissions (isotropic emissions) were observed below the threshold.