Xf. Tang et al., OBSERVATION OF BISTABILITY IN GAAS QUANTUM-WELL VERTICAL-CAVITY SURFACE-EMITTING LASERS, IEEE journal of quantum electronics, 33(6), 1997, pp. 927-932
Two different types of bistability in proton-implanted GaAs quantum-we
ll (QW) vertical-cavity surface-emitting lasers (VCSEL's) have been ob
served. The first type of bistability has a small hysteresis width (si
milar to 50 mu A) in the light versus current and voltage versus curre
nt characteristics. Light-induced large negative differential resistan
ce, random fluctuations, and self-pulsations are observed at the switc
hing point. The emission patterns show that the bistability occurs at
a spatially localized area under the output facet that covers only a s
mall fraction of the similar to 15-mu m-diameter aperture. The bistabi
lity stems from spatially localized saturable absorption. The second t
ype of bistability has a large hysteresis width (similar to 1 mu A) in
the L-I characteristics and is observed well above the threshold curr
ent. In this case, no observable bistable loop exists in the voltage v
ersus current characteristics, and the bistability is associated with
transverse mode-hopping.