Observations of negative resistance associated with superlinear emission characteristics of /Al,Ga/As double-heterostructure lasers

The paper reports observations of the electrical and optical behavior of stripe-geometry, photon bombardment delineated, (Al,Ga)As double-heterostructure lasers whose output power shows an abrupt, nearly discontinuous increase as a function of input current. When operated within this superlinear regime, the averaged output power fluctuates randomly between levels corresponding to the intensities at either end of the superlinear range. A negative resistance which is light induced and is associated with the lasing optical field accompanies the superlinearity; the low temperature behavior of the negative resistance shows that nonohmic conduction mechanisms are present in the laser material. However, axially nonuniform changes in the luminescence observed through the substrate indicate that saturable optical absorption in the active layer at the laser mirror faces may be the predominant cause of the superlinearity and negative resistance.