Comparison of lifetime and threshold current damage factors for multi-quantum-well (MQW) GaAs/GaAlAs laser diodes irradiated at different proton energies

Proton damage effects on multi-quantum-well (MQW) GaAs/GaAlAs laser diodes are studied using both current vs. voltage (I similar to V) and optical pow er vs. current (L similar to I) characteristics. The lifetime damage factor is calculated from I similar to V characteristics ana compared with the co mmonly used threshold current damage factor from L similar to I characteris tics. The lifetime damage factor is larger than the threshold current damag e factor. This difference is explained by the different values of radiative lifetime when measuring the damage factors in the different operating regi ons. The two damage factors are compared at proton energies from 70 MeV to 200 MeV.