Low-frequency current and intensity noise in AlGaAs laser diodes

Abstract

The current noise of 0.78 μm AlGaAs laser diodes has been measured at frequencies between 10 Hz and 100 kHz. A 1/ f noise behavior is found at low frequencies. The corner frequency of the current 1/ f; noise depends on the operating current level and is shifted to higher frequency with increasing pumping level. Lorentzian spectra due to generation-recombination (GR) processes have been found for the first time in semiconductor laser diodes in the current below threshold. This is attributed to defects existing in the structure of AlGaAs diodes. The activation energy of the trap is 135 mV. The intensity noise in the optical emission of the laser diode has also been measured. The corner frequency is shifted to a higher frequency with increasing pumping level.