Measurement of the temperature dependence of polarization switching in gain-switched VCSELs for quantum random number generation

Abstract

We report an experimental study of the effect of the temperature of the VCSEL on the probability of excitation of a linearly polarized mode when gain-switching the device. We consider different modulation frequencies and amplitudes. We show that the probability of excitation of a linearly polarized mode significantly changes with the value of the temperature of the device. We also show that for low values of the temperature the probability of excitation saturates to a constant value as the amplitude of the modulation increases. This extends our previous results obtained at larger temperatures for which that saturation was not observed. We identify situations in which the distributions of the linearly polarized signals at a sampling time are approximately uniform. For these cases we evaluate the quality of the random numbers by using statistical test.