1.54 μm lasing from silicon in presence of Erbium doping

Lasing at 1.54 mum from Erbium doped silicon has been studied. A model has been developed for the mechanism of energy transfer to erbium by electron-hole recombination through erbium sites. Emission rates of erbium through intra 4f shell transitions by spontaneous and stimulated processes have been equated with the excitation rates. Detailed analysis on rate equations show the feasibility of achieving population inversion and lasing threshold for incorporation of 10¹⁹ cm^-3 of optically active erbium sites. Low threshold current densities of the order of A/cm² has been estimated for optimized lasing conditions. Linear increase of laser output with excitation current has been simulated. Modulation compatibility of the erbium doped silicon lasing system has been studied by introducing small signal components at various operating conditions. It was found that direct modulation of the 1.54 mum erbium emission with frequencies up to Gega hertz level is feasible. The 3 dB bandwidth of laser response was found to be a strong function of the power output. Rate equations of laser operation were also solved for large signal conditions. Turn-on delays of the order of tens of nanoseconds have been estimated.