Investigation of optical amplification in Si-Nanocrystal-Er doped optical fibers

Abstract

In this article the details of Erbium doped Fiber Amplifier (EDFA) in presence of Silicon nanocrystal (Si-Nc) is investigated. In this analysis Si-Nc and Er ions in matrix of fiber are assumed two and five levels respectively. For this structure rate equation for transient and steady state analysis is considered. The range of Er (+3) concentration and pump intensity at 488 nm are considered (10 17 − 10 21 )1/cm 3 and (10 17 − 10 23 ) photon/cm 2 · sec respectively in this paper. Based on numerical simulation of this problem we observed that with increasing of concentration of the Si-Nc the fiber length for given optical gain is decreased. For example in the case of 40 dB optical gain, we calculated fiber length to be 1.1 × 10 5 cm without Si-Nc and 5 × 10 2 cm for σCCa =1 × 10 −17 cm 2 (confined carrier absorption cross-section) and 5 cm for σCCa =1 × 10 −19 cm 2 respectively. Our simulations show that for second level with increasing pump intensity the population rise and fall times are decreased. But, for third level the population rise time is decreased and fall time is depends to level of Er ion interactions. We observed that with increasing Er ions optical net gain is increased and finally has a maximum. After this special value of Er ions because of increasing in interaction between ions the net gain finally begin to decrease. In this analysis we let to Er ions have inhomogeneous distribution. Also, we observed that in this case with increasing of the distribution peak, the net gain is increased, interaction between ions is increased, the coupling coefficient to the Si-Ncs is increased and losses due to Si-Ncs are decreased. Finally effect of Kexiton (maximum number of exciton in single Si-Nc) on amplification process is considered and we observed that in the case of Kexiton = 2 the optical gain considerably and introduced losses due to Si-Nc are increased.