Role of Er3+ ion concentration and incoherent pumping field on optical bistability in Er3+:YAG crystal

In this paper, two atomic models are proposed in an 35 nm Er3+-doped YAG crystal. The effect of Er3+ ion concentration and incoherent pumping field on optical bistability is discussed. The results for two models show that the threshold of optical bistability for some Er3+ concentration reduces and for some concentration increases. We display that the incoherent pumping field makes the behavior of optical bistability for two proposed model completely different at identical conditions for Er3+ concentration. Our results show that in the absence and presence of incoherent pumping field some Er3+ concentration can lead to maximum and minimum OB threshold. We hope that our proposed model can be suitable for optimizing and controlling the optical bistability in Er3+:YAG crystal.