实验制备了质量比为1%的Er3+掺杂75GeS2-15Ga2S3-10CsI(GGSI)硫系玻璃,测试并计算了相关光谱参数,使用多级法计算了设计的光子晶体光纤(PCF)在2.8μm的中红外信号的模场分布。在此基础上,建立了Er3+的四能级粒子数速率-光功率传输方程模型,模型综合考虑了Er3+的交叉弛豫和能量上转换,模拟得到了Er3+掺杂GGSI硫系玻璃PCF在2.8μm的中红外增益与掺杂光纤长度、泵浦功率和信号功率的变化关系。研究结果显示,Er3+掺杂GGSI硫系PCF放大器在2 750~2 950nm波段平均信号增益值超过了40dB,明显优于传统结构光纤的平均信号增益值20dB。
1wt% Er3+-doped 75GeS2-15Ga2S3-10CsI(GGSI) chalcogenide glasses are fabricated and the properties of these glasses are investigated.The mode field distribution in mid-infrared(IR) region of the designed photonic crystal fiber(PCF) is worked out by the multipole method.Based on the rate equations and light propagation equations,the numerical simulations on mid-infrared gain versus the fiber length,pump power and signal power for the Er3+-doped GGSI chalcogenide glass PCF are presented in this paper,which are compared with those of conventional fiber amplifiers.Effects of energy transfer between Er3+ levels due to cross-relaxation and cooperative up-conversion are considered here.It is shown that the average signal gain of the Er3+-doped GGSI chalcogenide glass PCF exceeds 40 dB in the region of 2 750-2 950 nm,which presents a bigger signal mid-infrared gain than conventional fibers with 20 dB.