2.8μm增益开关Er∶ZBLAN光纤激光器的数值模拟

Numerical Simulation of 2.8 μm Gain-Switched Er∶ZBLAN Fiber Laser

建立了适用于2.8μm增益开关掺Er^3+的氟化物光纤(Er∶ZBLAN)激光器的计算模型,并进行了数值模拟。模拟发现存在最佳输出镜透过率使得输出功率最大,同时耦合率也影响脉宽、峰值和脉冲形态。模拟了抽运功率对脉冲形态的影响,发现弱抽运时两个抽运周期内仅出现一个信号光脉冲,而强抽运时一个抽运周期内出现多个信号光脉冲的现象。通过模拟发现了若干未被实验报道的新现象和规律,如耦合率对输出功率、能量、脉冲形态的影响规律;抽运功率阈值附近会出现与抽运周期一致的弱信号脉冲等。研究表明,在适当耦合率和抽运功率时,2.8μm Er∶ZBLAN激光器可以实现稳定增益开关脉冲输出。

This study demonstrates a simulation model of a 2.8 μm gain-switched Er∶ZBLAN fiber laser by numerical simulation. The simulation results show that there exists an optimal transmittance of output mirror, resulting in an largest output power. The coupling efficiency has significant impacts on the pulse width, peak power, and pulse shape. Accordingly, the influence of the pump power on the pulse shape is calculated and discussed. A signal pulse appears during two pump periods with a weak pump, whereas several signal pulses appear during one pump period with a strong pump. To the best of our knowledge, calculation results, such as the influence of the coupling efficiency on the output power, pulse energy, and pulse shape and the weak signal consistent with pump period when the pump power is around the threshold, have not been reported in any experiment. This study shows that a stable gain-switched pulse output in a 2.8 μm Er∶ZBLAN fiber laser can be achieved only with appropriate coupling efficiency and pump power.