中红外2.0~3.5μm波段激光在医疗、空气污染监测和军事等领域有着重要的应用前景。采用真空熔融淬冷法制备了Tm^3+/Ho^3+共掺的Ge20GasSbl0S65硫系玻璃,测试了样品的吸收光谱以及800nm激光泵浦下的荧光光谱,通过Judd-Ofelt和Mc.Cumber理论计算了Tm^3+/Ho^3+的辐射寿命、自发辐射几率和受激发射截面等光谱参数。在此基础上,研究了双掺离子之间的能量传递和Tm^3+-Ho^3+的多种跃迁过程,给出了详细的4能级系统的速率方程,并结合光功率传输方程,得出Tm^3+/Ho^3+共掺硫系玻璃光纤放大器在2tan波段的增益特性。数值模拟结果表明:Tm^3+/Ho^3+共掺硫系玻璃光纤在2μm波段的增益值达27dB,增益带宽为112nm,最佳掺杂光纤长度L=300cm,所需泵浦功率昂=200mW,可用于2μm波段宽带放大.
The mid-infrared (2-3.5 μm) emission has potential applications in medical surgery, atmosphere pollution monitoring and military. The Tm3+/Ho3+ ions doped Ge20GasSb10S65 chalcogenide glasses were prepared by a vacuumed melt-quenching method. Their refraction index, absorption spectra and emission spectra were measured. The spontaneous emission probability, radiative life- time and emission cross-section were calculated based on the Judd-Ofelt and the Mc-Cumber theories. On the basis of the energy transfer and various transitions between Tm3+ and Ho3+ ions, a four-level rate equation was proposed. The 2 tan gain properties of Tm3+/Ho3+ co-doped chalcogenide glass fiber amplifier were simulated and analyzed by the proposed and the light propagation equa- tions. The amplifier feasibility exhibits a high gain and a wide bandwidth. The simulated results show that the maximum signal gain is 27 dB, and the gain width is 122 nm.