We present results on the lasing properties of the Bi-doped high-germania glass fibers thermally treated at different heating and cooling conditions. The absorption and luminescence spectra, the luminescence lifetime of bismuth-related active centers (BACs) formed in the Bi-doped fibers before and after treatment were measured. Analyzing the results, it was shown that the concentration of the BACs could be increased by approximately two times after treatment at certain conditions. A series of experiments regarding laser action at 1730 nm using pristine and treated Bi-doped fibers was performed. From the dependencies of the slope efficiencies of the Bi-doped fiber lasers on the length of the active fibers obtained at various cooling conditions, it was found that the optimal length \({L}\approx 20\) m of the treated active fibers required for the realization of the Bi-doped fiber lasers is two times shorter than that of the pristine fibers. In addition, the efficiency of the developed lasers being \(\approx 18\, \%\) with respect to the absorbed pump power is greater than that of the lasers based on the pristine fibers (\(\approx 10\%\) at \({L} = 20\) m), but it is lower than their maximum efficiency (\(\approx 25 \,\%\) at the optimum lengths of 45 m). From the numerical simulation of the Bi-doped fiber laser, a number of parameters needed for estimation of the native and thermally induced BAC concentrations were determined.

中文翻译：

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掺铋的玻璃化$$$ hbox {GeO} _ {2} $$ GeO2的激光特性– $$ \ hbox {SiO} _ {2} $$ SiO2掺铋玻璃纤维

我们介绍了在不同加热和冷却条件下进行热处理的Bi掺杂高锗玻璃纤维的激光性能。测量了在Bi掺杂的纤维中形成的铋相关的活性中心（BAC）的吸收和发光光谱，以及发光前后的寿命。分析结果表明，在某些条件下处理后，BAC的浓度可以增加大约两倍。使用原始和经过处理的Bi掺杂光纤进行了一系列有关1730 nm激光作用的实验。从双掺杂光纤激光器的斜率效率对在各种冷却条件下获得的活性光纤的长度的依赖性，发现最佳长度\（{L} \约20 \）实现双掺杂光纤激光器所需的经过处理的活性纤维的m短于原始纤维的m的两倍。另外，相对于吸收的泵浦功率，已开发的激光器的效率为\（\大约18 \，\％\）大于基于原始光纤的激光器的效率（\（\大约10 \％\）在\（{L} = 20 \） m时），但低于其最大效率（在最佳长度45 m时为\（\约25 \，\％\）。根据双掺杂光纤激光器的数值模拟，确定了估算自然和热诱导BAC浓度所需的许多参数。