基于负曲率空芯光纤的光泵太赫兹光纤激光器的理论研究

针对紧凑型、高效的光泵太赫兹激光器(OPTL)技术,设计了基于负曲率空芯光纤的长腔型光泵太赫兹光纤激光器(OPTFL)结构。该OPTFL以聚甲基戊烯(PMP)材料的空芯光纤为工作气室,填充甲醇气体作为工作物质,采用连续9P(36)支CO2激光器为泵浦源。从速率方程理论和空芯光纤的传输理论出发,分析了影响OPTFL输出特性的因素,并对负曲率空芯光纤内部微结构进行了探索,通过调整内部结构,能够实现较低损耗的单模太赫兹激光传输。结合设计的负曲率空芯光纤,对长腔型OPTFL的可行性进行了分析,理论计算表明,在最佳工作条件下,通过适当增加谐振腔长度,太赫兹激光输出功率有望达到百毫瓦量级。研究结果为高功率、高性能的OPTFL提供了一种新的方法与理论指导。

Theoretical investigation on optically pumped THz fiber laser based on negative curvature hollow-core fiber

Based on the compact and efficient optically pumped terahertz laser(OPTL) technology, an optically pumped terahertz fiber laser(OPTFL) based on a negative curvature hollow core fiber was designed. This OPTFL used a hollow-core fiber with polymethylpentene(PMP) material as operation gas chamber and was filled with methanol gas and pumped by 9P(36) continuous-wave(CW) CO₂ laser. Based on rate equations and the transmission theory in hollow core fiber, factors affecting the output characteristics of OPTFL were analyzed. By investigating inner microstructure of hollow-core fiber, a negative curvature hollow-core fiber for efficiently transmitting terahertz waves was proposed. Considering the designed negative curvature hollow-core fiber, the feasibility of long cavity OPTFL was analyzed. Theoretical calculations showed that by appropriately increasing the cavity length of the proposed OPTFL, the terahertz output power was expected to reach the order of 100 milliwatts with optimal operating conditions. The results provide a new method for the OPTFL with high power and high performance.