直接相位调制产生线性啁啾脉冲特性研究

Research on Linear Chirped Pulse Generated by Direct Phase Modulation

直接相位调制可产生带宽可调的线性啁啾脉冲,可作为种子源用于啁啾脉冲放大系统中。对线性啁啾脉冲的产生过程以及啁啾脉冲在光纤中的传输放大过程进行了数值模拟与实验研究,实验获得了底宽为500 ps,带宽为0.69 nm的线性啁啾脉冲。在此基础上提出一种全新的产生冲击点火种子脉冲的方式,即对光脉冲的局部进行调制与压缩以获得高对比度的种子脉冲,并对其进行了实验验证。实验中将一方波脉冲经调制压缩为对比度为2∶1的阶梯脉冲,验证了该方法产生冲击点火种子脉冲的可行性。该方案为未来多种脉冲类型输出的惯性约束聚变(ICF)驱动器光纤前端系统的研制打下了研究基础。

Linear chirped pulse generated by direct phase modulation can be used in chirped- pulse amplification system, which can produce ultrashort optical pulses with high pulse energy. The process of the linear chirped pulse generation, the amplification and transmission characteristics of the modulated pulse in fiber have been numerically simulated and experimentally studied. A 500 ps pulse at 0.69 nm bandwidth linear chirped pulse has been generated in experiment. A new method of generating shock ignition seed pulse is proposed. A seed pulse with high contrast is generated by modulating and compressing part of the pulse,which is verified by expriment. A stagewise pulse with 2∶1 intensity contrast after modulating and compressing a square pulse is generated to confirm the feasibility of generating stock ignition pulse using this method. This method may be used in the front end system of intertial confinement fusion（ICF） driver in the future.