RIA: High Power Active Optical Pulse Compression

该研究启动奖项目的目标是开发一种可以与高功率激光器一起使用、不会增加幅度噪声或定时抖动、具有非常高的吞吐效率，同时提供10%至100%范围内的脉冲压缩比的光脉冲压缩器。目前的光脉冲压缩技术是基于单模光纤中的啁啾脉冲，利用自相位调制的非线性效应。虽然已经证明了高脉冲压缩比，但由于输入功率、脉冲宽度和光纤长度之间的内在权衡，该技术的应用受到限制。此外，光纤耦合损耗、激发偏振漂移以及热和声干扰都会产生幅度噪声和长期功率漂移。我们建议用高调制指数的电光相位调制器来主动地给予脉冲啁啾。这种方法的优点在于，啁啾机制不依赖于输入光脉冲的性质，而仅取决于提供给调制器的电驱动信号的质量，这可以是非常好的。我们设想脉冲压缩器将采用介质加载微波或毫米波谐振器的形式，由高稳定的合成器和清洁功率放大器驱动，随后是光栅对或棱镜色散延迟线。这项研究将致力于确定特定输入光脉冲特性所需的最佳微波腔结构和电光介质材料。这个装置应该会对超快现象的研究工作产生重大影响，因为它可以普遍应用于所有模型锁定的激光源，而与它们的功率无关。由于大尺寸、高平均功率的激光器经常被用作其他激光器或非线性变频器的泵浦源，它们的性能也将得到同样的提高。

The objective of this Research Initiation Award project is to develop an optical pulse compressor that can be used with high power lasers, does not add to amplitude noise or timing jitter, and has very high throughput efficiency while providing pulse compression ratios in the range of 10 to 100. Current optical pulse compression technology is based on chirping pulses in single mode optical fibers by the nonlinear effect of self-phase modulation. Although high pulse compression ratios have been demonstrated, the utility of the technique is limited because of inherent tradeoffs between input power, pulsewidth, and fiber length. In addition, fiber coupling losses, induced polarization wandering, and thermal and acoustical interference all combine to create amplitude noise and long term power drift. We propose to impart the chirp on the pulses actively with high modulation index electro-optic phase modulators. The advantages to this approach are that the chirping mechanism does not depend on the nature of the input optical pulse, only the quality of the electrical drive signal to the modulator, which can be extremely good. We envision the pulse compressor to take the form of dielectric loaded microwave or millimeter wave resonators driven by highly stable synthesizers and clean power amplifiers and followed by grating-pair or prism dispersive delay lines. The efforts of the research will be directed at determination the optimum microwave cavity geometries and electro-optic dielectric materials for the particular input optical pulse characteristics. This device should have a major impact on the research efforts in ultrafast phenomena since it can be universally applied to all modelocked laser sources, independent of their power. Since large frame, high average power lasers are frequently used as pump sources for other lasers or nonlinear frequency converters, their performance will be similarly enhanced.