SBIR Phase II: Simple Device for Measuring Nanosecond Laser Pulses

这个小企业创新研究计划第二阶段项目提出开发一种简单，单次拍摄，廉价，完整的激光脉冲测量设备，用于~100皮秒到~10纳秒脉冲。长脉冲（10纳秒）很容易测量，最近开发的技术可以完全测量超短脉冲（10皮秒）。但是，中等长度，~1纳秒，脉冲仍然只是部分，粗略和昂贵的测量，因此通常仍然是复杂和不稳定的。这是不幸的，因为大多数激光脉冲都在这个中间范围内。所提出的测量装置是基于频率分辨光学门控（FROG），一个非常成功的技术，用于测量完整的强度和相位与时间的飞秒脉冲。将FROG扩展到更长的脉冲的主要挑战是在单个脉冲上产生许多纳秒的延迟范围，这是目前普遍未解决的问题。所提出的创新通过将输入脉冲倾斜显著的~89.99°而不使其在时间上失真来解决该问题。因此，一个约1厘米宽的光束的一边领先另一边超过一米。拟议的纳秒FROG可以完全测量甚至复杂的脉冲，成本不到目前用于部分测量此类脉冲的高带宽示波器的十分之一。该项目更广泛的影响/商业潜力来自于这样一个事实，即大多数脉冲激光器，从固态激光器到光纤激光器，发射的脉冲约为纳秒长。它们是世界上最不稳定的激光器，但它们有数十亿美元的应用，从材料加工到距离测量，从遥感到医疗，军事和科学用途。有了这个设备，纳秒激光器将最终拥有一个以前无法使用的设备来监测它们的性能，并在昂贵的材料被破坏或患者受到伤害之前诊断出问题。这对于组合来自多个光纤激光器的脉冲也是必不可少的，通常被认为是开发紧凑和方便的高功率脉冲激光器的下一个重要步骤。最后，使用该设备，激光工程师一般将能够更好地提高纳秒激光脉冲的质量，从而大大有利于所有脉冲激光应用。如果在类似的完整脉冲测量技术被引入之后发生的更短脉冲激光器的惊人进展有任何迹象，那么这种用于测量纳秒脉冲的廉价和简单的设备应该在产生更清洁，更稳定的纳秒脉冲方面产生巨大的差异，从而在使用这种激光器的许多领域中产生巨大的差异。

This Small Business Innovation Research Program Phase II project proposes to develop a simple, single-shot, inexpensive, and complete laser-pulse measurement device for ~100-picosecond to ~10-nanosecond pulses. Long (10 nanosecond) pulses are easily measured, and recently developed techniques completely measure ultrashort pulses (10 picosecond). But intermediate-length, ~1-nanosecond, pulses remain only partially, roughly, and expensively measurable, and so generally remain complex and unstable. This is unfortunate because most laser pulses are in this intermediate range. The proposed measurement device is based on frequency-resolved optical gating (FROG), a very successful technique for measuring the complete intensity and phase vs. time of femtosecond pulses. The main challenge in extending FROG to much longer pulses is the generation of a many-nanosecond delay range on a single pulse-currently an unsolved problem in general. The proposed innovation solves it by tilting the input pulse by a remarkable ~89.99° without distorting it in time. As a result, one side of a ~1cm-wide beam precedes the other by over a meter. The proposed nanosecond FROG can completely measure even complex pulses and will cost less than one tenth as much as the high-bandwidth oscilloscopes currently used to only partially measure such pulses. The broader impact/commercial potential of this project follows from the fact that most pulsed lasers, from solid-state lasers to fiber lasers, emit pulses about a nanosecond long. They are the least stable lasers in the world, yet they have billions of dollars of applications, from materials processing to distance measurements to remote sensing to medical, military, and scientific uses. With the proposed device, nanosecond lasers will finally have a previously unavailable device to monitor their performance and to diagnose problems before expensive materials are ruined or patients are harmed. It will also be essential for combining pulses from multiple fiber lasers, generally regarded as the next important step in the development of compact and convenient high-power pulsed lasers. Finally, using this device, laser engineers in general will be better able to improve the quality of nanosecond laser pulses, thus greatly benefitting all pulsed-laser applications. If the spectacular progress in much-shorter-pulse lasers that occurred after analogous complete pulse-measurement technology was introduced there is any indication, such an inexpensive and simple device for measuring nanosecond pulses should make a huge difference in the generation of cleaner, more stable nanosecond pulses and consequently in the many fields that use such lasers.