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Delivery of over 100MW-class, Nd : YAG laser pulses using hollow fibers

使用中空光纤传输超过 100MW 级的 Nd: YAG 激光脉冲

基本信息

批准号：
11650036
负责人：
MATSUURA Yuji
金额：
$ 2.24万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650036/
关键词：
Hollow fiber YAG laser Infrared fiber Optical fiber Laser machining

项目摘要

Application of Q-switched Nd : YAG lasers emitting optical pulse width of 5-10 ns is rapidly expanding its area since the laser equipment has become smaller and cheaper recently. Common silica glass fibers, however, cannot effectively transmit Q-switch pulses with a peak power more than 1 MW because of the damage at the input end and the core induced by radiation of high-energy density pulses and nonlinear effect of silica glass. Therefore, the purpose of our research is to expand the application area of Q-switched Nd : YAG lasers which is currently limited by the above fact. Our final goal is to develop a delivery system based on hollow glass fibers which deliver optical pulses with more than 100 MW of peak power.The following results were obtained in this research :(1) Design and fabrication of polymer-coated hollow fibers by using a liquid-phase fabrication method.To lower scattering losses for visible and near-infrared light, smoothness and uniformity of metal films coated on the inside of hollow fibers are improved. A silver film formed by a conventional mirror plating technique.. It was found that the smoothness and uniformity are greatly improved by keep the reaction temperature at constant by using a newly developed, water cooling system. Fibers fabricated using the new system showed low delivery losses specially for 2nd and 3rd harmonic pulses of Nd : YAG laser light.(2) Development of input couplers and gas-introducing systemTo suppress air-breakdown induced when radiating high-energy optical pulses, a input coupler which introduce inert gas to a hollow core region of fibers was designed and fabricated. This coupler enables delivery of Nd : YAG laser pulses with more than 10 MW of peak power.

近年来，随着激光设备的小型化和廉价化，发射光脉冲宽度为5 ~ 10 ns的调q Nd: YAG激光器的应用领域迅速扩大。而普通硅玻璃光纤由于高能密度脉冲的辐射和硅玻璃的非线性效应导致输入端和芯部的损伤，不能有效传输峰值功率大于1 MW的q开关脉冲。因此，我们的研究目的是扩大目前受上述限制的调q Nd: YAG激光器的应用领域。我们的最终目标是开发一种基于中空玻璃纤维的传输系统，该系统可以传输峰值功率超过100兆瓦的光脉冲。研究结果如下：(1)采用液相法设计和制备了聚合物包覆中空纤维。为了降低可见光和近红外光的散射损失，提高了中空纤维内部金属膜的光顺度和均匀性。一种由传统镜面镀技术形成的银膜。采用新研制的水冷却系统，使反应温度保持不变，大大提高了反应的平整度和均匀性。使用该系统制备的光纤具有较低的传输损耗，特别是对于Nd: YAG激光的二次和三次谐波脉冲。(2)输入耦合器和引入气体系统的发展为了抑制高能光脉冲辐射引起的空气击穿，设计并制造了一种将惰性气体引入光纤空心芯区的输入耦合器。该耦合器能够提供峰值功率超过10mw的Nd: YAG激光脉冲。