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Establishment of dynamic measurement technique of plasma induced subsurface reaction by using wavelength-tunable femtosecond fiber laser

波长可调谐飞秒光纤激光器等离子体诱导地下反应动态测量技术的建立

基本信息

批准号：
15206012
负责人：
GOTO Toshio
金额：
$ 22.13万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

We have established the dynamic measurement technique of the plasma induced subsurface reaction by using the near-infrared wavelength tunable femtosecond fiber laser and the cavity ring-down spectroscopy.In order to realize the high sensitive measurements, we investigated the flatly or smoothly supercontinum(SC) pulse generation and the ultrashort-pulse generation of the SC pulse. On the basis of knowledge derived from the analysis, we designed the hybrid fibers which were constructed from plural fibers with different properties to realize the effective spectral broadening. A wideband of 1180-2100nm, flatly broadened, low-noise, and high-coherence SC generation has demonstrated in the three-stages hybrid fiber. Moreover, the optical pulse was effectively compresses through three-stages in the hybrid fiber. The 13-fs ultrashort-pulse generation has been demonstrated.In the cavity ring-down method that used the near-infrared wavelength tunable femtosecond pulse, high sensitivity and a high-speed detection method were indispensable. Therefore, the cavity ring-down method that used the detection method that consisted of an optical homodyne detecting technique, a differential amplification, and a digital filter was constructed. It succeeded in the measurement at the ring-down time by the cavity consisted of two high reflection mirrors that had reflectivity 99.8% or more within the range of wavelength 1200-1850nm, the femtosecond laser, and the high sensitivity detection method. The obtained ring-down time was shorter than the theory value. The cause of this difference is thought to be a divergence of the laser pulse. However, a ring-down time near the theory value can be obtained by the improvement of the coherence of the laser pulse by the optimization of the optical system etc. and the detection system.

利用近红外波长可调谐飞秒光纤激光器和腔衰荡光谱技术，建立了等离子体诱导地下反应的动态测量技术。为了实现高灵敏度的测量，我们研究了平坦或平滑的超连续（SC）脉冲产生和SC脉冲的超短脉冲产生。根据分析得出的知识，我们设计了由具有不同特性的多种光纤构成的混合光纤，以实现有效的光谱展宽。三级混合光纤中展示了 1180-2100nm 的宽带、平坦展宽、低噪声和高相干 SC 生成。此外，光脉冲在混合光纤中经过三级有效压缩。 13-fs超短脉冲的产生已经被证明。在使用近红外波长可调谐飞秒脉冲的腔衰荡方法中，高灵敏度和高速检测方法是必不可少的。因此，构建了采用光学零差检测技术、差分放大和数字滤波器组成的检测方法的腔衰荡方法。利用由两个在波长1200-1850nm范围内反射率达到99.8%以上的高反射镜组成的腔体、飞秒激光和高灵敏度检测方法，成功地测量了衰荡时间。得到的衰荡时间比理论值短。这种差异的原因被认为是激光脉冲的发散。然而，通过光学系统等和检测系统的优化来提高激光脉冲的相干性，可以获得接近理论值的衰荡时间。