Generation of ultrashort pulses in unexplored time regions and their measurement

（可见光到近红外光谱范围）我们发展了一种非共线光学参量放大（NOPA）技术，用于产生超短可见光脉冲。脉冲使我们能够观察和分析各种实时分子振动的超快动力学，其频率高达3000 cm ↑ [2]<-1>。超短脉冲具有宽带光谱，因此在整个激光脉冲的宽带光谱中可以观察到实时分子振动的超快动力学，给出了超快动力学对探测光子能量的依赖关系，并阐明了其详细动力学过程。我们研制了一种多路（128路）双锁定放大器与光谱仪相结合，用于观察超短脉冲的整个宽带谱。多通道锁相放大器可以同时测量128个探测波长，使测量时间缩短了128倍。快速测量能够增加信号 ...更多信息 信噪比（S/N）提高10倍以上或测量信号连续变化的参数时具有良好的信噪比。利用超短可见光脉冲和多通道锁相放大器，可以在宽频带内实时观察样品的信号，具有很好的时间分辨率，可以实时分辨分子的振动。（真空紫外光谱范围）我们开发了一种新颖的技术，通过利用定向分子的高次谐波产生（HHG）来产生真空紫外区的超短光脉冲。首先，我们成功地实现了在含时偏振脉冲作用下I_2分子多光子电离过程的最优控制。这意味着我们已经开发出最先进的技术来控制隧道电离，这是HHG的第一步。其次，我们在相同实验条件下观察离子产额和谐波信号的新技术使我们能够观察到电子德布罗意布罗意波在复合过程中量子干涉的第一个明确证据，即，CO_2分子排列的HHG第三步。第三，我们将偏振门技术应用于非晶体取向N_2分子的高次谐波。相反，我们的期望的基础上的椭圆度的HHG从对齐的分子，我们发现，每个谐波的光谱宽度往往是更广泛的分子轴垂直于椭圆偏振的主轴时。理论计算表明，我们的观测具有时间相关的偏振脉冲特征。这意味着，分子排列可以作为一个重要的控制参数，除了载波包络相位时，我们产生阿秒脉冲与偏振选通几个周期的脉冲。少

(Visible to near infrared spectral range)We have developed a technique of non-collinear optical parametric amplification (NOPA) to generate ultrashort visible pulses. The pulses enable us to observe and analyze ultrafast dynamics of various real-time molecular vibrations whose frequencies are up to 3000 cm^<-1>. The ultrashort pulses have broadband spectrum, therefore the ultrafast dynamics of the real-time molecular vibrations can be observed in the entire broadband spectrum of the laser pulses, which gives the dependence of the ultrafast dynamics on the probe photon energy and clarifies its detailed dynamics. We have developed a multi (128 ch) double lock-in amplifier combined with spectrometer to observe the signal in the entire broadband spectrum of the ultrashort pulses. The multi channel lock-in amplifier can simultaneously measure all of the 128 probe wavelengths, which makes the measurement time 128 times shorter than before. The quick measurement enables to increase the signal … More to noise (S/N) ratio increased more than 10 times or measure the signal continuously changing parameters in good S/N ratio. Using the ultrashort visible pulses and the multi channel lock-in amplifier, we could observe the real-time signal of the sample in broadband with a fine time resolution, which can resolve the real-time molecular vibration.(Vacuum ultraviolet spectral range)We have developed an original technique to generate ultrashort light pulses in the VUV region by using high-order harmonic generation (HHG) from aligned molecules. First, we have succeeded in the optimal control of multiphoton ionization processes in aligned I_2 molecules with time-dependent polarization pulses. This means that we have developed the most advanced technique to control tunnel ionization which is the first step of HHG. Second, our novel technique to observe both ion yields and harmonic signals under the same experimental conditions enabled us to observe the first clear evidence of quantum interference of electron de Broglie waves in the recombination process, i.e., the third step of HHG from aligned CO_2 molecules. Third, we applied the polarization gate technique to HHG from non-adiabatically aligned N_2 molecules. Contrary to our expectations based on ellipticity dependence of HHG from aligned molecules, we have found that the spectral width of each harmonic tends to be broader when the molecular axis is perpendicular to the major axis of elliptical polarization. Theoretical calculations show that our observations are characteristic of time-dependent polarization pulses. This means that molecular alignment can be used as an important control parameter in addition to the carrier envelope phase when we generate attosecond pulses with polarization gated few-cycle pulses. Less