基于太赫兹气体光子学的少周期激光脉冲载波相位的单发测量方法研究

Carrier envelope phase (CEP) is an important parameter to describe the characteristics of few-cycle laser pulses (FCLPs). To achieve single-shot CEP measurement is a both challenging and meaningful work. This project starts from the principles of terahertz (THz) gas photonics, based on the process of THz pulse influencing second-harmonic (SH) radiation from gas plasma, exploring a new method to achiev single-shot CEP measurement. From the photocurrent model, for FCLP-induced gas plasma, it will be analyzed and calculated that the characteristics of SH radiation from the plasma, and the effect of THz field on the characteristics when the plasma is irradiated by the THz pulses, and the effects of the CEP on these processes，thus providing a theoretical basis for single-shot CEP measurement. Via using a femtosecond laser oscillator/amplifier system to achive both THz pulses and FCLPs, a two-channel and four-path experimental system will be built to realize single-shot CEP measurement by means of Lissajous figures. By making some innovations on theory, principle and method, it is expected to open up a way to research the law of FCLPs interaction with gas by using the means of THz gas photonics, having a deep academic value and scientific importance. For the more, it is also expected to search a new method to realize single-shot CEP measurement, having broad application prospects.

载波相位是描述少周期激光脉冲特性的重要参数。实现载波相位的单发测量是一项既有挑战又有实际意义的工作。本项目从太赫兹气体光子学的原理出发，基于太赫兹脉冲调制气体等离子体辐射二次谐波过程，探索一种实现少周期激光脉冲载波相位单发测量的新方法。从光电流模型出发，针对少周期激光脉冲激励气体形成的等离子体，分析与计算等离子体的二次谐波辐射特性及其受太赫兹脉冲照射时特性的改变以及载波相位对这些过程的影响，为载波相位单发测量提供理论基础。利用一套飞秒激光振荡放大系统，同时获得太赫兹脉冲和少周期激光脉冲，搭建一种双通道四光路实验系统，借助利萨如图形，实现载波相位的单发测量。通过理论、原理和方法的创新，不仅可望开拓出一种以太赫兹气体光子学为手段揭示少周期激光脉冲与气体作用规律的新途径，具有深刻的学术价值和重要的科学意义，而且可望探索出一种载波相位单发测量的新方法，具有广阔的应用前景。

在本项目的资助下，围绕如何利用强场太赫兹波测量少周期脉冲载波相位的精确值这一关键科学问题，我们开展了深入的研究工作，取得了多项富有创新性的成果。其中基于光电流模型构建了少周期激光脉冲激光诱导气体等离子以及强太赫兹场调制的等离子体二倍频信号物理模型，给出了调制太赫兹波强度和少周期脉冲载波相位之间的关系。提出了一种全新双通道四光路系统少周期脉冲载波相位方法。为搭建太赫兹时域频谱和成像测试系统，利用3D打印技术制备了一系列基本太赫兹光学元件。基于测试系统还研究了一系列太赫兹频谱技术及应用、太赫兹空间光场调控技术及应用、太赫兹无损检测技术和太赫兹功能器件等问题。从研究成果来看，我们给出了一种以太赫兹气体光子学为手段揭示少周期激光脉冲与气体作用规律的新途径，具有深刻的学术价值和重要的科学意义。