基于飞秒光学频率梳的绝对长度测量互相关法的研究

Length is one of the seven basic physical quantities, which has the important physical significance. The goal of length measurement is to expand the measurement range, improve measurement accuracy and improve the measurement speed for a long time. The traditional length measurement is difficult to break through the bottleneck of the measurement range and measurement accuracy. The emergence and application of the optical frequency comb provides a new means to achieve the long-distance high-precision measurement. In view of the mature technology of optical frequency comb in the time and frequency measurements, and the strategic application needs of high-precision length measurement in the fields of fundamental physics, laser technology, and large-scale advanced manufacturing, the project will explore the cross-correlation method of femtosecond optical frequency comb absolute length measurement. On the basis of the early theoretical and experimental research of femtosecond optical frequency comb absolute length measurement, the project combines the technologies of optical simulation. Based on the theory of dispersion pulse propagation, the discrete model of the cross-correlation signal the femtosecond optical frequency comb propagating in Michelson interferometer is proposed, the parameters of femtosecond pulse laser with absolute length measurement cross-correlation method are studied.On the basis of the cross-correlation discrete model, the continuous model of the cross-correlation functions of femtosecond optical frequency comb propagating in Michelson interferometer is developed. The cross-correlation method of absolute length measurement based on femtosecond optical frequency comb, can provide the theoretical basis for the field of advanced metrology in China, and enhance the capability of independent innovation of precision measurement technology of China.

长度是具有重要物理意义的七大基本物理量之一，长期以来长度测量追求的目标是扩大测量量程、提高测量精度和提高测量速度。传统的长度测量难以突破测量量程和测量精度的瓶颈，光学频率梳的出现与应用，为实现长距离高精度测量提供了新的突破手段。鉴于光学频率梳在时间频率测量方面已有的成熟技术及高精度长度测量在基础物理、激光技术、大规模先进制造等领域的战略应用需求，本项目将在前期飞秒光学频率梳绝对长度测量的理论和实验研究成果的基础上，结合光学仿真计算，探索飞秒光学频率梳绝对长度测量的互相关法。通过色散脉冲传播理论，提出飞秒光学频率梳引入迈克尔逊干涉仪的互相关离散模型，研究适合绝对长度测量互相关法的飞秒脉冲激光器各参数指标。在互相关离散模型的基础上，提出飞秒光学频率梳引入迈克尔逊干涉仪的互相关连续模型。基于飞秒光学频率梳的绝对长度测量互相关法为我国先进计量领域提供理论基础，提升我国精密测量技术的自主创新能力。

自项目获批以来，项目组基于飞秒光学频率梳绝对长度测量的研究积累，按照计划给出的时间节点，针对项目提出的研究内容，利用互相关法研究了飞秒脉冲激光器离散光学频率梳获得互相关函数的离散模型和连续模型。在互相关函数的离散模型中，对不同中心波长和频谱形状的脉冲序列的互相关进行仿真，发现随着传播距离的增加，互相关图案产生线性加宽和啁啾。在互相关函数的连续模型中，基于连续模型和二次近似算法研究在互相关中最亮条纹的位置，得到非线性色散深度。对于长距离，使用固定相位方法来研究互相关函数，提出使用固定相位方法的远距离测量新提议。研究了空气中诸如大气压强、温度、湿度和二氧化碳含量等环境参数的波动，对基于飞秒脉冲序列互相关的绝对长度测量的精度的影响。三年来，发表标注基金号的SCI论文9篇(含1篇在线发表)，EI论文1篇，CSCD论文5篇和中文核心论文1篇，出版教材2本，在审发明专利1项，已授权实用新型专利4项和软件著作权1项，培养出1名副教授，2名硕士研究生。总体来说，经过这三年的精心研究，计划内容基本完成。