具有低频率噪声和高频率稳定度的超窄线宽激光是高精度原子光钟、基本物理常数测量和空间引力波探测等精密测量领域的核心部分。针对线宽小于亚Hz和频率稳定度优于10^-16量级的窄线宽稳频激光研制的技术难题，本项目提出基于锶原子四波混频效应实现对超窄线宽超稳激光性能精密调控的理论和实验方案。拟利用光与原子相互作用半经典理论分析四波混频效应下原子系综对光场的响应特性，研究超窄线宽超稳激光的产生机理。通过研究入射光场参量对输出光场线宽和频率稳定度的影响机制，结合激光性能调控技术及测试技术，实现对输出激光性能的精密调控，有望获得线宽达mHz量级和频率稳定度达10^-18量级的相干光源，有效避免了超窄线宽超稳激光的性能受参考腔热噪声制约的瓶颈问题。此外，研究受激拉曼增益作用下输出激光的量子噪声特性，提出有效抑制输出激光低频频率噪声的方法，为建立基于光钟的新一代时间频率计量体系奠定理论和技术基础。

Lasers with low frequency noise, high frequency stability and ultra-narrow linewidth are the key components to the development of optical atomic clocks, precision measurement of physical constants, laser interferometers for gravitational wave detection and other precision measurement fields. In view of the difficulty in the development of the lasers with a spectral width of less than sub-Hz and frequency stability of better than 10^-16 level, the theoretical/experimental scheme is proposed for precisely performance manipulation of the ultra-narrow linewidth stable laser based on four-wave mixing in strontium (Sr) atoms. Based on the semi-classical theory of light-atomic interaction, we analyze the response characteristics of atomic ensembles to the light fields under four-wave mixing effect, and investigate the mechanism for generation of ultra-narrow linewidth stable laser. By studying the dependence of the linewidth and frequency stability of the output on the parameters of incident lasers, combined with the precision control and measurement technique, it’s excepted to obtain a coherent light with a linewidth of mHz level and a frequency stability of 10^-18 level, circumventing the problem that the performance of the laser is limited by the cavity thermal noise. In addition, we investigate the quantum noise characteristic of the output laser with stimulated Raman gain, and propose the method to effectively suppress the frequency noise at low frequency, which lays a theoretical and technical foundation for the establishment of a new generation of time-frequency metrology system based on the optical clock.