大气颗粒物多参数激光自混合传感的数值模拟与特性分析

基于颗粒物米氏散射特性、激光自混合三镜腔理论和激光器稳态条件,推导出在大气颗粒物光反馈下激光器频率、功率、线宽的理论表达式,建立了大气颗粒物光反馈下的激光自混合理论模型。同时,数值模拟和分析了大气颗粒物物理参数对激光自混合干涉信号的影响。结果表明,在一定粒径范围内,激光自混合反馈强度随大气颗粒物粒径增大先增大后减小,且反馈强度峰值出现的位置随颗粒物折射率实部的增大、虚部的减小向粒径较大处移动;自混合系统的外腔长度影响自混合干涉信号的波动深度,激光器输出光信号的幅值随外腔长度增大呈指数衰减;自混合干涉信号波动频率与大气颗粒物运动速度呈线性关系。分析结果对基于激光自混合效应的大气颗粒物多物理参数传感具有重要作用。

Numerical Simulation and Characteristics Analysis of Laser Self-Mixing Interference Measurement of Atmospheric Particle Parameters

The theoretical expressions describing the self-mixing interference laser frequency, output power, and linewidth under the weak feedback of atmospheric particles are deduced based on the Mie scattering theory, the three-mirror theory and the steady-state equations of laser. The theory model of self-mixing effect feedback from atmospheric particles is established. And the relationship between the self-mixing signals and the physical parameters of atmospheric particles is analyzed in detail. The result shows that in a certain particle size range, the laser self-mixing signal intensity increases with the particle size and then decreases. With the increase of the real part and decrease of the imaginary part in atmospheric particle complex refractive index, the location of the external feedback strength peak value gradually moves to larger particle size. The amplitude of self-mixing signals is exponential decay with the increase of the external feedback cavity; the fluctuation frequency of the laser intensity is linearly related to the velocity of atmospheric particles. These conclusions offer a theoretical guidance to study optical sensing applications of atmospheric particles physical parameters by using the laser self-mixing technology.