波导式吸收腔的有效光程率研究

A Study on Effective Path Length Ratio for Waveguide Absorption Cell

波导式光学吸收腔在气体和液体浓度测量等领域有广泛的应用前景。吸收腔的有效光程与系统的灵敏度有直接的关系。提出了波导式吸收腔有效光程率的数学模型。从理论上分析了波导的内壁镀膜折射率和厚度、波导内径和弯曲以及输入光场能量分布等因素对波导式吸收腔有效光程率的影响。对提高系统灵敏度和测试系统的误差补偿提供了重要参考。计算结果与已经发表的实验数据有很好的一致性。

Optical waveguide has a promising application as absorption cell in concentration measurement of gases and liquids. The sensitivity of the measuring system is directly proportional to the effective path length （EPL） of the absorption cell. A mathematical model is proposed for the EPL of various kinds of waveguides. Theoretical analysis is made for the dependence of EPL on the waveguide parameters such as inner-coated film thickness and film refractive index, bore-diameter and bending radius, and intensity distribution of incident light. Several important results are obtained from the simulations, which provide optimizing parameters for the sensing system and algorithms for error compensation. Calculation results have shown good agreement with published measured data.