提出了一种可抑制角漂移的表面等离子体传感器结构，并结合相位测量设计了相应的气体折射率测量系统。分析表明激光入射角、金膜厚度以及反射光p、s分量的相位差与气体折射率之间的固有非线性是影响相位响应度与折射率测量精度的主要因素。计算表明所提出的自适应结构将角漂移引起的误差降低了一个数量级并很大程度提高了测量灵敏度。同时分析设计了金膜厚度参数，并评估了反射光p、s分量的相位差与气体折射率之间固有非线性带来的误差。应用于空气折射率的测量比对实验显示其测量精度达到了10-6量级。

A surface plasmon resonance (SPR) sensor with self-adaptive structure for angle shift is presented. Combined with phase detection, a measurement system for the gas refractive index is designed. The theoretical analyses indicate that the factors which affect the response of phase detection and measurement precision are the incident angle of the laser beam, the thickness of the gold film and the nonlinearity between the phase difference of p and s polarization components of the reflected light and the refractive index of gas. The application of the self-adaptive SPR sensor reduces the measurement error by one-order of magnitude and greatly improves the sensitivity. The thickness of the gold film is designed and the error which results from the nonlinearity between the phase difference of p and s polarization components of the reflected light is evaluated as well. The comparison experiments of measuring the refractive index of air show that the accuracy of the gas refractive index measurement system reaches 10-6 order.