Grating coupled surface plasmon resonance (GCSPR) sensors with wavelength modulation are widely used in many fields, but the low sensitivity holds their practical applications. Here we theoretically analyze the sensitivity limit of GCSPR sensors, provide design methods to reach the maximum sensitivity and the way to increase the sensitivity limit. The theoretical analysis shows that metal gratings with periods as large as possible should be used and the incident angle should be set close to 90^∘ in order to maximize the sensitivity for a certain detecting wavelength, moreover the sensitivity limit increases as the detecting wavelength increases. Experimentally, we prepare three gratings with periods of 314 nm, 1470 nm and 6733 nm by stripping commercial optical discs or photolithography. The measured sensitivities of the sensors based on these gratings are 319.96 nm/RIU, 1477.74 nm/RIU and 2077.26 nm/RIU, respectively. The sensitivity achieved in this article is much higher than existing ones due to the use of design method following the theoretical analysis. This work paves the way for the optimal design of GCSPR sensors.

具有波长调制的光栅耦合表面等离子体激元共振（GCSPR）传感器已广泛用于许多领域，但低灵敏度保留了其实际应用。在这里，我们从理论上分析了GCSPR传感器的灵敏度极限，提供了达到最大灵敏度的设计方法以及提高灵敏度极限的方法。理论分析表明，应使用周期尽可能大的金属光栅，入射角应设置为接近^90∘。为了使对于特定检测波长的灵敏度最大化，此外，灵敏度极限随着检测波长的增加而增加。通过实验，我们通过剥离商业光盘或光刻技术制备了三个分别为314 nm，1470 nm和6733 nm周期的光栅。基于这些光栅的传感器测得的灵敏度分别为319.96 nm / RIU，1477.74 nm / RIU和2077.26 nm / RIU。由于理论分析之后采用了设计方法，因此本文获得的灵敏度比现有方法高得多。这项工作为GCSPR传感器的优化设计铺平了道路。