We report a method to detect chiral enantiomers via an optical thin-film coated long-period fibre grating sensor. To simulate such circularly layered structure containing magneto-electric coupling enantiomers, the theory for wave propagation in lossy thin-film coated fibres expanded by separating cladding modes into left and right circular polarization. The applicable conditions and solving process of complex effective refractive indices for the cladding modes are discussed. The behaviours of the complex refractive index of the lossy sensing film, optical activity and refractive index of enantiomers, mode and period of the grating on sensing characteristics of the sensor are theoretically clarified. By simultaneously observing variations of dual resonance wavelengths and minimum transmissions of the sensor, the refractive index-induced and chirality-induced changes can be distinguished. This work may provide sufficient guidelines to explore the design and application of long-period fibre grating chirality sensors in industrial, environmental, and biochemical sensing.

我们报告了一种通过光学薄膜涂层长周期纤维光栅传感器检测手性对映体的方法。为了模拟这种包含磁电耦合对映体的圆形层状结构，通过将包层模式分为左右圆极化，扩展了在有损薄膜包覆光纤中波传播的理论。讨论了复合有效折射率在包层模式下的适用条件和求解过程。从理论上阐明了有损传感膜的复折射率，对映体的光学活性和折射率，光栅的模式和周期对传感器的传感特性的影响。通过同时观察双共振波长的变化和传感器的最小透射率，可以区分折射率引起的变化和手性引起的变化。这项工作可能会提供足够的指导方针，以探索长周期光纤光栅手性传感器在工业，环境和生化传感中的设计和应用。