李秋顺，蔡 雷，马耀宏，杨俊慧，杨 艳，孟庆军，史建国

(齐鲁工业大学(山东省科学院)，山东省科学院生物研究所 山东省生物传感器重点实验室，山东 济南 250103)

1 Introduction

引 言

Photon biosensors have developed increasingly in recent years. Especially LPFG(long period fiber grating) has attracted much attention in the field of biosensing because it has many general characteristics of optical fibers such as immunity to electromagnetic interference, non-corrosiveness, small weight, miniature size, easy compatibility with optoelectronic systems,etc. as well as unique advantages including no retroreflection, low insertion loss, wide transmitted spectrum bandwidth, high sensitivity,etc.

近年来，光子生物传感器快速发展。特别是长周期光纤光栅(long period fiber grating，LPFG)，由于其不仅具有抗电磁干扰、耐腐蚀、重量轻、体积小、易与光电系统兼容等诸多的光纤通有特点，还具有无后向反射、插入损耗低、透射光谱带宽宽、灵敏度高等独特的优点，在生物传感领域受到了广泛的关注。

LPFG is a passive optical device[1-3]which is made from periodic refractive index modulation generated by carbon dioxide laser, ultraviolet laser or femtosecond laser source axially on the fiber using the tools and technologies such as photo mask, arc discharge, distortion,etc.

长周期光纤光栅是利用二氧化碳激光、紫外激光或飞秒激光光源，并结合掩模板、电弧放电、扭曲变形等工具和技术对光纤轴向上产生周期性的折射率调制制作而成、周期一般在几百微米的一种无源光学器件[1-3]。

The transmission spectrum of LPFG is affected by cladding and surrounding environment extremely easily, so it is sensitive to the refractive index variation of environmental media[4-5]. In comparison with the extensively used SPR(surface plasma resonance) sensor, the LPFG sensor doesn't need huge prisms, rotary devices and deposited metal films, so that the LPFG sensor has very compact structure and low cost and can achieve more accurate measurement. As reported by some references[6-9], in comparison with other optical sensing devices such as Bragg grating[10-12], Fabry-Perot fiber[13], microring resonator[14-15], surface plasmon resonance[16-19], nanowire array[20-21], micro-nanofiber coupler[22],etc., LPFG has unique advantages such as higher sensitivityetc. Therefore, in recent years, many domestic and foreign researchers attempt to combine LPFG with bioactive materials for use in the detection of biological substances. Since Ashish M Vengsarkar et al. made the world's first LPFG in 1996, through over 20 years of development, LPFG has made great progress in the detection of biological substances. LPFG has been utilized extensively in the detection of many biological substances such as antigen-antibody, viruses, proteins, DNA, enzymes, nucleic acids,etc., and has become an advanced biological detection tool in the biosensing technique field. The following chapters and sections mainly describe the progress of application and study of LPFG in biological detection and look into its future development trend and prospect.

由于长周期光纤光栅的透射谱极易受包层和周围环境的影响，因而其具有对环境介质的折射率变化比较敏感的性能[4-5]。与广泛使用的表面等离子体共振传感器相比，长周期光栅传感器不需要庞大的棱镜、无需旋转部分器件及无需沉积金属薄膜，这使得长周期光栅传感器结构非常紧凑且成本低廉，测量更加精确。根据一些文献报道[6-9]，与布拉格光栅[10-12]、光纤法珀谐振器[13]、微环谐振器[14-15]、表面等离子体共振[16-19]、纳米线阵列[20,21]、微纳光纤耦合器[22]等其他光学传感器件相比，长周期光栅具有灵敏度更高的独特优势。因而，近年来，国内外许多研究人员尝试将长周期光栅与生物活性材料进行结合，用于生物物质的检测。……