Study Of Outer Coated Photonic Crystal Fiber Based Surface Plasmon Resonance Sensor

Photonic crystal fiber has become a very mature optical signal transmission medium because of its flexible structure design and good transmission characteristics.In recent years,photonic crystal fiber surface plasmon resonance biosensing technology combined with photonic crystal fiber and surface plasmon resonance technology has attracted the interest of many researchers.This technology has the advantages of high sensitivity and large linear range especially for the detection of small changes in the interface of biological media.It also has a wide range of applications in environmental and industrial monitoring,medical and health.As a new sensing technology,it has great research significance in sensing characteristics and applications.The characteristics of outer coated photonic crystal fiber based surface plasmon resonance sensor are studied in this paper based on the principle of easy realization,high reusability and high sensitivity,and some progress has been made in structure design and sensing performance.In this paper,the principle of surface plasmon resonance is theoretically analyzed.The detection mechanism of the combination of photonic crystal fiber and surface plasmon resonance sensing technology is studied.And the numerical calculation method of photonic crystal fiber surface plasmon resonance is discussed.Secondly,a three-core outer coated photonic crystal fiber sensor is proposed.The phase matching range is further effectively extended and the detection range of the sensor is expanded by increasing the number of core.Because the mode of multi-core photonic crystal fibers is relatively complex,the mode coupling equation of three-core photonic crystal fibers is deduced theoretically,and the coupling mode is analyzed.The sensor sensing characteristics were analyzed by finite element analysis method.The influence of various structural parameters of the sensor on the sensing characteristics was discussed in detail.The detection range and sensitivity is expanded compared with the same type of sensor.At the same time,it has the advantages of easy implementation,reusability and good toughness.Thirdly,a composite film enhanced sensor structure based on a D-shaped photonic crystal fiber is further proposed.D-shaped sensing plane is more conducive to the placement of external media,and the interaction between the light field and external media is enhanced.It is also more flexible in structure—the modulation of working band and detection range can be realized by adjusting parameters appropriately.The characteristics of the localized surface plasmon resonance sensor excited by metal nanowires are studied,which further improves the sensitivity of the sensor.This sensor has advantages in sensitivity,detection range and full width of half peak.