Research On Design And Characteristics Of Optical Fiber Sensor Based On Metal Nanohole Array Structure

Research on the application of optical nanohole array structures in the field of plasmonic sensing has been aroused since the extraordinary optical transmission phenomena found on optical thin metal films with sub-wavelength nanohole array structures.However,plasmonic sensor devices are generally confined to planar substrates and rely on a large optical infrastructure,so the widespread use of such optical devices is still limited.Due to its advantages of light weight,small size,low cost,high efficiency and high flexibility,the optical fiber enables the excitation of the plasma on the optical fiber to significantly simplify the optical design and reduce their dependence on some complex optical elements,so that the nano-plasma sensors have great versatility and insertability.In order to solve the problems of low sensitivity,unable angle adjustment and manufacturing difficulties,in this paper we used the template transfer method to integrate the nanohole array onto the fiber tip to fabricated the nanohole arrays structure optical fiber sensor.This method ensures the high quality and large area of periodic nanostructures fabricated on the substrate and solves the problem that the other methods easily cause the gold film to wrinkle and the nanostructures to easily detach from the substrate.By application of template transfer method,this paper designed two kinds of optical fiber nanohole array structure sensor,one is a flat face metal nanohole array fiber optic sensor,one is a beveled face metal nanohole array fiber optic sensor,and two sensors on the liquid refractive index sensing performance was tested.The test results are as follows: The signal peak in the transmission spectrum of the flat-faced metal nanohole array structure fiber sensor has a linear relationship with the change of the refractive index in the surrounding environment.The maximum sensitivity of the sensor reaches 594.45 nm/RIU and the FOM value reaches 33.12.The sensitivity and the FOM value of the beveled face metal nanohole array optical fiber sensor change regularly with the beveled angle of the fiber.The sensitivity and the FOM value reach the maximum when the fiber bevel angle is 7 °,and the sensitivity reaches 487 nm/RIU,the FOM value reaches 29,the sensor has the best sensing characteristic at this moment,and its signal peak peak is linear with the change of the refractive index of the liquid,the linear fitting degree reaches 99.12%.In this paper,Comsol Multiphysics finite element simulation software simulation and experimental curves were compared,the two fit better.In summary,this paper uses the template transfer method designed flat and beveled metal nanohole array structure of optical fiber sensor has a higher sensitivity,and the beveled face metal nanohole array optical fiber structure sensor is the first time made the angle adjustment applied to the optical fiber in the field of nanohole array structure sensors,for the development of optical fiber plasmon sensors have a positive effect.