Study On Sensing Characteristics Of Periodic Nano-grating Waveguide Structure

As an important research direction of optical information science and technology,optical sensing technology has a very important application in the fields of industrial process,life science and environment monitoring,because of its advantages of high sensitivity,rapid detection and high reliability.Optical waveguide sensor has the advantages of simple manufacture,ease of integration,thus has been one of research hotspots in the field of optical sensing.In this paper,on the basis of the optical waveguide structure and combining grating structure,a periodic nanometer grating waveguide sensing structure is proposed,its sensing characteristics are analyzed,and its application in detecting sensor is explored.The main contents of the thesis include:First of all,the basic theories and properties of slab waveguide surface plasmon polaritons and surface plasmon waveguide are introduced.From the theories the electromagnetic field mode and transmission characteristics of the waveguide are studied,which provides some theoretical basis for the following design and research of the sensing structures.Secondly,combining with the grating model and using the waveguide layer as a sensing layer,a periodic nanometer dielectric grating waveguide sensing structure is designed,and the transmission process of the electromagnetic wave is simply described.Through the slab waveguide theory the relationship between the refractive index of the sensing layer and the resonance wavelength is established.The influence of the grating structure parameters on the resonant mode of the sensing structure and the sensing characteristics are also analyzed in detail.Finally,using the enhanced local characteristics of the surface plasma wave and based on the sensing structure of periodic nanometer grating waveguide,a periodic nanometer metal grating waveguide structure is proposed.The transmission process of the electromagnetic wave is also described.And the relationship between the refractive index of the sensing layer and the resonant wavelength is established.Then,the thickness of the metal layer is optimized and the sensitivity of the sensor is calculated.The sensitivity of the sensor is found to be better than that of the periodic nanometer dielectric grating waveguide sensing structure.Finally,the two sensor structures are applied to the detection of water content in heavy oil.The latter shows a higher sensitivity.So it can detect the substances with small molecules and low concentration and apply to the fields of the optical integration and sensors.