Fluorescence Detection Of Toxic Substances Based On Symmetrical Metal Cladding Waveguide

Based on the slab dielectric optical waveguide, Combined with Maxwell's equations, boundary conditions and other electromagnetic knowledge analysis the modes of the waveguide, the dispersion of the light and the distribution of the electromagnetic field in the waveguide and some other problems.Studied the properties of symmetrical metal cladding waveguide based on the fabrication of planar dielectric waveguides.The theoretical knowledge of the symmetrical metal cladding waveguide and the process of excitation of ultrahigh order guided modes in a symmetrical metal cladding waveguideis and the enhancement effect of light field in the symmetric metal clad waveguide are analyzed.The enhancement effect of light field in the symmetrical metal cladding waveguide is simulated by using FDTD software.Making sensor by using symmetrical metal cladding waveguide,Metal films deposited on the upper and lower surfaces of the symmetrical metal cladding waveguide are generally gold, silver or aluminum,the real part of the dielectric constant of the metal is a negative number with a large absolute value, so the effective refractive index of the waveguide can be a very small value,The light can be directly coupled into the waveguide cavity in the free space,a series of ultrahigh order guided modes can be excited by the light field in the symmetrical metal cladding.Only by satisfying the dispersion equation corresponding to the guided mode, the light can propagate in the waveguide cavity.Through the software simulation of symmetrical metal cladding waveguide structure absorption total reflection(ATR) spectra, when the spectral lines in the lowest means reflected light minimum and is coupled into the waveguide in the maximum light, light in the waveguide cavity in the enhancement effect of the stronges.Using FDTD software verify the field enhancement effect of the entering light in the symmetrical metal cladding waveguide,due to the limitations of computer memory,the structure of the structure is a model of the symmetrical metal cladding waveguide structure with a few tens of microns scale. When the light intensity is 1 and the incident light is at the surface of the symmetrical metal cladding waveguide with a certain wavelength, the simulation result shows that the maximum intensity of the light intensity can be enhanced 8 times. The enhancement effect of the light field based on the symmetrical metal cladding waveguide can be used to detect some material which can be excited by fluorescence., and the concentration of the detected substance can be obtained through the related calculation.Using the above method, the concentration of Luo Danming B solution was detected. The experimental results show that the method used to detects the concentration of Luo Danming B solution with a minimum of 19.3.ng/mL, far below other detection methods, and detection time is very short, the operation is very convenient. The sample's demand is also very small, avoid the problem that the sample is not enough to be detected. This method can be applied to other solutions,such as methylene blue solution and so on.The fluorescence detection method based on the symmetrical metal cladding waveguide has the advantages of low concentration limit, obvious phenomenon, short detection time, simple detection operation, low cost and small sample requirement.The detection method can be applied to the detection of most of the toxic substances which can excite fluorescence, and provides a new detection method for food detection and water quality detection, and has great significance and practicability.