Study On Solution Concentration Sensing Characteristics Of Optical Waveguide Ring Resonator

Nowadays,with the rapid development of information technology,sensor technology is developing rapidly.It has become one of the three pillars of information industry technology and has the same status as computer technology and communication technology.Sensor measurement of solution concentration has been widely used in industrial production,agricultural medicine,daily life and other fields.Therefore,the existing sensors can not meet people's needs,and need to invest a lot of technology to develop products with lower cost,smaller structure and higher efficiency.In this paper,an optical waveguide ring resonator structure is designed based on evanescent wave sensing principle.The sensing structure for measuring solution concentration is fabricated by microelectronic fabrication process.Optical waveguide ring resonator has compact structure,convenient processing,flexible design and high quality factor.Applying this structure to the sensing measurement of solution concentration can realize various advantages of optical sensor and obtain high sensing sensitivity.In this paper,silicon dioxide doped germanium is used as the core material of optical waveguide.And sodium chloride and ethanol solution are used as the targets to be measured.The design and fabrication of a solution concentration sensor for an optical waveguide ring resonator and its sensing performance are studied.Firstly,the mode field and electromagnetic field theory of optical waveguide are analyzed.The basic structure and related theory of ring resonator are introduced.And the relationship between the characteristic index and the performance parameters of the resonator and the transmission matrix of the resonator are analyzed.Secondly,the optical waveguide ring resonator is modeled and simulated.Design and optimize the structure parameters of composite waveguide.The sensing theory of optical waveguide ring resonator is analyzed.The waveguide structure was modeled by Comsol finite element simulation software to simulate the concentration test of solution.Thirdly,according to the main parameters of the optical waveguide ring resonator obtained by modeling and simulation,we design and fabricate photolithographic mask through external co-processing.In the fabrication of sensor structure,we need to choose photolithographic and dry etching methods.Finally,the optical transmission performance of the optical waveguide ring resonator sensor structure was tested experimentally.And five different concentrations of sodium chloride solution and alcohol solution were tested.The free spectrum range of the structure spectrum is about 4.54 nm.The quality factor Q is about 3.24×10~3.The sensitivity of the structure to the concentration of sodium chloride solution and alcohol solution is about 83.5pm/%and 24.78 pm/%,respectively.