The Application Study On Highly Sensitive Optical Fiber Interference Sensor

In recent years,optical fiber sensors have become the focus of research by domestic and foreign experts and scholars due to their high sensitivity,simple manufacturing techniques,small size and anti-electromagnetic interference,etc.At present,optical fiber sensors have been widely used in national defense,military,biomedical,environmental monitoring and other fields.How to detect the parameters to be tested more quickly and intuitively and how to improve the detection sensitivity are the difficulties in current research.In this paper,the principle of a typical interferometer is used to fabricate the structure of the optical fiber interferometer by welding and precision cutting different kinds of optical fibers,and then the pressure and solution concentration of the prepared sensor structure are tested respectively.The main contents are as follows:First of all,we have designed a kind of optical fiber fabry-perot gas pressure sensor with vernier effect,the sensor consists of a single mode fiber,hollow core fiber and photonic crystal fiber by welding each other,through the theory of optics vernier effect and sensitization mechanism analysis concluded that the two fabry-perot interference cavity cascade and according to the ratio of the optical path is close to 1:1 can achieve the effect.In the experiment,the length of the hollow core fiber we cut was about 100 ?m,and the length of the photonic crystal fiber was about 30?m.The reflection spectrum of this structure showed mixed interference spectrum superimposed by two interference patterns,and the low envelope of the interference spectrum was an obvious curve.The pressure test results show that the sensitivity of the fiber optic FP pressure sensor is as high as 20.286nm/mpa,which is several times higher than that of the fiber optic pressure sensor reported in recent years.Secondly,we prepared a fiber optic mach-zehnder interferometer which can rapidly detect the concentration of bovine serum albumin solution.This sensor is only prepared by manual dislocation welding of microfiber and single-mode fiber.The light in the air cavity of microfiber changes the refractive index of the medium due to the change in the concentration of bovine serum protein solution(0.1-0.6mg/mL),which finally affects the optical path difference and realizes the sensing principle.The test results in bovine serum protein solution showed that this biosensor was very sensitive to the solution concentration,reaching-22.424nm/(mg/mL),which laid a good foundation for the fiber optic sensor to enter the field of biomedicine in the future,and to realize rapid and highly sensitive detection of biochemical substances.