Research On Optical Fiber Curvature And Strain Sensors Utilizing Two-Mode Squeezing Light Source

With the development of modern science and technology,the accuracy of optical measurement has approached the level of standard quantum limit,and the existence of quantum noise fundamentally restricts the further improvement of optical measurement accuracy.Therefore,using two-mode squeezing light source to reduce quantum noise has become a hot research topic in recent years.The main research content of this thesis is based on two-mode squeezing light source.Because quantum noise of the two-mode squeezing light source is lower than the standard quantum limits,the curvature optical fiber sensor and optical fiber strain sensor based on two-mode squeezing light source goes beyond the standard quantum limits of them.The details were as follows:1.The mechanism and properties of two-mode squeezing light source based on FWM were studied.And the pump light source,the wavelength selection ofseed light and pump light,parametric amplification and FWM effect were introduced in detail.2.A fiber optic curvature sensor based on two-mode squeezing light source was proposed and implemented.The SMF taper curvature sensors with waist cone diameters of 85.1μm,74.9μm and 67.3μm were fabricated.The bending loss of the sensors would affect the quantum correlation between the two compressed beams,and then represented the sensing of curvature.In the bending range of 0-20 m^-1,the maximum sensitivity of equilibrium detection was 0.105 d B/m^-1,and the resolution was 0.095 m^-1.Compared with the classical light source,the maximum SNR of equilibrium detection was improved by 2.84 d B.In the bending range of 0-15 m^-1,the maximum sensitivity of non-equilibrium detection was 1.153 d B/m^-1.And the resolution was 0.009 m^-1.The sensitivity and resolution of non-equilibrium detection were 10 times higher than that of equilibrium detection.3.A fiber optic strain sensor based on two-mode squeezing light source was proposed and implemented.The structure of sensor was single mode fiber-polarization maintaining fiber-single mode fiber.Then the sensing structure was placed in Sagnac interferometer to analyze the strain characteristics.The results showed that,for the balanced detection,the two-mode squeezing light source DS value of all data was less than 0 d B in the strain range of 226-357μ?.The strain sensitivity of the sensor was 0.012 d B/μ?,and the resolution was 0.833μ?.Compared with the classical light source,the maximum signal-to-noise ratio of the sensor was increased by 1.33 d B.For the non-balanced detection method,the sensitivity was0.090 d B/μ?and the resolution was 0.111μ?,which was nearly 10 times higher than the balanced detection.