Research On High-performance Integrated Optical Sensor Based On Novel Micro-nano Resonant Gratings

With the continuous development of micromanufacture,optical sensors are developing towards miniaturization,integration and intelligence.As a new type of micronano optical components,guided-mode resonant(GMR)grating structures have been widely used in micro-nano integrated optical sensors due to the excellent optical properties.However,a trade-off of the sensitivity(S)and the figure of merit(FOM)in this type of optical sensor is a key factor limiting its realization of high-performance optical sensing.For this problem,this thesis introduces a new micro-nano structure on the basis of the traditional micro-nano resonant grating,or constructs a new cascaded grating structure.Three integrated optical sensors based on novel micro-nano resonant gratings are proposed.The physical model of the device is established,the structural parameters are optimized,and the refractive index sensing performance of the device is improved.The main research results are as follows:1.A concave resonant grating sensor structure is proposed.Rigorous coupled wave analysis(RCWA)is used to design the device structure parameters,and the physical mechanism of the device is analyzed by using the grating eigenmode information.The concave micro-nano structure can effectively enhance the confinement ability of the grating to the local light field.By optimizing the groove depth and groove width of the concave structure,the FOM value of the grating sensor can be improved,which can theoretically reach 6562.5.2.A cascaded concave resonant grating sensor structure is proposed.The theoretical model of the output spectrum is established by combining the temporal coupled-mode theory(TCMT)and the eigenmode analysis method.By enhancing the interaction between the optical field and the detection liquid in the cascade cavity,the sensitivity of the device is improved.The structural parameters such as the grating groove depth,period and cavity length are further optimized.The theoretical sensitivity of the sensor is 401.8nm/RIU,and the FOM value is as high as 57404..3.A cascaded trapezoidal grating sensor structure is proposed.To advance the application of trapezoidal resonant grating structures in refractive index sensors,we established a theoretical model of cascaded trapezoidal resonant grating sensors using finite element algorithms and grating eigenmode information.The sensitivity of this typeof sensor can be improved by optimizing the structural parameters such as the width of the upper bottom of the trapezoid and the length of the resonant cavity.Theoretically,the sensitivity of the sensor can reach 487.5 nm/RIU,and the FOM is 9750.Compared with the cascaded concave resonant grating,the cascaded trapezoidal resonant grating sensor is easier to process.