Research On Miniature Integratable Silicon Optical Sensing Chip

Sensor technology is one of the important field of information technology,plays the role of connecting the information world and real world.With the situation of pollution worsening,gas sensors and particle matter(PM)sensors are more and more popular.Meanwhile,the requirements of these sensors on miniature,integrated,and portable are increasing as the development of consumer electronics.For the miniature gas sensors design,this paper combines the silicon optical devices technology and mature theoretical support,through extensive research,and finally achieves gas sensors with high performance.For the small PM sensors design,considering the existing problems in the commercial sensors and consumer demands,two novel structures have been proposed to obtain sensors with superior performance based on light scattering theory.Finally,the superiority of these sensors is verified by simulation and experiment.The main research contents and achievements are as follows.1.A miniature gas sensor based on micro-ring resonator and ultra-low loss long waveguide is proposed in this paper.This sensor is composed of micro?ring resonator which is used as comb filter and ultra-low loss waveguide which is the optical sensitive area.This sensor is based on evanescent field absorption theory,and takes advantage of a micro-ring filter to achieve the spectrum coincide with the absorption narrow spectrum of target gas to monitor gas concentration.Compared to traditional optical gas sensor with external filter,this sensor is with smaller volume,and low cost because it can be manufactured by micro-nano processing technology to achieve mass production.Moreover,due to the working theory of the sensor is based on the spectrum technology,it makes sure that the sensor holds the high sensitivity and high selectivity.In this paper,we focus on researching the structure of optical sensitive area.Through simulating the long waveguide area and theoretical calculation,the achievable optimal EFR are 49.9%?53.9%?62.4%for SiO2?Si3N4?Si on the slot waveguide.Based on these results,for methane sensing,the resolution are 25.6ppb?23.7ppb?20.5ppb with the waveguide length of 15cm.2.A gas sensor with trace sampling volume based on closed slot waveguide(slot area is totally separated with surrounding)is proposed.Compared to the traditional open slot waveguide(slot area exposes to the surroundinf),the core sensitive area is separated from surrounding by depositing multi SiO2,and the closed slot is acted as sensitive area and gas cell.When the core layer is Si,through simulation and analysis,the achieved optimal EFR is approximately 27%with the slot width of 40nm,height of 400nm.According this result,for methane sensing,a sensor with the resolution of 44ppb is achieved with the waveguide length of 3cm,and the needed sampling gas volume is just 480?m3.The trace needed gas sample makes sure the sensor can be used in some special situation,such as monitoring the metabolite of cell or microorganism3.A PM sensor based on transparent "U" tube is proposed in this paper.In this sensor,the air flow is restricted in the tube and totally separated from other parts of the designed sensor,the advantages of the sensor includes:avoiding the performance deterioration caused by dust depositing,easy to maintain,and extending the working life of the sensor.Firstly,the availability of the sensor is verified by simulation used ray tracing method,then a linear relationship is obtained between the received scattered light and PM concentration based on Mie scattering theory.Finally,the experimental results is in accordance with the simulation results,and the resolution of the sensor is 9.8?g/m3 which is lower than the 24-hour average exposure limitation of WHO standard(25 ?g/m3).4.A PM sensor based on complicated parabolic collector(CPC)for sub-micro particles monitoring is proposed.This performance of this sensor is improved by using a CPC to collect the scattered light during ultra-large scattering angle range.In this paper,through analyzing the characteristics of scattering light distribution of particles with different size,it found that the larger of the particle size,the more scattered light propagates forward.Based on these characteristics,for sub-micro particles(such as PM 1)monitoring,a CPC with acceptance angle of 20°,output port diameter of 4.5mm,length of 9mm is proposed by numerical calculation and simulation.It manufactured by precision machining,and the resolution is 7.9?g/m3 for sub-micro particles detection with the core optical area of 11mm(height)×25mm(diameter).