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Research On High Sensitivity Refractive Index Sensor Of Liquid Disk Microcavity Structure

Posted on:2019-01-18Degree:MasterType:Thesis
Country:ChinaCandidate:F GuoFull Text:PDF
GTID:2348330569987643Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
The sensor as the final recognition front end of intelligent hardware is the key to the development of the entire information industry.In recent years,sensors have played an increasingly important role in clinical medicine,drug development,environmental testing,and bio-safety.In particular,the development of the whispering gallery mode optical sensor is the most noticeable.Its extremely high sensitivity and miniaturized device size make it easy to implement device integration and functional integration,which has become a research hotspot in recent years.The whispering gallery mode optical sensor generally utilizes the evanescent field sensing.That is,when the light is stably transmitted in the waveguide,in addition to most of the light in the core layer,there is still a part of the light leaking into the cladding.When the refractive index of the cladding material(measured liquid)changes,the characteristics of light in the core layer will change.And the refractive index information of the measured sample will be obtained quantitatively by detecting the change in the relevant characteristics of the light field.Because the whispering gallery mode resonator has a high Q value,it can confine a large part of the light inside the microcavity,making the interaction between the light and the liquid to be measured limited.Therefore,the optical sensor of the liquid disk microcavity structure is proposed in this paper.Using the measured liquid as the core of the whispering gallery mode resonator.Light interacts with the liquid directly,which can greatly improve the sensitivity of the sensor.In this paper,the polymer is used as the optical waveguide material,and the refractive index detection of the liquid is taken as the objective.The design,fabrication and sensing test of the liquid disk microcavity optical sensor based on the cascaded cursor effect are studied.Firstly,based on the theory of optical waveguide mode,the effective refractive index method was used to calculate the single-mode transmission conditions of the rectangular waveguide.The basic characteristics of the whispering gallery mode,the coupling model of the straight waveguide and the microdisk resonator,and the principle of the multimode interference coupler are analyzed and studied.Secondly,the basic structure,principle and main performance parameters of the sensor are introduced.The vernier amplification effect is studied,and the bending loss ofresonator is calculated and analyzed.The structural model of the sensor is simulated by Opti FDTD software,and the related structural parameters are analyzed and designed.Thirdly,the process flow of optical waveguide fabrication was studied.Based on this,a mask was created based on the design parameters.Using optical waveguide fabrication techniques such as exposure and development,magnetron sputtering and inductively coupled plasma etching,a sensor sample with good sidewall smoothness was fabricated.Finally,an optical test platform is built and the sensor is tested for optical characteristics and sensing characteristics.The test results showthe sensitivity of the sensor can reach14029.91 nm/RIU,temperature coefficient is 2.21 nm/?.
Keywords/Search Tags:polymer optical waveguide, whispering gallery mode, refractive index sensing, multimode interference coupler, liquid disk microcavity
PDF Full Text Request
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