Research On Function Integrated Optical Waveguide Chip And Sensing Characteristics Based On Interferometer Structure

Optical switches and optical integrated devices are widely used in the growing optical communication systems rapidly.The active integrated optical waveguide chip including optical amplifiers,optical switches and other waveguide devices are main components of the optical interconnect network received extensive attention in the field of optical communications and optical sensing.Over the past few decades,optical sensing technology has made significant progress in environmental and industrial monitoring and healthcare（eg,disease diagnosis and biomedical）applications.Integrated optical waveguide biosensors have been widely studied because of their advantages of ultra-small size,high sensitivity,no-label detection,low sample consumption,immune electro-magnetic interference,compatibility of manufacturing processes and CMOS technology for low-cost large-scale manufacturing.It can also be integrated with other devices such as light sources,detectors,and micro-fluidics units on the same chip to enable low-cost portable lab-on-a-chip applications for convenient site test applications.Based on this kind of research direction and purpose,this thesis designs several kinds of optical switch devices with different structures,and analyzes and studies based on the sensing characteristics of one of the structures.The main contents of the thesis are as follows:1.Based on the theoretical analysis of the optical waveguide mode,the characteristic equations of the asymmetrical triple-layer slab waveguide are analyzed,and the characteristic equation of the guided waveguide mode of the rectangular waveguide is deduced by using the effective refractive index method.The ridge waveguide mode is calculated and the sensing waveguide structure is calculated.The device is analyzed and the working principle of the optical waveguide to realize the sensing function is introduced,named the evanescent field principle.The waveguide mode and principle of the thermo-optic effect are described.The structure of the MZI waveguide device is introduced,and the working principle of the optical switch structure is analyzed.To lay the theoretical foundation for the subsequent design of waveguide devices.The waveguide device based on the multi-mode interference（MMI）structure is analyzed,the working mode of the optical switching device based on the MMI structure is introduced,and the working principle of the sensing function is described.2.A novel polymer dielectric-loaded surface plasmon polariton waveguide（DLSPPW）thermo-optic switch array structure was proposed.The device’s design dimensions were optimized using optical simulation software.Highly fluorinated low-loss photopolymers（FSU-8/FBPA-PC EP）and organic-inorganic graft-modified PMMA materials were used as the waveguide core and cladding polymer.Low absorption loss and excellent thermal stability of the material were measured.The transmission loss of a 4μm wide DLSPP waveguide measured by the cut-back method is 0.55 dB/cm.The insertion loss of the device is about 4.5dB.The rising and falling time of the switching device under the application of a 200 Hz square wave voltage is287 and 370μs,respectively.The driving power is 5.6 mW and the extinction ratio is approximately 13.5 d B.The multi-functional waveguide switch array with flexible structure and low loss is suitable for large-scale optic-electronic integrated circuits.The sensitive micro current phenomena obtained in the tests make DLSPPW devices more promising in implementing multi-functional integrated sensing and biomedical applications.3.A thermo-optic switching device based on polymer MZI structure with loss compensation function was designed.The erbium-doped copolymer（GETPM）material was chosen as the cladding material on the waveguide and the fluoropolymer with lower loss as the core material of the waveguide.The preparation and characteristic characterization of the main materials needed for preparing the device are introduced,such as the glass transition temperature,the weight loss temperature,the absorption spectrum and the emission spectrum characteristics of the polymers with different doping contents.The loss was reduced.At the same time,compensation for device losses can be achieved.The preparation of fluoropolymer materials,theoretical design of switching devices and process preparation were optimized,and the switching performance was analyzed and tested in detail.The optimum ratio and preparation process conditions of fluoropolymer materials were verified.Characterized the optical and thermal properties of the material.The thermo-optic coefficients of the FSU-8/FBPA-PC EP material and GETPM were measured to be-1.85×10-4℃^-1 and-1.65×10^-4℃^-1,respectively.The effective refractive index of the waveguide structure is calculated by the different refractive indices of the fluoropolymers with different doping concentrations.Optimize the size of the waveguide and the electrode and design the structure of the thermo-optic switching device.The switching device was tested and the switching response at a square wave voltage of 500 Hz was obtained.The falling and rising times were 461 and 396μs,respectively.The insertion loss is about 6dB,the extinction ratio is measured as 14dB,and the driving power is about 6.5mW.The maximum relative optical gain at 1530nm is 1.9 dB,achieving the loss compensation of the device.4.Based on the material properties,structural optimization and experimental testing of the above two part discrete optical switch devices,An active integrated optical waveguide chip based on the more simple metal cladding defined waveguide structure is proposed.The optical amplifier,optical switch and sensing area structure are optimized.The design ideas and simulation analysis of the waveguide with defined cladding of metal cladding are expounded.The waveguide mode of the structure is analyzed in detail.The Rsoft optical simulation software are used to optimize the optical switch and the straight waveguide at both ends of the multimode interference structure.The devices were prepared and tested.A detailed process for the device preparation is given and the individual parameters are precisely controlled,including preparation of the required materials,preparation conditions,experimental equipment,and so on.The part of the straight waveguide optical amplifier and the MMI thermo-optic switch were tested separately,and excellent test results were obtained.When the input optical signal power is 1mW,the maximum relative gain of the optical amplifier measured is 3.6dB.For the MMI thermo-optic waveguide switch section,the thermo-optic response was measured by applying a square-wave voltage with a frequency of 300 Hz.The rise and fall times were 511 and 341μs.The extinction ratio is approximately 20 dB and the switching power is 23.5mW.The sensing region of the waveguide with cladding defined structure was designed and tested.The sensing region size of the device was designed using the effective refractive index of the Chinese traditional medicine material of 20 mg/L as a reference point,and the device structure was optimized.The sensitivity of the device is 2×10³RIU^-1,and the resolution and detection limit are2.5×10^-4 and 1.3×10^-77 RIU,respectively.The concentration range（10-25 mg/L）of the peimine can be effectively detected within a range of 5 dB corresponding to the output optical power.