Research Of Polymer-based Optical Switch Devices And Integrated Technology

With the rapid development of communication technology,human society has got into the new information age.The following 5th generation wireless systems will drive a huge industrial transformation of many industries.It will bring considerable innovation in medical,education,smart homes,intelligent cities and other fields.The rapid development of communication technology is inevitably accompanied by higher demand for optical networks.As an important component of optical network,optical switch and its performance improvement technology will become an important development direction in the field of optical communication.In order to achieve the integrated optical switch chip performance such as low delay,low power consumption,high integration,high reliability with simple technology,the research on optical switch and its integration technology is very important.In this thesis,the thermo-optic(TO)switch and electro-optic(EO)switch devices based on the organic polymer materials has been studied.Considering the optical and thermal properties of low loss polymers,nonlinear optical polymers and inorganic materials,several optical switch devices are designed,fabricated and tested.The main work of this paper is summarized as follows:1.Firstly,based on the theory of planar optical waveguide,the effective refractive index calculation methods of several structural waveguides are briefly introduced.For the MZI(Mach-Zehnder Interferometer)optical switch device studied in this paper,the MZI waveguide structure and the working principle of the optical switch based on this structure are introduced.The principle of MZI waveguide structure and the thermo-optic effect and electro-optic effect of the materials are introduced at the same time.2.An organic/inorganic hybrid waveguide thermo-optical switch and its integrated fabrication process are proposed.The polymer /Si O2 hybrid waveguide structure and air trench structure are introduced to shorten the response time and reduce the power-consumption of the device.According to the properties of the selected materials,the single-mode transmission conditions of the waveguide are calculated.According to the optical and thermal characteristics of the materials,the influence of the introduction of the air trench structure on the optical field distribution and thermal field distribution of the waveguide has been analyzed.Based on the simulation results,the optimized design of the waveguide and electrode structures is completed.Aiming at the problem of increased process cost caused by the introduction of the air trench,a integrated process has been proposed.This article uses an integrated process to complete the device preparation.The prepared devices are tested for optical performance and dynamic response.The power consumption of the device is about 5.2 m W,and the switch rise time and fall time are 192.2 and 201.1 μs,respectively.Compared with the reported TO switchs based on different material systems,it can be seen that the performance of the TO switch device has been improved in terms of the response time and power consumption.The response time and power consumption of the device are improved Through introducing this device structure and preparation process can also simplify the manufacturing process of the TO switch and reduce the production cost of the device.3.A non-linear polymer material,MS-TCF / P(MMA-GMA),has been synthesized.The film-forming properties and the optical and thermal properties of the material has been characterized.In face of the problem of non-linear polymer materials intrinsic optical absorbing,the traditional polymer EO switch structure has been adjusted.A novel EO switch based on a non-linear polymer cladding layer and a low-loss polymer core is proposed.In single-mode transmission conditions,the core waveguide size is determined by calculating the optical field distribution in the waveguide cladding.According to the designed size,the optical field distribution of the waveguide cross section,the electric field distribution inside the dielectric layer,and the beam transmission in the device are simulated separately.A full wet etching process is used to complete the device fabrication.The insertion loss of the prepared EO switch is about 10.2 d B,and the switch rise time and fall time are 55.58 and 57.98 ns,respectively.Compared with similar structures reported previously,by adjusting the waveguide structure,it is possible to effectively reduce the insertion loss of the polymer EO device on the basis of the realization of the switching function,which has important application prospects in large-scale integrated photonic chips containing EO modulation unit devices.4.Traditional EO devices based on a non-linear polymer core layer are not conducive to the preparation of integrated devices due to the material mismatch of the core layer and the optical absorption.In view of this situation,combined with the previous research work on thermo optic switch and electro-optic switch,a three-dimensional integrated optical switching device based on a nonlinear polymer cladding waveguide is proposed in this paper.The device consists of a vertical coupler and a non-linear polymer-clad MZI waveguide.The vertical coupler can realize the optical signal interconnection between the upper and lower waveguides,and it can be controlled by the TO effect.By using a non-linear polymer as the upper cladding material,high-speed switching or modulation of the signal can be achieved.According to the optical characteristics of the selected materials,the structural parameters of the device are optimized.A CMOS compatible process is used to complete the device fabrication.The prepared device can realize the optical signal arbitrary switching between the upper and lower waveguides and the high-speed modulation with a response time of about 10 ns.This device realizes the function integration of controllable three-dimensional optical interconnection and high-speed modulation.This method provides a feasible solution for the application of polymer EO devices in three-dimensional integrated devices,which is beneficial to the expand the application of electro-optical devices in three-dimensional integrated photonic chips.