Slow Light Devices Based On One-Dimensional Photonic Crystal Silicon Waveguide

With the development of technology,the demand for high-speed communication is growing.The optics communications receive more and more attentions because it is an important way to realize this demand.As one of the fundamental components that links the information technology and optics,optical memory devices play an extremely important and irreplaceable role.Optical storage technology can further increase the bandwidth of the optical communication system which would greatly enhance the computing ability of computers.However,compared with the storage part of electronic technology,the optical storage technology is quite immature and faces many technical problems.And to satisfy commertial applications,the optical technology has higher requirements for device integration,high-speed communication,low loss,small device size and so on.Among the numerous solutions,silicon-based photonic crystal devices are compatible with traditional CMOS technology and are easier to be integrated.Compared with other slow-light devices,their potential of wide bandwidth makes them more adaptive to the future high-speed optical communication technology.Nevertheless,conventional planar photonic crystal waveguides have many problems.For example,they are difficult to be fabricated because of their multi-hole-row structure,long processing time due to the requirement of high precision small minimum feature size and large loss due to the roughness of the vertical section.Compared with conventional two-dimensional planar photonic crystal waveguides,one-dimensional photonic crystal waveguides significantly reduces the device size,and their simple structures reduce the processing difficulties.In this paper,the optical devices based on the simple structure of one-dimensional photonic crystal waveguides are studied as follows:(1)The research background and present status of silicon-based slow-light technology are investigated,and the process of development of silicon-based micro-ring structure slow-light devices and silicon-based photonic crystal waveguides devices is depicted.The theory of light propagation in photonic crystal waveguides and the calculation method are also introduced.(2)A new structure of one-dimensional photonic crystal waveguide is proposed.By introducing multi-teeth structure into the one-dimensional periodic grating waveguide,the defect effect is obtained.And the "group index-wavelength" curve which has a large bandwidth is found.The fishbone-like one-dimensional grating waveguide has a bandwidth of more than 10 nm when the group refractive index is 13.In order to compensate the coupling loss,a step taper is designed to improve the coupling efficiency from less than 20%to more than 60%.The waveguide is fabricated and tested to verify the results of theoretical simulation.Based on the calculation results of Fabry-Perot theory,the bandwidth of the device is more than 10 nm when the group index is about 12.In order to study the tunability of slow-light waveguides and further increase the bandwidth,a two-dimensional material,graphene,is introduced to the device.The graphene is laid on the top of the waveguide to test the thermal modulation ability.(3)A novel structure of hole-ring resonator based on one-dimensional photonic crystal is proposed to realize the transmission spectrum of EIT-like transparency.Compared with the traditional couple-ring structure to achieve electromagnetic induced transparency,the single ring structure greatly reduces the size of the device.Furthermore,at the wavelength of about 1550 nm,the structure can form multiple transparency windows and can behave as a refractive index sensor with high resolution.The figure of merit can reach larger than 530 because of the enhancement of the interaction between light and matter of the hole and slow light effect,showing excellent sensing performance.