Design And Characterization Of Photonic Crystal Devices Based On Silicon

With the improvement of circuit integration,the loss of electronic chips due to the Coulomb force between electrons is increasing,which has been difficult to meet people ’s demand for data transmission rate and transmission capacity.Photons have gradually entered people’s field of vision due to their advantages of fast transmission speed,large transmission bandwidth and weak interaction between photons.Therefore,photonic devices have many advantages in transmission capacity,transmission speed and anti-interference.Photonic crystal is a kind of material with artificial periodic dielectric structure.Photonic band gap and photonic localization are two very important characteristics of photonic crystal.Photonic crystals use photons as the carrier of information,which can flexibly control the motion behavior of photons,similar to the manipulation of electrons in semiconductor materials.Therefore,photonic crystal devices have many advantages such as small size,flexible operation and control at room temperature.The design and manufacture of photonic crystal all-optical devices with different functions will lay a solid foundation for integrated optical circuits.This paper mainly focuses on the silicon-based photonic crystal slow light devices and unidirectional transmission devices in the communication band.The main contents are as follows :Firstly,a photonic crystal microcavity structure is proposed,which has three resonant modes in the communication band of 1500～1640nm.The microcavity is periodically arranged in the horizontal direction,and the two sides are connected by W1 waveguides to form a two-dimensional square lattice photonic crystal coupled cavity waveguide structure.By adjusting the number of dielectric rods between the microcavities,the structure can achieve three slow light transmission bands in the communication band.By optimizing the shape and size of the elliptical dielectric cylinders in the cavity region and the background region,a slow light transmission with high group index of 202.46 within the bandwidth of 5.04 nm and improved normalized delay bandwidth product(NDBP)of 0.6583 can be obtained at the wavelength of 1550.05 nm.In addition,the optimized coupled cavity waveguide is very sensitive to the background materials and can be used as a slow light sensor with the wavelength sensitivity of 585 nm/RIU.Secondly,in order to realize miniaturized unidirectional transmission devices,a Fano resonant unidirectional transmission device based on one-dimensional nanobeam cavity is proposed.Single-channel unidirectional transmission is achieved at 1598 nm by using the Kerr effect of nonlinear materials,and the device has a wavelength sensitivity of 220 nm/RIU.In order to realize multi-channel unidirectional transmission,a Y-branch waveguide structure is introduced,and different types of multi-wavelength unidirectional transmission devices are designed to realize the function of simultaneous unidirectional and separate unidirectional transmission of two branches.Compared with the two-dimensional structure,the device has the advantages of small size,easy integration,excellent performance,and is sensitive to the refractive index of the background materials.Multiple functions are implemented in one device,which is very beneficial for the construction of complex all-optical integrated optical networks.