Study On Electro-optic Modulator Based On One-dimensional Photonic Crystal Nanobeam Cavity

With the development and application of new technologies such as 5G,big data,AI and cloud computing,people urgently need a communication transmission system with higher transmission rate and lower transmission cost.The optical communication system is the most ideal of the existing information transmission systems,and it is also the most likely to meet the requirements of high speed,high efficiency,economy,and miniaturization.As one of the core components in the optical communication system,the performance of the EO modulator affects the overall system.In recent years,EO modulators with excellent performance such as high modulation rate,low energy consumption,low loss,small size and easy integration have attracted more and more attention and research.At the same time,the photonic crystal structure has received eager attention from researchers because of its excellent material properties.Therefore,it is of great significance to study a new type of photonic crystal EO modulator.In this paper,two SOI-based one-dimensional Photonic Crystal Nanobeam Cavity EO modulators are proposed.They are composed of a silicon substrate,a silicon dioxide cladding,and a cladding located in the middle of the cladding.A side-coupling structure EO modulator formed by a mainline waveguide and a one-dimensional photonic crystal nanobeam cavity;and a silicon substrate,a silicon dioxide cladding layer and a incident waveguide,a download waveguide and a one-dimensional photonic crystal nanobeam cavity formed in the middle of the cladding layer The reflecting wall download type electro-optic modulator.A one-dimensional photonic crystal nanobeam cavity with a cylindrical tapered aperture is used to make the light beam better confined in the cavity,and the structural parameters of the cavity are adjusted so that the working wavelength is in the communication band.At the same time,doping is introduced on both sides of the nanobeam cavity to form a p-n junction,and the resonance wavelength of the nanobeam cavity is adjusted by applying a lower bias voltage,so as to complete the modulation using the principle of defect mode transfer.The optical and electrical structure of the designed device is simulated and calculated by Lumerica software,the structural parameters and modulation performance are optimized,and finally the structural parameters with the best performance are obtained.According to the simulation results,the two EO modulators with different optical structures proposed in this paper and their performance are compared and analyzed.The results show that the insertion loss and extinction ratio of the side-coupled EO modulator with a compact size of only 25um~2and a low modulation voltage is only 1.175V at the operating wavelength of 1550.55nm are 0.04 d B,18.2d B,respectively.The modulation speed is 8.3GHz and modulation bandwidth can reach 90GHz.The results show that the insertion loss and extinction ratio of the reflective wall download type EO modulator with a compact size of only 54um~2and a low modulation voltage is only 1.2V at the operating wavelength of 1550.01nm are 0.2d B,24d B,respectively.The modulation speed is8.7GHz and modulation bandwidth can reach 122GHz,which can be applied to integrated photonic devices and high-speed Optical communications field.