Design Of Silicon-based Traveling Wave Modulator And Photodetector At 2 Micron Wavelength

Silicon-based photonic integration has recently been regarded as a solution for ultrahigh bandwidth and ultra-low power optical interconnects.High-performance electrooptic modulators and photodetectors play the role of converting electrical and optical signals.So far,both discrete devices and system integration have achieved commercialization in the communication band,but it is urgent to carry out research on optical interconnection in the 2-?m band in order to deal with the “capacity crunch”.Based on the development of silicon-based optical interconnect discrete devices and the exploration of the 2-?m window,this paper makes design analysis and performance characterization for the silicon-based modulators and photodetectors at 2 ?m.In this dissertation,we briefly describe the development trend and research status of modulators and photodetectors,and introduce the basic parameters to measure the performance.We analyze the mechanism of the carrier-depleted Mach-Zehnder modulator,and outline the working principles of silicon-based photodetectors.This dissertation designes a carrier-depleted single push-pull silicon-based modulator at 2 ?m.The simulation optimizes the structural parameters of the waveguide,improves the loss and modulation efficiency.We study the working performance of coplanar stripline and T-shaped track electrodes,and optimize the bandwidth with three factors: speed matching,impedance matching,and microwave loss.The result shows that the EE 6.4d B bandwidth is 52.2 GHz and the EO 3d B bandwidth is 21.7 GHz.According to the process conditions provided by AMF,the GDS layout was drawn.Then we build a test platform to characterize the modulator performance.The final test results show that the modulator has an insertion loss of 11 d B and a modulation efficiency of 1.6 V·cm.It can achieve OOK modulation of more than 30 Gbit/s and PAM4 modulation of 80 Gbit/s.Besides,the system bandwidth can reach 21 GHz,which is close to the simulation result.In this dissertation,we design a silicon-based photodetector at 2 ?m.We compare the difference in absorption of germanium at wavelengths of 1.55 ?m and 2 ?m,and proposes the idea of introducing defects in silicon to improve absorption.With this assumption,the responsivity of device increases to 0.15 A/W.In order to analyze the main factors affecting bandwidth,we draw the equivalent circuit model,optimize the carrier doping distribution and the length of the photodetector.The bandwidth is calculated to be32 GHz.Besides,we increase the bandwidth up to 60 GHz by adding on-chip inductance components.We draw the GDS layout according to Compound Tek's process conditions,and pass the DRC verification for tape-out.