Silicon Based Photodetector And Its Application

Among the big data era,the explosive growth of the data makes great challenge to the communication system.The optical fiber based communication technology is widely used in the long-distance communication networks to realize ultra-large capacity and ultra-high speed transmission.However,in different network notes,integrated and compact optical module now is the trend.On the other hand,the traditional electrical interconnect shows its disadvantages in big data center and high performance computer due to its huge power consumption and low capacity.On the contrast,the optical interconnect,with low latency,low power and large capacity is the best alternative choice.The silicon photonics(Si Ps)based optical interconnect is greatly preferred furthermore.Silicon based photodetector is one the key component in Si Ps,and is widely used.There are two ways to realize high performance silicon based photodetectors,one is rely on the CMOS compatible germanium material,the other is by integrating ?-? devices onto silicon substrate.This thesis mainly introduced some works about the silicon based photodetector.The high speed and high power silicon based photodetectors are demonstrated after thoroughly analyzing its behind physical mechanism.In addition,some photonics integrated circuits(PICs)with multifunction are demonstrated based on the proposed high performance silicon based photodetectors.The works in this thesis can be summarized as below,(1)Two methods to improve the bandwidth of silicon-germanium based photodetector(Si Ge PD)using gain peaking technology are proposed.One is by optimizing the on chip spiral inductor forming on chip gain peaking Si Ge PD.The other is by introducing a piece of wire with some inductance into the Si Ge PD forming off chip gain peaking SiGe PD.The high speed SiGe PD will be applied in the rest works.(2)A high power and high speed Si Ge PD based on parallel dual Ge regions is proposed.The space charge effect is greatly reduced by optimizing the optical structure of the Ge region and adopting double sides illumination structure.The total capacity of the device is compensated by the total parasitic resistance due to the parallel dual Ge regions,thus the bandwidth of the proposed device is maintained.The measured results validate the superior performance of the device.(3)The integration of high-speed GaAs PD and SiPs substrate by the means of transfer printing is proposed.The design method of the high speed Ga As PD and the transfer printing based processing are detailedly described.The measured high-speed results validate its superior performance and shown its potential application in chip scale optical interconnect.Besides,the transfer printing technique is firstly applied in the integration of Ga As PD with transimpedance amplifiers(TIA),and the measured results shown its feasibility.(4)The photonics integrated circuits(PICs)based on high performance Si Ge PDs are proposed,which contains a dual-detector optical receiver for PDM signals direct detection,two kinds of on chip large capacity PICs and an on chip monitor.The optical receiver is composed of a two dimensional(2D)grating coupler and two separated Ge regions based Si Ge PDs with double sides illumination and can be used in the short distance communication system where direct detection is greatly needed.The on chip large capacity PIC,which was realized by monolithically integrating the Si Ge PDs,silicon micro-ring modulators(MRMs),silicon micro-ring(MRR)based multiplexer/de-multiplexer,polarization rotated splitter(PRS)based multiplexer/de-multiplexer and other passive components.The proposed PICs can satisfy the capacity requirement of future chip scale optical interconnect.The on chip monitor is based on high performance Si Ge PD and MRR based mode converter.It can realize harmless and flexible monitoring of the on chip transmitted multidimensional signal.The monitoring of on chip transmitted WDM-MDM signals is experimentally validated.