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The Research On 100G Silicon Optical Modulator Integrated Chips

Posted on:2019-04-29Degree:DoctorType:Dissertation
Country:ChinaCandidate:M F LiFull Text:PDF
GTID:1368330596959583Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Silicon materials are rich in sources,low in cost,good in mechanical properties and high temperature resistance.With the help of mature integrated circuit CMOS technology platform,it is easy to manufacture silicon optical chips.It can effectively solve the problem of weak manufacturing capability and insufficient technological capability of high-end optoelectronic chips in China.However,silicon is an indirect bandgap semiconductor material,which needs to solve the difficult problems of fabrication of silicon-based light sources and integration of many optical components.Silicon materials do not have linear electro-optic effect and photoelectric detection function.It is also important to solve the difficult problems of silicon modulator design and epitaxial growth of germanium-silicon materials.Additionally,the requirements of silicon optical chips of very high bandwidth,integration,performance,power consumption,reliability and low-cost of high-end optical devices are hard to meet.The development of silicon optical chips has become a very hot and difficult topic in the world for many years.In view of the above engineering and technical issues,this paper focuses on 100 G and beyond silicon integrated chip and substrate removed silicon modulator.This paper systematically studies the bandwidth limitations of the modulator and implemented a silicon optical modulator with a bandwidth of up to 60 GHz.On this basis,various silicon based optical modulators and silicon optical integrated chips are fabricated.The main innovations are as follows.(1)Aiming at the limited bandwidth of silicon optical modulator,this paper studies the high frequency characteristics of the active region and the equivalent circuit model of the modulator traveling wave electrode.Based on the above results,the bandwidth formula of the modulator is studied.Three conditions that need to be met to maximize the bandwidth are explored: lower microwave loss,perfect impedance matching,and electro-optic index matching.This paper proposes a technical solution for the substrate removed silicon optical modulator.By removing the silicon material in the substrate,higher bandwidth,more matching impedance and electro-optic index can be obtained compared to the existing modulator design.The fabricated 2mm long substrate removed silicon modular has a bandwidth of 60 GHz,which is the highest bandwidth of pure silicon waveguide type silicon optical modulator.Based on this silicon optical modulator,OOK eye diagram of 90 Gbaud/s and PAM4 eye diagram of 56 Gbaud/s are realized.It has laid a solid foundation for the industrialization of single-wavelength 100 G modulator optical chips(see M.Li et al.Photonics Research,2018,6(2): 109-116).(2)Aiming at the complexity of the design process of the modulation efficiency and insertion loss of silicon light modulators,this paper proposes a set of evaluation procedures and schemes.The numerical calculation process of carrier electrical distribution,waveguide optical mode field distribution and electro-optic overlap integral is studied.The evaluation results are basically consistent with the experimental results of the modulator chip(see X.Xiao,M.Li et al.OFC,2017.paper Tu2 H.1(Invited talk)).In view of the current problem that the single-ended modulator consumes a large power and cannot be matched with the 400 G electric chips,three differentially driven silicon optical modulators design scheme are proposed.The differential modulator can achieve a bandwidth of 30 GHz and an impedance of approximately 80 ohms with a length of 3.9 mm.The proposed three differential modulators effectively support the future 400 G optical devices(see Li miaofeng et al.patent acceptance number: 201611192997.0).(3)In view of the problem that the current optical device packaging cost accounts for 70% of the overall cost and the discrete electro-optical chip limits the overall modulator bandwidth,this paper proposes a hybrid integrated reconfigurable silicon-based single-chip optical transmitter and a monolithic integrated CWDM4 optical transmitter silicon integrated chip.These two silicon optical chips significantly reduce the packaging cost of optical devices while improving the overall transmitter performance(see N.QI,X.Xiao,Sh.Hu,M.Li et al.OFC,2016.paper Th1 F.3).(4)In view of the lower cost,higher bandwidth and longer access distance requirements of optical access networks,this paper proposes a silicon-based coherent PON solution that can achieve-45 dB sensitivity after 20 km transmission.At the same time,access costs are significantly reduced(see M.Li et al.Opt.Express,2015,23(15): 19799-19805).Aiming at the urgent demand for single-wave 100 G and four-wave 400 G optical chips in data center optical networks,this paper proposes a single-wavelength 100 G data center chip solution based on substrate removed silicon optical modulator,which realizes 10 km transmission of single-wavelength 100 G PAM4 signals.Fully meet the needs of data centers(see M.Li et al.Photonics Research,2018,6(2): 109-116).Aiming at the problems of large volume,high cost and high-power consumption of coherent long-distance transmission optical modules,a silicon-based IQ modulator optical chip design scheme is proposed.The performance of the measured module is equivalent to that of a commercial lithium niobate modulator.Based on this silicon optical IQ modulator,the single-carrier 200Gb/s transmission of 2400 kilometers is realized,and the optical chip performance is equivalent to the highest level in the world of acacia(see X.Xiao,M.Li et al.OFC,2016.paper Th4 H.5).
Keywords/Search Tags:Substrate removed, Electro-optic modulator, Silicon photonics, Traveling wave electrode, Photonics integrated circuit, IQ Modulator, CMOS Process
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