| With the development of artificial intelligence,machine learning,Internet of Things,augmented reality,virtual reality and other technologies,Internet traffic continues to surge exponentially.Medium-and short-reach optical interconnects with data centers as the core are facing the expansion challenges brought about by the explosive growth of data services,and Ethernet is moving towards the 400GE/800GE era.At present,short-reach optical interconnect systems generally use PAM4 modulation format,and the single-channel transmission rate is 100Gb/s.For further scaling,traditional Intensity Modulation/Direct Detection(IM/DD)techniques will be constrained by device bandwidth,cost,dispersion,sensitivity,and power budget.Coherent optical communication technology combined with high-performance digital signal processing(DSP)technology has extremely high sensitivity,which can significantly improve the single-channel transmission capacity,and coherent technology has become a generally recognized trend in the industry.However,due to the high cost and high power consumption of traditional coherent optical communication,how to maintain the performance advantages of coherent optical communication while reducing the cost and power consumption of short-reach coherent optical interconnects has always been an urgent problem to be solved.Aiming at this pain point,this thesis simulates and analyzes the application prospects of coherent optical communication in short-reach optical interconnects in 400GE and 800GE from the perspectives of reducing device performance requirements,reducing cost,simplifying DSP complexity,and reducing power consumption,the main research work and innovation points are as follows::(1)In terms of simplifying DSP,reducing complexity,and reducing power consumption,this thesis adopts a self-homodyne coherent optical communication system.Compared with the traditional high-speed coherent system,which requires complex,high-cost tunable lasers and precise temperature control mechanisms,the self-homodyne coherent transmission system contains only one laser,which reduces the cost to a certain extent.In addition,the local oscillator and the transmitter use the same laser,and the frequency offest recovery algorithm is no longer required in the DSP algorithm,which effectively reduces the size and power consumption of future data center optical interconnect systems.(2)In terms of reducing the performance requirements of the device and reducing the cost,the device performance requirements in the 400G and 800G self-homodyne coherent optical communication systems are verified by means of simulation,and the bandwidths of the modulators and photodetectors in the system are predicted.Among them,the 400GE and 800GE systems adopt PDM-16QAM and PDM-64QAM high-order modulation formats respectively,which proves that in short-reach optical interconnect systems,wide linewidth lasers can be used instead of narrow linewidth lasers,and the bandwidth requirements for modulators and photodetectors can be reduced.In addition,under the condition of determining the laser linewidth,modulator and detector,a series of simulations were carried out on the parameters of laser power,received optical power,optical signal-to-noise ratio,IQ imbalance between transmitter and receiver,transmission distance,and maximum transmission capacity in 400G and 800G transmission systems,which verified the effectiveness of the self-homodyne transmission system.In this thesis,the application of low-complexity,low-cost,low-power coherent optical communication technology in short-reach optical interconnect systems in 400GE/800GE is verified by using low-cost optoelectronic devices under the low complexity of DSP algorithms.The application of this technology will effectively reduce the size,power consumption and transmission cost per bit of future data center optical interconnection system,providing a largecapacity and low-cost solution for the new generation of Tbit short-reach optical interconnect. |
PDF Full Text Request