Research On Integrated Coherent Optical Receiver Based On 120° Hybrid

In recent years,the continuous innovation of mobile communication technology and the sustained growth of data center traffic have promoted optical fiber communication systems to the goal of large capacity,ultra-high speed,low-cost,low-power consumption and miniaturization.Although the coherent optical receiver based on digital signal processing occupies a dominant position in long-distance transmission,it is not suitable for medium and short-distance transmission links that are sensitive to cost and energy consumption.In order to broaden the application range of coherent detection technology,it is imperative to carry out research on low-cost and simplified coherent optical receivers.At the same time,thanks to the vigorous development of integrated optoelectronics,micronano manufacturing processes and silicon-based heterogeneous integration technology,silicon-based integrated coherent optical receivers have become an excellent choice for medium and short-range optical communications and optical interconnection applications.This thesis focus on the simplified integrated coherent optical receiver based on the 120°optical hybrid.The main research contents are as follows:(1)The historical evolution of coherent optical communication technology is reviewed,and the research status and development trend of integrated coherent optical receivers on the silicon-based platform are summarized.The working principle of simplified coherent optical receiver based on discrete devices is analyzed,and the production process,test platform and method of silicon-based devices are introduced.(2)The 120° optical hybrid used in the simplified silicon-based coherent optical receiver is studied.With the help of commercial simulation software,the structure design and performance simulation of the optical hybrid are carried out.On this basis,the device is fabricated,and the key performance of the device is characterized through experiments.In the wavelength range of 1525~1575 nm,the measured excess loss is less than 1.5 d B,the maximum output power imbalance is about 1.0 d B,and the phase error does not exceed 7.0°.(3)A simplified coherent optical receiver chip is fabricated based on the silicon-based platform,and an experimental setup is built to test its sensitivity under different conditions.The receiver successfully received a 10 Gb/s four-level pulse amplitude modulation signal transmitted through a 25 km standard single-mode fiber without digital signal processing and dispersion compensation,the sensitivity at the hard-decision forward error correction threshold is around-9 d Bm,and the polarization dependence is about 2 d B.Furthermore,the reasons for the limited performance of the receiver are analyzed combined with the characteristics of each component and experimental conditions.