Retrieval And Analysis Of High-speed Signals For The Implementation Of Linear Optical Sampling

For Internet-based information society, the multimedia services become more and more diversified and increase rapidly, and various new applications are emerging nowadays. Therefore, fiber optical telecommunication network faces great pressure and challenges. Since the advanced modulation format is helpful to enhance the spectral efficiency of coherent fiber optical transmission, due to its higher receiver sensitivity and large transmission capacity. Consequently, how to characterize and monitor high speed optical signal is critical to ensure the reliability of fiber optical transmission. Linear optical sampling is verified to be an effective technique to monitor the amplitude, polarization and phase information of high-speed optical signal. In particular, the sampling process is transferred from the electrical domain to the optical domain, which is believed to be an effective technique to characterize the quality of advanced modulation format for high-speed optical signal.In this thesis, we first explain the operation principle of linear optical sampling, and investigate the individual module of digital signal processing(DSP) algorithm. Then, we take special efforts to investigate modules of the carrier frequency offset estimation(FOE) and carrier phase recovery(CPR) algorithm. After theoretical simulation, we find that there exists a trade-off relationship between the repetition rate of optical sampling pulse and the linewidth of high speed signal under test. In particular, for the quadrature phase shift keying(QPSK) signal, when the ratio of the linewidth of signal under test with the repetition rate of the optical sampling pulse is less than 31.5 10??, the phase noise induced performance degradation can be reasonably ignored. Meanwhile, we also describe software synchronization procedures for linear optical sampling in details, and carry out the simulation for eye reconstruction algorithm.Finally, we use an optical sampling pulse with a repetition rate of 95.984 MHz, and carry out optical linear sampling to a 10.559 Gbaud BPSK and QPSK signal with a linewidth less than 100 kHz. Using the proposed algorithm, we can successfully recover the eye diagrams and constellation of the signal under test, which verifies the feasibility of the retrieval and analysis algorithm for high-speed optical signal.