Research Of Multi-impairment Monitoring Techniques Based On Cross-phase Modulation Effect

During the last decade,fiber optical communication has experienced tremendous growth mainly caused by the incessant demand for high capacity,especially for the number of users and the bandwidth consumed by each user in the internet traffic.In order to comply with the enormous bandwidth requirements,optical network have evolved towards the characteristics of diversity and intelligence.The architectures of optical networks are continuously becoming more complex,transparent and dynamic in nature,which is vulnerable to transmission impairments in the optical link.In order to provide health information of the real-time optical network,it is important to integrate effective monitoring mechanisms.In this context,the idea of optical performance monitoring(OPM)technology emerged.OPM can be competent for monitoring and compensating the impairments in the dynamic optical network and then the normal operation of the optical network will be achieved.The thesis focuses on OPM technology.Firstly,the background,recent developments and development trend of OPM technology are summarized.Then the existing OPM technologies are classified.The monitoring principle,monitoring parameters,advantages and disadvantages of mainstream technology in OPM are also discussed.At last,we propose two new OPM techniques based on cross-phase modulation(XPM)effect.In the first technique,we design the scheme by investigating the effects of impairments on optical spectrum and then use VPI Transmission Maker to simulate the proposed technique.The influence of optical impairments on the XPM-induced new optical tones are discussed in the optical domain.Then the power ratio at different frequencies in optical spectrum is used for simultaneous and independent chromatic dispersion(CD)and optical signal-to-noise ratio(OSNR)monitoring for 80 Gb/s RZ-DQPSK signal.The maximum monitoring range for CD is up to 260 ps/nm and OSNR monitoring ranges from 0 to 40 dB.Furthermore,the influence of polarization mode dispersion(PMD),input signal power and the bandwidth of the filter are considered in the chapter.The second technique is proposed based on the fact that optical impairments distort the radio frequency(RF)spectrum and the auto-correlation(AC)wave of the signal under test.In this scheme we link the both by the Weiner Khintchine theorem and retrieve the AC wave by applying an inverse Fourier transform to the RF spectrum.VPI and Matlab are used to obtain the desired XPM effect and AC wave,respectively.The simultaneous and independent CD and OSNR monitoring for 40 Gb/s RZ-OOK signal are achieved by using the combination of the difference values in the AC wave.The final monitoring range for CD is up to 50 ps/nm and OSNR monitoring ranges from 0 to 40 dB.The effect of the filter bandwidth on the monitoring performance is also analyzed and considered.The monitoring techniques proposed in this thesis present promising results and can be robust and scalable to ultra-high bit rate systems.Thus they can provide references for the future development and application of OPM technology.