Translator Disclaimer
11 November 2008 Monitoring techniques for phase and OSNR of DPSK/DQPSK signals
Author Affiliations +
Proceedings Volume 7136, Optical Transmission, Switching, and Subsystems VI; 71360U (2008)
Event: Asia-Pacific Optical Communications, 2008, Hangzhou, China
We review our recent achievements in the optical performance monitoring techniques such as the optical phasor monitor and optical signal-to-noise ratio (OSNR) monitor developed for differential phase-shift-keyed (DPSK) and quaternary PSK (DQPSK) signals. The optical phasor monitor is a tool that can measure the in-phase and quadrature components of the optical field of the phase-modulated signal and display the measured results on the complex plane as a phasor. We implement such a phasor monitor by using an adjustment-free differential-phase demodulator composed of a 120-degree optical hybrid (which can be realized simply by using a conventional 3x3 optical coupler), and demonstrate its plug-and-play (i.e., phase-adjustment free and wavelength/polarization-independent) operation experimentally. We also show that the proposed phasor monitor is well suited for the use in the diagnosis of DPSK/DQPSK. The OSNR monitoring is another important function to evaluate the signal quality as well as the condition of the transmission link. We have recently proposed a new technique for monitoring the 'in-band' OSNR of DPSK/DQPSK signals. This technique estimates the OSNR by analyzing the radio frequency (RF) spectrum obtained by the self-heterodyne detection. In this paper, we briefly explain its operating principle and show the experimental results. Using this technique, we could accurately monitor the OSNR of the 10-Gb/s DPSK and 20-Gb/s DQPSK signals in a 640-km long transmission link. The results also show that the performance of the proposed technique is not sensitive to the effects of chromatic dispersion and polarization-mode dispersion.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Y. Takushima, H. Y. Choi, and Y. C. Chung "Monitoring techniques for phase and OSNR of DPSK/DQPSK signals", Proc. SPIE 7136, Optical Transmission, Switching, and Subsystems VI, 71360U (11 November 2008);

Back to Top