Monitoring Techniques for Phase and OSNR of DPSK/DQPSK Signals
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.
Fiber optic communications phase modulation optical performance monitoring differential phase-shift-keying optical phasor optical signal-to-noise ratio
Y.Takushima H.Y.Choi Y.C.Chung
Department of Electrical Engineering,Korea Advanced Institute of Science and Technology373-1 Guseong Department of Electrical Engineering,Korea Advanced Institute of Science and Technology 373-1 Guseon
国际会议
2008亚太光通信会议(Asia-Pacific Optical Communications 2008)
杭州
英文
2008-10-26（万方平台首次上网日期，不代表论文的发表时间）