DocumentCode :
818146
Title :
A Review of the Polarization-Nulling Technique for Monitoring Optical-Signal-to-Noise Ratio in Dynamic WDM Networks
Author :
Lee, J.H. ; Choi, H.Y. ; Shin, S.K. ; Chung, Y.C.
Author_Institution :
Dept. of Electr. Eng., Korea Adv. Inst. of Sci. & Technol., Daejeon
Volume :
24
Issue :
11
fYear :
2006
Firstpage :
4162
Lastpage :
4171
Abstract :
The polarization-nulling technique utilizes the different properties of optical signal and amplified spontaneous emission (ASE) noise for accurate monitoring of the optical-signal-to-noise ratio (OSNR) in dynamic optical networks. However, the performance of this technique is bound to be deteriorated if the signal is depolarized by polarization-mode dispersion and/or nonlinear birefringence or the ASE noise is partially polarized due to polarization-dependent loss (PDL) in the transmission link. The authors analyze these effects on the performance of the polarization-nulling technique and introduce several techniques to overcome these problems. These improved versions of the polarization-nulling techniques could monitor the OSNR with accuracy of better than plusmn1 dB, even when the differential group delay is as large as 60 ps. These techniques could also negate the effect of the signal depolarization caused by nonlinear birefringence in a highly nonlinear transmission link. The effect of the partially polarized ASE noise due to PDL is found to be not severe in most cases, as long as the PDL/span is smaller than 0.2 dB. To verify the possibility of using the polarization-nulling technique in real systems, the OSNR of the wavelength-division-multiplexed (WDM) signals transmitted through a 120-km-long aerial fiber link is measured for one week. No significant degradation in the monitoring accuracy is observed during this long-term measurement. In addition, the performance of the polarization-nulling technique in an ultralong-haul transmission link is evaluated by using a 640-km-long recirculating loop. The results show that this technique could accurately measure the OSNR in the transmission link longer than 3200 km. From these results, the authors conclude that the polarization-nulling technique is well suited for monitoring the OSNR in dynamic WDM networks
Keywords :
birefringence; monitoring; optical fibre dispersion; optical fibre losses; optical fibre networks; optical fibre polarisation; optical noise; superradiance; wavelength division multiplexing; 120 km; 640 km; ASE noise; OSNR; WDM networks; amplified spontaneous emission; differential group delay; nonlinear birefringence; optical-signal-to-noise ratio; polarization nulling; polarization-dependent loss; polarization-mode dispersion; recirculating loop; signal depolarization; wavelength division multiplexing; Fiber nonlinear optics; Monitoring; Nonlinear optics; Optical fiber networks; Optical noise; Optical polarization; Page description languages; Signal to noise ratio; Stimulated emission; WDM networks; Dynamic optical network; nonlinear birefringence; optical performance monitoring (OPM); optical-signal-to-noise ratio (OSNR); polarization fluctuation; polarization-dependent loss (PDL); polarization-mode dispersion (PMD); polarization-nulling technique;
fLanguage :
English
Journal_Title :
Lightwave Technology, Journal of
Publisher :
ieee
ISSN :
0733-8724
Type :
jour
DOI :
10.1109/JLT.2006.883120
Filename :
4012203
Link To Document :
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