Format transparent, wide range and independent dispersion monitoring method based on four-wave mixing

Simultaneous chromatic dispersion monitoring and optical modulation format identification utilizing four wave mixing

“…2 and 3. Ten modulation formats are considered and the device parameters used are the same as that reported previously [10]. The FWM based nonlinear PTF has an order of about 5.5.…”

“…The output curve of the CD monitor is symmetric about the zero-dispersion point, as CD induced optical pulse distortions are the same for CDs with the same magnitude but opposite sign. Thus using a simple symmetric center search algorithm in combination with a TDC, the zero CD point and the residual CD can be easily identified [10]. The position of the symmetric center is only determined by CD and is insensitive to PMD and OSNR, thus CD can be monitored independently.…”

“…The x-axis denotes the CD applied onto the signal by the TDC. In the second step the symmetric center is found by simple search algorithm [10] and the CD is equal to the opposite signed TDC dispersion at that symmetric center. We note that the monitoring range is not limited by the Talbot effect, but by the tuning range of the TDC.…”

“…In previous works, we proposed a highly sensitive all optical CD monitor based on exponential power transfer function (PTF) provided by FWM in highly nonlinear fibers (HNLFs) [9]. This method is then improved to expand the CD monitoring range, be robust to PMD and OSNR influence, and accommodate on-off keying (OOK) and advanced modulation formats [10]. In this paper it is demonstrated that the highly sensitive all-optical CD monitor can also be used to realize MFI function.…”