Enhanced range for OTDR-like dispersion map measurements

Abstract

We report on enhancement of the range, reliability, and accuracy of optical-time-domain-reflection- (OTDR-) like measurement of an optical fiber's dispersion map, D(z), through the combined use of Raman gain, an appropriate seed at the four-wave mixing frequency, and a greatly improved algorithm for reduction of the data. In particular, in measurements made from only one end of the fiber, we have demonstrated a range of 75 km in dispersion-shifted fiber and of 22.5 km in high-loss dispersion-compensating fiber.

Sensitive and Accurate Dispersion Map Extraction of HNLFs by Frequency Tuning of a Degenerate FWM

“…The efficiency of the nonlinear interaction is implicitly measured at either ends of the fiber, and the sought-after dispersion map is extracted by sweeping the nonlinear interaction spot along the fiber. The localized nonlinear interaction can be initiated by either two co-directional waves with different velocities [19], or two contra-directional waves colliding each other [6], [20]- [22]. The latter strategy is adopted here since it can reach the meter-scale resolution [6], [20] while the resolution of the earlier strategy is limited to the kilometer scales [19].…”

“…The localized nonlinear interaction can be initiated by either two co-directional waves with different velocities [19], or two contra-directional waves colliding each other [6], [20]- [22]. The latter strategy is adopted here since it can reach the meter-scale resolution [6], [20] while the resolution of the earlier strategy is limited to the kilometer scales [19]. There are number of elegant works [20]- [22] which have used nonlinear localized interaction between contra-directional waves, and successfully extracted the dispersion map of SMFs or DSFs.…”

“…The latter strategy is adopted here since it can reach the meter-scale resolution [6], [20] while the resolution of the earlier strategy is limited to the kilometer scales [19]. There are number of elegant works [20]- [22] which have used nonlinear localized interaction between contra-directional waves, and successfully extracted the dispersion map of SMFs or DSFs. However, these methods are not useful for nearly dispersion-less HNLFs since localized nonlinear interaction in such fibers is not sensitive enough to dispersion characteristics [6].…”

Nonlinear Effects in Optical Fibers

“…From here arise the necessity to have a technique that can allow to map the longitudinal distribution of chromatic dispersion along a fiber. The method proposed by Mollenauer et al [29,30] and based on four wave mixing, is a convenient approach for the measurement of chromatic dispersion maps in DSF fibers. In this chapter we show that when the coupling length h is relatively large (as is typically the case for most older installed DSF cables) the method presents severe limits.…”

“…C'est pourquoi il est nécessaire d'avoir une technique qui permet d'obtenir la distribution longitudinale de la dispersion chromatique le long de la fibre. La méthode proposée par Mollenauer et al [29,30] et basée sur le mélangeà quatre ondes est une bonne approche pour la mesure distribuée de la dispersion chromatique dans les fibresà dispersion décalée. Dans ce chapitre, on montre que lorsque la longueur de couplage h est relativement grande (comme c'est généralement le cas pour la plupart des vieux câbles DSF installés) la méthode présente de sévères limites.…”