Field-trial of an all-optical PSK regenerator in a 40 Gbit/s, 38 channel DWDM transmission experiment

Abstract

Abstract:We report the first field-trial of a phase and amplitude regenerator highlighting the practicality of the technology. Sensitivity improvement and mitigation of transmission-induced noise with the regenerator placed in-line or at the receiver is demonstrated. IntroductionPhase and amplitude noise introduced during transmission both from optical amplifiers and the nonlinear interactions both within and between channels represents a significant limiting factor to data transmission using phase-shift keyed, PSK, modulation formats [1], [2]. Thus, the development of regeneration schemes capable of eliminating phase and amplitude noise for PSK signals is of great interest. Recently, we demonstrated a networkcompatible regenerator for simple two-level PSK encoded signals [3] and also suggested how the technology might be scaled up to allow the regeneration of more spectrally-efficient modulation formats [4]. Following our first proofof-principle demonstrations, we redesigned the two-level PSK regenerator to allow in-field tests and demonstrated its capability to operate in the presence of broadband phase noise [5] (the noise was emulated in these experiments by direct phase modulation of the signal).However, in order to truly establish the viability and capability of the technology several key further tests are required. Firstly, it is essential to establish that the regenerator can process the forms of noise generated in a real network using typical network parameters (e.g., using a DWDM network operating within the C-band subject to realistic environmental perturbations e.g. polarization drifts/acoustic perturbations) rather than noise generated by artificial means in the laboratory. Moreover, in all experiments to date, only the performance of the regenerator when placed immediately in front of the receiver was characterized -highlighting the ability to correct for particular classes of error in differentially decoded systems [5]. The natural position of such regenerators however, is along the transmission line, where they can be used to reduce the build up of non-linear noise during signal propagation. Thus, the demonstration and testing of the regenerator as an in-line device is a matter of prime importance.Here, we address both of these issues, demonstrating the key capabilities of the regenerator when operated as inline device in a real network. For the purposes of this demonstration, we used 38 DWDM 40 Gbit/s channels on a 100 GHz grid covering most of the C-band (total capacity approaching 1.5 Tbit/s) and 400 km of installed fiber.

Phase-Encoded Signal Regeneration Exploiting Phase Sensitive Amplification

“…Significant improvements in system performance in accordance with theoretical expectations were obtained in both instances and the robustness/practicality of the regenerator successfully demonstrated [8].…”

Field-Trial of an All-Optical PSK Regenerator/Multicaster in a 40 Gbit/s, 38 Channel DWDM Transmission Experiment

“…Some of the results were presented in less detail in [13]. Specifically, (i) how the regenerator works as an in-line device, (ii) how it works in an installed transmission line subject to real world noise, (iii) its multicasting and wavelength conversion capabilities, and finally, (iv) its tolerance to residual (uncompensated) link dispersion.…”

Phase sensitive parametric mixers for coherent all-optical signal processing

“…Depending on the relative phase between the interacting waves, the signal experiences either gain or de-amplification, allowing independent control of the I and Q phase quadratures [1]. This process has been used for the regeneration of binary phase encoded (BPSK) signals [1,2], and recently a field trial of a black-box BPSK regenerator highlighted the practicality of such schemes [3]. The functionality of the PS mixer has been radically enhanced by a novel general technique that allows the multi-level all-optical quantization of phase encoded optical signals in a simple, compact and reconfigurable system employing a single nonlinear optical element [4].…”