All-optical multilevel amplitude regeneration in a single nonlinear optical loop mirror

We experimentally demonstrate all-optical amplitude regeneration of 4-level pulse amplitude modulated signals (PAM4) based on a single nonlinear optical loop mirror (NOLM). Four power-plateau regions are achieved using return-to-zero (RZ) pulses of narrow pulse-width, enabling large nonlinear phase shifts within the highly nonlinear fiber (HNLF). We quantify noise suppression characteristics at each amplitude level and obtain an overall EVM improvement of 0.92dB by optimizing input power and distortion strength. A theoretical analysis has been also carried out matching the experimental results and revealing the design characteristics of the regenerator’s nonlinear transfer function

Nonlinear loop mirror-based all-optical signal processing in fiber-optic communications

All-optical data processing is expected to play a major role in future optical communications. The fiber nonlinear optical loop mirror (NOLM) is a valuable tool in optical signal processing applications. This paper presents an overview of our recent advances in developing NOLM-based all-optical processing techniques for application in fiber-optic communications. The use of in-line NOLMs as a general technique for all-optical passive 2R (reamplification, reshaping) regeneration of return-to-zero (RZ) on-off keyed signals in both high-speed, ultralong-distance transmission systems and terrestrial photonic networks is reviewed. In this context, a theoretical model enabling the description of the stable propagation of carrier pulses with periodic all-optical self-regeneration in fiber systems with in-line deployment of nonlinear optical devices is presented. A novel, simple pulse processing scheme using nonlinear broadening in normal dispersion fiber and loop mirror intensity filtering is described, and its employment is demonstrated as an optical decision element at a RZ receiver as well as an in-line device to realize a transmission technique of periodic all-optical RZ-nonreturn-to-zero-like format conversion. The important issue of phase-preserving regeneration of phase-encoded signals is also addressed by presenting a new design of NOLM based on distributed Raman amplification in the loop fiber. © 2008 Elsevier Inc. All rights reserved

Study On All-Optical Signal Processing by Semiconductor Optical Amplifiers for Ultra-High-Speed Optical Fiber Communications

制度:新 ; 報告番号:乙2307号 ; 学位の種類:博士(工学) ; 授与年月日:2011/2/25 ; 早大学位記番号:新564

All Optical Regeneration

All optical regeneration methods and systems can be realized through an exponential amplifier and a limiting amplifier, which could be two independent devices (one piece of fiber with parametric amplification and a semiconductor optical amplifier operating at saturation state) or one single device (one piece of fiber). The signal quality and the extinction ratio after regeneration are significantly improved compared with the degraded incoming data using a parametric amplifier with the data signal to be regenerated as the pump. The regenerated data has an extinction ratio as high as 14 dB, an extinction ratio enhancement of approximately 5 dB and an approximately 5 dB negative power penalty. This regeneration schemes are format transparent (RZ and NRZ), and provide noise reduction both for bit 1s and bit 0s of the data sequence. The regeneration method and apparatus that just utilizes fibers has the additional capability of ultrafast response speed (several femtoseconds due to the Ker