Lu Li

Graduation Semester and Year

2016

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Electrical Engineering

Department

Electrical Engineering

First Advisor

Michael Vasilyev

Abstract

We experimentally demonstrate, for the first time to our knowledge, a stand-alone all-optical regenerator capable of simultaneous 2R regeneration of multiple WDM channels. Recently, our group has proposed an all-optical 2R regeneration scheme for multiple WDM channels. This novel multi-channel regenerator is a modified configuration of Mamyshev 2R regenerator, in which a conventional highly-nonlinear-fiber (HNLF) is replaced by a novel group-delay-managed (GDM) nonlinear medium. The proposed multi-channel regeneration scheme uses multiple concatenated GDM unit cells, where each unit cell contains a piece of HNLF and a periodic-group-delay device (PGDD). Afterwards, the proof-of-principle experiment has also been demonstrated by using a recirculating loop to emulate of cascading multiple “fiber + PGDD” unit cells. However, the recirculating-loop-based regenerator is impractical and not useful in a real WDM systems. To make proposed regenerator practical, we build a GDM nonlinear medium with 4 or 6 “fiber + PGDD” unit cells, assisted by bi-directional Raman pumping. In this dissertation, we build a stand-alone all-optical multi-channel regenerator and present our experimental results on 3-channel all-optical 2R regeneration with 100 GHz spacing and 200 GHz spacing, as well as 100-GHz-spaced 12- and 16-channel 2R regeneration. We first investigate 2R regeneration performance for 3 channels in a GDM nonlinear medium containing four “fiber + PGDD” unit cells in 200 GHz spacing case and 100 GHz spacing case. The experimentally observed 2 dB eye-opening improvement confirms that few-channel performance is not degraded by narrower 100 GHz channel spacing. Then, the 100-GHz-spaced multi-channel regeneration experiments were performed with as many as 12 channels (12 × 10 Gb/s), and, further, 16 channels (16 × 10 Gb/s) by employing a GDM medium with 6 unit cells. All 16 channels demonstrate eye-opening improvement better than 5 dB at BER level of 10–9. In addition, we make investigations of a nonlinear-optical-loop-mirror (NOLM) based all-optical regenerator that can be used in phase-encoded systems. We experimentally demonstrate, for the first time to our knowledge, a NOLM-based phase-preserving amplitude regeneration of high-duty-cycle (50%) RZ-DPSK signals degraded by amplitude jitter and amplified spontaneous emission (ASE) noise, confirmed by a 1.5 dB eye-opening improvement. To show the path to extending the multi-channel regeneration capability to more advanced modulation formats, we propose a novel all-optical scheme of 16-QAM signal regeneration. The scheme consists of phase-sensitive amplifiers (PSAs), which are used to de-multiplex two quadratures, and new 2R regenerators, which are used for two-level amplitude signals. In the simulation, the capability of the regenerator has been demonstrated by constellation analysis. The modeling results show regenerated out signals have more than 4 dB signal-to-noise ratio (SNR) improvement on all 16 states compared to the degraded input signals.

Keywords

Nonlinear optics, All-optical regeneration, Fiber optics

Disciplines

Electrical and Computer Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

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