Fatima C. Garcia Gunning

Spectral density enhancement using coherent WDM

It is shown by numerical simulations that a significant increase in the spectral density of a 40-Gb/s wavelength-division-multiplexing (WDM) system can be obtained by controlling the phase of adjacent WDM channels. These simulations are confirmed experimentally at 40 Gb/s using a coherent comb source. This technique allows the spectral density of a nonreturn-to-zero WDM system to be increased from 0.4 to 1 b/s/Hz in a single polarization. Optical filter optimization is required to minimize power crosstalk, and appropriate strategies are discussed in this letter.

Multi-wavelength source using low drive-voltage amplitude modulators for optical communications

A simple and cost-effective technique for generating a flat, square-shaped multi-wavelength optical comb with 42.6 GHz line spacing and over 0.5 THz of total bandwidth is presented. A detailed theoretical analysis is presented, showing that using two concatenated modulators driven with voltages of 3.5 V(pi) are necessary to generate 11 comb lines with a flatness below 2dB. This performance is experimentally demonstrated using two cascaded Versawave 40 Gbit/s low drive voltage electro-optic polarisation modulators, where an 11 channel optical comb with a flatness of 1.9 dB and a side-mode-suppression ratio (SMSR) of 12.6 dB was obtained.

DPSK Signal Regeneration With a Dual-Pump Nondegenerate Phase-Sensitive Amplifier

We demonstrate, for the first time to our knowledge, regeneration of a 42.66-Gb/s differential phase-shift keyed signal using a dual-pump nondegenerate four-wave-mixing-based fiber-optic parametric amplifier. The regenerative performance of the subsystem is characterized in terms of bit-error rate against narrowband and wideband introduced noise. While a strong receiver sensitivity improvement, up to 20 dB, is noticed against narrowband noise, against quasi-random (wideband) noise we observe a regeneration of 2.7 dB.

Dispersion tolerance of coherent WDM

We present the transmission of a 298.2-Gb/s copolarized coherent wavelength-division-multiplexing system over 80 km of standard single-mode fiber, achieving an information spectral density of 1 b/s/Hz with no prefilters at the transmitter. Odd and even tributary channels were encoded with data and delayed-data-bar pseudorandom binary sequence 27-1 patterns. The dispersion tolerance is investigated, and the dispersion penalty of this system is improved through adjustment of the relative phase of adjacent channels. Under optimum conditions, the dispersion penalty could be reduced from over 3 dB to less than 1 dB

Unrepeatered field transmission of 2 Tbit/s multi-banded coherent WDM over 124 km of installed SMF

In this paper we report field transmission of a 2 Tbit/s multi-banded Coherent WDM signal over BT Irelands installed SMF, using EDFA amplification only, with mixed Ethernet (with FEC) and PRBS payloads. To the best of our knowledge, the results obtained represent the highest total capacity transmitted over installed SMF with orthogonal subcarriers. BERs below 10(-5) and no frame-loss were recorded for all 49 subcarriers. Extended BER measurements over several hours showed fluctuations that can be attributed to PMD and to dynamic effects associated with clock instabilities.

Towards 1TbE using Coherent WDM

In this paper we report the transmission properties of a 0.3 Tbit/s coherent WDM signal and confirm the scalability of this signal to 0.6 Tbit/s using polarisation division multiplexing.

Coherent WDM: the achievement of high information spectral density through phase control within the transmitter

We review a new transmission technique, coherent WDM, which allows high information spectral density to be achieved in a simple and low-cost configuration using phase control at the transmitter.

Phase locking and carrier extraction schemes for phase sensitive amplification

We demonstrate two schemes which enable simultaneous phase locking, carrier extraction and frequency shifting for use in stand-alone phase sensitive amplifiers. The schemes provide phase locked pumps at appropriate frequency spacing for a number of non-degenerate PSA configurations.

0.6Tbit/s Capacity and 2bit/s/Hz Spectral Efficiency at 42.6Gsymbol/s Using a Single DFB Laser with NRZ Coherent WDM and Polarisation Multiplexing

The capacity of a single-source coherent WDM (CoWDM) system is doubled from 298.2 Gbit/s to 596.5 Gbit/s by introducing polarisation multiplexing (PolMUX). This is achieved by generating a band of seven non-return-to-zero (NRZ) encoded channels at 42.6 Gsymbol/s. BER characterisations for single channel, 1 bit/s/Hz CoWDM channels and 2 bit/s/Hz CoWDM+PolMUX are performed. This work obtained high information spectral density of 2 b/s/Hz, allowing ISDs in excess of 1.8 b/s/Hz in a banded multi-Terabit/s system.

Integration of a 3D hydrogel matrix within a hollow core photonic crystal fibre for DNA probe immobilization

In this paper, we demonstrate the integration of a 3D hydrogel matrix within a hollow core photonic crystal fibre (HC-PCF). In addition, we also show the fluorescence of Cy5-labelled DNA molecules immobilized within the hydrogel formed in two different types of HC-PCF. The 3D hydrogel matrix is designed to bind with the amino groups of biomolecules using an appropriate cross-linker, providing higher sensitivity and selectivity than the standard 2D coverage, enabling a greater number of probe molecules to be available per unit area. The HC-PCFs, on the other hand, can be designed to maximize the capture of fluorescence to improve sensitivity and provide longer interaction lengths. This could enable the development of fibre-based point-of-care and remote systems, where the enhanced sensitivity would relax the constraints placed on sources and detectors. In this paper, we will discuss the formation of such polyethylene glycol diacrylate (PEGDA) hydrogels within a HC-PCF, including their optical properties such as light propagation and auto-fluorescence.