Inclusion of research labs in Engineering as learning playgrounds

Traditional teaching practices in Ireland for “hard”-science subjects, such as Physics or Engineering, are still prevalently based on whiteboard content delivery, PowerPoint-based methods, and sometimes, within under-funded purposed-built teaching labs, leaving very little manoeuvre or willingness to incorporate student interaction, in addition to a strong focus on end of semester exam based assessment of learning. Very often any deviation from traditional methods of teaching and assessment are perceived as “dumbing down” the course. The proposal of this Lightning Talk is to show how enabling flexibility in the teaching environment, by incorporating either topical research discussions or bringing a high-tech research lab to a teaching module, can stimulate student engagement, curiosity, discovery and learning. Moreover, the talk will also contain a discussion on using different assessment techniques, such as consultation surveys and reports, where a richer picture of true understanding can be drafted, and compare outcomes between report-based and exam-based types of assessment, showing no signs of “dumbing down”

Hollow core photonic crystal fiber based viscometer with Raman spectroscopy

The velocity of a liquid flowing through the core of a hollow core photonic crystal fiber (driven by capillary forces) is used for the determination of a liquid's viscosity, using volumes of less than 10 nl. The simple optical technique used is based on the change in propagation characteristics of the fiber as it fills with the liquid of interest via capillary action, monitored by a laser source. Furthermore, the liquid filled hollow core photonic crystal fiber is then used as a vessel to collect Raman scattering from the sample to determine the molecular fingerprint of the liquid under study. This approach has a wide variety of indicative uses in cases where nano-liter samples are necessary. We use 10–12 cm lengths of hollow core photonic crystal fibers to determine the viscosity and Raman spectra of small volumes of two types of monosaccharides diluted in a phosphate buffer solution to demonstrate the principle. The observed Raman signal is strongest when only the core of the hollow core photonic crystal fiber is filled, and gradually decays as the rest of the fiber fills with the sample

Multi-wavelength regeneration of phase encoded signals based on phase sensitive amplifiers

Future high capacity optical links will have to make use of frequent signal regeneration to enable long distance transmission. In this respect, the role of all-optical signal processing becomes increasingly important because of its potential to mitigate signal impairments at low cost and power consumption. More substantial benefits are expected if regeneration is achieved simultaneously on a multiple signal band. Until recently, this had been achieved only for on-off keying modulation formats. However, as in future transmission links the information will be encoded also in the phase for enhancing the spectral efficiency, novel subsystem concepts will be needed for multichannel processing of such advanced signal formats. In this paper we show that phase sensitive amplifiers can be an ideal technology platform for developing such regenerators and we discuss our recent demonstration of the first multi-channel regenerator for phase encoded signals

DNA probe detection within 3D hydrogel matrix in a hollow core photonic crystal fibre

In this paper, we report for the first time the detection of a Cy5-labelled DNA probe immobilised within a 3D hydrogel matrix formed, inside a hollow core Photonic Crystal Fibre (HC-PCF). We show both the sensitivity of fluorescence detection inside the HC-PCF using a supercontinuum light source and of the variation of the luminescence intensity with the concentration DNA probe within the hydrogel. The 3D hydrogel matrix is a network of polymer chains, which is expected to provide highly sensitive detection and selection of bio-molecules, in comparison with 2D coverage. The biocompatibility of hydrogel in the HC-PCF suggests numerous applications associated with immobilised DNA probe detection for point-of-care or remote systems

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 Vp 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

Demonstration of CoWDM using DPSK modulator array with injection-locked lasers

A practical implementation of coherent wavelength division multiplexing (CoWDM) is demonstrated for the first time using injection-locked lasers and a DPSK modulator array. For a 31.99 Gbit/s system (three subcarriers at 10.664 Gbit/s) the null-to-null spectral bandwidth was only 42.656 GHz and the average receiver sensitivity measured was -33.5 dBm when all subcarrier phases were optimised

PMD tolerance of 288 Gbit/s Coherent WDM and transmission over unrepeatered 124 km of field-installed single mode optical fiber

Low-cost, high-capacity optical transmission systems are required for metropolitan area networks. Direct-detected multi-carrier systems are attractive candidates, but polarization mode dispersion (PMD) is one of the major impairments that limits their performance. In this paper, we report the first experimental analysis of the PMD tolerance of a 288Gbit/s NRZ-OOK Coherent Wavelength Division Multiplexing system. The results show that this impairment is determined primarily by the subcarrier baud rate. We confirm the robustness of the system to PMD by demonstrating error-free performance over an unrepeatered 124km field-installed single-mode fiber with a negligible penalty of 0.3dB compared to the back-to-back measurements. (C) 2010 Optical Society of Americ

Impact of Raman amplification on a 2 Tb/s coherent WDM system

The impact of hybrid erbium-doped fiber amplifier (EDFA)/Raman amplification on a spectrally efficient coherent-wavelength-division-multiplexed (CoWDM) optical communication system is experimentally studied and modeled. Simulations suggested that 23-dB Raman gain over an unrepeatered span of 124 km single-mode fiber would allow a decrease of the mean input power of ~6 dB for a fixed bit-error rate (BER). Experimentally we demonstrated 1.2-dB Q-factor improvement for a 2-Tb/s seven-band CoWDM with backward Raman amplification. The system delivered an optical signal-to-noise ratio of 35 dB at the output of the receiver preamplifier providing a worst-case BER of 2 × 10 -6 over 49 subcarriers at 42.8 Gbaud, leaving a system margin (in terms of Q -factor) of ~4 dB from the forward-error correction threshold

Key enabling technologies for optical communications at 2000 nm

This paper discusses the potential for opening a new wavelength window at the 2 μm waveband for optical communications, showing current limitations of the system’s performance. It focuses on novel results for key enabling technologies, including the analysis of laser injection locking at this waveband, an improved responsivity for bulk and strained InGaAs edge-couple detectors, and also an increased gain profile for thulium-doped fiber amplifiers

Development of thulium-doped fibre amplifiers for the 2μm waveband

In this paper we show the analysis of Thulium Doped Fibre Amplifier(TDFA) gain dependence on pump laser wavelength and thulium doped fibre length. Thulium doped fibres of lengths varying from 0.5m to 3m are pumped with 785nm and 1550nm lasers in single and dual pumping schemes. Small signal gain up to 16dB was achieved at 2μm for a low pump power of 150mW. A potential wide amplifications bandwidth ranging from 1680nm to 2025nm is observed in the Amplified Spontaneous Emission(ASE) spectrum