Enhanced Light Extraction by Photonic Quasi-Crystals in GaN Blue LEDs

Univ. of Bath, Bath, UK
IEEE Journal of Selected Topics in Quantum Electronics (Impact Factor: 4.08). 09/2009; DOI: 10.1109/JSTQE.2009.2016674
Source: IEEE Xplore

ABSTRACT The far-field profile of photonic quasi-crystal patterned and unpatterned LEDs, fabricated from commercial epitaxial substrates by electron beam lithography, has been measured prior to lapping and dicing. Emission enhancements reach a maximum of 62%, and are strongly dependent on the filling factor. Qualitative agreement is achieved between 2-D finite-difference time-domain calculations and the experimental data.

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    ABSTRACT: We design an ytterbium-doped large pitch photonic quasi-crystal fiber (PQF) for amplifying high-energy ultrashort laser pulses. The proposed fiber exhibits unique properties such as very large mode area (4660 $\mu\hbox{m}^{2}$), less attenuation (0.42 dB/km), high overlapping factor (0.55 for the fundamental mode), and low bending loss. These properties help amplify with high-average power ultrashort pulses with less distortion and high efficiency. To meet these requirements, we design a fiber with optimum gain filtering as well as loss filtering. From the numerical simulation of the analytical model, we confirm that the large pitch PQF plays an indispensable role in amplifying high-energy ultrashort pulses.
    IEEE Photonics Journal 01/2012; 4(3):943-951. · 2.36 Impact Factor
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    Recent Advances in Nanofabrication Techniques and Applications, 12/2011; , ISBN: 978-953-307-602-7

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