Professor Robert Taylor

Abstract:

There is a great potential in the development of versatile singlephoton devices based on nitride-based single quantum dots due to their unique properties. Their emission can be engineered to span a wide spectral range from the ultraviolet to the blue and green regions of the spectrum which may prove important for several applications such as free-space quantum cryptography and low-noise absorption measurements. It is also possible to dynamically tune the wavelength of the emitted single photons over a wide range by controlling the internal piezoelectric field using externally applied electric fields. The nitrides also have the potential of providing devices which operate at relatively high temperatures. In this contribution, we review the progress made so far towards the development of optically excited and electrically driven single photon sources based on these structures. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Abstract:

The exact mechanism for non-linear sub-bandgap excitation of single InGaN quantum dots (QDs) has been investigated using interferometric autocorrelation techniques based around a near-infrared (NIR) excitation laser. We identify unambiguously the heavily favoured two-photon absorption (TPA) as being crucial in the observed background reduction for such Nitride structures and compare systematically the relative merits of both the linear (blue) and non-linear (NIR) excitation regimes on several apertures of a masked sample. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Abstract:

We develop an effective way to engineer a two-dimensional GaAs photonic crystal slab with its leaky eigenmodes at desired wavelengths by investigating its spectral dispersion, particularly in terms of transmission efficiency spectra at different launch angles of the light beam. Structural parameters for the photonic crystal slab with leaky eigenmode wavelengths at both 1492 nm and 1519 nm are obtained. This may lead to the enhanced luminescence from erbium-doped trinitride-template fullerenes (Er3N@C80) on the surface of the photonic crystal slabs. © 2009 Elsevier B.V.

Abstract:

Photoluminescence spectroscopic measurements have allowed the acquisition of high resolution spectra at low temperature for the endohedral metallofullerenes, Er2 @ C82 (isomer I) and Er2 C2 @ C82 (isomer I). The characteristic emission in the 1.5-1.6 μm region corresponds to the 4 I13 / 2 (m) → 4 I15 / 2 (n) transitions of the Er3 + ion for both molecules. The emission arising from Er2 C2 @ C82 (I) appears acuminated (narrow lines that taper to a point) when compared with that of Er2 @ C82 (I). The Er2 C2 @ C82 (I) emission linewidths are comparable to those found in crystals, making this molecule of interest for applications where accessible, well-defined quantum states are required. © 2009 Elsevier B.V. All rights reserved.