Resonant-cavity LED transceiver arrays for optical wireless communication

155Mb/s operation of an optical wireless link is achieved by using the spectral characteristics and angular emission spectra of a 7-element tracking array of 980nm RC-LEDs. Preliminary results show extension to 200 Mb/s/channel. © 2006 Optical Society of America.

Refractive index evaluation of multi-walled carbon nanotube arrays

Transmission terahertz time-domain spectroscopy (THz-TDS) measurements of carbon nanotube arrays are presented. A relatively thin film with vertically aligned multi-walled carbon nanotubes has been prepared and measured using THz-TDS. Experimental results were obtained from 80GHz to 2.5THz, and the sample has been characterized by extracting the relative permittivity of the carbon nanotubes. A combination of the Maxwell-Garnett and Drude models within the frequency range provide a good fit to the measured permittivity.

Enhanced reflection from arrays of silicon based inverted nanocones

We report enhanced reflection displayed by arrays of silicon based inverted nanocones. Theoretical studies suggest that such arrays display enhanced reflection and photonic band gaps within the optical and near infrared regions. Measured results show three to four fold enhancement in reflection and agree well with calculations. Such arrays can be used to enhance infrared reflection in photovoltaic devices which mostly contribute towards heating. © 2011 American Institute of Physics.

1-3 Piezocomposite design optimised for high frequency kerfless transducer arrays

Piezocomposites that can operate at frequencies above 30 MHz without spurious modes are required in order to develop sufficiently sensitive high frequency arrays for high resolution imaging. However, scaling down of conventional piezocomposite fabrication techniques becomes increasingly difficult as dimensions decrease with increasing frequency. The approach presented here is to use micro-moulded 1-3 piezocomposites and a distribution of piezoelectric segment size and separation. Innovative approaches to composite pattern design, based on a randomized spatial distribution, are presented. Micro-moulding techniques are shown to be suitable for fabricating composites with dimensions required for high frequency composites. Randomized piezocomposite patterns are modeled and are shown to suppress spurious modes.

High efficiency liquid crystal lasers giving "white light" emission from arrays and flexible substrates

The self-organization of the helical structure of chiral nematic liquid crystals combined with their sensitivity to electric fields makes them particularly interesting for low-threshold, wavelength tunable laser devices. We have studied these organic lasers in detail, ranging from the influence specific macroscopic properties, such as birefringence and order parameter, have on the output characteristics, to practical systems in the form of two-dimensional arrays, double-pass geometries and paintable lasers. Furthermore, even though chiral nematics are responsive to electric fields there is no facile means by which the helix periodicity can be adjusted, thereby allowing laser wavelength tuning, without adversely affecting the optical quality of the resonator. Therefore, in addition to studying the liquid crystal lasers, we have focused on finding a novel method with which to alter the periodicity of a chiral nematic using electric fields without inducing defects and degrading the optical quality factor of the resonator. This paper presents an overview of our research, describing (i) the correlation between laser output and material properties,(ii) the importance of the gain medium,(iii) multicolor laser arrays, and (iv) high slope efficiency (>60%) silicon back-plane devices. Overall we conclude that these materials have great potential for use in versatile organic laser systems.