| Summary: | <p>Visible Light Communication (VLC) has gained significant attention in the last few years. In VLC,
light from existing solid-state light sources is used as a data carrier. The maximum capacity of a VLC
channel, like other communications systems, is dependent upon two key factors i.e. the signal-to-noise ratio (SNR) at the receiver and channel bandwidth. VLC systems rely upon light-emitting diode
(LED) and lasers as the light sources. Unfortunately, due to the limited bandwidths of most
commercial LEDs, a higher data rate can only be achieved by increasing the SNR at the receiver. One
simple way to increase SNR is to use a large detector, however, this results in larger capacitance
which consequently reduces the bandwidth of the detector. Previously, optical concentrators such as
parabolic and compound parabolic concentrators have been coupled to the detectors to concentrate
light onto the detector, however, these concentrators are limited by the conservation of etendue.
Alternatively, a relatively new approach is to use fluorescent concentrators (FC) which do not
conserve etendue and can provide much higher optical gains.</p>
<p>In this thesis, the performance of several types of FC is characterised for use in VLC links which
includes gain, bandwidth, absorption-emission spectra, FOV and maximum achievable data rates.
The selective absorption of different wavelengths by the FC means that they act as natural filters,
therefore, the performance of a blue filter was compared to an FC. Experimental results are presented
which show that the FC not only increased the FOV but also increased the maximum achievable data
rate. In addition, the feasibility of enabling a wavelength division multiplexing (WDM) system with
FCs is discussed. More importantly, a wide FOV receiver for a smartphone that was designed by
coupling a commercially available fluorescent fibre to an APD is presented. This receiver provides a
wide FOV of ±120°, for a smartphone application. Finally, a method to predict the OOK data rate is
described with the experimental results.</p>
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