01-06-2012, 03:16 PM
The Evolution of Optical Fibre Communication Systems
[attachment=23881]
Introduction
The demand for high-capacity long-haul telecommunication systems is increasing
at a steady rate, and is expected to accelerate in the next decade
[1]. At the same time, communication networks which cover long distances
and serve large areas with a large information capacity are also in increasing
demand [2]. To satisfy the requirements on long distances, the communication
channel must have a very low loss. On the other hand, a large
information capacity can only be achieved with a wide system bandwidth
which can support a high data bit rate (> Gbit/s) [3]. Reducing the loss
whilst increasing the bandwidth of the communication channels is therefore
essential for future telecommunications systems.
Of the many different types of communication channels available, optical
fibres have proved to be the most promising [4, 5]. The first advantage of an
optical fibre is its low attenuation. Typical values of attenuation factor in
Modified Chemical Vapour Deposition (MCVD) optical fibres are plotted
against wavelength of the electromagnetic carrier in Fig. 1.1 [6]. At present,
optical fibres with loss coefficients of less than 0.25 dB/km around emission
wavelengths of 1.55 μm are available [7]. This remarkable progress in
fibre manufacturing technology has led to wide applications of long distance
optical fibre communications in recent years. Furthermore, optical fibres
can also transmit signals over a wide bandwidth because the electromagnetic
carrier in optical fibres has a frequency in the optical frequency region
(≈ 1014 Hz).
[attachment=23881]
Introduction
The demand for high-capacity long-haul telecommunication systems is increasing
at a steady rate, and is expected to accelerate in the next decade
[1]. At the same time, communication networks which cover long distances
and serve large areas with a large information capacity are also in increasing
demand [2]. To satisfy the requirements on long distances, the communication
channel must have a very low loss. On the other hand, a large
information capacity can only be achieved with a wide system bandwidth
which can support a high data bit rate (> Gbit/s) [3]. Reducing the loss
whilst increasing the bandwidth of the communication channels is therefore
essential for future telecommunications systems.
Of the many different types of communication channels available, optical
fibres have proved to be the most promising [4, 5]. The first advantage of an
optical fibre is its low attenuation. Typical values of attenuation factor in
Modified Chemical Vapour Deposition (MCVD) optical fibres are plotted
against wavelength of the electromagnetic carrier in Fig. 1.1 [6]. At present,
optical fibres with loss coefficients of less than 0.25 dB/km around emission
wavelengths of 1.55 μm are available [7]. This remarkable progress in
fibre manufacturing technology has led to wide applications of long distance
optical fibre communications in recent years. Furthermore, optical fibres
can also transmit signals over a wide bandwidth because the electromagnetic
carrier in optical fibres has a frequency in the optical frequency region
(≈ 1014 Hz).