Jun 20 2014
Bandwidth is the width of a wavelength range with regard to a specific part of the spectrum which transmits incident energy via a filter. It is also referred to as full width at half maximum (FWHM), which may be used to determine the resolution of spectrometers, spectral width of optical communication sources and duration of pulse waveforms. In optical-fiber communication systems, bandwidth is used for determining the data rate.
The values of optical bandwidth can be specified in terms of wavelength or frequency. The conversion factor between nanometers and gigahertz is based on the frequency or center wavelength due to the inverse relationship of wavelength and frequency. The optical bandwidth of a light source is related to temporal coherence, which is characterized with the coherence time. Q-factor, for both passive oscillators and output of oscillators, is defined as the ratio of oscillation frequency to bandwidth.
Bandwidth-distance product is commonly used in optical fiber communication. It is usually a product of the maximum optical bandwidth and length of a fiber optic link. Maximum bandwidth is often related to the data rate with a conversion factor in the used modulation format. This concept is useful for determining the performance of various types of fiber-optic links. One of the major limitations of bandwidth–distance product is that the bit error rate increases for very high data rates.
Sources and Further Reading