Fiber Optic Light Source for Optical Communication Systems

Requirement light source in a fiber optic communication

Light source plays an important role in a system of optical fiber communication. The optical fiber core system consists of a transmitter, an optical fiber, and a receiver. The transmitter has a light source that is modulated by a suitable drive circuit according to the signal to be transmitted.

The choice of an optical source is determined by the particular application. For high speed systems of optical fiber communication, which operate at speed greater than 1 Gbit / s, the light source selection is even more critical. The source must meet several basic requirements.

The first requirement is that it must emit a wavelength that corresponds to the low-loss window of fused silica fiber material more common, namely 1.5um and 1.3um windows. This is very important because the fiber links often operate at several tens of kilometers span without repeater. For a given optical power at the wavelength, the less fiber loss would result in larger repeater spacings.

The second requirement is high speed digital modulation. Current generation of optical fiber systems of communication have reached the speed of 40 Gb / s and 100 Gb / s. This requires that the source of light to be modulated at speeds over 2.5 Gb / s. To fulfill this requirement, two kinds of modulation methods have been developed. The first type is to modulate the light source directly to the desired speed. The second type of modulation is the use of an external LiNbO3 modulator. For the second type, the light source is needed to give constant power. Read More