The source used for a fiber optic transmitter needs to meet several criteria: it has to be at the correct wavelength, be able to be modulated fast enough to transmit data and be efficiently coupled into fiber. The transmitter takes an electrical input and converts it to an optical output from a laser diode or LED. The light from the end of the fiber is coupled to a receiver. Fiber-optic communication systems require a light source to generate the signal that the fiber transmits. Some inexpensive short-distance systems use LEDs that emit visible light, but most systems carry. ials needed to obtain efficient lasing at room temperature. Whether you are installing a new fiber network, troubleshooting signal loss, or performing.