Single mode fiber uses laser light sources, with commonly used wavelengths of 1310nm and 1550nm, which perform well in terms of transmission loss and bandwidth. A broadband light source (BLS), as opposed to the monochromatic light source, generates light throughout a wide range of wavelengths. The narrow emission. Currently, commercially available fiber optic technologies may utilize one of three types of light source- laser, LED, or VCSEL. The light from the end of the fiber is coupled to a receiver where a detector converts the light into an electrical signal which is then conditioned properly for use by. Many fiber systems use light sources of gallium arsenide (GaAs) and gallium aluminium arsenide (GaAIAs) emitting at 750-900 nm. The performance is characterized by channel insertion loss (cabling attenuation), and modal bandwidth (for multimode fiber). The use of mode-conditioning patch cords if required.