Before the development of optical amplifiers, optical signals had to be converted into electrical signals, then amplified, and subsequently transformed back into optical signals. This was a very complicated and expensive process. To avoid this complexity, optical amplifiers are developed, enabling the direct amplification of optical signals without the need for conversion. This streamlined approach significantly reduced costs.

Various types of optical amplifiers include:

Erbium-Doped Fiber Amplifier (EDFA) uses erbium-doped fiber as an amplification medium and are extensively deployed in Wavelength Division Multiplexing (WDM) systems. It can amplify multiple optical signals simultaneously and is commonly used in the C-band and L-band.