EDFA effect

Hi Mohammad,

In a general sense, when the amplifier is used before the receiver (after the fiber line), it is called “preamplifier” and is used to amplify the signal so as to overcome the receiver noise. When it’s used after the transmitter (before the fiber), it is called “power booster” and is used to amplify the power which is not yet mixed with any noise from fiber (source: Mr Keiser’s book on optical communications). It can be used for RoF systems in the same sense.

Connecting an optical amplifier at the output of the fiber will help to overcome the fiber attenuation loss. Hence the signal will get boosted before being photo detected.

Agree with Alisthu and Dhanajay.For just to explain this more i write this

A booster amplifier operates at the transmission side of the link. It features high input power, high output power, and medium
optical gain. Boosters are designed to amplify aggregated optical input power for reach extension.

An in-line amplifier operates in the middle of an optical link. It features medium to low input power, high output power,
high optical gain, and a low noise figure. In-line amplifiers are designed for optical amplification between two network nodes on the main optical link.

A pre-amplifier operates at the receiving end of an optical link. It features medium to low input power, medium output power, and medium gain. Pre-amplifiers are designed for optical amplification to compensate for losses in a demultiplexer located
near the optical receiver

agree with above;

1.for post amplifiers (used after transmitter)you have to keep NON-linear effects (NLE) in mind. NLE is hiher at higher power levels.

2.pre-amplifers are required to compensate losses in optical line.THere is also dipersion,NLE in optical fiber ,which contribute to noise at RECEIVER END(RX).this amplifiers also amplifies noise at same time .there choice of gain of this amplifier depend on threshold level and type of RX