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