What are the functions of repeater in optical fiber communication? describe in details.?

The idea of repeaters in optical fiber communication is exactly the same idea as in copper cable communication and then again in radio communication. All these modes of communication employs repeaters varying only in form because they are not operating on the same frequency. These are actually amplifiers which recovers the signal level lost on the way of transmission. It is something like a hotel on the way of tired travellers where one can rest and regain strenght to continue a certain journey.