I am doing a presenatition on optical amplifier, and that would be later for work, how or when should I decide to use the amplifier ,around which distances could be used ? if this question doesn't refer to this forum where should I ask it ?
Standard SFP modules are commonly available for up to 100 or 120 km reach, so anything beyond that requires either special transceivers and careful engineering, or intermediate amplifiers.
You can't pump arbitrary levels of power into a fiber as there's only so much it can carry. Even then, a tiny fault may cause the fiber to burn backwards from the fault to the transmitter. (Since that can be very costly, high-power fibers are usually protected by logic circuitry that shuts down the power in the case of a signal loss on the far side, limiting the damage.)
Regarding estimated distances for each cable type or wavelength - actually, there's only one cable standard type and one wavelength (or WDM band) for long distance. Using other lambdas or cable types may require regeneration well before the mentioned reach (e.g. 10GBASE-SR w/ 850 nm over OM2 fiber has a reach of just 80 meters). You should be aware that there are a few other parameters limiting the reach of fiber than just amplitude.