Raman amplification is a way of increasing the signal strength in an optical fiber. It is often used in a fiber that carries a signal for a long distance (such as in an undersea cable). Technically, it works by stimulating, in which a lower frequency 'signal' induces of a higher-frequency 'pump' photon in an optical medium in the nonlinear regime. As a result, another 'signal' photon is produced, with the surplus energy resonantly passed to the vibrational states of the.
[pdf] Ceramic ferrule is a core component used in fiber optic connectors, usually made of high-purity zirconia ceramic material. You cannot see them, but these tiny, engineered channels are the single most important part for aligning two optical fibers. A single micron of misalignment can bring a network to its knees. Rosen offer various shapes of ceramic ferrules.
[pdf] 
