EDFA optical amplifier rises as a preferable option for signal amplification method for DWDM systems, owing to its low noise and insensitive to signal polarization.
An SOA (Semiconductor Optical Amplifier) is a semiconductor element that amplifies light. Antireflective processing is applied on both facets of a semiconductor laser to eliminate the resonator structure. When light enters from outside the semiconductor, the light is amplified by stimulated emission.
A Raman amplifier is an optical amplifier based on Raman gain, which results from the effect of stimulated Raman scattering. The Raman-active medium is often an optical fiber, although it can also be a bulk crystal, a waveguide in a photonic integrated circuit, or a cell with a gas or liquid medium
Erbium-Doped Fiber Amplifier (EDFA) is an optical amplifier used in the C-band and L-band, where the loss of telecom optical fibers becomes lowest in the entire optical telecommunication wavelength bands.