A gain-clamped semiconductor optical amplifier uses the Raman amplification principle.
A Raman amplifier and a gain clamped semiconductor optical amplifier are integrated
onto an optical amplifier module. The gain-clamped semiconductor optical amplifier
includes: an optical fiber having Raman gain characteristics; and a gain-clamped
semiconductor optical amplifier for providing a pumping light to the optical fiber
by laser oscillation using a distributed Bragg reflector (DBR) lattice. The DBR
has input and output terminals asymmetrical to each other, at least for amplifying
a signal light Raman-amplified by the optical fiber.