Abstract: An optical signal amplifier includes a Raman fiber amplifier and a semiconductor optical amplifier. The Raman fiber amplifier utilizes a portion of the pump radiation to amplify the optical signal resulting in an amplified optical signal and a residual pump radiation. The semiconductor optical amplifier receives the amplified signal and the residual pump radiation and utilizes the residual pump radiation to increase a saturation output power of the semiconductor optical amplifier while amplifying the amplified signal resulting in a twice amplified signal.

Abstract: An optical signal amplifier includes a first semiconductor optical amplifier having an input for receiving an optical signal, and an output, wherein the optical signal is amplified by the first semiconductor optical amplifier resulting in an amplified optical signal. The optical amplifier also includes an optical signal isolator having an input in optical communication with the output of the first semiconductor optical amplifier, and an output, wherein the optical signal isolator receives the amplified signal from the first semiconductor optical amplifier and allows for transmission of an optical signal in a single direction. The optical amplifier further includes a second semiconductor optical amplifier having an input for receiving the amplified optical signal from the optical signal isolator, and an output, wherein the amplified optical signal is amplified by the second semiconductor optical amplifier resulting in a twice amplified optical signal.

Abstract: A multi-wavelength Raman laser comprising a Raman fiber forming part of an optical ring, preferably most parts of which are formed by optical fiber. The ring includes a periodic filter selectively transmitting optical power at a number of equally spaced wavelengths corresponding to the wavelengths of the laser output. Radiation at the signal wavelengths propagating in one direction on the ring is tapped onto an output fiber. An optical isolator is formed either in the ring or fiber tapped into the ring to suppress radiation propagating in the reverse direction on the ring. A frequency shifter may be inserted into the loop to prevent power from concentrating in a single mode, thereby allowing wide band lasing. A band pass filter may be inserted into the loop to restrict the lasing band.

Abstract: An optical transmission system is provided comprising a thulium doped optical fiber, a light emitting pump device optically coupled to the thulium doped fiber, and a Raman amplifier fiber optically coupled to the thulium doped optical fiber. The light emitting pump device in combination with the thulium doped fiber generates a first amplification pump wavelength and the Raman amplifier receives the first amplification pump wavelength. The first pump wavelength amplifies an optical signal in the Raman amplifier, the Raman amplifier operating at a signal wavelength in the range of about 1530 nm to about 1625 nm.

Abstract: An optical signal amplifier includes a first semiconductor optical amplifier having an input for receiving an optical signal, and an output, wherein the optical signal is amplified by the first semiconductor optical amplifier resulting in an amplified optical signal. The optical amplifier also includes an optical signal isolator having an input in optical communication with the output of the first semiconductor optical amplifier, and an output, wherein the optical signal isolator receives the amplified signal from the first semiconductor optical amplifier and allows for transmission of an optical signal in a single direction. The optical amplifier further includes a second semiconductor optical amplifier having an input for receiving the amplified optical signal from the optical signal isolator, and an output, wherein the amplified optical signal is amplified by the second semiconductor optical amplifier resulting in a twice amplified optical signal.