Raman amplifier with gain enhancement from optical filtering

A fiber Raman amplifier comprising

• a section of single mode fiber comprising a core for producing stimulated emission of light via Raman scattering within a predetermined band of wavelengths, including at least one signal wavelength λS, when pumped with at least one optical pump signal at a predetermined wavelength λP;
• a pump source for producing said least one optical pump signal, said pump source at a predetermined location remote from said section of single mode fiber;
• a first arrangement for coupling at least one input optical signal to the section of single mode fiber;
• a second arrangement for coupling at least one optical pump signal to said section of single mode fiber;
• and
• a high pass optical filter exhibiting a cut-off frequency immediately below that of the lowest frequency pump, said high pass filter disposed between said pump source and said section of single mode fiber.

An optical transmission system in an environment including an optical transmitter for providing at least one input optical signal at a predetermined wavelength λS and an optical receiver for receiving said at least one input optical signal the optical transmission system comprising

• an optical signal path, disposed between said optical transmitter and said optical receiver, said optical signal path including at least one optical amplifier arrangement comprising
• a section of single mode fiber comprising a core for producing stimulated emission of light via Raman scattering within a predetermined band of wavelengths, including at least said signal wavelength λS, when pumped with at least one optical signal at a predetermined wavelength λP;
• a first arrangement for coupling said at least one input optical signal from said optical signal path to the section of single mode fiber;
• a second arrangement for coupling at least one optical pump signal to said section of single mode fiber;
• and
• a high pass optical filter exhibiting a cut-off frequency immediately below that of the lowest frequency input signal, said high pass filter disposed along said section of single mode fiber.

An optical transmission system in an environment including an optical transmitter for providing at least one input optical signal at a predetermined wavelength λS and an optical receiver for receiving said at least one input optical signal, the optical transmission system comprising

• an optical signal path, disposed between said optical transmitter and said optical receiver, said optical signal path including at least one optical amplifier arrangement comprising
• a section of single mode fiber comprising a core for producing stimulated emission of light via Raman scattering within a predetermined band of wavelengths, including at least said signal wavelength λS, when pumped with at least one optical signal at a predetermined wavelength λP;
• a remote pump source for providing at least one optical pump, said remote pump disposed at a predetermined distance from said section of single mode fiber;
• a first arrangement for coupling said at least one input optical signal from said optical signal path to the section of single mode fiber;
• a second arrangement for coupling said remote pump source to said section of single mode fiber;
• and
• a high pass optical filter exhibiting a cut-off frequency immediately below that of the lowest frequency optical pump, said high pass filter disposed along said optical transmission path between said remote pump and said section of single mode fiber.