Optical communication systems using raman repeaters and components therefor

An optical fiber communication system, said system comprising:

• an optical fiber transmission line including a core fabricated of a given material;
• means coupled to said optical fiber transmission line for introducing a plurality of information-bearing optical signals thereonto for transmission therealong, each of said information-bearing optical signals being carried on a distinct channel of predetermined wavelength;
• and
• means laterally coupled to said optical fiber transmission line at a predetermined location, downline of said means for introducing said information-bearing optical signals thereonto, for effecting collective optical amplification of all of said information-bearing optical signals, said amplification effecting means comprising at least one non-rotationally symmetric optical fiber tap for introducing optical energy onto said optical fiber transmission line at a preselected wavelength relative to the wavelengths of said information-bearing optical singals to collectively amplify all of said information-bearing optical signals by stimulated Raman scattering.

An optical fiber communication system, said system comprising:

• an optical fiber transmission line;
• means coupled to said optical fiber transmission line for introducing a plurality of information-bearing optical signals thereonto for transmission therealong, each of said information-bearing optical signals being carried on a distinct channel of predetermined wavelength;
• and
• means coupled to said optical fiber transmission line, downline of said means for introducing said information-bearing optical signals thereonto, for effecting collective optical amplification of all of said information-bearing optical signals, said means for effecting optical amplification comprising means for introducing optical energy onto said optical fiber transmission line at a preselected wavelength relative to the wavelengths of said information-bearing optical signals to collectively amplify all of said information-bearing optical signals by stimulated Raman scattering, said means for introducing optical energy into said optical fiber transmission line comprising a gain medium, a Fabry-Perot cavity, and an optical fiber coupling line wherein said gain medium is coupled to said Fabry-Perot cavity via said optical fiber coupling line.

An optical fiber communication system, said system comprising:

• an optical fiber transmission line;
• means coupled to said optical fiber transmission line for introducing a plurality of information-bearing optical signals thereonto for transmission therealong, said means for introducing information-bearing optical signals encoding information in the form of pulses having a given pulse width and wherein each of said information-bearing optical signals is carried on a distinct channel of predetermined wavelength;
• and
• means coupled to said optical fiber transmission line, downline of said means for introducing information-bearing optical signals, for effecting collective optical amplification of all of said information-bearing optical signals, said amplification effecting means comprising a plurality of pump sources for introducing optical energy onto said optical fiber transmission line at preselected wavelengths relative to the wavelengths of said information-bearing optical signals to collectively amplify all of said information-bearing optical signals by stimulated Raman scattering, the number of said pump sources being at least equal to the number of photons in an information pulse prior to amplification divided by 20 times the number of electromagnetic states within said given pulse width.

An optical fiber communication system, said system comprising:

• an optical fiber transmission line;
• means coupled to said optical fiber transmission line for introducing a plurality of information-bearing optical signals thereonto for transmission therealong, each of said information-bearing optical signals being carried on a distinct channel of predetermined wavelength, said means for introducing information-bearing optical signals comprising at least one signal generator including:
• (a) an elongated gain medium;
• (b) means for introducing energy into said gain medium to cause a population inversion of its atomic population such that said gain medium operates to spontaneously emit optical energy of different wavelengths in a random manner characteristic of its material composition;
• and
• (c) means external of said gain medium and optically coupled thereto for receiving optical energy therefrom, oscillating said energy at a preselected wavelength and feeding said energy at said preselected wavelength back through said medium for amplification thereby by stimulated emission whereby said signal generator operates to provide as an output a coherent electromagnetic wave at said preselected wavelength, said external means including a resonant fiber cavity structured to oscillate optical energy at said preselected wavelength and being substantially isolated from said gain medium to be relatively insensitive to conditions within said gain medium which would otherwise destabilize the wavelength output of said signal generator, and means coupled to said optical fiber transmission line at a predetermined location, downline of said means for introducing information-bearing optical signals thereonto, for effecting collective optical amplification of all of said information-bearing optical signals.

An optical fiber communication system, said system comprising:

• an optical fiber transmission line;
• means coupled to said optical fiber transmission line for introducing a plurality of information-bearing optical signals thereonto for transmission therealong, each of said information-bearing optical signals being carried on a distinct channel of predetermined wavelength, said means for introducing information-bearing optical signals comprising at least one signal generator including:
• (a) a light gain element including an elongated gain medium having a mirror at one end and means for energizing said gain medium;
• (b) a transfer optical fiber coupled to the other end of said gain medium;
• (c) an optical fiber Fabry-Perot resonant cavity laterally coupled to said transfer optical fiber and a portion of said optical fiber transmission line, said optical fiber Fabry-Perot resonant cavity being structured and arranged with respect to said transfer fiber and said gain medium to provide feedback to said gain medium via said transfer fiber so that said signal generator lases to provide as an output a coherent electromagnetic wave of predetermined wavelength and bandwidth and wherein said optical fiber Fabry-Perot resonant cavity is structured and arranged with respect to said portion of said fiber transmission line so that said output is coupled onto said fiber transmission line;
• and
• means coupled to said optical fiber transmission line at a predetermined location, downline of said information-bearing optical signal introducing means, for effecting collective optical amplification of all of said information-bearing optical signals.

An optical signal generator comprising:

• (a) an elongated gain medium;
• (b) means for introducing energy into said gain medium to cause a population inversion of its atomic population such that said gain medium operates to spontaneously emit optical energy of different wavelengths in a random manner characteristic of its material composition;
• and
• (c) means external of said gain medium and optically coupled thereto for receiving optical energy therefrom, oscillating said energy at a preselected wavelength and feeding said energy at said preselected wavelength back through said medium for amplification thereby by stimulated emission whereby said signal generator operates to provide as an output a coherent electromagnetic wave at said preselected wavelength, said external means including a resonant fiber cavity structured to oscillate optical energy at said preselected wavelength and being substantially isolated from said gain medium to be relatively insensitive to conditions within said gain medium which would otherwise destabilize the wavelength output of said signal generator, said external means further including a transfer fiber segment coupled to one end of said gain medium to receive optical energy therefrom and wherein said resonant fiber cavity is laterally coupled to said transfer fiber segment.

An optical signal generator comprising:

• (a) an elongated gain medium;
• (b) means for introducing energy into said gain medium to cause a population inversion of its atomic population such that said gain medium operates to spontaneously emit optical energy of different wavelengths in a random manner characteristic of its material composition;
• and
• (c) means external of said gain medium and optically coupled thereto for receiving optical energy therefrom, oscillating said energy at a preselected wavelength and feeding said energy at said preselected wavelength back through said medium for amplification thereby by stimulated emission whereby said signal generator operates to provide as an output a coherent electromagnetic wave at said preselected wavelength, said external means including a resonant fiber cavity structured to oscillate optical energy at said preselected wavelength and being substantially isolated from said gain medium to be relatively insensitive to conditions within said gain medium which would otherwise destabilize the wavelength output of said signal generator, said external means further including a transfer fiber coupled to one end of said gain medium to receive optical energy therefrom wherein said resonant fiber cavity is coupled to said transfer fiber, a second transfer fiber coupled to the other end of said gain medium to receive optical energy therefrom, and a second resonant fiber cavity coupled to said second transfer fiber.

An optical signal generator comprising:

• (a) an elongated gain medium;
• (b) means for introducing energy into said gain medium to cause a population inversion of its atomic population such that said gain medium operates to spontaneously emit optical energy of different wavelengths in a random manner characteristic of its material composition;
• and
• (c) means external of said gain medium and optically coupled thereto for receiving optical energy therefrom, oscillating said energy at a preselected wavelength and feeding said energy at said preselected wavelength back through said medium for amplification thereby by stimulated emission whereby said signal generator operates to provide as an output a coherent electromagnetic wave at said preselected wavelength said external means including a resonant fiber cavity structured to oscillate optical energy at said preselected wavelength and being substantially isolated from said gain medium to be relatively insensitive to conditions within said gain medium which would otherwise destabilize the wavelength output of said signal generator, and means for modulating output of said signal generator so that said output has at least two distinct wavelengths, said modulating means including a piezoelectric crystal mechanically coupled to said resonant fiber cavity.

An optical signal generator for use with an optical fiber transmission line, said signal generator comprising:

• (a) a light gain element including an elongated gain medium having a mirror at one end and means for energizing said gain medium;
• (b) a transfer optical fiber coupled to the other end of said gain medium;
• and
• (c) an optical fiber Fabry-Perot resonant cavity laterally coupled to said transfer optical fiber and structured for coupling with a portion of an optical fiber transmission line, said optical Fabry-Perot resonant cavity fiber being structured and arranged with respect to said transfer fiber and said gain medium to provide feedback to said gain medium via said transfer fiber so that said signal generator lases to provide as an output a coherent electromagnetic wave of predetermined wavelength and bandwidth and wherein said optical fiber Fabry-Perot resonant cavity is structured and arranged to be coupled to a portion of the fiber transmission line to introduce said output onto said fiber transmission line.