Enabler of large raman gain on small effective area fibers

A method of transporting an optical signal comprising the steps of:

• transporting an optical signal via an optical fiber comprising a first section and a second section of optical fiber;
• providing a first amplification signal propagating in a reverse direction to amplify the optical signal using a first pump light emitting device optically coupled to said first section of optical fiber;
• preventing pre-selected wavelengths of the optical signal from propagating in a reverse direction using a device positioned between said first section and second section of optical fiber, and
• providing a second amplification signal propagating in a reverse direction to amplify the optical signal using second pump light emitting device optically coupled to said second section of optical fiber, wherein the amplification signals from the first and second pump light emitting devices are at different wavelengths and said second section receives different wavelength amplification signals than said first section.

A optical transmission system including optical fiber, the optical transmission system transmitting in a predetermined wavelength range, the system comprising:

• a first section and a second section of optical fiber;
• a directional wavelength elector positioned between said first and second section of optical fiber;
• a first pump light emitting device optically coupled to said first section of optical fiber that provides pump light in he reverse direction;
• and
• a second pump light emitting device optically coupled to said second section of optical fiber that provides pump light in the reverse direction, wherein the pump light from the first and second pump light emitting devices are at different wavelengths and said second section receives different wavelength pump light than said first section,
• wherein said directional wavelength selector prevents pre-selected optical signal wavelengths from propagating in a reverse direction.

An optical transmission system including optical fiber, the optical transmission system transmitting optical signals in a predetermined wavelength range comprising:

• a first section and a second section of optical fiber wherein at least one of the first and second section of said optical fiber comprises small effective area optical fiber;
• a first pump light emitting device optically coupled to said first section of optical fiber that provides pump light in a reverse direction, wherein said first pump light emitting device provides an amplification signal along said optical fiber;
• a second pump light emitting device optically coupled to said second section of optical fiber that provides pump light in the reverse direction, wherein the pump light from the first and second pump light emitting devices are at different wavelengths and said second section receives different wavelength pump light than said first section;
• and
• a directional wavelength selector positioned between said first and second section of optical fiber wherein said directional wavelength selector allows said optical signals to only propagate substantially in the forward direction and allows said amplification signal to propagate in the reverse direction.

An apparatus for transporting an optical signal comprising:

• a first section and a second section of optical fiber;
• a first pump light emitting device optically coupled to said first section of optical fiber that provides pump light in a reverse direction, wherein said pump light emitting device provides an amplification signal along said optical fiber;
• a second pump light emitting device optically coupled to said second section of optical fiber that provides pump light in the reverse direction, wherein the pump light from the first and second pump light emitting devices are at different wavelengths and said second section receives different wavelength pump light than said first section;
• and
• an optical circulator positioned between said first and second section of optical fiber comprising at least three ports Tx, Rx, and Lx wherein:
• signals entering port Rx circulate to port Lx,
• signals entering port Lx circulate to port Tx, and
• signals entering port Tx circulate to port Rx;
• and
• a wave cancellation device positioned at said Lx port of said optical circulator wherein said wave cancellation device reflects said amplification signal back into port Lx and substantially does not reflect other signals emerging from port Lx.

A Raman optical signal amplifier comprising:

• an optical fiber comprising a first section of optical fiber and a second section of optical fiber;
• a directional wavelength selector positioned between said first and second sections of optical fiber wherein said directional wavelength selector allows signal wavelengths to propagate in a forward direction and selectively blocks wavelengths propagating in a reverse direction;
• a first Raman pump light emitting device optically coupled to said first section of optical fiber for generating a first amplification signal in the reverse direction;
• and
• a second Raman pump light emitting device optically coupled to said second section of optical fiber for generating a second amplification signal in the reverse direction, wherein the pump light from the first and second Raman pump light emitting devices are at different wavelengths and said second section receives different wavelength pump light than said first section,
• wherein said first section of optical fiber comprises optical fiber with an effective area less than 40 μm2,
• wherein said second section of optical fiber comprises optical fiber with an effective area greater than 50 μm2.