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 at least two sections of optical fiber;
• providing an amplification signal propagating in a reverse direction to amplify the optical signal using a pump light emitting device optically coupled to said optical fiber;
• and
• preventing pre-selected wavelengths from propagating in a reverse direction using a device positioned between said at least two sections of optical fiber.

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

• at least two sections of optical transmission fiber;
• a directional wavelength selector positioned between said at least two sections of optical fiber;
• and
• a pump light emitting device optically coupled to said optical fiber,
• wherein said directional wavelength selector prevents pre-selected 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:

• at least two sections of optical fiber wherein at least one section of said optical fiber comprises small effective area optical fiber;
• a pump light emitting device optically coupled to one of said at least two sections of optical fiber wherein said pump light emitting device provides an amplification signal along said optical fiber;
• and
• a directional wavelength selector positioned between said at least two sections of optical fiber wherein said directional wavelength selector allows said signal wavelengths 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:

• at least two sections of optical transmission fiber;
• a pump light emitting device optically coupled to one of said at least two sections of optical fiber wherein said pump light emitting device provides an amplification signal along said optical fiber;
• and
• an optical circulator positioned between said at least two sections 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 at least 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;
• and
• a Raman pump light emitting device optically coupled to said optical fiber for generating an amplification signal,
• 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.