Erbium-doped fiber amplifier
AssigneeAT&T Bell Laboratories
InventorsEmmanuel Desurvire, Clinton R. Giles, Jay R. Simpson, John L. Zyskind
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Abstract
This invention is a rare earth doped optical amplifier with increased gain and lowered pump thresholds. The amplifying scheme is based on a 3 level lasing system rather than the more prevalent 4 level lasing system. Additionally, the transmission mode of the optical fiber at the pump wavelength has a radius which is substantially equal to or greater than the radius of the distribution profile of the rare earth ions in the fiber amplifier core. With the inventive amplifier, a gain of 37 dB and a saturation power of 11.3 dBm has been obtained with only 54 mW of launch power at .lambda.=1.49 .mu.m.
Claims15
An optical amplifier comprising a single mode optical fiber having a core surrounded by a cladding, said core being doped with rare earth ions having a distribution profile, and
- means for generating a pump signal at a pump wavelength,
- said pump wavelength capable of coupling the ground state of the rare earth ions to an excited state which is an upper pump level of a three level lasing system having the ground state as the lower level of the lasing transition, said generating means being optically coupled to said optical fiber, the transmission mode of the optical fiber at the pump wavelength having a radius which is greater than the radius of the distribution profile of the rare earth ions in the core.
The optical amplifier of claim 11 characterized in that
- said core is a glass host.
The optical amplifier of claim 13 characterized in that
- said index raising dopants in core comprises Aluminum as a significant constituent.
A method of amplifying an optical signal comprising the steps of
- generating a pump signal at a pump wavelength,
- applying the pump signal to a single mode optical fiber having a core surrounded by a cladding, said core being doped with rare earth ions having a distribution profile and the pump wavelength being capable of coupling the ground state of the rare earth ions to an excited state which is an upper pump level of a three level lasing system having the ground state as the lower level of the lasing transition,
- causing the transmission mode of the optical fiber at the pump wavelength to have a radius which is greater than the radius of the distribution profile of the rare earth ions in the core, and
- applying to the single mode optical fiber an optical signal for amplification.
Dependencies are inferred from the claim text.