Relative intensity noise (RIN) reduction in fiber-based raman amplifier systems
AssigneeFitel USA Corp.
InventorMarc D. Mermelstein
Life of this patent
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Abstract
An arrangement for reducing the effects of pump signal relative intensity noise (RIN) in a Raman fiber amplifier. A portion of the output from a pump laser source is applied as an input to a compensating, lower power laser module, where fluctuations in the output power of the pump laser are used to control the bias current applied as an input to the compensating laser such that as the pump power increases, the bias current (and lower power laser output) decreases; conversely, as the pump power decreases, the bias current applied as an input to the compensating laser will be increased. The result is a relatively flat gain as seen by the information signal, thus minimizing the transfer of relative intensity noise from the pump to the signal.
Claims14
An arrangement for reducing the effects of relative intensity noise (RIN) associated with an optical pump source in a Raman fiber amplifier, the arrangement comprising:
- a pump source for supplying a first optical pump signal capable of generating gain in an optical information signal propagating along the Raman fiber amplifier;
- a compensating, low power laser source for providing a second optical pump signal input to said Raman fiber amplifier;
- and
- a power monitoring arrangement responsive to a portion of the output signal from the pump source for generating therefrom an intensity-modulated bias current input for said compensating, low power laser, said low power laser thus exhibiting an output power controlled by said modulating bias current to stabilize the net gain provided to the optical information signal propagating along said Raman fiber amplifier and minimize the effects of RIN associated with said pump source.
An arrangement for reducing relative intensity noise in an optical pump source for a Raman fiber amplifier, the arrangement comprising
- an optical tap for removing a portion of the output signal from the optical pump source to form a tapped-off monitoring signal;
- an optical signal splitter responsive to the tapped-off monitoring signal to form a first optical monitoring signal and a second optical monitoring signal;
- an optical-to-electrical converter responsive to the first optical monitoring signal to generate an electrical bias current representative of the power fluctuations present in the output signal from the optical pump source;
- a variable optical attenuator responsive to both the second optical monitoring signal and the electrical bias current to generate as an output a compensation signal representative of power fluctuations in the optical pump output signal;
- and
- a signal coupler for combining the pump source output signal and the compensation signal to form a stabilized optical pump signal with reduced relative intensity noise.
Dependencies are inferred from the claim text.