Overlapping Spectrum Amplification

An optical system comprising:

• a splitter configured to:
• receive an optical signal having a first frequency band and a second frequency band;
• and
• split the optical signal into a first split signal having the first frequency band and a second split signal having the second frequency band, the splitting resulting in a band gap between the first wavelength band and the second wavelength band;
• a gap compensator optically coupled to the splitter and configured to delay the first split signal by a threshold period of time relative to the second split signal, wherein the gap compensator comprises:
• a first erbium doped fiber optically coupled to the splitter and configured to amplify the first split signal by a first gain;
• a single mode fiber optically coupled to the first erbium doped fiber and having a length sized to impart the delay in the first split signal by the threshold period of time;
• and
• a second erbium doped fiber optically coupled to the splitter and configured to amplify the second split signal by a second gain;
• and
• a combiner optically coupled to the gap compensator and configured to combine the delayed first split signal and the second split signal, resulting in a combined signal having the first wavelength band and the second wavelength band without the band gap therebetween, wherein a path difference between the delayed first split signal and the second split signal is within a threshold multipath interference compensation range,
• wherein the combined signal has a power determined as:
• SignalOut(λ, t)=SignalIn(λ, t)* [Filter(λ)2*Gainc(λ, Lengthc/cLight)* TDelay(LengthL/cLight−Lengthc/cLight)+(1−Filter(λ))2*Gainλ, Lengthc/cLight)]
• wherein SignalOut(λ, t) is the power of the combined signal, SignalIn(λ, t) is the power of the received signal as a function of a given wavelength λ and time t, Filter(λ) is a filter coefficient based on the given wavelength λ, Gainc is a first gain of the first erbium doped fiber, GainL is a second gain of the second erbium doped fiber, Lengthc is a length of the first erbium doped fiber, LengthL is a length of the second erbium doped fiber, cLight is the speed of light in fiber, and TDelay is the time delay.

An optical system comprising:

• a splitter configured to:
• receive an optical signal having a first frequency band and a second frequency band;
• and
• split the optical signal into a first split signal having the first frequency band and a second split signal having the second frequency band, the splitting resulting in a band gap between the first wavelength band and the second wavelength band;
• a gap compensator optically coupled to the splitter and configured to delay the first split signal by a threshold period of time relative to the second split signal;
• a combiner optically coupled to the gap compensator and configured to combine the delayed first split signal and the second split signal, resulting in a combined signal having the first wavelength band and the second wavelength band without the band gap therebetween;
• and
• a digital coherent receiver coupled to the combiner, the digital coherent receiver configured to map an optical field of the optical signal into electronic signals corresponding to phase and quadrature field components,
• wherein a path difference between the delayed first split signal and the second split signal is within a threshold multipath interference compensation range, and
• wherein the digital coherent receiver comprises a digital signal processor comprising a multipath interference compensator configured to resolve a time delay between the first polarized signal and the second polarized signal caused by the path difference between the delayed first split signal and the second split signal.

An optical system comprising:

• a splitter configured to:
• receive an optical signal having a first frequency band and a second frequency band;
• and
• split the optical signal into a first split signal having the first frequency band and a second split signal having the second frequency band, the splitting resulting in a band gap between the first wavelength band and the second wavelength band;
• a gap compensator optically coupled to the splitter and configured to delay the first split signal by a threshold period of time relative to the second split signal, the gap compensator comprising:
• a first erbium doped fiber optically coupled to the splitter and configured to amplify the first split signal by a first gain, the first erbium doped fiber having a first length;
• a second erbium doped fiber optically coupled to the splitter and configured to amplify the second split signal by a second gain, the second erbium doped fiber having a second length greater than the first length;
• and
• a single mode fiber optically coupled to the first erbium doped fiber and having a third length sized to impart the delay in the first split signal by the threshold period of time;
• and
• a combiner optically coupled to the gap compensator and configured to combine the delayed first split signal and the second split signal, resulting in a combined signal having the first wavelength band and the second wavelength band without the band gap therebetween, wherein a path difference between the delayed first split signal and the second split signal is within a threshold multipath interference compensation range;
• and
• a digital coherent receiver coupled to the combiner, the digital coherent receiver configured to map an optical field of the optical signal into electronic signals corresponding to phase and quadrature field components, the digital coherent receiver comprising a digital signal processor configured to resolve a time delay between the first polarized signal and the second polarized signal caused by the path difference between the delayed first split signal and the second split signal.