Fujitsu Corporation

Daniel Bihon

Tadashi Ikeuchi

Youichi Akasaka

Eric Koopferstock

Richard Colter

Paparao Palacharla

Olga I Vassilieva

Ashwin Anil Gumaste

A low-noise amplifier includes a gain medium and two or more amplifier stages. Each amplifier stage includes an optical filter to pass all wavelengths of a respective input optical signal in a given propagation direction over the gain medium and reflect wavelengths above a respective threshold wavelength received in the opposite direction, and a respective Raman pump to inject a pump light centered at a wavelength lower than the threshold wavelength onto the gain medium for transmission in the given direction. A first amplifier stage outputs a first combined optical signal including all wavelengths of the respective input optical signal and a pump light injected by the respective Raman pump. The second amplifier stage receives the first combined optical signal as its input and outputs a second combined optical signal including all wavelengths of the first combined optical signal and a pump light injected by the respective Raman pump.

Low-noise Raman amplifier

Phase modulation of an output optical signal from a phase-sensitive amplifier may be used to perform phase adjustment for optimal phase-sensitive amplification. Specifically, when the optical pump is phase modulated to suppress SBS, a second phase modulator may be used to counter dither the first phase modulator. Both phase modulators may be controlled by a phase shifter. Intensity modulation of the output optical signal may also be performed to reduce noise. In this manner, the OSNR of the output optical signal may be increased.

Optical phase-sensitive amplifier with signal noise removal

Methods and systems may implement a credit based approach for optimizing optical transmission and calculating optical paths in optical networks.

Credit based approach to calculating optical paths

Credit based approach to optimizing optical transmission

According to particular embodiments, reducing cross-phase modulation includes sending instructions to a phase modulation array comprising channel pixel sets that modulate phases of channels. The channel pixel sets comprise a first channel pixel set that modulates a first phase of a first channel and a second channel pixel set that modulates a second phase of a second channel that uses a phase modulation format. The first channel pixel set is instructed to modulate the first phase at a first constant phase. The second channel pixel set is instructed to modulate the second phase at a second constant phase different from the first constant phase in order to create a group delay between the first channel and the second channel.

Reducing cross-phase modulation using group delay

A system and method for modularly scalable architecture for optical networks are provided. In one embodiment, a node for an optical network comprises a plurality of in-line switches connected to an optical ring and operable in a first state to both pass an optical signal received from the optical ring to an associated coupler and pass an optical signal received from the associated coupler to the optical ring. The optical signal carries traffic in a plurality of channels. A drop coupler is coupled to a first in-line switch and is operable to receive an optical signal from the in-line switch where the switch is in the first state, pass a first copy of the optical signal back to the in-line switch for passing to the optical ring, and drop a second copy of the optical signal to a distributing element. The distributing element is operable to receive the second copy and pass traffic in one or more channels of the second copy. A filter is operable to reject one or more channels of the first copy to generate a passthrough signal. A combining element is operable to receive traffic in one or more channels to be added to the optical ring and combine the received traffic to generate an add signal. An add coupler is coupled to a second in-line switch and is operable to receive the passthrough signal from the second in-line switch when the switch is in the first state, add the add signal to the passthrough signal to generate a combined signal, and pass the combined signal to the second in-line switch for passing to the optical ring.

Growing community of inventors

Allen, TX, United States of America

Daniel Bihon