Abstract: This disclosure provides systems, methods, and apparatus for improving spectral efficiency of a communication system. The communication system can include a transmitter, a receiver and a communication link for communicating data between the transmitter and the receiver. The transmitter can employ a multi-carrier technique to transmit data to the receiver. The transmitter can generate a plurality of carrier signals using a receiver-side comb generator, one of which is sent to the transmitter as a pilot carrier signal combined with modulated carrier signals over an optical link. At the receiver the receiver-side comb generator uses the pilot carrier signal to generate a plurality of receiver-side carrier signals, which are used for detecting the modulated carrier signals. As the phase noise in the modulated carrier signals and the phase noise in the receiver-side carrier signals have the same characteristics, the phase noise is cancelled at the receiver, resulting in improved detection.

Abstract: This disclosure provides systems, methods, and apparatus for improving spectral efficiency of a communication system. The communication system can include a transmitter, a receiver and a communication link for communicating data between the transmitter and the receiver. The transmitter can employ a multi-carrier technique to transmit data to the receiver. The transmitter can generate a plurality of carrier signals using a receiver-side comb generator, one of which is sent to the transmitter as a pilot carrier signal combined with modulated carrier signals over an optical link. At the receiver the receiver-side comb generator uses the pilot carrier signal to generate a plurality of receiver-side carrier signals, which are used for detecting the modulated carrier signals. As the phase noise in the modulated carrier signals and the phase noise in the receiver-side carrier signals have the same characteristics, the phase noise is cancelled at the receiver, resulting in improved detection.

Abstract: Methods, mediums and systems described herein determine real-time in-service OSNR measurement without disrupting or turning off one or more channels of the network. An OSNR monitor described herein may be integrated with existing optical line systems. The OSNR measurements performed by the OSNR monitors are independent of the modulation format and thus, may work with all phase formats, amplitude format or a combination thereof. The real-time in-service OSNR data may be used to perform global network optimization to determine the optimal routing and data rate in the optical network. The OSNR data may be used to establish protection and restoration paths for network resiliency and to maximize data throughput.

Abstract: An optical add-drop multiplexer including a first filter filtering a first band of wavelengths of a communication spectrum for a first communication segment and a second filter filtering a second band of wavelengths of the communication spectrum for a second communication segment. The second band of wavelengths overlaps the first band of wavelengths in an overlap band of wavelengths. The overlap band may have a variable size. The first band of wavelengths includes a first fraction of the overlap band of wavelengths for the first communication segment and the second band of wavelengths includes a remaining fraction the overlap band of wavelengths for the second communication segment.

Abstract: A packet switch/router including a first stage switch fabric receiving an electrical signal, a mid-stage buffer receiving and storing the electrical signal from the first stage switch fabric, and a second stage switch fabric receiving the electrical signal from the mid-stage buffer. Each switch fabric includes N layers of N×N arrayed waveguide gratings (AWGs), and each AWG has ingress ports and egress ports. A wavelength tunable device, such as a tunable laser, communicates with a source ingress port of an AWG and converts the received electrical signal to an optical signal having a wavelength selected for routing a packet from the source ingress port to a target egress port of the arrayed waveguide grating. A photoreceiver, such as a burst-mode photoreceiver, receives the propagated optical signal from the target egress port and converts the optical signal to the electrical signal.

Abstract: An optical add-drop multiplexer including a first filter filtering a first band of wavelengths of a communication spectrum for a first communication segment and a second filter filtering a second band of wavelengths of the communication spectrum for a second communication segment. The second band of wavelengths overlaps the first band of wavelengths in an overlap band of wavelengths. The overlap band may have a variable size. The first band of wavelengths includes a first fraction of the overlap band of wavelengths for the first communication segment and the second band of wavelengths includes a remaining fraction the overlap band of wavelengths for the second communication segment.

Abstract: A packet switch/router including a first stage switch fabric receiving an electrical signal, a mid-stage buffer receiving and storing the electrical signal from the first stage switch fabric, and a second stage switch fabric receiving the electrical signal from the mid-stage buffer. Each switch fabric includes N layers of N×N arrayed waveguide gratings (AWGs), and each AWG has ingress ports and egress ports. A wavelength tunable device, such as a tunable laser, communicates with a source ingress port of an AWG and converts the received electrical signal to an optical signal having a wavelength selected for routing a packet from the source ingress port to a target egress port of the arrayed waveguide grating. A photoreceiver, such as a burst-mode photoreceiver, receives the propagated optical signal from the target egress port and converts the optical signal to the electrical signal.