Abstract: An all optical network for optical signal traffic has at least a first ring with at least one transmitter and one receiver. The first ring includes a plurality of network nodes. At least a first add/drop broadband coupler is coupled to the first ring. The broadband coupler includes an add port and a drop port to add and drop wavelengths to and or from the first ring, a pass-through direction and an add/drop direction. The first add/drop broadband coupler is configured to minimize a pass-through loss in the first ring and is positioned on the first ring.

Abstract: An all optical network for optical signal traffic provides at least a first ring with at least a first clockwise fiber, a second counter-clockwise fiber and a plurality of network nodes. Each node has at least a WDM transponder that with a line-side transmitter and a client-side receiver in a first direction, and a line-side receiver and a client-side transmitter in an opposing second direction. The line-side receiver includes a fixed or a tunable optical wavelength filter. At least a first add and a first drop broadband couplers are positioned on each fiber. Each coupler has first and second ports for through traffic and a third port for adding or dropping local traffic. The first add and first drop broadband couplers are configured to minimize a pass-through loss in each fiber. If there are multiple WDM transponders, their wavelengths are added to the ring either in series or in parallel. All wavelengths dropped from the ring are selected by each individual WDM transponder in a parallel or serial manner.

Abstract: An optical carrier notch filter includes an optical coupler with at least first, second and third ports. The first port is configured to receive an output that includes an optical carrier and interleaved optical single sideband signals. An optical bandpass filter is coupled to a port of the optical coupler. The optical bandpass filter separates the output into a transmitted signal that contains the optical carrier, and a reflected signal that includes the interleaved optical single sideband signals. The reflected signal is reflected from the optical bandpass filter to the third port of the optical coupler.

Abstract: An all optical network for optical signal traffic has at least a first ring with at least one transmitter and one receiver. The first ring includes a plurality of network nodes. At least a first add/drop broadband coupler is coupled to the first ring. The broadband coupler includes an add port and a drop port to add and drop wavelengths to and or from the first ring, a pass-through direction and an add/drop direction. The first add/drop broadband coupler is configured to minimize a pass-through loss in the first ring and is positioned on the first ring.

Abstract: A method and device for wavelength conversion, wavelength buffering and label/header swapping. A wavelength buffer is used to provide for in-band wavelength conversion in, for example, a dense wavelength division multiplexing communications system. The same device may be used for label/header swapping without wavelength conversion.