Improved optical network configurations are described incorporating ROADM component structures that are compatible with simplified user transceivers. The ROADM component structures generally include a reconfigurable optical add/drop multiplexer component comprising a multicast switch (MCS), a tunable optical filter (TOF), optical amplifiers, and user side ports. The MCS can be connected to network side optical conduits, while the TOF can be connected by optical conduits to the MCS and to the optical amplifiers by a distinct optical port of the TOF. The user side ports can be connected to the optical amplifiers and to light conduits of a user transceiver. In some embodiments, the MCS and the TOF can be planar optical circuits, and the optical amplifiers can be configured for single wavelength amplification. The improved ROADM component structures can be used for add-side components, drop-side components, or bothand provide for energy efficiency and/or improved device layout.

An apparatus includes a first input port, a first switch, and a second switch. The first switch and the second input port are in optical communication with the first input port. The apparatus also includes a second input port, a third switch, and a fourth switch. The third switch and the fourth switch are in optical communication with the second input port. Each switch is switchable between a first state to pass optical signals and a second state to block optical signals. The apparatus also includes a first combiner in optical communication with the first input port via the first switch and the second input port via the third switch. The apparatus also includes a second combiner in optical communication with the first input port via the second switch and the second input port via the fourth switch.

An apparatus includes a first reconfigurable optical add/drop multiplexer (ROADM) to receive a first optical signal and a second ROADM to receive a second optical signal. The apparatus also includes a reconfigurable optical switch that includes a first switch, switchable between a first state and a second state, to transmit the first optical signal at the first state and block the first optical signal at the second state. The reconfigurable optical switch also includes a second switch, switchable between the first state and the second state, to transmit the second optical signal at the first state and block the second optical signal at the second state. The reconfigurable optical switch also includes an output port to transmit an output signal that is a sum of possible optical signals transmitted through the first switch and the second switch.

It is made possible to accommodate a plurality of services and transmit each of the accommodated services to a corresponding transmission device. An optical transmitter according to an exemplary aspect of the present invention includes sub-carrier adjusting means for outputting sub-carriers to a plurality of output ports according to a control signal; encoding processing means for mapping client data on a plurality of output lanes according to the control signal; a plurality of modulation means for modulating the sub-carriers inputted through the output ports by client data inputted through the output lanes and outputting modulated signals; and control means for generating and outputting the control signal based on transmission information.

An optical transceiver is provided with an optical front end for receiving signal light comprising an optical sub-channel, and for providing an electrical signal based on the signal light; a light source optically coupled to the optical front end for providing local oscillator light thereto for mixing with the signal light; an electro-optical modulator coupled to the light source for receiving output light therefrom and for modulating the output light with digital information to obtain modulated light; and a signal processor operably coupled to the optical front end. The signal processor is configured for processing the electrical signal to obtain a frequency offset of the sub-channel; and adjusting an optical frequency of the modulated light based on the frequency offset. When applied to a multiple-access environment, this may allow access nodes to generate optical sub-channels in the uplink direction using the downlink optical signal as an optical frequency reference.

A method of nonblocking optical switching includes guiding a first optical beam from a first input to a first output via a first path through an optical switching fabric. The first path traverses a phase shifter disposed between a pair of cascaded Mach-Zehnder interferometers. The method also includes receiving a second optical beam for a second path intersecting with the first path through the optical switching fabric. The method also includes moving the first optical beam from the first path to a third path connecting the first input to the first output without intersecting the second path. The method also includes shifting a phase of the first optical beam, with the phase shifter, while moving the first optical beam from the first path to the third path to prevent the first optical beam from interfering with the second optical beam.

An optical device includes a plurality of optical input ports, a plurality of optical output ports, a wavelength dispersion arrangement and at least one optical beam steering arrangement. The plurality of optical input ports is configured to receive optical beams each having a plurality of wavelength components. The wavelength dispersion arrangement receives the optical beams and spatially separates each of the optical beams into a plurality of wavelengths components. The optical beam steering arrangement has a first region onto which the spatially separated wavelength components are directed and a second region onto which any subset of the plurality of wavelength components of each of the optical beams is selectively directed after the wavelength components in each of the subsets are spatially recombined with one another. The optical beam steering arrangement selectively directs each of subset of the plurality of wavelength components to a different one of the optical output ports.

An intersecting splitter configured so that the branching ratio of each optical splitter differs in accordance with the difference in the number of intersections in each branched waveguide. The branching ratios (totaling 100%) of the optical splitters are adjusted so that the branching ratios on the high side as to the number of intersections is high in comparison with the branching ratios on the low side as to the number of intersections, and it is thereby possible to level the total loss.

In one embodiment, each of the output/input ports of each one of a plurality of optical splitters is connected to one of a plurality of optical switches by means of optical fibers without any fusion splicing in a majority of the optical fibers, and each of the input/output ports of each one of the switches is connected to one of the optical splitters by means of the optical fibers without any fusion splicing in a majority of the optical fibers. Each of the output/input ports of each one of the optical splitters may be directly connected to the ferrule and one of the input/output ports of one of the switches by the optical fibers. The optical splitters may be implemented in at least one planar lightwave circuit (PLC) chip. Optionally, at least one fiber holder defining a plurality of channels therein may be used to hold the optical fibers each of which is aligned with a corresponding output/input port of one of the optical splitters.

An optical line terminal (OLT) and an optical network unit (ONU) configured to generate a plurality of fragments by fragmenting a media access control (MAC) frame and to transmit the plurality of generated fragments, when a length of the MAC frame is greater than or equal to a maximum transmission unit (MTU).