Abstract: The invention provides an optical device including a polarization diversity unit for receiving an input optical signal and producing two beams of light having a same polarization state therefrom, a beam swapping element disposed for receiving the first and second beams of light and for redirecting the two beams of light to a same overlapping area of a modulator, and a reflective surface for reflecting the two beams of light back to the polarization diversity unit where they are combined to form an output optical signal. The beam swapping element is designed and positioned such that the first and second beams of light swap positions upon reflection from the reflective surface and trace out the other's optical path. Advantageously, this optical arrangement essentially eliminates all PDL and PMD.

Abstract: Effective use of bandwidth resources such as wavelengths and paths are facilitated and the release of the fixed relationship of one client to one client is enabled by a WDM (Wavelength Division Multiplexed) network system executing automatic wavelength control using IP addresses. The WDM (Wavelength Division Multiplexed) network system includes an optical wavelength division multiplexed (WDM) transmission path, a plurality of sub-networks each accommodating a client, and a plurality of WDM nodes each corresponding to each of the plurality of sub-networks respectively and connected with the optical wavelength division multiplexed transmission path, the plurality of WDM nodes each including a wavelength converting unit for controlling oscillation frequencies depending on a destination address for which the communication destination is identified by an IP address and a cross-connecting unit for cross-connecting the route directed to an adjacent WDM node for connecting with the communication destination.

Abstract: A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.

Abstract: The abstract is amended to read, “An inventive method and apparatus is provided by a bidirectional optical 1×2 device formed by a cascade of three optical 2×2 devices. Each 2×2 device is bidirectional where optical signals propagate through the 2×2 device in the forward and backward directions simultaneously. The demultiplexing and multiplexing occur simultaneously to thereby perform bidirectional 1×2 optical demultiplexing and 2×1 optical multiplexing in the 1×2 device.

Abstract: Substantial reduction in crosstalk and improved scalability for supporting high channel counts in dense wavelength division multiplexed (DWDM) systems is achieved in an optical demultiplexer arrangement that partitions the total number of input optical channels into separate demultiplexer modules, demultiplexes smaller groups of optical channels in the separate demultiplexer modules, and filters the individual optical channels at the outputs of the separate demultiplexer modules. Partitioning the total number of channels into smaller demultiplexing groups and post-filtering a reduced number of demultipexed optical channels reduces the number of non-adjacent channels that can contribute to the total crosstalk level. The modularity of the optical demultiplexer arrangement results in smaller device footprints and smaller free spectral ranges associated with the demultiplexer modules. This modularity also allows for future system upgrades without redesign and without disruption to existing service.

Abstract: The optical hybrid device includes input optical fiber(s), output optical fiber(s), a lens, a broadband or passband filter, a movable mirror, and an actuator operative to move the mirror or the filter. Depending on a voltage applied to the actuator, the actuator selectively sets the mirror or filter to each of a plurality of positions, so that selected portion(s) of radiation from one or more input beams carried by the input optical fiber(s) are conveyed to the output optical fiber(s); whereby the device performs two or more of the functions of wavelength division multiplexing or demultiplexing, attenuation, switching, filtering and tapping functions.

Abstract: The present invention provides an improved wavelength division multiplexer (WDM) which utilizes a grating-based channel separator. The WDM includes an interleaved channel separator; and at least one channel separator optically coupled to the interleaved channel separator. The channel separator includes a grating. In a preferred embodiment, the channel separator also includes an alignment surface of the grating, a sleeve comprising a mount, the mount capable of contacting the grating, and an alignment plate coupled to an outer surface of the sleeve, wherein the alignment plate is capable of contacting the alignment surface of the grating. This grating-based channel separator affords a quick, easy, precise and reproducible positioning and alignment of grating block. Thus, the WDM is minimized in size while also reproducibly assembled with perfect alignment in a minimal amount of time.

Abstract: A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.

Abstract: A method for determining an optimal placement of wavelength converters in an optical network while optimizing bandwidth use in which a skeleton undirected graph of a WDM network is generated, a contraction graph is constructed from the skeleton undirected graph, and a minimum vertex cover of the contraction graph is determined.

Abstract: A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.

Abstract: A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.

Abstract: This invention provides a new architecture for a communication system between head-ends and end-users which expands bandwidth and reliability of the communication system. A mux-node receives communication signals from a head-end and forwards the received communication signals to one or more mini-fiber nodes. The connection to the head-end is via a small number of optical fibers and the connections to each of the mini-fiber nodes may be via one or more optical fibers that may provide full duplex communication. The head-end may communicate with the mux-node using digital or digital and analog signals. The mini-fiber nodes may combine the signals received from the head-end with loop-back signals used for local media access control prior to forwarding the signals to the end-users. Upstream data are received by the mini-fiber nodes and transmitted to the mux-node.

Abstract: A MAC master apparatus for executing a multi-point control protocol (MPCP) data in an optical line termination (OLT) of an Ethernet passive optical network (PON) is provided. The MPCP master apparatus includes a CPU interface unit, two or more memory arbitration control units, a SGA table memory, a RTT table memory, a static grant generation unit, a dynamic grant generation unit, a static grant queue, a dynamic grant queue, a sending message queue, a sending multiplexing unit, a time setting unit, a receiving window generation unit, an upstream grant queue, a received demultiplexing unit, a report queue and a received message queue. Therefore, any frame, including MPCP frames from/to the CPU can be sent or received, and a grant can be allocated statically according to a setting or dynamically according to a report from the ONUs.

Abstract: A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.

Abstract: A system S1 according to the invention comprises: a DVD unit 31 and a navigation unit 32, which generate video data; a ring-type network 1 in which a plurality of units are connected with one another in a ring shape and data is sent and received between the units adjacent to each other; and a branch network 2 which is connected through a gateway unit 3 being provided between the ring-type network 1 and the branch network 2, and including video display units 23, 24 and 25 which show the data from the DVD unit 31/navigation unit 32. By gateway unit 3, data is sent and received between the units adjacent to each other in the ring-type network 1 and video data generated in the DVD unit 31 and the navigation unit 32 is delivered to the branch network 2.

Abstract: A system and method is disclosed for providing high-speed, high capacity data communication over a Wave Division Multiplexing (WDM) network with an efficient re-routing capability. When all light channels between two nodes in the network are loaded with transmission jobs, a transmission traffic congestion is created. In order to avoid or alleviate the congestion, a new alternative route is needed. An alternative route is selected to direct the traffic away from the congested route, and further expand the channel capacity of the alternative route by encoding the light channels in the alternative route with orthogonal codes.

Abstract: High speed transport in a dense wavelength division multiplexed system is achieved by transmitting information supplied by multiple sources in a parallel format using a subset of the total number of optical channels in a wavelength division multiplexed signal as a parallel bus transmission group. In one illustrative embodiment, a selected number of optical channels, i.e., wavelength channels, in the wavelength division multiplexed signal are allocated to form a parallel bus transmission group, i.e., a wavelength bus. Information from one or more sources is supplied in a parallel format and then transmitted at the same transmission rate in each of the optical channels in the wavelength bus. When information from more than one source is to be transported, the information from each source is multiplexed into a parallel format.

Abstract: A communication system includes plural nodes interconnected with an optical transmission medium capable of carrying plural bands of optical channels. A device at each node is coupled to the medium for dropping one or more bands, adding one or more bands, and passively transmitting other bands such that a pair of nodes can communicate directly using a band common to the respective bands. One band of the bands associated with each of a first set of nodes overlaps with one band of the bands associated with each of a second set of nodes. Multiple overlapping bands provide a high level of wavelength termination diversity. An optical management bus system and method connects plural hybrid optical/electrical cables between transmission equipment and optical modules which connect to network fibers to provide a set of electrical connections that can be used to determine optical interconnections in an optical shelf configuration.

Abstract: A method and system deliver multiple-band broadcast services in a network such as a wavelength division multiplexed passive optical network. In the transmitter and/or receiver of such a system, filters are cascaded to stack data corresponding to different services within different free spectral frequency ranges of an optical transmission signal. Each filter is used to select a portion of a free spectral frequency range to be delivered to a user node. Each transmitter filter confines the output from spontaneous emission sources to a desired spectral region. The cascaded filters can also combine multiple spectra and/or separate combined broadcast spectrum. The method can also be used to partition the output from a broadband spectral source into different portions in the spectral domain.

Abstract: The object of the present invention is to provide a full-mesh optical wavelength division multiplexing transmission network device which is capable of exhibiting excellent communication quality and being mass produced, by reducing the accumulation number of coherent crosstalk lights, without any modification of constituent components constituting the conventional one. In the full-mesh optical wavelength division multiplexing transmission network device, provided is an N×N wavelength multi/demultiplexer having a periodic wavelength demultiplexing property in input/output combination, which performs input/output from/to first and second I/O port groups for optical signals and allows lightwaves traveling in opposite directions not to interfere with each other within the circut, thus reducing the accumulation number of coherent crosstalk lights in WDM wavelength lights and improving S/N of a received light.

Abstract: A monitoring system provides for monitoring the optical performance of a plurality of different channels of a fiber optic network, each channel having an associated channel wavelength. The system includes: means for generating a calibration signal including a plurality of stable calibration wavelengths; means for combining a tapped communication signal and the calibration signal to generate a combined signal; and a multi-channel monitoring device.

Abstract: An optical telecommunications network suitable for carrying broadcast and switched services. The network includes a wavelength division multiplexing (WDM) coupled to a waveguide grating router (WGR). In accordance with the invention, an adjacent input port is connected with the same optical content. Thus, its outputs are adjacent (or wrapped around). According, the optical power in each of the broadcast bands at the outputs remains the same but is reduced by a factor of two in power for each channel but occupying twice as many channels. This has the effect of increasing the SNR by a factor of two.

Abstract: A communication system includes plural nodes interconnected with an optical transmission medium capable of carrying plural bands of optical channels. A device at each node is coupled to the medium for dropping one or more bands, adding one or more bands, and passively transmitting other bands such that a pair of nodes can communicate directly using a band common to the respective bands. One band of the bands associated with each of a first set of nodes overlaps with one band of the bands associated with each of a second set of nodes. Multiple overlapping bands provide a high level of wavelength termination diversity. An optical management bus system and method connects plural hybrid optical/electrical cables between transmission equipment and optical modules which connect to network fibers to provide a set of electrical connections that can be used to determine optical interconnections in an optical shelf configuration.

Abstract: A low dispersion comb filter or interleaver assembly has a first interleaver element and a second interleaver element. The first interleaver element is configured so as to provide a dispersion vs. wavelength curve wherein each dispersion value thereof is approximately opposite in value to a dispersion value at the same wavelength for the second interleaver element, so as to mitigate net or total dispersion in the interleaver assembly.

Abstract: The present invention has an object to provide a WDM optical transmission system for effectively compensating such as wavelength dispersions of respective wavelength bands, by a simple constitution making use of a hybrid transmission path in case of transmitting a broadband WDM signal light containing a plurality of wavelength bands. To this end, wavelength dispersion characteristics of a hybrid transmission path utilizing a 1.3 &mgr;m zero-dispersion SMF and an RDF in the present WDM optical transmission system, are set such that compensation ratios of wavelength dispersion and dispersion slope become approximately 100% for a reference wavelength band which is one of a plurality of wavelength bands; and dispersion compensation fibers capable of compensating wavelength dispersions caused within the hybrid transmission path are inserted into propagation paths, respectively, within an optical amplifier, for the wavelength bands except for the reference wavelength band.

Abstract: A lightwave network data communications system having such an architecture that routing operation within a lightwave network is simplified, and a high-speed transfer process is attained in a large-scale basic network utilizing a wavelength division multiplexing (WDM) technology which accommodates internet traffics from a plurality of subscriber networks.

Abstract: A method and apparatus for multiplexing/de-multiplexing optical signals is disclosed. The method and apparatus are applicable to a range of optical multiplexing techniques including, but not limited to: wavelength division multiplexing (WDM), dense wavelength division multiplexing (DWDM) and frequency division multiple accessing (FDMA). The disclosed devices do not require active components. The disclosed devices may be implemented with fiber or fiberless optical communication systems including telecommunications systems. The devices may be used on their own or as part of a larger system such as a multi-stage mux/demux, an optical switch, or router. Additionally, the devices are passively thermally stabilized with the result that their tuning is substantially invariant across a wide temperature range. The optical device includes a linear polarizer, at least one wave plate and a beam displacer/combiner.

Abstract: A wireless communication system comprises a base station controller and a base station interface connected to the base station controller by a central optical fiber. The base station interface may include a flexible wavelength router. At least one base station is connected to the base station interface, and the central optical fiber carries at least one communication channel associated with an optical signal having one of a plurality of wavelengths. The base station interface selectively provides a communication path between the base station controller and at least one base station using at least one communication channel.

Abstract: An arrayed waveguide grating optical multiplexer/demultiplexer is provided to suppress a temperature depending characteristic of a center wavelength. The arrayed waveguide grating comprises at least one optical input waveguide, a first slab waveguide, an arrayed waveguide, a second slab waveguide, and a plurality of optical output waveguides. The first slab waveguide is separated on an cross separating plane which is intersected to a path of light passing through the first slab waveguide to constitute separated slab waveguides. A slide moving member is provided which may move at least one of these separated slab waveguides along the cross separating plane, depending upon the temperature. A front surface side of the waveguide forming region and a rear surface side of the substrate are sandwiched by a positional shift suppressing member such as a clip. The possition depressing the waveguide forming region by the clip is escaped from the optical axis of the separated slab waveguides.

Abstract: The invention provides an optical multiplexing and demultiplexing device using a two-dimensional photonic crystal, in which miniaturization and higher integration thereof can be achieved; an optical communication apparatus; and an optical communication system. The optical multiplexing and demultiplexing device of the present invention includes a substrate; and a plurality of slab layers provided on the substrate. The slab layers each have a two-dimensional photonic crystal structure, in which low refractive index regions are periodically arranged. In addition, the slab layers have line defects, provided in part of the periodical arrangement so as to function as a waveguide, and at least point defects formed in the respective periodic arrangements, the point defects capturing light having a specific wavelength and introducing it to the line defects or capturing light having a specific wavelength from the line defects and radiating it.

Abstract: An optical wavelength division multiplexing transmission network system having a star-topology network is disclosed, which comprises an arrayed-waveguide grating type multiplexing/demultiplexing circuit having N input ports and N output ports, and N transmitting/receiving apparatuses, each apparatus including a transmitter, receiver, demultiplexer, multiplexer, and N 2-input and 2-output optical path switching elements corresponding to N wavelengths, so as to cope with a damage to a transmitting or receiving portion corresponding to a specific wavelength. Each switching element is independently switched between first and second connective conditions.

Abstract: An optical frequency division multiplexing network includes first optical communication paths connected to terminals, respectively, a second optical communication path connected to the outside and a node composed of a selection unit for selecting signals having optical frequencies to be sent to the plurality of terminals, respectively, from signals transmitted through the second optical communication path in optical frequency division multiplexing, a conversion unit for converting the selected signals into signals having a single optical frequency and an output unit for producing the converted signals to the terminals through the first optical communication paths, respectively.