512results about "Optical mode multiplex systems" patented technology

Methods and apparatus for creating, transmitting and receiving ultra-wideband pulses through wire media are presented. One embodiment of the present invention transmits ultra-wideband pulses that occupy radio frequencies that are not used by other electromagnetic signals present in a wire medium of interest. Other embodiments of the invention may create, transmit, and receive ultra-wideband pulses that use radio frequency(s) that are not used by other signals present on wire media within a wire network of interest. This Abstract is provided for the sole purpose of complying with the Abstract requirement rules that allow a reader to quickly ascertain the subject matter of the disclosure contained herein. This Abstract is submitted with the explicit understanding that it will not be used to interpret or to limit the scope or the meaning of the claims.

A visible ray communication system and method that improve transmission rate and remove an influence of inter-color interference to improve the communication quality. A transmission apparatus included in the visible ray communication system allocates each carrier signal component of an OFDM signal, which is modulated into transmission information, to a plurality of LEDs of different colors. The information is added to a combination of a carrier frequency and an LED wavelength, when a carrier signal is allocated to an, in addition to each carrier signal being modulated into the information.

There is a need to prevent two receivers from converging on a state of receiving the same polarization state, fast start receivers, and ensure highly reliable operations. A polarization-multiplexed transmitter previously applies frequency shifts of frequencies +Δf and −Δf to X-polarization and Y-polarization digital information signals to be transmitted. Optical field modulators modulate and polarization-multiplex the signals. As a result, a frequency difference of 2Δf is supplied to X-polarization and Y-polarization components. A polarization diversity coherent optical receiver 215 receives the signal. A frequency estimation portion in a digital signal processing circuit detects a frequency difference signal in both polarization components. This signal is used to a polarization splitting circuit in the digital signal processing circuit.

An optical network includes a multidimensional coder and modulator for handling multiple-in-multiple-out MIMO spatial lightpath properties and content of any specific supercarrier, a spatial mode multiplexer responsive to orthogonal frequency division multiplexing OFDM transmissions and the multidimensional coder, a spatial-spectral routing node coupled over a fiber link to the spatial mode multiplexer for performing switching granularity by a spatial mode reconnection, a multidimensional decoder and demodulator; and a spatial mode demultiplexer coupled over a fiber link to the spatial-spectral routing node and responsive to the multidimensional decoder and demodulator.

An injection locked transmitter for an optical communication network includes a master seed laser source input substantially confined to a single longitudinal mode, an input data stream, and a laser injected modulator including at least one slave laser having a resonator frequency that is injection locked to a frequency of the single longitudinal mode of the master seed laser source. The laser injected modulator is configured to receive the master seed laser source input and the input data stream, and output a laser modulated data stream.

Various apparatus and methods for reducing inter-core crosstalk in a multicore optical fiber are disclosed. A multicore optical fiber may include a plurality of cores capable of transmitting optical signals, and a cladding surrounding the cores, the cladding having a heterogeneous refractive index such that the optical signals propagate at different velocities in different ones of the cores. A multicore optical fiber may include a first length including cores having heterogeneous modal velocities and a second length, adjacent to the first length, including cores having heterogeneous modal velocities, and the cores in the first length are aligned with cores in the second length having a different modal velocity. Inter-core cross talk in a multicore optical fiber may also be reduced by transmitting optical signals through cores of a multicore optical fiber and pumping light into the cores to create unequal modal velocities in the cores.

The biggest bottleneck in the Internet today is caused by the slow speed of routers, compared to the speeds that are achieved by optic fibers with DWDM (Dense Wave Division Multiplexing). Packet switching or something similar to it is needed not just for better utilization of the lines, but also because it is superior to circuit switching in many ways, such as better scalability as the Internet grows, better handling of traffic congestions, and better routing flexibility. But optical routers are currently unable to do packet switching except by translating the data to electronic data and then back, which is very inefficient. The present invention solves this problem by optically marking and detecting the packet headers or parts of them, translating at most only the headers or parts of them to electronics for making packet switching decisions, and keeping the rest of the packets in optical delay lines, and solving response-time problems in the router, so that the crude optical switches can execute the packet switching decisions at fast bit rates. This solution has very high scalability and becomes even more efficient when physical addresses are used. Another optimization described in this invention is improving routing efficiency and bandwidth utilization by grouping together identical data packets from the same source going to the same general area with a multiple list of targets connected to each copy of the data and sent together to the general target area. These grouped packets are then preferably broken down into smaller groups by the routers in the general target area and finally broken down to individual data packets for delivering to the final actual destinations. This optimization works best with Physical addresses, and can be very useful for example for optimizing the access to very popular sites such as for example Yahoo or CNN, and can be used also for example for more efficiently transferring streaming data, such as for example from Internet radio stations, or Internet TV stations which will probably exist in the next years. Another important optimization is a new architecture and principles for routing based on physical geographical IP addresses (such as for example based on GPS), in a way much more efficient than has been previously discussed in the literature that suggested using physical (geographical) addresses. This is preferably based on a hierarchy similar to a hierarchical road system, so that preferably the MAIN routers (and/or intermediary-level routers) are preferably also connected directly and preferably with high-bandwidth as peers between each other, without having to go through lower-level routers in order to reach their peers, so that once a higher-level router (and especially if it's one of the MAIN routers) decides to forward a packet (or a group of packets) to a higher-level peer, preferably the packets don't have to go through lower level routers. However, conversion from the current architecture to the new one can be done very easy, as shown in the description below.

An optical fiber communications system using spread spectrum code division multiple access techniques to achieve better bandwidth utilization. A transmitting user in the system encodes the optical signal using a first coding mask, and a receiving user decodes the received signal using two decoding masks, all of the masks having lengths N. The first mask is divided into two sections of lengths N/2 each, one of the sections defining a first sub-code of length N/2, while the other section blocks light. Each of the second and third masks is also divided into two sections, which correspond to the two sections of the first mask. The section of the second mask corresponding to the coded section of the first mask has a second code that is identical to the first code, and the section of the second mask corresponding to the blocked section of the first mask is also blocked. The section of the third mask corresponding to coded section of the first mask has a third code that is complementary to the first code, and the section of the third mask corresponding to the blocked section of the first mask is also blocked. Some users on the system have masks in which the first of the two sections are blocked and the second of the two sections are coded, while other users have masks in which the second of the two sections are blocked and the first of the two sections are coded. The first codes used to code the encoding masks are selected from a set of unipolar codes that are derived from a set of balanced bipolar orthogonal codes.

A space division multiplexed (SDM) transmission system that includes at least two segments of transmission media in which a spatial assignment of the two segments is different is provided. For example, the SDM transmission may include a first segment of transmission media having a first spatial assignment and a second segment of transmission media having a second spatial assignment, wherein the first spatial assignment differs from the second spatial assignment. An example method obtains an optical signal on a first segment of transmission media having a first spatial assignment and forwards the optical signal on a second segment of transmission media with a different spatial assignment. The transmission media may be a multi-core fiber (MCF), a multi-mode fiber (MMF), a few-mode fiber (FMF), or a ribbon cable comprising nominally uncoupled single-mode fiber (SMF).

A method is provided for detecting the skew between parallel light signals generated from a serial data stream. The method can be used with polarization multiplexed signal, as well as with wavelength division multiplexed signals, spatial division multiplexed signals, phase modulated signals, or intensity modulated signals. The method can be used with direct detection schemes as well as with coherent detection schemes. The method is provided with: imprinting dips between a fixed number of transmitted symbols of the parallel signals; detecting an electrical signal related to the dips for each parallel signal; and comparing the electrical signals in delay.

An example transmitter includes an encoder, a plurality of modulators and a spatial multiplexer. The encoder is configured to encode one or more input bit streams into a plurality of coded bit streams which are provided as output. Each modulator is configured to receive and modulate a respective one of the plurality of coded bit streams and to provide a modulated output signal. The spatial multiplexer is configured to spatially multiplex the plurality of modulated output signals for insertion on a spatially multiplexing waveguide. A modulated output signal(s) may be inserted onto a mode of a multi-mode fiber or onto a core of a multi-core fiber. In one embodiment, a subset of the plurality of spatially multiplexed modulated output signals which correspond to the one or more input bit streams must be simultaneously and spatially selectively detected in order to recover a first input bit stream.

A communication system has lighting equipment that has transmitter comprising multiple light-emitting elements that each emit light of different wavelengths and terminal equipment that has light-receiver comprising multiple light-receiving elements that receive optical signals for each of the different wavelengths.

A polarization multiplexing transmitter which generates polarization-multiplexed signals which are arbitrarily polarization-scrambled at high speed, without adding a polarization modulator and a polarization scrambler. In the transmitter, an orthogonally polarized signal generator includes two optical modulators which modulate the electric fields of optical signals and generate two optical signals with mutually orthogonal polarized waves. The transmitter includes electric field mappers which convert two data strings into electric field signals, polarization mappers which give different polarized waves to the two signals, polarization rotators which rotate the polarized waves of the signals uniformly, a polarization multiplexer which multiplexes the two polarization-rotated signals, a polarization demultiplexer which demultiplexes the multiplexed signal into polarized wave components of optical signals generated by the orthogonally polarized signal generator, and a driver. The optical modulators are driven to make the two demultiplexed electric field signals consistent with the electric fields of optical signals modulated by the modulators.