650 results about "Optical fiber communication systems" patented technology

This invention generally relates to an optical filter for a fiber optic communication system. A coupled multi-cavity optical filter may be used, following a directly modulated laser source, and converts a partially frequency modulated signal into a substantially amplitude modulated signal. The optical filter may compensate for the dispersion in the fiber optic transmission medium and may also lock the wavelength of the laser source.

A multimode optical fibre communications system, and in particular to a system in which non-linearities in the propagation of the signal through a multimode optical communications channel degrade the signal presented to the receiver. The system includes an optical transmitter unit for connection to a multimode optical fibre transmission link. The transmitter unit has a data input for receiving an input data signal, a data signal processing circuit and a source of optical radiation. The data signal processing circuit is arranged to receive the input data signal from the data input and to provide a processed data signal to the source of optical radiation and the source of optical radiation is arranged to generate from this an optical signal for transmission by a multimode optical fibre. The data processing circuit is arranged to provide from the input data signal a non-inverted data signal and an inverted data signal, receive a control signal for controlling the generation of the processed data signal, apply a controllable delay in accordance with the control signal to at least one of the non-inverted and inverted data signals, and combine the non-inverted and inverted signals after the application of the controllable delay(s) and gain factor(s) to generate the processed data signal.

Patch panel assemblies (150) that contain patch panel modules (50) for use in optical fiber telecommunication systems are disclosed. One of the patch panel assemblies includes a front mounting frame (210F) and at least one internal mounting frame (210I) that support a plurality of patch panel modules. The patch panel assembly also includes a hinge assembly (224) configured allow bend-insensitive fiber cables (70) to be routed therethrough. One of the patch panel assemblies includes a housing (152) with a drawer (270) that supports a plurality of patch panel modules. The patch panel modules employ bend-insensitive optical fibers (12C) to connect front and rear ports (92, 98) so that the patch panels have a reduced size as compared to conventional patch panel modules. The patch panel assemblies include a cable distribution box (300) that can store excess cable and that assists in routing bend-insensitive fiber optic cables within the patch panel assembly interior (200) in order to connect to select patch panel module jacks (90).

An improved fiber-optic communications system comprises a multi-mode waveguide carrying an optical signal, a single-mode waveguide optically coupled to and receiving the optical signal from the multi-mode waveguide and an adiabatic coupler optically coupled between the multi-mode waveguide and the single-mode waveguide. The multi-mode and single-mode waveguides may be optical fibers. The adiabatic coupler may comprise a tapered core surrounded by a cladding. Alternatively, the adiabatic coupler may comprise a core surrounded by a cladding, wherein the refractive index of at least one of the core and the cladding varies over the length of the adiabatic coupler.

An integrated maximum a posteriori equalization and turbo product coding (IMAP-TPC) system for optical fiber communications systems (OFCS) is provided that uses probabilistic characterization of the electrical current in the presence of inter-symbol interference (ISI) and noise to compensate their effects and improve the bit error rate. In the IMAP-TPC system, turbo product code (TPC) decoding is integrated with a symbol-by-symbol maximum a posteriori (MAP) detector. The MAP detector calculates the log-likelihood ratio of a received symbol using the conditional electrical probability density information, and hence obtains a much more accurate reliability measure than the traditional measure used in the TPC decoder.

In this invention, a radio frequency identification overlay network that automates the discovery and configuration management of all physical fiber optic connections within a distributed communications network is disclosed. Miniaturized, low crosstalk RFID tags at a first fiber optic receptacle location and miniature, distributed, multiplexed reader antenna at a distant, second fiber optic receptacle location are joined by a fiber optic link which transmits both optical data and RF electronic signals. This electronic-fiber optic interface is comprised of two separated, miniaturized resonant antenna in communication with another through a resonant RF transmission line integral to the fiber optic cable. This RFID overlay network is comprised of multiplexed RFID readers, RF resonant fiber optic cables, and miniaturized RFID tags attached to the connector receptacles of network elements. The RFID overlay network interrogates tags automatically and remotely through the RF transmissive and optically transmissive fiber optic patch cords, eliminating the need for manual readout by technicians.

A fiber optic communication system includes a device of switching and setting wavelength of optical signals used in communication by network-node equipments, which sets the mapping of the wavelength of the optical signal used in communication by the network node equipments, and the input / output ports of an array waveguide grating (AWG), so as to construct a predetermined logical network topology by a plurality of network node equipments which are connected via optical fibers to the array waveguide grating that outputs optical signals inputted to optical input ports, to predetermined optical output ports in accordance with the wavelength thereof. As well as enabling a simple construction, it is easy to realize flexible network design, construction, and operation, and different network groups can also be easily connected to each other. Moreover, a fiber optic communication system having robust security and which can be stably operated even at the time of failure is realized at low cost.

Data throughput rates are increased in an optical fiber communication system without requiring replacement of the existing optical fiber in a link. Channel throughput is increased by upgrading the components and circuitry in the head and terminal of an optical fiber communication system link. Aggregate throughput in a fiber optic link is increased beyond the range of conventional Wavelength Division Multiplexed (WDM) upgrades, while precluding the necessity of replacing existing fiber plants. The increase in system throughput is achieved by using advanced modulation techniques to encode greater amounts of data into the transmitted spectrum of a channel, thereby increasing the spectral efficiency of each channel. This novel method of increasing transmission capacity by upgrading the head and terminal of the system to achieve greater spectral efficiency and hence throughput, alleviates the need to replace existing fiber plants. Spectrally efficient complex modulation techniques can be supported by interface circuits with an increased level of signal processing capability in order to both encode multiple bits into a transmitted symbol and decode the original data from the received symbols.

A laser system using ultrashort laser pulses is provided. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and a spectrometer. Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and a SHG crystal. In yet another aspect of the present invention, a multiphoton intrapulse interference phase scan system and method characterize the spectral phase of femtosecond laser pulses. Fiber optic communication systems, photodynamic therapy and pulse characterization tests use the laser system with additional aspects of the present invention.

The present invention relates to an optical connector for use in a fibre optic communications system, and particularly an expanded beam optical connector (20) for connecting optical fibres. The connector (20) comprises a housing (6), a port (48) within the housing for receiving an end (35) of an optical fibre (38), a cylindrical ferrule (32) within the housing (6) having opposite first and second ends (33, 35), and an optical fibre stub held axially (14) within the ferrule (32) and extending between said ferrule ends (33, 35). The connector (20) also has a lens (8) for projecting and / or receiving an expanded beam (40) optically coupled with the optical fibre stub at the first ferrule end (33). A sleeve (34) surrounds the ferrule (32) and extends towards the port (48) axially away from the second ferrule end (35) to present an open end to the sleeve for receiving a termination ferrule (36) of an optical fibre (38) inserted into the port. The connector (20) has a connector portion (2, 4, 5) for connecting the optical fibre connector (20) to another expanded beam optical fibre connector so that said expanded beam (40) traverses between the connectors. A channel (28) extends through the housing (6) from the port (48) towards the lens (8), the ferrule (32) being secured by means of a cured adhesive (30) to the housing (6) and in alignment with respect to the lens (8), the open end of the sleeve (34) and / or the second end (35) of the ferrule being surrounded by a void (60) within the channel (28).

Data throughput rates are increased in an optical fiber communication system without requiring replacement of the existing optical fiber in a link. Channel throughput is increased by upgrading the components and circuitry in the head and terminal of an optical fiber communication system link. Aggregate throughput in a fiber optic link is increased beyond the range of conventional Wavelength Division Multiplexed (WDM) upgrades, while precluding the necessity of replacing existing fiber plants. The increase in system throughput is achieved by using advanced modulation techniques to encode greater amounts of data into the transmitted spectrum of a channel, thereby increasing the spectral efficiency of each channel. This novel method of increasing transmission capacity by upgrading the head and terminal of the system to achieve greater spectral efficiency and hence throughput, alleviates the need to replace existing fiber plants. Spectrally efficient complex modulation techniques can be supported by interface circuits with an increased level of signal processing capability in order to both encode multiple bits into a transmitted symbol and decode the original data from the received symbols.

A transponder assembly for use with fiber optic digital communication cables having multiple parallel optic fiber elements. The transponder assembly features separate transmitter and receiver ports and an electrical connector for connecting with computer or communication systems. The transponder assembly includes a parallel optic transmitter module and a parallel optic receiver module. The assembly also includes a circuit board on which a semiconductor chip useful for signal processing and the electrical connector are mounted. A Flex circuit is used in connecting the circuit board to the parallel optic modules. The semiconductor chip and electrical connector are mounted directly across from one another on opposite surfaces of the circuit board using ball grid arrays having overlapping attachment structures.

The invention relates to a low-attenuation single mode optical fiber used in an optical fiber communication system. The single mode optical fiber comprises a core layer and a wrapping layer. The single mode optical fiber is characterized in that the refractive index distribution n (r) of the core layer and the g-type refractive index distribution of the core layer meet the formula: n (r)=n0*[1-2*delta 1*(r / R1)*g]*1 / 2 (r<=R1), the delta 1 of the core layer ranges from -0.05% to +0.05%, g ranges from 10 to 30, and the radius R1 of the core layer ranges from 4.0 microns to 5.0 microns; the wrapping layer sequentially comprises an inner wrapping layer, a middle wrapping layer and an outer wrapping layer from inner to outer, the delta 2 of the inner wrapping layer ranges from -0.3% to -0.45%, the radius R2 ranges from 20 microns to 30 microns, and the delta 3 of the middle wrapping layer is larger than delta 2, the numerical relationship between the relative refraction difference and the radius of the middle wrapping layer and the relative refraction difference and the radius of the inner wrapping layer is V=(R3-R2)*(delta 3-delta 2), and V ranges from 0.5*10-2-micron% to 7*10-2-micron%. The attenuation coefficient, at the 1550-nanometer position, of the optical fiber is smaller than or equal to 0.180dB / km. The low-attenuation single mode optical fiber is low in optical fiber loss, good in manufacturing technology, low in cost and suitable for scale production.

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.

The invention relates to a low-attenuation bend-insensitive single-mode fiber, which is used in a fiber communication system and comprises a core layer and three claddings. The low-attenuation bend-insensitive single-mode fiber is characterized in that the relative refractive index difference delta1 of the core layer ranges from 0.1% to 0.30%, the radius R1 of the core layer ranges from 3.5 micrometers to 4.5 micrometers, the three claddings are arranged on the outside of the core layer, the first cladding is an inner cladding tightly encircling the core layer, the relative refractive index difference delta2 of the inner cladding ranges from -0.1% to 0.1%, the radius R2 of the inner cladding ranges from 8 micrometers to 10 micrometers, the second cladding is a depressed cladding tightly encircling the inner cladding, the relative refractive index difference delta3 of the depressed cladding ranges from -0.4% to -0.1%, the delta3 is smaller than the delta2, the radius R3 of the depressed cladding ranges from 12 micrometers to 20 micrometers, the third cladding is an outer cladding tightly encircling all sub-claddings of the depressed cladding, and the relative refractive index difference delta4 of the outer cladding ranges from -0.2% to 0.1%. On the basis of comprehensive compatibility to existing G.652 standards, the low-attenuation bend-insensitive single-mode fiber has an attenuation performance far superior to that of a conventional G.652.D fiber, the microscopic bending requirement of G.657.A1 standards can be met, and application of a dense wavelength division multiplexing system is facilitated.

The invention discloses a self-correlation optical fiber communication system based on mode division multiplexing. The self-correlation optical fiber communication system based on mode division multiplexing comprises an optical carrier input unit, optical signal modulation units, a wavelength division multiplexing unit, a mode division multiplexing and demultiplexing unit, a wavelength division multiplexing unit and coherent reception units. The mode division multiplexing and reconciliation multiplexing unit comprises a mode multiplexer and mode demultiplexer, and the mode multiplexer and the mode demultiplexer are connected through few-mode optical fibers. The optical carrier input unit is connected with each optical signal modulation unit, the wavelength division multiplexing unit and the mode multiplexer through single-mode optical fibers. The mode multiplexer is connected with the mode demultiplexer through few-mode optical fibers. The mode demultiplexer is connected with the wavelength division multiplexing unit and each coherent reception unit through single-mode optical fibers. The optical carrier input unit is further connected with the wavelength division multiplexing unit. The self-correlation optical fiber communication system based on mode division multiplexing eliminates an expensive narrow line width adjustable local oscillator light source which is arranged at a reception end, enables a laser to be conveniently managed and maintained, is free from using frequency offset estimation in a digital signal processor (DSP) and phase retrieval algorithm, reduces complexity of the DSP and has the advantages of being high in spectrum effectiveness and big in nonlinearity tolerance.

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.

Optical signals are received from a free-space link by directing received light onto a plurality of microlenses and then directing light received through each of the microlenses into a respective single mode optical fiber (SMF). Light beams from the SMFs are combined into a single light beam in one SMF. The single light beam is amplified with a multi-wavelength fiber amplifier and attenuated with a variable optical attenuator. The power gain of the multi-wavelength fiber amplifier and the attenuation of the variable optical attenuator are controlled. The single light beam is directed into a fiber optic communication system that is optically coupled to the variable optical attenuator.

An object of disclosed technology is to control lasing wavelengths so that a wavelength shift does not occurs. Another object is to permit wavelengths of a light source for wavelength division multiplexing optical-fiber communication system to be variable in response to an ITU-TS grid. A means for achieving the objects is as follows: locating an etalon in a light path of diode laser light, which is a parallel plane wave changed by a collimator lens; generating a wavelength error signal from a difference between both of divided pieces of light from transmitted light or reflected light; and locking a wavelength of a diode laser device according to the wavelength error signal.

A heater system for heating an erbium-doped fiber amplifier (EDFA) of a fiber optic communication system operable in an environment. The heater system includes a pump laser for providing optical power to an erbium fiber in the EDFA. The pump laser is cooled by a thermoelectric cooler (TEC) when a predetermined maximum temperature is reached to maintain the temperature of the laser below the maximum temperature value. The temperature of the laser is sensed by a temperature sensor and is conveyed to a control circuit for generating a control signal. A heater unit is thermally connected to the erbium fiber and is controlled by the control signal in the event that the sensed temperature falls below a predetermined minimum value to maintain the temperature of the fiber above the minimum temperature value. A switch is connected between the control circuit, the TEC and the heater to automatically direct current to either the heater or the TEC depending on the sensed temperature.

Various circuit techniques for implementing ultra high speed circuits use current-controlled CMOS (C3MOS) logic fabricated in conventional CMOS process technology. An entire family of logic elements including inverter / buffers, level shifters, NAND, NOR, XOR gates, latches, flip-flops and the like are implemented using C3MOS techniques. Optimum balance between power consumption and speed for each circuit application is achieve by combining high speed C3MOS logic with low power conventional CMOS logic. The combined C3MOS / CMOS logic allows greater integration of circuits such as high speed transceivers used in fiber optic communication systems. The C3MOS structure enables the use of a power supply voltage that may be larger than the voltage required by the CMOS fabrication process, further enhancing the performance of the circuit.

A high speed optical communication system (>=10 Gbit / s) is compensated for temperature variation by providing it with one or more automatic dispersion compensation modules. Each module has an adjustable dispersion element, a data integrity monitor and a feedback network whereby the monitor adjusts the dispersion element to compensate for temperature variation. In a preferred embodiment the dispersion compensating modules comprise chirped fiber Bragg gratings in which the chirp is induced in the grating by passing a current along distributed thin film heaters deposited along the length of the fiber. The magnitude of the applied current determines the dispersion of the grating. A data integrity monitor is configured to sense the integrity of transmitted data and to provide electrical feedback for controlling the current applied to the grating.