1468results about "Electromagnetic repeaters" patented technology

The invention relates to a method of activating an optical communication system comprising a plurality of optical amplifiers having an optical amplifier, between optical transmission lines in which wavelength-division multiplex optical signals are transmitted. The method comprises steps of: generating a desired slope in a desired wavelength range of a gain wavelength curve of the optical amplifier; adjusting an output of the optical amplifier to a desired output level; performing the above two steps in a plurality of optical repeater stations, the steps being carried out in sequence from the first to the last optical repeater stations; and adjusting a level in each optical signal in the wavelength-division multiplex optical signal so as to have substantially constant optical signal-to-noise ratios in the optical signals to be received. Activating the optical communication system according to this procedure allows proper execution of gain slope compensation, output control, and pre-emphasis control.

An optical communications network includes a terminal which can simultaneously receive and modulate an optical signal. The terminal includes an optical modulator which is controlled by varying the bias voltage applied to it.

A loss-less, optical add/drop multiplexer according to the present invention includes a rare earth-doped fiber amplifier integrated with a wavelength-selective fiber path coupled between two directional optical transfer devices for selectively adding and dropping optical signals from a multi-wavelength signal, such as a wavelength division multiplexed optical signal. One or more fiber gratings are disposed along the length of the rare earth-doped fiber amplifier or between segments of the rare earth-doped fiber so that at least one grating is used for reflecting each optical signal that is expected to be added to or dropped from the multi-wavelength optical signal. By using this configuration, appropriate amplification is provided to compensate for losses in the add, drop, and through paths.

A signal transmitting apparatus for an optical base station is disclosed. According to the invention, a base station outputs a digital IQ signal to an optical connecting unit. The optical connecting unit processes the digital IQ signal digitally, and transmits the digital signal over an optical network to a remotely located optical base station. The remote station digitally processes the signal before converting to an RF signal for transmission. The invention advantageously decreases signal loss and noise associated with analog processing in the optical connecting units and remote stations in the related art. System reliability is also improved.

A radio-over-fiber (RoF) system and method for controlling a transmission time is provided. In a Time Division Duplex (TDD) wireless communication system comprising a Base Station (BS) having a donor and a remote connected thereto via am optical fiber, upstream and downstream Radio Frequency (RF) signals are transmitted and received, and by reliably transmitting a switch control signal to the remote and simultaneously compensating for a transmission time delay occurring in the optical cable, time synchronization of the upstream and downstream RF signals transmitted and received via antennas of the BS and the remote is controlled, thereby efficiently increasing the performance of a TDD wireless service system.

A radio over fiber link apparatus for transmitting/receiving radio frequency up/downlink signals in a TDD mobile communication system. The radio over fiber link apparatus includes a center site for receiving radio frequency signals from an access point of the mobile communication system. The center site has a first electro-optic converter for converting the radio frequency signals into optical signals, bias control of the first electro-optic converter being performed based on the switching of TDD signals; and a remote for transmitting the radio frequency signals to a mobile communication terminal through an antenna. The remote site has a first photoelectric converter for converting the optical signals transmitted through an optical fiber from the center site into radio frequency signals.

An optical network for bi-directional communication includes: a base station for generating downlink optical signals and detecting uplink optical signals; and a remote antenna unit for transmitting the downlink optical signals and generating the uplink optical signals to the base station; wherein the remote antenna includes: an optical detector for converting the downlink optical signals into downlink radio signals; an antenna for transmitting the downlink radio signals to outside thereof, and receiving the uplink radio signals in wireless communication; a semiconductor optical amplifier for converting the uplink radio signals into the uplink optical signals to output the uplink optical signals to the base station; and a circulating device having a plurality of ports, each of which is connected to the antenna, the optical detector, and the semiconductor optical amplifier, respectively.

An erbium fiber (or erbium-ytterbium) based chirped pulse amplification system is illustrated. The use of fiber amplifiers operating in the telecommunications window enables the implementation of telecommunications components and telecommunications compatible assembly procedures with superior mechanical stability.

A repeater station 10 detects whether or not an abnormality exists in each of signal light and monitor light having arrived from a terminal station 1 or a repeater station 20, and controls, according to the result of detection, operations of optical amplifiers 11 and 12 and the monitor light. In the case where both of the signal light and monitor light arriving from the terminal station 1 via the optical transmission line for the downstream direction are abnormal, the optical amplifier 11 for the downstream direction stops its amplifying operation by itself, whereas a monitor control apparatus 13 stops the amplifying operation of the other optical amplifier for the upstream direction and also stops transmitting the monitor light to the terminal station 1 in the upstream direction.

In an optical LAN system, an optical connector is provided between the input and output optical fiber cables and each of the node devices. The optical connector includes a movable body (a switch body) having a prism. The movable body is switched selectively between a first position (a first state) at which the input and output optical fiber cables are optically connected to the node device and a second position (a second state) in which the input optical fiber cable and the output optical fiber cable are optically connected to each other in such a manner as to bypass the node device. This arrangement suppresses a network crash by means of a relatively simple configuration.

Tunable add/drop optical device for injecting or extracting (add/drop) at least a selected optical channel or carrier wavelength in or from a set of multiplexed channels or carriers of different wavelengths comprising a plurality of directional couplers (AD1 . . . AD6) and a plurality of phase-shift stages (SF1 . . . SF5) alternately connected in cascade, wherein each phase-shift stage defines a certain optical path length difference (DELTAL1 . . . DELTAL5) between two distinct optical paths of the stage. The tuning is performed modifying the refraction index of one path of said phase shift stages by means of Joule effect heating strips (L1 . . . L5) or by means of metallic field plates adapted to receive a signal suitable to modify the electric field intensity. The first two phase-shift stages of said plurality of phase-shift stages have differences of length of optical paths different from each other and in a preestablished ratio while the remaining phase-shift stages have differences of length of optical paths identical. It is thus possible to provide a device having an exceptionally flat cross response characteristic, substantially free of ripple due to an inevitable truncation of the Fourier expansion series.

A core unit arranged in a transmission path includes a through path for causing an input signal to an input port to pass through to an output port, a drop-side port 25a that drops the input signal having a predetermined wavelength, and an add-side port 25b that adds channel having a predetermined wavelength to the input light.

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.

An interference resistant infrared receiver and extension system is disclosed. A receiver in accordance with the present invention comprises at least one infrared photodetector configured to detect impinging infrared light of a desired wavelength, an amplifier, coupled to the at least one infrared photodetector, for amplifying an electrical signal generated by the at least one infrared photodetector, and a bandpass filter, coupled to the at least one infrared photodetector, wherein the desired impinging infrared light passes through the bandpass filter before impinging on the at least one infrared photodetector, wherein the bandpass filter is configured to pass desired impinging infrared light and block undesired impinging wavelengths of light.

The present invention relates to an optical cross connect unit comprising M wavelength separating sections for receiving multiplexed optical signals each having N kinds of wavelengths different from each other through M optical fibers, respectively, and for wavelength-separating each of the multiplexed optical signals into N optical signals, M optical reproduction relay sections each for conducting an optical reproduction and relay in a manner of making a conversion of each of the N optical signals, wavelength-separated in each of the wavelength separating sections, into an electric signal and then modulating it with a desired optical wavelength, a refill section for mutually refilling M sets of optical signals optically reproduced and relayed in the optical reproduction relay sections, a focusing section for focusing the M sets of optical signals refilled in the refill section, and a light source unit for supplying input lights having desired wavelengths to be modulated in the M optical reproduction relay sections. The light source unit includes N light sources for outputting lights having the N kinds of optical wavelengths, a multiplexing and branching section for multiplexing the lights from the N light sources to produce a multiplexed light having N kinds of optical wavelength components and further for branching the multiplexed light into MxN lights to output them as multiplexed and distributed lights, M wavelength filter sections for distributively receiving N multiplexed and distributed lights of the MxN multiplexed and distributed lights branched in the multiplexing and branching section to output N lights due to the passage of only arbitrary wavelengths of the N kinds of optical wavelengths, and a wavelength setting control section for setting optical wavelengths, which pass through the wavelength filter sections, so that they differ from each other. The N lights from each of the M wavelength filter sections are supplied as the input lights. In the case that many light sources are necessary for the modulation processing by modulators or the like, this optical cross connect unit is also suitable because of using given wavelengths from a small number of light sources for a lot of modulation processing.

Systems and methods for reconditioning an optical signal by OE (optical-to-electrical) converting the signal, recovering clock and data information and performing 3R reconditioning to reamplify, retime and reshape the converted electrical signal, and EO converting the signal back to the optical domain while the FEC and/or Framing encoding of the optical signal remains intact. An exemplary apparatus may be configured to include a receiver 302 with an optical-to-electrical converter, an electronic distortion estimation and compensation unit 304, an electrical-to-optical converter 308, and a transmitter 310.

A WDM optical transmission system of the invention has a configuration where WDM light generated at a wavelength multiplexing station is transmitted via a plurality of stations such as optical add-drop stations, arranged on an optical transmission line, and control of the power of the optical signals of respective wavelengths included in the WDM light is performed in the wavelength multiplexing station and the optical add-drop stations. A device is provided which communicates between stations, optical signals including information related to the control state of the optical signal power in each station, so that after control of the optical signal power at an upstream station is complete, control of the optical signal power at the downstream station is executed. As a result, stable control in respective stations can be performed even at the time of increasing or decreasing the number of wavelengths.

The present invention relates to an optical transmission apparatus capable of suppressing a transitional gain variation when a number of signal wavelengths changes, and maintaining communication quality in optical signals. The optical transmission apparatus is provided with an optical power control device that varies light power of light for each wavelength component corresponding to a wavelength channel, the light including signal light and spontaneous emission light; a wavelength arrangement information obtaining unit that obtains arrangement information of the wavelength channel of the signal light; and a control unit that controls the power control device based on the arrangement information obtained at the wavelength arrangement information obtaining unit so that light power of a wavelength component of the signal light and light power of a wavelength component other than the wavelength component of the signal light become substantially equal.