Abstract: A wavelength division multiplexing (WDM) transmission system for transmitting a wavelength division multiplexed signal light from a sender transmission apparatus to a receiver transmission apparatus is provided. The system comprises a computing unit that subtracts from a first optical signal noise ratio (OSNR) of the signal light measured by the receiver transmission apparatus a second OSNR ascribed to a sideband of the signal light measured by the sender transmission apparatus so as to compute a corrected OSNR of an amplified spontaneous emission (ASE) noise light with a reduction of an effect of the sideband.

Abstract: A pumping unit supplies pumping light to a fiber connecting medium; a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value.

Abstract: A pumping unit supplies pumping light to a fiber connecting medium; a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value.

Abstract: A pumping unit supplies pumping light to a fiber connecting medium; a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value.

Abstract: A pumping unit supplies pumping light to a fiber connecting medium; a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value.

Abstract: A pumping unit supplies pumping light to a fiber connecting medium; a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value.

Abstract: A pumping unit supplies pumping light to a fiber connecting medium; a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value.

Abstract: A wavelength division multiplexing (WDM) transmission system for transmitting a wavelength division multiplexed signal light from a sender transmission apparatus to a receiver transmission apparatus is provided. The system comprises a computing unit that subtracts from a first optical signal noise ratio (OSNR) of the signal light measured by the receiver transmission apparatus a second OSNR ascribed to a sideband of the signal light measured by the sender transmission apparatus so as to compute a corrected OSNR of an amplified spontaneous emission (ASE) noise light with a reduction of an effect of the sideband.

Abstract: A pumping unit supplies pumping light to a fiber connecting medium; a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value.

Abstract: A pumping unit supplies pumping light to a fiber connecting medium, a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value.

Abstract: An optical amplifier includes an output unit that outputs a loss monitoring light having a wavelength that causes neither absorption nor gain with respect to each of the wavelengths of a light signal to be amplified with EDFs; a multiplexing unit that multiplexes the loss monitoring light with the light signal at an input stage of the light signal; a demultiplexing unit that demultiplexes the loss monitoring light from multiplexed light signal at an output stage of the light signal; a detecting unit that detects intensity of loss monitoring light at the input stage and intensity of loss monitoring light at the output stage; a calculating unit that calculates, based on the intensities, a loss of the loss monitoring light that has occurred between the input stage and the output stage; and a control unit that controls, based on the loss, the variable optical attenuator.

Abstract: An optical transmission device in which optical signal switching is performed to allow the device to be reduced in size and also which is capable of efficient recovery from fault, thereby improving system expansibility and communication quality. Overhead terminating section converts an optical signal to an electric signal and performs an overhead process including extraction of fault information and setting of status information. Optical switch section performs a process of switching the optical signal between active and standby lines, and switching control section provides a switching command to the optical switch section in accordance with the fault information.

Abstract: A pumping unit supplies pumping light to a fiber connecting medium; a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value.

Abstract: An optical transmission unit and optical transmission system which have more efficient failure recovery functions to provide improved communication services, without increasing the size of network equipment. A control channel manager manages a control channel, as well as a control channel signal on that channel, for the purpose of failure recovery of optical signal transport. An optical switch fabric switches optical signal paths to perform protection switching between working facilities and protection facilities. A protection switching controller sends a switching command to the optical switch fabric, based on the information provided through the control channel.

Abstract: An optical transmission device in which optical signal switching is performed to allow the device to be reduced in size and also which is capable of efficient recovery from fault, thereby improving system expansibility and communication quality. Overhead terminating section converts an optical signal to an electric signal and performs an overhead process including extraction of fault information and setting of status information. Optical switch section performs a process of switching the optical signal between active and standby lines, and switching control section provides a switching command to the optical switch section in accordance with the fault information.

Abstract: Disclosed is an optical heterodyne frequency modulator for outputting an FM signal by driving a frequency modulating laser diode with an input signal to generate an FM optical signal, combining waves of a local optical signal with waves of the FM optical signal, and subjecting the combined signal to optical heterodyne detection to output the FM signal which is frequency-modulated by the input signal. A signal having a phase opposite that of a signal input to a frequency modulating laser diode is generated, the amplitude of the FM optical signal, which is output by the frequency modulating laser diode, is controlled in such a manner that the optical power is rendered constant, the amplitude-modulated FM optical signal and the local optical signal are combined, and the combined signal is then subjected to optical heterodyne detection, whereby an FM signal is produced as an output.

Abstract: An apparatus and method for providing distortion to an input signal. A first alternating current component is separated from the input signal, to provide a first signal representing the first alternating current component and a second signal representing the input signal having the first alternating current component separated therefrom. The signal level of the first and second signals is adjusted. Nonlinear distortion is provided to the signal level adjusted first signal, to produce a distorted first signal. The signal level adjusted second signal is combined with the distorted first signal, to produce a corresponding output signal.

Abstract: A video-on-demand system is comprised of a source station which transmits video signals of different channels on an optical transmission line to a number of subscriber terminals in accordance with subscriber requests. The source station includes a multiplexing unit which generates a frequency division multiplexed signal from the video signals in such a manner that vertical synchronizations of the video signals of different channels are in accordance with each other, and transmits the multiplexed signal to each subscriber terminal. Each subscriber terminal includes a transmitting unit which transmits a control signal indicative of a subscriber request to the source station at a frequency band different from frequency bands of the video signals of the frequency division multiplexed signal, the control signal being transmitted during a vertical blanking period of the video signals.

Abstract: A multi-media mailing method and system including a plurality of mailing centers in a network for handling facsimile, audio and text signals, wherein different mailing centers function independently of each other but hold information commonly while a utilizer can get similar mailing service from whichever center it accesses. When a temporary utilizer subscriber whose subscriber information is registered in a first mailing center accesses a second mailing center in which the subscriber information is not registered, the second mailing center transmits to any other mailing center, an inquiry whether or not the subscriber information of the temporary utilizer subscriber is registered. If the subscriber information is received from first mailing center in which the subscriber information of the temporary utilizer subscriber information is stored, the second mailing center temporarily stores the subscriber information to permit the access by the temporary utilizer subscriber by way of the second mailing center.