Abstract: Power of multi-path interference light is measured by setting the cycle of pulse modulation for a light source in correspondence with the length of an optical medium of a target to be measured, by inputting pulse light after being modulated to the target to be measured, by modulating the pulse signal light output from the target to be measured with the use of a pulse signal for modulation having the same cycle as the set cycle, and by observing the wavelength dependency of the power of the light after being modulated. In this way, a modulation condition is set according to a condition of a target to be measured when multi-path interference light caused by double Rayleigh scattering light or reflection at the end of a connector is measured with a pulse-OSA method, so that measurement accuracy is improved.

Abstract: An amplification medium simulation apparatus comprises a basic data retaining unit 21, an input signal beam information retaining unit 22, and a simulation executing unit 31 approximating and calculating an output signal beam power at each signal beam wavelength outputted from the amplification medium involving a fluctuation in ion population at the metastable energy level in the amplification medium due to input of the input signal beam, by using contents retained in the basic data retaining unit 21 and the input signal beam information retaining unit 22, and outputting a result of calculation as a result of simulation of performance of the amplification medium.

Abstract: Multi-wavelength light is inputted to an erbium-doped fiber as an optical amplification medium. Pump light is supplied to this erbium-doped fiber. When a transition from a state signal light on the short wavelength area in the multi-wavelength is input in the erbium-doped fiber to a state the signal light is not input, the output power of signal light on the long wavelength area in the multi-wavelength light can vary. The wavelength of pump light is selected in such a way that the output power of the signal light on the long wavelength area can not be negative when the power varies.

Abstract: In one of control methods of a bidirectional pumping type Raman amplifier according to the present invention, the power of a pumping light supplied to a rare-earth element doped optical fiber is increased or decreased, and a transmission wavelength characteristic of a dynamic gain equalizer is controlled according to a change in a gain wavelength characteristic occurring due to the increase or decrease of the power of the pumping light, to thereby extend a signal light band to either a short wavelength side or a long wavelength side. As a result, it becomes possible to realize a signal light band extension service at a low cost.

Abstract: An optical amplifier, or optical repeater, for amplifying wavelength division multiplexed (WDM) light. A first demultiplexer demultiplexes the WDM light into first and second lights corresponding to different wavelengths in the WDM light. First and second optical amplifiers amplify the first and second lights, respectively. A first multiplexer multiplexes the amplified first and second lights into a multiplexed light. A dispersion compensator compensates for dispersion in the multiplexed light. A second demultiplexer demultiplexes the dispersion compensated, multiplexed light into the first and second lights. Third and fourth optical amplifiers amplify the demultiplexed first and second lights, respectively. A second multiplexer multiplexes the amplified first and second lights from the third and fourth optical amplifiers into a WDM light. The optical amplifier can be configured so that the first and second lights travel through the dispersion compensator in opposite directions.

Abstract: An optical amplifier for amplifying WDM light which includes an optical fiber used as an optical amplification medium for amplifying WDM light. A pump light source is provided to generate pump light and an optical splitter is provided to generate first branch pump light and second branch pump light from the pump light. The optical amplifier further includes an optical device guiding the first branch pump light to the optical fiber and guiding the second branch pump light to a transmission line connected to an input side of the optical amplifier.

Abstract: An optical amplifying apparatus is composed of a light amplifying part for amplifying light and an input light controlling part for inputting, to the light amplifying part, probe light that serves to adjust the optical power of input light of the optical amplifying part. Receiving light having constant optical power, the optical amplifying part operates stably. In particular, the optical amplifying part stably operates even in a case where input light is a WDM optical signal and the number of multiplexed optical signals increases or decreases. The OADM of the present invention comprises such an optical amplifying apparatus.

Abstract: The present invention has an object to provide a Raman amplifier, a WDM optical communication system and a method of controlling the Raman amplification, capable of optimizing amplification characteristics in response to a change of operating conditions of the system so that transmission quality of the WDM signal light can be maintained in good.

Abstract: An optical amplifier, or optical repeater, for amplifying wavelength division multiplexed (WDM) light. A first demultiplexer demultiplexes the WDM light into first and second lights corresponding to different wavelengths in the WDM light. First and second optical amplifiers amplify the first and second lights, respectively. A first multiplexer multiplexes the amplified first and second lights into a multiplexed light. A dispersion compensator compensates for dispersion in the multiplexed light. A second demultiplexer demultiplexes the dispersion compensated, multiplexed light into the first and second lights. Third and fourth optical amplifiers amplify the demultiplexed first and second lights, respectively. A second multiplexer multiplexes the amplified first and second lights from the third and fourth optical amplifiers into a WDM light. The optical amplifier can be configured so that the first and second lights travel through the dispersion compensator in opposite directions.

Abstract: A Raman amplifier for amplifying a wavelength division multiplexed (WDM) light including signal lights wavelength division multiplexed together. The amplifier includes an optical amplifying medium and a controller. The optical amplifying medium uses Raman amplification to amplify the WDM light in accordance with multiplexed pump lights of different wavelengths traveling through the optical amplifying medium. The WDM light is amplified in a wavelength band divided into a plurality of individual wavelength bands. The controller controls power of each pump light based on a wavelength characteristic of gain generated in the optical amplifying medium in the individual wavelength bands.

Abstract: A rare earth element doped fiber forming an optical amplifier is pumped with a plurality of pumping lights to prevent drop of the inversion population ratio in the length direction of the rare earth element doped fiber.

Abstract: The present invention aims at providing an optical amplification apparatus for improving noise characteristics by controlling an amplification operation by assuming a noise figure of the overall apparatus and by taking influences of noise light due to Raman amplification into consideration, and a controlling method of the optical amplification apparatus.

Abstract: Disclosed is an apparatus for controlling wavelength-division-multiplexed light wherein overall power of wavelength-division-multiplexed light is rendered constant through control for uniformalizing the level of only one wave of maximum power, and wherein the levels of respective channels are made substantially uniform. Optical level control means controls the optical level of propagating wavelength-division-multiplexed light, and a portion of the wavelength-division-multiplexed light output from the output level control means is branched to a tunable optical filter, which selectively outputs the light of each wavelength contained in the wavelength-division-multiplexed light. The light of each wavelength output from the optical filter is photoelectrically converted to an electric signal by photoelectric conversion means.

Abstract: An optical amplifying apparatus which includes an optical amplifier, an optical attenuator and a controller. The optical amplifier amplifies a light signal having a variable number of channels. The optical attenuator passes the amplified light signal and has a variable light transmissivity. Prior to varying the number of channels in the light signal, the controller varies the light transmissivity of the optical attenuator so that a power level of the amplified light signal is maintained at an approximately constant level that depends on the number of channels in the light signal prior to the varying the number of channels. While the number of channels in the light signal is being varied, the controller maintains the light transmissivity of the optical attenuator to be constant.

Abstract: An optical amplifying apparatus which includes an optical amplifier, an optical attenuator and a controller. The optical amplifier amplifies a light signal having a variable number of channels. The optical attenuator passes the amplified light signal and has a variable light transmissivity. Prior to varying the number of channels in the light signal, the controller varies the light transmissivity of the optical attenuator so that a power level of the amplified light signal is maintained at an approximately constant level that depends on the number of channels in the light signal prior to the varying the number of channels. While the number of channels in the light signal is being varied, the controller maintains the light transmissivity of the optical attenuator to be constant.

Abstract: The present invention has an object to provide a Raman amplifier, a WDM optical communication system and a method of controlling the Raman amplification, capable of optimizing amplification characteristics in response to a change of operating conditions of the system so that transmission quality of the WDM signal light can be maintained in good.

Abstract: A Raman amplifier for amplifying a wavelength division multiplexed (WDM) light including signal lights wavelength division multiplexed together. The amplifier includes an optical amplifying medium and a controller. The optical amplifying medium uses Raman amplification to amplify the WDM light in accordance with multiplexed pump lights of different wavelengths traveling through the optical amplifying medium. The WDM light is amplified in a wavelength band divided into a plurality of individual wavelength bands. The controller controls power of each pump light based on a wavelength characteristic of gain generated in the optical amplifying medium in the individual wavelength bands.

Abstract: An object of the invention is to provide an optical amplification apparatus using Raman amplification, which can reliably judge an input interruption of signal light and can shut down the supply of excitation light in accordance with a judged input interruption of the signal light. To this end, the optical amplification apparatus of the present invention comprises an input interruption detection means for detecting a noise light component due to the Raman amplification, and judging an input interruption of the signal light based on the detection result, and further comprises a shut down control means for shutting down supply of the excitation light when an input interruption of the signal light is judged by the input interruption detection means.

Abstract: An object of the present invention is to provide at low cost, a highly functional and small size optical amplifier, which realizes a polarization mode dispersion (PMD) compensation function and an optical amplifying function, with a simple construction.

Abstract: The present invention relates to a device for optical amplification, and a primary object of the present invention is to provide a method and device for optical amplification which can maintain the wavelength characteristic of gain constant and can obtain a wide input dynamic range. The device according to the present invention includes a first optical amplifying unit having a Raman amplifying medium and a first pump source for pumping the Raman amplifying medium, and a second optical amplifying unit optically connected to a rear stage of the first optical amplifying unit. The second optical amplifying unit has an optical amplifying medium and second pump sources for pumping the optical amplifying medium. The present invention is characterized by a control unit for controlling the gain of the first optical amplifying unit so that variations in output power of the first optical amplifying unit due to variations in input power of the first optical amplifying unit are canceled.