Abstract: A dispersion compensating apparatus includes a tunable dispersion compensator that dispersion-compensates an optical signal using a group delay property that is asymmetrical in bands outside an effective band; a set device that sets a dispersion compensation amount in the tunable dispersion compensator; and a shifter that shifts a central frequency of the effective band of the tunable dispersion compensator, based on the dispersion compensation amount set by the set device.

Abstract: An optical amplification device which includes first and second optical amplifiers, and a controller. The first optical amplifier receives a light and amplifies the received light. The second optical amplifier receives the light amplified by the first optical amplifier, and amplifies the received light. When a level of the light received by the first optical amplifier changes by ?, the controller controls a level of the light received by the second optical amplifier to change by approximately ??. In various embodiments, the controller causes the sum of the gains of the first and second optical amplifiers to be constant. In other embodiments, the optical amplification device includes first and second optical amplifier and a gain adjustor. The gain adjustor detects a deviation in gain of the first optical amplifier from a target gain, and adjusts the gain of the second optical amplifier to compensate for the detected deviation.

Abstract: In an optical amplifier, an input light is supplied to one end of an optical fiber connected to an output port, and the power of a light in an opposite direction which is input to the output port from the one end of the optical fiber, is measured, thereby obtaining a stimulated Brillouin scattering (SBS) occurrence threshold in the optical fiber based on the measurement result. Then, using the SBS occurrence threshold, a relation between the input light power and an occurrence amount of the self phase modulation (SPM) or the like in the optical fiber is obtained to be reflected on a control of the optical amplifier, so that an occurrence of the SPM or the like in the optical fiber is suppressed. As a result, it becomes possible to accurately measure, with a simple configuration, the nonlinear optical properties of the optical fiber actually connected to the output port of the optical amplifier, so that the optical S/N ratio degradation due to a nonlinear optical effect can be effectively suppressed.

Abstract: In an optical amplifier of the present invention, an input light is supplied to one end of an optical fiber connected to an output port, and the power of a light in an opposite direction which is input to the output port from the one end of the optical fiber, is measured, thereby obtaining a stimulated Brillouin scattering (SBS) occurrence threshold in the optical fiber based on the measurement result. Then, using the SBS occurrence threshold, a relation been the input light power and an occurrence amount of the self phase modulation (SPM) or the like in the optical fiber is obtained to be reflected on a control of the optical amplifier, so that an occurrence of the SPM or the like in the optical fiber is suppressed.

Abstract: An optical amplifier includes a light source that outputs light having an intensity corresponding to a supplied driving power; a modulator that modulates the light output from the light source in response to an input modulation signal; a Raman amplifier that performs Raman amplification on the light modulated by the modulator using a highly-nonlinear medium; and a driver that supplies the driving power to drive the light source and inputs the modulation signal to the modulator. The driver starts inputting the modulation signal to the modulation unit before the intensity of the light propagating through the Raman amplifier exceeds an intensity value at which stimulated Brillouin scattering occurs in the Raman amplifier.

Abstract: An optical fiber reel storing a plurality of optical fibers having an annular frame; a first reel portion provided around an radially outer peripheral surface of the annular frame and receiving at least one of the plurality of optical fibers wound up around the radially outer peripheral surface; and, a second reel portion provided radially inside the annular frame and housing at least one of the plurality of optical fiber therein.

Abstract: According to an aspect of the embodiment of the invention, an optical amplifier including an input port, an output port, a plurality of amplifying parts, an optical attenuator, a gain controller and an optical attenuator controller. The plurality of amplifying parts includes an optical amplification medium and a pumping light source for generating pump light. The optical attenuator is optically connected between the amplifying parts. The gain controller controls the pump light power of the pump sources, respectively, in such a way that the ratio decreases in accordance with the gain set value increasing and the ratio interpose between a first threshold level and a second threshold level. The optical attenuator controller controls attenuation of the optical attenuator in order to maintain the sum of generating gains of the amplifying parts in the gain set value in accordance with a state of the signal light inputted into the input port.

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: An amount of ASE generated changes due to a temperature and respective powers of signals input to and output from an optical amplifying unit, causing a fluctuation of a gain of the optical amplifying unit. A photodiode on an input side and a photodiode on an output side detect the input and output powers, and temperature detecting unit detects an operating temperature of the optical amplifier. A control unit corrects the amount of ASE generated, based on at least one of the detected input and output signal powers and on the detected temperature according to AGC control, which controls driving of an excitation LD for the optical amplifier to keep a gain of the optical amplifier constant.

Abstract: In an optical amplifier of the present invention, an input light is supplied to one end of an optical fiber connected to an output port, and the power of a light In an opposite direction which is input to the output port from the one end of the optical fiber, is measured, thereby obtaining a stimulated Brillouin scattering (SBS) occurrence threshold in the optical fiber based on the measurement result. Then, using the SBS occurrence threshold, a relation been the input light power and an occurrence amount of the self phase modulation (SPM) or the like in the optical fiber is obtained to be reflected on a control of the optical amplifier, so that an occurrence of the SPM or the like in the optical fiber is suppressed.

Abstract: An optical apparatus of the invention has a fusion splice portion where respective ends of two optical fibers each having a core, a cladding, and a UV coat portion provided on the outside of the cladding are fusion spliced, and a re-coat portion which re-coats a portion where the UV coat portion is removed in the vicinity of the fusion splice portion is formed using a material capable of absorbing light radiated from the fusion splice portion. As a result light which is radiated from the fusion splice portion can be reliably prevented from coupling into another optical fiber adjacent to an outside of the re-coat portion.

Abstract: An optical apparatus which is reduced in the number of optical devices arranged on a main optical signal transmission path, thereby reducing the size and cost of the device, and which is improved in optical transmission quality. An optical amplifier includes an amplification medium, which is doped with an active material for optical amplification and to which pump light is introduced, for amplifying an optical signal to be output. A reflection-type variable optical attenuator includes a reflecting mirror for reflecting an input light to generate a reflected light, and a magneto-optical crystal arranged in a position where the input and reflected lights pass. The magneto-optical crystal is applied with a magnetic field to induce a Faraday rotation angle therein and thereby vary an attenuation amount of the amplified optical signal, and part of light transmitted through the reflecting mirror is converted, as input monitor light, into an electrical signal.

Abstract: An optical apparatus of the invention has a fusion splice portion where respective ends of two optical fibers each having a core, a cladding, and a UV coat portion provided on the outside of the cladding are fusion spliced, and a re-coat portion which re-coats a portion where the UV coat portion is removed in the vicinity of the fusion splice portion is formed using a material capable of absorbing light radiated from the fusion splice portion. As a result light which is radiated from the fusion splice portion can be reliably prevented from coupling into another optical fiber adjacent to an outside of the re-coat portion.

Abstract: An optical amplifier that improves the quality of WDM transmission by reducing four-wave mixing. An optical fiber has positive chromatic dispersion in a signal band and is used as an optical amplification medium for amplifying a wavelength division multiplex signal. An excitation section inputs excitation light to the optical fiber. In order to actualize mismatching of phases of optical signals with different wavelengths to be propagated, the optical fiber has positive chromatic dispersion in a signal band by which there is a great difference between a signal frequency, being a frequency of a signal to be amplified, and a zero-dispersion frequency, being a frequency at which chromatic dispersion is zero. As a result, the optical fiber functions as an optical amplification medium in which four-wave mixing is suppressed.

Abstract: An optical amplification device which includes first and second optical amplifiers, and a controller. The first optical amplifier receives a light and amplifies the received light. The second optical amplifier receives the light amplified by the first optical amplifier, and amplifies the received light. When a level of the light received by the first optical amplifier changes by ?, the controller controls a level of the light received by the second optical amplifier to change by approximately ??. In various embodiments, the controller causes the sum of the gains of the first and second optical amplifiers to be constant. In other embodiments, the optical amplification device includes first and second optical amplifier and a gain adjustor. The gain adjustor detects a deviation in gain of the first optical amplifier from a target gain, and adjusts the gain of the second optical amplifier to compensate for the detected deviation.

Abstract: An optical amplification device which includes first and second optical amplifiers, and a controller. The first optical amplifier receives a light and amplifies the received light. The second optical amplifier receives the light amplified by the first optical amplifier, and amplifies the received light. When a level of the light received by the first optical amplifier changes by ?, the controller controls a level of the light received by the second optical amplifier to change by approximately ??. In various embodiments, the controller causes the sum of the gains of the first and second optical amplifiers to be constant. In other embodiments, the optical amplification device includes first and second optical amplifier and a gain adjustor. The gain adjustor detects a deviation in gain of the first optical amplifier from a target gain, and adjusts the gain of the second optical amplifier to compensate for the detected deviation.

Abstract: An optical apparatus which is reduced in the number of optical devices arranged on a main optical signal transmission path, thereby reducing the size and cost of the device, and which is improved in optical transmission quality. An optical amplifier includes an amplification medium, which is doped with an active material for optical amplification and to which pump light is introduced, for amplifying an optical signal to be output. A reflection-type variable optical attenuator includes a reflecting mirror for reflecting an input light to generate a reflected light, and a magneto-optical crystal arranged in a position where the input and reflected lights pass. The magneto-optical crystal is applied with a magnetic field to induce a Faraday rotation angle therein and thereby vary an attenuation amount of the amplified optical signal, and part of light transmitted through the reflecting mirror is converted, as input monitor light, into an electrical signal.

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: Wavelength multiplexed light is amplified by first and second EDFs. Gains of the first and the second EDFs are respectively held to be predetermined values by first and second AGC circuits. Between the first and the second EDFs, a variable attenuator is arranged. A loss in the variable attenuator is controlled by an ALC circuit so that output power is held to be a predetermined value instructed by a supervisory control signal. Respective time constants of the first and the second AGC circuits are sufficiently short in comparison with the response times of the first and the second EDFs. The time constant of the ALC circuit is sufficiently long in comparison with the time period required to transmit the supervisory control signal to each optical node.

Abstract: An amount of ASE generated changes due to a temperature and a signal input power of an optical amplifying unit and causes a fluctuation of a gain of the optical amplifying unit. A photodiode on an input side and a photodiode on an output side detect input and output powers, and a temperature detecting unit detects a temperature of an optical amplifier. A control unit corrects the amount of ASE generated based on the detected input and output powers and the temperature according to AGC control. Driving of an excitation LD is controlled by a corrected result, and a gain of the optical amplifier is kept constant.