Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.

Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.

Abstract: A tunable multimode wavelength division multiplex Raman pump and amplifier, and a system, method, and computer program product for controlling a tunable Raman pump and amplifier. The tunability of the pump source is accomplished by either straining or heating an external fiber grating, thereby causing a different wavelength of light to be emitted by the pump source. The system includes a microprocessor-based controller that monitors an amplifier's performance and adjusts the drive current and/or wavelength of the tunable pumps of an amplifier to achieve a target performance.

Abstract: An optical signal amplifier includes a light source, a depolarizer, and a gain medium that transfers energy from a pump beam output from the depolarizer to the optical signal. The depolarizer may include one or more birefringent optical fibers which support two polarization modes, a fast mode and a slow mode. The light propagates in the fast mode at a higher velocity than the light propagates in the slow mode so as to impart phase delay as the light propagates in the birefringent optical fibers, thereby at least partially depolarizing the beam. A method for using the amplifier with different types of transmission fibers enables the matching of depolarizers with relatively high percentage of degree of polarization, depending on fiber type, while staying below polarization dependent gain requirements.

Abstract: An optical transmission system is provided in which a plurality of Raman amplifiers are combined so that the wavelength band of a first Raman amplifier in the form of an upward convex curve including the maximum gain value and the wavelength band of a second Raman amplifier in the form of a downward convex curve including the minimum gain value overlap with each other, and that the wavelength band of the first Raman amplifier in the form of a downward convex curve including the minimum gain value and the wavelength band of the second Raman amplifier in the form of an upward convex curve including the maximum gain value overlap with each other. This arrangement also applies to cases where three or more amplifiers are used. Due to this arrangement, an optical transmission system is realized in which it is possible to attain a reduction in Raman gain flatness without using any means such as an equalizer.

Abstract: In a Raman amplifier using three or more pumping wavelengths, when the pumping wavelengths are divided into a short wavelength side group and a long wavelength side group at the boundary of the pumping wavelength having the longest interval between the adjacent wavelengths, the short wavelength side group includes two or more pumping wavelengths having intervals therebetween which are substantially equidistant, and the long wavelength side group is constituted by two or less pumping wavelengths.

Abstract: A Raman amplifier, system and method using a plurality of pumps configured to pump light into an optical fiber so as to Raman-amplify an optical signal propagating through the optical fiber. The Raman amplifier also includes an optical coupler configured to optically interconnect the pumping device with the optical fiber, and a control unit configured to control the pumping device so as to achieve a target amplification performance. Further, the control unit monitors the Raman-amplified WDM signal and determines if the monitored Raman-amplified WDM signal is within an allowable tolerance of the target amplification performance. If the Raman-amplified signal is not within the allowable tolerance, the control unit actively controls the pumps to bring the monitored Raman-amplified signal within the allowable tolerance of the target amplification profile.

Abstract: A memory device which prevents lowering of processing efficiency of the entire system during processing for encryption or decryption of data. The first memory circuit stores data which is inputted through an external-bus-connection terminal. The second memory circuit is internally connected to the first memory circuit, acquires a duplicate of the data stored in the first memory circuit, and stores the duplicate of the data. The encryption/decryption circuit is internally connected to the second memory circuit, performs processing for encryption or decryption of the duplicate of the data stored in the second memory circuit, in response to an input of designation of an operation, and returns a result of the processing to the second memory circuit.

Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.

Abstract: A tunable multimode wavelength division multiplex Raman pump and amplifier, and a system, method, and computer program product for controlling a tunable Raman pump and amplifier. The tunability of the pump source is accomplished by controlling the optical output and central wavelengths of tunable semiconductor laser devices. The system includes a microprocessor-based controller that monitors an amplifier's performance and adjusts the drive current and/or wavelength of the tunable pumps of an amplifier to achieve a target performance.

Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.

Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.

Abstract: First pump light for Raman-amplifying optical signal is inputted to the output end of the optical signal, and second pump light used for Raman-amplifying the first pump light and having a wavelength shorter than that of the first pump light is inputted to the input end of the optical signal. The second pump light is also inputted to the output end of the optical signal. The first pump light is also inputted to the input end of the optical signal. The Raman amplification band of the second pump light is made not to be overlapped with that of the optical signal. The wavelength of the second pump light is shorter than that of the first pump light by the Raman shift of the amplifier fiber. The light source of either the first or second pump light or both the light sources of them are multiplex optical sources. The first pump light is emitted from a semiconductor laser. Third pump light for Raman-amplifying the second pump light is directed to an optical transmission line.

Abstract: A tunable multimode wavelength division multiplex Raman pump and amplifier, and a system, method, and computer program product for controlling a tunable Raman pump and amplifier. The tunability of the pump source is accomplished by either straining or heating an external fiber grating, thereby causing a different wavelength of light to be emitted by the pump source. The system includes a microprocessor-based controller that monitors an amplifier's performance and adjusts the drive current and/or wavelength of the tunable pumps of an amplifier to achieve a target performance.

Abstract: An optical signal amplifier comprises a light source, a depolarizer, and a gain medium that transfers energy from a pump beam output from the depolarizer to the optical signal. The depolarizer may comprise one or more birefringent optical fibers which support two polarization modes, a fast mode and a slow mode. The light propagates in the fast mode at a higher velocity than the light propagates in the slow mode so as to impart phase delay as the light propagates in the birefringent optical fibers, thereby at least partially depolarizing the beam.

Abstract: A Raman amplifier, system and method using a plurality of pumps configured to pump light into an optical fiber so as to Raman-amplify an optical signal propagating through the optical fiber. The Raman amplifier also includes an optical coupler configured to optically interconnect the pumping device with the optical fiber, and a control unit configured to control the pumping device so as to achieve a target amplification performance. Further, the control unit monitors the Raman-amplified WDM signal and determines if the monitored Raman-amplified WDM signal is within an allowable tolerance of the target amplification performance. If the Raman-amplified signal is not within the allowable tolerance, the control unit actively controls the pumps to bring the monitored Raman-amplified signal within the allowable tolerance of the target amplification profile.

Abstract: In a Raman amplifier using three or more pumping wavelengths, when the pumping wavelengths are divided into a short wavelength side group and a long wavelength side group at the boundary of the pumping wavelength having the longest interval between the adjacent wavelengths, the short wavelength side group includes two or more pumping wavelengths having intervals therebetween which are substantially equidistant, and the long wavelength side group is constituted by two or less pumping wavelengths.

Abstract: Wavelength multiplex transmission is realized in which the temperature dependency of an EDFA is compensated for in relation to the wavelengths which are used. A first and a second long-period grating which have different periods from each other are formed in an optical fiber, ensuring that the peak wavelength of a waveform representing an optical transmission loss characteristic of the first long-period grating side is located on the shorter wavelength side than a transmission band and a peak wavelength of a waveform representing an optical transmission loss characteristic of the second long-period grating side is located on the longer wavelength side within the transmission band.

Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.

Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.