Abstract: An L band optical amplifier in disclosed. The optical amplifier includes a signal line which has an input, an output disposed optically downstream of the input, and an amplifying gain medium optically disposed between the input and the output. The optical amplifier further includes a laser optically connected to the first amplifying gain medium and an apparatus for directing C band light into the amplifying gain medium.

Abstract: A Raman amplifier assembly includes a Raman amplifier configured to receive a signal from a signal source. The signal travels in an upstream direction in the Raman amplifier. A first pump source is coupled to the Raman amplifier. The first pump source produces a first pump beam that travels in a downstream direction and is counter-propagating relative to the signal. A second pump source is coupled to the Raman amplifier and produces a second pump beam that travels in the upstream direction. The second pump source has an average relative intensity noise of less than −80 dB/Hz.

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: An optical amplifier is provided comprising an optical fiber ring, and a pump light emitting device providing a primary pump wavelength. The pump light emitting device is optically coupled to the optical fiber ring and utilizes the primary pump wavelength to generate a secondary pump wavelength. Optical signal amplification and secondary pump wavelength lasing occur within the same section of the optical fiber ring.

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: In a first aspect, a Raman amplifier is pumped using pumps just above and below the fiber water peak. This enables lower power pumps to be used, as the high attenuation is avoided. In a second aspect, a first pump provides a signal having a first wavelength and a first power, and a second pump source provides a plurality of signals, each having a power lower than the first power and a wavelength in a range approximately one Stokes shift higher than the first wavelength. In this way, the second pump source signals are amplified by the Raman effect by the first pump source signal, and the amplified second pump source signals cause signal amplification. The amplified second pump source signals can then include wavelengths above and below the water peak.

Abstract: The present invention is aimed at providing an optical repeater using Raman amplification that can Raman amplify WDM signal lights propagated through a plurality of transmission systems, with high excitation efficiency and stability. To this end, an optical repeater using Raman amplification of the present invention multiplexes and demultiplexes excitation lights supplied from a plurality of excitation light sources in a star coupler and then supplies the resultant demultiplexed lights to Raman amplification media of a plurality of transmission systems via optical multiplexers, to thereby Raman amplify the WDM signal lights of the respective transmission systems. Moreover, by feedback controlling the power of each excitation light based on the result of monitoring the WDM signal light power after Raman amplification in each transmission system, a stabilized Raman amplification operation with reduced dispersion in the power of each excitation light output from the star coupler is realized.

Abstract: An optical amplifying unit includes an input for the input optical signals and an output for the output of the optical signals. A single-mode active fiber codoped with Er and Yb is optically connected to the input and the output and adapted to amplify the optical signals. A first pump source generates a first pump radiation including an excitation wavelength for Er, and a second pump source for generates a second pump radiation including an excitation wavelength for Yb. A first optical coupler optically couples the first pump radiation into the core of the active fiber in a co-propagating direction with respect to signal direction, and a second optical coupler optically couples the second pump radiation into the core of the active fiber in a counter-propagating direction with respect to signal direction.

Abstract: An amplified broadband optical signal is produced in a transmission system. An optical signal is divided into a first beam and a second beam. The first beam has a wavelength less than a predetermined wavelength. The second beam has a wavelength greater than the predetermined wavelength. The first beam is directed to a transmission link in the transmission system. The transmission system includes a distributed Raman amplifier. The distributed Raman amplifier operates in the wavelength range less than 1480 nm. The second beam is directed to a second amplifier. The first and second beams are combined. An amplified broadband optical signal is produced.

Abstract: An apparatus and method are described for exploiting almost the full almost 25TH% of bandwidth available in the low-loss window in optical fibers (from 1430 nm-1620 nm) using a parallel combination of optical amplifiers. The low-loss window at about 1530 nm-1620 nm can be amplified using erbium-doped fiber amplifiers (EDFAs). However, due to the inherent absorption of the erbium at shorter wavelengths, EDFAs cannot be used below about 1525 nm without a significant degradation in performance. For the low-loss window at approximately 1430-1530 nm, amplifiers based on nonlinear polarization in optical fibers can be used effectively. A broadband nonlinear polarization amplifier (NLPA) is disclosed which combines cascaded Raman amplification with parametric amplification or four-wave mixing. In particular, one of the intermediate cascade Raman order wavelengths &lgr;r should lie in close proximity to the zero-dispersion wavelength &lgr;0 of the amplifying fiber.

Abstract: An optical transmission system is provided comprising a thulium doped optical fiber, a light emitting pump device optically coupled to the thulium doped fiber, and a Raman amplifier fiber optically coupled to the thulium doped optical fiber. The light emitting pump device in combination with the thulium doped fiber generates a first amplification pump wavelength and the Raman amplifier receives the first amplification pump wavelength. The first pump wavelength amplifies an optical signal in the Raman amplifier, the Raman amplifier operating at a signal wavelength in the range of about 1530 nm to about 1625 nm.

Abstract: An improved long wavelength-band EDFA (L-band EDFA) is disclosed. The EDFA includes an input terminal for receiving signal light, a pumping unit for pumping a 1,530 nm wavelength band pumping light, a WDM coupler for multiplexing the signal light and the pumping light, and an EDF pumped by a 1,530 nm wavelength band pumping light for amplifying the signal light. Compared with conventional 1,480 nm pumping, the EDFA pumped by 1,530 nm band pumping have about two times higher power conversion efficiency.

Abstract: An optical transmission system includes an optical transmitting unit (10) to transmit optical signals in a transmission wavelength band above 1570 nm; an optical receiving unit to receive the optical signals; an optical fiber link optically coupling the transmitting unit to the receiving unit, at least an optical amplifying unit (100) coupled along the link and adapted to amplify the optical signals; the optical amplifying unit (100) having an amplification wavelength band including the transmission wavelength band and comprising: an input (101) for the input of the optical signals, an output (102) for the output of the optical signals, at least an erbium-doped active fiber (103a, 103b) for the amplification of the optical signals, having a first end optically coupled to the input (101) and a second end optically coupled to the output (102), a pump source (104, 106) for generating a pump radiation having a wavelength greater than 1400 nm and lower than 1470 nm, and an optical coupler (105, 107) optically coup

Abstract: A Raman amplifier providing a wideband gain for use in a wavelength division multiplexing (WDM) optical communication system. In one embodiment, a first optical amplifier Raman amplifies a wavelength division multiplexed signal light in both a first wavelength band and a second wavelength band in accordance with a plurality of excitation (pumping) lights provided to the first optical amplifier, the first and second wavelength bands being different from each other. A divider divides the amplified signal light into first and second lights in the first and second wavelength bands, respectively. A second optical amplifier amplifies the first light and has a gain band in the first wavelength band. The third optical amplifier amplifies the second light and has a gain in the second wavelength band. In various embodiments, a gain equalizer and/or an optical isolator is used in combination with the first optical amplifier providing the Raman amplification.

Abstract: An L band optical amplifier in disclosed. The optical amplifier includes a signal line for transmitting a light signal in a first direction. The signal line has an input, an output disposed optically downstream of the input, and an amplifying gain medium optically disposed between the input and the output. The optical amplifier further includes a laser optically connected to the first amplifying gain medium and an apparatus for directing C band light generated in a second direction, opposite the first direction, into the amplifying gain medium.

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 dynamically optimized photonic waveshifting multiplexer apparatus receives a photonic signal of a first wavelength and bandwidth, and outputs a photonic signal of a second stabilized wavelength and bandwidth. The apparatus measures selected photonic signal parameters dynamically and extracts signal quality information therefrom. This signal quality information is used for self-calibration and to optimize and control signal quality of the photonic output signal.

Abstract: A Raman amplifier applicable to a wavelength division multiplexing optical transmission system is proposed. The Raman amplifier, which can make good use of a wavelength range, comprises an optical fiber for Raman amplification and a pump light introducing means. The zero-dispersion wavelength of the optical fiber and the wavelength of the pump light are nearly equal. The wavelength of pump light is preferably in the range where the absolute magnitude of the chromatic dispersion of the optical fiber is less than 0.3 ps.nm−1.km−1. A range near a zero-dispersion wavelength cannot be utilized as a signal range because waveform deterioration of signal light occurs due to four wave mixing. This range can be utilized effectively as a wavelength range of exciting light for Raman amplification.

Abstract: In an optical amplifier evaluation instrument, a rectangular spectrum light source 1 transmits continuous light having a wide-band and flat spectrum shape, a first optical modulator 2 receives and pulse-modulates the continuous light. Further, a second optical modulator 3 operates in the same period as the first optical modulator 2 and performs the on/off pulse operation, thereby providing a sampling window in a time domain for extracting and suppressing an optical signal. A modulation signal generation section 4 performs such control and drive. An optical signal undergoing pulse intensity modulation is input to a measured optical amplifier 6. Post-amplified signal light power for each frequency component and amplified spontaneous emission power for each frequency component in a time domain in which no optical pulse signal exists are measured and operations are performed for each wavelength.

Abstract: An optical amplifier comprises a trivalent thulium-doped optical fiber; a first pump light emitting device optically coupled to the fiber for generating a primary pump source at a first wavelength, and a second pump light emitting device optically coupled to the fiber for generating a secondary pump source at a second wavelength. In a preferred aspect of the present invention, the amplifier also includes a third (auxiliary) pump light emitting device optically coupled to the fiber for generating a third pump source at a third wavelength. Each of the amplification signals comprise at least one pre-selected wavelength. The first amplification signal has a wavelength pre-selected to provide a reduced noise figure for the amplifier. The second amplification signal has a wavelength pre-selected to increase the optical efficiency of the amplifier. The third amplification signal can have a wavelength pre-selected to populate the 3F4 energy level of the fiber, and to minimize depletion of the 3H6 ground state.

Abstract: A method and apparatus to amplify an optical signal is described. A first filter splits an optical signal into a first and second parts. A first raman amplifier amplifies the first part. A second raman amplifier amplifies the second part. A combiner combines the amplified first and second parts.

Abstract: Optical amplifiers are provided in which optical gain is produced by Raman pumping fiber. The Raman-pumped fiber may be a span of transmission fiber or a coil of fiber in a discrete amplifier. Raman pump light may be provided using laser diodes operating at different wavelengths. The Raman pump light that is produced by the laser diodes may be modulated to reduce pump interactions in the fiber. Raman pump light may be modulated by directly modulating the laser diodes or by using optical components that modulate constant power pump light from the laser diodes.

Abstract: A light source apparatus suitable for use for evaluation of an optical device and for production of pump light for an optical amplifier. The apparatus includes a light emitting element having a gain band and a band reflection filter optically connected to the light emitting element. The light emitting element outputs a light beam having a spectrum which is determined by the gain band. The filter produces, from the light beam outputted from the light emitting element, a transmission beam and a reflection beam which returns to the light emitting element. The filter has a reflection band included in the gain band of the light emitting element and narrower than the gain band, and the transmission beam of the filter has a maximum power higher than the maximum power of the light beam to be outputted from the light emitting element. With the construction, pump light having a maximum power higher than the maximum power of the light to be outputted from the light emitting element can be obtained.

Abstract: An optical amplifier comprises an optical fiber segment doped with impurity ions such as erbium for providing optical gain for an optical signal propagating in the optical fiber segment. A first source of a first pumping wavelength pumps the ions from a first ground state to a second metastable state. The metastable state decays to the ground state by stimulated emission to provide the optical gain. A second source of a second pumping wavelength pumps the ions from the ground state to a third auxiliary state. The auxiliary state decays to the metastable state. Thus, by controlling the pumping power in one or both pumping wavelengths, it is possible to control the fraction of ions in the metastable state. This in turn permits control of an overall scale factor of the gain spectrum without substantially affecting the shape of the gain spectrum.

Abstract: Multiwavelength Raman pumps for Raman amplifiers are provided. The multiwavelength Raman pumps may be based on semiconductor devices that have multiple source regions, each of which handles pump light at a different wavelength. An optical coupler such as a lens and isolator arrangement or an integral fiber lens may be used to couple pump light from the multiwavelength Raman pump into a fiber. A depolarizer may be used to depolarize the Raman pump light provided by the Raman pump. Gratings may be used to define the lasing wavelengths for the Raman pump. A number of tunable sources may be used on the semiconductor device. A fiber Bragg grating may be used to form an external cavity or coupled cavity arrangement for the semiconductor device.

Abstract: The dual wavelength pumping scheme controls the relative population of the termination state vis-a-vis the metastable state. Praseodymium doped chalcogenide glass and a variety of thulium doped glasses are described as examples. The relative pump powers or wavelengths may be adjusted to control the gain spectrum of the amplifier, making the amplifier useful in a variety of different optical systems including wavelength division multiplexed systems.

Abstract: A method and apparatus is provided for pumping an active medium in an optical amplifier. The active medium substantially maximizes amplification when pumped at a pump wavelength. If the active medium is erbium, for example, a pump wavelength of 980 nm may be employed. The apparatus includes a plurality of fiber Bragg grating lasers operating in a regime of coherence collapse. Each of the lasers generate optical energy at a different wavelength, which are distributed about the pump wavelength. The apparatus also includes optical components for combining the different wavelengths to form a pump beam and a coupler for coupling the pump beam to the active medium.

Abstract: Optical systems of the present invention include a plurality of optical processing nodes in optical communication via at least one signal varying device. The signal varying devices includes an optical fiber suitable for facilitating Raman scattering/gain in a signal wavelength range and a pump energy source for providing pump energy in a plurality of pump wavelengths. The pump source provides sufficient pump energy in each pump wavelength to stimulate Raman scattering/gain in the optical fiber within the signal wavelength range. The pump wavelengths are selected such that the combined Raman gain resulting from the pump energy supplied by each pump wavelength produces a desired signal variation profile in the signal wavelength range. In addition, the pump energy supplied by at least one of the pump wavelengths can be varied to produce a controlled signal intensity variation profile over the signal wavelength range in the optical fiber.