Abstract: An optical fiber amplifier having higher gain and lower noise than a prior art fiber amplifier when both amplifiers employ an equal length of gain medium-containing optical fiber and an equal intensity of pumping light. The optical fiber amplifier of the present invention comprises: a length of optical fiber containing a gain medium; a circulator, connected to one end of the optical fiber, that introduces optical signals into the optical fiber and outputs the optical signals amplified at the optical fiber to its output port; optical pumping means, connected to the other end of the optical fiber, for applying pumping light to the optical fiber in order to amplify the introduced optical signals; and a two-port wavelength selective coupler, disposed between the other end of the optical fiber and the optical pumping means, that passes pumping light from the optical pumping means and reflects back the amplified optical signals from the optical fiber.

Abstract: A long-band (L-band) light source capable of testing the characteristics of optical elements using a feedback loop in a fiber amplifier of an optical communication system.

Abstract: Disclosed is a long-band (L-band) fiber amplifier using a feedback loop which includes a rare earth doped fiber as an amplification medium, forward and backward pump laser diodes, positioned on front and rear ends of the rare earth doped fiber, respectively, for generating pumping lights, first wavelength selective couplers for providing the pumping lights from the pump laser diodes to the rare earth doped fiber, optical isolators, inserted into front and rear ends of the first wavelength selective couplers, respectively, for intercepting backward propagation of signal lights reflected from input and output terminals of the fiber amplifier, a feedback loop for making a seed beam incident to the rare earth doped fiber or making an amplified spontaneous emission (ASE) incident again to the rare earth doped fiber, second wavelength selective couplers, provided between the optical isolators and the first wavelength selective couplers, respectively, for making the seed beam incident to the feedback loop or extract

Abstract: Disclosed is a broadband light source for measurement using a seed-beam which can reduce the strength difference between the output lights per wavelength by heightening the strength of the output light corresponding to the L-band of the light source, and thus reduce the measurement error per wavelength. The broadband light source includes a seed-beam light source for outputting a seed-beam of a predetermined band of wavelength, a first optical coupler for combining the seed-beam and a pumping light and making a combined light incident to a front of a rare earth ion-doped optical fiber, a first pumping light source for providing the pumping light to the first optical coupler, a second optical coupler for making the input pumping light incident to a rear of the rare earth ion-doped optical fiber, a second pumping light source for providing the pumping light to the second optical coupler, and an output terminal for radiating the light outputted through the rear of the rare earth ion-doped optical fiber.

Abstract: A method and apparatus for amplifying the optical signals of a C-band (1550 nm wavelength band) and a L-band (1580 nm wavelength band) in a wide-band optical fiber amplifier, wherein the incoming optical signals are separated into the 1550 nm wavelength band and the 1580 nm wavelength band by a WVDM optical coupler and respectively amplified by a C-band EDFA and a L-band EDFA A backward ASE generated by the C-band EDFA is fed back to the L-band EDFA by a circulator as a supplementary pumping light to the amplification of the optical signals of the 1580 nm wavelength band.

Abstract: A L-band(long-band) optical fiber amplifier is provided. The L-band optical fiber amplifier includes an optical fiber doped with a rare-earth element, at least one pumping light source for emitting pumping light to the optical fiber, a seed beam source for emitting a seed beam at a predetermined wavelength band, and a seed beam coupler disposed between an input terminal and the optical fiber, for coupling an input optical signal with the seed beam and feeding the coupled light forward to the optical fiber. By use of the seed beam, the L-band optical fiber amplifier improves gain flatness characteristics at wavelengths of an optical signal and increases amplification efficiency when the length of the optical fiber and the intensities of the optical signal and the pumping light are changed.

Abstract: An optical fiber amplifier including a first optical fiber doped with erbium and phosphorous, for amplifying signal light excited by the erbium, a second optical fiber connected to one end of the first optical fiber, doped with erbium and aluminum, and having a gain spectrum slope opposite to the first optical fiber according to population inversion of the erbium, for amplifying signal light output by the first optical fiber, a pumping laser source connected to another end of the first optical fiber, for exciting the erbium of the first and second optical fibers, and a light coupler for coupling pumping light from the pumping laser source to the signal light and outputting the resultant light to the first optical fiber. Two types of EDFs (erbium doped fibers) having different gain spectrums are used, such that the gain spectrum of each of the EDFs actively varies with the input signal light power or pumping light power. Thus, an entirely flat gain is kept.

Abstract: A wavelength division multiplexing erbium doped fiber amplifier (WDM-EDFA) which outputs constant power per channel, and an amplification method thereof, are provided.

Abstract: An optical fiber amplifier capable of having a flattened gain irrespective of the intensity of an input signal light. The optical fiber amplifier includes a first amplifying unit for amplifying an input signal light using a first pumping light to obtain a predetermined gain, a second amplifying unit for re-amplifying the signal light amplified by the first amplifying unit, using a second pumping light, to obtain the same gain as the predetermined gain, and a pumping light separating unit for allowing the amplified signal light outputted from the first amplifying unit to enter the second amplifying unit while preventing the first pumping light from reaching the second amplifying unit and preventing the second pumping light from reaching the first amplifying unit, whereby the amplified signal light entering the second amplifying unit is allowed to be amplified only by the second pumping light.

Abstract: An optical fiber amplifier for controlling gain flatness including an optical fiber amplifying unit for amplifying input signal light according to a predetermined amplification control value, a measuring unit for measuring the power level of amplified spontaneous emission (ASE) at a predetermined wavelength band output from the optical fiber amplifying unit, and a gain controller for controlling the amplification control value of the optical fiber amplifying unit according to the measured power level of the ASE to flatten the gain of the optical fiber amplifying unit. The gain flatness of amplified signal light is monitored and controlled, thereby obtaining gain-flattened signal light even when power level of signal light varies from wavelength to wavelength.

Abstract: An optical fiber amplifier having constant output power for each channel including a first measuring unit for dividing an input light signal into a first light signal and a second light signal, sub-dividing the first light signal into a plurality of light signals and converting the plurality of light signals into electrical signals to output the electrical signals, an optical fiber amplifying unit for amplifying the second light signal according to a predetermined amplification control value, a second measuring unit for converting a light signal of a predetermined wavelength band, output from the optical fiber amplifying unit, into an electrical signal, and an output power controller for controlling the predetermined amplification control value according to a plurality of output values of the first measuring unit and an output value of the second measuring unit, so that the power level of the optical fiber amplifying unit is maintained at a constant level.