Abstract: A light source includes: a seed light source configured to output incoherent seed light with a predetermined bandwidth; and a booster amplifier that is a semiconductor optical amplifier configured to optically amplify the seed light input from a first facet, and output the amplified seed light as amplified light from a second facet, wherein the first facet and the second facet of the booster amplifier are subjected to a reflection reduction treatment, the booster amplifier is configured to operate in a gain saturated state, and relative intensity noise (RIN) and ripple are simultaneously suppressed in the amplified light.

Abstract: A light source for Raman amplification to Raman-amplify signal light includes: plural incoherent light sources that output incoherent light; plural pumping light sources that output second-order pumping light; an optical fiber for Raman amplification to Raman-amplify the incoherent light with the second-order pumping light, and outputs the amplified incoherent light; and an output unit connected to the optical transmission fiber, receiving the amplified incoherent light, and outputting the amplified incoherent light as first-order pumping light having a wavelength that Raman-amplifies the signal light to the optical transmission fiber.

Abstract: A light source for Raman amplification to Raman-amplify signal light includes: plural incoherent light sources that output incoherent light; plural pumping light sources that output second-order pumping light; an optical fiber for Raman amplification to Raman-amplify the incoherent light with the second-order pumping light, and outputs the amplified incoherent light; and an output unit connected to the optical transmission fiber, receiving the amplified incoherent light, and outputting the amplified incoherent light as first-order pumping light having a wavelength that Raman-amplifies the signal light to the optical transmission fiber.

Abstract: A light source for Raman amplification to Raman-amplify signal light includes: plural incoherent light sources that output incoherent light; plural pumping light sources that output second-order pumping light; an optical fiber for Raman amplification to Raman-amplify the incoherent light with the second-order pumping light, and outputs the amplified incoherent light; and an output unit connected to the optical transmission fiber, receiving the amplified incoherent light, and outputting the amplified incoherent light as first-order pumping light having a wavelength that Raman-amplifies the signal light to the optical transmission fiber.

Abstract: A light source for Raman amplification to Raman-amplify signal light includes: plural incoherent light sources that output incoherent light; plural pumping light sources that output second-order pumping light; an optical fiber for Raman amplification to Raman-amplify the incoherent light with the second-order pumping light, and outputs the amplified incoherent light; and an output unit connected to the optical transmission fiber, receiving the amplified incoherent light, and outputting the amplified incoherent light as first-order pumping light having a wavelength that Raman-amplifies the signal light to the optical transmission fiber.

Abstract: The present invention provides an optical demultiplexer module capable of narrowing the interval between wavelengths of divided light. The optical demultiplexer module is provided with an optical circulator (2) or a non-reciprocal optical branching device, the first and second optical waveguides (3) and (4) connected to the optical circulator or non-reciprocal optical branching device, and the second arrayed waveguide diffraction grating (6) connected to the second optical waveguide (4) and having a plurality of emitting ports (6a) through (6h). The first optical waveguide (3) has a plurality of filters (3a) through (3i) which reflects light of a specified wavelength to the second optical waveguide (4) via the optical circulator (2) or non-reciprocal optical branching device. In the second arrayed waveguide diffraction grating (6), the center wavelengths of light emitted from a plurality of emitting ports differ by an appointed frequency in terms of frequency.

Abstract: In an optical amplifier having a plurality of rare earth doped optical fibers in a multi-stage, there are provided one or more optical variable attenuator means, and an attenuation amount control means for changing an optical attenuation amount of the optical variable attenuator means on the basis of temperature of the rare earth doped optical fibers or an environmental temperature. In an optical amplifier having a plurality of rare earth doped optical fibers in a multi-stage, between the rare earth doped optical fibers, there are provided a replaceable optical part, one or more optical variable attenuator means, and an attenuation amount control means for changing an optical attenuation amount of the optical variable attenuator means on the basis of temperature of the rare earth doped optical fibers or an environmental temperature.

Abstract: An optical transmitter provided with a supercontinuum light source 4 which is composed of an optical amplifier 2 made by using a polarization maintaining amplification fiber 1 and a polarization maintaining fiber 3 which has a length of at least a specified value, is connected to the output side of the optical amplifier 2 and emits light having a continuous wave and a stable plane of polarization, a polarization maintaining optical demultiplexer 5 which takes out a light with a desired wavelength from the continuous wave light, and an external modulator 6 which superposes desired information upon the light with the desired wavelength.

Abstract: A method of manufacturing an optical filter that can restrain the wavelength dependence of the gain of an optical amplifier. The input signal light power, output power of pump light source (8), and the output signal light power of an optical amplifier (4) are set to the power values used for optical communication systems, and the total power of the simulation input light of a plurality of wavelengths (&lgr;1, &lgr;2, . . . &lgr;n) from light sources (1a) and an input light (probe light) from light sources (1m) are set equal to the total power of the input signals of a plurality of wavelengths used in wavelength division multiplex transmission systems.

Abstract: An optical fiber amplifier can maintain its optical power output above a level exceeding +20 dBm and a low noise figure if the input optical signal shows a high power level.

Abstract: A method to obtain polarization characteristics of an optical transmission medium is disclosed. Sequentially plural different states of polarized light are launched into the optical transmission medium. Intensities of light emerging from the optical transmission medium through combinations of optical elements are measured to obtain Stokes parameters from which Stokes vectors describing the emerging light corresponding to each of the plural sequentially launched states of polarization are obtained; for at least three different launched states of polarization, descriptors are used of these launched states of polarization and the Stokes vectors describing the corresponding emerging light to calculate a Jones matrix which mathematically models the changes that the launched light when described in terms of a Jones vector is subject to when passing through the optical transmission medium; and, the Jones matrix is used to describe the polarization characteristics of the optical transmission medium.

Abstract: A method of manufacturing an optical filter that can restrain the wavelength dependence of the gain of an optical amplifier. The input signal light power, output power of pump light source (8), and the output signal light power of an optical amplifier (4) are set to the power values used for optical communication systems, and the total power of the simulation input light of a plurality of wavelengths (.lambda.1, .lambda.2, . . . .lambda.n) from light sources (1a) and an input light (probe light) from light sources (1m) are set equal to the total power of the input signals of a plurality of wavelengths used in wavelength division multiplex transmission systems.

Abstract: An Er-doped optical fiber amplifier is adapted to increase the length of transmission path by raising the intensity of pumped light. In an Er-doped optical fiber amplifier 1 for amplifying signal light by means of an Er-doped optical fiber 7, using a 1,530 nm band pumping source 8, 1,530 nm band pumped light is Raman-amplified by a 1,430 nm-1,450 nm band light source 9 on the transmission path of an optical fiber 5.

Abstract: There is provided an optical telecommunications method that can externally modulate a plane of polarization without producing any null point. According to the invention, in an optical telecommunications system for externally modulating the plane of polarization of the light being transmitted through an optical fiber for the transmission of a polarized wave signal by externally applying a signal to modify the state of polarization, the source of light for the transmission of a polarized wave signal is a fiber ring laser.

Abstract: An apparatus and method for optical telecommunication includes introducing a laser beam emitted from a light source at a first station into an optical fiber, providing an ultrasonic wave obtained by modulating a voice signal by a signal-applying-device at a work section to the optical fiber, modulating a polarized light passing through the optical fiber in amplitude and frequency, receiving the polarized light with the shifted wave plane at a light-receiving section in a second station, detecting at the light-receiving section in the second station the polarized light which has been modulated by the signal-applying device in the work section, and demodulating the polarized light to obtain a voice signal.

Abstract: A technique for identifying an optical transmission medium from a plurality of single-mode-type optical transmission media by using longitudinal middle portions of the media as an identification section by first exciting a particular optical transmission media by means of a polarized light, next applying either an electromagnetic action or a mechanical action to the particular optical transmission medium to modulate the polarized light and then identifying the particular optical transmission medium based on the deviation of the polarized plane of the polarized light.