Abstract: The present invention relates to an optical fiber for amplification, an optical amplifying apparatus, and so on, having a structure for enabling increase of power of output light, suppression of occurrence of nonlinear optical phenomena, and compact storage all together. The optical amplifying apparatus comprises an optical fiber for amplification amplifying input light inputted together with pumping light from a pumping light source. The optical fiber for amplification comprises a core region doped with a rare-earth element, and a cladding region provided on an outer periphery of the core region and having a refractive index lower than that of the core region. The core region has an outer diameter of 10 ?m or more but 30 ?m or less, and has a relative refractive index difference of 0.5% or more but 2.0% or less with respect to the cladding region. The cladding region has an outer diameter of 75 ?m or more but 200 ?m or less.

Abstract: A laser light source includes a light source section for outputting pulse laser light ?1, ?2 with a mutually identical repetition frequency, an optical amplification section for amplifying and outputting the pulse laser light ?1, ?2 output from the above light source section by means of a common optical amplification medium, an optical demultiplexing section for mutually demultiplexing pulse laser light ?1, ?2, an optical multiplexing section for multiplexing and outputting the pulse laser light ?1, ?2 demultiplexed in the above optical demultiplexing section, and an optical path length difference setting section for adjusting an optical path length difference between the pulse laser light ?1, ?2 in between the optical demultiplexing section and the optical multiplexing section.

Abstract: The present invention relates to an optical gain waveguide having excellent gain flatness in C-band, and excellent tolerance against variations of a pumping light wavelength as well, and a method of controlling the same. The optical gain waveguide includes an optical waveguide region which is doped with Er element which can be pumped by irradiating pumping light with a wavelength of 976 nm or less, or a wavelength of 981 nm or more. A population inversion of Er is optimized so that a gain variation in the C-band becomes minimum, by the irradiation of the pumping light. At this time, a relative gain variation of the optical gain waveguide, which is defined by a peak gain value and a minimum gain value in the wavelength region of 1,530 nm to 1,560 nm becomes smaller than 11.5%. In addition, in the optical gain waveguide, a width of wavelength range producing the relative gain variation smaller than 11% is 36 nm or more.

Abstract: There is disclosed a laser processing device, comprising: a laser light source for emitting laser light; an irradiating optical system for irradiating laser light emitted from the laser light source substantially perpendicularly onto a processing surface of an object to be processed; a reflected light monitoring unit for monitoring the intensity of light reflected from the processing surface which is being irradiated with the laser light from the irradiating optical system; a thermal radiation monitoring unit for monitoring the intensity of thermal radiation generated at the processing surface which is being irradiated with the laser light from the irradiating optical system; and a controller for controlling output of laser light from the laser light source, wherein the controller determines abnormality and either one of reduces and stops output of laser light from the laser light source when the intensity of reflected light monitored by the reflected light monitoring unit drops below a first prescribed value

Abstract: There is disclosed a photodetection device comprising: a photodetector having detection sensitivity at a first wavelength; a first optical fiber propagating light in a plurality of modes at the first wavelength, the first optical fiber having an entrance end on which light at the first wavelength falls; and a second optical fiber propagating light in a plurality of modes at the first wavelength, the second optical fiber having a product of a core diameter and a numerical aperture at the first wavelength that is greater than a product of a core diameter and a numerical aperture at the first wavelength of the first optical fiber, the second optical fiber having one end and another end, the second optical fiber being optically coupled to the first optical fiber at the middle of the first optical fiber in a longitudinal direction of the first optical fiber, and the one end of the second optical fiber being optically coupled to the photodetector.

Abstract: The present invention relates to an optical amplifier (TDFA) having a configuration which enables to reduce temperature dependence of the gain with reduced power consumption and simple control. The optical amplifier includes, in the order from an input port to an output port, an optical isolator, an optical coupler, an optical amplification fiber, an optical coupler, an optical isolator, an optical gain equalizing filter, a variable optical attenuator, an optical isolator, an optical coupler, an amplification fiber, an optical coupler, and an optical isolator. At least a core region of the optical amplification fiber is doped with Tm element, and signal light in a predetermined wavelength range is amplified by supply of pumping light. The gain equalizing fiber has a loss spectrum which shifts toward the short wavelength side as the temperature of the optical waveguide is higher, thereby equalizing the optical amplification gain of the signal light in the optical amplification fiber.

Abstract: The present invention relates to an optical amplifier (TDFA) or the like comprising a structure for constantly keeping the power of outputted signal light and gain flatness even when the power or number of channels of input signal light fluctuates. In this optical amplifier, the pumping light outputted from each pumping light source is forwardly or backwardly supplied to an optical amplification fiber. The signal light inputted from an input port is amplified by the optical amplification fiber, and thus amplified light is outputted from an output port. An optical add/drop coupler causes a part of the light outputted from the optical amplification fiber to branch out, whereby its power is monitored by an output light monitor system at two or more wavelengths. According to thus obtained results of monitoring, a controller adjusts the pumping light outputted from each pumping light source.

Abstract: The present invention relates to an optical component and others in structure capable of implementing improved compensation for a gain slope. The optical component is equipped with first and second Mach-Zehnder interferometers. The first Mach-Zehnder interferometer is provided with a first temperature controller for controlling a temperature of at least one of a part of an optical main path and a first optical side path, while the second Mach-Zehnder interferometer 42 is also provided with a second temperature controller for controlling a temperature of at least one of a part of the optical main path and a second optical side path.

Abstract: There is disclosed a method of manufacturing an optical fiber whose core is made of multi-component glass without fluctuation in its outer diameter and occurrence of sudden breakage thereof, with a technique of unifying a core rod and a cladding tube at the time of drawing, and yet drawing them; and the optical fiber having a multi-component glass core are disclosed.

Abstract: The present invention relates to an optical waveguide and the like having a structure for generating a wide band of ASE. The optical waveguide comprises a material mainly comprised of glass or glass ceramics, and is at least partly doped with a rare earth element. In a spectrum of ASE generated in the optical waveguide when supplied with pumping light having a single wavelength in particular, a 15-dB band or 10-dB band includes a range from 1.45 ?m to 1.65 ?m or a range from 1.5 ?m to 1.7 ?m. Alternatively, a 3-dB band includes S, C, and L bands.

Abstract: The present invention provides a Raman amplifier and the like comprising a structure for keeping the flatness of power spectrum of Raman-amplified signal light. The Raman amplifier comprises an optical fiber for Raman-amplifying a plurality of signal channels of signal light having respective center optical frequencies different from each other; a pumping light supply section for supplying N (N being an integer of 2 or more) pumping channels of pumping light having respective center optical frequencies different from each other to the optical fiber; and a feedback section for detecting a part of the signal light Raman-amplified within the optical fiber when the pumping light is supplied thereto, and controlling the pumping light supply section such that the Raman-amplified signal light has a substantially flat power spectrum with respect to an optical frequency direction according to the result of detection.

Abstract: An optical amplifier 1 is constructed using an amplification optical waveguide in which a first amplification optical fiber 10 and a second amplification optical fiber 20 are connected in series. A P/Al-codoped EDF 10 excellent in noise characteristics is applied to the upstream first amplification optical fiber 10, and an EDF 20 such as an Al-doped EDF or the like is applied to the downstream second amplification optical fiber 20. This realizes the optical amplifier 1, and the optical transmission system using it, capable of amplifying the signal light in the signal light wavelength band of not less than the wavelength of 1570 nm including the L-band wavelength band of wavelengths from 1570 to 1600 nm, with good gain characteristics and achieving the improvement in the noise characteristics.

Abstract: The present invention relates to an optical amplification fiber and others capable of effectively reducing nonlinear interaction between signal channels even in transmission of multiplexed signal light containing multiple signal channels arranged in high density and also effectively reducing bending loss. An optical amplification module has an optical isolator, a WDM coupler, an Er-doped optical fiber (EDF) as an optical amplification fiber, a WDM coupler, and an optical isolator, which are arranged in order on a signal light propagation path from an input connector to an output connector, and further has a pumping light source connected to the WDM coupler and a pumping light source connected to the other WDM coupler. The EDF, at the wavelength of 1607 nm, has a mode field diameter (MFD) of 10 ?m or more to the fundamental mode and a MAC number (=MFD/cutoff wavelength) of 6.8 or less to the fundamental mode.

Abstract: An optically amplifying waveguide that can have a gain having a small wave-length dependency in a wavelength range shorter than the C-band, and the like. The optical amplifier module 1 optically amplifies a signal lightwave that has a wavelength lying in a wavelength range of 1,490 to 1,530 nm and that has entered an input connector 11 to output the optically amplified signal lightwave from an output connector 12. An optical isolator 21, a WDM coupler 31, an Er-doped optical fiber (EDF) 50, a WDM coupler 32, and an optical isolator 22 are provided in this order on a signal lightwave-transmitting path from the input connector 11 to the output connector 12. A pump source 41 connected to the WDM coupler 31 and a pump source 42 connected to the WDM coupler 32 are also provided. In the EDF 50, at least one of the stimulated-emission cross section and the absorption cross section assumes a maximum value at the shorter-wavelength side of a peak at a wavelength range of 1.53 ?m.

Abstract: The present invention relates to an optical amplifier (TDFA) having a configuration which enables to reduce temperature dependence of the gain with reduced power consumption and simple control. The optical amplifier includes, in the order from an input port to an output port, an optical isolator, an optical coupler, an optical amplification fiber, an optical coupler, an optical isolator, an optical gain equalizing filter, a variable optical attenuator, an optical isolator, an optical coupler, an amplification fiber, an optical coupler, and an optical isolator. At least a core region of the optical amplification fiber is doped with Tm element, and signal light in a predetermined wavelength range is amplified by supply of pumping light. The gain equalizing fiber has a loss spectrum which shifts toward the short wavelength side as the temperature of the optical waveguide is higher, thereby equalizing the optical amplification gain of the signal light in the optical amplification fiber.

Abstract: The present invention relates to a pumping light source unit for Raman amplification and the like comprising a structure for improving the pumping light spectrum controllability so as to enable output signal light spectrum adjustment within an amplification wavelength band. The pumping light source unit comprises N (?2) pumping light sources for outputting N channels of pumping light having respective wavelengths different from each other, a multiplexer for multiplexing the N channels of pumping light, and an output structure for supplying a Raman amplification optical fiber with the pumping light outputted from the multiplexer. In particular, at least one of the N pumping light sources includes a variable length pumping light source adapted to change the channel wavelength of pumping light outputted therefrom. This configuration makes it possible to adjust pumping light spectra, thereby improving the controllability of output signal light spectra (Raman gain spectra).

Abstract: The invention relates to an amplification optical fiber that is suitable for amplification of signals in the L-band, that has the effect of suppressing normal four-wave mixing (FWM) occurring between signals, and that has the structure for effectively suppressing occurrence of non-degenerative FWM as well, and a fiber optic amplifier including the same. A fiber optic amplifier according to the present invention incorporates an amplification optical fiber having a core region doped with a rare earth element, a zero-dispersion wavelength of not more than a wavelength of pumping light, and an effective cutoff wavelength of 1.1 ?m or more but not more than the wavelength of the pumping light. Not only the normal FWM but also the non-degenerative FWM is effectively suppressed by application of the amplification optical fiber.

Abstract: A broad-band light source has a reduced tendency to oscillate and has high efficiency. The broad-band light source comprises (a) an optical waveguide that comprises a optical active element to generate an ASE lightwave when a pumping lightwave is supplied, that outputs an ASE lightwave in a first wavelength band from its first end, and that outputs an ASE lightwave in a second wavelength band from its second end, (b) a pumping lightwave-supplying means for supplying a pumping lightwave to the optical active element, and (c) a lightwave-combining means that receives the ASE lightwave in the first wavelength band, that receives the ASE lightwave in the second wavelength band, that combines the received ASE lightwaves, and that outputs the resultant ASE lightwave.

Abstract: The present invention relates to a fluorescent glass capable of being doped with a high concentration of rare earth ions and suitable for optical communication application, and an optical component incorporating it. The fluorescent glass comprises Al2O3 of 15 to 50 mol %; SiO2 of 0 to 80 mol %; an oxide of 5 to 85 mol % in total comprising at least one of B2O3, Ga2O3, Y2O3, Ta2O5, Sb2O3, Nd2O5, La2O3, and Yb2O3; and a rare earth ion. Concentration quenching is more suppressed in this fluorescent glass than in conventional fluorescent glasses, and it is thus feasible for the fluorescent glass to be doped with a high concentration of rare earth ions and to highly efficiently generate fluorescence of wavelengths in the signal wavelength bands generally used in optical communication.

Abstract: The present invention relates to an optical amplifier (TDFA) having a configuration which enables to reduce temperature dependence of the gain with reduced power consumption and simple control. The optical amplifier includes, in the order from an input port to an output port, an optical isolator, an optical coupler, an optical amplification fiber, an optical coupler, an optical isolator, an optical gain equalizing filter, a variable optical attenuator, an optical isolator, an optical coupler, an amplification fiber, an optical coupler, and an optical isolator. At least a core region of the optical amplification fiber is doped with Tm element, and signal light in a predetermined wavelength range is amplified by supply of pumping light. The gain equalizing fiber has a loss spectrum which shifts toward the short wavelength side as the temperature of the optical waveguide is higher, thereby equalizing the optical amplification gain of the signal light in the optical amplification fiber.