Abstract: The invention relates to a fiber laser device 100. In the preliminary pumping state, the laser light is not output from the seed laser light source 10, the pumping light is output from the pumping light source 10, and the pumping light has such an intensity that the wavelength of the laser light emitted and output from the amplification optical fiber 30 is not converted by the wavelength converter 71. In the output state, the laser light is output from the seed laser light source 10, the pumping light is output from the pumping light source 20, and the laser light and the pumping light have such intensities that the wavelength of the laser light amplified and output by the amplification optical fiber 30 is converted by the wavelength converter 71.

Abstract: When an output instruction is input to the control unit, the control unit controls the seed laser light source and the pumping light source to be either in a pre-pumped state or in an output state. In the pre-pumped state, laser light is not output from the seed laser light source, and pumping light with a predetermined intensity based on a laser light intensity set by the output setting unit is output from the pumping light source for a certain period of time. In the output state, laser light is output from the seed laser light source, and pumping light is output from the pumping light source, so that laser light with the intensity set by the output setting unit is output.

Abstract: The invention relates to a fiber laser device 100. In the preliminary pumping state, the laser light is not output from the seed laser light source 10, the pumping light is output from the pumping light source 10, and the pumping light has such an intensity that the wavelength of the laser light emitted and output from the amplification optical fiber 30 is not converted by the wavelength converter 71. In the output state, the laser light is output from the seed laser light source 10, the pumping light is output from the pumping light source 20, and the laser light and the pumping light have such intensities that the wavelength of the laser light amplified and output by the amplification optical fiber 30 is converted by the wavelength converter 71.

Abstract: A pulsed light generator of the invention includes: an excitation light source; a fiber grating into which excitation light from the excitation light source enters; a rare-earth doped optical fiber optically coupled with the fiber grating, in which a rare-earth element is doped into a core, serving as an optical transmitting section; an optical switch including a deflection element for causing a Q-switching operation; a first optical fiber that causes light from the rare-earth doped optical fiber to enter into the optical switch; and a second optical fiber for waveguiding pulsed light output from the optical switch. One surface side of the optical switch, into which light enters, is subjected to anti-reflection treatment with a reflectance with respect to a wavelength of the pulsed light output from the optical switch being 0.1% or less.

Abstract: A multi-core fiber for an optical pumping device is provided. The multi-core fiber includes a plurality of optical fibers that are inserted into holes of an alignment member. The optical fibers and the alignment member are integrated by heating. The alignment member includes a material that has a lower softening temperature than a softening temperature of the optical fibers.

Abstract: A MO-PA type optical amplifier is provided which includes an oscillator and an amplifier including a fiber for optical amplification, including: a reflected-light wavelength conversion fiber which is provided on an optical path between the oscillator and the amplifier and which converts a wavelength of reflected-light traveling toward the oscillator due to Stimulated Raman Scattering; and a filter which is provided on the optical path between the oscillator and the amplifier and which eliminates the wavelength-converted light.

Abstract: A pulsed light generator of the invention includes: an excitation light source; a fiber grating into which excitation light from the excitation light source enters; a rare-earth doped optical fiber optically coupled with the fiber grating, in which a rare-earth element is doped into a core, serving as an optical transmitting section; an optical switch including a deflection element for causing a Q-switching operation; a first optical fiber that causes light from the rare-earth doped optical fiber to enter into the optical switch; and a second optical fiber for waveguiding pulsed light output from the optical switch. One surface side of the optical switch, into which light enters, is subjected to anti-reflection treatment with a reflectance with respect to a wavelength of the pulsed light output from the optical switch being 0.1% or less.

Abstract: A rare earth-doped core optical fiber of the present invention includes a core comprising a silica glass containing at least aluminum and ytterbium, and a clad provided around the core and comprising a silica glass having a lower refraction index than that of the core, wherein the core has an aluminum concentration of 2% by mass or more, and ytterbium is doped into the core at such a concentration that the absorption band which appears around a wavelength of 976 nm in the absorption band by ytterbium contained in the core shows a peak absorption coefficient of 800 dB/m or less.

Abstract: [Object] An object of the invention is to provide a laser device having high optical amplification efficiency. [Solving Means] A laser device 100 includes: an optical fiber 20 which includes a core 21 and a clad 22 and through which seed light and pumping light propagate; and a glass rod 50 which is doped with rare earth elements, has a diameter larger than that of the core 21, wherein the seed light and the pumping light output from the optical fiber 20 are input to the glass rod 50 to have increased diameters, and output light including at least the amplified seed light is output from the glass rod 50.

Abstract: [Object] An optical amplifier and a resonator capable of outputting output light having a high intensity are provided.

Abstract: A multi-core fiber for an optical pumping device is provided. The multi-core fiber includes a plurality of optical fibers that are inserted into holes of an alignment member. The optical fibers and the alignment member are integrated by heating. The alignment member includes a material that has a lower softening temperature than a softening temperature of the optical fibers.

Abstract: A MO-PA type optical amplifier is provided which includes an oscillator and an amplifier including a fiber for optical amplification, including: a reflected-light wavelength conversion fiber which is provided on an optical path between the oscillator and the amplifier and which converts a wavelength of reflected-light traveling toward the oscillator due to Stimulated Raman Scattering; and a filter which is provided on the optical path between the oscillator and the amplifier and which eliminates the wavelength-converted light.

Abstract: A multi-mode optical coupler which includes an integrated section in which two optical fibers are fused and integrated together, at least one of these optical fibers being a multi-mode fiber, the multi-mode optical coupler coupling multi-mode light carried in the one of the multi-mode fibers to the other of the optical fibers, wherein: assuming that an outline of the integrated section in a plane view of the optical coupler is a function of a position along the longitudinal direction of the fibers, the multi-mode optical coupler has a plurality of inflection points along the outline; the multi-mode optical coupler satisfies: in an area between the farthermost inflection points includes: the length of the area between the inflection points is not more than 2 mm and an outer diameter h2 of the optical fibers along the direction in which the optical fibers are arranged in parallel is in the range of 70% to 80% of a sum of the outer diameters of the optical fibers; or the length of the area between the inflection

Abstract: A rare earth-doped core optical fiber includes a core comprising a silica glass containing at least aluminum and ytterbium, a clad provided around the core and comprising a silica glass having a lower refraction index than that of the core, and a polymer layer provided on the outer circumference of the clad and having a lower refractive index than that of the clad, wherein aluminum and ytterbium are doped into the core such that a loss increase by photodarkening, TPD, satisfies the following inequality (A). By this rare earth-doped core optical fiber, it is possible to manufacture an optical fiber laser capable of maintaining a sufficient laser oscillation output even when used for a long period of time. TPD?10{?0.655*(DAl)?4.304*exp{?0.00343*(AYb)}+1.

Abstract: A method of controlling a pulse output in a master oscillator-power amplifier type fiber pulse laser apparatus including a master oscillator unit and a power amplifier unit connected to the master oscillator unit is provided. The method includes starting the master oscillator unit before starting the power amplifier unit.

Abstract: A rare earth-doped core optical fiber of the present invention includes a core comprising a silica glass containing at least aluminum and ytterbium, and a clad provided around the core and comprising a silica glass having a lower refraction index than that of the core, wherein the core has an aluminum concentration of 2% by mass or more, and ytterbium is doped into the core at such a concentration that the light absorption band which appears around a wavelength of 976 nm in the light absorption band by ytterbium contained in the core shows a peak light absorption rate of 800 dB/m or less.

Abstract: This fiber laser is provided with: a signal light source that outputs a signal light; a rare earth-doped fiber that amplifies and outputs the signal light from the signal light source; a Raman amplifying fiber that is routed as a portion of an optical transmission path in order to output the output light from the rare earth-doped fiber to an outside thereof; and a wavelength selecting element that is provided in the optical transmission path from the Raman amplifying fiber to the signal light source and does not allow transmission of a Stokes light that is generated in the Raman amplifying fiber.

Abstract: A multi-mode optical coupler which includes an integrated section in which two optical fibers are fused and integrated together, at least one of these optical fibers being a multi-mode fiber, the multi-mode optical coupler coupling multi-mode light carried in the one of the multi-mode fibers to the other of the optical fibers, wherein: assuming that an outline of the integrated section in a plane view of the optical coupler is a function of a position along the longitudinal direction of the fibers, the multi-mode optical coupler has a plurality of inflection points along the outline; the multi-mode optical coupler satisfies: in an area between the farthermost inflection points includes: the length of the area between the inflection points is not more than 2 mm and an outer diameter h2 of the optical fibers along the direction in which the optical fibers are arranged in parallel is in the range of 70% to 80% of a sum of the outer diameters of the optical fibers; or the length of the area between the inflection

Abstract: A multi-port coupler for coupling an pumping light source to a cladding pump fiber for optical amplification, includes a central signal fiber and a plurality of pumping fibers arranged around the central signal fiber, the central signal fiber and the plurality of pumping fibers being unified and a front side is reduced in diameter, wherein an emitted light confining waveguide part is provided around a core of the signal fiber located at the center, and the emitted light confining waveguide part whose outer diameter is larger than that of the core has a higher refractive index than a cladding and a lower refractive index than the core and the emitted light confining waveguide part is formed continuously from a splicing point of the cladding pump fiber to a coupler front end branched into multiple fibers.

Abstract: A method of controlling a pulse output in a master oscillator-power amplifier type fiber pulse laser apparatus comprising a master oscillator unit and a power amplifier unit connected to the master oscillator unit, includes starting the master oscillator unit before starting the power amplifier unit.