Fujikura Limited

Other

Fujikara Ltd.

Michihiro Nakai

Tetsuya Sakai

Yasuhiro Oba

Satoshi Okude

Kensuke Shima

Kuniharu Himeno

Ryozo Yamauchi

Tomoharu Kitabayashi

Akira Wada

Hiroshi Hidaka

Yoshikiyo Noguchi

Masaaki Sudoh

Shoji Tanigawa

Naritoshi Yamada

Kenji Nishide

Masashi Ikeda

Yuu Ishii

Takuya Ienaka

In a case where the period from the input of the output suspension instruction to the next output instruction is shorter than the fixed period of time, the seed laser light source and the pumping light source are in a pre-pumped state during the period from the end of the output state to the start of the next output state. In a case where the period from the input of the output suspension instruction to the next output instruction is longer than the fixed period of time, the seed laser light source and the pumping light source are in the pre-pumped state only for the fixed period of time from the input of the output instruction.

Fiber laser device

A high power pulsed light generation device includes: a master clock generator that generates a master signal; an optical oscillator that generates a pulsed light synchronized with the master clock signal; an optical amplifier that amplifies the pulsed light emitted from the optical oscillator to output a high power pulsed light; a pump semiconductor laser that generates a pulsed light for pumping the optical amplifier; a driving unit that drives the pump semiconductor laser by a pulsed driving current synchronized with the master clock signal; and a control unit which controls the driving unit and controls a gain of the optical amplifier for each pulse by changing a pulse width of the pulsed drive current from driving unit so as to change the pulse width of the pumping pulsed light.

High power pulsed light generation device

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

Laser device

A high-power pulse light generator includes: a master oscillator generating oscillated pulse light in synchronization with a master clock signal; an optical amplifier amplifying the oscillated pulse light output from the master oscillator and outputting high-power pulsed light; a driving unit driving a pumping semiconductor laser in synchronization with the master clock signal; and a control unit controlling the driving unit so that the driving current to be supplied to the pumping semiconductor laser becomes lower than or equal to a set value at which the pumping semiconductor laser is not in a laser oscillation state when returning light from an irradiated body with the high-power pulsed light reaches the pumping semiconductor laser connected to the optical amplifier, the control unit determining a timing of the control in accordance with an optical path length between the irradiated body and the pumping semiconductor laser.

High-power pulsed light generator

A fiber laser includes a light emitting unit that amplifies pulsed signal light in a rare-earth doped fiber and emits output light, and a filter arranged in an optical path of the output light emitted from the light emitting unit. The signal light is light having a longer wavelength than a wavelength with which a gain is maximized in a rare-earth doped fiber within a gain wavelength band of the rare-earth doped fiber. The filter does not allow transmission of light in at least a part of the wavelength band that includes the wavelength with which the gain is maximized in the rare-earth doped fiber, and allows transmission of light having the same wavelength as the signal light and light in a wavelength band on a longer wavelength side than the wavelength of the signal light.

Fiber laser

An optical amplifier includes: a first optical fiber, through which seed light and excitation light propagate; an optical coupler that inputs the excitation light into the first optical fiber; a first lens to which the seed light and the excitation light output from the first optical fiber are input and which increases diameters of the seed light and the excitation light; a glass rod doped with rare earth elements to be excited by the excitation light, to which the seed light and the excitation light output from the first lens are input and which amplifies and outputs the seed light as output light; a second lens to which at least the output light output from the glass rod is input and which decreases a diameter of the output light; and a second optical fiber to which the output light output from the second lens is input.

Optical amplifier and resonator

When an output instruction is input to a control unit, the control unit controls a seed laser light source and a pumping light source to be either in a pre-pumped state or in an output state. In the pre-pumped state, the pumping light source outputs, for a predetermined period, pumping light with an intensity determined based on the duration of the period of time from when the output state prior to the input of the output instruction to the control unit comes to an end till when the output instruction is input to the control unit. In the output state, to cause the output unit to output laser light, the seed laser light source outputs laser light, and the pumping light source outputs pumping light.

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.

The laser device includes: a seed light source that outputs seed light; a pumping light source an amplification optical fiber as the amplifier that amplifies the seed light with an element pumped by the pumping light source; a monitor unit that is provided between the seed light source and the amplification optical fiber, and monitors the intensity of the light output from the amplification optical fiber; and a light source controller that controls the seed light source. In this laser device, when the light input to the monitor unit has an intensity equal to or higher than a predetermined intensity while the seed light is not input to the amplification optical fiber, the light source controller forces to output the seed light from the seed light source.

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.

[Object] An object of the invention is to provide a laser device having high optical amplification efficiency. [Solving Means] A laser deviceincludes: an optical fiberwhich includes a coreand a cladand through which seed light and pumping light propagate; and a glass rodwhich is doped with rare earth elements, has a diameter larger than that of the core, wherein the seed light and the pumping light output from the optical fiberare input to the glass rodto have increased diameters, and output light including at least the amplified seed light is output from the glass rod

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.

Rare earth-doped core optical fiber and manufacturing method thereof

The invention relates to a fiber laser device. In the preliminary pumping state, the laser light is not output from the seed laser light source, the pumping light is output from the pumping light source, and the pumping light has such an intensity that the wavelength of the laser light emitted and output from the amplification optical fiberis not converted by the wavelength converter. In the output state, the laser light is output from the seed laser light source, the pumping light is output from the pumping light source, 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 fiberis converted by the wavelength converter

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. A low-reflection section having a reflectance with respect to the wavelength of the pulsed light output from the optical switch of from 1% to 60% inclusive, is arranged on an other surface side of the optical switch, from which light is emitted.

Growing community of inventors

Sakura, Japan

Michihiro Nakai