JP6477209B2 - Combined laser light source and fiber adjustment method - Google Patents

Description

  The present invention relates to a combined laser light source and a fiber adjustment method that combine laser beams from a plurality of independent light sources to increase brightness.

  Conventionally, as a method for increasing the output of a laser, a method of combining a plurality of laser beams from a plurality of light sources into a single optical fiber (Patent Document 1) or a bundle of fibers combined with a plurality of light sources is bundled. There is a known method of coupling to a single fiber.

JP 2002-202442 A

  However, when combining a single optical fiber having a value equal to or several times the product of the emitter size and beam divergence angle of a plurality of independent package type semiconductor lasers, It was not easy to efficiently couple to a fiber having a core size that is difficult to align. In such a case, since a plurality of laser beams are incident on the clad and the clad mode light propagates in the clad, it is necessary to absorb the clad mode light.

  It is an object of the present invention to provide a combined laser light source and a fiber adjustment method that can easily couple a plurality of laser beams to a fiber having a core size that is difficult to align and can absorb clad mode light. .

In order to solve the above problems, a combined laser light source according to the present invention includes a plurality of laser light sources each outputting laser light, a core, and a clad, and clad mode light is provided on the incident side of the laser light. A fiber having a mode stripper mechanism that removes light, a coupling lens that couples the laser light from the plurality of laser light sources to the fiber, an output monitor that monitors the output of the fiber, and the incidence of the fiber A ferrule that is attached to the side and absorbs the clad mode light, a temperature monitor that monitors the temperature of the ferrule, and a movement control signal that maximizes the output of the output monitor and minimizes the temperature of the temperature monitor. Bei example a control unit for outputting, and a moving mechanism for moving the ferrule on the basis of the movement control signal from the control unit, Serial control unit, when said monitored temperature monitor temperature exceeds a predetermined value, characterized in that stops the plurality of laser light sources.

According to the present invention, using a fiber having a mode stripper mechanism that removes the cladding mode light on the laser beam incident side, the laser light output is monitored by the output monitor, and when the ferrule absorbs the cladding mode light, the temperature monitor The temperature rise of the ferrule is monitored, the control unit outputs a movement control signal for maximizing the output of the output monitor and minimizing the temperature of the temperature monitor, and the movement mechanism moves the ferrule based on the movement control signal from the control unit. Since they are moved, a plurality of laser beams can be easily coupled to a fiber having a core size that is difficult to align. Furthermore, it absorbs cladding mode light and unnecessary light that has not been coupled to the core and prevents reflection, so that damage due to unnecessary light can be suppressed, and the ferrule functions as a radiator. The control unit can stop the plurality of laser light sources when the temperature monitored by the temperature monitor exceeds a predetermined value.

It is a figure which shows the structure of the combining laser light source of Example 1 of this invention. It is a figure which shows the window attached to the front-end | tip of the optical fiber of the combining laser light source of Example 1 of this invention.

  Embodiments of a combined laser light source and a fiber adjustment method of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of a combined laser light source according to the first embodiment. 1 includes a semiconductor laser 1a to 1e, lenses 2a to 2e, a coupling lens 3, an optical fiber 4, a copper ferrule 5, a temperature monitor 7, an output monitor 8, a control unit 9, and movement. A mechanism 10 is provided. Here, each element number is assigned as a subscript, and a to e do not mean 5 but may be other than 5.

  The semiconductor lasers 1a to 1e are arranged at predetermined intervals, and are excited by carrier injection composed of electrons and holes injected by current drive, and are induced emission generated when the injected electron and hole carrier pairs are annihilated. The laser beam generated by is output. The semiconductor laser may be an array laser having a plurality of laser emission mechanisms in a bar-shaped semiconductor, or a laser having a planar light emission distribution such as a surface emitting laser or a stack laser in which bar-shaped array lasers are stacked.

  As the semiconductor lasers 1a to 1e, semiconductor lasers that output laser light having a predetermined wavelength of 600 nm or less are used.

  The lenses 2 a to 2 e are arranged at predetermined intervals so as to face the semiconductor lasers 1 a to 1 e, and guide the laser beams from the semiconductor lasers 1 a to 1 e to the coupling lens 3. When the beam divergence angle is large as in the case of a semiconductor laser, it is preferable to use a collimated arrangement capable of obtaining a certain amount of parallel light. In the case of a laser having a small divergence angle, the lenses 2a to 2c are not necessarily required.

  The coupling lens 3 serves as a condensing lens and condenses a plurality of laser beams from the semiconductor lasers 1a to 1e into the optical fiber 4 by condensing them.

  The optical fiber 4 includes a core 4a having a core size that is difficult to align, for example, 100 um or less, and a clad 4b disposed outside the core 4a, and a plurality of laser beams from the coupling lens 3 are clad with the core 4a. Then, the laser beam in the core 4 a is transmitted to the output end of the optical fiber 4.

  The optical fiber 4 has a mode stripper mechanism (also referred to as a clad mode stripper) that removes the clad mode light on the laser light incident side. That is, the mode stripper mechanism has a layer of a high refractive index material arranged in contact with the clad of the optical fiber 4 and optically coupled, and outputs clad mode light propagating in the clad 4b to the outside of the clad 4b. Has the function of

  The copper ferrule 5 is attached to the incident side of the optical fiber 4 via a gap 6, and absorbs the clad mode light from the clad 4 b via the gap 6. Since the copper ferrule 5 absorbs laser light having a wavelength of 600 nm or less, the temperature rise of the copper ferrule 5 is large. In place of the copper ferrule 5, a ferrule such as gold or silver having a high absorption rate may be used.

  The temperature monitor 7 has a temperature sensor, for example, and detects and monitors the temperature of the copper ferrule 5. The output monitor 8 is a photodiode or the like and is disposed at a position facing the emission end of the optical fiber 8 and monitors the laser light output from the optical fiber 8.

  The control unit 9 outputs a movement control signal to the moving mechanism 10 so that the output of the output monitor 8 is maximized and the temperature of the temperature monitor 7 is minimized. The moving mechanism 10 moves the copper ferrule 5 in a three-dimensional direction (X direction, Y direction, Z direction orthogonal to each other) based on a movement control signal from the control unit 9.

  Next, the operation of the combined laser light source of the embodiment configured as described above will be described. First, a plurality of laser beams from the semiconductor lasers 1 a to 1 e are guided to the coupling lens 3 through the lenses 2 a to 2 e, collected by the coupling lens 3, and combined with the optical fiber 4.

  An optical fiber 4 having a mode stripper mechanism that removes the cladding mode light is used on the laser beam incident side of the optical fiber 4. The cladding mode light incident on the cladding 4 b passes through the gap 6 and passes through the copper ferrule 5. Absorbed. For this reason, the temperature of the copper ferrule 5 rises.

  The temperature monitor 7 monitors the temperature rise of the copper ferrule 5, and the output monitor 8 monitors the laser beam output. The control unit 9 outputs a movement control signal to the moving mechanism 10 so that the output of the output monitor 8 is maximized and the temperature of the temperature monitor 7 is minimized.

  The moving mechanism 10 adjusts the position of the optical fiber 4 by moving the copper ferrule 5 in a three-dimensional direction (X direction, Y direction, Z direction orthogonal to each other) based on a movement control signal from the control unit 9. For this reason, the output of the output monitor 8 is maximized and the temperature of the temperature monitor 7 is minimized. That is, a plurality of laser beams can be easily coupled to a fiber having a core size that is difficult to align.

  Furthermore, the cladding mode light and unnecessary light that has not been coupled to the core are absorbed, and reflection is prevented so that damage due to unnecessary light can be suppressed. Moreover, the copper ferrule 5 can function as a heat radiator.

  Further, when the power density of the laser light becomes higher than a predetermined level, a window 11 is attached to the end face of the optical fiber 4 as shown in FIG. May be.

  Note that the controller 9 may stop the semiconductor lasers 1a to 1e when the temperature monitored by the temperature monitor 7 exceeds a predetermined value, that is, when the temperature becomes abnormal.

  Here, the case of a semiconductor laser as an example of the laser light source has been described. However, a laser light source in which a plurality of ordinary laser devices are installed or a laser beam that bundles a plurality of fibers is shown. Such a laser light source can also be implemented.

  The combined laser light source according to the present invention is particularly applicable to laser processing apparatus, laser illumination, laser exposure apparatus, fluorescent material excitation, laser measurement, laser medical treatment, and the like.

1a to 1e Semiconductor lasers 2a to 2e Lens 3 Coupling lens 4 Optical fiber 4a Core 4b Clad 5 Copper ferrule 6 Gap 7 Temperature monitor 8 Output monitor 9 Control unit 10 Moving mechanism

Claims (4)

A plurality of laser light sources each outputting laser light;
A fiber having a core and a clad, and having a mode stripper mechanism for removing clad mode light on the laser beam incident side;
A coupling lens coupled to the fiber by condensing laser light from the plurality of laser light sources;
An output monitor for monitoring the output of the fiber;
A ferrule attached to the incident side of the fiber for absorbing the cladding mode light and unwanted light not coupled to the core ;
A temperature monitor for monitoring the temperature of the ferrule;
A control unit for outputting a movement control signal for maximizing the output of the output monitor and minimizing the temperature of the temperature monitor;
A moving mechanism for moving the ferrule based on a movement control signal from the control unit;
With
The combined laser light source, wherein the controller stops the plurality of laser light sources when a temperature monitored by the temperature monitor exceeds a predetermined value. The plurality of laser light sources each output laser light having a predetermined wavelength or less,
2. The combined laser light source according to claim 1, wherein the ferrule is made of a copper ferrule having high absorption at the predetermined wavelength.   3. The combined laser light source according to claim 1, wherein a window for adjusting the power density of the laser light is attached to the end face of the fiber. A fiber having a mode stripper mechanism for removing clad mode light on the laser light incident side having a core and a clad,
By coupling the laser light from a plurality of laser light sources using a coupling lens to couple to the fiber,
Monitor the output of the fiber with an output monitor,
With a ferrule attached to the incident side of the fiber, the cladding mode light and unnecessary light that has not been coupled to the core are absorbed,
Monitor the temperature of the ferrule with a temperature monitor;
A movement control signal for maximizing the output of the output monitor and minimizing the temperature of the temperature monitor is output from the control unit,
Adjust the position of the fiber by moving the ferrule with a moving mechanism based on a movement control signal from the control unit,
Coupling the plurality of laser beams into the fiber;
The control unit stops the plurality of laser light sources when the temperature monitored by the temperature monitor exceeds a predetermined value.

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