JP2006147879A - Semiconductor laser device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser device which is hardly affected by return light. <P>SOLUTION: Laser light L1 emitted from a semiconductor laser 2 is shaped into a horizontally long beam of light by narrowing a vertical radiant angle via a cylindrical lens 3a, and then transformed into parallel light via a nonspherical lens 3b. The laser light L1 transformed into the parallel light via the nonspherical lens 3b falls slantly to the incident end face 4a of an optical fiber 4 after passing through a nonspherical lens 3c. Part of light falling to the incident end face 4a of the optical fiber 4 is reflected on the end face 4a to become return light L2. The slant incidence of the laser light L1 on the incident end face 4a causes the return light L2 to proceed along a light path separated from that of the laser light L1 and falls to the nonspherical lens 3c, which transforms the return light L2 into the parallel light. A filter 5A is arranged in the light path for the return light L2, and cuts off the return light L2 without cutting off the laser light L1 by means of the filter 5A. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor laser device that guides laser light emitted from a semiconductor laser through an optical fiber and uses it for various processing. More specifically, the failure of the semiconductor laser is prevented by preventing the return light of the laser light emitted from the semiconductor laser from entering the semiconductor laser.

  2. Description of the Related Art Conventionally, a semiconductor laser device has been proposed in which laser light emitted from a semiconductor laser is coupled to an optical fiber, and the laser light from the semiconductor laser is guided through the optical fiber and used for various processes such as cutting.

  A semiconductor laser used in a semiconductor laser device has a form in which light is irradiated from a cleavage plane. Such a semiconductor laser has a horizontal radiation angle different from a vertical radiation angle, and has a vertically elongated elliptical emission pattern.

  On the other hand, the radiation angle of the optical fiber is symmetric. For this reason, an apparatus having a beam shape close to a perfect circle has been proposed for the purpose of increasing the symmetry of light emitted from a semiconductor laser and increasing the coupling efficiency with an optical fiber (for example, Patent Documents). 1).

  Moreover, in a semiconductor laser device used for processing, a high-power semiconductor laser is used. A high-power semiconductor laser has a high power density at the output end face, and when light emitted by itself or light emitted by another device due to light emitted by itself returns to its output end face, The problem is that end face deterioration and end face destruction occur due to fluctuations in the oscillation spectrum and surface absorption.

  For this reason, an apparatus has been proposed in which the laser light from the semiconductor laser and the return light reflected by the incident end face of the optical fiber are optically separated, and the return light to the semiconductor laser is blocked by a shielding plate (for example, Patent Document 2). reference).

JP-A-8-307006 JP-A-5-323404

  However, when the coupling efficiency between the semiconductor laser and the optical fiber increases, the return light of the semiconductor laser reflected by the incident end face of the optical fiber irradiates the output end face of the semiconductor laser or enters the optical fiber. The reflected light is reflected from the exit end face side of the optical fiber, etc., and is returned from the entrance end face to irradiate the output end face of the semiconductor laser. As a result, there are problems in that the oscillation spectrum of the semiconductor laser, end face deterioration due to surface absorption, and end face destruction occur.

  In addition, in order to increase the coupling efficiency between the semiconductor laser and the optical fiber, the beam shape is a shape close to a perfect circle and the return light is separated by an optical path and blocked by a shielding plate. If the amount of deviation of the optical path of the return light is not increased, only the return light cannot be blocked, resulting in a problem that the apparatus becomes large.

  The present invention has been made to solve the above-described problems, and has an object to provide a small-sized semiconductor laser device that can reduce fluctuations in the oscillation spectrum, surface degradation, and end face destruction of a semiconductor laser, and can be reduced in size. To do.

  In order to solve the above-described problems, a semiconductor laser device according to the present invention shapes a light source that emits laser light, a light guide that guides laser light, and laser light emitted from the light source, and collects the light guide. An optical element that emits light, and a filter that transmits laser light emitted from the light source and shaped by the optical element and blocks return light generated by the light guide.

  In the semiconductor laser device of the present invention, the laser light emitted from the light source is shaped by the optical element, passes through the filter, and is condensed on the light guide. Most of the laser light focused on the light guide is guided through the light guide. On the other hand, a part of the laser beam condensed on the light guide is reflected by the end face of the light guide to become return light. Return light returning from the light guide to the light source is blocked by the filter and does not enter the light source.

  For example, by narrowing the vertical radiation angle of the laser light emitted from the light source and shaping it into a horizontally long beam shape, obliquely entering the incident end face of the light guide and separating the optical path from the return light, a semiconductor laser Only the return light can be blocked by the filter without increasing the amount of deviation between the optical paths of the laser beam and the return light.

  Further, the laser beam emitted from the light source is narrowed in the vertical direction and shaped into a horizontally long beam shape, and the light guide is guided to be smaller than the beam shape of the return light emitted from the incident end face. Thus, the return light guided through the light guide can be blocked.

  Furthermore, by providing a wavelength selection filter through which the laser light having a wavelength emitted from the light source passes, it is possible to block the return light having different wavelengths guided through the light guide.

  According to the semiconductor laser device of the present invention, the laser light emitted from the light source is shaped so that it can be separated from the return light at the end face of the light guide, the laser light emitted from the light source is transmitted, and the return light is Since the blocking filter is arranged, it is possible to prevent the return light from entering the light source without increasing the size of the apparatus, and to reduce the fluctuation of the oscillation spectrum of the light source, the surface deterioration, and the occurrence of end face destruction.

  Hereinafter, embodiments of a semiconductor laser device of the present invention will be described with reference to the drawings.

<Configuration Example of Semiconductor Laser Device in First Embodiment>
FIG. 1 is a configuration diagram showing an example of a semiconductor laser device 1A according to the first embodiment. FIG. 1 schematically shows a configuration of a semiconductor laser device 1A. FIG. 1A is a YZ plan view, FIG. 1B is an XZ plan view, and FIG. is there.

  The semiconductor laser device 1A according to the first embodiment is an apparatus used for various types of processing, and includes a semiconductor laser 2, a cylindrical lens 3a, aspherical lenses 3b and 3c, an optical fiber 4, and a filter 5A. In the semiconductor laser device 1A, a semiconductor laser 2, a cylindrical lens 3a, aspherical lenses 3b and 3c, a filter 5A, and the like are mounted in a package (not shown). Light is guided to the optical fiber 4 by the spherical lenses 3b and 3c, and the light is guided by the optical fiber 4 to be used for cutting or the like.

  The laser beam L1 irradiated from the semiconductor laser 2 and guided to the optical fiber 4 by the cylindrical lens 3a and the aspherical lenses 3b and 3c and the return light L2 reflected by the incident end face 4a of the optical fiber 4 are optically separated, and A filter 5A that transmits the laser light L1 of the semiconductor laser 2 and blocks the return light L2 is disposed to prevent the return light L2 from entering the semiconductor laser 2.

  The semiconductor laser 2 is an example of a light source and is mounted on a substrate or the like. The laser light L1 emitted from the semiconductor laser 2 has different beam divergence angles in the direction along the XZ plane horizontal to the active layer (not shown) and in the direction along the vertical YZ plane. The radiation angle of the semiconductor laser 2 is represented by the full width at half maximum of the optical output, the full width at half maximum θh in the horizontal direction is about 8 degrees, and the full width at half maximum θv in the vertical direction is about 25 degrees. Thereby, the emission pattern of the laser beam L1 emitted from the semiconductor laser 2 has a vertically long and substantially elliptical shape.

  The optical fiber 4 is an example of a light guide. In this example, a multimode optical fiber is used, for example. The allowable incident angle in the optical fiber 4 is limited by the NA (numerical aperture) of the optical fiber 4. In order to make the laser light L 1 of the semiconductor laser 2 incident on the optical fiber 4, the radiation angle of the semiconductor laser 2 is changed to the optical fiber. It is necessary to perform beam shaping to an allowable incident angle of 4 or less.

  For this reason, the semiconductor laser device 1A shown in FIG. 1 includes a cylindrical lens 3a, an aspherical lens 3b, and an aspherical lens 3c as optical elements that shape the beam of the semiconductor laser 2 and guide it to the optical fiber 4.

  The cylindrical lens 3a forms a first lens, and converts the radiation angle in the vertical direction of the laser light L1 emitted from the semiconductor laser 2 to about 1/10. Note that the radiation angle in the horizontal direction does not change in the cylindrical lens 3a. As a result, the beam shape of the laser light L1 emitted from the semiconductor laser 2 becomes a horizontally long, substantially elliptical shape when transmitted through the cylindrical lens 3a.

  The aspherical lens 3b and the aspherical lens 3c constitute a second lens. The aspherical lens 3b converts the laser light L1 transmitted through the cylindrical lens 3a into parallel light, and is incident on the optical fiber 4 by the aspherical lens 3c. Condensed on the end face 4a.

  Here, the incident end face 4a of the optical fiber 4 is provided with a non-reflective coating, but a part of the laser light L1 irradiated from the semiconductor laser 2 and condensed on the incident end face 4a of the optical fiber 4 is: Reflected by the incident end face 4a. The return light L2 reflected by the incident end face 4a of the optical fiber 4 is converted into parallel light by the aspheric lens 3c. Note that the beam shape of the return light L2 is also a horizontally long substantially elliptical shape because the beam shape of the laser light L1 is a horizontally long substantially elliptical shape.

  In the semiconductor laser device 1A shown in FIG. 1, a cylindrical lens 3a and an aspherical lens 3b are disposed on the optical axis P1 of the semiconductor laser 2 along the Z axis. The aspherical lens 3c and the optical fiber 4 are arranged such that the optical axis P2 is shifted in parallel to the optical axis P1 of the semiconductor laser 2 by a predetermined length (−y) along the Y axis to constitute an optical path separating unit. To do.

Thereby, the laser beam L1 irradiated from the semiconductor laser 2 and transmitted through the aspherical lens 3c is incident on the incident end face 4a of the optical fiber 4 at an angle θ ₂ as shown in FIG.

Here, the angle θ ₂ is an angle formed between the incident beam of the laser beam L 1 of the semiconductor laser 2 and the normal line of the incident end face 4 a of the optical fiber 4. The optical system is configured such that θ ₁ <θ _{2 where} θ ₁ is the spread angle (half angle) of the incident beam. Between the aspherical lens 3b and the aspherical lens 3c, the laser beam of the semiconductor laser 2 is formed. The optical path of the return light L2 reflected by the incident end face 4a of L1 and the optical fiber 4 is spatially separated.

  The filter 5A is disposed between the aspherical lens 3b and the aspherical lens 3c, transmits the laser light L1 emitted from the semiconductor laser 2, and blocks the return light L2 reflected by the incident end face 4a of the optical fiber 4. Is provided. As the filter 5A, for example, a plate-like member may be arranged in the optical path of the return light L2 between the aspheric lens 3b and the aspheric lens 3c. Further, a plate-like member having a slit-like opening through which the laser light L1 from the semiconductor laser 2 passes may be disposed.

  Here, between the aspherical lens 3b and the aspherical lens 3c, the beam shapes of the laser light L1 irradiated from the semiconductor laser 2 and the return light L2 reflected by the incident end face 4a of the optical fiber 4 are both substantially horizontally long. It is elliptical. For this reason, the laser beam L1 from the semiconductor laser 2 and the return light L2 reflected by the incident end face 4a are optically separated without increasing the amount of deviation from the optical axis of the aspheric lens 3c and the optical fiber 4.

<Operation Example of Semiconductor Laser Device in First Embodiment>
Next, an operation example of the semiconductor laser device 1A according to the first embodiment will be described with reference to FIG.

  The laser beam L1 emitted from the semiconductor laser 2 is converted into a horizontally elongated substantially elliptical beam shape by converting the radiation angle in the vertical direction to about 1/10 by the cylindrical lens 3a.

  Laser light L1 irradiated from the semiconductor laser 2 and transmitted through the cylindrical lens 3a is converted into parallel light by the aspherical lens 3b. The filter 5A disposed between the aspherical lens 3b and the aspherical lens 3c is shaped to transmit the laser beam L1 irradiated from the semiconductor laser 2 and transmitted through the cylindrical lens 3a and the aspherical lens 3b. Therefore, the laser beam L1 emitted from the semiconductor laser 2 passes through the filter 5A and enters the aspheric lens 3c.

As described above, the aspheric lens 3c and the optical fiber 4 are irradiated from the semiconductor laser 2 because the optical axis P2 is arranged parallel to the optical axis P1 of the semiconductor laser 2 along the Y axis. The laser beam L1 is condensed on the incident end face 4a of the optical fiber 4 by the aspheric lens 3c at an incident angle θ ₂ as shown in FIG.

  Most of the laser light L1 collected on the incident end face 4a of the optical fiber 4 is incident on a core (not shown) of the optical fiber 4 and guided there. On the other hand, a part of the laser beam L1 condensed on the incident end face 4a of the optical fiber 4 is reflected by the incident end face 4a.

Laser light L1 converged on the entrance end face 4a of the optical fiber 4, is incident at an incident angle theta _2, the return light L2 reflected by the incident end surface 4a is reflected at the same reflection angle as the incident angle theta _2. Since θ ₁ <θ ₂ with respect to the spread angle θ ₁ (half angle) of the incident beam to the optical fiber 4, the laser light L 1 of the semiconductor laser 2 is between the aspheric lens 3 b and the aspheric lens 3 c. The optical path of the return light L2 reflected by the incident end face 4a of the optical fiber 4 is spatially separated. Then, the return light L2 reflected by the incident end face 4a of the optical fiber 4 is blocked by the filter 5A, and is prevented from entering the semiconductor laser 2 again.

  Here, the optical axis P1 of the aspherical lens 3c and the optical fiber 4 is formed by shaping the beam shape of the laser light L1 emitted from the semiconductor laser 2 into a horizontally elongated substantially elliptical shape by the cylindrical lens 3a and the aspherical lens 3b. The laser beam L1 of the semiconductor laser 2 and the return beam L2 reflected by the incident end face 4a of the optical fiber 4 are spatially separated without increasing the deviation amount from the laser beam, and the laser beam L1 of the semiconductor laser 2 is blocked. The return light L2 can be blocked by the filter 5A.

  In the semiconductor laser device 1A of the first embodiment, the aspherical lens 3c and the optical fiber 4 are arranged so as to be shifted parallel to the optical axis P1, but for example, oblique polishing with the incident end face 4a inclined. If a fiber is used, optical path separation can be realized without shifting the aspherical lens 3c and the optical axis P2 of the optical fiber 4.

  According to such a configuration, the return light L2 reflected by the incident end face 4a of the optical fiber 4 can be prevented from entering the semiconductor laser 2 again, and the fluctuation of the oscillation spectrum and surface deterioration of the semiconductor laser 2 can be prevented. It is possible to provide the semiconductor laser device 1A in which occurrence of end face destruction is reduced.

<Configuration Example of Semiconductor Laser Device of Second Embodiment>
FIG. 2 is a block diagram showing an example of the semiconductor laser device 1B according to the second embodiment. Next, a second embodiment of the semiconductor laser device will be described. Here, FIG. 2 schematically shows the configuration of the semiconductor laser device 1B, and portions having the same configuration as the semiconductor laser device 1A described in FIG.

  In the semiconductor laser device 1B of the second embodiment, the laser light L1 emitted from the semiconductor laser 2 is transmitted, guided through the optical fiber 4 from the exit end face 4b side to the entrance end face 4a side, and from the entrance end face 4a. A part of the emitted return light L3 is provided with a filter 5B for blocking, so that the return light L3 emitted from the incident end face 4a of the optical fiber 4 is prevented from entering the semiconductor laser 2.

  In the semiconductor laser device 1B, the aspherical lens 3c and the optical fiber 4 are disposed on the optical axis P1 of the semiconductor laser 2 together with the cylindrical lens 3a and the aspherical lens 3b.

  In this example, the laser light L1 emitted from the semiconductor laser 2 is guided to the optical fiber 4 and condensed on the incident end face 4a by the optical element constituted by the cylindrical lens 3a and the aspherical lenses 3b and 3c. Is guided from the incident end face 4a side to the outgoing end face 4b side. A part of the light irradiated from the semiconductor laser 2 and guided through the optical fiber 4 becomes return light L3 guided from the exit end face 4b side of the optical fiber 4 to the entrance end face 4a side.

  The light guided through the optical fiber 4 from the exit end face 4b side to the entrance end face 4a side is irradiated from the semiconductor laser 2 and incident from the entrance end face 4a of the optical fiber 4 and guided through the optical fiber 4. There is return light reflected on the emission end face 4 b side of the fiber 4.

  Further, there is light coupled to the output end face 4 b of the optical fiber 4 by being reflected by another device such as an optical fiber amplifier (not shown) connected to the optical fiber 4.

The return light L3 emitted from the incident end face 4a of the optical fiber 4 is radiated from the incident end face 4a of the optical fiber 4 at a radiation angle θ ₃ (NA = sin (θ ₃ )) determined by the NA of the optical fiber 4. The return light L3 is converted into parallel light by the aspherical lens 3c and becomes a substantially circular pattern having a beam diameter of W2.

  The laser beam L1 emitted from the semiconductor laser 2 passes through the cylindrical lens 3a and the aspherical lens 3b, so that it becomes a horizontally long, substantially elliptical beam shape as described above. The laser beam L1 of the semiconductor laser 2 has a magnitude of W1 in the Y-axis direction. Here, the optical system is configured such that W1 <W2.

  The filter 5B is disposed between the aspherical lens 3b and the aspherical lens 3c, and an opening 6 having a size of W3 is formed in the Y-axis direction. Here, the size W3 of the opening 6 of the filter 5B in the Y-axis direction is configured to satisfy W1 <W3 <W2, as shown in FIG. The size of the opening 6 in the X-axis direction is set so that the laser beam L1 emitted from the semiconductor laser 2 can be transmitted.

  Thereby, the laser beam L1 emitted from the semiconductor laser 2 passes through the opening 6 of the filter 5B. On the other hand, the return light L3 emitted from the incident end face 4a of the optical fiber 4 is blocked by the filter 5B at the portion outside the opening 6 of the filter 5B.

<Operation Example of Semiconductor Laser Device of Second Embodiment>
Next, an operation example of the semiconductor laser device 1B of the second embodiment will be described with reference to FIG.

  The laser beam L1 emitted from the semiconductor laser 2 is converted into a horizontally elongated substantially elliptical beam shape by converting the radiation angle in the vertical direction to about 1/10 by the cylindrical lens 3a.

  Laser light L1 irradiated from the semiconductor laser 2 and transmitted through the cylindrical lens 3a is converted into parallel light by the aspherical lens 3b. The laser beam L1 irradiated from the semiconductor laser 2 and shaped through the cylindrical lens 3a and the aspheric lens 3b has a size of W1 in the Y-axis direction.

  The filter 5B disposed between the aspherical lens 3b and the aspherical lens 3c has an opening 6 having a size of W3 in the Y-axis direction. Therefore, the filter 5B is irradiated from the semiconductor laser 2 and transmitted through the aspherical lens 3b. The laser beam L1 passes through the opening 6 of the filter 5B and enters the aspheric lens 3c.

  Then, the laser light L 1 incident on the aspheric lens 3 c is condensed on the incident end face 4 a of the optical fiber 4 and enters the optical fiber 4. The light incident on the optical fiber 4 is guided from the incident end face 4a side to the outgoing end face 4b side. Part of the light guided from the incident end face 4a side to the outgoing end face 4b side of the optical fiber 4 is reflected by the outgoing end face 4b to become return light, and the optical fiber 4 is guided from the outgoing end face 4b side to the incident end face 4a side. Waved.

  Further, a part of the light emitted from the emission end face 4 b of the optical fiber 4 is reflected by another device such as an optical fiber amplifier (not shown) connected to the optical fiber 4 to be reflected on the emission end face 4 b of the optical fiber 4. Then, the optical fiber 4 is guided from the exit end face 4b side to the entrance end face 4a side.

  The return light L3 guided through the optical fiber 4 from the exit end face 4b side to the entrance end face 4a side exits from the entrance end face 4a. The return light L3 emitted from the incident end face 4a of the optical fiber 4 is converted into parallel light by the aspheric lens 3c. The beam shape of the return light L3 is a substantially circular shape having a beam diameter of W2.

  Since the size W3 of the opening 6 of the filter 5B in the Y-axis direction is configured to satisfy W1 <W3 <W2, the return light L3 emitted from the incident end face 4a of the optical fiber 4 is shown in FIG. As indicated by hatching in b), the portion outside the opening 6 of the filter 5B is blocked by the filter 5B.

  The return light L3 transmitted through the inside of the opening 6 of the filter 5B irradiates the semiconductor laser 2, but the amount of light is reduced as compared with the case where the filter 5B is not present.

  According to such a configuration, a part of the return light L3 that is guided from the exit end face 4b side of the optical fiber 4 to the entrance end face 4a side and exits from the entrance end face 4a can be blocked, and the semiconductor laser 2 oscillates. It is possible to provide the semiconductor laser device 1B in which the occurrence of spectrum fluctuation, surface degradation, and end face destruction is reduced.

<Configuration Example of Semiconductor Laser Device According to Third Embodiment>
FIG. 3 is a block diagram showing an example of a semiconductor laser device 1C according to the third embodiment. Next, a third embodiment of the semiconductor laser device will be described. Here, FIG. 3 schematically shows the configuration of the semiconductor laser device 1C, and portions having the same configuration as the semiconductor laser device 1A described in FIG.

  In the semiconductor laser device 1C of the third embodiment, the laser light L1 having the wavelength irradiated from the semiconductor laser 2 is transmitted, guided through the optical fiber 4 from the emission end face 4b side to the incident end face 4a side, and the incident end face A return light L4 having a wavelength different from that of the laser light L1 emitted from the semiconductor laser 2 emitted from 4a is provided with a filter 5C that blocks the return light L4 emitted from the incident end face 4a of the optical fiber 4 from entering the semiconductor laser 2. Is.

  In the semiconductor laser device 1 </ b> C, the aspherical lens 3 c and the optical fiber 4 are disposed on the optical axis P <b> 1 of the semiconductor laser 2 together with the cylindrical lens 3 a and the aspherical lens 3 b.

  As described above, a part of the laser light L1 emitted from the semiconductor laser 2 becomes return light that is guided from the exit end face 4b side of the optical fiber 4 to the entrance end face 4a side.

  Here, the light guided through the optical fiber 4 from the emission end face 4b side to the incident end face 4a side may be different from the wavelength of the laser light L1 irradiated by the semiconductor laser 2 of the semiconductor laser device 1C.

  For example, an optical fiber amplifier (not shown) having a grating mirror is connected to the optical fiber 4 of the semiconductor laser device 1C, and the laser light L1 having the oscillation wavelength λ1 of the semiconductor laser 2 is used for crystal excitation, so that the crystal oscillation wavelength λ2 There is an apparatus configured to output light of (≠ λ1).

  Some of these apparatuses can output light with a pulse output and a large output of several kW, and are used for various types of processing. However, the light having the oscillation wavelength λ2 of the crystal becomes return light L4 and is coupled to the emission end face 4b of the optical fiber 4, and the optical fiber 4 is guided from the emission end face 4b side to the incident end face 4a side to the semiconductor laser device 1C. When incident, the return light L4 has a large output and thus has a large adverse effect on the semiconductor laser 2.

  For this reason, in the semiconductor laser device 1C of this example, the filter 5C is disposed obliquely with respect to the optical axis P1 between the aspheric lens 3b and the aspheric lens 3c. The filter 5C is a wavelength selection filter that transmits the laser light L1 with the wavelength λ1 emitted from the semiconductor laser 2 and reflects the return light L4 with the wavelength λ2 emitted from the optical fiber 4.

<Operation Example of Semiconductor Laser Device in Third Embodiment>
Next, an operation example of the semiconductor laser device 1C according to the third embodiment will be described with reference to FIG.

  The laser beam L1 emitted from the semiconductor laser 2 is converted into a horizontally elongated substantially elliptical beam shape by converting the radiation angle in the vertical direction to about 1/10 by the cylindrical lens 3a.

  Laser light L1 irradiated from the semiconductor laser 2 and transmitted through the cylindrical lens 3a is converted into parallel light by the aspherical lens 3b.

  The filter 5C disposed between the aspherical lens 3b and the aspherical lens 3c transmits the laser light L1 having the wavelength λ1 emitted from the semiconductor laser 2, so that it is emitted from the semiconductor laser 2, and the cylindrical lens 3a and the aspherical surface are emitted. The laser beam L1 shaped by passing through the lens 3b passes through the filter 5C and enters the aspheric lens 3c.

  Then, the laser light L 1 incident on the aspheric lens 3 c is condensed on the incident end face 4 a of the optical fiber 4 and enters the optical fiber 4. The light incident on the optical fiber 4 is guided from the incident end face 4a side to the outgoing end face 4b side. A part of the light guided from the incident end face 4 a side to the outgoing end face 4 b side of the optical fiber 4 is reflected by another device such as an optical fiber amplifier (not shown) connected to the optical fiber 4, thereby the optical fiber 4. The optical fiber 4 is guided from the exit end face 4b side to the entrance end face 4a side.

  The return light L4 guided through the optical fiber 4 from the exit end face 4b side to the entrance end face 4a side exits from the entrance end face 4a. The return light L4 emitted from the incident end face 4a of the optical fiber 4 is converted into parallel light by the aspheric lens 3c. The beam shape of the return light L4 is substantially circular.

  Here, when an optical fiber amplifier or the like is connected to the optical fiber 4 of the semiconductor laser device 1C, the optical fiber amplifier converts the light with the wavelength λ1 of the semiconductor laser 2 into the light with the wavelength λ2. The returned light L4 is light having a wavelength λ2.

  Since the filter 5C does not transmit light having the wavelength λ2, the return light L4 emitted from the incident end face 4a of the optical fiber 4 is blocked by the filter 5C and does not enter the semiconductor laser 2. Further, since the filter 5C is inclined with respect to the optical axis of the optical fiber 4, the return light L4 blocked and reflected by the filter 5C does not enter the incident end face 4a of the optical fiber 4 again.

  According to such a configuration, the return light L4 other than the oscillation wavelength of the semiconductor laser 2 guided through the optical fiber 4 from the exit end face 4b side to the entrance end face 4a side does not enter the semiconductor laser 2, and thus the semiconductor laser 2 Thus, it is possible to provide the semiconductor laser device 1C in which fluctuations in the oscillation spectrum, surface degradation, and occurrence of end face destruction are reduced.

<Configuration Example of Semiconductor Laser Device According to Fourth Embodiment>
FIG. 4 is a block diagram showing an example of a semiconductor laser device 1D according to the fourth embodiment. Next, a fourth embodiment of the semiconductor laser device will be described. The semiconductor laser device 1D of the fourth embodiment includes the filter 5A of the semiconductor laser device 1A of the first embodiment described in FIG. 1 and the semiconductor laser device 1B of the second embodiment described in FIG. Of the return light L2 reflected by the incident end face 4a of the optical fiber 4, and the return light L3 guided from the output end face 4b side to the incident end face 4a side and emitted from the incident end face 4a. Both can be cut off.

  Here, FIG. 4 schematically shows the configuration of the semiconductor laser device 1D, and parts having the same configuration as the semiconductor laser device 1A described in FIG. 1 and the semiconductor laser device 1B described in FIG. A description will be given.

  In the semiconductor laser device 1D, similarly to the semiconductor laser device 1A of the first embodiment, the cylindrical lens 3a and the aspheric lens 3b are disposed on the optical axis P1 of the semiconductor laser 2, and the aspheric lens 3c and the optical fiber. 4 is arranged such that the optical axis P2 is shifted parallel to the optical axis P1 of the semiconductor laser 2.

The laser light L1 emitted from the semiconductor laser 2 is shaped into a horizontally long and substantially elliptical beam shape by the cylindrical lens 3a, and is guided to the optical fiber 4 by the aspherical lens 3b and the aspherical lens 3c. As shown to b), it is comprised so that it may inject into the incident end surface 4a with incident angle (theta) ₂ .

The optical system is configured such that θ ₁ <θ _{2 where} θ ₁ is the spread angle (half angle) of the incident beam. Between the aspherical lens 3b and the aspherical lens 3c, the laser beam of the semiconductor laser 2 is formed. The optical path of the return light L2 reflected by L1 and the incident end face 4a of the optical fiber 4 is spatially separated.

  The filter 5A has a shape in which the laser light L1 of the semiconductor laser 2 separated from the optical path between the aspherical lens 3b and the aspherical lens 3c is transmitted, and the return light L2 reflected by the incident end face 4a of the optical fiber 4 is blocked. .

Further, the return light L3 guided through the optical fiber 4 from the exit end face 4b side to the entrance end face 4a, for example, by being guided by the optical fiber 4 and reflected by the exit end face 4b, is emitted from the entrance end face 4a at the radiation angle θ _3. Exit with

  The beam diameter of the return light L3, which is guided from the exit end face 4b side to the entrance end face 4a, exits from the entrance end face 4a, and is converted into parallel light by the aspheric lens 3c, is W2. The beam diameter in the Y-axis direction of the laser beam L1 irradiated from the semiconductor laser 2, shaped by the cylindrical lens 3a, and converted into parallel light by the aspheric lens 3b is defined as W1. The semiconductor laser device 1D has an optical system configured to satisfy W1 <W2, similarly to the semiconductor laser device 1B of the second embodiment.

  The filter 5B is configured such that the size W3 of the opening 6 in the Y-axis direction satisfies W1 <W3 <W2.

<Operation Example of Semiconductor Laser Device of Fourth Embodiment>
Next, an operation example of the semiconductor laser device 1D according to the fourth embodiment will be described with reference to FIG.

  The laser beam L1 emitted from the semiconductor laser 2 is converted into a horizontally elongated substantially elliptical beam shape by the vertical radiation angle being converted to about 1/10 by the cylindrical lens 3a, and parallel by the aspherical lens 3b. Converted to light.

  The filter 5A disposed between the aspherical lens 3b and the aspherical lens 3c is shaped to transmit the laser light L1 irradiated from the semiconductor laser 2, shaped by the cylindrical lens 3a and converted into parallel light by the aspherical lens 3b. Therefore, the laser beam L1 emitted from the semiconductor laser 2 passes through the filter 5A.

  Further, when the beam diameter in the Y-axis direction of the laser light L1 converted into parallel light by the aspheric lens 3b is W1, the filter 5B disposed between the aspheric lens 3b and the aspheric lens 3c has a Y-axis direction. Is provided with an opening 6 having a size of W3 (> W1), the laser light L1 transmitted through the filter 5A passes through the opening 6 of the filter 5B and enters the aspherical lens 3c.

Since the aspheric lens 3c and the optical fiber 4 are arranged to be shifted parallel to the optical axis P1 of the semiconductor laser 2, the laser light L1 emitted from the semiconductor laser 2 is incident on the incident angle θ ₂ by the aspheric lens 3c. The light is condensed on the incident end face 4 a of the optical fiber 4.

  Most of the laser light L1 collected on the incident end face 4a of the optical fiber 4 is incident on a core (not shown) of the optical fiber 4 and guided there. On the other hand, a part of the laser beam L1 condensed on the incident end face 4a of the optical fiber 4 is reflected by the incident end face 4a.

Laser light L1 converged on the entrance end face 4a of the optical fiber 4, is incident at an incident angle theta _2, the return light L2 reflected by the incident end surface 4a is reflected at the same reflection angle as the incident angle theta _2. Since θ ₁ <θ ₂ with respect to the spread angle θ ₁ (half angle) of the incident beam to the optical fiber 4, the laser light L 1 of the semiconductor laser 2 is between the aspheric lens 3 b and the aspheric lens 3 c. The optical path of the return light L2 reflected by the incident end face 4a of the optical fiber 4 is spatially separated. Then, the return light L2 reflected by the incident end face 4a of the optical fiber 4 is blocked by the filter 5A, and is prevented from entering the semiconductor laser 2 again.

  The light incident on the optical fiber 4 is guided from the incident end face 4a side to the outgoing end face 4b side. A part of the light guided from the incident end face 4a side to the outgoing end face 4b side of the optical fiber 4 becomes return light by being reflected by the outgoing end face 4b and the like, and the optical fiber 4 is moved from the outgoing end face 4b side to the incident end face 4a side. Waveguided.

  The return light L3 guided through the optical fiber 4 from the exit end face 4b side to the entrance end face 4a side exits from the entrance end face 4a. The return light L3 emitted from the incident end face 4a of the optical fiber 4 is converted into parallel light by the aspheric lens 3c.

  As described above, when the beam diameter of the return light L3 converted into parallel light by the aspherical lens 3c is W2, the size W3 in the Y-axis direction of the opening 6 of the filter 5B is such that W3 <W2. Thus, the return light L3 emitted from the incident end face 4a of the optical fiber 4 is blocked by the filter 5B at the portion outside the opening 6 of the filter 5B.

  A part of the return light L3 transmitted through the opening 6 of the filter 5B is blocked by the filter 5A. Thereby, the light quantity of the return light which irradiates the semiconductor laser 2 further decreases.

  According to such a configuration, it is possible to prevent the return light L2 reflected by the incident end face 4a of the optical fiber 4 from entering the semiconductor laser 2 again. In addition, a part of the return light L3 that is guided from the exit end face 4b side of the optical fiber 4 to the entrance end face 4a side and exits from the entrance end face 4a can be blocked. Thereby, it is possible to provide the semiconductor laser device 1D in which the fluctuation of the oscillation spectrum of the semiconductor laser 2, the surface degradation, and the occurrence of end face destruction are reduced.

  In the semiconductor laser device 1D of the fourth embodiment, the aspherical lens 3c and the optical fiber 4 are arranged so as to be shifted in parallel with the optical axis P1, but for example, oblique polishing with the incident end face 4a inclined. If a fiber is used, optical path separation can be realized without shifting the optical axis. Further, the filter 5A and the filter 5B may be configured integrally.

<Configuration Example of Semiconductor Laser Device of Fifth Embodiment>
FIG. 5 is a block diagram showing an example of a semiconductor laser device 1E according to the fifth embodiment. Next, a fifth embodiment of the semiconductor laser device will be described. The semiconductor laser device 1E of the fifth embodiment includes the filter 5A of the semiconductor laser device 1A of the first embodiment described in FIG. 1 and the semiconductor laser device 1C of the third embodiment described in FIG. The filter 5C is provided so that both the return light L2 reflected by the incident end face 4a of the optical fiber 4 and the return light L4 having a wavelength different from the oscillation wavelength of the semiconductor laser 2 can be blocked.

  Here, FIG. 5 schematically shows the configuration of the semiconductor laser device 1E, and the same reference numerals are given to parts having the same configuration as the semiconductor laser device 1A described in FIG. 1 and the semiconductor laser device 1C described in FIG. A description will be given.

  In the semiconductor laser device 1E, similarly to the semiconductor laser device 1A of the first embodiment, the cylindrical lens 3a and the aspheric lens 3b are arranged on the optical axis P1 of the semiconductor laser 2, and the aspheric lens 3c and the optical fiber. 4 is arranged such that the optical axis P2 is shifted parallel to the optical axis P1 of the semiconductor laser 2.

The laser light L1 emitted from the semiconductor laser 2 is shaped into a horizontally long and substantially elliptical beam shape by the cylindrical lens 3a, and is guided to the optical fiber 4 by the aspherical lens 3b and the aspherical lens 3c. as described in b), configured to be incident on the incident end surface 4a at an incident angle theta _2.

The optical system is configured such that θ ₁ <θ _{2 where} θ ₁ is the spread angle (half angle) of the incident beam. Between the aspherical lens 3b and the aspherical lens 3c, the laser beam of the semiconductor laser 2 is formed. The optical path of the return light L2 reflected by L1 and the incident end face 4a of the optical fiber 4 is spatially separated.

  The filter 5A has a shape in which the laser light L1 of the semiconductor laser 2 separated from the optical path between the aspherical lens 3b and the aspherical lens 3c is transmitted, and the return light L2 reflected by the incident end face 4a of the optical fiber 4 is blocked. .

  The filter 5C is a wavelength selection filter that transmits the laser light L1 with the wavelength λ1 emitted from the semiconductor laser 2 and reflects the light with a wavelength different from the wavelength λ1, and is inclined with respect to the optical axis P2 of the optical fiber 4. Be placed.

<Operation Example of Semiconductor Laser Device in Fifth Embodiment>
Next, an operation example of the semiconductor laser device 1E according to the fifth embodiment will be described with reference to FIG.

  The laser beam L1 emitted from the semiconductor laser 2 is converted into a horizontally elongated substantially elliptical beam shape by the vertical radiation angle being converted to about 1/10 by the cylindrical lens 3a, and parallel by the aspherical lens 3b. Converted to light.

  Since the filter 5C disposed between the aspherical lens 3b and the aspherical lens 3c transmits the laser light L1 having the wavelength λ1 emitted from the semiconductor laser 2, the laser light L1 emitted from the semiconductor laser 2 is filtered. It passes through 5C.

  The filter 5A is shaped to transmit the laser light L1 irradiated from the semiconductor laser 2, shaped by the cylindrical lens 3a and converted into parallel light by the aspherical lens 3b, and therefore the laser light L1 transmitted through the filter 5C is transmitted through the filter 5A. The light passes through the filter 5A and enters the aspherical lens 3c.

Since the aspheric lens 3c and the optical fiber 4 are arranged to be shifted parallel to the optical axis P1 of the semiconductor laser 2, the laser light L1 emitted from the semiconductor laser 2 is incident on the incident angle θ ₂ by the aspheric lens 3c. The light is condensed on the incident end face 4 a of the optical fiber 4.

  Most of the laser light L1 collected on the incident end face 4a of the optical fiber 4 is incident on a core (not shown) of the optical fiber 4 and guided there. On the other hand, a part of the laser beam L1 condensed on the incident end face 4a of the optical fiber 4 is reflected by the incident end face 4a.

Laser light L1 converged on the entrance end face 4a of the optical fiber 4, is incident at an incident angle theta _2, the return light L2 reflected by the incident end surface 4a is reflected at the same reflection angle as the incident angle theta _2. Since θ ₁ <θ ₂ with respect to the spread angle θ ₁ (half angle) of the incident beam to the optical fiber 4, the laser light L 1 of the semiconductor laser 2 is between the aspheric lens 3 b and the aspheric lens 3 c. The optical path of the return light L2 reflected by the incident end face 4a of the optical fiber 4 is spatially separated. Then, the return light L2 reflected by the incident end face 4a of the optical fiber 4 is blocked by the filter 5A, and is prevented from entering the semiconductor laser 2 again.

  The light incident on the optical fiber 4 is guided from the incident end face 4a side to the outgoing end face 4b side. A part of the light guided from the incident end face 4 a side to the outgoing end face 4 b side of the optical fiber 4 is reflected by another device such as an optical fiber amplifier (not shown) connected to the optical fiber 4, thereby the optical fiber 4. The optical fiber 4 is guided from the exit end face 4b side to the entrance end face 4a side.

  Here, when an optical fiber amplifier is connected to the optical fiber 4 of the semiconductor laser device 1E, the optical fiber amplifier converts the light with the wavelength λ1 of the semiconductor laser 2 into the light with the wavelength λ2, so that the optical fiber amplifier generates the optical fiber amplifier. The return light becomes light of wavelength λ2.

  The return light L4 guided through the optical fiber 4 from the exit end face 4b side to the entrance end face 4a side exits from the entrance end face 4a. The return light L4 emitted from the incident end face 4a of the optical fiber 4 is converted into parallel light by the aspheric lens 3c.

  Part of the return light L4 converted into parallel light by the aspheric lens 3c is blocked by the filter 5A. Further, since the filter 5C does not transmit the light having the wavelength λ2, the return light L4 having the wavelength λ2 transmitted through the filter 5A is blocked by the filter 5C and does not enter the semiconductor laser 2. Furthermore, since the filter 5C is inclined with respect to the optical axis P2 of the optical fiber 4, the return light L4 blocked and reflected by the filter 5C does not enter the incident end face 4a of the optical fiber 4 again.

  According to such a configuration, it is possible to prevent the return light L2 reflected by the incident end face 4a of the optical fiber 4 from entering the semiconductor laser 2 again. Further, the return light L4 other than the oscillation wavelength of the semiconductor laser 2 guided through the optical fiber 4 from the emission end face 4b side to the incident end face 4a side does not enter the semiconductor laser 2. As a result, it is possible to provide the semiconductor laser device 1E in which the fluctuation of the oscillation spectrum of the semiconductor laser 2, the surface deterioration, and the occurrence of end face destruction are reduced.

  In the semiconductor laser device 1E of the fifth embodiment, the aspherical lens 3c and the optical fiber 4 are arranged so as to be shifted parallel to the optical axis P1, but for example, oblique polishing with the incident end face 4a inclined. If a fiber is used, optical path separation can be realized without shifting the optical axis.

<Configuration Example of Semiconductor Laser Device in Sixth Embodiment>
FIG. 6 is a block diagram showing an example of a semiconductor laser device 1F according to the sixth embodiment. Next, a sixth embodiment of the semiconductor laser device will be described. The semiconductor laser device 1F of the sixth embodiment includes the filter 5B of the semiconductor laser device 1B of the second embodiment described in FIG. 2 and the semiconductor laser device 1C of the third embodiment described in FIG. The return light L3 guided from the exit end face 4b side to the entrance end face 4a side and emitted from the entrance end face 4a and the return light L4 having a wavelength different from the oscillation wavelength of the semiconductor laser 2 are provided. Both can be cut off.

  Here, FIG. 6 schematically shows the configuration of the semiconductor laser device 1F, and parts having the same configuration as the semiconductor laser device 1B described in FIG. 2 and the semiconductor laser device 1C described in FIG. A description will be given.

  Similar to the semiconductor laser device 1B of the second embodiment, the semiconductor laser device 1F has the aspheric lens 3c and the optical fiber 4 on the optical axis P1 of the semiconductor laser 2 together with the cylindrical lens 3a and the aspheric lens 3b. Be placed.

  As described above, a part of the laser light L1 irradiated from the semiconductor laser 2 and incident on the optical fiber 4 becomes return light by being reflected by the emission end face 4b of the optical fiber 4, and the like, and enters the incident end face 4a from the emission end face 4b side. And is emitted from the incident end face 4a.

  The beam diameter of the return light L3 (L4) emitted from the incident end face 4a of the optical fiber 4 and converted into parallel light by the aspherical lens 3c is W2. The beam diameter in the Y-axis direction of the laser beam L1 irradiated from the semiconductor laser 2, shaped by the cylindrical lens 3a, and converted into parallel light by the aspheric lens 3b is defined as W1. As in the semiconductor laser device 1B of the second embodiment, the semiconductor laser device 1F has an optical system configured to satisfy W1 <W2.

  The filter 5B is configured such that the size W3 of the opening 6 in the Y-axis direction satisfies W1 <W3 <W2.

  The filter 5C is a wavelength selection filter that transmits the laser light L1 with the wavelength λ1 emitted from the semiconductor laser 2 and reflects the light with a wavelength different from the wavelength λ1, and is inclined with respect to the optical axis P1 of the optical fiber 4. Be placed.

<Operation Example of Semiconductor Laser Device of Sixth Embodiment>
Next, an operation example of the semiconductor laser device 1F according to the sixth embodiment will be described with reference to FIG.

  The laser beam L1 emitted from the semiconductor laser 2 is converted into a horizontally elongated substantially elliptical beam shape by the vertical radiation angle being converted to about 1/10 by the cylindrical lens 3a, and parallel by the aspherical lens 3b. Converted to light.

  Since the filter 5C disposed between the aspherical lens 3b and the aspherical lens 3c transmits the laser light L1 having the wavelength λ1 emitted from the semiconductor laser 2, the laser light L1 emitted from the semiconductor laser 2 is filtered. It passes through 5C.

  Further, when the beam diameter in the Y-axis direction of the laser light L1 converted into parallel light by the aspheric lens 3b is W1, the filter 5B disposed between the aspheric lens 3b and the aspheric lens 3c has a Y-axis direction. Is provided with an opening 6 having a size of W3 (> W1), the laser light L1 transmitted through the filter 5C passes through the opening 6 of the filter 5B and enters the aspherical lens 3c.

  The laser beam L1 incident on the aspheric lens 3c is condensed on the incident end surface 4a of the optical fiber 4. The light incident on the optical fiber 4 is guided from the incident end face 4a side to the outgoing end face 4b side. A part of the light guided from the incident end face 4a side to the outgoing end face 4b side of the optical fiber 4 becomes return light by being reflected by the outgoing end face 4b and the like, and the optical fiber 4 is moved from the outgoing end face 4b side to the incident end face 4a side. Waveguided.

  The return light L3 guided through the optical fiber 4 from the exit end face 4b side to the entrance end face 4a side exits from the entrance end face 4a. The return light L3 emitted from the incident end face 4a of the optical fiber 4 is converted into parallel light by the aspheric lens 3c.

  As described above, when the beam diameter of the return light L3 converted into parallel light by the aspherical lens 3c is W2, the size W3 in the Y-axis direction of the opening 6 of the filter 5B is such that W3 <W2. Thus, the return light L3 emitted from the incident end face 4a of the optical fiber 4 is blocked by the filter 5B at the portion outside the opening 6 of the filter 5B.

  Here, when an optical fiber amplifier is connected to the optical fiber 4 of the semiconductor laser device 1F, the optical fiber amplifier converts the light with the wavelength λ1 of the semiconductor laser 2 into the light with the wavelength λ2, so that the optical fiber amplifier generates the optical fiber amplifier. The return light becomes light of wavelength λ2.

  Since the filter 5C does not transmit the light having the wavelength λ2, the return light L4 having the wavelength λ2 transmitted through the filter 5B is blocked by the filter 5C and does not enter the semiconductor laser 2. Further, since the filter 5C is inclined with respect to the optical axis of the optical fiber 4, the return light L4 blocked and reflected by the filter 5C does not enter the incident end face 4a of the optical fiber 4 again.

  According to such a configuration, it is possible to block part of the return light L3 that is guided from the exit end face 4b side of the optical fiber 4 to the entrance end face 4a side and exits from the entrance end face 4a. Further, the return light L4 other than the oscillation wavelength of the semiconductor laser 2 does not enter the semiconductor laser 2. As a result, it is possible to provide the semiconductor laser device 1E in which the fluctuation of the oscillation spectrum of the semiconductor laser 2, the surface deterioration, and the occurrence of end face destruction are reduced.

<Configuration Example of Semiconductor Laser Device in Seventh Embodiment>
FIG. 7 is a block diagram showing an example of a semiconductor laser device 1G of the seventh embodiment. Next, a seventh embodiment of the semiconductor laser device will be described. The semiconductor laser device 1G of the seventh embodiment includes the filter 5A of the semiconductor laser device 1A of the first embodiment described in FIG. 1 and the semiconductor laser device 1B of the second embodiment described in FIG. 3 and the filter 5C of the semiconductor laser device 1C according to the third embodiment described with reference to FIG. 3, and the return light L2 reflected by the incident end face 4a of the optical fiber 4 and the optical fiber 4 through the outgoing end face 4b. The return light L3 guided from the side to the incident end face 4a side and emitted from the incident end face 4a and the return light L4 having a wavelength different from the oscillation wavelength of the semiconductor laser 2 can be blocked.

  7 schematically shows the configuration of the semiconductor laser device 1G, which is equivalent to the semiconductor laser device 1A described in FIG. 1, the semiconductor laser device 1B described in FIG. 2, and the semiconductor laser device 1C described in FIG. About the site | part which has a structure, the same number is attached | subjected and demonstrated.

  In the semiconductor laser device 1G, similarly to the semiconductor laser device 1A of the first embodiment, the cylindrical lens 3a and the aspheric lens 3b are disposed on the optical axis P1 of the semiconductor laser 2, and the aspheric lens 3c and the optical fiber. 4 is arranged such that the optical axis P2 is shifted parallel to the optical axis P1 of the semiconductor laser 2.

The laser light L1 emitted from the semiconductor laser 2 is shaped into a horizontally long and substantially elliptical beam shape by the cylindrical lens 3a, and is guided to the optical fiber 4 by the aspherical lens 3b and the aspherical lens 3c. b) as described in such configured to be incident on the incident end surface 4a at an incident angle theta _2.

The optical system is configured such that θ ₁ <θ _{2 where} θ ₁ is the spread angle (half angle) of the incident beam. Between the aspherical lens 3b and the aspherical lens 3c, the laser beam of the semiconductor laser 2 is formed. The optical path of the return light L2 reflected by L1 and the incident end face 4a of the optical fiber 4 is spatially separated.

  The filter 5A has a shape in which the laser light L1 of the semiconductor laser 2 separated from the optical path between the aspherical lens 3b and the aspherical lens 3c is transmitted, and the return light L2 reflected by the incident end face 4a of the optical fiber 4 is blocked. .

Further, such as by reflected at the light output end face 4b of the optical fiber 4, the return light L3 guided to the incident end surface 4a of the optical fiber 4 from the exit end face 4b side is emitted at emission angle theta ₃ from the incident end surface 4a.

  The beam diameter of the return light L3, which is guided from the exit end face 4b side to the entrance end face 4a, exits from the entrance end face 4a, and is converted into parallel light by the aspheric lens 3c, is W2. The beam diameter in the Y-axis direction of the laser beam L1 irradiated from the semiconductor laser 2, shaped by the cylindrical lens 3a, and converted into parallel light by the aspheric lens 3b is defined as W1. The semiconductor laser device 1G has an optical system so that W1 <W2, as in the semiconductor laser device 1B of the second embodiment.

  The filter 5B is configured such that the size W3 of the opening 6 in the Y-axis direction satisfies W1 <W3 <W2.

  The filter 5C is a wavelength selection filter that transmits the laser light L1 with the wavelength λ1 emitted from the semiconductor laser 2 and reflects the light with a wavelength different from the wavelength λ1, and is inclined with respect to the optical axis P2 of the optical fiber 4. Be placed.

<Operation Example of Semiconductor Laser Device in Seventh Embodiment>
Next, an operation example of the semiconductor laser device 1G according to the seventh embodiment will be described with reference to FIG.

  The laser beam L1 emitted from the semiconductor laser 2 is converted into a horizontally elongated substantially elliptical beam shape by the vertical radiation angle being converted to about 1/10 by the cylindrical lens 3a, and parallel by the aspherical lens 3b. Converted to light.

  Since the filter 5C disposed between the aspherical lens 3b and the aspherical lens 3c transmits the laser light L1 having the wavelength λ1 emitted from the semiconductor laser 2, the laser light L1 emitted from the semiconductor laser 2 is filtered. It passes through 5C.

  The filter 5A is shaped to transmit the laser light L1 irradiated from the semiconductor laser 2, shaped by the cylindrical lens 3a and converted into parallel light by the aspherical lens 3b, and therefore the laser light L1 transmitted through the filter 5C is transmitted through the filter 5A. , And passes through the filter 5A.

  Further, if the beam diameter in the Y-axis direction of the laser light L1 converted into parallel light by the aspherical lens 3b is W1, the filter 5B has an opening 6 having a size of W3 (> W1) in the Y-axis direction. Thus, the laser beam L1 that has passed through the filter 5A passes through the opening 6 of the filter 5B and enters the aspherical lens 3c.

Since the aspheric lens 3c and the optical fiber 4 are arranged to be shifted parallel to the optical axis P1 of the semiconductor laser 2, the laser light L1 emitted from the semiconductor laser 2 is incident on the incident angle θ ₂ by the aspheric lens 3c. The light is condensed on the incident end face 4 a of the optical fiber 4.

  Most of the laser light L1 collected on the incident end face 4a of the optical fiber 4 is incident on a core (not shown) of the optical fiber 4 and guided there. On the other hand, a part of the laser beam L1 condensed on the incident end face 4a of the optical fiber 4 is reflected by the incident end face 4a.

Laser light L1 converged on the entrance end face 4a of the optical fiber 4, is incident at an incident angle theta _2, the return light L2 reflected by the incident end surface 4a is reflected at the same reflection angle as the incident angle theta _2. Since θ ₁ <θ ₂ with respect to the spread angle θ ₁ (half angle) of the incident beam to the optical fiber 4, the laser light L 1 of the semiconductor laser 2 is between the aspheric lens 3 b and the aspheric lens 3 c. The optical path of the return light L2 reflected by the incident end face 4a of the optical fiber 4 is spatially separated. Then, the return light L2 reflected by the incident end face 4a of the optical fiber 4 is blocked by the filter 5A, and is prevented from entering the semiconductor laser 2 again.

  The light incident on the optical fiber 4 is guided from the incident end face 4a side to the outgoing end face 4b side. A part of the light guided from the incident end face 4a side to the outgoing end face 4b side of the optical fiber 4 becomes return light by being reflected by the outgoing end face 4b and the like, and the optical fiber 4 is moved from the outgoing end face 4b side to the incident end face 4a side. Waveguided.

  The return light L3 guided through the optical fiber 4 from the exit end face 4b side to the entrance end face 4a side exits from the entrance end face 4a. The return light L3 emitted from the incident end face 4a of the optical fiber 4 is converted into parallel light by the aspheric lens 3c.

  As described above, when the beam diameter of the return light L3 converted into parallel light by the aspherical lens 3c is W2, the size W3 in the Y-axis direction of the opening 6 of the filter 5B is such that W3 <W2. Thus, the return light L3 emitted from the incident end face 4a of the optical fiber 4 is blocked by the filter 5B at the portion outside the opening 6 of the filter 5B. A part of the return light L3 that has passed through the opening 6 of the filter 5B is blocked by the filter 5A.

  Here, when an optical fiber amplifier is connected to the optical fiber 4 of the semiconductor laser device 1G, the optical fiber amplifier converts the light with the wavelength λ1 of the semiconductor laser 2 into the light with the wavelength λ2. The return light becomes light of wavelength λ2.

  Since the filter 5C does not transmit light of wavelength λ2, the return light L4 of wavelength λ2 that has passed through the filters 5B and 5A is blocked by the filter 5C and does not enter the semiconductor laser 2. Further, since the filter 5C is inclined with respect to the optical axis of the optical fiber 4, the return light L4 blocked and reflected by the filter 5C does not enter the incident end face 4a of the optical fiber 4 again.

  According to such a configuration, it is possible to prevent the return light L2 reflected by the incident end face 4a of the optical fiber 4 from entering the semiconductor laser 2 again. In addition, a part of the return light L3 that is guided from the exit end face 4b side of the optical fiber 4 to the entrance end face 4a side and exits from the entrance end face 4a can be blocked. Further, the return light L4 other than the oscillation wavelength of the semiconductor laser 2 does not enter the semiconductor laser 2. As a result, it is possible to provide the semiconductor laser device 1G in which the fluctuation of the oscillation spectrum of the semiconductor laser 2, the surface degradation, and the occurrence of end face destruction are reduced.

  In the semiconductor laser device 1G of the seventh embodiment, the aspherical lens 3c and the optical fiber 4 are arranged so as to be shifted parallel to the optical axis. If is used, optical path separation can be realized without shifting the optical axis. Further, the filter 5A and the filter 5B may be configured integrally.

  The present invention is applied to a semiconductor laser device that outputs light used for processing.

It is a block diagram which shows an example of 1 A of semiconductor laser apparatuses of 1st Embodiment. It is a block diagram which shows an example of the semiconductor laser apparatus 1B of 2nd Embodiment. It is a block diagram which shows an example of 1 C of semiconductor laser apparatuses of 3rd Embodiment. It is a block diagram which shows an example of semiconductor laser apparatus 1D of 4th Embodiment. It is a block diagram which shows an example of the semiconductor laser apparatus 1E of 5th Embodiment. It is a block diagram which shows an example of the semiconductor laser apparatus 1F of 6th Embodiment. It is a block diagram which shows an example of the semiconductor laser apparatus 1G of 7th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser apparatus, 2 ... Semiconductor laser, 3a ... Cylindrical lens, 3b ... Aspherical lens, 3c ... Aspherical lens, 4 ... Optical fiber, 5 ... Filter , 6 ... opening

Claims (11)

A light source that emits laser light;
A light guide for guiding laser light;
An optical element that shapes the laser light emitted from the light source and focuses the light on the light guide;
A semiconductor laser device comprising: a filter that transmits laser light emitted from the light source and shaped by the optical element, and that blocks return light generated by the light guide. An optical path separating unit that separates the optical path of the laser light emitted from the light source and shaped by the optical element and the return light reflected by the incident end face of the light guide, and the filter is disposed in the optical path of the return light The semiconductor laser device according to claim 1. The optical element includes a first lens that narrows a vertical radiation angle of laser light emitted from the light source and shapes the laser light into a horizontally long beam shape, and laser light that has passed through the first lens is used as the light guide. At least a second lens for condensing,
The optical path separating means is configured by obliquely entering laser light shaped by the first lens and condensed by the second lens into the incident end face of the light guide. Semiconductor laser device. The optical element includes a first lens that narrows a vertical radiation angle of laser light emitted from the light source and shapes the laser light into a horizontally long beam shape, and laser light that has passed through the first lens is used as the light guide. At least a second lens for condensing is provided, and the beam shape of the laser light shaped by the first lens is made smaller than the beam shape of the return light guided by the light guide and emitted from the incident end face. Configured,
The semiconductor laser device according to claim 1, wherein the filter includes an opening through which the laser light shaped by the first lens passes. 2. The semiconductor according to claim 1, wherein the filter is a wavelength selection filter that allows a laser beam having a wavelength emitted from the light source to pass through and is inclined with respect to a vertical plane of an optical axis of the light guide. Laser device. The laser light shaped by the optical element is obliquely incident on the incident end face of the light guide to separate the optical path of the laser light emitted from the light source and the return light reflected by the incident end face of the light guide. With optical path separating means,
The optical element includes a first lens that narrows a vertical radiation angle of laser light emitted from the light source and shapes the laser light into a horizontally long beam shape, and laser light that has passed through the first lens is used as the light guide. At least a second lens for condensing is provided, and the beam shape of the laser light shaped by the first lens is made smaller than the beam shape of the return light guided by the light guide and emitted from the incident end face. Configured,
The filter includes a first filter disposed in an optical path of the return light;
The semiconductor laser device according to claim 1, further comprising a second filter having an opening through which the laser light shaped by the first lens passes. The semiconductor laser device according to claim 6, wherein the first filter and the second filter are integrally formed. The laser light shaped by the optical element is obliquely incident on the incident end face of the light guide to separate the optical path of the laser light emitted from the light source and the return light reflected by the incident end face of the light guide. With optical path separating means,
The filter includes a first filter disposed in the optical path of the return light, and a second filter through which the laser light having a wavelength emitted from the light source passes, and the second filter passes through the light guide light. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is arranged to be inclined with respect to a vertical plane of the shaft. The optical element collects, in the light guide, a first lens that narrows the vertical emission angle of the laser light emitted from the light source and shapes the laser light into a horizontally elongated beam shape, and the laser light that has passed through the first lens. At least a second lens that emits light is provided, and the beam shape of the laser light shaped by the first lens is configured to be smaller than the beam shape of the return light that is guided by the light guide and emitted from the incident end face. And
The filter includes a first filter having an opening through which laser light shaped by the first lens passes, and a second filter through which laser light having a wavelength emitted from the light source passes, The semiconductor laser device according to claim 1, wherein the filter is disposed to be inclined with respect to a vertical plane of the optical axis of the light guide. The laser light shaped by the optical element is obliquely incident on the incident end face of the light guide to separate the optical path of the laser light emitted from the light source and the return light reflected by the incident end face of the light guide. With optical path separating means,
The optical element includes a first lens that narrows a vertical radiation angle of laser light emitted from the light source and shapes the laser light into a horizontally long beam shape, and laser light that has passed through the first lens is used as the light guide. At least a second lens for condensing is provided, and the beam shape of the laser light shaped by the first lens is made smaller than the beam shape of the return light guided by the light guide and emitted from the incident end face. Configured,
The filter includes a first filter disposed in the optical path of the return light, a second filter having an opening through which the laser light shaped by the first lens passes, and a wavelength of light emitted from the light source. The semiconductor laser device according to claim 1, further comprising a third filter through which laser light passes, wherein the third filter is disposed to be inclined with respect to a vertical plane of an optical axis of the light guide. The semiconductor laser device according to claim 10, wherein the first filter and the second filter are integrally formed.

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