JP2000141073A - Ld array optical wave guide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a LD array optical waveguide to efficiently converge laser beams emitted from a LD array and guide them to an optical fiber. SOLUTION: Laser beams emitted from a LD array 1 is made into parallel beams by a fiber lense 6 and then is made incident to a sector kaleido 4 to be converged. Onto the emitting end surface of the sector kaleido 4, a taper fiber 5 having an incidetal end surface with a larger diameter than that of this emitting end surface is connected, so waveguiding is made with less vignetting due to the difference of NA between the two.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LD array optical waveguide that efficiently guides a laser beam from an LD array to an optical fiber and uses the laser beam for laser processing or the like.

[0002]

2. Description of the Related Art In order to collect laser light emitted from each LD of an LD array configured by arranging a plurality of LDs (laser diodes) on a straight line and use it for laser marking, laser processing, and the like. An LD array optical waveguide is used.

FIG. 7 shows the structure of an LD array optical waveguide according to the prior art. Laser light emitted from each LD of an LD array 21 is condensed by a fan-shaped halide 22, and the condensed laser light is emitted. The light is guided to an optical fiber 23 connected to the exit end face of the fan-shaped carbide 22, guided to an arbitrary position by the optical fiber 23,
Used for required purposes.

[0004]

However, the light condensed by the fan-shaped carbide does not focus on the emission end face, but emits surface light at the aperture diameter of the emission end face, so that the laser light spreads on the emission end face. Therefore, there is a problem that a waveguide loss occurs during the waveguide to the ordinary optical fiber. That is, a normal optical fiber has its numerical aperture: NA =
Since it is 0.2, vignetting of the laser light occurs due to the NA difference, and a waveguide loss of 50% or more occurs. FIG. 7 (b)
As shown in the side view, the laser light is repeatedly reflected and guided on the upper and lower surfaces of the fan-shaped carbide, so that a loss due to the reflection occurs and a waveguide loss occurs due to an NA difference in the vertical direction.

An object of the present invention is to provide an LD array optical waveguide in which laser light emitted from an LD array can be guided to an optical fiber with a reduced waveguide loss.

[0006]

According to a first aspect of the present invention for achieving the above object, a laser beam emitted from an LD array configured by arranging a plurality of laser diodes in a straight line is collected. In an LD array optical waveguide for guiding an optical fiber, the width of the incident end face corresponding to the width of the LD array in the laser diode arrangement direction is formed to have a taper angle of 1/5 to 1/10 toward the emission end face. The laser beam emitted from the LD array and spread in the array direction by the fan-shaped carbide is collected, and has an incident NA value larger than a half of the emission NA value of the emission end face of the fan-shaped carbide. NA value of price width x
The fiber is formed so as to be guided to a tapered fiber satisfying (incidence diameter / emission diameter) ≦ NA specific to the fiber].

According to this configuration, the laser light emitted from the LD array is condensed by the fan-shaped carbide, and is incident on the tapered fiber formed based on the above conditions from the emission end face of the fan-shaped carbide. NA
The occurrence of vignetting due to the difference is small, and the laser light condensed by the fan-shaped carbide can be efficiently guided to the optical fiber.

According to a second aspect of the present invention for achieving the above object, a laser beam emitted from an LD array configured by arranging a plurality of laser diodes on a straight line is collected and guided to an optical fiber. In the LD array optical waveguide, the laser beam emitted from the LD array is condensed by the sector-shaped carbide, and the laser beam emitted from the LD array is converged toward the center by a tapered fiber formed on the emission end face of the sector-shaped crystal so that the refractive index increases toward the center. The laser light emitted from the tapered fiber is focused through a first condenser lens having a combination of lenses having different focal length ratios. It is guided to an arbitrary position by an optical fiber formed to be higher in the center direction, and lenses with different focal length ratios are combined. Characterized by comprising configured to refocus light through a second condenser lens which has.

According to this configuration, the laser light condensed by the fan-shaped halide is condensed so that the light density increases toward the center and guided to the optical fiber, and the optical fiber has a refractive index higher toward the center. The laser light having a higher light density at the center is obtained by being formed in the center, and the laser light having an extremely high peak density is obtained because the laser light is re-focused by the second condenser lens.
This can be used for laser processing or the like.

In each of the above structures, by arranging a fiber lens between the LD array and the fan-shaped carbide, the laser light emitted from the LD array is converted by the fiber lens from the parallel light or the output end face of the fan-shaped carbide. The light is focused so that it is focused outside and can be incident on the fan-shaped halide. Since it is focused, there is no repetition of reflection on the upper and lower surfaces of the fan-shaped halide, and there is no loss due to the repeated reflection, and there is no difference due to NA difference. Wave loss is also reduced.

According to a third aspect of the present invention, a laser beam emitted from an LD array having a plurality of laser diodes arranged in a straight line is collected and guided to an optical fiber. In the LD array optical waveguide, the incident end face of the trapezoidal carbide is arranged close to the emission end face of the LD array, and the laser light emitted from each laser diode of the LD array is located outside the emission end face of the trapezoidal carbide. LD to cross at the center point
Each laser diode is provided on an array.

According to this configuration, since the entrance end face of the trapezoidal carbide is arranged in close contact with the LD array, there is no waveguide loss of laser light between them, and the direction of each laser diode on the LD array is changed to the trapezoidal carbide. Since the laser beams are arranged so as to intersect at the center point outside the emission end face of the trapezoidal waveguide, the laser light is guided to the optical fiber connected to the emission end face of the trapezoidal carbide without waveguide loss.

In the above configuration, the trapezoidal kalide is formed of a lens material whose refractive index increases toward the end in the thickness direction, so that there is no reflection on the wall surface of the trapezoidal kalide and the laser light is focused. Therefore, the output NA can be reduced and the coupling efficiency to the optical fiber can be improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
The embodiment described below is an example embodying the present invention, and does not limit the technical scope of the present invention.

FIG. 1 is a block diagram of a first embodiment of the present invention.
FIG. 3A is a plan view, and FIG. 3B is a side view, showing a configuration of a D-array optical waveguide.

In FIG. 1, an LD array 1 includes a plurality of L
D (laser diodes) 2 are arranged in a straight line, and the laser light emitted from the LD array 1 is converted into parallel light by a fiber lens 6 as shown in FIG. From the incident end face. The fan-shaped callide 4 is formed so as to have a taper angle in which the width of the incident end face on the fiber lens 6 side decreases to 1/5 to 1/10 toward the output end face, and the laser beam incident from the incident end face is formed. The light is condensed and emitted from the emission end face. The laser light condensed by the fan-shaped carbide 4 is incident on a tapered fiber 5 connected to the emission end face. This tapered fiber 5 is formed such that the diameter of the incident end face thereof is larger than the diameter of the exit end face of the fan-shaped carbide 4, and has an incident NA value larger than a half of the outgoing NA value of the fan-shaped carbide 4. It is formed so as to satisfy the following expression (1) so as not to exceed the NA value inherent to the material forming the fiber.

NA value of half width of output NA of fan-shaped carbide × (input diameter / output diameter) ≦ NA specific to fiber.
(1) In the above configuration, since the spread of the laser light emitted from the LD array 1 is converted into parallel light by the fiber lens 6 and is incident on the fan-shaped halide 4, the coupling efficiency can be improved without loss due to vignetting. .

Further, since the diameter of the input end face of the tapered fiber 5 is formed larger than the diameter of the output end face of the fan-shaped carbide 4, vignetting due to NA difference is small and waveguide loss of laser light is reduced, and the tapered structure is used. The light density of the laser light can be increased by the light condensing effect. If the tapered fiber 5 is of a graded index type having a higher refractive index at the center, incident light obliquely can be directed toward the center, and the light density at the center can be further improved.

FIG. 2 shows a configuration in which a high NA lens 7 is provided in place of the tapered fiber 5 in the configuration of the first embodiment. The light is condensed by the high NA lens 7 and made incident on the optical fiber 8. The optical fiber 8 is more preferably of a tapered type, but the coupling efficiency is not greatly reduced even if it is of a normal parallel type.

FIG. 3 is a circuit diagram showing an L according to a second embodiment of the present invention.
FIG. 3A is a plan view, and FIG. 3B is a side view, showing a configuration of a D-array optical waveguide.

In FIG. 3, the light emitting surface of the LD array 10 is configured such that the incident end face of the trapezoidal carbide 9 is close to the light emitting surface, and the width of the trapezoidal halide 9 on the incident end face side is made equal to the width of the LD array 10. The width of the outgoing end face is 1 of the width of the incoming end face.
/ 5 to 1/10. LD array 1
The plurality of LD elements 2 arranged in 0 are arranged in such a direction that the laser light emitted from each LD element 2 intersects at a position f outside the emission end face of the trapezoidal carbide 9.

By arranging the trapezoidal carbide 9 close to the LD array 10 as described above, the waveguide loss between them is small, and the ratio of the exit end face to the entrance end face of the trapezoidal carbide 9 becomes 1/5 to 1/10. By setting the width of the trapezoid as described above, the power loss can be reduced and the density of the laser beam can be increased. In addition, the laser light is trapezoidal
Are set so as to intersect at a position f outside the emission end face of the trapezoidal carbide 9, so that the light can be guided to the optical fiber connected to the emission end face of the trapezoidal carbide 9 without greatly reducing the coupling efficiency.

As shown in FIG. 3 (c), the trapezoidal carbide 9a is formed using a Ge-doped glass substrate so that the refractive index increases toward the end in the thickness direction. Can be. Since the refractive index can be adjusted by the ratio of the Ge doping, by increasing the refractive index toward the end in the thickness direction, the laser light can be focused without being reflected on the wall surface, and coupling to the optical fiber can be performed. Efficiency can be significantly improved.

FIG. 4 is a block diagram of a third embodiment of the present invention.
FIG. 5 shows the configuration of a D-array optical waveguide.
(A) to (e).

In FIG. 4, the laser light emitted from the LD array 1 is converted into parallel light by the fiber lens 6 and is incident on the fan-shaped halide 4. The laser light is condensed by the fan-shaped carbide 4, and the intensity distribution of the laser light at the emission end face is φ1.5 m as shown in FIG.
m and is incident on the tapered fiber 5. Since the refractive index distribution of the tapered fiber 5 becomes higher toward the center, the intensity distribution of the laser beam has a higher intensity distribution at the center as shown in FIG. The light is focused on the end face with a diameter of 0.6 mm. When the laser light emitted from the tapered fiber 5 is re-focused by the first condenser lens 11 having a focal length ratio of 3: 1, FIG.
Since the light density at the central portion is increased as shown in FIG. 3C, the light is incident on the optical fiber 12. Since the incident diameter of the optical fiber 12 is φ0.2 mm, vignetting occurs in a portion where the light density is low in the peripheral portion indicated by oblique lines, but the optical fiber 12 is configured so that the central portion where the light intensity is high becomes higher as the refractive index becomes closer to the center. As a result, the light density at the center further increases, and the light is condensed to φ0.1 mm at the emission end of the optical fiber 12 as shown in FIG. A second condenser lens 1 having this laser beam set to a focal length ratio of 2: 1
When the light is condensed by No. 3, a laser light beam having an extremely high peak density is output as shown in FIG.

In each of the above-described configurations, by arranging the oscillation plate 14 between the fan-shaped carbide 4 and the tapered fiber 5 as shown in FIG. 6, vignetting due to a difference in NA can be reduced. The oscillation plate 14
As shown, fan-shaped callide 4 and tapered fiber 5
The laser light which is disposed at both ends of the connection position with the laser beam and whose reflection angle in the fan-shaped carbide 4 is increased is made into parallel light and is incident on the tapered fiber 5, so that the vignetting due to the NA difference is reduced.

When the wavelength of the laser beam emitted from the LD 2 is 808 nm, the oscillation plate 14
In the 1-2% doped 0.5~1mm thick plates cut parallel flat plate YVO _4, and subjected to 808nmAR coat and 1064nm total reflection coating on the incident surface of the laser beam, on the opposite surface of from 90 to 98% Those having a 1064 nm reflection coat are preferable, and the conversion efficiency is 20 to 40%.
Is obtained.

[0028]

As described above, according to the present invention, the LD
Since the laser light emitted from the array can be efficiently condensed and guided to the optical fiber with reduced waveguide loss, a laser beam with a high light density can be obtained from the LD array.

[Brief description of the drawings]

FIG. 1A is a plan view and FIG. 1B is a side view showing a configuration of an LD array optical waveguide according to a first embodiment.

FIGS. 2A and 2B show a modification of the configuration of the first embodiment, wherein FIG. 2A is a plan view and FIG.

3A is a plan view, FIG. 3B is a side view, and FIG. 3C is a side view of a modification of the LD array optical waveguide according to the second embodiment.

FIG. 4 is a perspective view showing a configuration of an LD array optical waveguide according to a third embodiment.

FIG. 5 is a graph showing a light distribution at positions indicated by (a) to (e) in the same configuration.

FIG. 6 is a plan view showing a configuration in which an oscillation plate is provided between a fan-shaped callide and a tapered fiber.

7A is a plan view and FIG. 7B is a side view showing a configuration of an LD array optical waveguide according to the related art.

[Explanation of symbols]

 Reference Signs List 1, 10 LD array 2 LD (laser diode) 4 fan-shaped kalide 5 tapered fiber 6 fiber lens 8, 12 optical fiber 9 trapezoidal kalide 11 first condenser lens 13 second condenser lens 14 oscillation plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H037 BA03 BA05 CA17 CA37 4E068 CA05 CD02 CD05 CD08 CD13 CE08 CK01 5F073 AB02 AB12 AB27 AB28 AB29 BA09

Claims (5)

[Claims] 1. An LD array optical waveguide for condensing laser light emitted from an LD array configured by arranging a plurality of laser diodes on a straight line and guiding the laser light to an optical fiber. The width of the incident end face corresponding to the width in the arrangement direction is 1/5 to 1/1 toward the output end face.
The laser beam emitted from the LD array and spread in the array direction is condensed by the fan-shaped carbide formed at the taper angle decreasing to 0, and has an incident NA value larger than half the emission NA of the emission end face of the fan-shaped carbide, An LD array optical waveguide which is formed so as to be guided to a tapered fiber satisfying NA value of half width of emergence NA of the carbide × (incidence diameter / emission diameter) ≦ NA specific to the fiber]. 2. An LD array optical waveguide for condensing laser light emitted from an LD array formed by arranging a plurality of laser diodes on a straight line and guiding the laser light to an optical fiber. The width of the incident end face corresponding to the width in the arrangement direction is 1/5 to 1/1 toward the output end face.
The laser beam emitted from the LD array is condensed by the fan-shaped carbide formed at the taper angle decreasing to 0,
Laser light emitted from a tapered fiber connected to the emission end face of the fan-shaped carbide and formed so as to have a high refractive index in the center direction is focused through a first condenser lens combining lenses having different focal length ratios. The condensed laser light is guided to an arbitrary position by an optical fiber formed so that the refractive index increases toward the center, and re-condensed through a second condenser lens combining lenses having different focal length ratios. An LD array optical waveguide characterized by being constituted. 3. The LD array optical waveguide according to claim 1, wherein a fiber lens is disposed between the LD array and the fan-shaped carbide. 4. An LD array optical waveguide for condensing laser light emitted from an LD array configured by arranging a plurality of laser diodes on a straight line and guiding the laser light to an optical fiber, wherein the emission end face of the LD array is provided. The laser diode emitted from each laser diode of the LD array is arranged on the LD array such that the laser light emitted from each laser diode intersects at a center point outside the emission end face of the trapezoidal carbide. An LD array optical waveguide characterized by being provided. 5. The LD array optical waveguide according to claim 4, wherein the trapezoidal carbide is formed of a lens material whose refractive index increases toward the end in the thickness direction.