JP2002350687A - Light output decrease preventive structure for optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decrease preventive structure for light output which can prevent a decrease tendency of the light output resulting from the elliptical sectional shape of a light beam. SOLUTION: A direction wherein an optical fiber 9 held by an optical fiber holding member 11 is apt to shift in position is matched with an axial direction wherein the tolerance of the position shift is large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for preventing a decrease in optical output which can be applied to a semiconductor laser module having, for example, a semiconductor laser light source and an optical fiber for extracting the emitted light, and more particularly to a light beam having an elliptical cross section. Focusing on the shape of the optical fiber, the present invention relates to an invention that defines the relationship with the direction in which the optical fiber is likely to be misaligned.

[0002]

2. Description of the Related Art A laser beam B emitted from a semiconductor laser light source generally has an elliptical cross section as shown in FIG. The shape of the semiconductor laser light source 101 for irradiating the laser beam B having such an elliptical cross section has a rectangular flat plate shape as shown in FIG. 6 (b). Laser light source 1
01 was mounted in a horizontal state as shown in the figure.

In such a horizontal state, the laser beam B
Are defined such that the major axis extends in the horizontal direction (shown as the x direction in FIG. 6A) and the minor axis extends in the vertical direction (shown as the y direction in FIG. 6A).

FIG. 6C is a graph schematically showing the relationship between the magnitude of the optical output from the optical fiber and the amount of displacement of the optical fiber. In the drawing, the solid line indicates the dependence of the laser beam B in the y direction shown in FIG. 6A, and the broken line indicates the x direction dependence. As is clear from the graph, in the y direction of the laser beam B, the allowable width of the optical fiber positional deviation amount in the allowable range of the optical output is narrow, and is wide in the x direction. In other words, it can be seen that a slight displacement of the optical fiber in the horizontal direction does not significantly affect the light output, but a slight displacement in the vertical direction has a great effect on the light output.

On the other hand, as shown in FIG. 7, the optical fiber holding member 105 of the semiconductor laser module 103 holds the optical fiber 109 by an inverted U-shaped or U-shaped holding action portion 107 located at the center. It often adopts a configuration of pinching.

Further, two optical fiber holding members 105 are arranged in series with respect to the optical axis direction of the optical fiber 109, and the optical fiber holding member 105 remote from the light source is connected to the optical fiber 109. In the case where the vertical position shift occurs, the position can be adjusted in the vertical direction so that the optical fiber holding member 105 provided near the semiconductor laser light source 101 can be rotated around the fixing welding point as a fulcrum. . Therefore, in such an inverted U-shaped optical fiber holding member 105, the optical fiber 109 is unlikely to be displaced in the left-right direction, but relatively easily displaced in the up-down direction.

[0007]

Therefore, when the optical fiber 109 is held by the inverted U-shaped optical fiber holding member 105 in view of the shape of the output intensity distribution of the laser beam B, the upper and lower sides of the optical fiber 109 are When the displacement in the direction is accompanied by a large change in light output, the position of the optical fiber 109 has to be frequently adjusted.

[0008] Such a phenomenon is caused by the optical fiber 109.
A connection portion between an input / output unit of an optical waveguide device such as an optical switch, an optical modulator, and an optical amplifier provided between the optical fiber 109 and the optical fiber 109;
This also occurs at a connection portion between the optical fiber 109 and a lens system provided for the purpose of shaping, focusing, and the like of the laser beam B irradiated from No. 1.

It is an object of the present invention to provide a structure for preventing a decrease in optical output of an optical fiber, which can prevent a decrease in optical output due to a light beam such as a laser beam having the above-mentioned oblong cross section. Make it an issue. The term “prevention of optical output of the optical fiber from decreasing” in this specification refers to preventing the optical output of the optical fiber from decreasing with time after assembling, and reducing the optical output due to displacement due to welding or the like during assembling. This includes at least prevention.

[0010]

The present inventor has conducted intensive studies to solve the above-mentioned problems, and as a result, the tendency of the light output to decrease due to the cross-sectional shape of the light beam has been reduced between the major axis direction of the light beam and the member. The present inventor has found that it can be dealt with by appropriately adjusting the direction of the generated positional shift, and arrived at the present invention.

That is, in the structure for preventing a decrease in the optical output of an optical fiber according to the present invention, the axial direction in which the optical fiber held by the optical fiber holding member is easily displaced coincides with the axial direction in which the tolerance for the positional deviation is large. It is characterized by the following. Further, the optical output reduction prevention structure of the optical fiber of the present invention is such that the direction in which the optical fiber held by the optical fiber holding member is easily displaced coincides with the major axis direction of the light beam having an elliptical cross section. It is a feature. Further, a light source pedestal for supporting a rectangular plate-shaped semiconductor laser light source is provided, and the semiconductor laser light source is attached vertically to the light source pedestal such that the long axis of the laser beam is in the vertical direction, The optical fiber holding member may sandwich left and right ends of the optical fiber, and a space may be formed vertically.

The present invention can also be applied to a case where a light beam having an elliptical cross section is emitted from an optical waveguide device. The present invention can also be applied to a case where a light beam having an elliptical cross section is incident on an input end of an optical fiber via a lens system provided between the light source and the optical fiber.

A fiber lens processed into a lens shape may be formed at the input end of the optical fiber. Further, the fiber lens may be a wedge-shaped lens which shapes a light beam having an elliptical cross section into a light beam having a circular cross section and has a high optical coupling effect.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing an embodiment in which the optical output reduction structure of an optical fiber according to the present invention is applied between a semiconductor laser light source and an input end of an optical fiber in a semiconductor laser module, and FIG. FIG. 4 is a vertical sectional front view taken along the line A and an explanatory diagram showing a procedure for mounting the semiconductor laser light source.

In FIG. 1, reference numeral 1 denotes a semiconductor laser module. The semiconductor laser module 1 includes a pedestal 3, and a semiconductor laser light source 7 is provided on an upper surface of the pedestal 3 via a light source pedestal 5. The light source pedestal 5
Is fixed to the pedestal 3, and the semiconductor laser light source 7 is fixed to the light source pedestal 5 in a characteristic posture described later.

A clip type optical fiber holding member 11 formed by bending or bending a metal plate is provided on the upper surface of the base 3 to hold the optical fiber 9 as an example. In the embodiment shown in FIG. 1, two optical fiber holding members 11 are connected in series in the optical axis direction of the optical fiber 9.
, But only one optical fiber holding member 11
It is also possible to adopt a configuration in which the optical fiber 9 is held.

An optical fiber holding member 11 is formed at its center with a holding action portion 13 curved in an inverted U-shape. The optical fiber 9 is held in the holding action portion 13 so that the optical fiber 9 can be positioned. It has become.

The optical fiber holding member 11 remote from the semiconductor laser light source 7 is formed with an elastic bending portion 15. By appropriately deforming the elastic action bending portion 15, the optical fiber 9 is moved into the space 17 formed above it.
The vertical position can be adjusted within the range of the concave portion 19 formed on the upper surface of the pedestal 3.

The optical fiber 9 is composed of a fiber line 21 located at the center and a metal ferrule 2 formed around the fiber line 21.
The laser beam B incident from the input end 25 is received by the core in the fiber line 21, and the laser beam B is reflected by the optical fiber 9 while reflecting the laser beam B at the interface between the core and the clad. It has a structure that progresses inside. At the input end 25 of the optical fiber 9, a fiber lens 27 processed into a lens shape is formed, and by its operation, the laser beam B is converged in the core of the optical fiber 9 to increase the input efficiency to the laser beam B. Can be.

As shown in FIG. 3A, the fiber lens 27 is processed into a cone shape whose tip is bulged in a convex shape toward the semiconductor laser light source 7, and as shown in FIG. What is processed into a wedge shape or a minus driver shape can be applied. By the way, if the wedge-shaped fiber lens 27 shown in FIG. 3B is used, a laser beam B having an elliptical cross section can be shaped into a laser beam B having a circular cross section, and a high optical coupling effect can be obtained. When the optical fiber 9 having such a wedge-shaped fiber lens 27 is attached to the optical fiber holding member 11, the major axis direction of the laser beam B having an elliptical cross section irradiated from the semiconductor laser light source 7 is Align so that it matches the long direction of the wedge.

Next, the structure 29 for preventing the optical output of the optical fiber from dropping according to the present invention applied to the semiconductor laser module 1 will be described. The light output lowering prevention structure 29 is configured to match the direction in which the position of the optical fiber 9 is likely to shift with the major axis direction of the laser beam B having an elliptical cross section.
An object of the present invention is to minimize a decrease in optical output caused by a displacement of an optical fiber. This can be achieved by arranging and fixing the semiconductor laser light source 7 in the form of a rectangular flat plate to the light source pedestal 5 vertically as shown in FIGS.

A mounting mount 31 having an insulating portion is provided between the semiconductor laser light source 7 and the light source pedestal 5. The light source pedestal 5 made of a metal material and the semiconductor laser light source are provided by the mounting mount 31. 7 is prevented from contacting with electrical contacts formed on the side surface.

The mounting mount 31 has a section L as shown in the figure.
The bottom surface of the semiconductor laser light source 7 is joined to one surface of the surface on which the mounting portion 33 is formed, and the other end surface of the mounting portion 33 and the semiconductor laser light source 7 The gap 35 is formed between the side surface and the side surface, so that the insulation between them is maintained.

When the semiconductor laser light source 7 is mounted on the light source base 5 using the mounting mount 31, first, FIG.
As shown in (a), the bottom surface of the semiconductor laser light source 7 is joined to one end surface of the mounting portion 33 such that a gap 35 is formed with the thick support portion 37 of the mounting mount 31 being down. . Next, as shown in FIG. 2B, the mounting mount 31 is rotated by 90 ° counterclockwise to
The thin base portion 39 of FIG.
The mounting mount 31 is mounted on the upper surface of the light source base 5 as shown in FIG.

The mounting mount 31 has a concave shape as shown in FIG.
As shown in FIG. 7, a combination of two L-shaped plate members back to back can be used. Further, as shown in FIG. 4C, by forming the mounting portion 41 on the light source base 5, the function of the mounting mount 31 can be imparted to the light source base 5.

The structure for preventing a decrease in the optical output of an optical fiber according to the present invention is based on the above-described structure. However, the structure is not limited to this structure, and the structure can be partially changed as described below. is there.

For example, when the positional deviation of the optical fiber 9 becomes large in the left-right direction due to the structure of the optical fiber holding member,
It is also possible to mount the semiconductor laser light source 7 on the light source base 5 in a horizontal state.

The structure 29 for preventing a decrease in light output according to the present invention.
Is formed between the optical fiber 9 and the optical waveguide device 43 such as an optical switch, an optical modulator, and an optical amplifier provided between the optical fibers 9 connected in series as shown in FIG. An optical transport path, a lens system including one or a plurality of lenses 45 provided between the semiconductor laser light source 7 and the optical fiber 9 in the semiconductor laser module 1 as shown in FIG. It is also possible to apply to an optical transport path formed between the laser light source 7 and the optical fiber 9.

[0029]

According to the first aspect of the present invention, even when the optical fiber is slightly displaced on the optical fiber holding member due to a heat cycle or the like, since the displaced direction is the axial direction having a large tolerance, the optical output can be reduced. Is small, and a stable light output can be obtained.

According to the second aspect of the present invention, even when the optical fiber is slightly displaced on the optical fiber holding member due to a heat cycle or the like, the displaced direction is the major axis direction of the elliptical cross section of the light beam having a large positional tolerance. Therefore, the influence on the light output is small, and a stable light output can be obtained.

According to the third aspect of the present invention, the vertical direction in which the optical fiber is likely to be displaced coincides with the major axis direction of the elliptical cross section of the laser beam. Can be effectively prevented.

According to the fourth aspect of the present invention, it is possible to effectively prevent a decrease in the optical output between the optical fiber device and the optical fiber that outputs the light beam having the elliptical cross section.

According to the fifth aspect of the present invention, even when laser light enters the optical fiber via the lens system, a decrease in optical output can be effectively prevented as described above.

According to the sixth aspect of the present invention, the light beam can be converged in the core of the optical fiber to increase the efficiency of input to the optical fiber. When the positional deviation tolerance is small, the effect of suppressing the decrease in the optical output is more remarkable.

According to the seventh aspect of the present invention, a light beam having an elliptical cross section is shaped into a light beam having a circular cross section, and a high optical coupling effect can be obtained. On the other hand, due to the asymmetric lens effect, the difference between the positional deviation tolerances in the two orthogonal axial directions is further increased, and the effect of suppressing the decrease in the light output according to the present invention becomes even more remarkable.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a semiconductor laser module in which a structure for preventing a decrease in optical output of the present invention is applied between a semiconductor laser light source and an input end of an optical fiber.

FIG. 2 is a longitudinal sectional front view taken along line AA in FIG. 1 and an explanatory view showing a procedure for mounting a semiconductor laser light source.

FIG. 3 is a perspective view showing two embodiments of a fiber lens provided at an input end of an optical fiber.

FIG. 4 is a longitudinal sectional front view showing other various embodiments in which the configuration of the mounting mount is different.

FIG. 5 is a schematic diagram showing an outline of another two types of optical waveguide paths.

FIG. 6 is a plan view showing a cross-sectional shape of a laser beam, a perspective view showing an outline of a semiconductor laser light source, and a graph schematically showing the relationship between the magnitude of light output from an optical fiber and the amount of displacement of the optical fiber. .

FIG. 7 is a perspective view showing a conventional semiconductor laser module having no structure for preventing a decrease in optical output.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 semiconductor laser module 3 pedestal 5 light source pedestal 7 semiconductor laser light source 9 optical fiber 11 optical fiber holding member 13 holding action section 15 elastic action bending section 17 space 19 recessed section 21 fiber line 23 metal ferrule 25 input end 27 fiber lens 29 light Output lowering prevention structure 31 Mounting mount 33 Mounting section 35 Air gap 37 Support section 39 Base section 41 Mounting section 43 Optical waveguide device 45 Lens B Laser beam

Claims (7)

[Claims] 1. A structure for preventing a decrease in optical output of an optical fiber, wherein an axial direction in which the optical fiber held by the optical fiber holding member is easily displaced coincides with an axial direction having a large tolerance for the positional deviation. 2. The optical fiber according to claim 1, wherein the direction in which the optical fiber held by the optical fiber holding member is easily displaced coincides with the major axis direction of the light beam having an elliptical cross section. Construction. 3. The light source pedestal according to claim 1 or 2, further comprising a light source pedestal for supporting a semiconductor laser light source having a rectangular flat plate shape, wherein the semiconductor laser light source is positioned with respect to the light source pedestal such that the long axis of the laser beam is directed vertically. Wherein the optical fiber holding member sandwiches the left and right ends of the optical fiber, and a space is formed vertically above and below the optical fiber. 4. An optical fiber according to claim 1, wherein the optical coupling with the optical fiber is performed between an optical waveguide device having a light distribution having an elliptical cross section and an optical waveguide. Structure to prevent optical output reduction of optical fiber. 5. The optical fiber according to claim 2, wherein the light beam having the elliptical cross section is incident on an input end of the optical fiber via a lens system provided between the light source and the optical fiber. Light output reduction prevention structure. 6. A structure for preventing a decrease in light output of an optical fiber according to claim 1, wherein a fiber lens processed into a lens shape is formed at an input end of the optical fiber. 7. The fiber lens according to claim 6, wherein the fiber lens is a wedge-shaped lens that shapes a light beam having an elliptical cross-section into a light beam having a circular cross-section and has a high optical coupling effect. Structure to prevent optical output reduction of optical fiber.