JP2018066771A - Coupling lens and laser optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser optical system and a coupling lens that have high productivity, relating to the laser optical system for coupling a laser beam emitted from a laser light source to an optical fiber by a coupling lens, and the coupling lens.SOLUTION: A coupling lens 5 comprises a body part 6 having a quadrangular prism shape, a first lens part 7 disposed on a first main surface in the body part 6, and a second lens part 8 disposed on a second main surface in the body part 6 facing back to the first main surface. A first side face 6c in the body part 6 has a flat mounting surface 9 orthogonal to the first main surface, and, defining a side face orthogonal to the first side face 6c in the body part 6 as a second side face 6d and defining a direction orthogonal to the second side face 6d as a first direction, a width W1 of the mounting surface 9 in the first direction is configured to be within a range of 50% to 80% of a width W of the body part 6 in the first direction.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a laser optical system and a coupling lens that couple a laser beam emitted from a laser light source to an optical fiber with a coupling lens.

  The laser optical system in the present disclosure indicates an optical system that is coupled to an optical fiber via a coupling lens output from a laser light source. The laser optical system includes a laser light source, a coupling lens, an optical fiber, and a base. The laser light source, the coupling lens, and the optical fiber are arranged on the base so that their optical axes coincide.

  Conventionally, a coupling lens used in such a laser optical system has been studied for a structure having a quadrangular outer shape in plan view in the optical axis direction. That is, in this coupling lens, lens portions are arranged on the main surface on the incident side and the main surface on the emission side of the main body portion, and the outer shape of the main body portion is a quadrangle in a plan view when viewed from the optical axis direction. One side surface is a mounting surface connected to the base.

  For example, Patent Documents 1 to 3 are known as prior art document information related to the invention of this application.

JP 2007-86221 A JP 2008-203418 A JP 2008-297146 A

  When assembling such a laser optical system, for example, a laser light source and an optical fiber are arranged at predetermined positions on a base. Next, a coupling lens is disposed between the laser light source and the optical fiber. The coupling lens is positioned while confirming the coupling efficiency for converging the light beam emitted from the laser light source onto the optical fiber. In actual positioning of the coupling lens, an adhesive is applied to the mounting area of the base, and then positioning is performed by the mounter, and the coupling lens is connected on the base. Note that the adhesive expands and contracts due to environmental conditions such as temperature and humidity, leading to a decrease in coupling efficiency in the laser optical system. Therefore, it is necessary to reduce the adhesive as much as possible in order to reduce the influence of the shape change of the adhesive.

  On the other hand, when the coupling lens is mounted, if the adhesive does not sufficiently wrap around the mounting surface, the coupling lens is likely to fall over the base. Accordingly, when the amount of the adhesive is reduced, the coupling lens must be supported by the mounter while the coupling lens is positioned on the base and the adhesive is sufficiently wrapped around the mounting surface. That is, there is a problem that the assembly time of the laser optical system becomes long.

  The present disclosure aims to solve such problems and increase the productivity of laser optical systems.

One aspect of the coupling lens in the present disclosure includes a quadrangular prism-shaped main body portion, a first lens portion disposed on the first main surface of the main body portion, and a second back facing the first main surface of the main body portion. A second lens portion disposed on the main surface of the main body portion, the first side surface of the main body portion has a flat mounting surface orthogonal to the first main surface, and the first side surface of the main body portion, The width of the mounting surface in the first direction is 50% of the width of the main body in the first direction, with the side surface orthogonal to the second side surface 6d and the direction orthogonal to the second side surface 6d as the first direction. To 80%.

  An aspect of the laser optical system according to the present disclosure includes a base, a laser light source disposed on the base, and the base on the optical axis of the light beam emitted from the laser light source. A coupling lens and an optical fiber disposed on the base and on the optical axis, wherein the coupling lens is a quadrangular columnar main body and a first main surface disposed on the first main surface of the main body. One lens portion and a second lens portion disposed on a second main surface facing away from the first main surface of the main body portion, and the first side surface of the main body portion is the first main surface A flat mounting surface orthogonal to the surface, the side surface orthogonal to the first side surface in the main body portion is the second side surface, the direction orthogonal to the second side surface is the first direction, in the first direction The width of the mounting surface is set in the range of 50% to 80% of the width of the main body in the first direction.

  With this configuration, the productivity of the laser optical system can be increased.

FIG. 1 is a schematic diagram illustrating a laser optical system according to an embodiment of the present disclosure. FIG. 2 is a front view of the coupling lens constituting the laser optical system according to the embodiment of the present disclosure. FIG. 3 is a bottom view of the coupling lens constituting the laser optical system according to the embodiment of the present disclosure. FIG. 4 is a schematic diagram illustrating a method for manufacturing a coupled lens according to an embodiment of the present disclosure.

  Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below shows a preferred specific example of the present disclosure. Accordingly, the shapes, materials, components, arrangement of components, connection forms, and the like shown in the following embodiments are merely examples, and are not intended to limit the present disclosure. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims showing the highest concept of the present invention are described as optional constituent elements.

  FIG. 1 shows a laser optical system 100 that couples a light beam 2 emitted from a laser light source 1 to an optical fiber 3. The laser optical system 100 is used in, for example, an optical communication system. The laser optical system 100 is configured by arranging a laser light source 1, a coupling lens 5, and an optical fiber 3 on a base 4.

  The base 4 is composed of a silicon substrate. A portion of the base 4 where the laser light source 1 is disposed is provided with a light source base 4a protruding upward. The height of the light source base 4a is set so that the optical axis 2a coincides with the laser light source 1 and the coupling lens 5 in the height direction. A portion of the base 4 where the optical fiber 3 is disposed is provided with an optical fiber pedestal 4b protruding upward. A V-shaped groove (not shown) is provided on the upper portion of the optical fiber pedestal 4b. By arranging the optical fiber 3 in the V-shaped groove, the optical fiber 3 is positioned at the height of the optical axis 2a.

The laser light source 1 can use a laser diode. For example, the laser optical system 10
When 0 is used for a transmission system in an optical communication system, the wavelength of light emitted from the laser light source 1 is set to 1310 nm. When the laser optical system 100 is used in a transmission system in an optical communication system, the wavelength of light emitted from the laser light source 1 is set to 1550 nm.

  The coupling lens 5 faces the rectangular columnar main body 6, the first lens portion 7 disposed on the first main surface 6 a facing the laser light source 1 in the main body portion 6, and the optical fiber 3 in the main body portion 6. And a second lens portion 8 disposed on the second main surface 6b. FIG. 2 shows a front view of the coupling lens 5 as seen from the optical axis direction. The main body 6 has a first main surface 6a, a second main surface 6b, and first to fourth side surfaces 6c to 6f. In the main body 6, the first main surface 6a and the second main surface 6b face away from each other. The first side surface 6c has a flat mounting surface 9 as shown in FIG. FIG. 3 is a bottom view of the coupling lens 5. The mounting surface 9 is an area bonded to the base 4. The second side surface 6d is orthogonal to the first side surface 6c. The third side surface 6e is orthogonal to the first side surface 6c and faces away from the second side surface 6d. The fourth side surface 6f faces away from the first side surface 6c.

  Moreover, the broken line 7a in FIG. 2 shows the boundary of the 1st lens part 7 and the 1st main surface 6a. A solid line 8a indicates a boundary between the second lens unit 8 and the second main surface 6b. These boundaries have a circular shape, and the diameter of the circle indicating this boundary is called the machining diameter. The main body 6 in the coupling lens 5 has a quadrangular prism shape. However, the surface-to-surface connection portion of the main body 6 is connected by a curved surface. In addition, the connection part of the surface in the main-body part 6 corresponds to the part corresponding to the ridgeline of the 1st main surface 6a and the 1st side surface 6c, or the ridgeline of the 1st side surface 6c and the 2nd side surface 6d, for example. Indicates the part. The expression “square prism shape” in the present disclosure indicates a shape in which the ridge line portion in the main body portion 6 is a curved surface. Moreover, the 1st main surface 6a and the 2nd main surface 6b are flat surfaces except the curved surface of a ridgeline part. The size of the main body 6 is, for example, a height H of 1 mm, a width W of 1 mm, and a thickness D of 0.47 mm. Further, the processing diameter A on the first main surface 6a is 0.6 mm, and the processing diameter B on the second main surface 6b is 0.74 mm. The width W1 in the optical axis direction on the mounting surface 9 is 0.65 mm, and the width W2 in the direction orthogonal to the optical axis 2a is 0.38 mm. The direction orthogonal to the optical axis 2a is the same as the direction orthogonal to the second side surface 6d. As shown in FIG. 3, in the coupling lens 5, the protrusion amount of the second lens portion 8 protruding from the main body portion 6 is larger than the protrusion amount of the first lens portion 7.

  The reason why the ridge line portion of the main body portion 6 is a curved surface is due to the manufacturing method of the coupling lens 5. Next, a method for manufacturing the coupling lens 5 will be described.

  FIG. 4 is a schematic diagram showing a molding process of the coupling lens 5. The press molding machine has a lower mold 20, an upper mold 21, and a body mold 22. The upper surface of the lower mold 20 has a molding surface 20 a for transferring the second main surface 6 b of the coupling lens 5. The upper surface of the upper mold 21 has a molding surface for transferring the first main surface 6 a of the coupling lens 5. The body mold 22 has a rectangular through hole. The lower mold 20 is inserted and fixed from the lower side of the body mold 22. The upper mold 21 is slidably inserted from the upper end of the body mold 22.

  In press molding of the coupling lens 5, first, a glass material 30 is disposed in a space formed by the lower mold 20 and the barrel mold 22. The glass material 30 is made of optical glass processed into a spherical shape. Next, the upper mold 21 is inserted from the upper end of the body mold 22. In this state, the glass material 30 is heated to raise the temperature. After the glass material 30 has been heated to a moldable temperature range equal to or higher than the heat point transfer temperature, the upper mold 21 is slid downward to deform the glass material 30. When the distance between the upper mold 21 and the lower mold 20 reaches a desired value, the sliding of the upper mold 21 is stopped. The glass material 30 is cooled while maintaining the position of the upper mold 21. When the glass material 30 is cooled to a temperature at which it can be taken out from the press molding machine, the upper mold 21 is slid upward to take out the glass material 30 from the press molding machine. The press-molded glass material 30 means the coupling lens 5.

  In such a press molding process, it is important to set the volume of the glass material 30 smaller than the volume of the press molding space. The press molding space means a space surrounded by the upper mold 21, the lower mold 20 and the body mold 22 when the distance between the upper mold 21 and the lower mold 20 reaches a desired value. When the volume of the glass material 30 is larger than the volume of the press molding space, the surplus portion of the glass material 30 enters the gap between the upper mold 21 and the barrel mold 22 and between the lower mold 20 and the barrel mold 22. The entry of the surplus portion causes the sliding of the upper mold 21 and the mold opening failure. Therefore, the volume of the glass material 30 is set to be smaller than the volume of the press forming space in advance so that an excessive portion of the glass material 30 is not generated including processing variations. Thus, since the volume of the glass material 30 is set to be smaller than the volume of the press molding space, the outer peripheral portion of the upper mold 21 in contact with the barrel mold 22 and the outer peripheral portion of the lower mold 20 in contact with the barrel mold 22 are described. The glass material 30 does not wrap around. As a result, the ridge line portion of the main body 6 in the press-molded coupling lens 5 has a curved surface shape. The curved surface of the ridge line portion of the main body 6 is a free curved surface on which the molding surface is not transferred. Further, the proportion of the curved surface of the ridge line portion can be adjusted by the volume of the glass material 30.

  In this coupling lens 5, the width of the mounting surface 9 in the direction orthogonal to the second side surface 6d is not less than 50% and not more than 80% of the width of the main body 6 in the direction orthogonal to the second side surface 6d. Set to range. By defining the width of the mounting surface 9 in this way, the productivity of the laser optical system 100 can be increased.

  That is, the area of the mounting surface 9 is reduced by reducing the width of the mounting surface 9 in the coupling lens 5. Since the area of the mounting surface 9 is reduced, the time required for the adhesive to wrap around the base 4 is shortened. Therefore, the time for supporting the coupling lens 5 by the mounter is shortened and the productivity is increased. If the width of the mounting surface 9 is 80% or more of the width of the main body 6, the effect of reducing the area of the mounting surface 9 is not sufficient. If the width of the mounting surface 9 is less than 50% of the width of the main body 6, the area of the mounting surface 9 becomes too small and the stability when the coupling lens 5 is bonded to the base 4 is deteriorated.

  In the coupled lens 5, the processing diameter B of the second lens portion 8 is larger than the processing diameter A of the first lens portion 7. Based on this configuration, the upper limit of the processing diameter B is limited by the width W1 of the mounting surface 9. The processing diameter B is an element that affects the durability of the lower mold 20 in the press molding machine. A bowl-shaped recess corresponding to the second lens portion 8 is formed on the molding surface 20 a of the lower mold 20. Therefore, when the machining diameter B is large, the distance from the opening end of the recess to the outer periphery of the upper mold 21 is small. As a result, the durability of the upper mold 21 is lowered. On the other hand, according to the present disclosure, as described above, the width W1 of the mounting surface 9 is limited to 80% or less and 50% or more of the width W of the main body 6. Therefore, since the width W1 of the mounting surface 9 is limited by the machining diameter B, the mold durability can be ensured. When the processing diameter B of the second lens portion 8 is smaller than the processing diameter A of the first lens portion 7, the processing diameter A of the first lens portion 7 may be made smaller than the width W <b> 1 of the mounting surface 9. When the processing diameter A of the first lens portion 7 and the processing diameter B of the second lens portion 8 are equal, both the processing diameter A of the first lens portion 7 and the processing diameter B of the second lens portion 8 are both. Both may be made smaller than the width W1 of the mounting surface 9.

  The coupling lens and the laser optical system according to the present disclosure are useful in a small optical communication system application such as a QFSP (Quad Small Form-factor Pluggable).

DESCRIPTION OF SYMBOLS 1 Laser light source 2a Optical axis 3 Optical fiber 4 Base 5 Coupling lens 6 Main-body part 6a 1st main surface 6b 2nd main surface 6c 1st side surface 6d 2nd side surface 7 1st lens part 8 2nd Lens part 9 Mounting surface 100 Laser optical system A, B Processing diameter W Body part width W1 Mounting surface width

Claims (4)

A quadrangular prism main body,
A first lens portion disposed on a first main surface of the main body portion;
A second lens portion disposed on the second main surface facing away from the first main surface in the main body portion, and
The first side surface of the main body has a flat mounting surface orthogonal to the first main surface,
A side surface orthogonal to the first side surface in the main body portion is a second side surface,
The direction perpendicular to the second side surface is the first direction,
The width of the mounting surface in the first direction is set in a range of 50% to 80% of the width of the main body in the first direction.
Combined lens. The processing diameter of the second lens portion is larger than the processing diameter of the first lens,
A width of the mounting surface in the first direction is smaller than a processing diameter of the second lens portion;
The coupling lens according to claim 1. The base,
A laser light source disposed on the base;
A coupling lens disposed on the base and on an optical axis of a light beam emitted from the laser light source;
An optical fiber disposed on the optical base and on the optical axis;
With
The coupling lens is
A quadrangular prism main body,
A first lens portion disposed on a first main surface of the main body portion;
A second lens portion disposed on the second main surface facing away from the first main surface in the main body portion, and
The first side surface of the main body has a flat mounting surface orthogonal to the first main surface,
A side surface orthogonal to the first side surface in the main body portion is a second side surface,
The direction perpendicular to the second side surface is the first direction,
The width of the mounting surface in the first direction is set in a range of 50% to 80% of the width of the main body in the first direction.
Laser optical system. The processing diameter of the second lens portion is larger than the processing diameter of the processing diameter of the first lens,
A width of the mounting surface in the first direction is smaller than a processing diameter of the second lens portion;
The laser optical system according to claim 3.

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