JP2018072499A - Coupling lens and laser optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly productive laser optical system and a highly productive coupling lens which make a laser beam emitted from a laser light source be coupled to an optical fiber by a coupling lens.SOLUTION: A coupling lens 5 includes: a body part 6 in the shape of a square pole; a first lens part 7 on a first main surface 6a of the body part 6; a second lens part 8 on a second main surface 6b, the second main surface being opposed to the first main surface 6a of the body part 6, the body part 6 having a first side surface 6c, and the first side surface 6c having a flat mounted surface 9 perpendicular to the first main surface 6a. In a plane view of the first side surface 6c, the distance from the mounted surface 9 to the first main surface 6a is made different from the distance from the mounted surface 9 to the second main surface 6b.SELECTED DRAWING: Figure 3

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 in a plan view of the first side surface The distance from the mounting surface to the first main surface is different from the distance from the mounting surface to the second main surface.

  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, and in the plan view of the first side, the distance from the mounting surface to the first main surface is different from the distance from the mounting surface to the second main surface Yes.

  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 side view of the coupling lens constituting the laser optical system according to the embodiment of the present disclosure. FIG. 5 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 FIGS. FIG. 3 is a bottom view of the coupling lens 5. FIG. 4 is a side 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 0.46 mm. Further, the processing diameter A on the first main surface 6a is 0.49 mm, and the processing diameter B on the second main surface 6b is 0.72 mm. The width W1 in the optical axis direction on the mounting surface 9 is 0.55 mm, and the width W2 in the direction orthogonal to the optical axis 2a is 0.37 mm. The direction orthogonal to the optical axis 2a is the same as the direction orthogonal to the second side surface 6d. The distance W3 from the mounting surface 9 to the second main surface 6b is 0.03 mm. A distance W4 from the mounting surface 9 to the first main surface 6a is 0.06 mm. As shown in FIGS. 3 and 4, 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. 5 is a schematic view 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 the coupling lens 5, the distance W4 from the mounting surface 9 to the first main surface 6a and the distance W3 from the mounting surface 9 to the second main surface 6b are different in a plan view with respect to the first side surface 1a. It is Thus, the productivity of the laser optical system 100 can be increased by decentering the position of the mounting surface 9 with respect to the optical axis direction.

  That is, as shown in FIG. 4, the radius R1 of the curved surface located between the first main surface 6a and the first side surface 6c varies depending on the distance between the mounting surface 9 and the first main surface. Similarly, the radius R2 of the curved surface located between the second main surface 6b and the first side surface 6c varies depending on the distance between the mounting surface 9 and the second main surface 6b. That is, since the mounting surface 9 of the coupling lens 5 is decentered toward the second main surface 6b, the radius R2 is reduced and the radius R1 is increased. Therefore, the center of gravity G of the coupling lens 5 is eccentric to the second main surface side 6b. Further, the mounting surface 9 has a distance W3 to the second main surface 6b smaller than a distance W4 to the first main surface 6a. Therefore, as shown in FIG. 3, the center S of the mounting surface 9 is eccentric to the second main surface 6b side rather than the middle N between the first main surface 6a and the second main surface 6b.

  That is, by making the distance W4 from the mounting surface 9 to the first main surface 6a different from the distance W3 from the mounting surface 9 to the second main surface 6b, the center of gravity G of the coupling lens 5 and the mounting are viewed in plan view. The distance P from the center S of the surface 9 can be adjusted. As a result, it becomes difficult to fall down when the coupling lens 5 is mounted on the base 4. Therefore, since the time for supporting the coupling lens 5 by the mounter is shortened, the productivity of the laser optical system 100 is improved.

  When the volume of the second lens portion 8 protruding from the main body portion 6 is smaller than the volume of the first lens portion 7, the distance W4 from the mounting portion 9 to the first main surface 6a is set as the mounting portion. What is necessary is just to make it smaller than the distance W3 from 9 to the 2nd main surface 6b, and to decenter the mounting surface 9 to the 1st main surface 6a side.

  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 7 1st lens part 8 2nd lens part 9 Mounting surface 100 Laser optical system

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,
In plan view of the first side surface, the distance from the mounting surface to the first main surface is different from the distance from the mounting surface to the second main surface.
Combined lens. When the volume of the first lens part is larger than the volume of the second lens,
The distance from the mounting surface to the first main surface is smaller than the distance from the mounting surface to the second main surface,
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,
In plan view of the first side surface, the distance from the mounting surface to the first main surface is different from the distance from the mounting surface to the second main surface.
Laser optical system. When the volume of the first lens part is larger than the volume of the second lens,
The distance from the mounting surface to the first main surface is smaller than the distance from the mounting surface to the second main surface,
The laser optical system according to claim 3.

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