JPH07140351A - Connector for optical fiber - Google Patents

Abstract

PURPOSE:To provide the optical fiber connector for a laser beam which does not generate thermal destruction by the clad mode of the laser beam of a high power. CONSTITUTION:A circular truncated cone-shaped prism having a front surface 8b smaller than the core diameter of an optical fiber 1 and a conical surface 8a of 45 deg. angle with the optical axis of the optical fiber 1 is arranged at the end of the optical fiber 1 by directing the conical surface 8a toward the optical fiber 1 side. The end of the optical fiber 1 is mounted via a core 6 within a connector body 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber connector for laser.

[0002]

2. Description of the Related Art A laser light source of high optical power, such as YA
In the optical fiber connector using the G laser light source, when the optical axis of the light source or the optical fiber of the emission side and the optical axis of the incident side do not match, the emitted light is incident on the clad and the optical fiber is thermally destroyed.

As a practical problem, heat is often generated during the adjustment of the optical axis to cause destruction.

In order to solve this problem, conventionally, as shown in FIG. 1, an air clad layer 2, an optical deflecting member 3 having a high refractive index n = 1.77 such as sapphire, and a copper-based metal connector body 4 (heat radiation) are used. Part) is provided, and the light beam 5 whose optical axis is being adjusted is the cladding 1
When incident on a, a structure is proposed in which the laser light traveling in the clad 1a is polarized by the light deflecting member 3 to the outside of the clad 1a and is radiated by the metal connector body 4 to prevent thermal destruction of the optical fiber 1. ing.

However, the connector shown in FIG. 1 has the following problems in use as well as in manufacture.

(1). When polishing the end face of an optical fiber during manufacturing, the fiber is supported in a cantilever shape, and it takes a long time to perform the work.

(2). When dust adheres to the end face of the optical fiber and the air clad part, it is not only difficult to remove, but also
If dust remains attached, heat is generated and the optical fiber is broken.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a connector which does not have the problems that the conventional connector shown in FIG. 1 has.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it has an upper surface smaller than the core shape of the optical fiber at the end of the optical fiber and an optical axis of the optical fiber. On the other hand, a truncated cone prism having a conical surface with an angle of 45 ° is arranged with the upper surface facing the optical fiber side.

[0010]

The harmful laser light without the prism is reflected by the prism toward the light source side, and only useful laser light is incident on the core of the optical fiber.

[0011]

2 shows an embodiment of the present invention, in which 1 is an optical fiber, 6 is a core attached to the end of the optical fiber 1, and 7 is a core.
Is a connector body, 8 is a truncated cone prism, 9 is a laser light source, and 10 is a lens.

The upper surface 8a (smaller surface) of the truncated cone prism 8 is smaller than the core diameter D of the optical fiber, and the conical surface 8a thereof has an angle of 45 ° with respect to the optical axis of the optical fiber 1 (manufactured). Error is allowed), and the conical surface 8a is arranged toward the optical fiber side.

FIG. 3 is an explanatory view of the action of the truncated cone prism 8. Now, considering only meridian rays incident on the prism at an angle θ with respect to the optical axis, the prism upper surface 8c (the larger surface) is directly entered. Of the light rays, the useful light ray 11 is incident on the core of the optical fiber 1.

On the other hand, a ray 12 which is reflected twice in the harmful ray
Is the upper surface 8 in the same direction as the incident light beam, that is, at an angle θ.
It is emitted to the c side. Further, the light reflected in the order of the lower conical surface 8a → the upper surface 8b → the upper conical surface 8a is the upper surface 8c at an angle of −θ.
It is emitted to the side.

The NA of an optical fiber often used in this field is 0.2, and the maximum value of θ is 10 degrees or less. θ is 1
Ordinary rays below 0 degrees (not limited to meridional rays)
We also confirm experimentally that it is similar to meridian rays. However, since the conical surface is a curved surface, in reality, even if straight-ahead light is incident, it will spread as light and return to the laser light source side. This is useful for laser stability and safety. Here, in order to satisfy the condition of total reflection of the prism at θ = 10 degrees, the refractive index of the prism must be 1.74 or more (a value larger than n of air).

As described above, in the optical fiber connector according to the present invention, the conical prism 8 prevents the harmful rays from entering the optical fiber 1 and prevents the optical fiber from being damaged by heating.

According to the structure of the present invention, the optical fiber 1 is held by the core 6 by polishing the end face of the optical fiber 1 before mounting the optical fiber 1 with the core 6 on the connector body 7. Therefore, the polishing work can be easily performed. Further, as shown in the figure, the truncated cone prism 8 is also used as a sealing piece, so that the problem of dust as in conventional products can be eliminated.

FIG. 4 shows another embodiment of the present invention, in which the light incident side, that is, the upper surface 11 of the truncated cone prism 11.
The lens effect is provided by using a as a spherical surface.

According to this structure, the focal point of the lens 10 can be separated from the prism 11, so that when the pulse laser is used, it is possible to prevent the focal point of the lens 10 from being located inside the prism. Damage to the frustoconical prism due to energy can be avoided.

As a material for the prisms 8 and 11, sapphire (n = 1.755 in case of entry = 1.06 μm) is preferable.

[0021]

According to the present invention, since the problem of thermal destruction due to the cladding mode is solved, the core 6 can be used as in the embodiment shown in FIGS. It becomes possible to employ a structure that is easy to polish and does not cause a problem due to dust adhesion, and it is possible to provide an excellent optical fiber connector practically used for laser processing or laser technology.

[Brief description of drawings]

FIG. 1 is a sectional view of a conventional optical fiber connector.

FIG. 2 is a sectional view of an embodiment of the present invention.

FIG. 3 is a diagram for explaining the operation of the embodiment of the present invention.

FIG. 4 is a sectional view of a different embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber 2 Air clad layer 3 Optical deflection member 4 Connector body 5 Light beam 6 Optical fiber 7 Connector body 8 Cone trapezoidal prism 9 Laser light source 10 Lens

Claims (2)

[Claims] 1. A frustoconical prism having an upper surface smaller than a core diameter of the optical fiber and having a conical surface having an angle of 45 ° with respect to the optical axis of the optical fiber at the end of the optical fiber. Optical fiber connector characterized by being arranged toward the side 2. The end portion of the optical fiber has an upper surface smaller than the core diameter of the optical fiber and has a diameter of 4 with respect to the optical axis of the optical fiber.
An optical fiber connector characterized in that a truncated cone prism having a conical surface with an angle of 5 ° is arranged with the upper surface facing the optical fiber side, and the ray incident side of the truncated cone prism is a spherical surface.