JPH0250110A - Optical element module - Google Patents

Abstract

PURPOSE:To obtain good adhering state without increasing the stress of a transparent plate contact part and to prevent returning light from being generated by applying a reflection preventive film on one surface of a transparent plate and then applying the tip of a ferrule to the surface of the thin transparent plate where the reflection preventive film is not applied. CONSTITUTION:The thin transparent plate 3 which has a plane or curved surface covered with the reflection preventive film and has a <=0.4 ratio of the thickness to the diameter (or width) is fixed under the ferrule insertion hole 4 of the housing 1 so that the surface where the reflection preventive film is not applied faces the entrance side of the ferrule insertion hole 4. Then the plate is deformed in conformity with the shape of the tip of the ferrule mounted on the housing. Therefore, even when the transparent plate 3 is incorporated slantingly, the tip of an in-ferrule fiber 6 is positioned in the contact part area between the transparent late 3 and ferrule 5 and no space is formed. Consequently, the transparent plate is adhered to the ferrule surface excellently and a stable light output is obtained without generating reflected light from the tip of the fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical element module that stably optically couples a light emitting element and an optical fiber.

(Prior Art) A communication system using optical fiber requires an optical element module that efficiently couples the light emitted from one light emitting element to the optical fiber. Conventionally, in this type of device, the light emitted from the light emitting element An optical system using a lens is widely used as a method to introduce the light into an optical fiber.
This is because this focused light can be introduced into the optical fiber relatively easily. An example of this type of device is a coupling device shown in FIG. 4, in which a light emitting element 9 is seated on a heat sink 11 protruding from the upper surface of a stem 7 via a submount 10. A cap 12 with a lens 8 attached thereto is welded to the stem 7. Light emitted from the light emitting element 9 is condensed by the lens 8, passes through the transparent plate 3, and is focused on the surface of the transparent plate. It has a connecting structure. As shown in FIG. 5, a ferrule 5 in which a fiber 6 is embedded is inserted into the ferrule introduction hole 4, and the transparent plate 3 is pressed. This suppression is the force of a spring attached to the ferrule end. After the light emitted from the laser passes through the lenses,
Although it enters the transparent plate, there is an anti-reflection film on the surface, and at the tip of the ferrule, the transparent plate and the tip of the ferrule are in close contact, making the structure so that no reflected light is generated.

[Problem to be solved by the invention]

In the above conventional structure, the light emitted from the light emitting element passes through the ball lens and the transparent plate and is taken into the fiber in the ferrule. is a spherical surface.

The ferrule is pressed against the transparent plate by spring force. The spring force is 2-3 kg. For this pressing force of 2 to 3 kg, the contact portion is a circular area with a radius of 0.2 nm. The stress at this time becomes large, exceeding 100 MPa.

When a transparent plate is incorporated, it often varies, such as being incorporated from a perpendicular position to an inclined position relative to the ferrule.

For example, when a transparent plate is installed at an angle of inclination of 0.2°, the contact area is shifted from the fiber position at the center of the ferrule, creating a space between the transparent plate and the ferrule, where the reflected light occurs. If this reflected light returns and enters the light emitting element, there is a problem that the oscillation state is disturbed and the light output fluctuates, and if the pressing force is increased to widen the contact area, the contact stress increases and there is a risk of cracking. . In addition, when the radius of curvature is increased, contact occurs over a wide range, but adhesion is reduced, gaps are likely to occur, and there is a problem in that return light is generated.

An object of the present invention is to provide a module that can achieve a state of good adhesion without increasing the stress at the contact portion of the transparent plate and does not generate return light.

[Means to solve the problem]

The above object is achieved by applying a thin transparent plate coated with an anti-reflection film on one side with the ferrule tip to the side without the anti-reflection film. That is, by pressing the glass plate and the ferrule tip, the glass plate and the ferrule tip are elastically deformed to follow the ferrule end face, so that adhesion can be obtained over a wide range. The transparent glass plate is preferably quartz glass with curvature on both sides, and it is further desirable that the refractive index of the transparent plate and the fiber core match.

[Effect]

When the tip of the ferrule having a curved surface is pressed against the transparent plate, the transparent plate elastically deforms to follow the curved surface of the ferrule. Elastic deformation increases the contact area over a wide range. In addition, the stress generated due to contact over a wide range will not be concentrated locally and become high.

Therefore, even if the transparent plate is installed at an angle, the tip of the fiber in the ferrule will be located within the contact area between the transparent plate and the ferrule, and no space will be formed. Therefore, stable optical output can be obtained from the tip of the fiber without any reflected light.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2.

<Example 1> In FIG. 1, the transparent plate 3 is a circular plate made of quartz glass, having a radius of curvature of 60 nm, and having a diameter of 3 m and a thickness of 0.5 nm, the lower surface of which is coated with an antireflection film.

The transparent plate 3 is held by a holding member 2 which is threaded around the periphery so as not to fall off. The holding member is made of Kovar material with a low coefficient of thermal expansion, and a through hole with a diameter of 2fffi is provided in the center through which light emitted from the light emitting element passes.

FIG. 2 shows a case where the ferrule 5 is inserted.

The radius of curvature of the ferrule tip is 60 m+. The fiber in the ferrule 5 is a quartz fiber with a diameter of 125 μm. The ferrule 5 receives a spring force of 2 from the other end of the ferrule.
Pressed by ~3kg. Due to this pressing, the transparent plate 3 is elastically deformed into the same shape as the tip end shape of the ferrule 5 and is brought into close contact with the transparent plate 3. The transparent plate used was quartz glass whose refractive index matched that of the quartz fiber, but it may also be made of plastic such as polycarbonate or epoxy resin.

The curved surface of the transparent plate 3 can also be installed so as to be concave with respect to the convex surface of the ferrule 5.

<Example 2> A flat transparent plate with a flat surface is used as the transparent plate 3, as shown in FIG.
The bottom surface) is coated with an anti-reflection film.

Although the above embodiment is an example of a light emitting module with a built-in light emitting element, it can also be applied to a light receiving module that receives light sent through a fiber.By attaching a transparent plate to the end of the fiber in the light receiving module, light that returns to the light emitting element can be applied. can be resolved. Furthermore, the present invention can also be applied to branch waveguides and switches with built-in fibers.

〔Effect of the invention〕

In the present invention, the transparent plate and the ferrule are brought into contact with the ferrule tip pressed against the relatively thin transparent plate. Since the transparent plate is elastically deformed following the ferrule surface shape, the transparent plate is in close contact with the ferrule surface. Due to this elastic deformation, the area of the contact portion is expanded several times more than in the conventional case. For this reason, the installation of the transparent plate has the effect of increasing the tolerance for variations in tilt. Since no gap is formed between the transparent plate and the ferrule tip surface, and since the refractive indexes of the transparent plate and the fiber within the ferrule are approximately equal, no reflected return light is generated at the interface between the two.

From the above, according to the present invention, the light emitted from the light emitting element is focused by the lens, enters the transparent plate without being reflected on the antireflection film surface, and is also reflected at the contact interface between the transparent plate and the fiber. This has the effect of being smoothly introduced into the fiber without causing any damage.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an optical element module according to an embodiment of the present invention, FIGS. 2 and 3 are cross-sectional views showing an example of a cross-section of the main part of FIG. A sectional view of the module, FIG. 5 is a sectional view of the main part of FIG. 4. DESCRIPTION OF SYMBOLS 1... Housing, 2... Holding member, 3... Transparent plate, 5... Ferrule 6... Fiber. Leaf Diagram 4--One person Ruley Nakairi JL Fuji layer χ Diagram Concave 7-11 Stem

Claims (1)

[Claims] 1. A disc-shaped stem, a light emitting element seated via a submount on a heat sink protruding from the stem,
A lens attached to a cap is opposed to the light-emitting cord, the cap is fixed to the stem, and a pipe is fixed by resistance welding to the upper circumference of the stem, and the light collected by the lens is fixed to the light emitting cord. The optical element module receives the light with a ferrule attached to a housing and fixes the contact part of the housing by welding. A thin transparent plate having a ratio of 0.4 or less is fixed to the lower part of the ferrule insertion hole of the housing with the surface without an anti-reflection film facing toward the entrance of the ferrule insertion hole, and the plate is shaped so as to match the shape of the tip of the ferrule installed in the housing. An optical element module characterized by being deformed by.