JP2501119B2 - Adhesive fixing method for optical components - Google Patents

Description

The present invention relates to an adhesive fixing method for an optical component that is a component of an optical device, and an adhesive fixing method for an optical component that does not deform the optical component or apply stress to the optical component due to the fixing. A method for adhering and fixing optical components that are opaque to ultraviolet rays for curing an ultraviolet curable resin with an ultraviolet curable resin for the purpose of interposing a transparent block between the optical components. By irradiating ultraviolet rays toward the inside, the ultraviolet curable resin interposed between the optical component and the transparent block is cured.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bonding and fixing an optical component which is a component of an optical device. Here, an optical component is a component of an optical isolator, an optical switch, or other optical device, and is deformed when or after mutual fixing regardless of whether light is guided to the component. It covers all parts that are required to be done and stress-free.

When constructing an optical transmission system, an optical transmitter / receiver,
In addition to the optical transmission line, various optical devices such as an optical isolator, an optical switch and an optical multiplexer / demultiplexer are required. An optical device is designed to achieve a desired function by fixing a large number of optical components to each other. Generally, the positional relationship between the optical components directly affects the characteristics of the optical device. There is a demand for a method of fixing an optical component that does not cause deformation due to the above. Further, in an optical device utilizing polarized waves, a stress applied to a lens or the like causes a birefringence phenomenon to make the characteristics of the optical device unstable, so that a fixing method in which stress is generated as little as possible is required.

2. Description of the Related Art A conventional fixing method for an optical component will be described with reference to FIG.
In the method shown in FIG. 3A, the optical components 4 to be fixed to each other are
The thermosetting adhesive 43 is interposed between the optical components 41 and 42.
After the position adjustment is performed, the whole is kept at a high temperature to solidify the thermosetting adhesive 43, and the optical components are mutually fixed. In addition, in the method shown in FIG.
Metal layers 53, 54 such as Au are formed on the surfaces of 1, 52, respectively, and the solder 55 interposed between the metal layers 53, 54 is melted at high temperature and then cooled and solidified to form an optical component. We are fixing each other.

Problems to be Solved by the Invention With the conventional fixing method, the temperature at which the thermosetting adhesive cures is about 60 ° C., and since the temperature at which the solder solidifies is 100 ° C. or higher, the optical components to be fixed When the coefficient of thermal expansion is different, distortion occurs near the fixed part when the optical components are cooled to room temperature where the optical device is normally used, and the positional relationship between the adjusted optical components is different from that immediately after adjustment. Or stress acts on the optical components. For example, if the optical components whose optical axes have been adjusted are displaced, the loss characteristic of the optical device deteriorates. Further, for example, when stress acts on a magneto-optic crystal such as YIG in an optical isolator, birefringence occurs in the crystal,
There is a problem that the extinction ratio of the optical isolator deteriorates.

In order to avoid these problems, in recent years, a method of fixing optical parts using an ultraviolet curable resin (UV resin) as an adhesive has been implemented. On the other hand, there is a drawback that this method can be used only for fixing transparent optical components. For example, the above YIG, birefringent crystal rutile (T
Since the iO ₂ ) crystal is opaque to ultraviolet rays for curing the ultraviolet curable resin, the conventional fixing method using the ultraviolet curable resin cannot be adopted for these.

The present invention was created in view of such circumstances,
It is an object of the present invention to provide an adhesive fixing method for an optical component that is opaque to ultraviolet rays for curing an ultraviolet curable resin, in which the fixing does not deform the optical component or apply stress to the optical component.

Means for Solving the Problems FIG. 1 is a principle diagram of the present invention.

This method involves interposing a transparent block 3 between the optical components 1 and 2 when the optical components 1 and 2 opaque to ultraviolet rays for curing the ultraviolet curable resin are bonded and fixed by the ultraviolet curable resin. By irradiating the inside of the transparent block 3 with ultraviolet rays 4, the ultraviolet curable resin 5 interposed between the optical components 1 and 2 and the transparent block 3 is cured.

Here, the transparent block 3 is a member transparent to ultraviolet rays for curing the ultraviolet curable resin.

When ultraviolet rays are irradiated toward the inside of the transparent block interposed between the optical components, the ultraviolet ray propagates inside the transparent block because the transparent block is transparent to the ultraviolet ray. At this time, the ultraviolet rays introduced into the transparent block are specularly or diffusely reflected at the interface between the transparent block and the ultraviolet curable resin or the interface between the ultraviolet curable resin and the optical component, and reach the entire transparent block. Therefore, the ultraviolet curable resin is rapidly cured by being irradiated with ultraviolet rays. As described above, according to the present invention, since it is possible to fix an opaque optical component at room temperature, there is no possibility that the optical component is deformed or stress is applied.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a front view of an optical isolator showing an embodiment of the present invention. This optical isolator is configured by arranging a polarizer 12, a YIG crystal 13, and a polarizer 14 as an optical component in this order on an optical axis OA set parallel to a substrate 11 as an optical component. Then, the YIG crystal 13 is fixed to the substrate 11 via the transparent block 15 by the method of the present invention. As the material of the transparent block 15, for example, quartz glass can be used. For convenience of explanation of the operation described later, the forward direction of the optical isolator on the optical axis OA (from left to right in the figure) is the z-axis direction, perpendicular to the z-axis and parallel to the substrate 11 from the back side to the front side of the paper. The penetrating direction is the x-axis direction, and the direction perpendicular to the x-axis and the zx-axis and going from the bottom to the top in the figure is the y-axis direction.

FIG. 3 is a wavelength characteristic diagram of the YIG crystal 13, in which the vertical axis represents the transmittance (%) and the horizontal axis represents the wavelength λ (μm) of light. 1.3 ~ 1.55μ used in general optical transmission system
The YIG crystal 13 is transparent for light having a wavelength in this range because it exhibits a high transmittance at a wavelength of m. But,
It exhibits a transmittance of 1% or less for ultraviolet rays (for example, a wavelength of 0.2 to 0.3 μm) for curing the ultraviolet curable resin, and the YIG crystal 13 is opaque to such ultraviolet rays. Therefore, if the substrate 11 is also opaque, the YIG
It is not possible to irradiate the ultraviolet curable resin with ultraviolet rays through the crystal 13 or the substrate 11, and thus, as in this example, YIG
By interposing the transparent block 15 between the crystal 13 and the substrate 11, fixing with an ultraviolet curable resin becomes possible for the first time.

FIG. 4 is a diagram for explaining the operation of the optical isolator shown in FIG. 2, in which the polarization direction in the xy plane is shown. In FIG. 2, for example, when collimated light from a semiconductor laser is incident on the polarizer 12 in the z-axis direction, the polarization plane of the light emitted from the polarizer 12 is y as shown in FIG. 4 (a). It will be parallel to the axis. This polarized light is YI
When the light is incident on the G crystal 13, the polarization plane of the emitted light forms an angle of 45 ° with respect to the y-axis or the x-axis, as shown in FIG. Then, the polarization plane of the polarizer 14 is
Since the light is emitted from the YIG crystal 13 in the forward direction through the polarizer 14, it is introduced into the optical transmission line such as an optical fiber because it is configured to be the same as that shown in FIG. .

On the other hand, in the reflected feedback light reflected by the end face of the optical fiber and returned to the optical isolator, the original linear polarization state is not generally preserved, but the light transmitted through the polarizer 14 in the −z axis direction is Only the polarized state shown in FIG. 7B is obtained, and this light is rotated by 45 ° by the YIG crystal 13 to become linearly polarized light parallel to the x-axis direction as shown in FIG. Therefore, this polarized light cannot pass through the polarizer 12, and the reflected feedback light is prevented from affecting the light source.

By the way, when stress is applied to the YIG crystal 13 and birefringence occurs, the light transmitted through the YIG crystal 13 in the −z-axis direction does not become completely direct polarized light, and as shown in FIG. In addition, it becomes elliptically polarized light having a polarization component parallel to the y-axis direction. When a polarization component parallel to the y-axis direction is generated, this polarization component passes through the polarizer 12 and reaches the light source, so that the function as an optical isolator deteriorates, that is, the extinction ratio deteriorates. In this embodiment, since the YIG crystal 13 can be fixed at room temperature, there is no risk of adding stress that causes birefringence to the YIG crystal 13 in the normal operating temperature range of the optical isolator, and a high extinction ratio It becomes possible to provide an optical isolator.

FIG. 5 is a plan view (a) and a front view (b) of an optical switch showing another embodiment of the present invention. Reference numeral 21 is a fiber collimator for converting the light emitted from the end surface of the optical fiber 22 into a parallel light beam.
Insert the optical fiber 22 into the ferrule 23 and secure it
A ball lens 24 is inserted into and fixed to a sleeve 25 into which a ball lens 24 is press-fitted, for example. 26 and 27 are fiber collimators 2
This is a fiber collimator with the same configuration as 1. Reference numeral 28 denotes an optical path switching unit, which is a movable prism that can reciprocate in the direction of the arrow in the figure.
A guide 30 that slidably supports 29 and this movable prism 29.
It consists of and. And the fiber collimator 2
When fixing 1, 26, 27 and the optical path switching unit 28 to the substrate 31, a transparent block 32 is interposed between the fiber collimators 21, 26, 27 and the substrate 31, and a transparent block 33 is provided between the optical path switching unit 28 and the substrate 31. By irradiating the inside of the transparent blocks 32 and 33 with ultraviolet rays so as to intervene, the ultraviolet curable resin (not shown) adhered to each fixed portion is cured.

The operation of this optical switch will be described. The prism 29 is the fifth
When in the state shown in Fig. (A), the fiber collimator
The light from 21 passes through the transmitting surface 29a of the prism 29, is reflected by the reflecting surfaces 29b and 29c, passes through the transmitting surface 29d, and enters the fiber collimator 27. When the prism 29 is moved downward in the figure, the light from the fiber collimator 21 is moved to the prism.
Since the light is not incident on 29, this light is directly incident on the fiber collimator 26. The optical path is switched in this way.

In the optical switch having the structure as shown in FIG. 5, it is necessary to fix the optical components with each other while adjusting the positional relationship of the optical components with high accuracy. Fixing can be performed in an extremely short time as compared with the case where a thermosetting adhesive is used, and workability is improved.
Further, since the fixing is carried out at room temperature as in the previous embodiment, there is no possibility that the fixing portion is greatly deformed due to the temperature change, and high optical coupling efficiency can be maintained for a long period of time.

EFFECTS OF THE INVENTION As described in detail above, according to the present invention, an optical component that is opaque to ultraviolet rays for curing the ultraviolet curable resin can be bonded and fixed at room temperature by the ultraviolet curable resin. Therefore, there is an effect that there is no possibility that the optical component is deformed by the fixing and the optical component is stressed.

[Brief description of drawings]

1 is a principle view of the present invention, FIG. 2 is a front view of an optical isolator showing an embodiment of the present invention, FIG. 3 is a YIG wavelength characteristic diagram, and FIG. 4 is a view of the optical isolator shown in FIG. FIG. 5 is a plan view (a) and a front view (b) of an optical switch showing another embodiment of the present invention, and FIG. 6 is a view for explaining a conventional technique. It is a figure. 1,2 …… Optical parts, 3,15,32,33 …… Transparent block, 5…
... UV curable resin.

Claims (1)

(57) [Claims] 1. A method for adhering and fixing optical components which are opaque to ultraviolet rays for curing an ultraviolet curable resin with an ultraviolet curable resin, wherein a transparent block (3) is provided between the optical components (1, 2). ), And irradiating the inside of the transparent block (3) with ultraviolet rays (4), the ultraviolet curable resin (between the optical components (1, 2) and the transparent block (3) ( 5) A method for adhering and fixing an optical component, characterized in that it is cured.