JP2535930B2 - Grooving method for brittle members - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for grooving a brittle member, and more specifically, a method for grooving a brittle member such as a substrate of an optical integrated circuit with a required groove. The present invention relates to a method for processing a groove of a brittle member, which eliminates the occurrence of a gap in the connecting portion of the optical fiber with respect to the obtained groove and effectively suppresses the optical transmission loss.

2. Description of the Related Art With the recent development of optoelectronics, optical transmission systems tend to be widely used as alternatives to conventional telecommunication systems. This optical transmission system uses an optical fiber made of, for example, quartz or multi-component glass as a medium for transmitting information by light, and therefore is not affected by electromagnetic induction and has a large capacity of information transmission density. It has many advantages such as being obtained. In the above-mentioned optical transmission technology, optical information is exchanged between the optical waveguide and the optical fiber in the substrate of the optical integrated circuit in which the light emitting element, the waveguide, the light receiving element, etc. are integrated (light incidence / emission), For this reason, a technique for coupling an optical fiber to an optical integrated circuit substrate is generally practiced.

One of the methods for coupling an optical fiber to this optical integrated circuit board
As an example, a groove of the required depth is formed in an optical integrated circuit board made of glass or lithium niobate (LiNbO ₃ ) crystal, and the left end of the optical fiber is exposed in this groove, and a UV curable resin is used. Techniques for bonding are known. In this optical fiber coupling method, since the groove is formed in the optical integrated circuit substrate, there is an advantage that the optical fiber can be positioned with respect to the substrate with high accuracy. On the other hand, however, since the substrate is made of a highly brittle and difficult-to-cut material such as glass or lithium niobate, it is generally difficult to process the groove, and chipping such as cracking or chipping occurs during processing, resulting in defects. High rate,
In addition, there is a problem that a loss due to light dispersion between the tip of the optical fiber and the groove is large.

As a solution proposal for these problems, the applicant of the present invention invented "a method for grooving a brittle member" (Japanese Patent Application No. 61-2883).
No. 31) has been filed. The present invention is characterized in that a pyramidal tool having a pyramidal tip is fed in a horizontal direction while being rotated, and a groove having a V-shaped cross section is cut on the surface of the workpiece. The required groove can be formed on the optical integrated circuit board of the insulating member without chipping.

Problems to be Solved by the Invention As shown in FIG. 4, according to the invention of the above application,
A groove 12 having a V-shaped cross section can be formed on the surface of the substrate 10 to a required depth, and the optical waveguide 16 on the substrate 10 can be provided with the V-shaped groove 12 only by facing the tip of the optical fiber 14. The central axis of the optical fiber 14 can be positioned with high accuracy. However, in order to cut the V-shaped groove 12 while rotating the pyramid tool, the deepest part 12a of the V-shaped groove 12 corresponds to the tip angle of the pyramid tool used for machining, as can be seen from FIG. It is formed as an angled slope. Therefore, V-shaped groove
When the tip of the optical fiber 14 faces the 12
a The open end 16a of the optical waveguide 16 located above
A gap S is inevitably formed between the tip of 14 and the gap S causes a loss due to the dispersion of light, resulting in a problem of reducing the optical transmission efficiency.

OBJECT OF THE INVENTION The present invention has been proposed in view of the problems inherent in the “grooving method for brittle members” according to the above-mentioned application, and it is a proposal that should be solved in a suitable manner. An object of the present invention is to provide a means capable of realizing highly efficient optical transmission without loss due to light dispersion between the optical fiber and the optical waveguide when the optical fiber is coupled to the circuit board.

Means for Solving the Problems In order to overcome the above problems and achieve the intended purpose, the present invention provides a machining method for machining a groove along the surface of a brittle member while rotating a pyramidal tool. A groove is fed along the surface of the brittle member, and a groove having an end portion with a V-shaped cross section and an innermost portion inclined is machined on the surface, and then high energy is applied to the inclined end portion of the V-shaped groove. It is characterized by irradiating a beam to flatten the part in the direction perpendicular to the surface of the brittle member.

Effect According to the groove processing method of the present invention, the deepest end of the V-shaped groove in the optical integrated circuit board is flattened in the vertical direction so that the optical fiber and the optical waveguide are closely attached to each other. You can

EXAMPLES Next, a method for grooving a brittle member according to the present invention will be described with reference to the accompanying drawings with reference to preferred examples. The same members as those already described with reference to FIG. 4 are designated by the same reference numerals.

The optical integrated circuit board 10 made of a brittle member such as glass material or lithium niobate has the above-mentioned Japanese Patent Application No. 61-288331.
A groove 12 having a V-shaped cross section is formed by the method according to No. That is, on the surface of the optical integrated circuit board 10, the pyramidal tool made of cemented carbide is rotated and sent in the axial direction to perform cutting, and by repeating this cutting a plurality of times,
The groove 12 having a V-shaped cross section is machined in a good condition without any chipping. In this case, V-shaped groove 12
As shown in FIG. 1, a slanted surface and a curved surface having an angle corresponding to the tip angle of the pyramid tool are formed in the innermost portion 12a and its vicinity.

The optical integrated circuit board 10 is placed on a known XY table (not shown), and the board 10 can be moved in the X and Y directions in the plane coordinates by operating the table. To do. A processing head 20 of a high energy beam processing machine (not shown) is located above the moving area of the XY table. As the high energy beam processing machine, a CO ₂ gas laser processing machine is preferably used in the illustrated example, but the high energy beam emitted from the processing head 20 is a glass material or a crystal of lithium niobate. As long as it is possible to perform beam processing on highly difficult-to-cut materials, for example, plasma arc processing machine,
An electric discharge machine or the like can be selectively used.

Optical integrated circuit board with V-shaped groove 12 thus cut
At 10, a mask 18 made of a material capable of reflecting the high-energy beam, for example, an aluminum plate, is applied so that the V-shaped groove 12 can be covered with a mask. The mask 18 is provided with a notch 18a having a required shape, for example, a rectangular shape, and the position is preliminarily set so that the notch 18a is aligned with the innermost part 12a of the V-shaped groove 12. .

Then, the processing head 20 of the laser processing machine (not shown)
A CO ₂ laser is emitted vertically downward from the laser to irradiate the mask 18 of the optical integrated circuit substrate 10 with the laser beam. At the same time, the XY table described above is operated to move the substrate 10 in the X direction and the Y direction at a required timing. As a result, the laser beam relatively scans the mask 18, and the laser beam is reflected on the surface of the mask 18. Therefore, the optical integrated circuit board 10
The portion covered by the mask 18 is not processed at all. But the laser beam
When the portion of the rectangular cutout portion 18a opened in the above is scanned, the beam reaches the innermost portion 12a of the V-shaped groove 12, and the high energy causes the beam irradiation portion to be instantly evaporated. That is, the innermost part 12a of the V-shaped groove 12 formed of a slope having an angle corresponding to the tip angle of the pyramid tool is machined to have the opening shape of the notch 18a as shown in FIG. The processing conditions in this case are shown in Table 1 below.

When the groove processing is performed by the method according to this embodiment, as shown in FIG. 2, the vicinity of the end of the V-shaped groove 12 becomes a rectangular parallelepiped depending on the opening shape of the cutout portion 18a, and the innermost portion 12a thereof is the substrate 10. Is planarized in the direction perpendicular to the surface of the. When the tip of the optical fiber 14 is positioned in the V-shaped groove 12 of the optical integrated circuit substrate 10 processed in this way, the central axis of the optical fiber 14 is located in the optical waveguide on the substrate 10 due to the existence of the V-shaped groove 12. 16 is positioned with high precision. Moreover, the open end surface of the optical fiber 14 is
The innermost portion 1a, which is flattened in the vertical direction, is closely butted against the innermost portion 1a, so that no gap is formed between the optical fiber 14 and the optical waveguide 16. Therefore, it is possible to effectively suppress the loss of light dispersion and obtain high optical transmission efficiency.
The V-shaped groove 12 and the optical fiber 14 are adhered and solidified with, for example, an ultraviolet curable resin.

In the embodiment, a mask made of an aluminum plate is used.
Although the example using 18 has been described, the mask 18 may be made of another material such as gold (Au) or silver (AG) as long as it can reflect a high energy beam such as a laser beam. Further, the example in which the optical integrated circuit board 10 is placed on the XY table and the XY table is moved in the X direction and the Y direction with respect to the processing head 20 has been described. On the contrary, the optical integrated circuit board 10 is fixed. Alternatively, the beam processing may be performed by positioning the processing head 20 and moving the processing head 20 in the X and Y directions.

EFFECTS OF THE INVENTION As described above, according to the method for grooving a brittle member according to the present invention, a brittle member obtained by cutting a groove having a V-shaped cross section and an end having an inclined innermost portion is The slanted end can be flattened in a direction perpendicular to the surface of the brittle member. Therefore, if this method is applied to the groove processing of the substrate of the optical integrated circuit, it becomes possible to closely contact the open end face of the optical fiber to the deepest part which is flattened in the vertical direction. The loss of light dispersion between the optical waveguide and the optical waveguide is effectively suppressed, and high optical transmission efficiency can be obtained. Also, since the high energy beam has a small amount of heat input during beam processing, it is possible to suppress the heat effect at the processing site to an extremely small extent, and also to remove the residual stress caused by the mechanical cutting process with the pyramid tool. There are also possible additional effects. Further, the conventional advantage that the central axis of the optical fiber can be positioned with high accuracy in the optical waveguide on the substrate by simply exposing the optical fiber to the V-shaped groove formed on the surface of the substrate is inherited as it is. .

[Brief description of drawings]

FIG. 1 is an explanatory perspective view showing an embodiment of a processing state by a groove processing method for a brittle member according to the present invention, and FIG. 2 is an explanatory perspective view showing a state after performing the processing shown in FIG. 1, FIG. 3 is a vertical cross-sectional view showing a state in which an optical fiber is positioned in a groove portion of an optical integrated circuit board obtained by the method for forming a groove of a brittle member according to the present invention, and FIG. 4 is a groove processing according to the prior art. It is a longitudinal cross-sectional view showing a state in which an optical fiber is positioned in a groove portion of an optical integrated circuit substrate obtained by the method. 10 …… Substrate, 16 …… Optical waveguide 12 …… V-shaped groove, 16a …… Open end 12a …… Deepest part, 18 …… Mask 14 …… Optical fiber, 18a …… Notch 20 …… Processing head

Claims (3)

(57) [Claims] 1. A machining method for machining a groove along the surface of a brittle member, wherein a pyramidal tool is rotated and transversely fed along the surface of the brittle member to form a V-shaped cross section at the innermost portion. After cutting a groove having a slanted end portion on the surface, the slanted end portion of the V-shaped groove is irradiated with a high energy beam to flatten the portion in the direction perpendicular to the surface of the brittle member. A method for grooving a brittle member, characterized by: 2. The method for grooving a brittle member according to claim 1, wherein the brittle member is a substrate of an optical integrated circuit. 3. The method for grooving a brittle member according to claim 1, wherein the high energy beam is a laser beam.