JP2513599B2 - Method for manufacturing optical waveguide substrate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an optical waveguide substrate used in an optical communication system, and more particularly to a method for finishing an optical fiber bonding surface of the optical waveguide substrate into a smooth surface.

The optical communication system is spreading in a wide field as an optimum communication system in the information society. However, many of the parts and devices that make up the optical communication systems that have been provided so far cannot be mass-produced because they require high accuracy and reliability, and this is a cause of hindering the cost reduction of optical communication systems. ing.

Therefore, in order to reduce the cost of optical communication systems by mass production, we have improved the form of parts and devices so that mass production can be performed while maintaining high accuracy and reliability, and the development of mass-production manufacturing technology. Is desired.

[Conventional technology]

FIG. 2 is a perspective view showing a method of connecting an optical waveguide and an optical fiber on an optical waveguide substrate, and FIG. 3 is a process diagram showing a conventional example of a method of mirror-finishing an optical fiber joint surface.

In the figure, an optical waveguide substrate 1 is a substrate 2 made of glass.
And the optical waveguides 3 and 4 formed on the surface of the substrate 2, and the optical waveguides 3 and 4 and the optical fiber 5
The optical fiber 5 is bonded to the optical fiber joint surface 6 for connection with the optical fiber 5. However, in order to reduce the optical loss at the joint between the optical waveguides 3 and 4 and the optical fiber 5, the optical fiber joint surface 6 needs to be mirror-finished and placed.

The optical waveguide substrate 1 is processed and finished by the process shown in FIG. That is, a plurality of optical waveguide substrates 1 formed on the same substrate are cut in a cutting step 10 to form individual optical waveguide substrates 1. However, as shown in FIG. 2, the optical fiber joint surface 6 is on the cut surface of the substrate, and work such as grinding 11, sanding 12, and polishing 13 is performed to finish the cut surface into a mirror surface.

In the grinding step 11, the cut surface is roughened using a diamond grindstone. Grinding process 11 is roughly divided into rough grinding, intermediate grinding, and precision grinding.A grindstone with a particle size of # 100 is used for rough grinding, a grindstone with a particle size of # 200 is used for intermediate grinding, and precision grinding is used for precision grinding. A grindstone with a grain size of # 400 is used.

The surface of the optical waveguide substrate 1 finished in the grinding step 11 has insufficient surface roughness and large irregularities remain. Therefore, before sanding, a fine sand surface is formed in the sanding step 12. That is, lapping is performed using a cast iron dish and fine abrasive sand with a grain size of about 800 to 1500.

However, the fine sandy surface is also opaque due to the fine irregularities on the surface. In the polishing step 13, a plate with pitch or felt and a fine abrasive such as red iron oxide (iron oxide) or cerium oxide are used to transparently polish and finish it into a mirror surface.

[Problems to be solved by the invention]

In the conventional method for finishing the optical fiber joint surface to be a mirror surface, grinding, sanding and polishing are required three times, and there is a problem that mass productivity of the optical waveguide substrate is significantly impaired.

[Means for solving problems]

The above problem is that a low melting point layer made of a material that is transparent and has a refractive index substantially equal to that of the optical waveguide and a melting point lower than that of the optical waveguide substrate is formed on the optical fiber bonding surface of the rough-finished optical waveguide substrate. This is solved by the method for manufacturing an optical waveguide substrate according to the present invention, in which the optical fiber joint surface is finished into a smooth surface by heating and melting.

[Action]

By heating and melting the low melting point layer formed on the optical fiber joint surface, the irregularities remaining on the optical fiber joint surface are filled, and the surface after cooling and solidification becomes a mirror surface, so sanding or polishing work Is unnecessary and mass production is promoted.

〔Example〕

An embodiment of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a process drawing showing an embodiment of the manufacturing method according to the present invention.

In the figure, a plurality of optical waveguide substrates 1 formed on the same substrate are cut in a cutting step 10 to form individual optical waveguide substrates 1, and in the next low melting point layer forming step 14, sputtering, vapor deposition, vapor deposition, A low melting point layer made of a material which is transparent and has a refractive index substantially equal to that of the optical waveguide and a melting point lower than that of the optical waveguide substrate is formed on the optical fiber bonding surface by using a film forming means such as a phase growth method. For example, glass (melting point 61
In the optical waveguide substrate using 5 ℃, lead borate (melting point 350
To 400 ° C.) to form the low melting point layer.

Then, in the heating and melting step 15, the low melting point layer is heated and melted at a temperature lower than the melting point of the optical waveguide substrate.

By heating and melting the low melting point layer formed on the optical fiber joint surface, the irregularities remaining on the optical fiber joint surface are filled, and the surface after cooling and solidification becomes a mirror surface, so sanding or polishing work Is unnecessary and mass production is promoted.

〔The invention's effect〕

As described above, according to the present invention, it is possible to provide a method of manufacturing an optical waveguide substrate that promotes mass production and contributes to cost reduction.

[Brief description of drawings]

FIG. 1 is a process diagram showing an embodiment of a method for manufacturing an optical waveguide substrate according to the present invention, FIG. 2 is a perspective view showing a method of connecting an optical waveguide and an optical fiber on the optical waveguide substrate, and FIG. FIG. 6 is a process diagram showing a conventional example of a method for mirror-finishing a fiber joint surface. In the figure, 1 is an optical waveguide substrate, 2 is a substrate, 3 and 4 are optical waveguides, 5 is an optical fiber, 6 is an optical fiber joint surface, 10 is a cutting step, 11
Is a grinding step, 12 is a sanding step, 13 is a polishing step, 14 is a low melting point layer forming step, and 15 is a heating and melting step.

 ─────────────────────────────────────────────────── (72) Inventor Ippei Sawaki 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Fujitsu Limited Fujitsu Limited (72) Keiichi Nakajima 1015 Kamedotachu, Nakahara-ku, Kawasaki City, Fujitsu Limited

Claims (1)

(57) [Claims] 1. In the manufacture of an optical waveguide substrate comprising at least a substrate and an optical waveguide formed on the substrate, an optical fiber bonding surface of a rough-finished optical waveguide substrate is transparent and has a refractive index of A low melting point layer made of a material having a melting point substantially equal to that of the waveguide and lower than that of the optical waveguide substrate is formed, and the low melting point layer is melted by heating, whereby the optical fiber bonding surface is finished into a smooth surface. Method for manufacturing optical waveguide substrate.