JP2000081512A - Etalon filter and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ultrathin etalon filter with high machining accuracy and high production yield by polishing one principal surface of a quartz substrate by mechanical machining and the other principal surface by etching and then forming dielectric films on both polished principal surfaces of the substrate. SOLUTION: A substrate 1 is obtained by mechanically polishing the both surfaces of a synthetic quartz substrate 1. The one surface of the substrate 1 is adhered with an acid-resistant adhesive or wax 7 to a large substrate such as synthetic quartz having several mm or more thickness and good parallelism to obtain a laminated substrate 11. The laminated substrate 11 is dipped in a fluorine-based etching liquid 9 in an etching tank 8 to wet etch the one surface of the substrate 1 to obtain a thin plate having specified thickness (about several ten μm). Then the substrate 1 is peeled from the large substrate 4, and only the substrate 1 satisfying the finish ratings of thickness and parallelism is selected. Then a dielectric material 6 such as alumina is vapor deposited on both surfaces of the substrate 1 to form reflection films 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-thin etalon filter and a method for manufacturing the same, and more particularly to a method for supplying an ultra-thin and inexpensive etalon filter substrate by combining a synthetic quartz substrate with mechanical polishing and wet etching. The present invention relates to an ultra-thin etalon filter and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, due to the remarkable spread of mobile communication and personal computer communication, the amount of data to be handled has become enormous and high speed has been demanded. In a data communication network, these plural kinds of data are used. 2. Description of the Related Art Wavelength multiplexing optical communication technology for converting light into light and transmitting the converted light using an optical fiber has become common. When wavelength multiplexing is performed in this manner, it is necessary to flatten the transmission band by adjusting the gain of the optical fiber amplifier that amplifies the optical signal in accordance with the interval between the optical signals and the number of multiplexed signals. Fabry-Perot -Etalon filter using resonance
In general, the in-band gain is equalized by combining a plurality of.

In this etalon filter, a synthetic quartz plate is processed into an ultra-thin substrate having a thickness of about several tens of μm, and reflecting films are adhered on both surfaces thereof to reflect the passing light, thereby converting an optical signal into a standing wave. In this case, the pass band is restricted to enable wavelength multiplexing of a plurality of optical signals, thereby facilitating optical transmission within a predetermined band. However, the basic characteristics of this filter are greatly affected by the optical characteristics determined by the thickness and the parallelism of the ultra-thin substrate. Control is required.

FIG. 2 is a view showing steps in an example of a conventional ultra-thin etalon filter and a method of manufacturing the same.
As shown in the figure, this manufacturing method includes the following steps. (1) A substrate 1 is prepared by mechanically polishing both sides of a synthetic quartz substrate 1. (2) A laminated substrate 10 in which one surface of the substrate 1 is attached to the large substrate 4 using an adhesive is produced. (3) The other surface of the substrate 1 on the laminated substrate 10 is mechanically polished and processed into a thin plate. (4) Only the substrate 1 that satisfies the final specification value is selected. (5) The reflective films 3 are deposited on both surfaces of the substrate 1. Hereinafter, the details of this manufacturing method will be described.

In the step (1), the substrate 1 is mirror-polished on both sides simultaneously or alternately one by one, and the thickness and the parallelism are measured using a micrometer for directly measuring the polished surface or an interference fringe of light projected on the polished surface. While measuring the thickness (about 50-100μ)
Although the substrate 1 has a thickness of about m), machining to such a thickness is technically established, and a sufficiently high processing quality can be obtained. In (2), a laminated substrate 10 is formed by attaching one surface of the substrate 1 to a large substrate 4 made of synthetic quartz or the like having a thickness of several mm or more and having good parallelism with an adhesive 5 (3) Fixing the laminated substrate 10 to a polishing apparatus. Then, one surface of the substrate 1 is mechanically polished. Check the thickness and parallelism on the way, and determine the thickness (approx.
The processing is repeated until the substrate 1 becomes the thin plate of m), and the substrate 1 is separated from the large substrate 4. Next, (4) both sides of the substrate 1 are measured, and only the substrate 1 that satisfies the final specification values in both thickness and parallelism is selected. (5) Dielectric material 6 such as alumina is deposited on both sides of the substrate 1. Thus, the ultra-thin etalon filter 2 is completed.

[0006]

However, in the conventional etalon filter and the manufacturing method thereof as described above, the bonding accuracy when the synthetic quartz substrate is bonded to the large-sized substrate has a flatness of the polished surface and a parallelism. Has a significant effect. For example, if the quartz substrate 1 is fixed non-parallel to the large-sized substrate 4 as shown in FIG. 3A, the left side in the figure is polished so as to be reduced, and as shown in FIG.
When the adhesive 5 is uneven, there is a problem that polishing is not uniform and unevenness is generated on the polished surface. Therefore, a technique has been proposed in which a quartz substrate which has been mechanically polished to a predetermined thickness is wet-etched to obtain a thin plate having a desired thickness. However, if the edge of the substrate is fixed with a jig in order to hold the quartz substrate in the etching solution, the portion covered by the jig is not etched and the desired thickness cannot be obtained. There is a problem that must be. In addition, there is also a problem in that the thinned substrate is cracked or chipped by the water flow generated by stirring the etchant, thereby lowering the yield.
SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems related to the conventional etalon filter and the method for manufacturing the same as described above, and provides an etalon filter and a method for manufacturing the etalon filter that can easily manufacture an ultrathin plate. The purpose is to:

[0007]

In order to achieve the above-mentioned object, according to the present invention, one main surface is machined, and the other main surface is provided on both main surfaces of a quartz substrate polished by etching. A method for manufacturing an etalon filter comprising a body film and a dielectric thin film on both surfaces of a quartz substrate having a predetermined thickness, wherein both surfaces of the quartz substrate are mechanically polished and polished. Is adhered and fixed to a large substrate, wet etching is performed together with the large substrate to obtain the predetermined thickness, and after the quartz substrate is separated from the large substrate, a dielectric film is deposited on both surfaces of the quartz substrate. Things.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments. FIG. 1 is a diagram showing steps in an ultra-thin etalon filter and a method of manufacturing the same according to the present invention. The same components as those in FIG. 2 are denoted by the same reference numerals. As shown in the figure, this manufacturing method includes the following steps. (1) Obtain a substrate 1 in which both surfaces of the synthetic quartz substrate 1 are mechanically polished. (2) A laminated substrate 11 is formed by attaching one surface of the substrate 1 to the large substrate 4 using an acid-resistant adhesive or wax 7. (3) The laminated substrate 11 is put into the etching tank 8 and immersed in an etching etchant (hereinafter, referred to as “etchant”) 9.
A predetermined amount of wet etching is performed on the other surface of the substrate to be processed to a desired thickness. (4) Only the substrate 1 that satisfies the final specification value is selected. (5) The reflective films 3 are deposited on both surfaces of the substrate 1. Hereinafter, the manufacturing method of the illustrated embodiment will be described in detail.

In FIG. 1, the step (1) of forming the substrate 1 by mechanical polishing is the same as the step (1) of the conventional example of FIG. At this time, the thickness and the parallelism of the substrate 1 are measured, and the substrate 1 for finishing to a thin plate of the final specification value is obtained.
Is used to determine the amount of etching. (2)
Then, one surface of the substrate 1 is attached to a large-sized substrate 4 such as synthetic quartz having a thickness of several mm or more and having good parallelism with an acid-resistant adhesive or wax 7.
To form a laminated substrate 11, and (3) the laminated substrate 11
Is immersed in a fluorine-based etching etchant (hereinafter referred to as an etchant) 9 in an etching tank 8 to wet-etch one surface of the substrate 1 to form a thin plate having a predetermined thickness (about several tens μm). Then, the laminated substrate 11 is taken out of the etching tank 8, and the substrate 1 is separated from the large substrate 4. At this time, the etching amount for processing the substrate 1 into a thin plate is determined based on the thickness and the etching rate measured in (1) with respect to the final specification value, and the concentration, temperature, and time of the etchant 9 are accurately determined. This is achieved by controlling At this time, the etchant 9 is agitated so that the concentration of the etchant near the substrate 1 is always made uniform. Next, (4) both sides of the substrate 1 are measured, and only the substrate 1 that satisfies the final specification values in both thickness and parallelism is selected. (5) Dielectric material 6 such as alumina is deposited on both sides of the substrate 1. Thus, the ultra-thin etalon filter 2 is completed.

[0010]

According to the etalon filter and the method of manufacturing the same of the present invention, the workability is remarkably improved since the primary substrate 1 whose both surfaces are mechanically polished is attached to the large substrate 4 and only one surface is wet-etched. . The amount of etching can be accurately grasped by controlling the concentration, temperature, and time of the etchant 9. Even when the quartz substrate is attached to a large-sized substrate, even if the substrate is inclined or the adhesive 7 is not evenly coated, the etching amount can be reduced. Since the surface is uniformly removed, the quartz substrate can be thinned while maintaining flatness and parallelism. Although the wet etching causes a decrease in the light transmittance of the substrate 1 and a decrease in the parallelism, it has almost no effect on the basic characteristics of the etalon filter, and has an extremely high processing accuracy and a high yield rate. The etalon filter 2 can be manufactured, and its effect is great as compared with the conventional etalon filter and its manufacturing method.

[Brief description of the drawings]

FIG. 1 is a diagram showing steps in an etalon filter and a method of manufacturing the etalon filter according to the present invention.

FIG. 2 is a view showing steps in an example of a conventional etalon filter and a method of manufacturing the same.

FIG. 3 is a view showing a finished state of a laminated substrate in a conventional etalon filter and a method of manufacturing the same.

[Explanation of symbols]

1: Synthetic quartz substrate, 2: Ultra thin etalon filter, 3:
Reflective film, 4 large substrate, 5 adhesive, 6 dielectric material,
7 ... acid resistant adhesive or wax, 8 ... etching tank,
9 ... etching etchant (etchant), 10,11 ...
Laminated substrate,

Claims (2)

[Claims] 1. An etalon filter comprising a quartz substrate, one main surface of which is machined and the other main surface of which is polished by etching. 2. A method for manufacturing an etalon filter having a dielectric thin film on both sides of a quartz substrate having a predetermined thickness,
Both surfaces of the quartz substrate are mechanically polished, the polished quartz substrate is bonded and fixed to a large substrate, wet etching is performed together with the large substrate to obtain the predetermined thickness, and the quartz substrate is separated from the large substrate. A method for manufacturing an ultrathin etalon filter, comprising depositing a dielectric film on both surfaces of the etalon filter.