JPH02311803A - Optical filter - Google Patents

Abstract

PURPOSE:To manufacture the optical filter as designed at high yield by retreating the polished end surface of an optical fiber from the polished end surface of a ferrule. CONSTITUTION:The polished end surface of the optical fiber 1 is arranged behind the polished end surface of the ferrule 2-1(2-2) and both the ferrules are made to meet each other by using a sleeve 3 and then an air layer 5 is formed, so that dielectric multilayered films 4-1 and 4-2 formed on end surfaces of optical waveguides 1 do not contact each other. Therefore, even when the ferrules 2-1 and 2-2 are attached and detached repeatedly, a filter film 4-1 (4-2) formed on the polished end surface of an optical fiber 1 never break, and the dielectric multilayered film formed on the end surface of one optical fiber with the wavelength characteristics of the filter is made to operate as a reflection preventive film, thereby easily judging the characteristics of the filter. Consequently, the optical fiber is formed as designed at high yield.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an optical filter that is inserted into an optical transmission line and blocks unnecessary wavelengths used in optical communication system transmission lines and optical measurement. .

(Prior Art) A conventional optical fiber filter (hereinafter referred to as an optical filter) will be described with reference to FIGS. 2 and 3.

FIG. 2 is a side view of the configuration of a conventional bulk type optical filter, in which 1 is an optical fiber, 4 is a dielectric multilayer film, 6 is a lens for collimating light, and 7 is a glass block. A dielectric multilayer film 4 is formed on the end face. However, in such a bulk configuration, the number of parts that make up the filter is large, and optical axis adjustment is also extremely difficult.
It was difficult to make the filter smaller.

Another conventional optical filter devised to solve this problem is shown in FIG. FIG. 3(a) is a side view showing the configuration, and FIG. 3(b) is an enlarged view of the negative part of FIG. 3(a), in which 2-1 and 2-2 are ferrules, 3 is a sleeve,
4-1 and 4-2 indicate dielectric multilayer films. To manufacture this optical filter, first polish the ferrules 2-1 and 2-2 containing the optical fibers l, and then polish the polished end faces (
Dielectric multilayer films 4-1 and 4-2 are formed on the ferrule (the polished surface of the ferrule and the polished surface of the optical fiber are on the same plane).

Then, attach the two ferrules 2-1 and 2-2 to the sleeve 3.
The core parts of the two optical fibers are aligned and fixed by passing them through the fibers. With this configuration, the optical axis of the optical fiber 1 can be automatically adjusted by using the precise IJ + ferrule 3 and ferrule 2-1, 2-2, and the number of parts is small, making the filter compact. can be converted into However, in this configuration, the wavelength-dependent characteristics of the optical filter differ from the dielectric multilayer film 4.
Since it is determined by the composite characteristics of -1 and 4-2, the filter characteristics of this optical filter cannot be easily estimated from the wavelength characteristics of one ferrule with a dielectric multilayer film formed at the end of the optical fiber. Match the two ferrules,
When both dielectric multilayer films are brought into close contact with each other, an air layer may be formed between the two dielectric multilayer films, making it extremely difficult to form a filter with the characteristics as designed. Furthermore, since the dielectric multilayer films formed on the end faces of the optical fibers 1 are brought into close contact with each other, it is virtually impossible to attach and detach them due to the abrasion characteristics of the dielectric multilayer films, resulting in a poor yield of optical filters.

(Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide an optical filter that can be manufactured as designed and with a high yield.

(Means for solving problems) The basic configuration of the optical filter of the present invention is shown in FIG.

In FIG. 1, l is an optical fiber, 2-1 and 2-2
3 is a ferrule, 3 is a sleeve, 4-1 and 4-2 are dielectric multilayer films, and 5 is an air layer. The biggest feature compared to conventional optical filter configurations is the ferrule 2-1 or 2-
The polished end face of the optical fiber is retracted (retracted) from the polished end face of the optical waveguide 1, and when both ferrules are matched using the sleeve 3, an air layer 5 is generated, and the dielectric multilayer formed on the end face of the optical waveguide 1 is The membranes should not come into contact with each other.

In the structure of the optical filter of the present invention, an air layer 5 is always created between the filter films 4-1 and 4-2, so even if the two ferrules 2-1 and 2-2 are repeatedly attached and detached, the light Filter film 4-1 or 4-2 formed on the polished end face of fiber 1
By using the dielectric multilayer film formed on one optical fiber end face as an antireflection film, the wavelength characteristics of the filter can be changed from the characteristics of the dielectric multilayer film on the other optical fiber end face. , there is an advantage that the characteristics of the optical filter of the present invention can be easily inferred.

Therefore, compared to the configuration of the optical filter shown in Fig. 3, the characteristics of the filter can be evaluated at the time when each filter film is formed on the end face of the ferrule, and the two ferrules can be attached and detached, so that the optical Filters can be manufactured with good yield.

(Examples) The present invention will be described in more detail below with reference to the drawings, but the examples disclosed below are merely illustrative of the present invention and are not intended to limit the scope of the present invention. do not have.

FIG. 1 is a side view showing the configuration of an embodiment of the present invention.

The optical fiber 1 is a single mode optical fiber with an outer diameter of 125 μm, and the ferrules 2-1. Zirconia was used as the material for 2-2, and phosphor bronze was used as the material for the sleeve 3. This optical filter was manufactured by incorporating the optical fiber 1 into the ferrule 2-1 or 2-2, and polishing its end face.

Further, the structure in which the polished end face of the optical fiber is set back from the ferrule was achieved by puff polishing during polishing, and the end face was set back by about 3 μm. Thereafter, a dielectric multilayer film 4-1 or 4-2 was formed on the polished end surface by vapor deposition. Dielectric multilayer film 4-
1 reflects approximately 100% of light with a wavelength of 0.8 to 0.9 μm and transmits approximately 100% of light with a wavelength of 1.45 to 1.6 μm, and the dielectric multilayer film 4-2 reflects approximately 100% of light with a wavelength of 1.45 to 1.6 μm. It was made to transmit approximately 100% of the wavelength of .6 μm. In addition, it was determined whether the desired wavelength characteristics were obtained in this process. Furthermore, the ferrules 2-1 and 2-2 containing the optical fiber 1 coated with the dielectric multilayer film 4-1 or 4-2 are inserted into the sleeve 3, and the end faces of both ferrules are aligned, thereby allowing the optical Optical axis alignment between fibers can also be achieved.

The characteristics of the optical filter manufactured in this way are as follows: wavelength 0.
Reflects approximately 100% of light from 8 to 0.9 μm, wavelength 1.45
A property of transmitting about 100% of the wavelength of ~1.6 μm was stably obtained, and there was no change in the property even with desorption.

Note that, in the optical filter of the present invention, a dielectric multilayer film may be used instead of the above-mentioned dielectric multilayer film.

(Effects of the Invention) As explained above, the optical filter of the present invention is configured such that the polished end face of the optical fiber is set back (retracted) from the polished end face of the ferrule, and therefore a sleeve is not used. When both ferrules are brought into alignment, an air layer is created, and the dielectric multilayer film formed on the end face of the optical fiber does not come into close contact. As a result, the dielectric multilayer films on the end faces of the optical fibers do not wear out each other and can be attached and detached. Further, compared to the configuration of a conventional optical filter, since one dielectric multilayer film acts as an antireflection film, the filter characteristics of the present invention can be easily inferred from the characteristics of the other dielectric multilayer film.

From the above, there is an advantage that optical filters as designed can be manufactured with good yield and manufacturing costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a side view showing the configuration of an embodiment of the optical filter of the present invention, FIG. 2 is a configuration diagram of an example of a conventional optical filter, and FIG.
) is a side view showing the configuration of another example of a conventional optical filter, and FIG. 3(b) is a partially enlarged view of FIG. 3(a). ■...Optical fiber 2-1.2-2...Ferrule 3...Sleeve 4, 4-1.4-2...Dielectric multilayer film 5...Air layer 6...Lens 7 ...Glass block. Figure 1 - Death fiber Figure 2 (a) Figure 3

Claims (1)

[Claims] 1. A pair of optics consisting of an optical fiber and a ferrule in which a dielectric film is formed on the polished end face of the optical fiber and the polished end face of the ferrule that holds the optical fiber. In an optical fiber type filter in which the dielectric films of the components are butted and in contact with each other and are aligned so that the center lines of the pair of optical components substantially coincide, a filter film made of the dielectric film. An optical filter characterized in that an end face of an optical fiber comprising: is arranged to be set back from an end face of the ferrule. 2. The optical filter according to claim 1, wherein one of the dielectric films of the pair of optical components acts as an antireflection film for a predetermined wavelength.