JPH02186303A - Optical fiber with interference filter - Google Patents

Abstract

PURPOSE:To provide a device which combines an optical fiber and interference filter while eliminating the need for the intricate and precise adjustment necessary for the case of using the conventional interference filter by providing an interference film having a wavelength selecting filter function on at least one end face of the optical fiber consisting of a core and a clad enclosing the core. CONSTITUTION:The optical fiber 10 has the core 11 which is a light guide at its center and the core 11 is circumferentially enclosed by the clad 12. The end face of the optical fiber 10 is sufficiently smoothly polished to avoid the disturbance of the light propagated in the core 11 and the interference film 13 is formed on this end face. The light emitted from the core 11 or made incident to the core 11, therefore, transmits fully the interference film 13. The need for using other optical elements is eliminated for the optical system coupling at least the optical fiber 10 and the interference filter if this optical fiber 10 is used. The number of parts is decreased and the constitution of the device is simplified in the case of constituting the device using this interference filter and optical fiber. In addition, the adjustment of the device is facilitated and further, contribution is made to the miniaturization of the device.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an optical fiber with an interference filter.

More specifically, the present invention relates to a novel optical fiber configuration with an interference filter on its end face.

2. Description of the Related Art With the recent development of optical wave technology, various optical circuits using optical fibers as optical waveguides have been realized. Interference filters may be used to select wavelengths in such optical circuits.

An interference filter is a member formed by coating the surface of a glass plate with an interference film, and is used in conjunction with an optical fiber as described below.

FIG. 3(a) is a diagram showing the configuration of each element when the end of the optical fiber line and the light source are coupled through the interference filter as described above.

As shown in the figure, between the end face of the optical fiber 31 and the light source 34, a lens 32a, an interference filter 33, a lens 3
2b are arranged in this order on the optical axis of the optical fiber 31. That is, the light generated from the light source 34 is made into parallel light by the lens 32b, the wavelength is selected by the interference filter 33, and the light is converged by the lens 32a to enter the end face of the optical fiber 31.

Moreover, FIG. 3(b) is a diagram showing the configuration of each element when the ends of a pair of optical fiber lines are coupled together via an interference filter.

As shown in the figure, between the end face of the optical fiber 31a and the end face of the optical fiber 31b, a lens 32a1, an interference filter 33, and a lens 32b are connected to the optical fiber 31a in this order.
, 31b.

Here, for example, light emitted from the end face of the optical fiber 31a is made into parallel light beams by the lens 32b, wavelength-selected by the interference filter 33, and further converged by the lens 32H to enter the end face of the optical fiber 31b. .

Problems to be Solved by the Invention In the conventional method of using an interference filter as described above, it is necessary to adjust the position and posture of the optical system, including the optical fiber, the interference filter, and the lens, with extremely high precision. . That is, as mentioned above, the optical axis of the optical fiber and the lens,
If lenses, optical fibers, etc. are not arranged on the same optical axis, loss will increase and the quality of propagated light will deteriorate. However, making such adjustments using independent elements such as lenses and interference filters is a difficult task, and creating optical circuits using interference filters requires extremely sophisticated technology. .

Also, components such as lenses and interference filters are relatively large components compared to the dimensions (especially the thickness) of the optical fiber.
Furthermore, if members for fixing and covering these are included, the interference filter in actual use becomes a considerably large component.

Furthermore, since it is necessary to use several members including at least one pair of lenses in addition to the interference filter, the number of parts is large, making the various problems described above even more serious.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a novel optical element that solves the problems of the prior art described above and allows easier construction of an optical system including an interference filter.

Means for solving the problem, that is, according to the present invention, an optical fiber consisting of a core and a cladding surrounding the core is provided with an interference film having a wavelength selection filter function on at least one end face. An optical fiber with an interference filter is provided.

Function The optical fiber according to the present invention is characterized in that an interference filter is built directly into its end face.

That is, if the optical fiber according to the present invention is used, there is no need to use other optical elements at least for the optical system that couples the optical fiber and the interference filter. Furthermore, there is no need to perform optical adjustment between the interference filter and the optical fiber, making it extremely easy to manufacture and adjust an optical system including the interference filter.

In addition, as will be described in detail later, in the case of an application where an interference filter is inserted in the middle of an optical fiber line, the optical fiber of the present invention, which has an interference filter on the end face, and a normal optical fiber are simply butted together. The connection is completed in this step, and the overall structure of the device becomes extremely simple and compact.

As described above, the optical fiber with an interference filter according to the present invention not only simplifies the configuration of the device by reducing the number of parts when configuring a device using an interference filter and an optical fiber, but also simplifies the configuration of the device. This facilitates adjustment and further contributes to miniaturization of the device.

Incidentally, the optical fiber with an interference filter according to the present invention can be manufactured as follows. That is, the end face of a single-core or multi-core optical fiber is mirror-cut or mirror-polished, and the optical fiber is fixed in an interference film fabrication device so that the mirror-finished end face faces the evaporation source. An interference film can be formed. Here, various known vapor deposition apparatuses can be used as the interference film manufacturing apparatus.
The interference film can be formed by vapor deposition.

The present invention will be described in more detail below with reference to the drawings, but the following disclosure is only one example of the present invention and does not limit the technical scope of the present invention in any way.

Embodiment FIG. 1 is a diagram showing an example of the configuration of an optical fiber with an interference filter according to the present invention. In particular, the configuration near the end face of the optical fiber provided with the interference filter is shown by a cross section thereof.

The optical fiber IO has a core 11 serving as a leading waveguide at its center, and the core 11 is surrounded by a cladding 12. The end face of the optical fiber 10 is polished sufficiently smooth so as not to disturb the propagating light of the core 11, and an interference film 13 is formed on this end face.

Therefore, all of the light emitted from or incident on the core 11 passes through the interference film 13.

The optical fiber with an interference filter according to the present invention configured as described above can be used in the following manner.

That is, FIG. 2(a) is a diagram showing a configuration when the above-described optical fiber with an interference filter according to the present invention is coupled to a light source.

As shown in FIG. 2(a), in this device, the interference film 23
A white light source 24 is placed near the end face of an optical fiber 21 with a lens 22 interposed therebetween. In this device, white light generated by a light source 24 is converged onto the end face of an optical fiber 21 by a lens 22, passes through an interference film 23, and enters the optical fiber 21. Therefore, according to the specifications of the interference film used, the light propagating within the optical fiber 21 is limited to a specific wavelength or wavelength band.

Comparing the configurations of the device shown in FIG. 2(a) and the conventional device shown in FIG. 3(a), this device has 1
Since the lens 32b and the interference filter 33, which are independent members, which were necessary in the device shown in FIG. 3(a) are omitted, the number of parts is reduced. Further, the only adjustment required when manufacturing the device of this example is the optical adjustment between the lens 22 and the optical fiber 21.

Furthermore, FIGS. 2A and 2B are diagrams showing a configuration when an optical fiber with an interference filter according to the present invention is applied when an interference filter is inserted in the middle of an optical fiber line.

As shown in FIG. 2, this device is constructed by abutting an end face of an optical fiber 21a provided with an interference film 23 with an end face of a normal optical fiber 21b without an interference film. The two are joined by optical fibers 21a and 21. Both ends are inserted into a sleeve 25 having an inner diameter equal to the outer diameter of b, and the end of the sleeve 25 and the optical fiber 21a,
These are fixed by bonding the ends of 21b with an adhesive 26.

In the device configured in this way, for example, light propagated through the optical fiber 21b is transmitted through the interference film 23 and propagated to the optical fiber 21a.
The light propagating through 1a is limited to only light of a specific wavelength or wavelength band determined according to the specifications of the interference film 23.

Comparing the configurations of the device shown in FIG. 2(b) and the conventional device shown in FIG. 3(b), this device has the same functions as those shown in FIG. Since the lenses 32a and 32b and the interference filter 23, which is an independent member, are omitted, the number of parts is greatly reduced.

In addition, when manufacturing the device of this example, the sleeve 25
If it is manufactured accurately, the desired performance can be obtained with virtually no adjustment.

Effects of the Invention As detailed above, although the optical fiber with an interference filter according to the present invention has an extremely simple structure, it does not require complicated and precise adjustment that is required when using a conventional interference filter. can be omitted to form a device combining an optical fiber and an interference filter.

In addition, devices using this optical fiber with interference filters require fewer manufacturing steps due to a reduction in the number of parts (not only are they easier to downsize, but they are also simpler in structure, making them more durable). Improvements can also be expected in this respect.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a configuration example of an optical fiber with an interference filter according to the present invention, and FIG. FIG. 2(b) shows a configuration example in which the optical fiber μ with an interference filter according to the present invention is applied to a case where an interference filter is inserted in the middle of an optical fiber line. FIG. 3(a) is a diagram showing a typical configuration example when a light source and an optical fiber are coupled using a conventional interference filter; FIG. 3(a) is a diagram showing an example. It is a figure which shows the example of a structure when the conventional interference filter is inserted in the middle of an optical fiber line. [Main reference numbers] 10... Optical fiber, 11 12... Clad, 21.21a, 21b, 31.31a, 31b ・
22.22a, 22b, 32.32a, 32b -
23...Interference film, 33...24.34...Light source, 25...26...Adhesive...Core 5,...Optical fiber,...Lens, Interference filter, Sleeve,

Claims (1)

[Claims] An optical fiber with an interference filter, characterized in that an interference film having a wavelength selective filter function is provided on at least one end face of an optical fiber consisting of a core and a cladding surrounding the core.