JPH11264916A - Optical demultiplexer/multiplexer and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical demultiplexer/multiplexer which has simple constitution, low insertion loss, and reduced variance in characteristics between channels while maintaining high precision, and a manufacturing method for it. SOLUTION: The optical demultiplexer multiplexer is constituted by fixing on a base 1 an optical demultiplexing and multiplexing element 2 formed of a transparent parallel flat plate having on at least one surface multi-layered interference filter films 61 and 62 which transmit lights of specific wavelengths of an incident light consisting of plural wavelengths and reflects lights of other wavelengths, optical fibers 31 and 32 for input which make the light incident on the optical demultiplexing multiplexing element 2, and optical fibers 33 and 34 for output which transmit the projection light of the optical demultiplexing multiplexing element 2. The optical demultiplexer multiplexer is obtained by adjusting the optical demultiplexing multiplexing element 2, inserted into a rectangular groove 4 formed on the base 1, along the rectangular groove 4 so that the intensity of the transmitted light of the light made incident through the optical fiber 31 for input becomes maximum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for wavelength division multiplexing optical communication, which is optical multiplexing communication. One terminal branches one wavelength light from a plurality of wavelengths, or multiplexes light from one terminal to a trunk line. To an optical demultiplexer / optical multiplexer for performing the operation.

[0002]

2. Description of the Related Art In optical multiplex communication, an optical multiplexer for confining and transmitting light of a plurality of wavelengths in a single optical fiber and a light of a plurality of wavelengths confined in a single optical fiber are respectively used. An optical demultiplexer for demultiplexing to an optical fiber and guiding it to an optical fiber is indispensable.

FIG. 4 is a diagram showing a conventional optical demultiplexer. Multilayer interference filter films 81, 82, 83,
Light of each wavelength is emitted from each output port through 84, 85, 86 and the prism 10. A plurality of wavelengths (λ ₁ to
Of the incident light of λ ₆ ), first, light having a wavelength of λ ₁ passes through the multilayer interference filter film 81, but light having wavelengths of λ _{2 to} λ ₆ is reflected. Next, the multilayer interference filter film 82
In, light having a wavelength of λ ₂ passes, but light having a wavelength of λ _{3 to} λ ₆ is reflected. Hereinafter, similarly, the light demultiplexed into a single wavelength for each port is emitted.

Conversely, when light of each wavelength (λ _{6 to} λ ₁ ) is input from each port to this optical demultiplexer, the light of each wavelength is multiplexed and the light emitted from the rod lens 7 is multiplexed. Functions as a wave filter.

[0005]

However, these optical demultiplexers / combiners have complicated components. High precision positioning and adjustment are required for assembling each component. Further, there is a problem that the insertion loss between the ports is likely to vary. The multiple reflection type optical demultiplexer having the configuration shown in FIG. 4 has six rod lenses 9 and multilayer interference filter films 81 to 81.
86, a rod lens 7, each prism 10, etc., it is reported that the insertion loss varies from 2.5 dB to 3.7 dB as a characteristic example of 6 channels.

The present invention provides an optical demultiplexer / optical multiplexer having a simpler configuration, low insertion loss, and reduced variation in characteristics between channels while maintaining high accuracy, and a method of manufacturing the same. The purpose is to do.

[0007]

SUMMARY OF THE INVENTION The present invention provides a multi-layer interference filter film that transmits light of a specific wavelength and reflects light of other wavelengths among at least one surface of incident light having a plurality of wavelengths. An optical demultiplexing / combining element formed of a transparent parallel plate, an input optical fiber for inputting light to the optical demultiplexing / combining element, and an output for transmitting light emitted from the optical demultiplexing / combining element. An optical fiber for use is an optical demultiplexer / combiner fixed on a base.

Further, in the optical demultiplexer / combiner of the present invention, the light incident direction is set at an angle in the range of 20 ° or more and 45 ° or less with respect to the perpendicular to the multilayer interference filter film, and is bonded to each other. And a plurality of transparent parallel flat plates.

In the optical demultiplexer / multiplexer according to the present invention, the input optical fiber and the output optical fiber are fixed to a V-shaped groove formed on a base. The multiplexing element is fixed to a rectangular groove formed on the base.

According to the present invention, in the optical demultiplexing / combining element, the incident light from the input optical fiber with respect to the surface of the optical demultiplexing / combining element is not less than 80 ° and not more than 100 °. This is an optical demultiplexer / combiner configured to be incident at an angle.

Further, the present invention comprises a transparent parallel flat plate formed with a multilayer interference filter film that transmits light of a specific wavelength among incident lights of a plurality of wavelengths and reflects light of other wavelengths. The position of the optical demultiplexing / multiplexing element is adjusted so that the transmitted light intensity of the incident light from the input optical fiber is maximized in the optical demultiplexing / multiplexing element inserted in the square groove formed on the base. This is a method for manufacturing the above-described optical demultiplexer / multiplexer, which slides along a rectangular groove to adjust and fix.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram of a configuration of an optical demultiplexer / combiner according to an embodiment of the present invention. FIG. 1A is a plan view of an optical demultiplexer / combiner, and FIG. 1B is a diagram showing a configuration and a manufacturing method of the optical demultiplexer / combiner. FIG. 2 is a diagram showing a state in the middle of the process of manufacturing the optical demultiplexing / combining element used in the optical demultiplexing / combining device according to the embodiment of the present invention.

First, as shown in FIG. 2, a multilayer interference filter film 8 was formed on the surface of three transparent substrates 5 each having a parallel plane and having a thickness of about 100 μm and made of white glass.
Multilayer interference filter film 8 formed on the surface of transparent substrate 5
A ZnS film as a high-refractive-index film and a spacer film, and a MgF ₂ film as a low-refractive-index film, respectively.
Then, these transparent substrates 5 were overlapped and adhered to each other. Then, as shown by a broken line in FIG. 2, the substrate was optically cut at an angle of 45 ° with respect to a perpendicular to the surface of the transparent substrate, and optically polished to produce an optical demultiplexing / combining element.

FIG. 3 shows an optical demultiplexing device manufactured in this manner.
FIG. 4 is a diagram illustrating spectral characteristics of a multiplexing element. From FIG. 3, the optical demultiplexing / multiplexing element transmits only light having a wavelength of 1550 nm,
It can be seen that light of other wavelengths is reflected.

Note that, with respect to the perpendicular to the surface of the transparent substrate 5, 4
The optical demultiplexing / combining element manufactured by cutting at an angle smaller than 5 ° exhibited smaller polarization dependence, and the angle range was appropriately from 45 ° to 20 °.

Next, the configuration of an optical demultiplexer / combiner using the optical demultiplexer / combiner and a method of manufacturing the same will be described with reference to FIG.

Two parallel V-shaped grooves 3 are formed on the base 1 of the silicon plate for fixing the optical fibers, and the input optical fibers 31 and 32 and the output optical fibers 33 are formed in the V-shaped grooves 3. , 34 are adhered and fixed. In the present embodiment, a single mode fiber is used. Further, a rectangular groove 4 having a width of about 150 μm for fixing the optical demultiplexing / combining element 2 was provided. Actually, two V-shaped grooves 3
Since the long input optical fibers 31 and 32 were fixed, and the other one divided by forming the rectangular groove 4 was used as the output optical fibers 33 and 34, the production was further facilitated.

The square groove 4 is provided with the input optical fibers 31 and 3.
2. The output optical fibers 33 and 34 are formed almost vertically. Preferably, light emitted from the input optical fibers 31 and 32 is reflected on the surface of the optical demultiplexing / combining element 2 inserted into the rectangular groove 4, and is again returned to the original input optical fibers 31 and 32.
In order to avoid incident on the optical fiber, the rectangular groove 4 may be formed at an angle of 80 ° or more and 100 ° or less with respect to the input optical fibers 31 and 32 and the output optical fibers 33 and 34. In order to prevent reflected light from returning, 9
It is desirable to avoid 0 °.

Thereafter, the optical demultiplexing / combining element 2 prepared above was inserted into the square groove 4. At this time, for example, a laser beam is input from the input optical fiber 31, the light intensity is monitored by the output optical fiber 33 through the optical demultiplexing / multiplexing element 2, and the light demultiplexing / multiplexing element is monitored. The position of No. 2 was adjusted by sliding along the rectangular groove 4 and fixed by bonding, thereby completing the manufacture of the optical demultiplexer / combiner.

The input optical fiber 3 of the optical demultiplexer / combiner
When you enter the light of n wavelengths lambda ₁ to [lambda] _i to [lambda] _n to 1,
Light having a wavelength λ _i determined by the characteristics of the multilayer interference filter film passes through the multilayer interference filter film 61 and is input to the output optical fiber 33, and light having other wavelengths is reflected by the multilayer interference filter film 61. The light is split by the multilayer interference filter film 62 and is incident on the output optical fiber 34. On the other hand, the light of the wavelength λ _i input from the optical fiber 32 passes through the multilayer interference filter film 62 and is input to the optical fiber 34 and multiplexed.

The optical demultiplexer / combiner according to this embodiment has a wavelength 1
When a plurality of lights in the 550 nm band were incident, the average value of the insertion loss was 1.27 dB, and the variation was 0.32 dB.

In this embodiment, a single mode fiber is used as the input optical fiber and the output optical fiber. However, the present invention can be similarly applied to a multimode fiber, a TEC fiber, and a polarization maintaining fiber. is there. In particular, in a TEC fiber formed such that the refractive index distribution gradually changes near the entrance / exit surface and emits / enters light thicker than a normal single mode optical fiber, good characteristics are expected in terms of transmission loss.

In the embodiment of the present invention, a white plate glass is used for the substrate, but an optical glass such as BK7 or a single crystal such as quartz may be used.

Further, the base is not limited to the silicon plate, but may be a single crystal such as the above-mentioned white plate glass, optical glass, and quartz, or a material having a small internal strain such as ceramic or steel.

In this embodiment, ZnS is used for the high refractive index film of the multilayer interference filter film.
_{2, Ta 2 O 3, ZrO} 2 even better, likewise, may be SiO _2, Al ₂ O ₃ instead of the MgF ₂ low-refractive index film.

In the optical demultiplexer / multiplexer, the characteristic factors mainly depend on the film quality of the multilayer interference filter film and the positioning accuracy of the optical demultiplexer / multiplexer. In the case of the conventional optical demultiplexer / multiplexer shown in FIG. 4, two-dimensional positioning adjustment is required, whereas the optical demultiplexer / multiplexer according to the present embodiment employs a square groove. Accordingly, only one-dimensional positioning adjustment is required, and products having substantially uniform characteristics can be efficiently manufactured.

In the present embodiment, a multilayer interference filter film having a stable quality can be obtained by correcting the film thickness of the multilayer interference filter film formed at the stage of fabricating the optical demultiplexing / combining element by cutting diagonally. Was done.

[0029]

As described above, according to the present invention, an optical demultiplexer having a simpler configuration, a low insertion loss, and a reduced variation in characteristics between channels while maintaining high accuracy. -An optical multiplexer can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration of an optical demultiplexer / combiner according to an embodiment of the present invention. FIG. 1A is a plan view of an optical demultiplexer / combiner.
FIG. 1B is a diagram showing a configuration and a manufacturing method of the optical demultiplexer / combiner.

FIG. 2 is a diagram showing a state in the middle of the process of manufacturing an optical demultiplexing / multiplexing element used for the optical demultiplexing / combining device according to the embodiment of the present invention.

FIG. 3 is a diagram showing spectral characteristics of an optical demultiplexing / combining element used in an optical demultiplexing / combining device according to an embodiment of the present invention.

FIG. 4 is a diagram showing a conventional optical demultiplexer.

[Explanation of symbols]

Reference Signs List 1 base 2 optical demultiplexing / combining element 3 V-shaped groove 4 rectangular groove 5 transparent substrate 7 rod lens 8 multilayer interference filter film 9 rod lens 10 prism 31, 32 input optical fiber 33, 34 output optical fiber 61, 62 multilayer interference filter film 81, 82, 83, 84, 85, 86 multilayer interference filter film λ _{1 to} λ ₆ wavelength

Claims (6)

[Claims] 1. A transparent parallel flat plate having a multilayer interference filter film formed on at least one surface that transmits light of a specific wavelength and reflects light of other wavelengths out of incident light having a plurality of wavelengths. An optical demultiplexing / combining device, an input optical fiber for inputting light to the optical demultiplexing / combining device, and an output optical fiber for transmitting light emitted from the optical demultiplexing / combining device are basically provided. An optical demultiplexer / combiner fixed on a table. 2. The optical demultiplexing / combining element, wherein an incident direction of light is set to an angle of 20 ° or more and 45 ° or less with respect to a perpendicular line of the multilayer interference filter film, and is bonded to each other. 2. The optical demultiplexer / combiner according to claim 1, comprising a plurality of transparent parallel flat plates. 3. The optical demultiplexer according to claim 1, wherein the input optical fiber and the output optical fiber are fixed to a V-shaped groove formed on the base. Combiner. 4. The optical demultiplexing / combining device according to claim 1, wherein the optical demultiplexing / combining element is fixed to a rectangular groove formed on the base. Waver. 5. The optical demultiplexing / combining element, wherein the incident light from the input optical fiber is at an angle of 80 ° or more and 100 ° or less with respect to the surface of the optical demultiplexing / combining element. The optical demultiplexer / combiner according to any one of claims 1 to 4, wherein the optical demultiplexer is configured to be incident. 6. An optical demultiplexer comprising a transparent parallel plate having a multi-layer interference filter film for transmitting light of a specific wavelength out of incident light of a plurality of wavelengths and reflecting light of other wavelengths. Insert the multiplexing element into the square groove formed on the base,
The position of the optical demultiplexing / combining element is adjusted by sliding along the rectangular groove and fixed so that the transmitted light intensity of the incident light from the input optical fiber is maximized. Item 6. The method for manufacturing an optical demultiplexer / combiner according to any one of Items 1 to 5.