JPH0242408A - Light multiplexer-demultiplexer - Google Patents

Abstract

PURPOSE:To decrease the number of parts, to use the title device even at a narrow wavelength interval and to stabilize the connection with a fiber by using a diffraction grating composed of unequal interval curves for a wave- length demultiplexing element. CONSTITUTION:The title device is equipped with a wavelength demultiplexing element 2 to multiplex light signals from light sources whose wavelengths are different or branch a light signal composed of many wavelengths into the light signals of the wavelengths. The diffraction grating composed of the unequal curves is used for the wavelength demultiplexing element. That is to say, the title device has a function to demultiplex the light signal emitted spreadingly from a fiber 3 by a curve grating like the external circumstance part of a Fresnel lens and converge them to optical fibers 4 corresponding to the wavelengths. Conversely, when the light signals whose wavelengths are different are emitted from the fibers, all the light signals can be connected to one optical fiber. Thus, it can be used at the narrow wavelength interval with a simple structure and the connection with the fiber is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to an optical multiplexer/demultiplexer used in wavelength division multiplexing optical communications.

(b) Conventional technology Conventionally, in wavelength division multiplexing optical communications, optical multiplexers and demultiplexers are used to multiplex and transmit optical signals of multiple wavelengths, and then the receiving side splits the optical signals into optical signals of each wavelength again. ing. For example, in the general wavelength division multiplexing optical communication shown in Fig. 5, each channel 6 on the transmitting side
1, each light emitting source 62 emits a plurality of optical signals having different wavelengths. The optical multiplexer/demultiplexer 63 combines optical signals from light sources with different wavelengths into one optical signal, and propagates it through one optical fiber 64 . The optical multiplexer/demultiplexer 65 on the light receiving side branches one optical signal consisting of multiple wavelengths into optical signals of each wavelength.
The light is emitted to a light receiving element (or optical fiber) 66 corresponding to each wavelength.

In such an optical multiplexer/demultiplexer, wavelength demultiplexing elements for demultiplexing and condensing optical signals are conventionally shown in FIGS.
The methods shown in FIG. 6(B) and FIG. 6(C) are used.

The optical multiplexer/demultiplexer shown in FIG. 6(A) uses an interference filter 71 as a wavelength demultiplexer. In other words, in this optical multiplexer/demultiplexer, one input fiber 73 and a large number of output fibers 74 are provided on the upper and lower surfaces of the glass plate 72, and a dielectric multilayer filter (interference filter) 71 is arranged. Input fiber 73
One optical signal consisting of multiple wavelengths is inputted by , propagates through a microlens 75 and a glass substrate 72 , is split into optical signals of each wavelength by an interference filter 71 , and is output from an output fiber buffer 4 corresponding to each wavelength. Emits light.

The optical multiplexer/demultiplexer shown in FIG. 6(B) uses a linear grating using an optical waveguide 81 as a wavelength demultiplexing element. That is, a thin plate-shaped diffraction grating (silicon) 83 and a cylindrical concave block 84 are combined on one end side of a two-dimensional waveguide block 82 that has a waveguide layer 81 inside, and the other end side of the two-dimensional waveguide block 82 is A fiber array 85 is arranged in correspondence with the waveguide layer 81. The waveguide layer 81 and the diffraction grating 83 separate and condense optical signals.

In the optical multiplexer/demultiplexer shown in FIG. 6(C), a linear grating using lenses is used as a wavelength demultiplexing element. It has one input fiber 92 and an output fiber array 93, with a diffraction grating (silicon) 94 arranged on the other side. 1 input fiber 9
One optical signal consisting of multiple wavelengths input by 2 is
The optical signal is branched into optical signals of each wavelength via the assembled lens 91 and the diffraction grating 94, and outputted by the output fiber array 93 corresponding to each wavelength.

(c) Problems to be Solved by the Invention In the method of using the interference filter shown in FIG. 6(A) as a wavelength demultiplexing element, the number of parts is large and the structure is complicated. The width of the equivalent area is wide. For this reason, there is a disadvantage that it cannot be used when the wavelength interval of optical signals is as narrow as several nanometers. Furthermore, the method using the optical waveguide shown in FIG. 6(B) has a disadvantage in that the coupling t0 loss between the diffracted light from the optical fiber, the optical waveguide, and the grating and the optical waveguide light is large. Furthermore, the system using a lens and linear grating shown in FIG. 6(C) has a large number of parts including the lens, and therefore optical axis deviations are likely to occur due to vibrations or temperature changes. Therefore, there were disadvantages such as poor environmental resistance.

The object of the present invention is to solve the above-mentioned problems and provide an optical multiplexer/demultiplexer that has a small number of parts, can be used even at narrow wavelength intervals, and has stable coupling with fibers.

(d) Means and operation for solving the problem In order to achieve this object, the optical multiplexer/demultiplexer of the present invention has the following configuration.

An optical multiplexer/demultiplexer is an optical multiplexer/demultiplexer equipped with a wavelength demultiplexer element that multiplexes multiple optical signals from light sources with different wavelengths or branches an optical signal consisting of multiple wavelengths into optical signals of each wavelength. The wavelength demultiplexing element is characterized in that it uses a diffraction grating consisting of a group of curves at unequal intervals.

An optical multiplexer/demultiplexer having such a configuration uses a special wavelength demultiplexing element. As the wavelength demultiplexing element, for example, a chirped grating or a Fresnel lens is used. In other words, it is set to a curved grating that resembles the outer circumference of a Fresnel lens, and has the effect of focusing light at the same time as splitting light.

For example, this special wavelength demultiplexing element is fixedly placed in the center of an optical multiplexer/demultiplexer body, one input optical fiber is placed at one end of the body, and a group of receiving optical fibers are placed at the other end. . One input fiber outputs a plurality of optical signals having different wavelengths that propagate inside the fiber.

A wavelength demultiplexing element has the function of demultiplexing an optical signal emitted from a fiber while spreading, using a curved grating similar to the outer periphery of a Fresnel lens, and focusing the light onto an optical fiber corresponding to each wavelength.

This configuration is reversible. In other words, when optical signals with different wavelengths are emitted from each fiber, each optical signal has a
Can be coupled to optical fibers in trees.

Therefore, it has an extremely simple configuration, can be used even with narrow wavelength intervals, and exhibits effects such as stable coupling with fibers.

(E) Embodiment FIG. 2 is a sectional view of a main part showing a specific embodiment of the optical multiplexer/demultiplexer according to the present invention.

In the optical multiplexer/demultiplexer, a wavelength demultiplexing element 2 is fixedly disposed in the center of a case body 1 via a fixing member 11, one input optical fiber 3 is provided at one end of the case body 1, and a light receiving optical fiber is provided at the other end. A group of optical fibers 4 are arranged in a conductive manner.

The wavelength demultiplexing element 2, which is a feature of this invention, is shown in FIG. 1(A).
As shown in the front view of FIG. 1 and the cross-sectional view of FIG. As the wavelength demultiplexing element 2, for example, a chirped grating or a Fresnel lens is used. In other words, by setting a curved grating on the outer circumference of the Fresnel lens,
It has a light focusing effect at the same time as demultiplexing. Furthermore, by blazing the cross section, the lens body is made highly efficient.

In an optical multiplexer/demultiplexer having such a configuration, one input fiber 3 outputs a plurality of optical signals (λ1, λ2, λ3, λ4) having different wavelengths propagating inside. The wavelength demultiplexing element 2 has the function of demultiplexing the optical signal emitted from the fiber 3 while spreading, using a curved grating similar to the outer periphery of a Fresnel lens, and focusing the light onto the optical fiber 4 corresponding to each wavelength. have This configuration is reversible. That is, when optical signals with different wavelengths are emitted from each fiber, any of the optical signals can be coupled to one optical fiber 3.

Therefore, the optical multiplexer/demultiplexer can be formed compactly with an extremely simple configuration, and can be used even when the wavelength spacing of optical signals is narrow, and the coupling with fibers is stabilized.

FIG. 3 is an explanatory diagram showing another embodiment of the wavelength demultiplexing element 2. In this embodiment, an example is shown in which the wavelength demultiplexing element 2 is made into a reflection type wavelength demultiplexing element 2 by applying a metal stem to the wavelength demultiplexing element 2 and making the wavelength demultiplexing element 2 a mirror.

In this embodiment, a plurality of optical signals (λ1, λ2, λ3) having different wavelengths are emitted from one input optical fiber 3, and are separated and reflected by the wavelength demultiplexing element 2, and corresponding to each wavelength. The light is emitted to the light-receiving element 4.

FIG. 4 is a sectional view of main parts showing another embodiment of the optical multiplexer/demultiplexer. In this embodiment, a wavelength demultiplexing element (transmission type) 2 is provided in the center of the case body 1, and one input optical fiber 3 is electrically connected to one end of the case body 1, and the other end A photodetector (light receiving element) 4 is provided on the side.

In this embodiment, a wavelength demultiplexing element 2 demultiplexes an optical signal from an optical fiber 3 that transmits an optical signal consisting of a plurality of wavelengths, and a photodetector corresponding to each wavelength (a light receiving element corresponding to each wavelength ) 4 to separate and focus the light.

Each light receiving element 4 receives the emitted wavelength and outputs an electric signal.

(f) Effects of the Invention In this invention, as described above, since an optical multiplexer/demultiplexer is constructed using a wavelength demultiplexing element using a diffraction grating consisting of a group of unequally spaced curves, the number of parts is reduced. It is possible to construct a compact optical multiplexer/demultiplexer with a small amount of noise. In addition, the optical multiplexer/demultiplexer using this wavelength demultiplexing element can be used even when the wavelength spacing of optical signals is narrow, and the coupling with the fiber is stable and has excellent environmental resistance. It achieves its purpose and has excellent effects.

[Brief explanation of the drawing]

FIG. 1(A) is a front view showing the wavelength demultiplexing element of the example;
FIG. 1(B) is a cross-sectional view showing the wavelength demultiplexing element of the example,
FIG. 2 is a sectional view of a main part showing an example optical multiplexer/demultiplexer, FIG. 3 is an explanatory diagram showing another example of the wavelength demultiplexer, and FIG. 4 is another embodiment of the optical multiplexer/demultiplexer. FIG. 5 is a sectional view of a main part showing an example; and FIG.
) is an explanatory diagram of the main parts of a conventional optical multiplexer/demultiplexer, and Figure 6 (B
) is an explanatory diagram of the main parts of a conventional optical multiplexer/demultiplexer, and Figure 6 (C
) is an explanatory diagram of the main parts of a conventional optical multiplexer/demultiplexer. 2: wavelength demultiplexing element, 3: input optical fiber, 4: receiving side optical fiber. Patent applicant Tateishi Electric Co., Ltd. Agent
Patent Attorney Shigenobu Nakamura (A) (B) 2: Moat 10,000 - Shin Motoko KafujJ Figure ＼ 2: Hama Chikari 3, Human Power Fiber 4, Acceptance 111 Yu Fufuiha Diagram ? ＼ 1゛One-pronged A book 2, Leather (Zuna-use thread 3: Fiber for human power 4: Reception, A11) Optical fiber

Claims (1)

[Claims] (1) Combine multiple optical signals from light sources with different wavelengths,
Or an optical multiplexer/demultiplexer comprising a wavelength demultiplexing element that branches an optical signal consisting of multiple wavelengths into optical signals of each wavelength, where the wavelength demultiplexing element uses a diffraction grating consisting of a group of curves at unequal intervals. An optical multiplexer/demultiplexer characterized by: