JPS5937520A - Wavelength multiplex demultiplexer - Google Patents

Abstract

PURPOSE:To allow one wavelength multiplex demultiplexer to perform demultiplexing covering plural wavelengths, and to reduce its size and cost, by sticking an amorphous semiconductor film to one end surface of a convergent rod lens which varies in refractive index radially from the center part almost with a square distribution. CONSTITUTION:The amorphous semiconductor 7 vapor-deposited on one end surface 6 of the convergent rod lens 5 varies in refractive index when irradiated with light having wavelength close to absorption edge, forming a diffraction grating 8 of interference fringes. An incident wave 10 having wavelengths lambda1, lambda2, and lambda3 enters the rod lens 5 from an end surface 9 through a fiber 11 and is reflected by the diffraction grating 8. Its angle of reflection is different depending upon the wavelengths, and the light is focused on different positions on the end surface 9, thereby demultiplexing light signals with the wavelengths lambda1, lambda2, and lambda3 from fibers 21, 31, and 41 couled with the positions.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wavelength multiplexer/demultiplexer used in an optical communication system. Note that the wavelength multiplexer/demultiplexer referred to herein also includes a wavelength multiplexer/demultiplexer.

In recent years, with the development of optical communication technology, increasing the transmission capacity has become increasingly important, and wavelength multiplexing transmission, which transmits optical signals of multiple wavelengths through one transmission medium (optical fiber), has begun to be implemented. became. To do this, a wavelength multiplexer/demultiplexer (
A multiplexer) is essential.

As shown in Figure 1, conventional wavelength multiplexing/demultiplexing filters reflect light of a specific wavelength and transmit light of other wavelengths.
This is a configuration in which multiplex units are connected in cascade to sequentially demultiplex and extract light of desired wavelengths. That is, the wavelength λ7. λ,,λ1
．． Incoming wave 10 wavelength-multiplexed by optical signal of λ4
is input to the demultiplexing/multiplexing unit 1 via fiber 9. The demultiplexing/multiplexing unit 1 is a rod lens 61.6
2 and a dielectric multilayer film IIM1, the dielectric multilayer film HM has a wavelength λ3. λ, reflects the light of wavelength λ
5. Transmits light of λ. The reflected wavelength λ,, λ,
The light is further incident on the demultiplexing/multiplexing unit 2, and the transmitted wavelength λ8. After the optical path of the light λ is changed by the optical path changing unit 4, it is made to enter the demultiplexing/multiplexing unit 3. The demultiplexing/multiplexing unit 2 is composed of rod lenses 51 and 52 and dielectric multilayer JIIHM2, and transmits light with a wavelength λ1 and makes it enter the fiber f, and reflects light with a wavelength λ2 and makes it enter the fiber f. . Demultiplexing/multiplexing unit 3
Similarly, the rod lenses 81 and 82 and the current visiting body multilayer film HM,
It transmits light with wavelength λ and outputs it via fiber f, and reflects light with wavelength λ4 and outputs it from fiber f4.

The conventional duplexer described above has a demultiplexing/multiplexing unit of 1°2.3
etc. are connected in multiple stages to sequentially extract the desired wavelength light, so if the number of multiplexed light waves is large, a correspondingly large number of demultiplexing/multiplexing units are required, making the structure complicated. The disadvantage is that it cannot be made smaller or more economical. Furthermore, when assembling the multiplexer and demultiplexer, it is necessary to strictly control the positional accuracy of each unit, and the assembly requires a great deal of time and effort, making it unsuitable for mass production.

An object of the present invention is to solve the above-mentioned conventional drawbacks and to provide a small and inexpensive wavelength multiplexer/demultiplexer that enables multiple wavelengths to be demultiplexed (or multiplexed) using a single wavelength multiplexer/demultiplexer. It is in.

The Ω demultiplexer of the present invention includes a focusing rod lens whose refractive index changes in the radial direction from the center in a square distribution approximation, an amorphous semiconductor film attached to one end surface of the rod lens, and other components of the rod lens. The rod lens is provided with a plurality of input and output parts coupled to the end face, and the amorphous semiconductor film is formed with a diffraction grating by interference fringes, etc., so that the light reflection angle at the end face of the rod lens is made different with respect to the wavelength. Features.

Note that the wavelength multiplexer/demultiplexer referred to herein also includes a wavelength multiplexer/demultiplexer that multiplexes light of multiple wavelengths.Next, the present invention will be described in detail with reference to the drawings.

FIG. 2 is a perspective view showing an embodiment of the present invention, in which a surface 6 is optically polished and an amorphous semiconductor film 7 is formed on the end surface 6.
is deposited. The amorphous semiconductor film 7 is made of, for example, an As-8-based material or an As-Se-8-(3e-based material), and when it is irradiated with light of a wavelength near the absorption edge, microscopic structural changes occur. The refractive index changes. For example, by writing interference fringes of Ar laser light onto the amorphous semiconductor film 7, the refractive index changes at regular intervals to form the diffraction grating 8. Therefore, the reflection angle at the end surface 6 of the rod lens 5 differs depending on the wavelength.Wavelength λ1.λ3.λ
This is because the angles that satisfy the black condition for , are different. And the wavelength λ1. λ2. The incident wave 10 having three wavelengths λ is made incident on the other end face 9 of the rod lens 5 via the fiber 11.

While the incident light wave X2 propagates through the rod lens 5, the beam diameter expands, irradiates the beam between positions 71 and 72 on the diffraction grating B, and is reflected by the diffraction grating 8. Its reflection angle is wavelength λ, λ2 . Since the light waves λ, are different from each other, the reflected light waves 22, 32, and 42 are focused at different positions on the end face 9 as shown.

A fiber 21, 31° 41 is coupled to each focusing position, and a wavelength λ1 . λ,.

An optical signal of λ is extracted. In other words, it is demultiplexed.

Since each demultiplexed output is taken out in parallel from different positions on the end face 9, it is possible to demultiplex multiple wavelengths with a single demultiplexer, eliminating the need to combine multiple units in multiple stages as in the past. , m wavelengths are easily separated by m fibers. The configuration of this embodiment is simple;
It can be provided at a low cost without requiring any assembly work or the like. Note that in order to multiplex light of a plurality of wavelengths, it can be realized by using the exact same configuration as described above and using opposite optical paths. That is, it goes without saying that it can also be used as a wavelength multiplexer. Also,
In the above embodiment, the input and output sections are the fibers 11, 21,
31, 41, etc. are coupled to the rod lens end surface 9, the same effect can be achieved even if other input/output means, such as a lens, are used.

As described above, in the present invention, an amorphous semiconductor film is attached to one end surface of the rod lens, and a diffraction grating is written on the amorphous semiconductor film to make the reflection angle different for each wavelength. Multiple people and an output section are provided on the other end of the lens, and the structure is configured so that light of a specific wavelength is transmitted and received between the multiple people and the output section, so it is possible to separate or combine multiple wavelengths with one component. is possible. In other words, it can be provided in a small size and at low cost.
Moreover, it has the effect of reducing the number of assembly steps.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an example of a conventional wavelength multiplexing/demultiplexer, and FIG. 2 is a perspective view showing an embodiment of the present invention. In the figure, 1 to 3...min σν/multiple unit, 4/min.
... Optical path conversion unit, 5... Rod lens, 6, 9
... End face of rod lens, 7... Amorphous semiconductor film, 8... Diffraction grating, 10... Incident wave, 11, 2
1゜31.41...Fiber. Agent Patent Attorney Resident 1) Sosou

Claims (1)

[Claims] A focusing rod lens whose refractive index changes in the radial direction from the center in a square distribution approximation, an amorphous semiconductor film attached to one end surface of the rod lens, and a plurality of preconcentrations bonded to the other end surface of the rod lens. , and an output section, wherein a diffraction grating is formed on the amorphous semiconductor film by interference fringes or the like so that the light reflection angle at the end face of the rod lens is made different with respect to the wavelength. .