JPS6375712A - Detector element for optical fiber - Google Patents

Abstract

PURPOSE:To eliminate the need for the space of the conventional photodetector and to reduce the manufacturing cost by forming a photodetector directly on the end face of an optical fiber by a thin film forming technique. CONSTITUTION:The photodetector 4 is formed directly on the end face of the optical fiber 1 by the thin film forming technique. The photodetector 4 is obtd. by forming 50OMEGA strip lines 5, 5' on the end face of the optical fiber 1 via a gap (b) interposed therebetween and forming an a-SiGe film 6 to about 1,000Angstrom thereon by a plasma CVD method and further forming an earth electrode 7 thereon over the entire surface. A signal can be taken out at a high speed of several tens - several PS from the other of the lines 5, 5' when several tens V voltage is impressed to one thereof. The need for the conventional photodetector is, therefore, eliminated and the manufacturing cost is reduced.

Description

[Detailed Description of the Invention] [Summary] A detector for optical fiber, which includes a -
By providing a high-speed optical detection element using a SiGe film, it is possible to reduce the size and manufacturing cost.

[Industrial application field]

The present invention relates to an optical fiber detector used in optical communication devices and the like.

In optical communications, demands for high speed, multiplex communication, etc. require photodetectors with fast optical response and wide wavelength bandwidth.

[Conventional technology]

Conventionally, an a-SiGe (amorphous silicon germanium) film, which has a smaller bandgap than an a-3T film and a higher defect density, has been used as a photodetector element with a high speed (photoresponsivity of several PS) and a wide wavelength bandwidth. Some were extended to about 1 μm.

[Problem that the invention seeks to solve]

The above-mentioned conventional optical detection element has problems in that it is expensive and a space must be secured to accommodate it because it is manufactured as a single optical detection element.

The present invention was created with these points in mind, and an object of the present invention is to provide a detection element for an optical fiber that is inexpensive and does not require space for accommodation.

[Means for solving problems]

Therefore, in the present invention, as illustrated in FIG.
It is characterized in that the optical detection element 4 is formed on the end face of the optical fiber 1 by thin film technology.

[For production]

Since the optical detection element 4 is formed directly on the end face of the optical fiber by the thin hole drilling technique, it can be made at low cost and there is no need to secure a housing space.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention, in which a is a front view;
b is a cross-sectional view taken along line bb in figure a.

In this embodiment, as shown in FIG. 1, a core 2 with a large refractive index
Optical fiber 1 consists of a (several tens of μm in diameter) and a cladding 3 (100 to 200 μm in diameter) with a smaller refractive index than the core.
A photodetecting element 4 using an a-SiGe film is provided on the end face of the optical fiber 1.
A 0Ω stripline 5°5′ is formed with a gap g, and a strip line with a thickness of about 100Ω is formed on it by plasma CVD.
0 a-SiGelJ 6 is formed, and a ground electrode 7 is further formed on the entire surface thereof.

In this embodiment formed in this way, the strip line 5,
It is possible to apply a voltage of several tens of µm to one side of 5' and extract a signal from the other side. According to this embodiment, it is possible to operate at a high speed of several tens to several PS, and since it is formed on the end face of an optical fiber, it can be manufactured at low cost and requires almost no space for accommodating the element.

FIG. 2 is a diagram showing another embodiment of the present invention, in which a is a front view and b is a sectional view taken along line bb in FIG.

This embodiment differs from the previous embodiment in that the order of formation of the strip lines 5, 5', a-SiGe film 6, and ground electrode 8 is completely reversed, and that the ground electrode 7 blocks light from the optical fiber 1. The ground electrode 7 is formed of a transparent conductive film in order to prevent it from being blocked. The present embodiment configured in this manner has the same effects as the previous embodiment, and has the advantage that since the strip lines 5 and 5' are formed externally, wiring with the signal processing circuit is easy. .

〔Effect of the invention〕

As described above, according to the present invention, there is no need to secure a space for a conventional photodetector, and the manufacturing cost can be reduced, so that it is useful even in practical applications.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the invention, and FIG. 2 is a diagram showing another embodiment of the invention. 1 and 2, 1 is an optical fiber, 2 is a core, 3 is a cladding, 4 is a photodetecting element, 5.5' is a strip line, 6 is an a SiGe film, and 7 is a ground electrode. (a) (b) Diagrams showing embodiments of the present invention Fig. 1 Optical fibers 5, 5'... Strip line 4... Optical detection element (a) (b) Other embodiments of the present invention Figure 2 shows Figure 3... Clad 7... Earth electrode 4... Optical detection element

Claims (1)

[Claims] 1. A detection element for an optical fiber, characterized in that an optical detection element (4) is formed on the end face of an optical fiber (1) by a thin film forming technique. 2. The detection element (4) is made of a-SiGe with a small absorption edge.
2. The optical fiber detection element according to claim 1, which uses a film and has a gap cell structure.