JPH0244241Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixed attenuator most suitable for single mode fiber.

In the fixed attenuator for multimode fibers currently in use, the fiber end face 1
The fiber end face 1a is tilted to avoid the influence of reflected light from the attenuator 2 deposited on the fiber. However, when a fixed attenuator with such a structure is applied to a single mode fiber, since the single mode fiber has strong polarization dependence, the amount of attenuation by the attenuation film changes depending on the polarization direction, and the fixed attenuator It is not appropriate as

The inventors of the present invention took these circumstances into consideration and devised a fixed attenuator suitable for single mode fibers.

The attenuator according to the present invention has a structure in which a spacer (for example, a ring, etc.) is inserted between the cores in which the fibers are inserted, so that the fiber spacing d is kept constant and a damping effect is provided. . This structure has the advantage that the amount of attenuation can be changed freely by simply changing the thickness of the spacer, and the manufacturing cost can be extremely low.

Furthermore, it has the excellent feature that the amount of attenuation is stable without polarization dependence.

Examples will be explained below.

FIG. 2 shows an embodiment of the present invention, in which sleeves 5 and 5' are connected using an adapter as shown in FIG. That is, in FIG. 3, the core 7 and spacer 4 are attached to the sleeve 6 in advance, and using these, the sleeves 5, 5'
combine. The connection is carried out by inserting the core 3' protruding from the sleeve 5' into the hole 6a of the sleeve 6, and by inserting the core 7 into the hole 5a of the sleeve 5.

Here, an optical fiber having the same length as the core 7 is inserted into the core 7 in advance, and a direct butt connection is made with the optical fiber inserted into the core 3.

Further, if an entrance/exit for the spacer 4 is provided on the side surface of the adapter 6, the spacer 4 can be easily arranged.

FIG. 4 shows the relationship between the optical fiber spacing (spacer thickness) and the amount of attenuation.

In the figure, the horizontal axis shows the optical fiber spacing mm, and the vertical axis shows the attenuation amount dB.

The core diameter of the fiber used in the measurement was 10 μm, the difference in curvature index was 0.2%, and a semiconductor laser that outputs a 1.3 μm laser beam was used as the light source.

As is clear from the figure, examples include 10dB, 20dB,
Each fiber spacing to obtain 30dB attenuation is
The sizes are 0.4mm, 1mm, and 2.3mm, which are sufficiently practical.

As described above, according to the present invention, it is possible to provide a fixed attenuator that is optimal for single mode fibers.

[Brief explanation of the drawing]

Fig. 1 shows a fixed attenuator for multimode fiber, Figs. 2 and 3 show a fixed attenuator for single mode fiber according to the present invention, and Fig. 4 shows the relationship between optical fiber spacing and attenuation. FIG. In the figure, 1 and 1' are optical fibers, 3, 3', and 7 are cores, 5, 5', and 6 are sleeves, and 4 is a spacer.

Claims (1)

[Claims for Utility Model Registration] A first sleeve 6 having a through hole 6a, a first core 7 inserted from one opening of the through hole 6a of the first sleeve 6, and inside the through hole 6a, a ring-shaped spacer 4 provided to face one end of the first core 7; a single mode fiber having the same length as the first core 7 inserted in advance into the first core 7; In order to insert it from the other opening of the hole 6a,
A second sleeve 5' that holds a second core 3' that holds a single mode fiber 1' protrudes from its end; A fixed attenuator for a single mode fiber, characterized by having a third sleeve 5 holding three cores at a position recessed from the end face.