JPS62150308A - Light emitting element with optical fiber - Google Patents

Abstract

PURPOSE:To obtain an optical transmitter having an excellent performance by fixing an optical fiber by a supporting body which has been brought to bending to a prescribed shape, in a light emitting element. CONSTITUTION:In a supporting body 8 which has been brought to bending to a prescribed shape, an optical fiber 5 is inserted and fixed, and it is fixed to a light emitting diode in a connecting part 4. The optical fiber 5 is inserted into the supporting body 8 consisting of a copper pipe, and thereafter, the supporting body is brought to bending, and it is aligned and fixed by using a usual fine motion base so that an optical output becomes maximum, to a light emitting part of the light emitting diode. In this state, the optical output being equal to an optical output when a conventional light emitting element with an optical fiber has been used linearly is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Object of the Invention) The present invention relates to a light emitting element that converts an electrical signal into light, which is essential in communication systems using optical fibers and in the field of optical measurement.

(Prior art) Light-emitting elements include single elements (Fig. 2) and those integrated with optical fibers (commonly known as pigtail type - Fig. 3).
and so on.

Among the single light emitting elements shown in Figure 2, a light emitting element that converts an electrical signal into light (e.g. a light emitting diode, a laser, etc.)
A chip is housed in a package 2 having a light transmission window 1, and an electric signal applied from the electric current tm3.3' is converted into light and taken out from the light transmission window 1.

For example, as shown in FIG. 3, the light emitting element with optical fiber is
A light emitting element and an optical fiber 5 are fixed and integrated at a connecting portion 4. By integrating it with an optical fiber in this way, it becomes possible to extract light in any direction by utilizing the flexibility of the optical fiber, making layout and handling easier when implementing it into an optical transmitter, etc. .

In a small optical transmitter, as shown in FIG. 4, a light emitting element with an optical fiber is housed and mounted in an outer box 6 together with other electronic circuit components 9. After winding it into a loop shape one or more times, the end of the optical fiber is connected to the optical connector 7 or taken out to the outside of the outer box 6 without going through the optical connector (not shown in the figure).

The reasons for winding the optical fiber into a loop in this way are that it is easier to work if the optical fiber has a certain length for mounting purposes, it is convenient to repair the optical fiber in the event that it breaks, and it is also This includes allowances for expansion and contraction of various parts due to fluctuations in ambient temperature when the transmitter is in use. The external dimensions of a compact optical transmitter are generally from several tens of millimeters to about 100 to 200 millimeters. When a light emitting element with an optical fiber is incorporated into an optical transmitter having such external dimensions, the above-mentioned optical fiber loop has a bending radius of 10 mm to 10 mm.
It will be about 0mm.

Conventionally, this type of light emitting element with optical fiber was assembled by aligning the optical fiber with the light emitting part of the light emitting element in a substantially straight or gently bent state and fixing it at the position where the light output was maximized. It is being said.

When the optical fiber aligned and fixed in this condition is actually used, the diameter is 10 mm to 10 mm, as mentioned earlier.
In other words, it is bent with a small radius of curvature of about 0 to 200 mm.

By the way, in the conventional light-emitting element with optical fiber shown in FIG. 3, when the optical fiber is bent near the connection part 4 between the optical fiber 5 and the light-emitting element, the light output of the light-emitting element depends on the radius of curvature R. The measurement results revealed that the Based on the optical output when the optical fiber is straight, the decrease in optical output when the optical fiber is bent with a radius of curvature R is the excess loss (dB), and the excess loss is the reciprocal of the curvature/radius R. The relationship with loss is shown in Figure 5.

In other words, curvature/radius 3Qiun is 0.5dB, 20m
An excess loss of 1 dB occurs at m. This value is a non-negligible value compared to the loss occurring in connections between optical fibers and optical connectors, and poses a problem in terms of the performance of the optical transmitter and the design of the optical transmission system using it.

(Problems to be Solved by the Invention) The present invention has been made based on the following considerations regarding the cause of the occurrence of excessive loss as described above.

In other words, when an optical fiber is bent near its end face, the angle of incidence and acceptance of light that can enter from the end face deviates from the angle of incidence when the optical fiber is straight. When the optical fiber is bent, the amount of light that enters the optical fiber from the light emitting element is smaller than when the optical fiber is straight. The smaller the radius of curvature of the optical fiber is bent, the larger the deviation in the angle of incidence and reception becomes. Therefore, the smaller the radius of curvature of the optical fiber is, the greater the apparent reduction in the optical output of the light emitting element, that is, the greater the excess loss.

(Means for Solving the Problems) The present invention solves these problems and provides an optical system that does not cause excessive loss when the optical fiber is bent and mounted, and that allows the maximum optical output of the light emitting element to be obtained. The object of the present invention is to provide a fiber-equipped light emitting device and a method for manufacturing the same, and has the following characteristics.

(Function) The light emitting device with an optical fiber of the present invention includes a light emitting device that converts an electrical signal into light and an optical fiber that guides light to the light emitting device, in which the optical fiber is bent into a predetermined shape. It is characterized in that it is fixed with a fixed support.

Further, it is characterized in that an optical fiber fixed to a support body previously shaped into a predetermined shape is fixed and aligned with respect to the light emitting part of the light emitting element.

(Embodiment) FIG. 1 is an outline drawing showing one embodiment of a light emitting device with an optical fiber according to the present invention.

In FIG. 1, a support 8 is bent into a predetermined shape.
An optical fiber 5 is inserted into and fixed to the light emitting diode at the connecting portion 4.

The support 8 was a copper pipe with an inner diameter of 1 mm, an outer diameter of 2 mm, and a length of 80 mm, and the optical fiber 5 was of a graded index type with a core diameter of 50 μm, a cladding diameter of 125 μm, and a percent NA of 0.2.

After the optical fiber 5 is inserted into the support 8 made of a copper pipe, it is bent with a radius of curvature of 20 mm, and then it is bent in a normal manner so that the light output is maximized for the light emitting part of the light emitting diode with a diameter of 20 μm. It was aligned and fixed using a fine movement table. In this state, a light output equivalent to that obtained outside the field using a conventional light-emitting element with an optical fiber in a straight line was obtained.

A copper pipe was used as a support because it has a moderate amount of flexibility and is easy to bend, and because it slides easily between the optical fiber and the optical fiber during bending!・The reason is that there is little risk of applying excessive force to the binary fiber.

The radius of curvature of the bending process was set to 20 mm in accordance with the dimensions of the case of the optical transmitter in which this light emitting element with optical fiber is used. This radius of curvature can be made even smaller, but if it is bent with a small radius of curvature of 20 mm or less, there is a risk that the optical fiber's characteristics will deteriorate or break during long-term use due to the bending stress applied to the optical fiber itself. becomes higher.

Therefore, it is appropriate that the radius of curvature is 20 mm or more.

On the other hand, it goes without saying that it is possible to have a surface area radius of 200 mm or more, but if the radius of curvature is large, there is almost no decrease in optical output even in conventional linear light-emitting elements with optical fibers that are aligned and fixed. This is not a subject of the present invention because there is no such thing and there are few advantages in terms of implementation.

A radius of curvature of 70 mm or less is effective from the viewpoint of preventing excessive loss and mounting in a compact optical transmitter.

(Effects of the Invention) As described above, since the optical fiber-equipped light emitting device of the present invention uses a pre-bent optical fiber that is aligned and fixed with respect to the light emitting diode, the incident acceptance angle caused by the bending of the optical fiber is The light emitting diode will be aligned in accordance with the change in .

Therefore, the maximum light output can be obtained even when the optical fiber is in a sharp bend when installed in a small optical transmitter, etc., so the optical performance is superior to that when using a conventional light emitting element with an optical fiber. A transmitter can be configured. In addition, as a side effect of the optical fiber being protected by the support, there is no need to apply excessive force to the mechanically weak connections 4 and the vicinity during mounting, thereby preventing unexpected damage to the optical fiber. Another advantage is that accidents can be prevented.

As described above, the optical fiber-attached light emitting device of the present invention is particularly useful as a light emitting device used in small optical transmitters and the like.

In the examples, a copper pipe was used as the support, but the material is not limited to copper, and any material such as stainless steel, aluminum, ceramic, plastic, etc. can be used.

Furthermore, its shape is not limited to a pipe, but may be a flat plate, a template with a concave cross section, a polygonal rod, or any other shape as long as it can support and fix the thin optical fiber. .

[Brief explanation of drawings]

Fig. 1 is an external view showing an embodiment of a light emitting element with an optical fiber according to the present invention, Fig. 2 is an external view of the light emitting element, and Fig. 3 is an external view showing an example of a conventional light emitting element with an optical fiber. FIG. 4 shows an example of mounting a light emitting element with an optical fiber in a small optical transmitter, and FIG. 5 shows actual measurement results regarding the relationship between the bending radius of the optical fiber and excess loss. l Light transmission window 2 Package 3.3' Electrode 4, contact, branch 5 Optical fiber 6 Optical transmitter outer box 7 Optical connector 8 Support body 9.10.11 Electronic circuit components 7γ!

Claims (4)

[Claims] (1) In a light emitting device consisting of a light emitting device that converts an electrical signal into light and an optical fiber that guides light to the light emitting device,
A light emitting element with an optical fiber, characterized in that the optical fiber is fixed to a support body bent into a predetermined shape. (2) The optical fiber according to claim 1, characterized in that the optical fiber is fixed to a support body that has been bent into a predetermined shape in advance and is aligned and fixed to the light emitting part of the light emitting element. A method for manufacturing a light emitting element with a light emitting device. (3) The radius of curvature of the optical fiber fixed on the support is 20
The light emitting device with an optical fiber according to claim 1, characterized in that the length is from mm to 70 mm. (4) A light emitting device with an optical fiber according to any one of claims 1 to 3, wherein the support body is made of a copper pipe, and an optical fiber is inserted and fixed into the copper pipe.