JPS58199575A - Photoelectric device - Google Patents

Abstract

PURPOSE:To obtain a photoelectric device which has high coupling efficiency with an optical fiber and is not affected by the influence of radiation noise by shielding a semiconductor chip of a photoelectric element with a metal cap. CONSTITUTION:A semiconductor element chip 9 is mounted on a metal stem 10, and a metal cap 11 is provided to cover the chip 9. The cap 11 has shielding operation to protect it against electromagnetic noise. A hole 13 for coupling an optical fiber 8 is formed at the center of the cap 11. This hole 13 improves the coupling efficiency by setting it to a value equal to or less than approx. 1.5 times the core diameter of the fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoelectric device used as a light emitting or light receiving element in an optical fiber transmission system using an optical fiber with a relatively large core diameter as a transmission line.

One of the characteristics of transmission systems using optical fibers is that they are not affected by electromagnetic noise because they use light as the transmission signal. However, the photoelectric conversion sections at both ends of the transmission line, especially the optical reception sections, convert two vanes of weak light into weak electrical signals, and therefore are vulnerable to external noise. Therefore, the photoelectric conversion unit is shielded from radiation noise, which is one type of external noise, using a metal case or the like.

By the way, a simple optical fiber transmission system, for example as shown in the conventional example shown in FIG. A configuration in which the optical connectors 3 are used for coupling is used.

Even if the electronic circuit part takes measures against radiated noise 5 with the metal case 4, the photoelectric element 2 built into the plastic optical connector 3 does not take measures against noise, so the radiated noise 5 passes through the plastic optical connector 3. There is a drawback that the light enters the semiconductor chip 6 of the light emitting/receiving element 2 and causes the optical fiber transmission system to malfunction. Furthermore, in order to increase the coupling efficiency between the photoelectric element 2 and the optical fiber 1, the semiconductor chip 6 is connected to the optical fiber 1.
, the semiconductor chip 6 approaches the outer surface of the photoelectric element case 7, which has the disadvantage that it becomes even more susceptible to the effects of the radiation noise 5.

Page 3 Therefore, the present invention aims to provide an optical transmission system that combines an optical fiber with a relatively large core diameter, such as a plastic optical fiber, and an inexpensive general-spec semiconductor photoelectric device, which has high coupling efficiency with the optical fiber and reduces radiation noise. The aim is to provide an optoelectronic device that is not affected.

EMBODIMENT OF THE INVENTION Hereinafter, the present invention will be described in detail with reference to the drawings showing one embodiment thereof.

First, the configuration of an embodiment of the present invention will be described with reference to FIG. In the figure, 8 is an optical fiber, for example, the core diameter is 1
It is made of plastic optical fiber that is large in size, has a numerical aperture (N, A.) of ○, and has a strength. 9 is a semiconductor chip of a photoelectric device such as a semiconductor light emitting device or a light receiving device; 1Q is a metal stem for fixing the chip 9; 11 is a metal cap that covers and protects the chip 9;
The end face of the optical fiber 8 and the chip 9 are coupled to the front surface.
An opening 13 is provided to allow light 12 to pass through. 14 is a lead for external extraction of the chip 9, and 15 is a lead for internal connection.

The optical fiber 8 is fixed in close contact with and close to the front surface 16 of the cap 11 of the photoelectric element by, for example, an optical connector made of a plastic molded product (not shown). The distance 1 between the front surface 16 of the cap 11 and the chip 9 is set to be 1.0 or less for high coupling efficiency with the optical fiber 8, and is set to such a length that the cap 11 does not come into contact with the internal IJ-domain 15.

Next, the opening 13 of the cap 11 will be explained. Third
The figure shows the relationship between the diameter of the aperture 13 provided in the cap 11, the coupling efficiency (relative value) between the optical fiber 8 and the photoelectric element chip 9, and the relationship between the resistance to radiation noise (relative value). The optical fiber 8 used here is a plastic optical fiber with a core diameter of 1 Orrml, and the noise tolerance represents the degree of malfunction of the photoelectric element when a solenoid valve or the like is operated nearby as a noise source. .

From this characteristic diagram, it can be seen that the smaller the diameter of the aperture 13, the better the noise resistance, but the worse the coupling efficiency with the optical fiber 8. Therefore, the aperture diameter is equal to the core diameter of the optical fiber. ○The highest value is near the stagnation point.

Page 5 However, in reality, considering the deviation in the dimensions of the optical connector that connects the photoelectric element chip 9 and the optical fiber 8 and the positional accuracy of the photoelectric element chip 9, the core diameter of the optical fiber 8 is 1.5 times. Opening diameter of less than or equal to, in this illustration approximately 11.5
1 or less is suitable. Therefore, the opening 1 of the cap 11
3 is approximately 1.5 times or less the core diameter of the optical fiber 8, and an optimum diameter may be adopted depending on the required degree of noise tolerance or coupling efficiency with the optical fiber 8.

As described above, in this device, the metal cap 11 is provided to cover the semiconductor photoelectric element chip 9 mounted on the metal stem to protect it from electromagnetic noise, and the optical fiber 8 to be coupled to the metal cap 11 is Approximately 1 of the core diameter of
．． The aperture 13 with a diameter of 5 times or less is provided to improve the coupling efficiency, and the height is set such that the coupling interval between the semiconductor photoelectric element chip 9 and the optical fiber 8 can desirably be 1.0 mm or less. This also improves the coupling efficiency.

FIG. 4 shows another specific embodiment of the present invention.

Here, parts similar to those in FIG. 2 are designated with the same reference numerals on page 6. In this device, a semiconductor photoelectric element chip 9
The distance between the front surface 16 of the metal cap 11 and the front surface 16 of the metal cap 11 is, for example, 0.
6 rrm, the opening 13 of the metal cap 11 is filled with transparent glass 17, and the metal cap 11 and the metal stem 1o are welded to form an airtight structure, thereby improving the environmental resistance of the chip 9. The potential of the metal cap 1-1 and the stem 10 can be set to any potential required for noise resistance, for example, the ground potential by using a dedicated external lead 1.
8 is provided, and the chip 9 is fixed on an insulating submount 19 to electrically insulate the chip 9 from the stem 10.

As described above, according to the present invention, when an optical fiber having a relatively large core diameter and a semiconductor photoelectric device are connected using an optical connector made of a plastic molded product, the semiconductor chip of the photoelectric device can be completely connected with a metal cap. Because it is shielded, the semiconductor chip is not affected by radiation noise (electromagnetic waves) that passes through the plastic optical connector and is incident, and the S/N characteristics of the transmitted signal can be improved. Because of this, the distance between the chip and the optical fiber can be shortened, and the coupling efficiency between the optical fiber and the photoelectric element can be increased. Furthermore, since these effects can be obtained with a simple configuration and at low cost, it is possible to realize a low-cost and highly reliable optical fiber transmission system, promoting the application of optical fiber transmission equipment to consumer equipment and industrial equipment with strict price and usage conditions. It is something that can be done.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a conventional photoelectric device, FIG. 2 is a cross-sectional view of a photoelectric device according to an embodiment of the present invention, and FIG. 3 is a characteristic diagram showing the relationship between the aperture diameter, coupling efficiency, and noise tolerance. , FIG. 4 is a sectional view of a photoelectric device according to another embodiment of the present invention. 8... Optical fiber, 9... Semiconductor photoelectric element chip, 10... Metal stem, 11...
...Metal cap, 13...Open hole. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3 Open page Figure 4 369-

Claims (1)

[Claims] A semiconductor photoelectric element chip that emits light to be input into an optical fiber or receives light emitted from the optical fiber is fixed to a metal stem, and a metal cap that covers the periphery of the semiconductor photoelectric element chip is attached to the metal stem. , approximately 1.5 of the diameter of the optical fiber on the front surface of the metal cap.
A photoelectric device characterized by having an aperture with a diameter equal to or less than double that of the aperture.