JPH04320375A - Optically driven semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the quantity of light from lowering by forming an optical transmission path between a light source and a semiconductor element of a single optical fiber having no joint. CONSTITUTION:Two laser diode modules 11, 12 are respectively coupled with long optical fibers 71, 72 of several tens of meters through incident connectors 21, 22 and both optical fibers 71, 72 are extending upto outlet connectors 44 coupled with the light receiving part of an optical thyristor 6. The optical fibers 71, 72 are step index type fibers having good transmission characteristics composed of silicon or multi-component glass which satisfy the conditions of considerably high optical power and heat resistance. Furthermore, a rod lens is inserted between a light source 10 and the connector 21 in order to converge the laser beam thus increasing the quantity of light incident to the optical fiber 71.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-driven semiconductor device that is equipped with a plurality of light sources for driving light-driven semiconductor elements such as optical thyristors and employs a light source redundancy system.

0002

[Prior Art] In an optically driven semiconductor device that uses an optical thyristor to facilitate isolation between a high-voltage primary circuit and a control circuit, the signal for turning on the optical thyristor is usually transmitted through a light emitting diode or a laser diode. The light from such light sources is guided through optical fibers. In order to operate at high voltage, it is common to use multiple optical thyristors connected in series. In order to simultaneously turn on a plurality of optical thyristors connected in series in this manner, a considerably large optical power is required to overcome the firing variations of the optical thyristors, and this is also an absolute condition.

[0003] Thyristors are required to have a long service life in order to stabilize power supply and ensure reliability. However, since there are few light sources for ignition that have a long lifespan, a light source redundancy system is adopted in which a plurality of light sources are used and a spare light source is always on standby. FIG. 2 shows, for example, two light sources known in Japanese Unexamined Patent Publication No. 61-203678.
The configuration of the redundant system is shown below. In this case, optical fibers 31 and 32 having a core diameter of 100 μm, for example, are connected to the two laser diode modules 11 and 12 via incident-side connectors 21 and 22, respectively, and each has a cross section shown in FIG. 3(a). The two fibers 31 and 32 are combined into one fiber by a fusion technique just before the output side connector 41, resulting in a cross section 3 as shown in FIG. 3(b).
A 2-to-1 fiber with 3 is formed. The output side connector 41 is coupled to the input side connector 43 via a 2-core-1-core connector 42, and guides light to a long fiber 5 having a core diameter of 200 μm, for example, whose cross section is shown in FIG. 3(c). The light guided to the long fiber 5 is guided from the output side connector 44 to the optical thyristor 6.

In such a redundant system, it is assumed that the light source 11 is initially operating the system. When the optical output of this light source 11 decreases, there is insufficient optical power to overcome the firing variations of the plurality of optical thyristors connected in series, making it impossible to turn on each optical thyristor at the same time, making it difficult to ignite the light. The voltage of the thyristor jumps. The purpose of light source redundancy is to detect this voltage jump and switch to a standby light source 12 to prevent system failure.

[0005]

However, in the redundant system, since there are several coupling points between the light sources 11 and 12 and the optical thyristor 6, a loss occurs at each coupling point, and the light receiving element receives a loss. The final light intensity is 30% of the initial light intensity.
It also decreases. Among these, the points where particularly large losses occur are the point where the two light source side fibers 31 and 32 are fused just before the output side connector 41, the 2-core to 1-core connector 42, and the long fiber input side connector 43. It is the coupling point between the
This results in a total of 5 dB (30%). This reduction in light intensity cannot overcome the firing variations of multiple optical thyristors connected in series, leading to a voltage jump at turn-on, which in turn leads to voltage breakdown of the light receiving element, and ultimately leads to equipment failure. It has drawbacks including the risk of system failure.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optically driven semiconductor device which eliminates the above-mentioned drawbacks and prevents a decrease in the amount of light from a light source to a light receiving element when a redundant optical transmission system is employed. .

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a light-driven semiconductor device that employs a redundant system including a plurality of light sources to drive one light-driven semiconductor element. In the apparatus, it is assumed that the optical transmission path between the light source and the semiconductor element is composed of a single optical fiber that is not coupled in the middle. Furthermore, it is effective to provide a connector that faces the light receiving section of the optically driven semiconductor element and is commonly coupled to each optical fiber. A laser diode can be used as the light source, and an optical thyristor can be used as the optically driven semiconductor element. It is also effective to interpose a rod lens between a laser diode as a light source and a connector coupled to an optical fiber.

[0008]

[Operation] Only one optical fiber exists in the transmission path between each light source and the optically driven semiconductor element, and there is no coupling point in the middle, so there is no coupling loss except at the fiber end, and large optical power is generated. Can be secured.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to figures in which parts common to those in FIG. 2 are given the same reference numerals.

FIG. 1 shows the entire redundant optical transmission system in one embodiment of the present invention, in which two laser diodes (
LD) Long optical fibers 71 and 72 of several tens of meters are connected to the modules 11 and 12 via input side connectors 21 and 22, respectively, and both optical fibers 71 and 72 are connected to each other.
extends as it is to the output side connector 44 coupled to the light receiving section of the optical thyristor 6. Optical fibers 71, 72
Since a considerably large optical power is required and heat resistance is an issue, step-index type fibers with good transmission characteristics and made of quartz or multi-component glass are used. FIGS. 4(a) and 4(b) show the optical fiber 71
, 72, and the fibers 71, 7 shown in Figure (a) are separated near the input side connectors 21, 22.
2 are in close contact with each other in the vicinity of the output side connector 44 as shown in Figure (b).

The diameters of the optical fibers 71 and 72 are selected taking into consideration ease of handling or a small minimum bending radius for constructing a system. In this embodiment, the light emitting surface length of the LD is 400 μm, while the core diameter of the optical fibers 71 and 72 is 200 μm, which is the maximum dimension currently available. However, compared to the optical fibers 31 and 32 having a core diameter of 100 μm in the conventional example shown in FIG. 2, it is much easier to allow light to enter the fibers. Furthermore, Figure 5 shows LD module 1.
1 LD element 10, connector 21, optical fiber 71
As shown in FIG. 1, a rod lens 8 is inserted between the light source 10 and the connector 21, and increases the amount of light incident on the optical fiber 71 by constricting the laser light. Figure 6 (
a) to (f) are rod lenses 81 of various shapes,
82, 83, 84, 85, and 86 are shown, and as is clear from the figure, 81 is rod-shaped, 82 has a single-sided lens, and 8
3 has a double-sided lens, 84 has a conical shape, 85 has a conical shape with a single-sided lens, and 86 has a conical shape with a double-sided lens.The shape of the rod lens is also selected to coordinate with the length of the light emitting surface of the LD of the light source. , the diameters of the optical fibers 71 and 72 used can be changed.

Comparing the embodiment shown in FIG. 1 with the conventional example shown in FIG. 2, in the case of FIG. The light source 11 in the case of FIG.
, 12 and optical fibers 31, 32, optical fibers 31,
32 to the optical fiber 33, light source side fiber 33
This was reduced by half compared to the four locations of long fiber 5, long fiber 5, and optical thyristor 6. In this way, by optimizing the core diameter of the optical fiber, the loss at the input part to the fiber is reduced, and the coupling loss is reduced, resulting in a system transmission loss of 1.
．． 5 dB, which is 70% of the initial light intensity and 2 dB compared to the conventional one.
More than double the amount of effective light can be obtained.

[0013]

[Effects of the Invention] According to the present invention, coupling loss is reduced by using one optical fiber without an intermediate coupling part as the optical transmission path from a plurality of light sources to one optically driven semiconductor element. At the same time, the fiber diameter can be selected from a wider range, making it possible to effectively utilize the amount of light from the light source, and improving the overall transmission loss. This is extremely effective in improving the long-term reliability of, for example, a high voltage control device in which a plurality of optical thyristors are connected in series.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a light-driven semiconductor device according to an embodiment of the present invention.

[Figure 2] Configuration diagram of a conventional optically driven semiconductor device

[Figure 3] Cross-sectional view of each part of the optical transmission system in the semiconductor device in Figure 2

[Figure 4] Cross-sectional view of each part of the optical transmission system in the semiconductor device in Figure 1

[Figure 5] Cross-sectional view of the light source section of the semiconductor device in Figure 1

[Figure 6] Side view showing various shapes of rod lenses

[Explanation of symbols]

10 Laser diode (LD) element 11
LD module 12 LD module 21 Connector 22 Connector 44 Connector 6 Optical thyristor 71 Optical fiber 72 Optical fiber 8 Rod lens

Claims (5)

[Claims] Claim 1: In a redundant system including a plurality of light sources for driving one optically driven semiconductor element, the optical transmission path between the light source and the semiconductor element is a single optical transmission path that is not coupled in the middle. A light-driven semiconductor device comprising an optical fiber. 2. The optically driven semiconductor device according to claim 1, further comprising a connector that faces the light receiving section of the optically driven semiconductor element and is commonly coupled to each optical fiber. 3. The optically driven semiconductor device according to claim 1, wherein a laser diode is used as the light source. 4. The optically driven semiconductor device according to claim 3, wherein a rod lens is interposed between the laser diode serving as the light source and the connector coupled to the optical fiber. 5. The optically driven semiconductor device according to claim 1, wherein an optical thyristor is used as the optically driven semiconductor element.