JPH058957U - Optical semiconductor device - Google Patents

Abstract

(57) [Summary] [Object] To provide a photocoupler capable of bidirectional signal propagation with a small number of elements. [Structure] In an optical semiconductor device in which two chips 11 and 12 are opposed to each other to transmit an optical signal, a semiconductor laser chip is used as each of the chips 11 and 12. Light emission and light reception are shared by the chips 11 and 12, respectively.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an optical semiconductor device, and more particularly to a bidirectional type photocoupler.

[0002]

[Prior Art]

 As shown in FIG. 5, in a conventional photocoupler, a set of a light emitting element 1 and a light receiving element 2, for example, a GaAs light emitting diode and a silicon photodiode are opposed to each other, and these are molded with a resin 5 having a light transmitting property. Further, the outer periphery of the resin 5 is molded with black resin. 3 is a lead frame, and 4 is an Au wire. The light emitting element 1 emits light according to an input electric signal, and the light receiving element 2 receives this light and converts it into an electric signal for output. That is, an electric signal is once converted into an optical signal, and this optical signal is converted into an electric signal again. As a result, a signal can be transmitted from the input side A to the output side B in a state where the input side A and the output side B are electrically completely separated. Therefore, the withstand voltage between the input side A and the output side B can be made very large, and the noise on the input side A can be prevented from propagating to the output side B.

[0003]

[Problems to be solved by the device]

 However, the above photocoupler can only propagate signals in one direction from the input side A to the output side B. Therefore, when bidirectional signal propagation is performed, conventionally, as shown in FIG. 6, another set of light emitting element 1'and light receiving element 2'is prepared and signal propagation from B side to A side is performed. ing. In this case, the number of elements increases, assembly becomes difficult, and the number of terminals also increases (8), so that there is a problem that the photocoupler cannot be downsized.

Therefore, an object of the present invention is to provide an optical semiconductor device capable of bidirectional signal propagation with a small number of elements.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, an optical semiconductor device of the present invention is an optical semiconductor device in which two chips are opposed to each other to transmit an optical signal, and each of the chips is composed of a semiconductor laser chip. .

[0006]

[Action]

 In general, a semiconductor laser chip emits light as a light emitting element when a current is injected between electrodes, while it emits a current as a light receiving element although it is weak when light enters the chip. Thus, the semiconductor laser chip has the properties of both a light emitting element and a light receiving element. Therefore, when two semiconductor laser chips are arranged such that their laser light emitting points face each other, when one chip functions as a light emitting element, the other chip functions as a light receiving element, and the one chip receives light. When operating as an element, the other chip functions as a light emitting element. Therefore, a bidirectional photocoupler is constructed with a small number of elements. Specifically, when bidirectional signal propagation is performed, the number of elements is reduced from 4 to 2 and the number of terminals is reduced from 8 to 4 as compared with the conventional case.

[0007]

【Example】

 Hereinafter, the optical semiconductor device of the present invention will be described in detail with reference to embodiments.

FIG. 1 shows a block configuration of a bidirectional photocoupler according to an embodiment. As shown in FIG. 1, this photocoupler includes a pair of semiconductor laser chips 11 and 12 facing each other. Reference numerals 13, 14, 15, 16 denote lead pins. When manufacturing this photocoupler, first, as shown in FIG. 4A, the semiconductor laser chips 11 and 12 are bonded to the lead frame 19 so that the light emitting surfaces 11a and 12a face each other. Subsequently, as shown in FIG. 4B, lead wires of the semiconductor laser chips 11 and 12 are formed using the Au wires 20 and 21. After that, as shown in FIG. 4C, the semiconductor laser chips 11 and 12 are molded with a resin 22 (transparent or semi-transparent) that is transparent to the oscillation light of these chips. Thereby, an optical coupling path (optical path) is formed between the two chips 11 and 12. Further, the periphery of the resin 22 is molded with a flame-retardant black epoxy resin 22 so that ambient light does not enter. Finally, the lead frame 19 is cut to form the lead pins 13, 14, 15, 16.

In the bidirectional photocoupler thus manufactured, the semiconductor laser chips 11 and 12 have the properties of both a light emitting element and a light receiving element, so that no matter which side A or B is input a signal. , A signal can be output to the other side. That is, bidirectional signal propagation can be performed by the two semiconductor laser chips 11 and 12, and the number of elements can be reduced compared to the conventional case. Further, since the semiconductor laser chips 11 and 12 having a faster response than the light emitting diode are used as the light emitting element, the signal can be propagated at a higher speed than the conventional one.

Since the semiconductor laser chip generally has a lower light-receiving sensitivity than the photodiode, the output signal on the light-receiving side cannot be increased with the configuration of the photocoupler. Therefore, as a means for increasing the output signal, as shown in FIG. 2, a lens (or hologram lens) 25 is inserted between the A side semiconductor laser chip 11 and the B side semiconductor laser chip 12. Thereby, the optical coupling efficiency between the semiconductor laser chips 11 and 12 can be improved, and the output signal on the light receiving side can be increased. In this case, it is not necessary to accurately adjust the focus position, and there is no particular problem in assembly.

Further, as shown in FIG. 6, by inserting a resin 28 having a higher refractive index than the resin 22 between the semiconductor laser chips 11 and 12, the optical coupling efficiency can be increased.

[0012]

[Effect of the device]

 As is apparent from the above, this invention uses a semiconductor laser chip as each of the above-mentioned chips in an optical semiconductor device in which two chips are opposed to each other to transmit an optical signal. Can be used as Therefore, bidirectional signal propagation can be performed with a small number of elements.

[Brief description of drawings]

FIG. 1 is a diagram showing a block configuration of a bidirectional photocoupler according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example in which the structure of the bidirectional photocoupler is improved.

FIG. 3 is a diagram showing an example in which the structure of the bidirectional photocoupler is improved.

FIG. 4 is a diagram showing a manufacturing process of the bidirectional photocoupler.

FIG. 5 is a diagram showing a cross-sectional structure of a conventional unidirectional photocoupler.

FIG. 6 is a diagram showing a block configuration of a conventional bidirectional photocoupler.

[Explanation of symbols]

11,12 Semiconductor laser chip 13,14,15,16 Lead pin 19 Lead frame 20,21 Au wire 22 Silicon resin 23 Black epoxy resin 25 Lens 28 High refractive index resin

Claims (1)

Claims for utility model registration: 1. An optical semiconductor device for transmitting an optical signal with two chips opposed to each other, wherein each chip is a semiconductor laser chip.