JPH058951U - Light modulator - Google Patents

Abstract

(57) [Summary] [Object] To provide an optical modulation element that is modulated by a magnetic field, is capable of high-speed modulation, and is easily downsized. A light modulating element including at least a semiconductor laser or a light emitting diode, a hall element 2 receiving a signal magnetic field from the outside, and a voltage-current conversion according to the output of the hall element into one light modulating element. 1 is provided with a field effect transistor 3 for changing the drive current.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an optical modulator used for optical information processing and optical communication.

[0002]

[Prior Art]

 Conventionally, as a method of modulating the light intensity, a method of directly changing the drive current of the light emitting element and a method of performing the intensity modulation of the light output from the light emitting element using an acousto-optical element or the like have been mainly used.

[0003]

[Problems to be solved by the device]

 However, when changing the drive current directly, especially when high-speed modulation is required, it is necessary to carefully consider the wiring pattern inside and outside the optical modulator in order to improve noise resistance. In addition, when using an acousto-optic device, it is necessary to dispose and design optical components such as a lens, and there is also a problem that the shape of the light modulation device becomes large.

In view of the above points, the present invention has an object to provide an optical modulation element capable of high-speed modulation and easily miniaturized.

[0005]

[Means for Solving the Problems]

 The light modulation element of the present invention comprises a light emitting element such as a semiconductor laser and a light emitting diode, a hall element that receives a signal magnetic field from the outside, and a field effect transistor that changes the drive current of the light emitting element according to the output of the hall element. It is characterized by comprising.

[0006]

[Action]

 As described above, the present invention uses a Hall element whose output potential changes by an external signal magnetic field and a field effect transistor as a voltage-current conversion element that operates at high speed, and modulates light at high speed. In addition, it is possible to obtain an optical modulator that is easy to miniaturize without requiring other optical parts.

[0007]

【Example】

 FIG. 1 is a basic configuration diagram showing an embodiment of the present invention. A light-emitting element 1 such as a semiconductor laser or a light-emitting diode, a Hall element 2 that receives a signal magnetic field from the outside, and a voltage-current conversion according to the output of the Hall element 2 into the light-emitting element in one light modulation element. A field effect transistor 3 for changing the driving current of No. 1 is built in.

FIG. 2 shows a more specific example. Here, a semiconductor laser is used as the light emitting element 1. The Hall element 2 is shown by a general equivalent circuit. The output voltage of the Hall element 2 is directly input to the gate of the field effect transistor 3 to control the current flowing through the semiconductor laser 1.

When the Hall element 2 receives a modulation signal or a control signal by a magnetic field from the outside of the light modulation element, a Hall voltage corresponding to the strength of the magnetic field is generated at the output terminal of the Hall element 2. The generated voltage is input to the voltage-current conversion circuit composed of the field effect transistor 3, and the current flowing through the semiconductor laser 1 is changed according to the input voltage to perform optical modulation. That is, in the present modulation element, the optical output changes and is optically modulated by the change in the magnetic field strength given from the outside of the element.

When the output of the Hall element 2 is small and the current required to drive the light emitting element 1 is large, it is possible to combine the field effect transistors 3 in multiple stages to form an amplifier circuit.

FIG. 3 is a plan view of an integrated optical modulator in which the semiconductor laser 1, the Hall element 2 and the field effect transistor 3 of FIG. 2 are integrally incorporated in the submount substrate 4.

The semiconductor laser 1, the hall element 2 and the field effect transistor 3 described above can be formed of the same type compound semiconductor, which is useful because the size can be reduced, the reliability can be improved, and the cost can be reduced. For example, as the semiconductor laser 1, a semiconductor laser having a VSIS structure, in which GaAs is used as a substrate and a V-groove is formed in the substrate to limit a region in which an electric current flows, is well known. is there. As the Hall element 2, there is one in which ions are directly implanted into a GaAs substrate to form an active layer. As the field effect transistor 3, a structure of a planar MES • FET using GaAs as a substrate is known.

Further, since the same GaAs is used as the substrate, the semiconductor laser 1, the Hall element 2 and the field effect transistor 3 may be incorporated and integrated in one GaAs substrate.

As described above, the optical modulator of this example can modulate the optical output depending on the strength of the magnetic field. And high-speed response is possible. In other words, the modulation speed limit is low in the conventional modulation circuit in which electrical wiring is provided outside the element, but in this example, the electrical part of the modulation circuit is configured inside the element and the modulation signal or control signal is provided. Since there is no external wiring or external terminals, the magnetic field changes directly from the external space, so speedup can be easily achieved. Moreover, since no acousto-optic element is used, it is possible to reduce the size, improve reliability, and reduce cost.

Further, since a modulation signal is sent by radio, which is a change in magnetic field, a large number of optical modulation elements can be driven at one time, and the number of elements can be easily increased or decreased.

[0016]

[Effect of the device]

 As described above, the optical modulator of the present invention uses a Hall element whose output potential changes by an external signal magnetic field and a field effect transistor as a voltage-current converter that operates at high speed. Thus, it is possible to provide a light modulation element that can modulate light and that can be easily downsized without the need for other optical parts.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram showing an embodiment of the present invention.

FIG. 2 is an electric circuit diagram showing the same example.

FIG. 3 is a plane structure diagram showing an example of the same.

[Explanation of symbols]

 1 Light emitting element 2 Hall element 3 Field effect transistor

Claims (1)

[Claims for utility model registration] 1. A light emitting element such as a semiconductor laser or a light emitting diode, a hall element that receives a signal magnetic field from the outside, and an electric field that changes the drive current of the light emitting element according to the output of the hall element. An optical modulator comprising an effect transistor.