Light emitting device and method for controlling light emitting device

Abstract

To suppress heat generation in a light-emitting device used in outer space.SOLUTION: A light emitting device 10 includes a laser diode 110, a current detection unit 120, and a control unit 130. The current detection unit 120 detects, in real time, a current flowing through the laser diode 110. The control unit 130 performs pulse width modulation control of the current flowing through the laser diode 110 such that a current value detected by the current detection unit 120 becomes a target value. The light emitting device 10 is, for example, a part of an optical amplifier.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a light emitting device and a method for controlling a light emitting device. [Background technology]

[0002] Diodes, which are a type of light-emitting element, are used in a variety of applications. For example, Patent Document 1 describes pulse-width modulation control of a diode used as an excitation light source for a fiber laser device for processing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-167383 Summary of the Invention [Problem to be solved by the invention]

[0004] Laser diodes are one type of diode. Light-emitting devices equipped with laser diodes are sometimes used in outer space. In such cases, it is difficult to dissipate heat into outer space, so it is desirable to suppress heat generation from the light-emitting device. [Means for solving the problem]

[0005] According to one aspect of the present invention, there is provided a light emitting device for use in outer space, comprising: A laser diode; a current detection unit that detects a value of a current flowing through the laser diode; a control unit that performs pulse width modulation control of the current flowing through the laser diode based on the difference between the current value and a target value; A light emitting device is provided, comprising:

[0006] According to one aspect of the present invention, there is provided a method for controlling a light emitting device used in outer space, comprising the steps of: The value of the current flowing through the laser diode is detected using a current detection unit, A control method for a light emitting device is provided, in which a control unit is used to pulse width modulate the current flowing through the laser diode based on the difference between the current value and a target value. [Effects of the Invention]

[0007] According to one aspect of the present invention, heat generation can be suppressed in a light-emitting device used as part of an optical amplifier used in outer space. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a configuration of a light emitting device according to an embodiment. [Figure 2] 10 is a graph showing the relationship between the current flowing through a laser diode and the light emitting efficiency of a light emitting device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, like components are designated by like reference numerals, and the description thereof will be omitted as appropriate.

[0010] FIG. 1 is a diagram showing an example of the configuration of a light emitting device 10 according to an embodiment. The light emitting device 10 is used in outer space. As an example, the light emitting device 10 is used as part of an optical amplifier. This optical amplifier is mounted on, for example, a satellite and used for optical communications between satellites or between a satellite and the ground. The communication distance is, for example, several kilometers to several hundred kilometers. Therefore, the light emitting device 10 is required to have a high amplification factor. On the other hand, in outer space, it is difficult to dissipate heat from the light emitting device 10, so the light emitting device 10 is required to generate a small amount of heat. The amplification factor of the light emitting device 10 is, for example, 2000 times or more.

[0011] The light-emitting device 10 includes a laser diode 110, a current detection unit 120, and a control unit 130. The current detection unit 120 detects the current flowing through the laser diode 110 in real time. The control unit 130 controls the pulse width modulation of the current flowing through the laser diode 110 so that the current value detected by the current detection unit 120 becomes a target value. When the light-emitting device 10 is part of an optical amplifier, the target value used by the control unit 130 is determined, for example, using the intensity of light incident on the optical amplifier and a desired amplification factor.

[0012] As described above, the light emitting device 10 is required to have a high amplification factor, i.e., high output, and stable light output. For this reason, the current flowing through the laser diode 110 is a stabilized constant current, and the maximum value of this constant current may be, for example, 5 A or more, or even 10 A or more, or even 15 A or more.

[0013] The control unit 130 includes a switch 132, a comparator 134, and an oscillator 136, and controls the current flowing through the laser diode 110 by pulse width modulation (PWM). The switching frequency used for this PWM control is, for example, 400 kHz or higher. By setting the switching frequency in this way, the laser diode Since the laser diode 110 cannot follow this switching frequency, it is possible to suppress fluctuations in the light emission intensity of the laser diode 110 caused by PWM control. In the light emitting device 10, the magnitude of these fluctuations is suppressed to, for example, 0.5% or less.

[0014] The comparator 134 compares the target value of the current flowing through the laser diode 110 with the current value detected by the current detection unit 120, and uses the comparison result to control the oscillator 136. The switch 132 turns on and off in accordance with the oscillation signal input from the oscillator 136.

[0015] 2 is a diagram showing the relationship between the current flowing through laser diode 110 and the light emission efficiency of laser diode 110. As shown in this diagram, when the current flowing through laser diode 110 is 3 A, the light emission efficiency is 85% or more, and when this current is 5 A or more, the light emission efficiency becomes 90% or more. When the current is 20 A, the light emission efficiency also becomes 90% or more.

[0016] For reference, in a typical optical amplifier used in outer space, the laser diode is controlled by a linear control method. In this method, a current control element is used instead of the switch 132 and the comparator 134. In this case, the light-emitting efficiency is about 70%. Since most of the power loss is converted into heat, if this loss is large, a large heat sink for heat dissipation is required. In contrast, the light-emitting device 10 according to this embodiment has small loss, so there is no need to provide a heat sink for heat dissipation, or even if one is required, the heat sink can be made smaller.

[0017] In this way, by using the control unit 130, the light emitting efficiency of the light emitting device 10 is increased, thereby suppressing the amount of heat generated by the light emitting device 10. This eliminates the need to provide a heat sink for heat dissipation in the light emitting device 10. Furthermore, the fluctuation in the light intensity of the laser diode 110 can be suppressed to within 0.5%.

[0018] As described above, according to this embodiment, the light emitting efficiency of the laser diode 110 is improved. Therefore, heat generation in the light emitting device 10 can be suppressed. Furthermore, since the light emitting device 10 does not need to be provided with a heat sink for heat dissipation, the size of the light emitting device 10 can be suppressed from becoming large, and the size of the light emitting device 10 can be made smaller than a cube with sides of 10 cm, for example.

[0019] Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various other configurations can also be adopted. [Explanation of symbols]

[0020] 10. Light-emitting device 110 Laser Diode 120 Current detection unit 130 control section 132 Switch 134 Comparator 136 Oscillator

Claims

1. A light-emitting device for use in outer space, A laser diode; a current detection unit that detects a value of a current flowing through the laser diode; a control unit that performs pulse width modulation control of the current flowing through the laser diode based on the difference between the current value and a target value; A light emitting device comprising:

2. 2. The light emitting device according to claim 1, The control unit performs pulse width modulation control at a frequency of 400 kHz or more.

3. 3. The light emitting device according to claim 1, The maximum target value is 5 A or more.

4. 3. The light emitting device according to claim 1, A light emitting device that does not have a heat sink for heat dissipation.

5. A method for controlling a light emitting device used in outer space, comprising: The value of the current flowing through the laser diode is detected using a current detection unit, A control method for a light emitting device, comprising: using a control unit to pulse-width-modulate the current flowing through the laser diode based on the difference between the current value and a target value.

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