Semiconductor laser device

Abstract

To provide a semiconductor laser device using a laser light-emitting element in which end face breakdown due to the flow of a large current does not occur even when a surge voltage is applied.SOLUTION: The semiconductor laser device 10 includes a laser light emitting element 11 for emitting laser light, a TVS diode 13 connected to the laser light emitting element 11 and having quick response, and a Zener diode 15 connected in parallel with the TVS diode and having slower response than the TVS diode 13.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a semiconductor laser device using a laser light-emitting element. [Background technology]

[0002] When assembling a semiconductor laser device using a laser light-emitting element, static electricity may be transmitted to the laser light-emitting element, causing electrostatic breakdown of the laser light-emitting element. Even if complete breakdown does not occur, damage may be caused to the light-emitting end face. As a result, the lifespan of the laser light-emitting element is shortened, and reliability may be impaired. A solution to this problem is disclosed, for example, in Japanese Patent Laid-Open No. 2019-169644 (Patent Document 1). Patent Document 1 discloses a technology that prevents surge voltages from being applied by connecting a Zener diode in parallel to the laser light-emitting element.

[0003] Japanese Patent Application Laid-Open Publication No. 2008-233115 (Patent Document 2) discloses a configuration in which a light intensity control device has a light intensity control means that controls the light intensity of a multi-laser light source based on a voltage detected by a light detection means that detects the light intensity of the multi-laser light source as a voltage, and further includes an overvoltage prevention means that prevents the voltage detected by the light detection means from exceeding a predetermined voltage value.

[0004] Japanese Patent Laid-Open Publication No. 2009-130359 (Patent Document 3) discloses a light-emitting diode element having a function of protecting a light-emitting diode chip from electrostatic discharge, and a method for manufacturing the same. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-169644 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-233115 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-130359 Summary of the Invention [Problem to be solved by the invention]

[0006] Figure 4 shows the waveform of a surge voltage caused by static electricity. In the figure, the X axis represents time and the Y axis represents voltage. As shown in Figure 4, the waveform of a surge voltage caused by static electricity has a first half that rises suddenly on the order of nanoseconds and a second half that transitions on the order of microseconds.

[0007] 5 is a diagram showing the effective range of surge voltage suppression when surge voltage caused by static electricity is suppressed using only a Zener diode as disclosed in Patent Document 1. In the diagram, the X axis represents time and the Y axis represents voltage. The Zener diode used to protect the laser light-emitting element in the configuration disclosed in Patent Document 1 and other documents has a Zener voltage of 2 to 3 V, taking into account the operating voltage of the laser light-emitting element. However, Zener diodes have a slow response, and while they are effective in protecting against overvoltage pulses of μs or more, they are unable to protect against surge voltages caused by static electricity of less than μs.

[0008] Therefore, in Figure 5, the Zener diode's response was too slow to handle the first half of the surge voltage, indicated by the solid line, and it only handled the second half of the surge voltage, indicated by the dotted line.

[0009] On the other hand, TVS diodes (Transient Voltage Suppressors) are also suitable for protecting against surge voltages caused by static electricity. Although TVS diodes have a fast response, they cannot protect against surge voltages caused by static electricity unless the Zener voltage is set to a fairly large voltage (5V or more), and there is also the problem that this is technically difficult, so TVS diodes are not effective in protecting against overvoltage pulses of more than μs and 2 to 3V or more.

[0010] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a semiconductor laser device having a laser light-emitting element that does not cause facet damage due to the flow of a large current even when a surge voltage is applied. [Means for solving the problem]

[0011] A semiconductor laser device according to the present disclosure includes a laser light-emitting element that emits laser light, a first electrostatic protection element that is connected to the laser light-emitting element and has a fast response, and a second electrostatic protection element that is connected in parallel to the first electrostatic protection element and has a slower response than the first electrostatic protection element.

[0012] Preferably, a first electrostatic protection element is disposed near the laser light emitting element.

[0013] The first electrostatic protection element may be a TVS diode, and the second electrostatic protection element may be a Zener diode. [Effects of the Invention]

[0014] According to the present disclosure, the semiconductor laser device includes a first electrostatic protection element connected to a laser light-emitting element and having a fast response, and a second electrostatic protection element connected in parallel to the first electrostatic protection element and having a slower response than the first electrostatic protection element. Therefore, even when a surge voltage is applied, the surge voltage caused by static electricity of less than μs can be suppressed by the first electrostatic protection element with a fast response, and an overvoltage pulse of more than μs and 2 to 3 V can be protected by the second electrostatic protection element with a slower response than the first electrostatic protection element.

[0015] As a result, it is possible to provide a semiconductor laser device having a laser light-emitting element in which facet damage due to a large current flowing even when a surge voltage is applied is not caused.

[0016] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description of the embodiments, which proceeds with reference to the drawings. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a circuit diagram of a semiconductor laser device having a laser light-emitting element according to the present disclosure mounted on a substrate. [Figure 2]1. FIG. 4 is a diagram showing a surge voltage waveform when a surge voltage caused by static electricity is suppressed by a TVS diode and a Zener diode when the semiconductor laser device having the laser light-emitting element shown in FIG. 1 is mounted on a substrate. [Figure 3] FIG. 1 is a diagram showing a CAN package of a laser light emitting element. [Figure 4] FIG. 10 is a diagram showing a surge voltage waveform caused by static electricity. [Figure 5] FIG. 1 is a diagram showing an effective range for suppressing a surge voltage caused by static electricity when the surge voltage is suppressed only by a Zener diode as disclosed in Patent Document 1. DETAILED DESCRIPTION OF THE INVENTION

[0018] [First embodiment] An embodiment of the present disclosure will be described in detail below with reference to the drawings. Fig. 1 is a circuit diagram of a semiconductor laser device having a laser light-emitting element according to the present disclosure mounted on a substrate. Referring to Fig. 1, a semiconductor laser device 10 according to the present disclosure includes a laser light-emitting element 11, a fast-response TVS diode 13, and a slow-response Zener diode 15 connected in parallel.

[0019] Next, the effects of the semiconductor laser device 10 according to the present disclosure will be described. Fig. 2 is a diagram showing a surge voltage waveform when a semiconductor laser device 10 having the laser light-emitting element 11 shown in Fig. 1 is mounted on a substrate and a surge voltage caused by static electricity is suppressed by the TVS diode 13 and the Zener diode 15. In Fig. 2, the X axis represents time and the Y axis represents voltage. Referring to Fig. 2, in the semiconductor laser device 10 according to the present disclosure, the first half of the surge voltage is suppressed by the TVS diode 13 as shown by the solid line, with its peak value being the value indicated by the circle in the figure, so that a steep rise unlike the conventional surge voltage does not occur, and the second half of the surge voltage is suppressed by the Zener diode 15 as shown by the dotted line, so that the surge voltage is similar to the conventional surge voltage shown in Fig. 5.

[0020] That is, in the present disclosure, the fast-response TVS diode 13 is connected in parallel with the slow-response Zener diode 15, so that the first half of the steep rising portion of the surge voltage as shown in FIG. 4 is suppressed by the TVS diode 13, which responds in a short time (ns) of less than μs, and the second half of the overvoltage pulse of μs or more and 2 to 3 V or more can be protected by the Zener diode 15.

[0021] As a result, even if a surge voltage is applied to the laser light emitting element of the semiconductor laser device, the end face is not damaged by a large current.

[0022] [Second embodiment] Next, a specific arrangement of the laser light emitting element 11 and the TVS diode 13 will be described. Fig. 3 is a diagram showing the CAN package of the laser light emitting element 11. Due to its structure, the legs 11a of the CAN package act as a lightning rod and easily dissipate static electricity. Therefore, by placing a fast-responding TVS diode 13 (not shown) closest to the legs 11a of the CAN package of the laser light emitting element 11 shown in Fig. 3, the peak voltage of the surge voltage can be further reduced.

[0023] As a result, in the present disclosure, by arranging the fast-responding TVS diode 13 in a position closer to the point where the static electricity pulse is applied to the laser light-emitting element 11, the laser light-emitting element is less susceptible to the influence of the wiring impedance of the substrate, and the peak voltage of the surge voltage can be made lower.

[0024] As described above, in the present disclosure, the first half of the surge voltage caused by static electricity is protected from the surge voltage caused by static electricity using a first electrostatic protection element such as a fast-response TVS diode that responds in nanoseconds or less, and the second half of the surge voltage is protected from the surge voltage using a second electrostatic protection element such as a Zener diode that responds slower than the first electrostatic protection element.

[0025] As a result, the first half of the surge voltage due to static electricity can be suppressed in the same manner as the second half, and the probability of shortening the lifespan of the laser light emitting element due to damage to the light emitting end face can be further reduced.

[0026] In the above embodiment, a TVS diode and a Zener diode are used as the fast-response first electrostatic protection element and the slow-response second electrostatic protection element, but the present invention is not limited to this. Depending on the speed of response, any one of a serial regulator, an LDO, a shunt regulator, a Schottky diode, and a switching diode may be used as the first and second electrostatic discharge protection elements.

[0027] The present disclosure can be implemented in various other forms without departing from its spirit or main features. Therefore, the above-described embodiments are merely examples and should not be interpreted as being limited. All modifications and variations within the scope of the claims of the present disclosure are within the scope of the present disclosure. [Industrial Applicability]

[0028] According to the present disclosure, a semiconductor laser device using a laser light-emitting element can be provided in which, even when a surge voltage is applied, no end face damage occurs due to the flow of a large current, and therefore the semiconductor laser device is useful. [Explanation of symbols]

[0029] 10. Semiconductor laser device 11 Laser light emitting element 11a CAN package leg 13 TVS diode 15 Zener diode

Claims

1. a laser light emitting element that emits laser light; a first electrostatic protection element connected to the laser light emitting element and having a fast response; a second electrostatic protection element connected in parallel to the first electrostatic protection element and having a slower response than the first electrostatic protection element.

2. 2. The semiconductor laser device according to claim 1, wherein the first electrostatic protection element is disposed near the laser light-emitting element.

3. 2. The semiconductor laser device according to claim 1, wherein the first electrostatic protection element is a TVS diode, and the second electrostatic protection element is a Zener diode.

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