JP2019125712A - Light emitting device, fiber laser device, and control method of light emitting element - Google Patents

Abstract

To provide a light emitting device, a fiber laser device, and a control method of a light emitting element capable of preferably obtaining a desired light output.SOLUTION: The light emitting device includes: a light emitting element; a DC power supply for supplying a current to the light emitting element; a plurality of transistors connected in parallel to each other and controlling a current flowing to the light emitting element in accordance with an applied control voltage; and a control unit that controls the control voltage applied to each of the plurality of transistors. The control unit individually sets the control voltage for each of the plurality of transistors so as to realize light output intensity instructed by the light emitting device.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light emitting device, a fiber laser device, and a control method of a light emitting element.

  BACKGROUND Conventionally, a light emitting device provided with a plurality of semiconductor laser diodes as light emitting elements has been disclosed. These light emitting devices are used as excitation light sources in fiber laser devices (see Patent Documents 1 to 3).

Patent No. 5694711 International Publication No. 2015/111711 JP 2017-54931 A

  The light emitting element outputs light of an intensity corresponding to the flowing current. As a method of controlling the current flowing to the light emitting element, there is known a method of connecting a transistor in series with the light emitting element and adjusting a control voltage applied to the transistor.

  However, in the light emitting element, the current-light output characteristic (IL characteristic) differs from element to element, that is, the IL characteristic varies from element to element. In this case, even if the control voltages applied to the transistors have the same value for different light emitting elements and the currents flowing to the light emitting elements are the same, the obtained light output will be different, and the desired light output can be obtained. There was a problem that it might not exist. In particular, in the case of using a plurality of light emitting elements, variations in I-L characteristics may be accumulated, which may result in a large deviation from a desired light output.

  The present invention has been made in view of the above, and an object of the present invention is to provide a light emitting device, a fiber laser device, and a control method of a light emitting element capable of preferably obtaining a desired light output.

  In order to solve the problems described above and achieve the object, the light emitting device according to one aspect of the present invention is connected in parallel with each other and applied with a light emitting element and a DC power supply for supplying current to the light emitting element. The light emitting device includes: a plurality of transistors that control a current flowing to the light emitting element according to a control voltage; and a control unit that controls a control voltage to be applied to each of the plurality of transistors The control voltage may be set individually for each of the plurality of transistors so as to realize the light output intensity.

  The light emitting device according to one aspect of the present invention is characterized in that the control unit sets the control voltage such that the junction temperature of each of the plurality of transistors does not exceed the allowable upper limit temperature.

  The light emitting device according to one aspect of the present invention includes a storage unit that stores the relationship between the junction temperature for each of the plurality of transistors and the control voltage, and the control unit is configured to execute the storage relationship according to the stored relationship. The control voltage is set.

  The light emitting device according to one aspect of the present invention includes a storage unit that stores the relationship between the output of the light emitting element and the control voltage, and the control unit sets the control voltage according to the stored relationship. It is characterized by

  The light emitting device according to one aspect of the present invention is characterized in that the control unit controls the voltage of the DC power supply to a voltage larger than a voltage capable of driving the light emitting element.

  The light emitting device according to one aspect of the present invention is characterized in that the control unit sets the control voltage so as to avoid a current that maximizes the load of each of the plurality of transistors.

  The light emitting device according to one aspect of the present invention is characterized in that the control unit arbitrarily sets the control voltage.

  A light emitting device according to one aspect of the present invention includes a plurality of the light emitting elements, and the plurality of light emitting elements configure a plurality of light emitting element groups connected in series, and the plurality of transistors include the plurality of light emitting elements. It is characterized in that it is connected in series to the light emitting element group.

  A light emitting device according to an aspect of the present invention includes a plurality of current monitoring units connected in series to each of the plurality of light emitting element groups, and resistance values of the plurality of current monitoring units are different from each other.

  A fiber laser device according to an aspect of the present invention includes the light emitting device according to the aspect of the present invention, and the plurality of light emitting elements are excitation light sources of a light amplification fiber.

  A control method of a light emitting device according to an aspect of the present invention includes a plurality of transistors connected in parallel with each other to control current flowing to the light emitting device according to a control voltage applied so as to realize the instructed light output intensity. Setting the control voltages individually.

  The control method of the light emitting element according to one aspect of the present invention is characterized in that the control voltage is set so that each junction temperature of the plurality of transistors does not exceed an allowable upper limit temperature.

  The control method of a light emitting element according to one aspect of the present invention is characterized in that the control voltage is set in accordance with the relationship between the junction temperature for each of the plurality of transistors and the control voltage.

  The control method of a light emitting element according to one aspect of the present invention is characterized in that the control voltage is set in accordance with a relation between an output of the light emitting element and the control voltage.

  A control method of a light emitting element according to one aspect of the present invention is characterized in that a voltage of a direct current power supply for supplying current to the light emitting element is controlled to a voltage larger than a voltage capable of driving the light emitting element.

  The control method of a light emitting element according to an aspect of the present invention is characterized in that the control voltage is set so as to avoid a current that maximizes the load of each of the plurality of transistors.

  The control method of a light emitting element according to one aspect of the present invention is characterized in that the control unit arbitrarily sets the control voltage.

  In the control method of a light emitting element according to one aspect of the present invention, a plurality of the light emitting elements are provided, and the plurality of light emitting elements constitute a plurality of light emitting element groups connected in series. It is characterized in that the plurality of light emitting element groups are connected in series.

  A control method of a light emitting element according to an aspect of the present invention is characterized in that resistance values of a plurality of current monitoring units connected in series to each of the plurality of light emitting element groups are different.

  According to the present invention, it is possible to preferably obtain a desired light output.

FIG. 1 is a block diagram of a light emitting device according to the first embodiment. FIG. 2 is a circuit diagram of a specific example of the light emitting device according to the first embodiment. FIG. 3 is a diagram showing an example of the relationship between the current flowing through the transistor and the junction temperature. FIG. 4 is a diagram showing an example of the relationship between currents I1 and I2 flowing through two transistors and junction temperature. FIG. 5 is a diagram showing an example of a combination of currents I1 and I2 in the isotherm diagram of FIG. FIG. 6 is a diagram showing an example of time change of current and temperature. FIG. 7 is a diagram showing another example of the relationship between the currents I1 and I2 flowing through the two transistors and the junction temperature. FIG. 8 is an isotherm diagram of FIG. FIG. 9 is a block diagram of a light emitting device according to a second embodiment. FIG. 10 is a schematic view of a fiber laser device according to a third embodiment. FIG. 11 is a block diagram of a control unit in FIG. FIG. 12 is a diagram showing an example of table data.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited by this embodiment. Moreover, in each drawing, the same code | symbol is suitably attached to the element which is the same or respond | corresponds, and duplication description is abbreviate | omitted.

(Embodiment 1)
FIG. 1 is a block diagram of a light emitting device according to the first embodiment. The light emitting device 10 includes a direct current power source 1, light emitting element units 2-1 to 2-N, transistors 3-1 to 3-N, current control units 4-1 to 4-N, and a current monitoring unit 5-1. To 5 -N and the control unit 6. Here, N is an integer of 2 or more.

  The light emitting element units 2-1 to 2-N include at least one light emitting element. The light emitting element is not particularly limited, but in the present embodiment, the light emitting element is a laser diode (LD). The DC power supply 1 is connected to each of the light emitting element units 2-1 to 2-N, and supplies currents I1 to IN to each of the light emitting element units 2-1 to 2-N.

  The transistors 3-1 to 3-N are field effect transistors (FETs) which are voltage control type transistors in the present embodiment. The transistors 3-1 to 3-N are connected in series to the light emitting element units 2-1 to 2-N, and are connected in parallel to each other. Each of the transistors 3-1 to 3-N can adjust the drain-source current according to the control voltage applied to the gate. Each drain-source current corresponds to the currents I1 to IN. Thus, each of the transistors 3-1 to 3-N can control the current flowing to the light emitting element of each of the light emitting element units 2-1 to 2-N according to the control voltage applied.

  Each of the current monitoring units 5-1 to 5-N is connected in series to each of the light emitting element units 2-1 to 2-N and each of the transistors 3-1 to 3-N. The current flowing to the 2-N light emitting element is monitored, and a monitor signal indicating the monitoring result is output to each of the current control units 4-1 to 4 -N as indicated by a broken arrow.

  The control unit 6 outputs the setting signal of the control voltage to be applied to each of the transistors 3-1 to 3-N to each of the current control units 4-1 to 4-N as indicated by a broken arrow. Further, the control unit 6 can control the voltage of the DC power supply 1. In addition, the control unit 6 receives an instruction signal of light output intensity to the light emitting device 10 from the outside. The instruction signal of the light output intensity to the light emitting device 10 is a signal which instructs the light emitting device 10 on the total intensity (total light output intensity) of the laser light output from the light emitting element sections 2-1 to 2-N of the light emitting device 10. is there.

  The control unit 6 includes an operation unit and a storage unit. The arithmetic unit performs various arithmetic processing for control performed by the control unit 6, and is configured of, for example, a CPU (Central Processing Unit). The storage unit stores various programs, data, etc. used by the operation unit to carry out the operation process, for example, a portion constituted by a ROM (Read Only Memory) and a work space when the operation unit carries out the operation process And a portion configured of, for example, a RAM (Random Access Memory), which is used to store the result of the arithmetic processing of the arithmetic unit and the like. The control function of the control unit 6 is realized as software by the functions of the calculation unit and the storage unit. In addition, the control unit 6 may appropriately include a digital-analog converter (DAC) or an analog-digital converter (ADC).

  The current control units 4-1 to 4-N receive monitor signals from the current monitoring units 5-1 to 5-N and setting signals from the control unit 6, and respond to these signals according to these signals. As indicated by dashed arrows, control voltages applied to the respective transistors 3-1 to 3-N are output. That is, the control unit 6 can control the control voltage applied to each of the transistors 3-1 to 3-N according to the setting signal.

  FIG. 2 is a circuit diagram of a specific example of the light emitting device 10. The light emitting device 10A includes a DC power supply 1A, light emitting element units 2A-1 and 2A-2, transistors 3A-1 and 3A-2, current control units 4A-1 and 4A-2, and a current monitoring unit 5A-1. , 5A-2, a control unit 6, and a Zener diode 7.

  The DC power supply 1A is a known DC power supply. In each of the light emitting element portions 2A-1 and 2A-2, LDs are connected in series to form a light emitting element group. The transistors 3A-1 and 3A-2 are n-channel FETs, respectively. The drain is connected to the light emitting element 2A-1 or 2A-2, and the source is connected to the current monitor 5A-1 or 5A-2 It is done. The current control units 4A-1 and 4A-2 are each an operational amplifier, and the output terminal is connected to the gate of the transistor 3A-1 or 3A-2. The current monitoring units 5A-1 and 5A-2 are each formed of a sense resistor and a current branch unit, and the current signal branched at the current branch unit is an inversion of the operational amplifier of the current control unit 4A-1 or 4A-2. It is connected to be input to the input terminal. The control unit 6 is connected to the non-inversion input terminals of the operational amplifiers of the current control units 4A-1 and 4A-2 so as to input setting signals of the respective control voltages. The Zener diode 7 is provided to stabilize the voltage applied to the light emitting element units 2A-1 and 2A-2, the transistors 3A-1 and 3A-2, and the current control units 4A-1 and 4A-2.

  Returning to FIG. 1, the description will be continued. The control unit 6 individually sets control voltages in the respective transistors 3-1 to 3-N so as to realize the total light output intensity instructed by the light emitting device 10. As described above, by setting the control voltages individually to each of the transistors 3-1 to 3-N, the instruction is issued regardless of the variation in the I-L characteristics of the LDs included in the light emitting element sections 2-1 to 2-N. The desired total light output intensity can be realized, and the desired light output can be suitably obtained.

  The control unit 6 controls the current I1 to IN to be supplied to each of the light emitting element units 2-1 to 2-N in order to realize the instructed total light output intensity, and the respective transistors 3 to supply the currents I1 to IN. The data of the combination with the control voltage individually set to 1 to 3 -N is stored, and the control voltage is set based on the data of the combination. Such combination data can be acquired, for example, by preliminary experiments and stored in the storage unit.

(About the heat generation of the transistor)
By the way, in recent years, the current I1 to IN has been increased with the increase in the output of the LD. As the currents I1 to IN increase, the amounts of heat generation of the transistors 3-1 to 3-N also increase.

Further, in the light emitting device 10 of FIG. 1, assuming that the voltage applied by the DC power source 1 is Vpower, Vpower is, for example, (forward voltage Vf (I1) of light emitting element portion 2-1) + drain of transistor 3-1 Source voltage Vds1) + (voltage drop due to current monitor unit 5-1) When the current monitor unit 5-1 is formed of a sense resistor having a resistance value Rs1 as in the current monitor unit 5A-1 of FIG. 2, the following equation (1) holds.
Vds1 = Vpower−Vf (I1) −Rs1 × I1 (1)
Further, assuming that the power consumption of the transistor 3-1 is P1, P1 is expressed by equation (2).
P1 = I1 × Vds1 (2)
Then, the junction temperature Tj1 of the transistor 3-1 is expressed by the equation (3). Tr1 is the on-resistance of the transistor 3-1, and Ths1 is a parameter that represents the contribution of the heat sink to the junction temperature of the transistor 3-1.
Tj1 = P1 × Tr1 + Ths1
= I1 x Vds1 x Tr1 + Ths1
= I1 x (Vpower-Vf (I1)-Rs1 x (I1)) x Tr1
+ Ths1 (3)
Formulas (1) to (3) also hold for the other light emitting element units 2-2 to 2-N, the transistors 3-2 to 3-N, and the current monitoring units 5-2 to 5-N.

Further, assuming that N = 2, the power consumption W in the light emitting element units 2-1 and 2-2 is represented by the formula (4). This W corresponds to the total light output intensity.
W = I1 × Vf (I1) + I2 × Vf (I2) (4)
Note that, assuming that the transistors 3-1 and 3-2 have the same electrical characteristics and let their junction temperatures be Tj, for example, the point (I1, I2) at which W is determined by the steepest descent method (Lacanger's unknown coefficient method) The point which minimizes Tj can be determined by. That is, I1 and I2 which satisfy Formulas (5) to (8) are solutions.
L (I1, I2, λ)
= Tj + λ (W-I1 × Vf (I1) + I2 × Vf (I2)) (5)
δL (I1, I2, λ) / δI1 = 0 (6)
δL (I1, I2, λ) / δI2 = 0 (7)
δL (I1, I2, λ) / δλ = 0 (8)

  Here, since the IV characteristic of the LD included in the light emitting element portion 2-1 is not linear, the voltage Vds1 adjusted by the transistor 3-1 is also not linear with respect to I1. As a result, depending on the I-L characteristics of the LD and the conditions of Vpower, the load of the transistor 3-1 may have a local maximum value with respect to the current. In this case, for example, as shown in FIG. 3, the junction temperature has a maximum value in a graph in which the current (I1) is taken along the abscissa and the junction temperature of the transistor 3-1 is taken along the ordinate. In such a case, when adjusting I1 in the range of 0A to 15A, for example, the maximum value of I1, that is, I1 where the light emitting element portion 2-1 becomes the maximum light output and I1 where the load of the transistor 3-1 becomes the maximum It will shift. Such a phenomenon also occurs in the other transistors 3-2 to 3-N. Further, in FIG. 3, the broken line indicates the allowable upper limit temperature of the junction temperature of the transistor 3-1. When the junction temperature is at the maximum value, the allowable upper limit temperature may be exceeded.

  When the light emitting device 10 is operated by temporally changing the total light output intensity, the currents I1 to IN may be set to intermediate values. For example, when the light emitting device 10 is applied to an excitation light source or the like of a fiber laser, an intermediate total light output intensity may be used to improve the finish of processing on a target workpiece. On the other hand, as shown in FIG. 3, the transistors 3-1 to 3-N may have the largest calorific value in the case of such an intermediate value. Thermal design may be difficult.

  In order to reduce the load on the transistors, it is also conceivable to connect a plurality of transistors in parallel to reduce the load per one, or to enlarge the heat sink provided to the transistors to increase the amount of heat removed. The method is not preferable because it leads to upsizing of the apparatus.

  Therefore, the control unit 6 preferably sets the control voltage so that the junction temperature of each of the transistors 3-1 to 3-N does not exceed the allowable upper limit temperature.

  In order to implement this, the control unit 6 includes a storage unit that stores the relationship between the junction temperature and the control voltage for each of the transistors 3-1 to 3-N, and sets the control voltage according to the stored relationship. It is preferable to do. The relationship between the junction temperature and the control voltage is to avoid the current that maximizes the load of each of the transistors 3-1 to 3-N, and the junction temperature of each of the transistors 3-1 to 3-N is an allowable upper limit. The control voltage does not exceed the temperature. Such control voltage is also a control voltage for achieving the indicated total light output intensity. This makes it possible to prevent the junction temperature of each of the transistors 3-1 to 3-N from exceeding the allowable upper limit temperature while achieving the instructed total light output intensity.

  The control unit 6 controls the voltage of the DC power supply 1 to a voltage higher than the voltage capable of driving each LD of each light emitting element unit 2-1 to 2-N, but the voltage higher than the voltage capable of driving each LD If the voltage is large, it is preferable to control to a lower voltage. Thereby, the load of each of the transistors 3-1 to 3-N can be reduced.

  A setting example of the currents I1 and I2 will be described by taking the case of N = 2 as an example. FIG. 4 is a diagram showing an example of the relationship between the currents I1 and I2 flowing through the transistors 3-1 and 3-2 and the junction temperature Tj. Note that as the junction temperature Tj, the higher one of the transistors 3-1 and 3-2 is shown. The allowable upper limit of the junction temperature of the transistors 3-1 and 3-2 is about 150.degree.

  FIG. 5 is a diagram showing an example of a combination of currents I1 and I2 in the isotherm diagram of FIG. A line L1 is a line showing a combination of the currents I1 and I2 in achieving a predetermined total light output intensity, and the combination of the currents I1 and I2 located on the line L1 has the same total light output intensity To be realized. Although such a line L1 is generally in the shape of a circular arc, it can be approximated by a straight line, so it is shown by a straight line. Further, in FIG. 5, a cross-shaped region (indicated by a thick line) including the point P1 represented by a combination of the currents I1 and I2 is a region where the junction temperature exceeds the allowable upper limit value.

  Conventionally, when the total light output intensity is increased, as indicated by line L2, the currents I1 and I2 are increased with the same value, but in this case, the allowable upper limit temperature is exceeded at the point P1.

  On the other hand, the control unit 6 sets a control voltage such that the junction temperature of each of the transistors 3-1 and 3-2 does not exceed the allowable upper limit temperature while achieving the instructed total light output intensity. For example, in the lower left region of the cross region, when increasing the total light output intensity, currents I1 and I2 are increased from the value of zero to the same value as shown by line L3a.

  Subsequently, when the point indicated by the combination of the currents I1 and I2 approaches the cross region, it moves to the upper left region without taking a point in the cross region like the line L3b, and in this upper left region The currents I1 and I2 are set so that the light output intensity is obtained. This allows the total light output intensity to be increased continuously. Subsequently, when the total light output intensity is increased, it is preferably increased in the upper left region, but only the current I2 is increased by setting the current I1 to a constant small value, for example, as indicated by a line L3c. Thereby, the load of the transistor 3-1 can be reduced.

  Subsequently, when the current I2 approaches, for example, the upper limit value, thereafter, the current I1 is increased while keeping the current I2 constant as indicated by, for example, a line L3d, and the total light output intensity is increased. Then, when the point indicated by the combination of the currents I1 and I2 approaches the cross region, it moves to the upper right region without taking a point in the cross region like the line L3e, and the total light indicated in the upper right region The currents I1 and I2 are set so that the output intensity is obtained. This allows the total light output intensity to be increased continuously. Subsequently, when the total light output intensity is increased, it is increased in the upper right region, but, for example, as shown by line L3f, the currents I1 and I2 are increased with the same value.

  When the currents I1 and I2 are changed so as to move the point indicated by the combination of the currents I1 and I2 above along the lines L3a to L3f, the junction temperature of the transistors 3-1 and 3-2 is the allowable upper limit value. The total light output intensity can be continuously increased without exceeding it.

  Note that the lines L3a to L3f are merely illustrative and realize the indicated total light output intensity, and under the condition that the point indicated by the combination of the currents I1 and I2 does not exist in the cross region, the current I1 And I2 (setting of control voltage) can be set arbitrarily. In particular, the loads of the transistors 3-1 and 3-2 are preferably set to be as small as possible, preferably the smallest, from a comprehensive viewpoint.

  FIG. 6 is a diagram showing an example of the time change of the currents I1 and I2 and the junction temperature. Line L4 shows the case where the light output is increased while increasing the currents I1 and I2 to the same value as in the prior art, but in this case, the FET temperature changes as shown by line L6 and exceeds the allowable temperature.

  On the other hand, the control unit 6 sets the currents I1 and I2 to the same value as the line L5 until the time t2, and thereafter to the individually different values such as the lines L5a and L5b from the time t2 to t4. After t4, it is changed as the same value as line L5. The combination of the currents I1 and I2 at times t1 to t4 is as shown in FIG. Also in time t2 to t4, the total light output intensity is increased as in the case where the current is increased as in the conventional line L4. That is, the total light output intensity is increased as shown by a line L7 in both cases of the current increase such as the conventional line L4 and the current increase such as the lines L5, L5a and L5b. In this case, the FET temperature changes as indicated by a line L8 for the transistor 3-1 and a line L9 for the transistor 3-2, and none of them can exceed the allowable temperature. Since this current change is determined by the control voltage (for example, the output voltage of the operational amplifier), a control voltage which changes with time as shown by lines L5, L5a and L5b in FIG. It is possible to do by doing.

  FIG. 7 is a diagram showing another example of the relationship between the currents I1 and I2 flowing through the transistors 3-1 and 3-2 and the junction temperature Tj. In the example shown in FIG. 7, the resistance values (for example, the resistance value of the sense resistor) of the current monitoring units 5-1 and 5-2 are different values. Specifically, for example, the value of the sense resistor of the current monitor unit 5-1 is 50 mΩ, and the value of the sense resistor of the current monitor unit 5-2 is 500 mΩ. As a result, the voltage drop in the current monitor 5-2 becomes large, so the load of the transistor 3-2 becomes small, the heat generation characteristics of the transistors 3-1, 3-2 become different from each other, and the junction temperature becomes an extreme value. The current values and / or the extrema that are taken are also different from one another.

  FIG. 8 is an isotherm diagram of FIG. 7, but the region where the junction temperature exceeds the allowable upper limit value is from the region of the cross shape shown in FIG. It changes into parallel banded areas (indicated by thick lines). As a result, the choice of the combination of the currents I1 and I2 can be expanded such that the junction temperature of the transistors 3-1 and 3-2 does not exceed the allowable upper limit value. For example, even when selecting a combination of the currents I1 and I2 for achieving the same total light output intensity shown by the line L9 or the line L10 in FIG. 8, a combination which can not be selected in the case of FIG. You can choose the combination you want.

Second Embodiment
FIG. 9 is a block diagram of a light emitting device according to a second embodiment. In this light emitting device 10B, in the configuration of the light emitting device 10 shown in FIG. 1, N = 2, the light emitting element units 2-1 and 2-2 are replaced with the light emitting element unit 2, and the transistors 3-1 and 3-2 are light emitting The element unit 2 is connected in series.

  The light emitting element unit 2 includes a plurality of light emitting elements, and for example, a plurality of LDs are connected in series to constitute a plurality of light emitting element groups.

  Also in the light emitting device 10B, the instructed total light output intensity can be realized regardless of the variation in the I-L characteristics of the LD included in the light emitting element portion 2, and a desired light output can be suitably obtained. it can. In addition, the junction temperature of each of the transistors 3-1 and 3-2 can be prevented from exceeding the allowable upper limit temperature.

  Further, although the example in which the light emitting element unit 2 is configured by a plurality of light emitting elements is shown in the present embodiment, the light emitting element unit may be configured by one light emitting element.

  Although FIG. 9 is described as N = 2, it goes without saying that the same effect can be obtained even if N is an integer of 3 or more.

(Embodiment 3)
FIG. 10 is a schematic view of a fiber laser device according to a third embodiment. The fiber laser 1000 is configured as a fiber laser for laser processing, and includes a plurality of fiber laser devices 100, an optical multiplexing coupler 1001, and a processing head 1002.

  The fiber laser device 100 includes a pumping light source device 10C which is a light emitting device for outputting pumping light, a TFB (Tapered Fiber Bundle) 20 which is an optical multiplexer, a fiber Bragg grating (FBG) 30, and an optical amplification fiber 40. An FBG 50, a TFB 60, an optical branching coupler 70, and a photodetector (PD) 80 are provided.

  The excitation light source device 10C has a configuration similar to that of the light emitting device 10 shown in FIG. 1 except that the light emitting element portions 2-1 to 2-N are replaced with laser modules 2C-1 to 2C-N. Each of these laser modules 2C-1 to 2C-N includes a light emitting element group in which a plurality of LDs are connected in series. The laser modules 2C-1 to 2C-N output excitation light via an optical fiber. The wavelength of the excitation light is, for example, 915 nm.

  The TFB 20 multiplexes and outputs the excitation light output from the laser modules 2C-1 to 2C-N. The FBG 30 transmits excitation light. The optical amplification fiber 40 includes an optical amplification medium (for example, ytterbium ion) which is optically excited at the wavelength of the excitation light, and is optically excited by the excitation light transmitted through the FBG 30 to emit fluorescence. The component of the predetermined wavelength in the fluorescence is laser-oscillated by the action of the optical resonator composed of the FBG 30 and the FBG 50 and the optical amplification fiber 40, and the FBG 50 as a laser beam (for example, a laser beam of 1.1 μm wavelength band) Output from The optical branching coupler 70 branches a part of the output laser light toward the PD 80, and outputs the remaining part to the optical multiplexing coupler 1001 via an optical fiber. The optical multiplexing coupler 1001 multiplexes the laser beams output from the respective fiber laser devices 100 and outputs the multiplexed laser light to the processing head 1002 via the delivery fiber. The processing head 1002 irradiates the combined laser beam onto the processing target. Laser processing is performed by this.

  The PD 80 receives part of the laser light, generates a current signal according to the received light intensity, and outputs the current signal to the excitation light source device 10C. In addition, a setting signal is input from the outside to the excitation light source device 10C.

  The excitation light source device 10C includes a control unit 6C corresponding to the control unit 6 of the light emitting device 10 of FIG. The control unit 6C, as shown in FIG. 11, includes a set light output information receiving unit 6C1, a current light output information receiving unit 6C2, an FET temperature information receiving unit 6C3, an information processing unit 6C4, and a table data storage unit 6C5. , A voltage indication unit 6C6, and a current indication unit 6C7.

  The setting light output information receiving unit 6C1 receives the setting signal of the laser light output of the fiber laser device 100, and acquires the setting light output information included in the setting signal. The current light output information receiver 6C2 receives the current signal from the PD 80, and acquires the current light output information included in the current signal. The FET temperature information receiving unit 6C3 acquires the temperature information of the FET from the thermistor provided in the FET (corresponding to the transistors 3-1 to 3-N in FIG. 1) included in the excitation light source device 10C.

  The table data storage unit 6C5, as shown in FIG. 12, sets the control voltage for N FETs (in FIG. 12 in volts) with respect to the light output of the fiber laser device 100 (in FIG. 12 in watt). The table data including the temperature of the FET (junction temperature) at that time (in FIG. 12, the unit is ° C.) is stored. The information processing unit 6C4 processes the information or data input from the setting light output information receiving unit 6C1, the current light output information receiving unit 6C2, the FET temperature information receiving unit 6C3, and the table data storage unit 6C5, and An instruction signal is output to the current instruction unit 6C7.

  Voltage indication unit 6C6 outputs an indication signal of a voltage to DC power supply 1. The current instructing unit 6C7 outputs the control voltage set for each FET to the current control unit (corresponding to the current control units 4-1 to 4-N in FIG. 1) in order to indicate the current flowing to each FET. .

  Control executed in control unit 6C will be described. First, the controller 6C sets the voltage for the DC power supply 1 based on the setting light output information. For example, when the setting light output is low, the voltage to the DC power supply 1 is also set low.

  Subsequently, the control unit 6C reads the table data from the table data storage unit 6C5, and sets the control voltage for each FET based on the setting light output information. As a result, an appropriate current flows to the LD of the laser modules 2C-1 to 2C-N by each FET, and each of the laser modules 2C-1 to 2C-N outputs excitation light of an appropriate intensity. The light output is the set light output. At this time, the control voltage of each FET is set such that current flows in a combination that does not exceed the allowable upper limit temperature.

  If the current light output obtained by the PD 80 is different from the value of the table data, the value of the FET voltage of the table data may be rewritten by combining the combination so as to become the current light output. Further, when the temperature of the FET obtained by the FET temperature information receiving unit 6C3 is different from the value of the table data (for example, different by 10 ° C. or more), the table data may be rewritten to the obtained temperature of the FET.

  In the above embodiment, the storage unit stores the relationship between the junction temperature and the control voltage for each of the plurality of transistors, and the control unit sets the control voltage according to the stored relationship. However, the present invention is not limited to this, and the storage unit may store the relationship between the output of the light emitting element and the control voltage, and the control unit may set the control voltage according to the stored relationship.

  The present invention is not limited by the above embodiment. The present invention also includes those configured by appropriately combining the above-described components. Further, further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present invention are not limited to the above embodiments, but various modifications are possible.

1 DC power supply 2, 2-1 to 2-N Light emitting element part 3-1 to 3 -N Transistor 4-1 to 4 -N Current control part 5-1 to 5 -N Current monitor part 6 Control part 6 C 1 Setting light output Information receiver 6C2 Current light output information receiver 6C3 FET temperature information receiver 6C4 Information processor 6C5 Table data storage 6C6 Voltage indicator 6C7 Current indicator 7 Zener diode 10 Light emitting device 20, 60 TFB
30, 50 FBG
40 light amplification fiber 70 light branching coupler 100 fiber laser device 1000 fiber laser 1001 light combining coupler 1002 processing head

Claims (19)

A light emitting element,
A DC power supply for supplying a current to the light emitting element;
A plurality of transistors connected in parallel to each other and controlling the current flowing to the light emitting element in accordance with the applied control voltage;
A control unit that controls a control voltage applied to each of the plurality of transistors;
And the control unit individually sets the control voltage to each of the plurality of transistors so as to realize the light output intensity instructed by the light emitting device.   The light emitting device according to claim 1, wherein the control unit sets the control voltage such that junction temperatures of the plurality of transistors do not exceed an allowable upper limit temperature. A storage unit configured to store a relationship between a junction temperature for each of the plurality of transistors and the control voltage;
The light emitting device according to claim 2, wherein the control unit sets the control voltage according to the stored relationship. A storage unit configured to store a relationship between an output of the light emitting element and the control voltage;
The light emitting device according to claim 1, wherein the control unit sets the control voltage according to the stored relationship.   The light emitting device according to claim 1, wherein the control unit controls the voltage of the direct current power supply to a voltage larger than a voltage capable of driving the light emitting element.   The light emitting device according to claim 1, wherein the control unit sets the control voltage so as to avoid a current that maximizes a load of each of the plurality of transistors.   7. The light emitting device according to claim 2, wherein the control unit arbitrarily sets the control voltage. A plurality of light emitting elements are provided, and the plurality of light emitting elements constitute a plurality of light emitting element groups connected in series;
The light emitting device according to any one of claims 1 to 7, wherein the plurality of transistors are connected in series to the plurality of light emitting element groups. A plurality of current monitoring units connected in series to each of the plurality of light emitting element groups;
The light emitting device according to claim 8, wherein resistance values of the plurality of current monitoring units are different from each other.   A fiber laser device comprising the light emitting device according to any one of claims 1 to 9, wherein the light emitting element is a pump light source of a light amplification fiber.   The control voltages are individually set to a plurality of transistors connected in parallel with each other and controlling the current flowing to the light emitting element according to the applied control voltages so as to realize the instructed light output intensity. Control method of the light emitting element.   The method according to claim 11, wherein the control voltage is set such that the junction temperature of each of the plurality of transistors does not exceed the allowable upper limit temperature.   The control method of a light emitting device according to claim 11, wherein the control voltage is set in accordance with a relation between a junction temperature of each of the plurality of transistors and the control voltage.   The control method of a light emitting device according to claim 11, wherein the control voltage is set in accordance with a relationship between an output of the light emitting device and the control voltage.   The control method of a light emitting element according to claim 11, wherein a voltage of a direct current power supply for supplying a current to the light emitting element is controlled to a voltage larger than a voltage capable of driving the light emitting element.   The control method of a light emitting device according to claim 11, wherein the control voltage is set so as to avoid current which maximizes the load of each of the plurality of transistors.   17. The control method of the light emitting element according to claim 12, wherein the control unit arbitrarily sets the control voltage. A plurality of light emitting elements are provided, and the plurality of light emitting elements constitute a plurality of light emitting element groups connected in series;
The control method of a light emitting element according to any one of claims 11 to 17, wherein the plurality of transistors are connected in series to the plurality of light emitting element groups.   The control method of a light emitting device according to claim 18, wherein resistance values of a plurality of current monitoring units connected in series to each of the plurality of light emitting device groups are different.

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