JP2003298182A - Semiconductor laser array device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser array device capable of predicting the time to replace semiconductor laser elements both easily and objectively. <P>SOLUTION: A semiconductor laser array device 80 comprises a semiconductor laser element array 82 in which a plurality of semiconductor laser elements are arranged in an array form, a photodiode array 84 consisting of photodiodes arranged in an array form in accordance with each laser diode (LD) on the rear side of each LD and detecting the light power of the laser light emitted from each LD, respectively, a control circuit 86 for controlling the light output of each LD based on the light output of each LD detected by the PD, a prediction section 88 for predicting the operable time of each LD based on the change with time in light output of each LD detected by the PD, and a display section 90 for displaying the operable time of each LD predicted by the prediction section 88. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-power semiconductor laser array device, and more particularly to an optical amplifier capable of predicting a future operable period of each semiconductor laser element constituting the semiconductor laser array device. Pump light source,
The present invention relates to a high-power semiconductor laser array device that is optimal as a light source for processing equipment, a light source for displays, and the like.

[0002]

2. Description of the Related Art When a semiconductor laser device is used as a light source for a recording / reproducing device such as an optical disk, a laser printer, a laser processing machine, etc., it is necessary to keep the amount of laser light emitted from the semiconductor laser device constant. is there. Therefore, conventionally, an automatic power control (APC) circuit or an automatic current control (Automatic Current Control, ACC) circuit is provided in a driving device for a semiconductor laser device to control the light emission amount of the semiconductor laser device at a constant level. ing.

First, referring to FIG. 5, the above-mentioned equipment
Edge emitting type semiconductor laser, which is widely used as a light source for
An example of the configuration of the element will be described. Figure 5: Edge-emitting type semi-conductor
It is sectional drawing which shows the structure of a body laser element. Edge emission type
Semiconductor laser device (hereinafter simply referred to as a semiconductor laser device
10) is an AlGaAs semiconductor laser device
Then, as shown in FIG. 5, a film is formed on the n-type GaAs substrate 12.
0.5 μm thick n-type GaAs first buffer layer 14, film thickness
0.5 μm n-type Al_0.3Ga_0.7As second buffer layer 1
6, n-type Al with a film thickness of 1.8 μm _0.47Ga_0.53As Crutch
Layer 18, active layer / guide layer 20, p with a thickness of 1.8 μm
Type Al_0.47Ga_0.53The As clad layer 22 and the film thickness of 0.
Double hetero of 5 μm p-type GaAs cap layer 24
(DH) It has a junction laminated structure.

The active layer / guide layer 20 comprises an Al _0.3 Ga _0.7 As guide layer having a film thickness of 60 nm or more and 65 nm or less and an Al _0.1 Ga _0.9 film having a film thickness of 10 nm which is larger than that of the guide layer.
As active layer and A having a film thickness of 60 nm or more and 65 nm or less
It is configured as a three-layer laminated film with a _0.3 Ga _0.7 As guide layer.

P-type GaAs cap layer 24 and p-type Al
Except for the wide stripe-shaped central portion 25 of the upper layer of the _0.47 Ga _0.53 As clad layer 22, B ⁺ (boron) ions are ion-implanted on both sides of the central portion 25 to increase the electric resistance. And the current constriction structure is constituted by this. The stripe width W of the central portion 25 is 100 μm. Also, a metal film such as Ti /
The p-side electrode 28 made of a Pt / Au multilayer metal film is a p-type G
An n-side electrode 30 formed on the aAs cap layer 24 and the current non-injection region 26 and formed of a metal film, for example, a multi-layer metal film of AuGe / Ni / Au is formed on the back surface of the n-type GaAs substrate 12.

To manufacture the semiconductor laser device 10, first, an epitaxial growth step is carried out. That is, the n-type GaAs substrate 12 is grown under reduced pressure, for example, under reduced pressure of about 100 Torr by an epitaxial growth method such as MOCVD.
On top of this, each compound semiconductor layer forming the above-mentioned double hetero (DH) junction laminated structure is formed.

Next, the step of forming a current non-injection region is performed. An ion implantation mask (not shown) having an opening pattern that exposes the current non-implanted region 26 and covers the stripe-shaped central portion 25 is formed on the p-type GaAs cap layer 24.
l film or the like, and then B from above the ion implantation mask.
Ions such as ⁺ are ion-implanted to form the current non-injection region 26 with increased electric resistance. Next, Ti / Pt / Au
After forming the p-side electrode 28 made of the multilayer metal film on the p-type GaAs cap layer 24 and the current non-injection region 26, and polishing the back surface of the n-type GaAs substrate 12 to have a predetermined substrate thickness, An n-side electrode 30 made of a AuGe / Ni / Au multilayer metal film is formed on the back surface of the substrate. Next, the semiconductor laser element 10 can be manufactured by cleaving the laser beam at the emitting surface to form a laser bar, and further cutting the laser bar into chips.

Next, referring to FIG. 6, a schematic structure and operation of an APC circuit provided as a control circuit for controlling the optical output of the semiconductor laser device will be described. FIG. 6 is a circuit diagram showing an example of the APC circuit. In FIG. 6, Vcc (+ 5V) indicates the power supply voltage. As shown in FIG. 6, the APC circuit 40 includes a semiconductor laser device (laser diode, hereinafter LD).
A photodiode (hereinafter referred to as PD) 44, which is disposed on the rear side of the LD 42 or the like and detects the laser light emitted from the rear surface of the LD 42 to obtain the optical output, and the PD 44 according to the optical output of the LD 42. The current output from I-V
The first comparator 4 for converting (current-voltage) and outputting to TP1
6 and. Further, the APC circuit 40 inverts and amplifies the potential (potential of TP2) set by the optical output setting VR 48 with the output potential of the first comparator 46 as a reference, and outputs it to TP3. The drive transistor 52 for injecting current into the LD 42 based on the output potential of the 2 comparator 50.

In the APC circuit 40, a current corresponding to the light output of the LD 42 is output from the PD 44. The output current is I-V (current-voltage) converted by the first comparator 46,
It is output to TP1. The potential (TP2 set by the optical output setting VR 48 with reference to the output potential of the first comparator 46)
The potential) is inverted and amplified by the second comparator 50 and output to TP3. The inverted and amplified potential is applied to the drive transistor 52.
Drive transistor 52 outputs a current to be injected into LD 42. As a result, the LD 42 steadily emits light with the predetermined light output set by the light output setting VR 48.

In the APC circuit 40, the LD
When the optical output of 42 increases, the current of PD44 also increases,
The voltage of TP1 drops. Since the voltage of TP1 is connected to the non-inverting input terminal of the second comparator, the potential of TP3 also drops. As a result, the base current of the drive transistor 52 decreases, and as a result, the current injected into the LD 42 also decreases, and the optical output of the LD 42 decreases. In this way, the LD 42 is controlled so as to output the optical output set by the optical output setting VR 48.

By the way, in the pump light source of the optical amplifier,
The pump light source consisted of only one semiconductor laser element
With, you can get the required amount of light emission as a pump light source.
Absent. Therefore, a large amount of light emitted from the pump light source of the optical amplifier, etc.
For a light source that requires
The sum of the output of the semiconductor laser device group gives
I am trying to get it. Even in such a case, multiple half
It is necessary to control the output sum of the conductor laser element at a constant level.
Become. Therefore, for each of the n semiconductor laser elements,
An APC circuit (i = 1 to n) is provided to enable n semiconductor lasers.
The method of driving the device group, or each semiconductor laser device I ₁
~ I_nOf the current output from the photodiode provided in
APC circuit (collectively AP
There is a method of controlling the total current with a C circuit). In addition, many
Semiconductor laser array in which several semiconductor laser elements are arranged in parallel
When controlling the output of the device, the total current is controlled by the batch APC circuit.
Often control.

When the output of the semiconductor laser array device consisting of _n semiconductor laser elements I ₁ to In is controlled by the APC circuit, if one semiconductor laser element out of the n semiconductor laser elements fails, it remains as it is. If so, the total optical output is reduced by the optical output of one semiconductor laser device. Therefore, the total light output, i.e. to prevent a reduction in output the sum of the plurality of semiconductor laser elements I ₁ ~I _n, by increasing the current injected into the semiconductor laser element other than the semiconductor laser device is faulty, their The light output is increased to keep the total light output constant. The control of the total optical output described above is performed even when the method of individually controlling each semiconductor laser device by providing an APC circuit is applied, or when the collective A
The same is true when a method of providing a PC circuit and collectively controlling is applied.

In the output control of the semiconductor laser array device,
Instead of the APC circuit, ACC (Automatic Current Cont
rol) circuit may be used. Referring to FIG. 7, AC
The schematic configuration and operation of the C circuit will be described. FIG. 7 is a circuit diagram of the ACC circuit. As shown in FIG. 7, the ACC circuit includes a constant current circuit 60 that makes the current injected into the semiconductor laser element constant. The constant current circuit 60 shown in FIG. 7 is basically called a sink type constant current source, and includes a drive transistor 63 and a comparator 64, and a current Iop flowing through the LD 62 is a variable resistor 66. It is defined by the following equation by the reference voltage Vr set by and the resistance R1 of the resistor 68. Therefore, if the potential of Vr is raised,
The current Iop increases. It is assumed that a voltage of 6V is applied between the terminals Iop = (Vr + 6V) / R1.

N semiconductor laser devices I₁~ I_nHave
The total output of the semiconductor laser array device
Even when controlling, one half of the n semiconductor laser devices
When the conductor laser element fails, the total light output,
Chi semiconductor laser device I₁~ I _nThe output sum of
To prevent this, adjust the potential of the reference voltage Vr to adjust the total light output.
I try to keep my strength.

[0015]

However, when controlling the total optical output of the semiconductor laser array device consisting of n semiconductor laser element arrays by the APC circuit or the ACC circuit, there are the following problems. APC circuit or AC
In the control of the C circuit, when the one semiconductor laser element in the n semiconductor laser device has failed, the total light output, i.e. to prevent a reduction in the output sum of the semiconductor laser element I ₁ ~I _n, failed The current injected into the semiconductor laser elements other than the existing semiconductor laser elements is increased to control the total optical output to be constant. That is, the operating current per operating semiconductor laser element is higher than that when one operating semiconductor laser element is not in failure. For this reason, the progress of deterioration of the semiconductor laser device having the increased operating current is accelerated, and the future operable period is shortened compared to the case where the operating current is not increased. It is inherently difficult to predict the future operable period of the semiconductor laser device, but since the deterioration progress of the semiconductor laser device is accelerated, each of the n semiconductor laser devices is operated for several hours thereafter. It is becoming increasingly difficult to predict what is possible. Therefore, when replacing the semiconductor laser element of the semiconductor laser array device, it is often dependent on the intuition and experience of the operator, and it is difficult to rationally manage the semiconductor laser array device.

Also, the work of replacing the individual semiconductor laser elements constituting the semiconductor laser array device requires a considerable amount of time and labor including the preparatory work. Nevertheless, it is difficult to predict the replacement time of the semiconductor laser device and to replace the semiconductor laser device whose replacement time is near in advance. Therefore, it was confirmed that the semiconductor laser device actually failed. Later, the semiconductor laser device is replaced. As a result, since it takes a considerable time to replace the semiconductor laser element and restart the semiconductor laser array device, it is difficult to improve the operation efficiency of the semiconductor laser array device.

Further, in order to avoid a loss due to stoppage of a device using the semiconductor laser array device as a light source or the stop of the device, all the semiconductor laser devices including the semiconductor laser device still operable can be replaced. there were. This is costly and lacks in economy.

In view of the above problems, it is an object of the present invention to provide a semiconductor laser array device which can easily and objectively predict the replacement time of a semiconductor laser element.

[0019]

Means for Solving the Problems In the course of research for solving the above problems, the present inventor has noticed the following. Here, with reference to FIG. 8, what the present inventor has paid attention to will be described by taking a semiconductor laser array device having a large number of semiconductor laser elements as an example. FIG. 8 is a schematic layout diagram showing the configuration of the semiconductor laser array device. In FIG. 8, LD and P
Wiring around D and necessary peripheral parts are not shown. As shown in FIG. 8, the semiconductor laser array device 70 includes a large number of semiconductor laser elements (L
D) I ₁ and the LD array 72 of ~I _n, respectively provided on the rear side of the laser stripe of the semiconductor laser element I ₁ ~I _n, photodiode for detecting the output of each of the LDI ₁ ~I _n (PD) It is assumed that it is composed of a PD array 74 of P _{1 to} P _{n and} the output is controlled by the APC circuit.

With reference to FIG. 9, a change with time in the light intensity of each semiconductor laser element, which is the basis for predicting the life of the semiconductor laser element, will be described. In the LD of the LD array, it is assumed that LDm has a defect as shown in FIGS. 9 (a) and 9 (b). The defect is a so-called crystal defect, which is a defect during crystal growth,
It occurs due to various causes such as threading dislocations propagated from the substrate when a compound semiconductor layer constituting the laser resonator structure is epitaxially grown and scratches introduced in the manufacturing process of the semiconductor laser device. 9A is a plan view showing the location of the defect, FIG. 9B is a sectional view showing the location of the defect, and FIG.
(C) is a graph showing the light intensity of the laser light of each semiconductor laser device. After 1 hour of operation from the start of energization, the optical output of each LD of the LD array is as shown in FIG.
The light intensity of I _m is lower than that of other LD, for example, LDI _{m + 1} .

When 1 hour has passed after the start of energization, the LD
The defect of I _m is small, and the influence on the light emission of LDI _m is small, but the defect grows and becomes larger gradually with energization. Then, when 10 hours have passed after the start of energization, the defect has expanded as shown in FIGS. 10 (a) and 10 (b). As a result, after 10 hours of operation from the start of energization, the LD
Light output of each LD in the array, as shown in FIG. 10 (c), the light intensity of the LDI _m is lower than other LD, for example, the LDI _{m + 1.}

Furthermore, at the time when 24 hours have passed after the start of energization, the defect of LDI _m becomes even larger as shown in FIGS. 11 (a) and 11 (b), and even in the adjacent LDI _{m + 1} . It has metastasized. As a result, the light intensities of LDI _m and I _{m + 1} are lowered as shown in FIG. 11 (c). That is, the light intensities of LDI _m and I _{m + 1} detected by the PD are shown in FIG.
As shown in 2, it changes with time. LD immediately after the start of energization
Since there is no defect in I _{m + 1} , it can be seen that the light intensity of LDI _{m + 1} is almost constant, but the light intensity begins to decrease from the time when the defect propagates.

FIG. 13 shows the LDI._m, I_{m + 1}, I_{m + 2}Light of
The change in strength over time is shown. LDI_{m + 2}Is LDI_{m + 1}
LD adjacent to. LDI_{m + 1}Crystal defects propagate up to
Then the LDI next to it_{m + 2}Light intensity is LDI_m, I
_{m + 1}As the light intensity decreases, it rises to make up for it
It This is a measure of the light intensity of the entire semiconductor laser array device.
Since it is controlled by the APC circuit so that it can be kept constant,
Light intensity of the entire conductor laser array device 70, that is, LD
I₁~ I _m~ I_nLDI so that the output sum of
_{m + 2}By increasing the drive current to. Obey
LDI_{m + 2}When a defect propagates in a stripe of
The higher the current density, the greater the progress of defect growth.
The light intensity decreases. That is, LDI_m, I_{m + 1}, I
_{m + 2}The slope of the graph showing the temporal change of the light intensity of
As shown in graphs (a), (b), and (c) of
DI_m, I_{m + 1}, I_{m + 2}It becomes large in order. And
The LD operation stops and the optical output becomes zero.

Therefore, the relationship as shown in FIG. 13, that is, the increase in the number of defects, has been confirmed in advance by experiments, simulations, etc.
Calculate the rate of change in light intensity due to defect expansion and transfer, or the magnitude of change per unit time, and the operable period after that, and set the reference optical intensity change rate due to deterioration of the LD and the operable period thereafter. To do. Then, by measuring the LDI ₁ ~I _m ~I rate of change of the individually detected and the light intensity of each of the light intensity at the corresponding PDP ₁ to P _m to P _n of the _n semiconductor laser array device in operation, The detected light intensity change rate and the reference light intensity change rate are compared to determine the degree of deterioration of the LD, and L
Predict D replacement time. This makes it possible to objectively and easily predict the LD replacement time.

In order to achieve the above object, based on the above findings, the semiconductor laser array device according to the present invention is a semiconductor laser element array in which a plurality of semiconductor laser elements are arranged in an array, and a semiconductor laser. In a semiconductor laser array device including a photodetector which is provided corresponding to each element and detects an optical output of a laser beam emitted from each semiconductor laser element, each semiconductor laser element detected by the photodetector A control circuit for controlling the optical output of each semiconductor laser element based on the optical output of, and the time-dependent change of the optical output of each semiconductor laser element detected by the photodetector is calculated periodically or in response to a command each time, A prediction unit that predicts a subsequent operable period of each semiconductor laser device based on a change over time, and a subsequent operation of each semiconductor laser device predicted by the prediction unit It is characterized in that a display unit which displays the ability period.

In the semiconductor laser array device according to the present invention, the control circuit controls the optical output of each semiconductor laser element based on the optical output of each semiconductor laser element detected by the photodetector, and also controls each semiconductor laser element. The optical output of the above is output to the prediction unit. The control circuit basically has the same configuration as the above-mentioned conventional APC circuit or ACC circuit, and each semiconductor laser device is provided with an APC circuit or an ACC circuit provided individually for each semiconductor laser device. May be controlled, or may be collectively controlled by the collective APC circuit.

The predicting unit preliminarily conducts experiments, simulations and the like to establish the relationship as shown in FIG. 13, that is, increase in the number of defects, enlargement of defects, change rate of light intensity due to transfer or magnitude of change per unit time, and The subsequent operable period is calculated, and the reference light intensity change rate due to the deterioration of the semiconductor laser device and the subsequent reference operable period are set. Then, the prediction unit calculates the change over time of the optical output of each semiconductor laser element detected by the photodetector periodically or each time in response to a command, and compares the calculated change over time with the reference light intensity change rate. Then, the subsequent operable period of each semiconductor laser device is predicted based on the subsequent reference operable period. The display is
A CRT, a liquid crystal display device, or the like, which displays a subsequent operable period of each semiconductor laser predicted by the prediction unit.

The change over time in the optical output of each semiconductor laser device may be the magnitude of the change over time or the rate of change over time in which the magnitude of the change over time is divided by the elapsed time. And
The operable time period of each semiconductor laser is predicted by comparing the reference time-dependent change or the reference time-dependent change rate previously obtained by experiments, simulations, etc. with the calculated time-dependent change or the time-dependent change rate.

In a preferred embodiment of the present invention, the control circuit adds the signals from the photodetectors that detect the optical output of each semiconductor laser element to obtain the output sum of the semiconductor laser element array, and the addition means. The output sum obtained by the means is compared with the preset output sum, and the addition means is obtained based on the comparison means for outputting a signal corresponding to the comparison result and the signal output from the comparison means. And a current adjusting unit that adjusts the injection current of each semiconductor laser element by giving an arbitrary weight so that the output sum becomes the set output sum.
Subsequent operable period of each semiconductor laser element based on the temporal change of the optical output of each semiconductor laser element detected by the photodetector or the temporal change of the injection current output from the current adjusting means to each semiconductor laser element. Predict.

The control circuit basically has the same configuration as the conventional APC circuit or ACC circuit and performs the same function. The predicting unit is configured to change the optical output of each semiconductor laser element detected by the photodetector of the control circuit with time, or the injection current output from the current adjusting unit to each semiconductor laser element with time. Predict the subsequent operational period of the device.

In a preferred embodiment of the semiconductor laser array device according to the present invention, photodetectors are arranged in an array behind each semiconductor laser element corresponding to each semiconductor laser element forming the semiconductor laser element array. Has been done.
As a result, the semiconductor laser array device can be made compact and compact. Further, the photodetector is not limited as long as it can detect the optical output of the laser light emitted from each semiconductor laser element, and as the photodetector, for example, a photodiode, a linear sensor, and a charge coupled device (Charge Coupled Device, And / or CCD) can be used.

INDUSTRIAL APPLICABILITY The present invention can be applied without restriction to the type of laser stripe of a semiconductor laser device and the composition of the compound semiconductor layer constituting the semiconductor laser device, and particularly as a high output semiconductor laser array device, for example, as a pump light source for crystal excitation It can be optimally applied to the semiconductor laser array device used.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail based on embodiments with reference to the accompanying drawings. Embodiment 1 This embodiment is an example of an embodiment of a semiconductor laser array device according to the present invention. FIG. 1 is a block diagram showing a configuration of a semiconductor laser array device of the present embodiment example, FIG. 2 is a block diagram showing a configuration of a control circuit, and FIG. 3 is a perspective view showing a configuration of the semiconductor laser array device of the present embodiment example. Is.
As shown in FIG. 1, the semiconductor laser array device 80 of the present embodiment example has a semiconductor laser element array 8 in which a plurality of semiconductor laser elements (hereinafter referred to as LDs) are arranged in an array.
2 and a photodiode (hereinafter referred to as PD) which is arranged on the rear side of each LD in an array corresponding to each LD and detects the optical output of the laser light emitted from each LD. An array 84, a control circuit 86 that controls the optical output of each LD based on the optical output of each LD detected by the PD, and each L detected by the PD.
A prediction unit 88 that predicts the operable period of each LD based on the change over time of the optical output of D, and a display unit 90 that displays the operable period of each LD predicted by the prediction unit 88 are provided.

Each LD has the same structure as that of the edge emitting semiconductor laser device 10 described above, and as shown in FIG. 8, they are arranged in parallel in an array to form a semiconductor laser device array 82. There is. Semiconductor laser device array 82
May be a so-called laser bar, or may be one in which laser bars are pelletized into chips and arranged in an array. As shown in FIG. 8, the photodiode array 84 includes a plurality of PDs arranged in parallel on the rear side of the semiconductor laser device array 82 so as to correspond to the LDs. Further, as the photodiode array 84, a commercially available low-priced linear sensor provided with an ND filter for adjusting the light amount may be used. Most linear sensors use a one-dimensional CCD.

The control device 86, as shown in FIG.
The addition means 86a for obtaining the output sum of the semiconductor laser array by adding the signals from the PD, which has detected the optical output of D, and the output sum obtained by the addition means are compared with the preset output sum. , Comparing means 86b for outputting a signal according to the comparison result, and a signal outputted from the comparing means,
Current adjusting means 86c is provided for adjusting the injection current of each LD by giving an arbitrary weight so that the output sum obtained by the adding means becomes the set output sum. The adding means 86a is an adder having a known structure, and the comparing means 86b is the conventional APC circuit 4.
0 corresponds to a circuit including the first comparator 46 and the optical output setting VR 48, and the current adjusting unit 86c corresponds to a circuit including the second comparator 50 and the drive transistor 54. That is, the control device 86 basically has the same configuration as the conventional APC circuit. Further, the control device 86 can be configured with a conventional ACC circuit by adding an adding means.

Structurally, for example, as shown in FIG. 3, the semiconductor laser device array 82 is mounted on a heat sink 92 via a submount 91 having good thermal conductivity in order to quickly release the heat generated by each LD. Has been done. The semiconductor laser array 82 is soldered to the submount 91, and the submount 91 is soldered to the heat sink 92. The submount 91 and the heat sink 92 are
It is formed of a material having a large thermal conductivity such as SiC, CuW, or diamond, and is mounted by soldering on a metal material having a large thermal conductivity such as Cu.

Further, the photodiode array 84 is
The semiconductor laser element array 82 is fixed and mounted on the rear side with an organic adhesive having high thermal conductivity or solder. The heat sink 92 has a microcomputer 93.
A wiring board on which is mounted is arranged. Further, a copper electrode pad 95 on the (−) side is provided on the heat sink 92 via an insulating plate 94, and each LD of the semiconductor laser array 82 is connected via a connection wiring 96 made of Au wire or Au foil.
And supplies a current to each LD. The (−) Cu electrode 95 is placed on the heat sink 92 by sandwiching an insulating plate 94 such as a glass plate or an epoxy resin plate between the heat sink 92 and the electrode pad 95 in order to insulate the (+) Cu electrode on the heat sink 92 side. It is fixed.

The predicting section 88 includes an arithmetic circuit for predicting the operable period of each LD based on the change over time of the injection current output from the current adjusting means 86c of the control circuit 88. The predicting unit 88 preliminarily conducts a relationship as shown in FIG. 13 by experiments, simulations, etc., that is, an increase in the number of defects, an increase in defects, a change rate of light intensity due to transfer or a magnitude of change per unit time, and the following. The operable period is calculated, and the reference light intensity change rate due to the deterioration of the LD and the subsequent reference operable period are set. Then, the prediction unit 88 uses the PD
The change over time of the light output of each LD detected by the calculation circuit is calculated periodically or each time in response to a command, and the calculated change over time and the reference light intensity change rate are compared, and the subsequent reference operable period Based on, the operable period after each LD is predicted.

Each L calculated by the calculation of the prediction unit 88
The life of D is displayed on the display unit 90. In the display, the display unit 90 may display the operable period thereafter on the liquid crystal display panel, or may provide a red LED as an alarm lamp and light it to inform that the replacement time is near. Alternatively, the red LED may emit light when the estimated life of the LD reaches a convenient remaining life time, for example, 24 hours or 8 hours when the user replaces the unit.

In this embodiment, the LD is AlGaA.
Although an s-based semiconductor laser device is used, the invention is not limited to this. For example, as a semiconductor laser device, AlGaI
You may use an nP type | system | group semiconductor laser element and an AlGaInN type | system | group semiconductor laser element.

Embodiment 2 This embodiment is another example of the embodiment of the semiconductor laser array device according to the present invention, and FIG. 4 is a semiconductor laser device constituting the semiconductor laser array device of this embodiment. 3 is a cross-sectional view showing the configuration of FIG. The semiconductor laser array device of the present embodiment uses a buried ridge type AlGaInP-based semiconductor laser device (hereinafter, simply referred to as AlGaInP-based semiconductor laser device) as a light emitting source. As shown in FIG. 4, the AlGaInP based semiconductor laser device 100 has an n-type G
An n-type Al (Ga) InP cladding layer 104, an undoped AlGaInP optical waveguide layer 106, and an active layer 108 having an MQW structure, which are sequentially epitaxially grown on the aAs off substrate 102 by a metal organic chemical vapor deposition (MOCVD) method. , Undoped AlGaInP optical waveguide layer 11
0, p-type Al (Ga) InP clad layer 112, p-type G
aInP etching stop layer 114, p-type AlGaInP
The clad layer 116, the p-type GaInP intermediate layer 118, and the p-type GaAs cap layer 120 have a laminated structure.

The n-type GaAs off-substrate 102 is, for example, an n-type GaAs substrate having a main surface off from the {100} plane in the <110> direction by a predetermined angle, for example, about 8 ° to 16 °. The active layer 106 is made of undoped GaI.
The nP layer is used as a quantum well layer (GaInP quantum well layer), and the undoped AlGaInP layer is used as a barrier layer (AlGaInP).
Barrier layer).

In the laminated structure, the p-type AlGaInP clad layer 11 on the p-type GaInP etching stop layer 114 is formed.
6, the p-type GaInP intermediate layer 118, and the p-type GaAs cap layer 120 are formed as stripe-shaped ridges. p-type GaInP etching stop layer 114
Is a p-type AlGaInP clad layer 116, a p-type GaI
nP intermediate layer 118 and p-type GaAs cap layer 120
To function as an etching stop layer when the ridge is formed by etching. Both sides of the ridge are n-type AlGaAs
The current confinement structure is formed by embedding the buried layer 122.

As an example of the thickness of each semiconductor layer constituting the above laser structure, the thickness of the n-type Al (Ga) InP cladding layer 104 is 1 μm, and the AlGaInP optical waveguide layer 1 is
The thicknesses of 06 and 110 are 50 nm, respectively, and the active layer 108 is
Of the GaInP quantum well layer forming the
The GaInP barrier layer has a thickness of 5 nm and p-type Al (Ga) I
The thickness of the nP clad layer 112 is 0.15 to 0.5 μm,
The thickness of the p-type GaInP etching stop layer 114 is 10 to 10.
The thickness of the p-type AlGaInP cladding layer 116 is 500 μm, and the thickness of the p-type GaAs cap layer 120 is 0.3 μm.

For example, Ti / P is formed on the p-type GaAs cap layer 120 and the n-type AlGaAs current confinement layer 122.
A p-side electrode 124 such as a t / Au electrode is provided, while, for example, AuG is provided on the back surface of the n-type GaAs substrate 102.
An n-side electrode 126 such as an e / Ni electrode is provided. The semiconductor laser array device of the present embodiment is different from the first embodiment except that the configuration of the semiconductor laser element is different.
The semiconductor laser array device 80 has the same configuration.

Needless to say, the semiconductor laser array device according to the present invention is not limited to the light source of the optical amplifier or the light source of the laser processing device. Although the present invention has been described with reference to the embodiments, the present invention can be modified in various ways according to the gist of the present invention, and these modifications are not excluded from the present invention. For example, as a so-called screening method, by applying the technical idea of the present invention to the manufacturing process and the inspection process of the semiconductor laser array device, the semiconductor laser array device being manufactured or inspected is energized to remove the defective semiconductor laser element. When used, it is useful for accurately estimating the life of the semiconductor laser device, improving the accuracy of screening, and improving the quality of products.

[0047]

According to the present invention, the change over time in the optical output of each semiconductor laser element detected by the photodetector is calculated periodically or each time in response to a command, and each semiconductor laser element is calculated based on the change over time. By providing the semiconductor laser array device with a predicting unit for predicting the subsequent operable period, it is possible to predict the subsequent operable period or replacement time of each semiconductor laser element constituting the semiconductor laser array device. As a result, it is possible to objectively perform maintenance and inspection of the semiconductor laser array device and easily predict the replacement time of the semiconductor laser element without relying on the experience and intuition of the operator as in the conventional case.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a semiconductor laser array device according to a first embodiment.

FIG. 2 is a block diagram showing a configuration of a control circuit.

FIG. 3 is a perspective view showing a configuration of a semiconductor laser array device according to a first embodiment.

FIG. 4 is a cross-sectional view showing the configuration of a semiconductor laser element that constitutes the semiconductor laser array device of the second embodiment.

FIG. 5 is a cross-sectional view showing a configuration of an edge emitting semiconductor laser device.

FIG. 6 is a circuit diagram showing an example of an APC circuit.

FIG. 7 is a circuit diagram showing an example of an ACC circuit.

FIG. 8 is a schematic diagram showing a configuration of a semiconductor laser array device.

9 (a) is a plan view showing the location of a defect, FIG.
9B is a cross-sectional view showing the location of a defect, and FIG. 9C is a graph showing the light intensity of the laser light of each semiconductor laser device.

10A is a plan view showing the location of a defect at the time when one hour has elapsed after the start of operation, FIG. 10B is a sectional view showing the location of the defect, and FIG. It is a graph which shows the light intensity of the laser beam of a semiconductor laser element.

FIG. 11 (a) is a plan view showing the location of a defect at a time point 1 hour after the start of operation, FIG. 11 (b) is a cross-sectional view showing the location of the defect, and FIG. It is a graph which shows the light intensity of the laser beam of a semiconductor laser element.

FIG. 12 is a graph showing the relationship between the light intensities of the semiconductor laser devices I _m and I _{m + 1} and the elapsed time after the start of operation.

FIG. 13 is a graph showing the relationship between the light intensity of the semiconductor laser devices I _m , I _{m + 1} , and I _{m + 2} and the elapsed time after the start of operation.

[Explanation of symbols]

10 ... AlGaAs semiconductor laser device, 12 ... n
-Type GaAs substrate, 14 ... N-type GaAs first buffer layer, 16 ... N-type Al _0.3 Ga _0.7 As second buffer layer,
18 ... n-type Al _0.47 Ga _0.53 As clad layer, 20 ...
... Active layer / guide layer, 22 ... P-type Al _0.47 Ga _0.53 A
s clad layer, 24 ... p-type GaAs cap layer, 25
... central part, 26 ... current non-injection region, 28 ... p-side electrode, 30 ... n-side electrode, 40 ... APC circuit, 42 ...
LD, 44 ... PD, 46 ... First comparator, 48 ... Optical output setting VR, 50 ... Second comparator, 52 ... Drive transistor, 60 ... ACC circuit, 62 ... LD,
63 ... Drive transistor, 64 ... Comparator, 66
... variable resistor, 68 ... resistor, 70 ... semiconductor laser array device, 72 ... LD array, 74 ... PD array, 80 ... semiconductor laser array device of the first embodiment,
82 ... Semiconductor laser element array, 84 ... Photodiode array, 86 ... Control circuit, 86a ... Addition means, 86b ... Comparison means, 86c ... Current adjustment means, 8
8 ... Prediction part, 90 ... Display part, 91 ... Submount, 92 ... Heat sink, 93 ... Microcomputer mounted substrate, 94 ... Insulation plate, 95 ... Copper electrode pad, 96 ... Connection Wiring, 100 ... Embodiment 2
AlGaInP-based semiconductor laser device of the semiconductor laser array device, 102 ... N-type GaAs off-substrate, 104 ...
... n-type Al (Ga) InP clad layer, 106 ... undoped AlGaInP optical waveguide layer, 108 ... active layer of MQW structure, 110 ... undoped AlGaInP optical waveguide layer, 112 ... p-type Al (Ga) InP Cladding layer, 114 ... p-type GaInP etching stop layer, 11
6 ... p-type AlGaInP clad layer, 118 ... p-type GaInP intermediate layer, 120 ... p-type GaAs cap layer, 122 ... n-type AlGaAs buried layer, 124 ...
... p-side electrode, 126 ... n-side electrode.

Claims (5)

[Claims] 1. A semiconductor laser device array in which a plurality of semiconductor laser devices are arranged in an array, and an optical output of laser light emitted from each semiconductor laser device provided corresponding to each semiconductor laser device. In a semiconductor laser array device including a photodetector for detecting the light, a control circuit for controlling the light output of each semiconductor laser element based on the light output of each semiconductor laser element detected by the photodetector, and the photodetector Calculate the change over time of the optical output of each semiconductor laser element detected by the periodical or each time according to the command,
It is characterized by further comprising: a prediction unit that predicts a subsequent operable period of each semiconductor laser device based on a change over time, and a display unit that displays a subsequent operable period of each semiconductor laser device predicted by the prediction unit. Semiconductor laser array device. 2. The control circuit adds the signals from the photodetectors that have detected the optical output of each semiconductor laser element to obtain the output sum of the semiconductor laser element array, and the output sum obtained by the addition means. , Comparing the preset output sum with the comparing means for outputting a signal corresponding to the comparison result, and the output sum obtained by the adding means based on the signal output from the comparing means becomes the set output sum. And a current adjusting unit that adjusts the injection current of each semiconductor laser element by giving an arbitrary weight so that the predicting unit changes the optical output of each semiconductor laser element detected by the photodetector with time, or the current. 2. The semiconductor laser array device according to claim 1, wherein a subsequent operable period of each semiconductor laser element is predicted based on a change with time of an injection current output from the adjusting means to each semiconductor laser element. 3. The photodetector is arranged in an array behind each semiconductor laser element corresponding to each semiconductor laser element that constitutes the semiconductor laser element array. The semiconductor laser array device described in 1. 4. The photodetector includes a photodiode, a linear sensor, and a charge coupled device (Charge Coupled Device).
4. The semiconductor laser array device according to claim 1, wherein the semiconductor laser array device is at least one of a CCD). 5. The semiconductor laser array device according to claim 1, which is used as a pump light source for crystal excitation.