JP4034805B2 - Method and apparatus for detecting input / output characteristics of semiconductor laser element - Google Patents

Description

  The present invention relates to a method and apparatus for detecting input / output characteristics of a pulse-driven semiconductor laser device.

  In recent years, as one of typical photoelectronic devices, a semiconductor laser element has been used in many fields. For example, in the field of an optical disk drive, a semiconductor laser element that is pulse-driven as a light source for writing is used. . In this field, as the demand for higher writing speeds is increasing, semiconductor laser elements have been increasing in output and speed year by year, so that stable laser oscillation is possible even with high output and short pulse drive. It is necessary to provide a simple semiconductor laser element.

  By the way, some of the manufactured semiconductor laser elements have a disorder of linearity on a graph showing optical output characteristics (input / output characteristics) with respect to drive current in a high current region. Such a phenomenon is called a kink phenomenon, and the oscillation of the transverse mode becomes unstable. Therefore, such a semiconductor laser element cannot be used as a light source for writing.

  Therefore, in the manufacture of semiconductor laser elements, screening is performed by measuring input / output characteristics of all manufactured semiconductor laser elements, and semiconductor lasers that generate kinks as described above are removed. (For example, refer to Patent Document 1).

  When detecting input / output characteristics of such semiconductor laser elements, kinks may occur during short pulse drive even if kinks do not occur during continuous drive. In the light output characteristic measurement, it is necessary to perform measurement under a high-speed and short-pulse driving condition that matches the actual use condition.

However, under the high-speed pulse driving condition, there is a problem that the response performance of the light receiving element is insufficient and an accurate peak value of pulsed light cannot be measured. On the other hand, responsiveness can be improved by reducing the light receiving area of the light receiving element, but in such a case, the total luminous flux of the laser light output from the element to be inspected cannot be received and the coupling efficiency is lowered. There is a problem that it is difficult to measure an accurate peak value of light.
JP 2000-241294 A

  The present invention has been made in view of the above problems, and provides an input / output characteristic detection method and apparatus for a semiconductor laser element capable of accurately measuring the input / output characteristics of the semiconductor laser element in high-speed and short-pulse driving. The purpose is to do.

The invention according to claim 1 is: (1) driving a semiconductor laser element by inputting a first current pulse train signal having a first pulse width and increasing a peak value stepwise with a constant period; The first pulse light emitted from the semiconductor laser element is received by a first light receiving element having a light receiving surface capable of receiving all of the light flux, and photoelectrically converted to obtain a first detection pulse signal, (3) the first A first input / output characteristic indicating a change in a peak value of the first detection pulse signal with respect to a peak value of the first current pulse train signal at a first sample time set at a predetermined time from the rising point of one pulse of the one detection pulse signal. (4) a first step of calculating a first input / output differential characteristic that is a differential characteristic of the first input / output characteristic; and (1) receiving the first pulsed light smaller than the first light receiving element. Second light receiving element having a surface (2) The first current pulse train signal at the second sample time set at a predetermined time from the rising edge of one pulse of the second detection pulse signal. Detecting a second input / output characteristic indicating a change in the peak value of the second detection pulse signal with respect to a peak value of the second detection pulse; and (3) calculating a second input / output differential characteristic that is a differential characteristic of the second input / output characteristic. And a third step of dividing the second input / output differential characteristic by the first input / output differential characteristic to calculate the coupling efficiency between the semiconductor laser element and the second light receiving element, and (1) the first A second current pulse train signal having a second pulse width shorter than the pulse width and whose peak value increases stepwise with a constant period is input to drive the semiconductor laser element, and (2) emitted from the semiconductor laser element Second pulsed light The light is received by the second light receiving element, photoelectrically converted to obtain a third detection pulse signal, and (3) the third sampling time set at a predetermined time from the rising edge of one pulse of the third detection pulse signal. A fourth step of detecting a third input / output characteristic indicating a change in the peak value of the third detection pulse signal with respect to a peak value of the second current pulse train signal; and dividing each value of the third input / output characteristic by the coupling efficiency. And a fifth step of setting the calibrated third input / output characteristic as the input / output characteristic of the semiconductor laser element, and detecting the input / output characteristic of the semiconductor laser element.

According to a second aspect of the present invention, in the second step, the fourth sample time is set at a predetermined time different from the second sample time from the rising edge of one pulse of the second detection pulse signal, and the fourth sample time A fourth input / output characteristic indicating a change in a peak value of the second detection pulse signal with respect to a peak value of the first current pulse train signal and a fourth input / output differential characteristic which is a differential characteristic thereof are detected; (1) A current section in which the second input / output characteristic and the fourth input / output characteristic coincide with each other and has linearity is set as a calculation section, and (2) the first input / output differentiation in the calculation section An average value of the characteristic, and an average value of the second input / output differential characteristic and the fourth input / output differential characteristic, respectively; (3) the second input / output differential characteristic and the fourth input / output differential characteristic; The average value is the first By dividing the average value of the output differential characteristic, an input-output characteristic detecting method for a semiconductor laser device according to claim 1, characterized in that to calculate the coupling efficiency.
According to a third aspect of the present invention, in the input / output characteristic detection method for a semiconductor laser device according to the first or second aspect, the second sample time is the time from the rising edge of one pulse, and the third sample time. The time is set equal to or shorter than the third sample time.

According to a fourth aspect of the present invention, in the semiconductor laser device input / output characteristic detection method according to any one of the first to third aspects, the first sample time is in the vicinity of the first detection pulse signal before falling. The time is set at the time when the pulse waveform becomes stable.

The invention according to claim 5 is the semiconductor laser device input / output characteristic detection method according to any one of claims 2 to 4 , wherein the fourth sample time is in the vicinity of the second detection pulse signal before falling. The time is set at the time when the pulse waveform becomes stable.

According to a sixth aspect of the present invention, there is provided an input / output characteristic detection method for a semiconductor laser device, comprising: (1) a first pulse width having a peak value that increases stepwise with a constant period; (1) The first pulse light emitted from the semiconductor laser element is received by the first light receiving element having a light receiving surface capable of receiving all the luminous fluxes. The first detection pulse signal is obtained by photoelectric conversion, and (3) the peak value of the first current pulse train signal at the first sample time set at a predetermined time from the rising point of one pulse of the first detection pulse signal. Detecting a first input / output characteristic indicating a change in peak value of the first detection pulse signal with respect to the first input / output characteristic, and (4) calculating a first input / output differential characteristic that is a differential characteristic of the first input / output characteristic And (1) said The first pulse light is received by a second light receiving element having a light receiving surface smaller than the first light receiving element, photoelectrically converted to obtain a second detection pulse signal, and (2) one pulse of the second detection pulse signal (2) detecting a second input / output characteristic indicating a change in a peak value of the second detection pulse signal with respect to a peak value of the first current pulse train signal at a second sample time set at a predetermined time from the rising point of (3) A second operation unit for calculating a second input / output differential characteristic which is a differential characteristic of the second input / output characteristic; and dividing the second input / output differential characteristic by the first input / output differential characteristic; A third arithmetic unit for calculating a coupling efficiency with the second light receiving element; and (1) a second current pulse train having a second pulse width shorter than the first pulse width and increasing the peak value stepwise with a constant period. Input a signal and (2) the second pulse light emitted from the semiconductor laser element is received by the second light receiving element and photoelectrically converted to obtain a third detection pulse signal; A third input / output characteristic indicating a change in the peak value of the third detection pulse signal with respect to the peak value of the second current pulse train signal at a third sample time set at a predetermined time from the rising edge of one pulse of the three detection pulse signals. And a fourth arithmetic unit for detecting the third input / output characteristic by dividing each value of the third input / output characteristic by the coupling efficiency, and using the calibrated third input / output characteristic as the input / output characteristic of the semiconductor laser device. an input-output characteristic detecting apparatus for a semiconductor laser device, characterized by chromatic and calculating unit.

  According to the present invention, the input / output characteristics of a semiconductor laser device in short pulse driving can be solved by solving the problem of response speed of a light receiving element having a large light receiving area and the problem of low coupling efficiency having a light receiving element having a small light receiving area. Can be measured accurately.

  Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block circuit diagram of a semiconductor laser device inspection apparatus 10 according to the present embodiment, FIG. 2 is a graph showing various electrical signals in a current pulse train signal generation circuit 20, and FIGS. FIG. 5 and FIG. 6 are graphs showing light output characteristics measured by the apparatus 10.

  The semiconductor laser device inspection apparatus 10 according to the present embodiment has a short pulse width of about 3 to 20 ns in which the crest value increases stepwise with a constant period in the semiconductor laser device 1 to be inspected, and the ON duty ratio is about 50%. In the short pulse driving state in which the current pulse train signal is input, the peak value of the driving current of the semiconductor laser element 1 and the peak value of the detection pulse signal obtained by converting the emitted pulsed light by the light receiving element are detected. An input / output characteristic detection device that detects a change in the peak value of pulsed light with respect to a change in the peak value of the drive current, and generates a current pulse train signal input to the semiconductor laser device 1 as shown in FIG. A driving circuit 20 that detects the driving current extracted from the semiconductor laser element 1 that has been operated in response to the current pulse train signal, and a current pulse train The light detection circuits 50 and 70 for detecting the pulsed light oscillated from the semiconductor laser element 1 in response to the signal, and the respective circuits 20, 30, 50 and 70 are controlled in accordance with a predetermined operation program and the detection circuits 30 , 50, 70, and a main processor 12 that receives input of detection results and calculates input / output characteristics in pulse driving.

  The drive circuit 20 includes a staircase waveform voltage generation circuit 22 and a pulse current generation circuit 24. The staircase waveform voltage generation circuit 22 that has received an input of a voltage generation command from the main processor 12 is as shown in FIG. In addition, a reference voltage signal Vref whose peak value increases stepwise from 0 V to a predetermined maximum value (eg, 10 V) with a constant period τc (eg, τc = 1 ms) is generated and input to the pulse current generation circuit 24. .

  In the pulse current generation circuit 24 that receives the input of the reference voltage signal Vref, the voltage-current conversion circuit 26 converts the reference voltage signal Vref into a current signal, and the converted current signal is configured using a high-speed switching transistor or the like. By performing ON / OFF control of the switch means 28, a current pulse train signal that has an arbitrary pulse width Pw and an ON duty ratio and whose peak value increases to a predetermined maximum value as shown in FIG. To be molded.

  The switch means 28 is controlled by an ON / OFF switching operation timing pulse sent from a pulse generator (not shown) that operates in response to a pulse width setting command from the main processor 12. A current signal having a width Pw and an ON duty ratio is output.

  In the above drive circuit 20, a comparison circuit is interposed between the staircase waveform voltage generation circuit 22 and the pulse current generation circuit 24, and the reference voltage signal Vref input from the staircase waveform voltage generation circuit 22 and the current detection circuit 30. Based on the deviation from the peak value of the driving current of the semiconductor laser element 1 that is input, the reference voltage signal Vref output to the pulse current generating circuit 24 is output so that the peak value of the driving current of the semiconductor laser element 1 becomes a predetermined value. Feedback control may be performed.

  The current pulse train signal generated in the current pulse train signal generation circuit 20 is input to the semiconductor laser element 1 to be inspected, so that the semiconductor laser element 1 has the peak value and the pulse width Pw of the current pulse train signal that is the drive current. Pulse light having a corresponding light intensity and pulse width is emitted.

  The pulsed light emitted from the semiconductor laser element 1 is converted into a detection pulse signal by the light receiving element photodiodes 60 and 62 and then input to the photodetection circuits 50 and 70 to detect the peak value of the pulsed light. It is like that.

  More specifically, a first light receiving element 60 and a second light receiving element 62 made of, for example, a Si photodiode are disposed in the vicinity of the semiconductor laser element 1, and are selected from the first light receiving element 60 and the second light receiving element 62. One light receiving element receives pulsed light emitted from the semiconductor laser element 1.

  The first light receiving element 60 has a light receiving area capable of receiving the entire luminous flux of the pulsed light emitted from the semiconductor laser element 1, for example, a light receiving area of about 10 mm × 10 mm, and detects the received pulsed light. A photoelectric conversion into a pulse signal is performed, and this is input to the first photodetection circuit 50. The second light receiving element 62 has a light receiving area smaller than that of the first light receiving element 60, for example, a light receiving area of about φ0.8 mm, and is output from the semiconductor laser element 1 during short pulse driving with a pulse width of about 3 ns to 20 ns. It has a sufficient response speed with respect to the pulsed light, photoelectrically converts the received pulsed light into a detection pulse signal, and inputs this to the second light detection circuit 70.

  The optical measurement circuit 50 to which the detection pulse signal from the first light receiving element 60 is input includes an amplifier 52, an A / D converter 54, and a latch circuit 56. The detection pulse signal is supplied to the amplifier 52 and the A / D converter 54. Is amplified and digitally converted, and this is input to a latch circuit 56 comprising a plurality of stages (in this embodiment, two stages) of latch ICs, whereby the peak value of the detection pulse signal input to each latch IC is measured. It is supposed to be.

  More specifically, the detection pulse signal for one pulse input to the A / D converter 54 is converted into a digital signal each time at the rising edge of the conversion clock of the A / D converter 54 as shown in FIG. And input to each of the two-stage latch ICs of the latch circuit 56 arranged at the subsequent stage of the A / D converter 54.

  In addition, the two-stage latch IC constituting the latch circuit 56 has an arbitrary 2 from the rise time T0 of the pulse in one pulse of the first detection pulse signal from the timing circuit 40 that has received the latch command from the main processor 12. One latch timing signal set at each time Ts is input. As a result, the peak value of the drive current at any two times from the pulse rising time T0 can be measured in one pulse. That is, the time Ts set during one pulse is a sample time for detecting the peak value of the drive current during one pulse. The measured peak values of the drive current at the two sample times are output from the current detection circuit 30 and transferred to the main processor 12.

  Note that, in the A / D converter 54, a conversion time lag of a period corresponding to several clocks (for example, 6 to 8 clocks) occurs between the input of the drive current and the output of the digital conversion result. In such a case, the latch timing signal in FIG. 3 may be set to a time delayed by a period corresponding to the conversion time lag.

  The optical measurement circuit 70 to which the detection pulse signal from the second light receiving element 62 is input has the same configuration and operation as the first photodetection circuit 50, and includes an amplifier 72, A / D conversion. And a latch timing signal set at any two sample times from the pulse rising time T0 in one pulse of the detection pulse signal from the second light receiving element 62. By being input, the peak value of the detection pulse signal at any two times from the pulse rising time T0 is measured and transferred to the main processor 12 as the peak value of the pulsed light.

  The peak value of the drive current flowing through the semiconductor laser element 1 is detected by the current detection circuit 30 having the same configuration and operation as the above-described photodetection circuits 50 and 70.

  The current detection circuit 30 includes an amplifier 32, an A / D converter 34, and a latch circuit 36, and amplifies and digitally converts the drive current via the amplifier 32 and the A / D converter 34 to latch in two stages. It outputs to the latch circuit 36 which consists of IC. The latch circuit 36 receives from the timing circuit 40 a latch timing signal set at any two sample times from the pulse rise time T0 in one pulse of the drive current, whereby the pulse rise time T0. The peak value of the drive current at any two times is measured and transferred to the main processor 12.

  Then, for all current pulses having different peak values of the current pulse train signal output from the current pulse train signal generation circuit 20, a predetermined sample is obtained by one of the light receiving elements selected from the first light receiving element 60 and the second light receiving element 62. While measuring the peak value of the pulsed light at the time, the drive current of the semiconductor laser device 1 at the same time as the sample time is measured.

  Thus, any one of the pulses in the pulse driving state in which the current pulse train signal having an arbitrary pulse width Pw and ON duty ratio is input by one of the first light receiving elements 60 and the second light receiving element 62 is selected. The input / output characteristics, which are the characteristics of the optical output P with respect to the drive current I of the semiconductor laser device 1 at the sample times set at the two times, and the differential characteristics (ΔP / ΔI) are respectively measured.

  In such an inspection apparatus 10, input / output characteristics at the time of short pulse driving in which the pulse width corresponding to the actual use condition of the semiconductor laser element 1 is about 3 ns to 20 ns and the ON duty ratio is about 50% are detected as follows.

That is, a current pulse train signal having a pulse width longer than the pulse width at the time of the short pulse driving described above, for example, a pulse width of about 20 ns to 100 ns and an ON duty ratio of about 1 to 10% that can ignore heat generation is input. In the pulse driving state in which the first pulsed light is emitted from the semiconductor laser element 1, as shown in FIG. 4A, the first sample time T1 set at a predetermined time from the pulse rising time T0 during one pulse. By measuring the input / output characteristics and the differential characteristics thereof with the first light receiving element 60, the input / output characteristics and their differential characteristics respectively indicated by reference numerals C1 and D1 in FIGS. 5A and 5B are obtained. At this time, the rising portion of the detection pulse signal is broad due to the response performance of the first light receiving element 60 that receives light, and an accurate peak value cannot be measured. Therefore, the sample time T1 set in one pulse is detected. It is preferable to set the time when the pulse waveform in the vicinity before the falling edge of the pulse signal is stabilized.

Next, a current pulse train signal having a long pulse width of about 20 ns to 100 ns and an ON duty ratio of about 1 to 10% is input as described above, and in the pulse driving state in which the first pulse light is emitted from the semiconductor laser element 1, as shown in FIG. 4 (b), the second sample time T2, and the fourth sample time T 4, which is set to a different time from the rise time T0 of the pulse in one pulse (to have it, and T2 <T 4) The second light receiving element 62 measures the input / output characteristics and differential characteristics thereof. FIG output characteristics and its differential characteristics in sample time T2 to thereby measured 5 (a), respectively by the reference numeral C2, D2 (b), the addition, the input-output characteristic at sampling time T 4 and the differential characteristic Reference numerals C 4 and D 4 denote them, respectively.

Note that the second sample time T2 is the third sample time T 3 and time are equal time from the rising time T0, or the third sample time T 3 is shorter than the time from the rise time T0 time to be described later, it is set Rukoto preferably, also the fourth sample time T 4, it is preferable that the pulse waveform is set to fall before the vicinity of the time of the detection pulse signal is stable.

Then, the input-output characteristics C1 at sample time T1 measured by the first light receiving element 60 and the input-output characteristic C2, C 4 at sample time T2, T 4 that measured by differential characteristic D1, and the second light receiving element 62 based on the differential characteristic D2, D 4, to calculate the coupling efficiency CE of the main processor 12 and the semiconductor laser element 1 and the second light receiving element.

In particular, FIG. 5 (a), the second light receiving element output characteristic C2 at sample time T2, T 4 measured by 62, C 4 are matched and drive current having a linear Set the interval as the calculation interval. Here, the drive current section output characteristics C2, C 4 has a consistent and linearity, when input-output characteristic C2, C 4 has a perfectly matched and complete linearity not only, for example, if the differential value of the input-output differential characteristic in both time T2, T 4 (ΔP / ΔI ) ( i.e., the second derivative of the light output P Δ ² P / ΔI ²⁾ is within a predetermined range etc., it refers to a driving current interval output characteristics C2, C 4 are matched and judges has linearity, in the present embodiment to set the interval to Ib from the drive current Ia to the arithmetic section.

Then, in the operation section, and the average value SE1 of the input and output differential characteristic D1 at sample time T1 measured by the first light receiving element 60, output differential at sample time T2, T 4 measured by the second light receiving element 62 and the average value SE2 characteristics D2, D 4, calculates an average value SE1 of the input and output differential characteristic D1 of the average value SE2 of the input and output differential characteristic D2, D 4 by the second light receiving element 62 by the first light receiving element 60 By dividing, the coupling efficiency CE between the semiconductor laser element 1 and the second light receiving element is calculated.

Next, a current pulse train signal having a pulse width of about 3 ns to 20 ns corresponding to the actual use condition of the semiconductor laser element 1 is input, and in the short pulse driving state in which the second pulse light is emitted from the semiconductor laser element 1, FIG. as shown in c), by measuring the output characteristic of the third sample time T 3 set by the rise time T0 of the pulse at a predetermined time during one pulse by the second light receiving element 62, 6 input-output characteristic indicated by symbol C 3 is obtained.

Then, the main processor 12 receives the input-output input characteristic C 3 at sample time T 3 measured by the second light receiving element 62, the input-output characteristic C 3 by dividing the coupling efficiency CE described above, FIG. In FIG. 6, a calibrated input / output characteristic as indicated by reference numeral C5 is obtained.

  As described above, in the present invention, when detecting the input / output characteristics of the semiconductor laser element 1 in short pulse driving, the pulsed light output from the semiconductor laser element 1 is received by the second light receiving element 62 having a small light receiving area and high response performance. By measuring, the measurement error caused by the response performance of the light receiving element can be eliminated even with short pulse driving.

  Further, in a pulse driving state having a relatively long pulse width, the first light receiving element 60 that receives the entire light flux of the pulsed light emitted from the semiconductor laser element 1 and the second light receiving area that has a smaller light receiving area than the first light receiving element 60. The input / output characteristics and the differential characteristics thereof are measured by the two light receiving elements 60, 62 of the element 62, and the second light receiving element 62 measured based on the coupling efficiency CE of the second light receiving element 62 calculated from these measurement results. By calibrating the input / output characteristics of the semiconductor laser element 1 in pulse driving, accurate input / output characteristics can be detected even with the second light receiving element 62 having a small light receiving area.

Further, the second sample time T2 is set to the third sample time T 3 the same time or the third sample time shorter time than T 3, the time when the fourth sample time T 4 is a pulse waveform of the second detection pulse signal stabilizes due to the set, it is compared with the second sample time T2 the peak value of the fourth sample time T 4, to the second light receiving element 62 detects the pulsed light output during the short pulse drive of the It can be confirmed whether or not the response performance is sufficient. In other words, equal to the second sample time T2 fourth peak value sample time T 4, if the input and output characteristic curve C2, C 4 in both time T2, T 4 is determined to match, the rise time T0 of one pulse since the pulse waveform of the already second detection pulse signal at the time the second sample time T2 elapsed is stable, even in the third sample time T 3 set in the second sample time T2 the same as or slower time than the second Assuming that the pulse waveform of the detection pulse signal is stable, it can be confirmed that the second light receiving element 62 has sufficient response performance to detect the pulsed light output during short pulse driving.

  Note that there may be large variations in the spread angle of the light beam output from the device under test and the tilt angle of the optical axis. In such a case, the first light receiving device 60 and the second light receiving device 62 are switched for each device under test. The coupling efficiency CE may be calculated each time, whereby the coupling efficiency CE is calculated for each element to be inspected, and the input / output characteristics measured by the second light receiving element 62 can be accurately calibrated.

  Further, when the variation in the spread angle of the output light beam or the tilt angle of the optical axis is small, such as the device to be inspected in the same production lot in the mass production process, one or a plurality of devices to be inspected on behalf of every predetermined period The coupling efficiency CE may be calculated, and the input / output characteristics measured by the second light receiving element 62 within the predetermined period may be calibrated based on the calculated coupling efficiency CE, thereby calculating the coupling efficiency CE. Therefore, the tact time can be shortened.

1 is a block circuit diagram of an input / output characteristic detection apparatus for a semiconductor laser device according to a first embodiment of the present invention. It is a graph which shows the various signals in the current pulse train signal generation circuit of the input / output characteristic detection apparatus. It is a graph which shows the various signals in the photon detection circuit of the input-output characteristic detection apparatus. (A)-(c) is a graph which shows the detection pulse signal photoelectrically converted in the photon detection circuit. It is a graph which shows a measurement result by the input-output characteristic detection apparatus, (a) shows an input-output characteristic, (b) shows an input-output differential characteristic. It is a graph which shows the input / output characteristic detected by the input / output characteristic detection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Inspection apparatus 12 ... Main processor 20 ... Drive circuit 30 ... Current detection circuit 50 ... 1st light detection circuit 60 ... 1st light receiving element 62 ... 2nd light receiving element 70 ... 2nd light detection circuit

Claims (6)

(1) A first current pulse train signal having a first pulse width and a peak value increasing stepwise with a constant period is input to drive the semiconductor laser element, and (2) the first pulse emitted from the semiconductor laser element One pulse light is received by a first light receiving element having a light receiving surface capable of receiving all of the light fluxes, photoelectrically converted to obtain a first detection pulse signal, and (3) one pulse of the first detection pulse signal Detecting a first input / output characteristic indicating a change in a peak value of the first detection pulse signal with respect to a peak value of the first current pulse train signal at a first sample time set at a predetermined time from a rising time; (4) A first step of calculating a first input / output differential characteristic that is a differential characteristic of the first input / output characteristic;
  (1) The first pulse light is received by a second light receiving element having a light receiving surface smaller than the first light receiving element, photoelectrically converted to obtain a second detection pulse signal, and (2) the second detection pulse. A second input / output characteristic indicating a change in a peak value of the second detection pulse signal with respect to a peak value of the first current pulse train signal at a second sample time set at a predetermined time from a rising edge of one pulse of the signal; (3) a second step of calculating a second input / output differential characteristic that is a differential characteristic of the second input / output characteristic;
  A third step of calculating the coupling efficiency between the semiconductor laser element and the second light receiving element by dividing the second input / output differential characteristic by the first input / output differential characteristic;
  (1) driving a semiconductor laser element by inputting a second current pulse train signal having a second pulse width shorter than the first pulse width and increasing the peak value stepwise with a constant period; Second pulse light radiated from the semiconductor laser element is received by the second light receiving element, photoelectrically converted to obtain a third detection pulse signal, and (3) a rising point of one pulse of the third detection pulse signal A fourth step of detecting a third input / output characteristic indicating a change in the peak value of the third detection pulse signal with respect to the peak value of the second current pulse train signal at a third sample time set at a predetermined time from
  A fifth step of calibrating by dividing each value of the third input / output characteristic by the coupling efficiency, and setting the calibrated third input / output characteristic as the input / output characteristic of the semiconductor laser device;
  A method for detecting input / output characteristics of a semiconductor laser device, comprising:   In the second step, a fourth sample time is set at a predetermined time different from the second sample time from the rising edge of one pulse of the second detection pulse signal, and the wave of the first current pulse train signal at the fourth sample time is set. Detecting a fourth input / output characteristic indicating a change in peak value of the second detection pulse signal with respect to a high value and a fourth input / output differential characteristic which is a differential characteristic thereof;
  In the third step, (1) a current section in which the second input / output characteristic coincides with the fourth input / output characteristic and has linearity is set as a calculation section, and (2) the current section in the calculation section is set. An average value of the first input / output differential characteristic, and an average value of the second input / output differential characteristic and the fourth input / output differential characteristic are calculated, respectively. (3) the second input / output differential characteristic and the fourth The coupling efficiency is calculated by dividing the average value of the input / output differential characteristics by the average value of the first input / output differential characteristics.
  The input / output characteristic detection method for a semiconductor laser device according to claim 1. The second sample time is the time from the rise time of one pulse, the third sample time is equal time, or the third sample time shorter time, according to claim 1, characterized in that it is set to or 3. A method for detecting input / output characteristics of a semiconductor laser device according to 2. 4. The semiconductor laser device according to claim 1, wherein the first sampling time is set to a time at which a pulse waveform in the vicinity of the first detection pulse signal before the falling is stabilized. 5. I / O characteristics detection method. 5. The semiconductor laser device according to claim 2, wherein the fourth sample time is set to a time at which a pulse waveform in the vicinity of the second detection pulse signal before the falling is stabilized. 6. I / O characteristics detection method.   (1) A first current pulse train signal having a first pulse width and a peak value increasing stepwise with a constant period is input to drive the semiconductor laser element, and (2) the first pulse emitted from the semiconductor laser element One pulse light is received by a first light receiving element having a light receiving surface capable of receiving all of the light fluxes, photoelectrically converted to obtain a first detection pulse signal, and (3) one pulse of the first detection pulse signal Detecting a first input / output characteristic indicating a change in a peak value of the first detection pulse signal with respect to a peak value of the first current pulse train signal at a first sample time set at a predetermined time from a rising time; (4) A first calculation unit that calculates a first input / output differential characteristic that is a differential characteristic of the first input / output characteristic;
  (1) The first pulse light is received by a second light receiving element having a light receiving surface smaller than the first light receiving element, photoelectrically converted to obtain a second detection pulse signal, and (2) the second detection pulse. A second input / output characteristic indicating a change in a peak value of the second detection pulse signal with respect to a peak value of the first current pulse train signal at a second sample time set at a predetermined time from a rising edge of one pulse of the signal; (3) a second calculation unit that calculates a second input / output differential characteristic that is a differential characteristic of the second input / output characteristic;
  A third arithmetic unit that calculates the coupling efficiency between the semiconductor laser element and the second light receiving element by dividing the second input / output differential characteristic by the first input / output differential characteristic;
  (1) driving a semiconductor laser element by inputting a second current pulse train signal having a second pulse width shorter than the first pulse width and increasing the peak value stepwise with a constant period; Second pulse light radiated from the semiconductor laser element is received by the second light receiving element, photoelectrically converted to obtain a third detection pulse signal, and (3) a rising point of one pulse of the third detection pulse signal A fourth arithmetic unit for detecting a third input / output characteristic indicating a change in the peak value of the third detection pulse signal with respect to the peak value of the second current pulse train signal at a third sample time set at a predetermined time from
  A fifth arithmetic unit that calibrates each value of the third input / output characteristic by dividing by the coupling efficiency, and uses the calibrated third input / output characteristic as the input / output characteristic of the semiconductor laser element;
  A device for detecting input / output characteristics of a semiconductor laser device, comprising:

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