Laser diode device, method of operating a laser diode, and scanning microscope device equipped with a laser diode

Abstract

A laser diode device is provided, comprising a laser diode, a driver (EPS) for supplying AC power to the laser diode, a first feedback component (FB1), and a second feedback component (FB2). The first feedback component (FB1) is configured to detect an optical output of the laser diode and controls a first waveform characteristic of the AC power to adjust the detected optical output (P M ) as the first target value (P D ) The second feedback component (FB2) controls the temperature (T EST ) and controlling a second waveform characteristic of the AC power, which is different from the first waveform characteristic, to estimate the estimated temperature (T EST ) to the second target value (T OPT ) configured to maintain the temperature at or near the

Description

[Technical Field]

[0001] This application relates to a laser diode device. This application further relates to a method for operating a laser diode. This application further relates to a scanning microscope apparatus equipped with a laser diode. [Background technology]

[0002] Laser diodes have a wide range of applications. One example is their use in scanning probe microscopes (SPMs). In an SPM, a probe mounted on a flexible carrier scans along the surface of a sample. The deflection of light from the laser diode mounted on the flexible carrier is detected, and the detected signal is analyzed to measure the physical properties of the sample. At this stage, it is crucial that the light rendered by the laser diode is as stable as possible to minimize noise in the detected signal. Other applications include fiber optic communications, barcode readers, laser pointers, CD / DVD / Blu-ray disc reading / recording, laser printing, laser scanning, and ray illumination, all of which require a stable light beam.

[0003] In particular, when used in SPM (Surface-to-Plant Mechanism) equipment, high directional stability of the light beam is essential. In other words, the angular variation of the light beam must be small. [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The first object of this disclosure is to provide an improved laser diode device that reduces angular variation in the rendered laser beam.

[0005] A second object of this disclosure is to provide an improved method for operating a laser diode that reduces angular variation in the rendered laser beam.

[0006] A third object of this disclosure is to provide a scanning microscope apparatus equipped with an improved laser diode. [Means for solving the problem]

[0007] According to the first object, a laser diode apparatus is provided comprising a laser diode, a driver, a first feedback component, and a second feedback component, wherein the driver is configured to supply AC power to the laser diode having a first waveform characteristic and a second controlled waveform characteristic different from the first waveform characteristic.

[0008] The first feedback component includes an optical power control module configured to detect the optical output of a laser diode and to control a first waveform characteristic to maintain the detected optical output near a first target value.

[0009] The second feedback component includes a temperature control module configured to estimate the temperature of the laser diode by detecting the voltage-current characteristics of the laser diode, and to control the second waveform characteristics to maintain the estimated temperature near a second target value.

[0010] By estimating the laser diode temperature from the detected voltage-current characteristics, material costs are minimized. A separate temperature sensor is not required, nor are additional connections to such sensors necessary. Instead, a second feedback component can directly detect the voltage across the laser diode and the current flowing through it. In one example, the second feedback component includes a lookup table (LUT) with multiple addressable entries for each pair of voltage and current ranges, displaying the laser diode temperature values ​​associated with each pair of voltage and current ranges. In another example, the temperature value is estimated using an approximate polynomial relation specifying temperature as a function of measured voltage and current. In yet another example, the temperature is estimated using an analytical formula specifying temperature as a function of voltage and current.

[0011] Each feedback element controls one of the waveform characteristics, thereby maintaining both optical output and an operating temperature at which stable operation can be achieved.

[0012] In one embodiment, a first waveform characteristic controlled by the optical power control module of the first feedback component is the amplitude of a power parameter, and a second waveform characteristic controlled by the temperature control module of the second feedback component is the duty cycle. Thus, the optical power control module is configured to control a change in amplitude having a sign equal to the sign of the difference between a first target value and the detected optical output, and the temperature control module is configured to control a change in duty cycle having a sign equal to the sign of the difference between a second target value and the estimated temperature.

[0013] In an alternative embodiment, the first waveform characteristic controlled by the optical power control module of the first feedback component is the duty cycle of the power parameter, and the second waveform characteristic controlled by the temperature control module of the second feedback component is the amplitude. During operation, the optical power control module controls the first target value (P DThe temperature control module is configured to control a change in duty cycle having a sign equal to the sign of the difference between the second target value and the detected light output, and the temperature control module is configured to control a change in amplitude having a sign opposite to the sign of the difference between the second target value and the estimated temperature.

[0014] In some embodiments, the controlled amplitude is the amplitude of the current supplied to the laser diode. In this case, the voltage across the laser diode is a dependent parameter and is approximately proportional to the logarithm of the supplied current. In another embodiment, the controlled amplitude is the amplitude of the voltage supplied to the laser diode. In this case, the current flowing through the laser diode is a dependent parameter and is approximately proportional to the exponential function of the supplied voltage. Of these embodiments, direct control of the supply current has the advantage of being easier to stabilize at a constant value.

[0015] In some examples, the laser diode apparatus disclosed herein further comprises an optimal temperature calculation module configured to calculate a second target value, which is the optimal junction temperature at which the laser diode can produce an optical output equal to a first target value. In some applications, different optical outputs may be required depending on the circumstances. In practice, the optimal temperature at which Poynting stability is maximized will vary depending on the supplied optical output.

[0016] In one embodiment, the waveform to which power is applied is a square wave. This is advantageous in that it can be implemented with relatively simple power control components, namely, a controllable voltage or current source for controlling the amplitude of the square wave and a pulse width modulator for modulating the pulse width to which power is supplied can be implemented with controlled switching elements.

[0017] In another embodiment, the waveform to which power is applied is a sine wave. This operating mode is suitable for operation at high frequencies where the use of pulse-width modulation (PWM) signals is hindered by the parasitic input capacitance of the LD.

[0018] According to the second purpose of this disclosure, The power supply to the laser diode has a first waveform characteristic and a second waveform characteristic of the power parameters, Detecting the light output of a laser diode, The first waveform characteristic is controlled to maintain the detected optical output near the first target value, By detecting the voltage-current characteristics of the laser diode, we can estimate the temperature of the laser diode, A method is provided for operating a laser diode, which includes controlling a second waveform characteristic to maintain the estimated temperature near a second target value.

[0019] According to a third aspect of this disclosure, A probe with a tip that scans the surface of the sample, A signal generator that generates an input signal for inducing an acoustic signal to a probe, tip, or sample, One embodiment of the laser diode device described above generates a light ray emitted toward a probe and generates a secondary light ray reflected by the probe, A photodetector that outputs an output signal indicating the direction of the secondary ray, A scanning probe microscope (SPM) is provided, which includes a signal analysis module that outputs an output signal that describes the characteristics of a sample based on input and output signals.

[0020] An implementation of an SPM device might involve the SPM device's photodetector having the ability to detect the optical output of the laser diode, for example, by using the sum of the responses of the four quadrants of the photodetector. However, in practice, such a measurement method is not accurate in most applications because it is affected by cantilever movement, speckle interference, and the optical propagation medium. For example, in some applications, the SPM cantilever and sample are immersed in a liquid. For this reason, it is usually preferable to place a dedicated optical output sensor near the laser diode. Typically, the laser diode is housed in the same package as such a sensor.

[0021] The embodiments described above and other embodiments will be explained in more detail with reference to the drawings. [Brief explanation of the drawing]

[0022] [Figure 1] This diagram schematically shows a first embodiment of a laser diode device. [Figure 2] This diagram schematically shows a second embodiment of the laser diode device. [Figure 3] This diagram schematically shows a third embodiment of the laser diode device. [Figure 4] This diagram schematically shows a fourth embodiment of the laser diode device. [Figure 5] This diagram schematically shows a fifth embodiment of the laser diode device. [Figure 6] This diagram schematically shows a sixth embodiment of the laser diode device. [Figure 7] This is a schematic diagram of a scanning probe microscope (SPM) system. [Figure 8] This figure shows the measurement results obtained using a controlled-drive laser diode. [Modes for carrying out the invention]

[0023] Unless otherwise stated, the same reference numerals in each drawing refer to the same elements.

[0024] The following detailed description includes many specific details to enable a full understanding of the present invention. However, it will be understood by those skilled in the art that the present invention can be carried out without these specific details. In some cases, well-known methods, procedures, and components are not described in detail so as not to obscure aspects of the present invention.

[0025] FIG. 1 is a diagram schematically showing a laser diode device. This device includes a laser diode LD, and the laser diode LD is connected to a driver EPS. The driver EPS is configured to supply the laser diode LD with AC power having a first controlled waveform characteristic of power parameters and a second controlled waveform characteristic different from the first controlled waveform characteristic. The laser diode device further includes a first feedback component FB1 and a second feedback component FB2.

[0026] The first feedback component FB1 is configured to detect the optical output of the laser diode LD, and has an optical power control module OPCM configured to control the first waveform characteristic to maintain the detected optical output P M near a first target value P D In the illustrated example, the first feedback component FB1 includes a monitor diode MD disposed near the laser diode LD and housed together with the laser diode LD in, for example, a common package. A subtraction element such as a differential amplifier calculates the difference E D between the first target value P M and the detected optical output P P , which is output as an input to the optical power control module OPCM. In response, the optical power control module OPCM outputs a control signal C A for controlling the first waveform characteristic of the power parameters, and the driver EPS supplies the laser diode LD with AC power together with this first waveform characteristic. The first target value P D is set, for example, by an operator or a chief administrator.

[0027] The second feedback component FB2 is configured to estimate the temperature T EST of the laser diode LD by detecting the voltage-current characteristic of the laser diode LD, and controls the second waveform characteristic to maintain the estimated temperature T EST near a second target value T OPTIt has a temperature control module (TCM) configured to be maintained nearby. In the illustrated embodiment, the second feedback component FB2 includes a voltage sensor SV that detects the voltage drop across the laser diode LD, and the voltage sensor SV outputs a signal V indicating the detected value. LD The output signal is sent to the temperature estimation module TEM. Furthermore, the driver EPS outputs an output signal I indicating the current supplied to the laser diode LD. LD The output signal V is sent to the temperature estimation module TEM. In some examples, the output signal V LD and output signal I LD These represent the instantaneous voltage across the laser diode LD and the instantaneous current flowing through the laser diode LD, respectively. In other examples, the output signal V LD and output signal I LD This indicates, for example, the respective peak values ​​or their respective average values. The temperature estimation module TEM outputs the V LD and output signal I LD Based on the detected voltage-current characteristics shown, the actual junction temperature of the laser diode LD is estimated. In response, a temperature indicator signal T showing the estimated temperature value is issued. EST The output is as follows: In the illustrated example, the temperature estimation module TEM has a lookup table with multiple addressable entries for each pair of voltage ranges and current ranges.

[0028] Subtractive elements such as differential amplifiers use the signal T OPT The second target value T is the junction temperature value at which stable operation is achieved, as indicated by [the formula]. OPT And, signal T EST The difference E from the estimated temperature shown by T The second target value T is calculated. In the illustrated example, the second target value T is calculated. OPT For example, the laser diode LD reaches the first target value P D An optimal temperature calculation module (OTCM) is provided, configured to calculate the optimal junction temperature at which an optical output equal to T can be produced. In an alternative embodiment, for example, if the output can only be selected within a relatively narrow range, a second target value T OPT A fixed value is specified.

[0029] In the embodiment shown in Figure 1, the power parameter to be controlled is the current supplied to the laser diode LD. The first waveform characteristic controlled by the optical power control module OPCM of the first feedback component FB1 is the amplitude of the supplied current. During operation, the optical power control module OPCM controls a first target value P D The detected light output P M The difference E P Control the amplitude change having a sign equal to the sign of the target. For example, target optical output P D The detected light output P M If it exceeds this value, the driver EPS supplies a current with increased amplitude.

[0030] The second waveform characteristic controlled by the temperature control module TCM of the second feedback component FB2 is current I PWM This is the duty cycle for which the power is supplied. During operation, the temperature control module (TCM) sets the second target value T. OPT The temperature T was estimated to be EST The difference E T Control the change in the duty cycle, which has a sign equal to the sign of . For example, the estimated temperature T EST The second target value is T OPT If it is higher than, the difference E TThe sign of is negative, and the temperature control module (TCM) reduces the duty cycle. This means a decrease in optical output, but typically the first feedback component FB1 can compensate for the optical power relatively quickly compared to the changes caused by changes in the duty cycle due to temperature changes. This is because the junction temperature is related to the integral of the power consumed there, and is directly related to the power supplied by the optical output. However, the response speeds of the first feedback component FB1 and the second feedback component FB2 may be set as appropriate if necessary. For example, the first feedback component FB1 may be a proportional-derivative (PD) controller with a differential component D added to the proportional component P to increase the response speed, and / or the second feedback component FB2 may be a proportional-integral (PI) controller with an integral component I added to the proportional component P to decrease the response speed.

[0031] Furthermore, it should be noted that the laser diode device may include a feedforward control module that specifies reference values ​​for amplitude and duty cycle based on prior estimations. In this case, the first feedback component FB1 and the second feedback component FB2 specify adaptations to their respective reference values ​​to approximate target operating temperature and target optical power.

[0032] In the embodiment shown in Figure 1, the controlled amplitude is the amplitude of the current supplied to the laser diode LD. In this case, the voltage across the laser diode LD is a dependent parameter and is approximately proportional to the logarithm of the supplied current according to the response characteristics of the laser diode LD.

[0033] Figure 2 shows another embodiment corresponding to the embodiment in Figure 1, except that the controlled amplitude is the amplitude of the voltage supplied to the laser diode LD. In this case, the output signal C of the optical power control module OPCM... AThis is the pulse width modulated voltage V supplied to the laser diode LD by the driver EPS. PWM Specify the amplitude.

[0034] In this case, the current flowing through the laser diode LD is a dependent parameter and is approximately proportional to the exponential function of the supplied voltage. Of these embodiments, direct control of the supply current has the advantage of being able to stabilize a constant value more easily.

[0035] Figure 3 shows yet another embodiment. Similar to the embodiment in Figure 1, the driver EPS controls the controlled pulse width modulation current I PWM This is supplied to the laser diode LD. However, in this case, the optical power control module OPCM of the first feedback component FB1 controls the duty cycle of the current, and the second feedback component FB2 controls the amplitude of the current.

[0036] During operation, the optical power control module (OPCM) sets the first target value P D The detected light output P M The difference E P Control the change in the duty cycle, which has a sign equal to the sign of [the specified value]. For example, the detected light output P M The first target value is P D If it is smaller, the difference E P The sign is positive, and the optical power control module (OPCM) controls the positive change in the duty cycle.

[0037] During operation, the temperature control module (TCM) sets the second target value T OPT The temperature T was estimated to be EST The difference E T Control the amplitude change which has the opposite sign to the sign of the given value. For example, the estimated temperature T EST The second target value is T OPT It falls below, difference E T If the sign is positive, the temperature control module (TCM) controls the driver EPS to produce a lower amplitude pulse width modulated current I PWM It supplies the following. If the first feedback component FB1 is not present, the junction temperature will be the second target value T.OPT It is expected that the output will decrease even further, but because the response of the optical power control module OPCM is relatively fast, the duty cycle increases and the specified output is maintained. Therefore, due to the combined effect of the first feedback component FB1 and the second feedback component FB2, a constant value is achieved with a lower amplitude and a larger duty cycle, and as a result the junction temperature rises, and the second target value T OPT We can get even closer to that goal.

[0038] Figure 4 shows another embodiment corresponding to the embodiment in Figure 3, except that the controlled amplitude is the amplitude of the voltage supplied to the laser diode LD.

[0039] Further details of the embodiment shown in Figure 2 are shown in Figure 5. As shown there, the driver EPS is a controllable voltage supply module EPS V and controllable pulse width modulator module EPS DC It includes a controllable voltage supply module EPS. V The input voltage V is from an external power source such as a battery. IN Receiving the amplitude control signal C A A pulse width modulator module (EPS) capable of controlling voltage according to the specified parameters. DC It supplies to this. In response, a controllable pulse width modulator module EPS DC This is the duty cycle control signal C DC A controlled voltage with a duty cycle specified by is supplied to the laser diode LD. Note that, due to the presence of the sense resistor SR, the amplitude of the voltage across the laser diode LD is slightly smaller than the amplitude due to the driver EPS. In practice, this is not a problem because the two feedback components FB1 and FB2 tend to control the driver EPS in any case so that the target operating temperature and target optical power are achieved.

[0040] Further details of the embodiment shown in Figure 3 are shown in Figure 6. As shown there, the driver EPS is a controllable pulse width modulator module EPSDC and controllable current supply module EPS I It includes a controllable pulse width modulator module EPS. DC The input voltage V is from an external power source such as a battery. IN Upon receiving the duty cycle control signal C DC A current supply module (EPS) capable of controlling a controlled pulse-width modulated supply voltage with a duty cycle specified by [the specified method]. I It supplies power to the controllable current supply module EPS. I This is the amplitude control signal C A Amplitude and pulse width modulator module EPS controlled by DC A current with a pulse width modulated by is supplied to the laser diode LD.

[0041] Figure 7 is a schematic diagram of a scanning probe microscope (SPM) system comprising a probe P, a signal generator SG, an optical laser diode apparatus LDC, a laser diode LD, a photodetector DT, and a signal analysis module AM. The optical laser diode apparatus LDC and laser diode LD are, for example, one embodiment as shown in Figures 1 to 6. Here, the controlled laser driver LDC is a combination of a driver EPS, a first feedback component FB1, and a second feedback component FB2. The interconnection between the block LDC and the laser diode LD represents the power supply line to the laser diode LD and the output from the photosensor MD, which is integrated with the laser diode LD in a common package. A separate temperature sensor line is not required because the second feedback component FB2 is configured to estimate the junction temperature from the voltage-current characteristics of the laser diode LD.

[0042] In an SPM device, the probe P has a tip T that scans the surface of the sample S. The tip T is provided, for example, on a cantilever, membrane, or other flexible carrier. The signal generator SG receives the input signal S inIt is provided to generate a secondary ray B and guide an acoustic signal to the probe P, tip T, or sample S. The laser diode LD is configured to generate a stable ray B emitted toward the probe P. As a result, the secondary ray Br is reflected by the probe P and detected by a photodetector DT such as a quadrant detector. In response, the photodetector DT outputs an output signal S indicating the direction of the secondary ray Br. out The output is as follows: Since the secondary ray Br arises from the reflection of the original ray B on probe P, the detected direction indicates the deformation of probe P, and thus reveals the surface or subsurface features of sample S. Accordingly, the signal analysis module AM ​​analyzes the input signal S in and output signal S out Based on this, an output signal San is output that characterizes sample S. The controlled laser driver LDC drives the laser diode LD so that the laser diode LD generates a stable output beam B of controlled power, thereby producing the output signal S out This minimizes noise.

[0043] Figure 8 shows the results obtained from a series of 400 measurements performed using an HL6320G TO-9 laser diode. For this experiment, the laser diode temperature was increased in 400 steps of 0.005°C in the range of 23 to 25°C. In each of the 400 measurements, the output was swept from 0.2 mW to 2.7 mW. The noise level of the laser diode at each temperature and output combination was measured using a quad cell.

[0044] The left side of Figure 8 shows the measured noise level in arbitrary units. The vertical axis represents the number of measurements, and the horizontal axis represents the output in units of mW. Brightness indicates the measured noise level. The right side of Figure 8 shows the temperature set for each measurement on the horizontal axis and the number of measurements on the vertical axis. It can be seen that reducing position noise is difficult when operating at low output, e.g., less than 0.3mW. However, above this output level, noise can be minimized by appropriately controlling the junction temperature. For example, when the output is 1.0mW, the temperature should be maintained within the range of approximately 23.8°C to 24.5°C. When the output is 2.5mW, the temperature should be maintained within the range of approximately 23.3°C to 24.1°C.

[0045] Although the present invention has been described in a limited number of embodiments, those skilled in the art will understand that many modifications and variations exist within the scope of the invention as defined by the appended claims. In the claims, the word “including” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude plurals. A single component or other unit may perform the function of several items described in the claims. The mere fact that certain means are described in different claims does not mean that combinations of these means cannot be used advantageously. No reference numeral in the claims should be construed as limiting the scope of the invention. Furthermore, in one aspect, the present invention may be configured as follows. [Section 1] Laser diode (LD) and, A driver (EPS) that supplies AC power having a first controlled waveform characteristic and a second controlled waveform characteristic of power parameters to a laser diode (LD), wherein the second controlled waveform characteristic is different from the first controlled waveform characteristic of the driver (EPS), The system is configured to detect the optical output of the laser diode (LD), and the first waveform characteristic is controlled to detect the optical output (P M ) to the first target value (P DA first feedback component (FB1) having an optical power control module (OPCM) configured to maintain near By detecting the voltage-current characteristics of the laser diode (LD), the temperature (T EST ) of the laser diode (LD) is estimated, and the second waveform characteristic is controlled to estimate the temperature (T EST ) is maintained near a second target value (T OPT ) A second feedback component (FB2) having a temperature control module (TCM) configured to control the temperature of the laser diode device. [Item 2] The first waveform characteristic controlled by the optical power control module (OPCM) of the first feedback component (FB1) is the amplitude of the power parameter, and the optical power control module (OPCM) is the first target value (P D ) and the detected optical output (P M ) and the difference (E P ) is configured to control a change in amplitude having the same sign as the sign of The second waveform characteristic controlled by the temperature control module (TCM) of the second feedback component (FB2) is the duty cycle, and the temperature control module (TCM) is the second target value (T OPT ) and the estimated temperature (T EST ) and the difference (E T ) is configured to control a change in duty cycle having the same sign as the sign of the optical laser diode device according to Item 1. [Item 3] The first waveform characteristic controlled by the optical power control module (OPCM) of the first feedback component (FB1) is the duty cycle of the power parameter, and the optical power control module (OPCM) is the first target value (P D ) and the detected optical output (P M ) and the difference (E P ) is configured to control a change in duty cycle having the same sign as the sign of The second waveform characteristic controlled by the temperature control module (TCM) of the second feedback component (FB2) is amplitude, and the temperature control module (TCM) is the second target value (T OPT ), and the estimated temperature (T EST ), and the change in amplitude having a sign opposite to the sign of the difference (E T ) is controlled. The optical laser diode device according to claim 1. [Item 4] The controlled amplitude is the amplitude of the current supplied to the laser diode (LD). The optical laser diode device according to claim 2 or 3. [Item 5] The controlled amplitude is the amplitude of the voltage supplied to the laser diode (LD). The optical laser diode device according to claim 2 or 3. [Item 6] The laser diode (LD) is further provided with an optimum temperature calculation module (OTCM) configured to calculate the optimum junction temperature at which the laser diode (LD) can generate an optical output with an output equal to the first target value (P D ) as the second target value (T OPT ). The optical laser diode device according to any one of Items 1 to 5. [Item 7] Supplying AC power having a first controlled waveform characteristic and a second controlled waveform characteristic of power parameters to a laser diode (LD), wherein the second controlled waveform characteristic is different from the first controlled waveform characteristic, Detecting the optical output of the laser diode (LD), Controlling the first waveform characteristic to maintain the detected optical output (P M ) near the first target value (P<surrogate id="0000100">), Estimating the temperature (T EST ) of the laser diode (LD) by detecting the voltage-current characteristics of the laser diode (LD), Controlling the second waveform characteristic to make the estimated temperature (T EST ) the second target value (TOPT A method for operating an optical laser diode, including maintaining it in the vicinity of ). [Section 8] The first controlled waveform characteristic is the amplitude of the power parameter, The controlled change in amplitude is the first target value (P D ) and the detected light output (P M The difference (E) P It has a sign equal to the sign of ) The second controlled waveform characteristic is the duty cycle, The controlled change in the duty cycle is the second target value (T OPT ) and the estimated temperature (T EST The difference (E) T The method according to claim 7, having a sign equal to the sign of ). [Section 9] The first controlled waveform characteristic is the duty cycle of the power parameter, The controlled change in the duty cycle is the first target value (P D ) and the detected light output (P M The difference (E) P It has a sign equal to the sign of ) The controlled waveform characteristic of the latter is amplitude. The controlled change in the amplitude is the second target value (T OPT ) and the estimated temperature (T EST The difference (E) T The method according to item 8, wherein the sign is the opposite of the sign of ). [Section 10] The method according to claim 8 or 9, wherein the controlled amplitude is the amplitude of the current supplied to the laser diode (LD). [Section 11] The method according to claim 8 or 9, wherein the controlled amplitude is the amplitude of the voltage supplied to the laser diode (LD). [Section 12] The laser diode (LD) is the first target value (P D The optimal junction temperature that can generate an optical output equal to the second target value (T) is defined as the second target value (T)OPT The method described in any one of items 7 through 11, further comprising calculating as follows: [Section 13] A probe (P) having a tip (T) that scans the surface of a sample (S), An input signal (S) for inducing an acoustic signal to the probe (P), the tip (T), or the sample (S) in A signal generator (SG) that generates ) and A laser diode device according to any one of items 1 to 6, which generates a light ray (B) emitted toward the probe (P) and generates a secondary light ray (Br) reflected by the probe (P), The output signal (S) indicates the direction of the secondary ray (Br). out A photodetector (DT) that outputs ) and The aforementioned input signal (S in ) and the output signal (S out A scanning probe microscope (SPM) apparatus comprising a signal analysis module (AM) that outputs an output signal (San) that shows the characteristics of the sample (S) based on ).

Claims

1. Laser diode (LD) and, A driver (EPS) that supplies AC power having a first controlled waveform characteristic and a second controlled waveform characteristic of power parameters to a laser diode (LD), wherein the second controlled waveform characteristic is different from the first controlled waveform characteristic of the driver (EPS), The system is configured to detect the optical output of the laser diode (LD), and the first controlled waveform characteristic is controlled to detect the optical output (P Ｍ ) set to the first target value (P Ｄ A first feedback component (FB1) having an optical power control module (OPCM) configured to maintain equal to ), By detecting the voltage-current characteristics of the laser diode (LD), the temperature of the laser diode (LD) is determined (T ＥＳＴ The system is configured to estimate the temperature (T) and to control the second controlled waveform characteristic to estimate the temperature (T) ＥＳＴ ) to the second target value (T ＯＰＴ An optical laser diode apparatus comprising a second feedback component (FB2) having a temperature control module (TCM) configured to maintain equal to ).

2. The first controlled waveform characteristic controlled by the optical power control module (OPCM) of the first feedback component (FB1) is the amplitude of the power parameter, and the optical power control module (OPCM) controls the first target value (P Ｄ ) and the detected light output (P Ｍ ) difference (E Ｐ It is configured to control the amplitude change having a sign equal to the sign of ), The second controlled waveform characteristic controlled by the temperature control module (TCM) of the second feedback component (FB2) is a duty cycle, and the temperature control module (TCM) is the second target value (T ＯＰＴ ), and the estimated temperature (T ＥＳＴ ), and the duty cycle change having a sign equal to the sign of the difference (E Ｔ ). The laser diode device according to claim 1, which is configured to control the change of the duty cycle.

3. The first controlled waveform characteristic controlled by the optical power control module (OPCM) of the first feedback component (FB1) is the duty cycle of the power parameter, and the optical power control module (OPCM) controls the first target value (P Ｄ ) and the detected light output (P Ｍ ) difference (E Ｐ It is configured to control changes in the duty cycle having a sign equal to the sign of ), The second controlled waveform characteristic controlled by the temperature control module (TCM) of the second feedback component (FB2) is amplitude, and the temperature control module (TCM) controls the second target value (T ＯＰＴ ) and the estimated temperature (T ＥＳＴ ) difference (E Ｔ The optical laser diode apparatus according to claim 1, configured to control changes in amplitude having the opposite sign to the sign of ).

4. The optical laser diode apparatus according to claim 2 or 3, wherein the controlled amplitude is the amplitude of the current supplied to the laser diode (LD).

5. The optical laser diode apparatus according to claim 2 or 3, wherein the controlled amplitude is the amplitude of the voltage supplied to the laser diode (LD).

6. The laser diode (LD) reaches the first target value (P Ｄ The optimal junction temperature that can generate an optical output equal to the second target value (T) is defined as the second target value (T). ＯＰＴ The optical laser diode apparatus according to any one of claims 1 to 3, further comprising an optimal temperature calculation module (OTCM) configured to calculate as ).

7. The method of supplying AC power having a first controlled waveform characteristic and a second controlled waveform characteristic of power parameters to a laser diode (LD), wherein the second controlled waveform characteristic is different from the first controlled waveform characteristic, The optical output of the laser diode (LD) is detected, The optical output (P) detected by controlling the first controlled waveform characteristic Ｍ ) set to the first target value (P Ｄ ) to be maintained in equal terms, By detecting the voltage-current characteristics of the laser diode (LD), the temperature of the laser diode (LD) is determined (T ＥＳＴ ) to estimate, The estimated temperature (T) is obtained by controlling the second controlled waveform characteristic. ＥＳＴ ) to the second target value (T ＯＰＴ A method for operating an optical laser diode, including maintaining it equal to ).

8. The first controlled waveform characteristic is the amplitude of the power parameter, The controlled change in amplitude is the first target value (P Ｄ ) and the detected light output (P Ｍ ) difference (E Ｐ ) has a sign equal to the sign of, The second controlled waveform characteristic is the duty cycle, The controlled change in the duty cycle is the second target value (T ＯＰＴ ) and the estimated temperature (T ＥＳＴ ) difference (E Ｔ The method according to claim 7, wherein the sign is equal to the sign of ).

9. The first controlled waveform characteristic is the duty cycle of the power parameter, and the controlled change in the duty cycle is the first target value (P Ｄ ) and the detected light output (P Ｍ ) difference (E Ｐ ) has a sign equal to the sign of, The controlled waveform characteristic of the second term is amplitude, The controlled change in the amplitude is the second target value (T ＯＰＴ ) and the estimated temperature (T ＥＳＴ ) difference (E Ｔ The method according to claim 7, wherein the symbol has the opposite sign to the symbol of ).

10. The method according to claim 8 or 9, wherein the controlled amplitude is the amplitude of the current supplied to the laser diode (LD).

11. The method according to claim 8 or 9, wherein the controlled amplitude is the amplitude of the voltage supplied to the laser diode (LD).

12. The laser diode (LD) reaches the first target value (P Ｄ The optimal junction temperature that can generate an optical output equal to the second target value (T) is defined as the second target value (T). ＯＰＴ The method according to any one of claims 7 to 9, further comprising calculating as follows:

13. A probe (P) having a tip (T) that scans the surface of a sample (S), An input signal (S) for inducing an acoustic signal to the probe (P), the tip (T), or the sample (S). ｉｎ A signal generator (SG) that generates ) and A laser diode device according to any one of claims 1 to 3, which generates a light ray (B) emitted toward the probe (P) and generates a secondary light ray (Br) reflected by the probe (P), The output signal (S) indicating the direction of the secondary ray (Br) ｏｕｔ A photodetector (DT) that outputs ) and The aforementioned input signal (S ｉｎ ) and the output signal (S ｏｕｔ A scanning probe microscope (SPM) apparatus comprising: a signal analysis module (AM) that outputs an output signal (San) that shows the characteristics of the sample (S) based on );

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