WO2006114842A1 - レーザ装置 - Google Patents
レーザ装置 Download PDFInfo
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- WO2006114842A1 WO2006114842A1 PCT/JP2005/006911 JP2005006911W WO2006114842A1 WO 2006114842 A1 WO2006114842 A1 WO 2006114842A1 JP 2005006911 W JP2005006911 W JP 2005006911W WO 2006114842 A1 WO2006114842 A1 WO 2006114842A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/23—Arrangements of two or more lasers not provided for in groups H01S3/02 - H01S3/22, e.g. tandem arrangements of separate active media
- H01S3/2308—Amplifier arrangements, e.g. MOPA
- H01S3/2316—Cascaded amplifiers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
- H01S3/1123—Q-switching
- H01S3/117—Q-switching using intracavity acousto-optic devices
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
- H01S3/1123—Q-switching
- H01S3/127—Plural Q-switches
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S2301/00—Functional characteristics
- H01S2301/02—ASE (amplified spontaneous emission), noise; Reduction thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
- H01S3/0057—Temporal shaping, e.g. pulse compression, frequency chirping
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
- H01S3/0085—Modulating the output, i.e. the laser beam is modulated outside the laser cavity
Definitions
- the present invention relates to a laser device having a MOPA configuration.
- spontaneous emission occurs between various levels as a result of excitation by the amplifier and is output.
- Stimulated emission is generated and amplified with respect to the spontaneous emission light, and light is output in the same direction as the direction in which the originally necessary laser light travels or in the opposite direction. This light is called natural amplified light.
- this naturally amplified light is incident on an adjacent amplifier, the gain of the amplifier is further deprived and amplified, so that there is a problem that the output of the laser light that is originally required decreases.
- a communication MOPA-configured laser device including a low energy oscillator includes an acousto-optic modulator inserted between amplifiers (see, for example, Patent Document 1). ).
- a laser device having a resonator in an amplifier unlike a laser device having a MOPA configuration, there is a laser device having a resonator in an amplifier.
- the continuous wave laser beam oscillated in the unstable resonator is obtained.
- There is a high-power cannula laser device that delays the on-timing of the amplifier Q switch from the on-timing of the oscillator Q switch in order to suppress leaking into the oscillator and taking the gain of the oscillator see, for example, Patent Document 2).
- Patent Document 1 Japanese Patent Laid-Open No. 10-268369
- Patent Document 2 Japanese Patent Laid-Open No. 2001-308427
- a plurality of amplifiers are collectively referred to as an amplification stage.
- the oscillator is also called an oscillation stage as appropriate.
- the timing at which the Q switch of the amplification stage opens is set in the oscillation stage as described in Patent Document 2.
- Naturally amplified light from the amplification stage can be suppressed by delaying the opening of the Q switch. This will be explained below using FIG.
- FIG. 13 shows temporal changes of the resonator loss of the oscillation stage, the laser gain, the pulse laser waveform output from the oscillation stage force, and the Q switch loss of the amplification stage.
- the resonator loss is the sum of the loss in the partially reflecting mirror composing the resonator and the loss of the Q switch in the resonator. Since the loss of the partial reflector is always constant, the amount of change in the resonator loss depends on the amount of change in the Q switch loss.
- the gain of the low energy oscillation stage is generally low.
- the rise of the laser gain becomes a slow force, and from the point T1 when the Q switch of the oscillation stage opens, the resonator loss force S laser gain A certain amount of time will be required by the point ⁇ 3.
- the growth of pulsed laser light starts from ⁇ 3, but when the gain is low, the growth speed is slow and the build-up time is relatively long. Therefore, by delaying T2 from T1, the Q switch in the amplification stage can be closed until the panorless laser light reaches the amplification stage, so that naturally amplified light enters the other amplifier before it reaches the pulsed laser light. Decreasing the gain of the amplification stage can be suppressed.
- a laser processing apparatus used for processing or the like has recently required high energy. Therefore, there has been a demand for a laser device capable of high energy output with a MOPA configuration. In order to realize such a laser device, it is indispensable to develop a high gain laser oscillator.
- the inventor developed a MOPA configuration by developing a phenomenon in which the time from T1 to T3 and the build-up time b are shortened as the gain of the laser oscillator increases in developing a high-gain laser oscillator. We found the following problems in the laser equipment.
- FIG. 14 shows time variations of the resonator loss of the oscillation stage, the laser gain, the pulse laser waveform output from the oscillation stage, and the Q switch loss of the amplification stage when the laser oscillator has a high gain.
- T1 to T6 in FIG. 14 indicate the same time points as in FIG.
- the rise of the laser gain is steep, so the time from when the Q switch opens until the resonator loss reaches the laser gain, that is, Tl — The distance between ⁇ 3 is shortened. Also, if the power gain at which the pulse laser beam begins to grow from ⁇ 3 is high, the growth rate is fast and the build-up time is short and b is also short. Therefore, a phenomenon occurs in which the growth of the pulsed laser beam ends by T4, that is, the output of the pulsed laser beam from the oscillation stage is completed.
- the time between T1 and T6 becomes shorter, and the pulse laser beam incident power ST2 before the amplification stage ST2, that is, before the Q switch of the amplification stage is opened, the laser light is amplified. Therefore, there is a problem that the pulse laser beam does not enter the amplification stage and the laser is not emitted from the amplification stage.
- the time from when the Q switch of the amplification stage starts to open until it fully opens is the time from T2 to T5 (hereinafter referred to as the fall time ⁇ f) is the time for the pulse laser beam to grow. That is, it may be shorter than the time between T1 and T6.
- FIG. 15 shows time changes such as the resonator loss of the oscillation stage when the fall time ⁇ ⁇ is 0.
- the pulsed light enters the amplification stage after the Q switch of the amplification stage is fully opened. It's pretty cute.
- an acousto-optic device (hereinafter referred to as an AZO device) is an example of a high-speed Q switch that can withstand high energy. It works as a switching element by utilizing the fact that it acts as a diffraction grating when ultrasonic waves travel inside the AZO element.
- the fall time ⁇ f in the case of the AZO element Q switch is the time for traversing the beam diameter of the laser beam transmitted through the AZO element Q switch in the AZO element Q switch.
- the laser light cannot be reduced extremely to prevent damage to the optical system, and can only be reduced to about lmm at most. Since the speed of the sound wave in the AZO element is about 6 kmZs, the time for the sound wave to cross the beam diameter of the laser light is about 200 ns.
- the time between T1 and T6 reaches a level of several tens of ns, and the fall time can only be shortened to several times the time during which the pulse laser beam grows (between T1 and T6). is there. That is, the state shown in FIG. 14 is maintained.
- a laser device having a high configuration includes, for example, a high-gain high-energy Q-switch laser oscillator.
- Q switch opens and the force The time force until the pulse laser beam grows and begins to be output from the laser oscillator If the fall time ⁇ f of the amplification stage Q switch is short, the output of the naturally amplified light generated in the amplification stage The purpose is to prevent loss of pulsed laser light at the Q switch of the amplification stage while suppressing the decrease.
- a Q switch is provided in the resonator, and a laser oscillator that outputs pulsed laser light by turning on and off the Q switch, and a pulse output from the laser oscillator
- the laser Q switch In order to amplify the laser, one or a plurality of amplifiers arranged along the optical axis of the pulsed laser beam, and at least one place between the oscillator and the amplifier or between the amplifiers, the laser Q switch that gates on a predetermined time earlier than the gate on timing of the oscillator Q switch.
- the gate on timing of the Q switch of the laser oscillator is set to be delayed by a predetermined time from the gate on timing of the Q switch of the amplification stage.
- the loss of the pulsed laser light in the Q switch of the amplification stage can be suppressed while maintaining the decrease in the gain of the amplifier and the oscillator due to the above, and the laser output can be prevented from decreasing.
- FIG. 1 is a configuration diagram of a laser apparatus showing Embodiment 1 of the present invention.
- FIG. 2 is a graph showing a time change of a signal for controlling the operation of the Q switch of the laser apparatus in the first embodiment of the present invention.
- FIG. 3 The oscillation loss of the oscillation stage, the laser gain, the oscillation stage force of the laser apparatus equipped with the high gain laser oscillator in the first embodiment of the present invention, and the Q switch of the amplification stage It is a graph which shows the time change of loss.
- FIG. 4 is another configuration diagram of the laser apparatus showing the first embodiment of the present invention.
- FIG. 5 is another configuration diagram of the laser apparatus showing the first embodiment of the present invention.
- FIG. 6 The resonator loss of the oscillation stage, the laser gain, the oscillation stage force of the laser device provided with the low gain laser oscillator in Embodiment 1 of the present invention, and the pulse laser waveform output, and the Q switch of the amplification stage It is a graph which shows the time change of loss.
- FIG. 7 is a graph showing changes over time in the resonator loss of the oscillation stage, the laser gain, the pulse laser waveform output from the oscillation stage, and the Q switch loss in the amplification stage of the laser device according to Embodiment 2 of the present invention. is there.
- FIG. 8 is a configuration diagram of a Q switch of the laser apparatus in the third embodiment of the present invention.
- FIG. 9 is a diagram for explaining the operation of the Q switch of the laser apparatus in the third embodiment of the present invention.
- FIG. 10 is a graph showing temporal changes of the resonator loss of the oscillation stage and the Q switch loss of the amplification stage of the laser apparatus in the third embodiment of the present invention.
- FIG. 11 is a configuration diagram of a laser apparatus showing Embodiment 4 of the present invention.
- FIG. 12 The laser light and the naturally amplified light of the laser apparatus in the embodiment 4 of the present invention. It is a figure which shows a beam profile.
- FIG. 13 This figure shows the time variation of the oscillation loss of the oscillation stage, laser gain, pulse laser waveform output from the oscillation stage, and Q switch loss of the amplification stage in a laser apparatus equipped with a conventional low gain laser oscillator. It is a graph.
- FIG. 14 This figure shows the time variation of the resonator loss of the oscillation stage, laser gain, pulse laser waveform output from the oscillation stage, and Q switch loss of the amplification stage in a laser apparatus equipped with a conventional high gain laser oscillator. It is a graph.
- FIG. 15 In a laser apparatus equipped with a conventional high-gain laser oscillator, when the foul time of the Q switch of the amplification stage is assumed to be 0, output is made from the resonator loss of the oscillation stage, laser gain, and oscillation stage 5 is a graph showing a time change of a pulse laser waveform and Q switch loss of an amplification stage.
- FIG. 1 shows a laser apparatus according to Embodiment 1 for carrying out the present invention, which has a MOPA configuration having an oscillation stage having one oscillator and an amplification stage having three amplifiers.
- 16a is an oscillation stage laser medium
- 16b, 16c and 16d are amplification stage laser media
- 19a to d are excitation sources for exciting the laser media 16a to d, respectively.
- the discharge electrode is an excitation source
- a solid laser in which a solid laser medium such as YAG is a laser medium
- a lamp or a laser diode is an excitation source.
- the total reflection mirror 14 and the partial reflection mirror 15 constitute a resonator, and the laser medium 16a is excited by the excitation source 19a, whereby laser oscillation is performed, and laser light 18 is emitted from the partial reflection mirror. Is output.
- a Q switch 13a is inserted between the total reflection mirror 14 and the laser medium 16a
- a Q switch 13b is inserted between the partial reflection mirror 15 and the laser medium 16a.
- the pulsed laser beam is oscillated by opening and closing the Q switches 13a and 13b.
- the Q switches 13a and 13b are referred to as the first Q switch or the Q switch of the oscillation stage.
- the laser oscillator is assumed to have a high gain, for example, the gain per round trip of the resonator is 2.8.
- the diffraction efficiency per AZO element is 30% or more.
- a Q switch 13c is provided between the oscillation stage and the laser medium 16b, and a Q switch 13d is provided between the laser medium 16b and the laser medium 16c, and the laser medium 16c and the laser medium.
- a Q switch 13e is provided between 16d. While these Q switches 13c, 13d, and 16e are open (hereinafter, the Q switch is open is called gate-on, and the open period is called gate-on time g), the laser beam 18 enters the amplification stage and enters the laser. Amplify light. While the Q switches 13c, 13d, and 13e are closed (hereinafter, the Q switch is closed is referred to as gate-off, and the closed period is referred to as gate-off time). The configuration is such that it does not leak into the oscillation stage.
- the Q switches 13c, 13d, and 13e are referred to as the second Q switch or the Q switch of the amplification stage.
- Each of the first and second Q switches is controlled by the Q switch control unit 10 to adjust the timing of gate-on and gate-off.
- a Q switch using an AZO element will be described as an example of a high-speed Q switch that can withstand a high energy laser.
- the AZO element has a vibrator and, for example, quartz glass force.
- the vibrator By using the vibrator to vibrate quartz glass at a high frequency, ultrasonic waves are transmitted into the quartz glass.
- This ultrasonic wave forms a refractive index density in the quartz glass, and the quartz glass acts as a diffraction grating.
- the quartz glass acts as a diffraction grating.
- the incident light When acting as a diffraction grating, the incident light is diffracted and the optical path is bent. When it does not act as a diffraction grating, the incident light travels straight, and a switching operation is performed.
- Fig U harmonics, l la, l ib, l lc, l ld, 1 lei, respectively, output harmonic modulation signal Mrf to Q switches 13a, 13b, 13c, 13d, 13e consisting of A / O elements A harmonic modulation signal generator.
- the harmonic modulation signal generator 11 is controlled by the Q switch control unit 10.
- the diffracted light when the diffractive action is acting on the AZO element is absorbed by a damper or the like (not shown), and straight light without the diffractive action is used for laser output.
- a configuration in which diffracted light is used for laser oscillation and straight light is absorbed by a damper or the like may be used.
- the harmonic modulation signal Mrf is normally input from the harmonic modulation signal generator 11 to the vibrator of the AZO element, and when the vibrator vibrates, ultrasonic waves are generated in the AZO element.
- the transmitted AZO element acts as a diffraction grating, the laser light is diffracted, and the Q switch is in the gate-off state.
- Q switch control signals Cl and C2 are simultaneously output from the Q switch control unit 10 and input to the harmonic modulation signal generation units l la and l ib, respectively.
- the harmonic modulation signal generators l la and l ib stop outputting the harmonic modulation signals Mrf 1 and Mrf 2 when the Q switch control signals Cl and C 2 are input.
- the harmonic modulation signal input to the AZO element is stopped, the vibration of the vibrator of the AZO element stops, so the AZO element loses its function as a diffraction grating.
- the Q switch control unit 10 outputs the Q switch control signals Cl and C2 again after a predetermined gate on-time ⁇ g by the internal timer of the Q switch control unit 10, and the harmonic modulation signal generators l la and l ib Outputs the harmonic modulation signals Mrf 1 and Mrf2 again, and turns off the Q switches 13a and 13b.
- the basic operation is the same as that of the oscillation stage Q switch.
- the harmonic modulation signal generators l lc, l id, l ie stops the output of the harmonic modulation signals Mrf 3, Mrf4 and Mrf5, and the Q switches 13c, 13d and 13e are turned on.
- the Q switch control unit 10 outputs the Q switch control signals Cl and C2 again from the Q switch control unit 10 after the elapse of the specified gate on time by the internal timer of the Q switch control unit 10, and the harmonic modulation signal generator 11 outputs the harmonic modulation signal. Output again, and the Q switch enters the gate-off state.
- the gate on time ⁇ g may be the same value for the Q switch of the oscillation stage and the Q switch of the amplification stage, or it may not be set individually. It may be set appropriately according to the processing conditions.
- the gate-on timing of the oscillation stage Q switch and the Q-switch gate timing of the amplification stage if the conventional laser apparatus, the gate-on timing of the amplification stage Q switch In this invention, the gate-on timing of the Q switch of the amplification stage is advanced by several tens of ns from the oscillation stage.
- FIG. 2 shows temporal changes of the Q switch control signals C1 to C5 and the harmonic modulation signals Mrf1 to Mrf5 in the present invention.
- Fig. 2 when Q switch control signals C3, C4, and C5 are output from the Q switch control unit 10, harmonic modulation signals Mrf 3, Mrf4, and Mrf are output from the harmonic modulation signal generators l lc, l ld, and l ie. 5 is output.
- the Q switch control signals C3, C4, C5 are output and the Q switch control signals Cl, C2 are output from the Q switch control unit 10 after a predetermined time ⁇ 1, the harmonic modulation signal generators l la, l Harmonic modulation signals Mrfl and Mrf2 are output from ib.
- the timing at which the oscillation stage Q switch gate-on and the amplification stage Q switch gate on are shifted by ⁇ 1.
- the Q switch control unit 10 outputs the Q switch control signals C1 to C5 after the gate on time ⁇ g elapses after the gate is turned on as shown in FIG. Mrf 5 output is stopped and each Q switch is gated off.
- the rise of the laser gain is steep, so that the Q switch is opened and the resonator loss reaches the laser gain in a short time.
- the distance between Tl and ⁇ 3 is shortened.
- the force gain at which the growth of pulsed laser light starts from ⁇ 3 is high, the growth rate is fast and the build-up time is short, and b is also short. For this reason, the growth of the pulsed laser beam is completed by T4, that is, the output of the pulsed laser beam from the oscillation stage is completed.
- the oscillation stage force begins to output laser light. Just before T6, the fall of the diffraction loss of the Q switch in the amplification stage can be completed, and the loss in the Q switch of the amplification stage can be prevented.
- 1 should be set so that the time T5 when the fall of the Q-switch loss of the amplification stage is completed and the time point 6 at which the laser light starts to be output from the oscillation stage are simultaneous.
- T5 becomes slightly earlier than T6, for example, the timing shown in Figure 3 ⁇ 1 should be set as follows.
- the MOPA laser device is equipped with a high-gain high-energy Q-switch laser oscillator, so that the pulse laser light is generated after the Q switch of the oscillation stage starts to be turned on. Even if the time ⁇ ⁇ from the start of output to the output stage becomes shorter than the fall time ⁇ f of the Q switch of the amplification stage, the gate on timing of the Q switch of the oscillation stage is set to be higher than the gate on timing of the Q switch of the amplification stage. By controlling so as to delay for a predetermined time, it is possible to prevent loss of pulsed laser light at the Q switch of the amplification stage while maintaining the suppression of gain reduction due to the naturally amplified light generated at the amplification stage. Therefore, high-energy pulsed laser light can be obtained efficiently.
- the loss can be sufficiently ensured with one iS switch configured to dispose the first Q switch on both sides of the laser medium. If so, the first Q switch may be arranged only on one side of the laser medium.
- the second Q switch is arranged between the oscillation stage and the amplification stage and between each amplifier. However, when there are only three amplifiers as shown in Fig. 1, the gain of the amplifier is high. In this case, the influence of the naturally amplified light can be suppressed by arranging the second Q switch between at least one of the oscillation stage and the amplification stage or between the amplifiers.
- the first Q switch may be any one of 13a and 13b in FIG. 1.
- the second Q switch may have at least one of 13c, 13d, and 13e in FIG. Just place it.
- the configuration of the laser device when the first Q switch is 13a and the second Q switch is 13d is shown in FIG. In FIG. 4, the control of the first Q switch 13a and the second Q switch 13d is the same as the control described above.
- the number of amplifiers in the amplification stage is three.
- the number of amplifiers is not particularly limited, and the present embodiment can be applied to one or more amplifiers. If there are four or more amplifiers, add a second Q switch between the amplifiers as appropriate. Of course, there is no need to insert a second Q switch between all amplifiers. The second Q switch loss and the gain power of the amplifier can be inserted as many as necessary.
- the configuration of the laser device is as shown in Fig. 5.
- the second Q switch 13b prevents the naturally amplified light generated from the amplifier from reducing the gain of the laser oscillator, and the naturally amplified light that also generates the laser oscillator force reduces the gain of the amplifier. Has the effect of preventing.
- the control of the first Q switch 13a and the second Q switch 13c is the same as the control described above.
- the pulse laser waveform grows before the oscillation stage Q switch completes the gate-on, but the gate-on timing of the amplification stage Q switch is Since it is more advanced than the Q switch, the laser waveform is incident on the amplification stage after the Q switch of the amplification stage has completed gate-on. Therefore, loss of the pulsed laser beam at the Q switch in the amplification stage can be prevented. [0038] That is, depending on the condition setting and structure of the laser device, as a result, the time from when the Q switch of the oscillation stage starts gate-on until the force pulse laser beam starts to be output from the oscillator, the z force of the Q switch of the amplification stage It is very effective to apply the present invention when the fall time ⁇ f becomes shorter.
- the timing of gate-off will be described. Since the configuration of the apparatus is the same as in FIG. 1, description will be made using the reference numerals shown in FIG. 1 as appropriate.
- the naturally amplified light 17 incident on the laser medium 16 of the adjacent amplifier or oscillator is suppressed.
- the laser gain grows sufficiently until the gates of Q switches 13c, 13d, and 13e are turned on.
- the naturally amplified light 17 is incident on the laser medium 16 of the adjacent amplifier or oscillator, and the gain starts to decrease correspondingly.
- the energy of the laser beam is low, for example, about 50 W at the amplification final stage exit, and the decrease in gain is sufficiently slow in time. For this reason, the time change of the gain with respect to the naturally amplified light 17 can be made almost insensitive to the gate on / off operation of the Q switch by gate-off before the gain decrease becomes significant. It becomes.
- Figure 7 shows the time variation of the Q-stage loss of the oscillation stage, the laser gain, the pulse laser waveform output by the oscillation stage force, and the Q-switch loss of the amplification stage when the Q switch is operated at such timing.
- T5 and ⁇ 6 in Fig. 7 indicate the same time points as in Fig. 13, where ⁇ 7 is the time when the growth of the pulsed laser beam is completed, and ⁇ 8 is the time when the Q switch in the amplification stage is closed and the Q switch loss starts to rise.
- the Q switches 13c, 13d, and 13e in the amplification stage complete the gate-on at T5 immediately before T6 when the growth of the pulsed laser beam 18 becomes significant. Then, gate-off starts from T8 immediately after T7 when the growth of the pulsed laser beam 18 is completed.
- T5 and T6 it is desirable that the relationship between T5 and T6 is ideally matched. Considering variations such as fall time ⁇ 1 and pulse width of pulsed laser light, ⁇ 5 was set to be slightly faster than ⁇ 6. Similarly, in relation to ⁇ 7 and ⁇ 8, considering the variation, set the gate on time of the Q switch in the amplification stage appropriately so that ⁇ 8 is slightly later than ⁇ 7, for example, at the timing shown in Fig. 7. That's fine.
- the width ⁇ ⁇ ⁇ 6 to ⁇ 7 of the pulse laser beam is ⁇ w
- the time T2 to T8 from the start of gate-on of the Q switch of the amplification stage to the start of gate-off is ⁇ f + ⁇ + ⁇ w + ⁇ .
- a is set in the first embodiment, and j8 may be set appropriately in consideration of the degree of variation in ⁇ w and ⁇ f.
- the amplification stage or the amplification stage using the naturally amplified light further than the laser device described in the first embodiment It is possible to suppress a decrease in the gain of the oscillation stage, and it is possible to obtain a pulse laser beam that is more efficient and highly engineered.
- the gate on timing of the Q switch in the amplification stage is set higher than the gate on timing of the Q switch in the oscillation stage.
- the structure was advanced by one.
- the laser apparatus according to the present embodiment mechanically adjusts the gate-on timing of the Q switch in the amplification stage so as to be advanced by one earlier than the gate-on timing of the Q switch in the oscillation stage.
- FIG. 8 is a configuration diagram of the Q switch that also has a saddle element force used in the present embodiment, and corresponds to the Q switches 13a to 13e in FIG.
- the harmonic modulation signal output from the harmonic modulation signal generator 11 is input to the vibrator 21, and the vibrator 21 vibrates at a high frequency.
- an ultrasonic wave 23 is generated by the vibration of the vibrator 21, and is transmitted in a direction substantially orthogonal to the laser beam 18 as indicated by an arrow in FIG.
- the vibrator 21 and the quartz glass 20 are held by a position adjusting means 22 such as an optical stage having a function of translating in the same direction as the direction in which the ultrasonic wave 23 is transmitted. Thereby, the positions of the vibrator 21 and the quartz glass 20 can be freely changed in the direction in which the ultrasonic wave 23 is transmitted, that is, in the direction orthogonal to the laser beam 18. it can.
- the Q switch control signals C1 to C5 output from the Q switch control unit 10 are all output at the same timing.
- one signal C1 may be input to each harmonic modulation signal generator l la to l le.
- each harmonic modulation signal generator 11a ⁇ : Lie generates a harmonic modulation signal at the same timing.
- FIG. 9 is a view of the Q switch as viewed from the direction along the optical axis of the laser beam 18.
- Figure 9 (a) shows the oscillation stage Q switches 13a and 13b, and (b) shows the amplification stage Q switches 13c, 13d, and 13e.
- the ultrasonic wave 23 generated by the vibrator 21 is transmitted in the direction of the arrow in FIG. At this time, since the ultrasonic wave 23 has a finite speed, it takes time for the ultrasonic wave 23 to reach the laser beam 18 from the vibrator 21.
- Fig. 9 (a) if the distance from the vibrator 21 to the laser beam 18 is Lo and the sound velocity in the quartz glass 20 is V, it is necessary for the ultrasonic wave 23 to reach the laser beam 18 from the vibrator 21.
- the time variation of the loss of the amplification stage Q switch and the resonator loss of the oscillation stage when Lo and La are set is as shown in FIG.
- R is the beam diameter of the laser beam 18 in the Q switch.
- the fall time ⁇ f is expressed by RZV because the ultrasonic wave 23 crosses the beam diameter of the laser beam 18.
- ⁇ 1 may be set at a level of several tens of ns, but if it is set to 50 ns, for example, the speed of sound V in quartz glass is about 6 kmZs, so the difference between Lo and La should be set to 0.3 mm. Good. This value is a level that can be adjusted with high accuracy by a normal optical stage, and it is not necessary to use an expensive adjustment means.
- both the oscillation stage Q switch and the amplification stage Q switch are provided with adjusting means.
- the oscillation stage Q switch is amplified. Even if the adjustment means is provided only in one of the Q switches in the stage, the desired positional deviation can be realized, and the number of adjustment means can be reduced. Furthermore, if the machining conditions are always constant and the difference between Lo and La is always fixed, no adjustment means is provided and each Q switch is set so that the difference between Lo and La becomes the desired value. May be fixed to the laser device.
- the gate-on timing of the Q-switch of the amplification stage is set at a lower cost than the gate-on timing of the Q-switch of the oscillation stage at a low cost. It can be done.
- FIG. 11 is a block diagram showing a laser apparatus in the fourth embodiment for carrying out the present invention.
- the force in which the laser medium is arbitrary in the above-described embodiment
- a rod-type solid laser medium (hereinafter also simply referred to as a rod) is used as the laser medium. Since the basic configuration of the laser apparatus shown in FIG. 11 is the same as that of FIG. 1 of the first embodiment, the same components are denoted by the same reference numerals and detailed description thereof is omitted.
- 16a is an oscillation stage rod type solid state laser medium
- 16b, 16c and 16d are amplification stage rod type solid state laser media
- 19a to 19d are pumping rod type solid state laser media 16a to 16d, respectively.
- the pumping light 30a to 30d excites the laser medium.
- Representative examples of solid-state laser media include Nd: YAG, and examples of pumping light sources include lamps and laser diodes.
- 32 is a limiting aperture that shields unnecessary portions of the laser beam in order to prevent problems such as burning of the rod end.
- the most different from the configuration of the first embodiment is that only one Q switch of the amplification stage is provided!
- the Q switch of the amplification stage is configured such that only the Q switch 13e between the final amplifier of the amplification stage and the amplifier on the upper stage is removed, and the Q switches 13c and 13d in FIG. 1 are deleted.
- the rod operates as a thick lens with a positive curvature with respect to the laser beam.
- the force is such that only one force of the rod irradiates the excitation light.
- the excitation light is radiated symmetrically with the peripheral force of the rod.
- the beam profile of the laser beam 18 is as shown in FIG. 12 (a), where the beam diameter is expanded in the rod and the beam diameter is reduced outside the rod.
- the laser beam 18 is emitted from the oscillation stage and has high condensing characteristics.As shown in Fig. 12 (a), the beam diameter in each amplifier is substantially equal, and the beam diameter between the amplifiers is also the same. Each is in an approximately equal state.
- the beam profile of the naturally amplified light 17 is as shown in FIG. Since the natural amplified light 17 is not generated by resonance, the condensing characteristic is very bad.
- the M2 of the laser light 18 is about 12 (mm 'mrad), but the natural amplified light is 200 (mm mrad) or more (measurement limit or more).
- M2 is an index representing the light collection characteristic, and is disclosed in detail in SPIE Vo 1.1414 “Laser Beam Diagnostics” (1991).
- the naturally amplified light 17 is less likely to enter the amplifier with a higher ratio of being blocked by the aperture 32b.
- the natural amplification light 17 has a higher light collection characteristic due to the lens effect of each amplifier rod.
- M2 is about 50 (mm * mrad). It improves. Therefore, in the final amplification stage, the naturally amplified light 17 shielded by the aperture decreases, and the naturally amplified light 17 that enters the amplifier increases.
- the Q switch 13e may be provided only between the final amplifier in the amplification stage and the amplifier on the upper stage side.
- the amplifier gain is high!
- at least one second Q switch has only to be arranged in the amplification stage.
- this embodiment It is also effective to place one second Q switch in the amplification stage as in the configuration.
- the effect of the laser device according to the present invention is particularly remarkable when used in a laser device having a MOPA configuration equipped with a high gain and high energy laser oscillator.
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- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
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- Optics & Photonics (AREA)
- Lasers (AREA)
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/JP2005/006911 WO2006114842A1 (ja) | 2005-04-08 | 2005-04-08 | レーザ装置 |
JP2006520512A JP4640336B2 (ja) | 2005-04-08 | 2005-04-08 | レーザ装置 |
DE112005001423.1T DE112005001423B4 (de) | 2005-04-08 | 2005-04-08 | Lasersystem |
US11/632,164 US7564879B2 (en) | 2005-04-08 | 2005-04-08 | Laser system |
TW094117008A TWI269504B (en) | 2005-04-08 | 2005-05-25 | Laser apparatus |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/JP2005/006911 WO2006114842A1 (ja) | 2005-04-08 | 2005-04-08 | レーザ装置 |
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WO2006114842A1 true WO2006114842A1 (ja) | 2006-11-02 |
Family
ID=37214481
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PCT/JP2005/006911 WO2006114842A1 (ja) | 2005-04-08 | 2005-04-08 | レーザ装置 |
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US (1) | US7564879B2 (ja) |
JP (1) | JP4640336B2 (ja) |
DE (1) | DE112005001423B4 (ja) |
TW (1) | TWI269504B (ja) |
WO (1) | WO2006114842A1 (ja) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007287946A (ja) * | 2006-04-18 | 2007-11-01 | Mitsubishi Electric Corp | Qスイッチレーザ装置及びqスイッチレーザ装置の調整方法 |
JP2014103287A (ja) * | 2012-11-21 | 2014-06-05 | Shimadzu Corp | 固体レーザ装置 |
WO2018092281A1 (ja) * | 2016-11-18 | 2018-05-24 | ギガフォトン株式会社 | レーザ装置および極端紫外光生成装置 |
JP2018186154A (ja) * | 2017-04-25 | 2018-11-22 | 浜松ホトニクス株式会社 | 固体レーザ装置 |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8462425B2 (en) * | 2010-10-18 | 2013-06-11 | Cymer, Inc. | Oscillator-amplifier drive laser with seed protection for an EUV light source |
JP2012199425A (ja) | 2011-03-22 | 2012-10-18 | Gigaphoton Inc | マスタオシレータ、レーザシステム、およびレーザ生成方法 |
JP5844535B2 (ja) | 2011-03-28 | 2016-01-20 | ギガフォトン株式会社 | レーザシステムおよびレーザ生成方法 |
JP5844536B2 (ja) | 2011-03-28 | 2016-01-20 | ギガフォトン株式会社 | レーザシステムおよびレーザ生成方法 |
US9570882B2 (en) * | 2013-03-27 | 2017-02-14 | Coherent Lasersystems Gmbh & Co. Kg | MOPA with externally triggered passively Q-switched laser |
WO2016141290A1 (en) * | 2015-03-05 | 2016-09-09 | Nufern | Method and apparatus for providing amplified radiation |
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JPH055912A (ja) * | 1991-06-27 | 1993-01-14 | Nippon Telegr & Teleph Corp <Ntt> | 多段光増幅装置 |
US5400350A (en) * | 1994-03-31 | 1995-03-21 | Imra America, Inc. | Method and apparatus for generating high energy ultrashort pulses |
JP2001308427A (ja) * | 2000-04-26 | 2001-11-02 | Nippon Steel Corp | 高出力パルスレーザ装置 |
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US6078606A (en) * | 1975-03-17 | 2000-06-20 | Lockheed Martin Corporation | Multi-color, multi-pulse laser |
US5181135A (en) * | 1990-12-21 | 1993-01-19 | Kaman Aerospace Corporation | Optical underwater communications systems employing tunable and fixed frequency laser transmitters |
US5247388A (en) * | 1992-05-27 | 1993-09-21 | Dynetics, Inc. | Continuously variable delay lines |
US5721749A (en) * | 1996-01-30 | 1998-02-24 | Trw Inc. | Laser pulse profile control by modulating relaxation oscillations |
US6181463B1 (en) | 1997-03-21 | 2001-01-30 | Imra America, Inc. | Quasi-phase-matched parametric chirped pulse amplification systems |
US5987042A (en) * | 1997-10-31 | 1999-11-16 | General Electric Company | Method and apparatus for shaping a laser pulse |
US6738396B2 (en) * | 2001-07-24 | 2004-05-18 | Gsi Lumonics Ltd. | Laser based material processing methods and scalable architecture for material processing |
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2005
- 2005-04-08 WO PCT/JP2005/006911 patent/WO2006114842A1/ja not_active Application Discontinuation
- 2005-04-08 US US11/632,164 patent/US7564879B2/en not_active Expired - Fee Related
- 2005-04-08 DE DE112005001423.1T patent/DE112005001423B4/de not_active Expired - Fee Related
- 2005-04-08 JP JP2006520512A patent/JP4640336B2/ja not_active Expired - Fee Related
- 2005-05-25 TW TW094117008A patent/TWI269504B/zh not_active IP Right Cessation
Patent Citations (3)
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JPH055912A (ja) * | 1991-06-27 | 1993-01-14 | Nippon Telegr & Teleph Corp <Ntt> | 多段光増幅装置 |
US5400350A (en) * | 1994-03-31 | 1995-03-21 | Imra America, Inc. | Method and apparatus for generating high energy ultrashort pulses |
JP2001308427A (ja) * | 2000-04-26 | 2001-11-02 | Nippon Steel Corp | 高出力パルスレーザ装置 |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007287946A (ja) * | 2006-04-18 | 2007-11-01 | Mitsubishi Electric Corp | Qスイッチレーザ装置及びqスイッチレーザ装置の調整方法 |
JP2014103287A (ja) * | 2012-11-21 | 2014-06-05 | Shimadzu Corp | 固体レーザ装置 |
WO2018092281A1 (ja) * | 2016-11-18 | 2018-05-24 | ギガフォトン株式会社 | レーザ装置および極端紫外光生成装置 |
US10481422B2 (en) | 2016-11-18 | 2019-11-19 | Gigaphoton Inc. | Laser device and extreme ultraviolet light generation device |
JP2018186154A (ja) * | 2017-04-25 | 2018-11-22 | 浜松ホトニクス株式会社 | 固体レーザ装置 |
JP6998127B2 (ja) | 2017-04-25 | 2022-01-18 | 浜松ホトニクス株式会社 | 固体レーザ装置 |
Also Published As
Publication number | Publication date |
---|---|
JPWO2006114842A1 (ja) | 2008-12-11 |
US7564879B2 (en) | 2009-07-21 |
DE112005001423B4 (de) | 2015-05-28 |
DE112005001423T5 (de) | 2008-02-21 |
US20070263677A1 (en) | 2007-11-15 |
TWI269504B (en) | 2006-12-21 |
JP4640336B2 (ja) | 2011-03-02 |
TW200637088A (en) | 2006-10-16 |
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