JP6571943B2 - Laser light source device and laser pulse light generation method - Google Patents

Description

  The present invention relates to a laser light source device and a laser pulse light generation method used for various types of laser processing.

  In recent years, laser light has been used for various processes. Laser light having a wavelength in the vicinity of 532 nm to 1064 nm has high energy intensity, and is suitably used for various processing such as cutting or welding of metal or glass. In addition, laser light in the deep ultraviolet region with a wavelength of 200 nm to 350 nm is used for processing electronic materials and composite materials.

  A laser light source device that outputs laser light having a shorter wavelength than the near infrared region includes a seed light source that outputs laser light having a wavelength in the near infrared region, an optical amplifier that amplifies the laser light output from the seed light source, A nonlinear optical element that converts the wavelength of the laser light amplified by the optical amplifier into a target wavelength is provided.

  Various seed light sources are selected and various kinds of light sources are selected so that a laser pulse light having a pulse width of several nanoseconds or less, preferably several hundred picoseconds or less and a repetition frequency of several hundred megahertz or less can be obtained. An optical amplifier or the like is used.

  Conventionally, a mode-locked laser with a repetition frequency of several tens of megahertz is used as such a seed light source, and a pulse light of several kilohertz is obtained by dividing the pulse light output from the seed light source. there were.

  However, since the oscillation frequency of the mode-locked laser fluctuates due to environmental factors such as temperature and vibration, and it is difficult to control the value appropriately, the oscillation frequency of the laser pulse light detected using a light receiving element etc. Therefore, there is a problem that the circuit configuration for this is complicated, and that the saturable absorber that is a component of the mode-locked laser is easily deteriorated and long-term stable driving is difficult. It was.

  Therefore, it is conceivable to use a semiconductor laser capable of controlling the oscillation frequency of pulsed light as a seed light source. The pulse energy of near-infrared pulsed light output from such a semiconductor laser is from several picojoules to several hundreds of picojoules. In order to finally obtain pulsed light having a pulse energy of a few tens of microjoules to several tens of millijoules, which is very small as a picojoule, it is necessary to amplify much more than when a conventional seed light source is used.

  As optical amplifiers therefor, fiber amplifiers such as erbium-doped fiber amplifiers and ytterbium-doped fiber amplifiers, Nd: YAG with neodymium added to yttrium aluminum garnet, and Nd: YVO4 with neodymium added to yttrium vanadate. A solid-state amplifier such as is preferably used.

  Patent Documents 1 and 2 disclose an optical amplifier in which such a fiber amplifier and a solid-state amplifier are combined. As shown in Patent Documents 1 and 2, both fiber amplifiers and solid-state amplifiers are used for excitation in order to amplify light having the same wavelength as the laser light to be amplified by the pumping action in the laser active region. It is necessary to provide a light source. Usually, a semiconductor laser is used as such a light source for excitation.

JP 2011-192831 A WO2008 / 014331

  When processing using the pulsed light output from the laser light source device described above, if pulse light with a low repetition frequency of 100 kilohertz or less, particularly several tens of kilohertz or less is output, Before the pulsed light is output, the laser active region of the solid-state amplifier is excessively excited by the excitation laser light source, resulting in an excessive inversion distribution state, and the solid-state amplifier may be damaged when the pulsed light is amplified. there were.

  As a solution to this problem, an optical lens that expands the beam diameter is placed in the optical path of the optical pulse to reduce the energy density of the optical pulse incident on the solid-state amplifier, thereby avoiding damage to the solid-state amplifier even at a low repetition rate. It is possible to do.

  However, when such a configuration is adopted, the peak power of the optical pulse is reduced and the energy density is reduced in a region where the repetition frequency is high, so that the intensity that can be converted by the wavelength conversion element cannot be sufficiently amplified by the solid-state amplifier, There was a problem that a laser light source device having versatility capable of output at different repetition frequencies could not be configured.

  In view of the above-described problems, an object of the present invention is to provide a general-purpose laser light source device and a laser pulse light generation method capable of outputting at a wide range of repetition frequencies without causing damage to the solid-state amplifier.

  In order to achieve the above object, the first characteristic configuration of the laser light source device according to the present invention is, as described in claim 1 of the claims, a first light source that outputs pulsed light by a gain switching method, A fiber amplifier that amplifies the pulsed light output from the first light source; a solid-state amplifier that amplifies the pulsed light output from the fiber amplifier; and a nonlinear that outputs the pulsed light output from the solid-state amplifier after wavelength conversion. An optical element, and a second light source that outputs laser light that can be combined with pulsed light that is arranged upstream of the solid-state amplifier and that is output from the first light source; A controller that variably controls the power of the laser light output from the second light source and input to the solid-state amplifier in accordance with the repetition frequency of the pulsed light output from the first light source. It lies in the fact that.

  When the laser light output from the second light source is incident on the solid-state amplifier, the excitation energy accumulated in the laser active region of the solid-state amplifier is consumed according to the power of the laser light. Since the excitation state of the laser active region of the solid-state amplifier varies depending on the repetition frequency of the pulsed light output from the first light source, the power of the laser light output from the second light source by the control unit is a value corresponding to the repetition frequency. Thus, the amplification factor of the pulsed light is adjusted so that the wavelength conversion efficiency of the optical pulse by the subsequent wavelength conversion element is not lowered and the solid-state amplifier is not damaged. The “repetitive frequency of pulsed light” used in the present invention refers to the reciprocal of the time from the rise of pulsed light to the rise of the next pulsed light, including the concept that a single pulse is repeated at an arbitrary time interval. It is.

  In the second feature configuration, as described in claim 2, in addition to the first feature configuration described above, the control unit is configured to reduce the repetition frequency of the pulsed light output from the first light source. In order to increase the repetition frequency of the pulsed light output from the first light source, the power of the laser light output from the second light source and input to the solid-state amplifier is increased stepwise or continuously. Along with this, the power of the laser beam output from the second light source and input to the solid-state amplifier is controlled to be lowered stepwise or continuously.

  The excitation state of the laser active region of the solid-state amplifier at the time of amplification of the optical pulse becomes excessive as the repetition frequency of the pulsed light output from the first light source decreases. This is because the time to be excited before the amplification of the light pulse becomes longer. Therefore, by adjusting the power of the laser light output from the second light source stepwise or continuously according to the repetition frequency, wavelength conversion of the optical pulse by the subsequent wavelength conversion element regardless of the repetition frequency. The amplification factor of the pulsed light is adjusted so that the efficiency is not lowered and the solid-state amplifier is not damaged.

  In the third feature configuration, as described in claim 3, in addition to the first or second feature configuration described above, the control unit has a repetition frequency of the pulsed light output from the first light source. The power of the laser beam output from the second light source and input to the solid-state amplifier is variably controlled when the frequency is equal to or lower than a predetermined frequency.

  Since the excitation state of the laser active region of the solid-state amplifier becomes excessive in the region where the repetition frequency of the pulsed light output from the first light source is low, the repetition frequency is equal to or lower than a predetermined frequency at which such an excessive excitation state is obtained. Furthermore, if the power of the laser beam output from the second light source is adjusted, the solid-state amplifier can be prevented from being damaged.

  In the fourth feature configuration, in addition to any one of the first to third feature configurations described above, the control unit outputs at least pulsed light from the first light source. The laser light is controlled to be output from the second light source in a period different from the period.

  It is necessary to avoid excessive excitation of the laser active region of the solid-state amplifier during a period different from the output period of the pulsed light from the first light source. For this purpose, it is only necessary to control so that the laser light is output from the second light source at least during a period different from the output period of the pulsed light from the first light source.

  In the fifth feature configuration, as described in claim 5, in addition to any of the first to fourth feature configurations described above, the control unit is configured to control the pulse light output from the first light source. Regardless of the repetition frequency, the power of the laser beam output from the second light source and input to the solid-state amplifier is pointed so that the average power of the light output from the solid-state amplifier is substantially constant.

  Laser output from the second light source so that the average power of the light output from the solid-state amplifier, that is, the combined light of the pulsed light output from the first light source and the laser light output from the second light source is substantially constant. By adjusting the power of the light, the solid-state amplifier can be stably brought into an appropriate excitation state when amplifying the pulsed light regardless of the value of the repetition frequency of the pulsed light output from the first light source. Will be maintained. For example, the average power of the output light from the solid-state amplifier is adjusted so that the solid-state amplifier is in an appropriate excitation state at a predetermined repetition frequency, and the adjustment value is maintained when the repetition frequency changes. The power of the laser beam output from the second light source may be adjusted.

  In the sixth feature configuration, as described in claim 6, in addition to any of the first to fifth feature configurations described above, the control unit is configured to control the pulse light output from the first light source. The control unit determines the correspondence between the repetition frequency and the power of the laser beam output from the second light source and input to the solid state amplifier from the repetition frequency of the pulsed light output from the first light source and the second light source. The power of the laser light output from the second light source that controls the power of the laser light output from the second light source based on the correspondence is defined in advance. The point is to control.

  Since the control unit can grasp the power of the laser light to be output from the second light source corresponding to the repetition frequency of the pulsed light output from the first light source based on the correspondence relationship defined in advance. A complicated calculation process for obtaining the target power of the laser beam output from the second light source is not necessary. For example, the correspondence can be defined by a function that determines the power of the laser light output from the second light source with the repetition frequency of the pulsed light output from the first light source as a variable. The power of the laser light output from the second light source can be defined by a relation table that can be obtained by referring to a memory that uses the repetition frequency of the output pulsed light as a reference address.

  In the seventh feature configuration, as described in claim 7, in addition to any of the first to sixth feature configurations described above, the oscillation wavelength of the second light source is output from the first light source. The amplification band of the solid-state amplifier capable of amplifying the pulsed light to be amplified is set.

  By setting the oscillation wavelength of the second light source in the amplification band of the solid-state amplifier, the excitation energy accumulated excessively in the solid-state amplifier is consumed for amplification of the laser light output from the second light source. If the power of the laser light output from the second light source is inherently low, even if it is amplified by the solid-state amplifier, the wavelength is not converted as light having a large peak power by the nonlinear optical element.

  In the eighth feature configuration, as described in claim 8, in addition to any of the first to sixth feature configurations described above, the oscillation wavelength of the second light source may be an amplification band of the solid-state amplifier. Of these, the amplification band other than the amplification band capable of amplifying the pulsed light output from the first light source is set.

  If there are multiple amplification bands of the solid-state amplifier and the oscillation wavelength of the second light source is set to an amplification band other than the amplification band that can amplify the pulsed light output from the first light source, the solid-state amplifier will accumulate excessively. The excitation energy is consumed for amplification of the laser light output from the second light source. Even if the laser light output from the second light source is amplified by the solid-state amplifier and incident on the nonlinear optical element, the laser light has a wavelength different from the band that can be converted by the nonlinear optical element. No light is output.

  In the ninth feature configuration, in addition to any one of the first to eighth feature configurations described above, the control unit may include pulse light output from the nonlinear optical element. The repetition frequency of the pulsed light output from the first light source and the second light source so that the laser fluence of the pulsed light is constant regardless of the relative moving speed with the processing object processed by the pulsed light. The power of the laser beam output from the laser and input to the solid-state amplifier is variably controlled.

  In order to maintain the laser fluence at a predetermined value while the repetition frequency of the pulsed light is constant, the relative moving speed of the pulsed light and the object to be processed by the pulsed light needs to be maintained constant. is there. Therefore, if the machining cannot be performed until the relative moving speed with respect to the machining target becomes constant, the machining efficiency is lowered. In addition, the processing site to be processed is not always linear but may be curved, and it is extremely difficult to keep the relative moving speed constant at such a curved site. In such a case, it is necessary to maintain the laser fluence constant by adjusting the repetition frequency of the pulsed light according to the relative moving speed with the object to be processed. There is a possibility that the excitation state of the amplifier fluctuates and cannot be processed properly. However, by variably controlling the repetition frequency of the pulsed light and the power of the laser light output from the second light source, the wavelength conversion efficiency of the optical pulse by the subsequent wavelength conversion element is reduced regardless of the repetition frequency of the pulsed light. Thus, the amplification factor of the pulsed light is adjusted so that the solid-state amplifier is not damaged, and the object to be processed can be processed with high processing efficiency.

  In the tenth feature configuration, as described in claim 10, in addition to any of the first to ninth feature configurations described above, the fiber amplifier is disposed between the fiber amplifier and the solid-state amplifier. Further comprising an optical switch element that allows or blocks the propagation of light from the first amplifier to the solid-state amplifier, and the control unit has the first frequency when the repetition frequency of the pulsed light output from the first light source is higher than a predetermined frequency. The optical switching element is controlled to allow light propagation during an output period of pulsed light from the light source and prevent light propagation during a period different from the output period of pulsed light from the first light source. There is in point.

  When the repetition frequency of the pulsed light is higher than a predetermined frequency, the excitation energy accumulated in the laser active region of the solid-state amplifier is relatively reduced, and when the excitation energy is consumed by the laser light output from the second light source, There is a possibility that the excitation energy used for the amplification of the pulse is lowered and the amplification efficiency is lowered. Even in such a case, the optical switch element that allows or blocks the propagation of light from the fiber amplifier to the solid-state amplifier is controlled to allow the light to propagate during the output period of the pulsed light from the first light source. If the propagation of light is prevented during a period different from the output period of the pulsed light from the light, the excitation energy can be used efficiently for amplification of the light pulse.

  According to the first characteristic configuration of the laser pulse light generation method of the present invention, the pulse light output from the first light source by the gain switching method is sequentially amplified by the fiber amplifier and the solid-state amplifier, and amplified. A laser pulse light generation method for outputting a pulsed light beam after wavelength conversion by a nonlinear optical element, the second pulse light being arranged upstream of the solid-state amplifier and capable of being combined with the pulsed light output from the first light source. The power of the laser light output from the light source and input to the solid-state amplifier is variably controlled according to the repetition frequency of the pulsed light output from the first light source.

  As described in claim 12, the second characteristic configuration includes stepwise or in addition to the first characteristic configuration described above, as the repetition frequency of the pulsed light output from the first light source decreases. The power of the laser beam that is continuously output from the second light source and input to the solid-state amplifier is controlled so as to increase, and as the repetition frequency of the pulsed light output from the first light source increases, the first light source The power of laser light output from two light sources and input to the solid-state amplifier is controlled so as to decrease stepwise or continuously.

  In the third feature configuration, in addition to the first or second feature configuration described above, the solid state is the same regardless of the repetition frequency of the pulsed light output from the first light source. The power of the laser beam output from the second light source and input to the solid-state amplifier is adjusted so that the average power of the light output from the amplifier becomes substantially constant.

  In addition to any one of the first to third feature configurations described above, the fourth feature configuration is processed by the pulsed light output from the nonlinear optical element and the pulsed light. The repetition rate of the pulsed light output from the first light source and the second light source are output to the solid-state amplifier so that the laser fluence is constant regardless of the relative movement speed with respect to the processed object. The power of the laser beam is variably controlled.

  As described above, according to the present invention, it is possible to provide a general-purpose laser light source device and a laser pulse light generation method capable of outputting at a wide range of repetition frequencies without causing damage to the solid-state amplifier. It was.

Block diagram of a laser light source device according to the present invention (A) is an explanatory diagram of the state of excitation energy stored in the solid-state amplifier in a region where the repetition frequency is relatively high, and (b) is an explanatory diagram of the state of excitation energy stored in the solid-state amplifier in a region where the repetition frequency is relatively low. FIG. 4C is an explanatory diagram of the state of excitation energy accumulated in the solid-state amplifier when laser light is input from the second light source in a region where the repetition frequency is relatively low. (A) is explanatory drawing of the power of the laser beam output from the 2nd light source variably adjusted according to the repetition frequency of pulsed light, (b) is output from the 2nd light source according to the repetition frequency of pulsed light. An explanatory diagram of an example in which the power of the laser beam is adjusted, (c) is an explanatory diagram of an example in which the power of the laser beam output from the second light source is adjusted stepwise according to the repetition frequency of the pulsed light, (d) ) Is an explanatory diagram of a mode in which the second light source is driven only when the pulsed light is off. (A) is explanatory drawing of the processing apparatus with which the laser light source device was integrated, (b), (c) is explanatory drawing of a laser fluence. (A) is explanatory drawing of the frequency characteristic and time-axis characteristic of the narrow band pulsed light oscillated from a 1st light source, (b), (c) is the pulsed light broadened by the self phase modulation and Raman scattering of the fiber amplifier. Of frequency characteristics and time axis characteristics (A) is an explanatory diagram of pulsed light periodically oscillated from the first light source, (b) is an explanatory diagram of pulsed light on which ASE noise is superimposed by a subsequent fiber amplifier, and (c) is a first light source in the time domain. FIG. 4D is an explanatory diagram of the pulsed light after passing through the optical switching element in synchronization with the oscillation period of FIG. 2, (d) is passing through the optical switching element in synchronization with the oscillation period of the first light source in the time domain and amplified by the solid-state amplifier Of the pulsed light (A), (b) is explanatory drawing of the relationship between the amplification zone | band of a solid-state amplifier, and the oscillation wavelength of a 2nd light source. The block block diagram which shows another embodiment of the laser light source apparatus by this invention

Embodiments of a laser light source device and a laser pulse light generation method according to the present invention will be described below.
FIG. 1 shows an exemplary configuration of a laser light source device 1 according to the present invention. The laser light source device 1 includes a light source unit 1A, a fiber amplification unit 1B, a solid amplification unit 1C, and a wavelength conversion unit 1D arranged along the optical axis L, and further includes a control unit 100 that controls the light source unit 1A and the like. It is prepared for.

  The light source unit 1A includes a seed light source 10 serving as a first light source of the present invention, a driver D1 for seed light source, an optical isolator ISL1 for seed light source, a laser light source 11 serving as a second light source of the present invention, and a laser. A light source driver D11, a laser light source optical isolator ISL11, and a photodiode PD for monitoring the power of output light from the laser light source 11 are provided.

  The fiber amplifying unit 1B includes two-stage fiber amplifiers 20 and 30 each having excitation light sources 21 and 31 and multiplexers 22 and 32 each composed of a laser diode, optical isolators ISL2 and ISL3, and an optical switch element. 40 etc.

  A multiplexer 23 is provided on the input side of the fiber amplifier 20 in the previous stage so that the laser light output from the laser light source 11 and the laser pulse light output from the seed light source 10 can be combined. A demultiplexer 24 for guiding the output light of the fiber amplifier 20 to the photodiode PD is provided.

  The solid-state amplifier 1C includes a solid-state amplifier 50, an excitation light source 51, reflection mirrors M1, M2, and M3, a lens L1, a collimator CL2, and the like. The wavelength conversion unit 1D includes a first wavelength conversion unit 1E and a second wavelength conversion unit 1F, and includes nonlinear optical elements 60 and 70, respectively.

  Laser pulse light with a wavelength of 1064 nm output from the seed light source 10 (hereinafter also simply referred to as “pulse light”) is amplified by the two-stage fiber amplifiers 20 and 30 and further amplified to a desired level by the one-stage solid-state amplifier 50. Is done. The pulsed light amplified by the solid-state amplifier 50 is wavelength-converted to a wavelength of 532 nm by the nonlinear optical element 60 and further wavelength-converted to a wavelength of 266 nm by the nonlinear optical element 70 and output.

  The number of fiber amplifiers and solid-state amplifiers is not particularly limited, and may be set as appropriate in order to obtain a desired amplification factor for pulsed light. For example, three fiber amplifiers may be cascaded, and two solid state amplifiers may be cascaded in the subsequent stage.

  A distributed feedback laser diode (hereinafter referred to as “DFB laser”) that outputs a single longitudinal mode laser beam is used as the seed light source 10, and is controlled by a control signal output from the control unit 100 to which the gain switching method is applied. From the DFB laser, pulse light having a desired pulse width of several nanoseconds or less, preferably several hundred picoseconds or less is output at a desired frequency of one shot or several megahertz or less.

  As the laser light source 11, a general-purpose semiconductor laser using a Fabry-Perot resonator capable of outputting CW light or pulsed light is used.

  Pulse light having a pulse energy of several picojoules to several hundred picojoules output from the seed light source 10 is finally pulsed by the fiber amplifiers 20 and 30 and the solid-state amplifier 50 with a pulse energy of several tens of microjoules to several tens of millijoules. After being amplified to light, it is converted into deep ultraviolet rays having a wavelength of 266 nm by being input to the two-stage nonlinear optical elements 60 and 70.

  The pulsed light output from the seed light source 10 is amplified by the first-stage fiber amplifier 20 via the optical isolator ISL1. As the fiber amplifiers 20 and 30, rare earth-doped optical fibers such as ytterbium (Yb) -doped fiber amplifiers pumped by a pumping light source 21 having a predetermined wavelength (for example, 975 nm) are used. Since the lifetime of the inversion distribution of the fiber amplifier 20 is in the order of milliseconds, the energy excited by the excitation light source 21 is efficiently transferred to pulsed light having a frequency of 1 kilohertz or more.

  The pulse light amplified by about 30 dB by the first-stage fiber amplifier 20 is input to the subsequent-stage fiber amplifier 30 via the optical isolator ISL2 and amplified by about 25 dB. The pulsed light amplified by the subsequent fiber amplifier 30 is beam-shaped by the collimator CL1, passes through the optical isolators ISL3 and ISL4, is guided to the solid-state amplifier 50, and is amplified by about 25 dB.

  A pair of reflecting mirrors M1 and M2 are disposed between the collimator CL1 and the solid-state amplifier 50, and an optical isolator ISL4 that guides the pulsed light amplified by the solid-state amplifier 50 to the nonlinear optical element 60 between the reflecting mirrors M1 and M2. Is arranged.

  The above-described optical isolators ISL1 to ISL4 are all polarization-dependent types that block return light by rotating the polarization plane in the opposite direction to the forward direction of the light propagation direction using the magneto-optic effect. Each optical element, which is an optical isolator and is arranged upstream along the optical axis, is provided to avoid thermal destruction by high-power return light.

  As the solid-state amplifier 50, a solid-state laser medium such as Nd: YVO4 crystal or Nd: YAG crystal is preferably used. The solid-state laser medium is configured to be excited by the excitation light output from the excitation light source 51 including a laser diode having an emission wavelength of 808 nm or 888 nm and beam-formed by the collimator CL2.

  The pulsed light that has passed through the optical isolator ISL3 is incident on the solid-state amplifier 50 via the reflection mirrors M1 and M2 and amplified, and then reflected by the reflection mirror M3 and re-enters the solid-state amplifier 50 to be amplified again. The That is, it is configured to be amplified on the forward path and the return path of the solid-state amplifier 50, respectively. The lens L1 is for beam shaping.

  The pulsed light amplified by the solid-state amplifier 50 is reflected by the reflection mirror M2 and the optical isolator ISL4, is incident on the nonlinear optical elements 60 and 70 of the wavelength conversion unit 1D, is converted to a desired wavelength, and is output.

The first wavelength conversion unit 1E incorporates an LBO crystal (LiB ₃ O ₅ ) that is a nonlinear optical element 60, and the second wavelength conversion unit 1F incorporates a CLBO crystal (CsLiB ₆ O ₁₀ ) that is a nonlinear optical element 70. It is. The pulse light having a wavelength of 1064 nm output from the seed light source 10 is wavelength-converted to a wavelength of 532 nm by the nonlinear optical element 60, and further wavelength-converted to a wavelength of 266 nm by the nonlinear optical element 70.

  The reflection mirrors M4 and M8 function as a filter for separating pulsed light with a wavelength of 1064 nm output from the nonlinear optical element 60, and the reflection mirror M6 is for separating pulsed light with a wavelength of 532 nm output from the nonlinear optical element 70. Each of the separated pulse lights is attenuated by an optical damper.

The second wavelength conversion unit 1F is provided with a stage 71 that is a scanning mechanism that moves a CLBO crystal (CsLiB ₆ O ₁₀ ) in a plane orthogonal to the optical axis. For lowering the ultraviolet When is irradiated to the same position long CLBO crystal (CsLiB ₆ O ₁₀₎ in the degradation and the wavelength converted output of the intensity distribution generated optical damage, CLBO crystal in a predetermined time (CsLiB ₆ O ₁₀₎ This is to shift the irradiation position of the pulsed light to

  The control unit 100 includes a circuit block including an FPGA (Field Programmable Gate Array), peripheral circuits, and the like, and a plurality of logic elements are driven based on a program stored in advance in a memory in the FPGA. Each block constituting 1 is controlled sequentially, for example. In addition to the FPGA, the control unit 100 may be configured with a microcomputer, a peripheral circuit such as a memory and an IO, or may be configured with a programmable logic controller (PLC) or the like.

  Specifically, the control unit 100 outputs a trigger signal having a predetermined pulse width to the driver D1 of the DFB laser that is the seed light source 10 in order to cause the seed light source 10 to emit light using the gain switching method. When a pulse current corresponding to the trigger signal is applied from the drive circuit to the DFB laser, relaxation oscillation occurs, and only the first wave having the highest emission intensity immediately after the start of light emission due to relaxation oscillation consists of the second and subsequent sub-pulses. A pulsed laser beam not included is output. The gain switching method refers to a method of generating pulsed light having a short pulse width and high peak power using such relaxation oscillation.

  2A and 2B show the repetition frequency of the pulsed light incident on the solid-state amplifier 50 when the power of the pumping light output from the pumping light source 51 is constant, and the solid-state amplifier by the pumping light source 51. The relationship of the excitation energy (the degree of inversion distribution state) accumulated in 50 is schematically shown.

  When the pulsed light is incident, the excitation energy that has been accumulated in the solid-state amplifier 50 until then is spent for amplification of the pulsed light and then released, and then the excitation energy is accumulated in preparation for the next pulsed light.

  As shown in FIG. 2A, when the repetition frequency of the pulsed light is high, the interval time between the pulsed light and the pulsed light is shortened, so that the excitation energy accumulated during that time does not increase so much, but as shown in FIG. In addition, when the repetition frequency is lowered, the interval time between the pulsed light and the pulsed light is gradually increased, so that the excitation energy accumulated during that time gradually increases. 2A and 2B show only the excitation energy used for amplification of the pulsed light among the excitation energies accumulated in the solid-state amplifier 50 and are actually accumulated in the solid-state amplifier 50. It does not mean that all of the excitation energy is used for amplification of pulsed light.

  When the repetition frequency is 100 kilohertz or less, particularly 50 kilohertz or less, the excitation energy accumulated in the solid-state amplifier 50 becomes excessive, and the solid-state amplifier 50 may be damaged.

  Therefore, it is also conceivable to adjust the power of the pumping light output from the pumping laser light source 51 of the solid-state amplifier 50 so as not to accumulate excessive energy.

  However, if the intensity of the excitation light is variably adjusted, the beam center of the pulsed light may be shifted due to the thermal lens effect exhibited by the solid-state laser medium. Since it is difficult to accurately adjust the optical axis of the excitation light incident on the solid-state laser medium, the heat distribution state of the solid-state laser medium fluctuates when the intensity of the excitation light fluctuates and is affected by the thermal lens effect accordingly. Because.

  As shown in FIG. 2C, in such a case, when the control unit 100 controls the laser light source D11 provided in the light source unit 1A to output laser light, A part of the accumulated excitation energy is emitted by the laser light output from the laser light source D11 and input to the solid-state amplifier 50, and the excitation state when the pulsed light enters the solid-state amplifier 50 is adjusted to be substantially constant. be able to.

  That is, the control unit 100 may variably control the intensity of the laser light output from the laser light source 11 and input to the solid-state amplifier 50 according to the repetition frequency of the pulsed light output from the seed light source 10. Specifically, the control unit 100 outputs the solid light output from the laser light source 11 so that the average power of the light output from the solid-state amplifier 50 is substantially constant regardless of the repetition frequency of the pulsed light output from the seed light source 10. The power of the laser beam input to the amplifier 50 is configured to be adjusted.

  As a result, the solid-state amplifier 50 is stably maintained in an appropriate excitation state regardless of the value of the repetition frequency of the pulsed light while maintaining the power of the excitation light output from the excitation light source 51 constant. Will come to be. The average power (watts) of the pulsed light is obtained by the product of the pulse energy (joule) and the repetition frequency (hertz).

  The oscillation wavelength of a general-purpose semiconductor laser using a Fabry-Perot resonator used for the laser light source 11 is set to the amplification band of the solid-state amplifier 50 capable of amplifying pulsed light having a wavelength of 1064 μm output from the seed light source 10.

  By setting the oscillation wavelength of the laser light source 11 to the amplification band of the solid-state amplifier 50, the excitation energy accumulated in the solid-state amplifier 50 after switching to the output stop state is consumed for amplification of the laser light output from the laser light source 11. Will come to be. If the power of the laser light output from the laser light source 11 is inherently low, even if it is amplified by the solid-state amplifier 50, the nonlinear optical element does not perform wavelength conversion as light having a large peak power.

  As shown in FIG. 7A, if the laser light source 11 capable of oscillating in a narrow band shifted laterally from the center of the amplification band of the solid-state amplifier 50 is used, it is not amplified with a very large gain, and nonlinear optics is used. Wavelength conversion is not performed as light having a large peak power by the element.

  For example, when pulse light having a center wavelength of 1064 nm and a spectrum width of 0.1 to 0.35 nm is output from the seed light source 10, the spectrum light has a half width of about 0.0001 nm and the center wavelength pulse light. The laser light source 11 outputs a laser beam shifted by about 0.1 nm laterally from the center wavelength.

  In addition, if the laser light source 11 that includes the center wavelength of the seed light source 10 and can oscillate with a wider bandwidth than the seed light source 10 is used, the wavelength band that is inherently low in power and wider than the wavelength conversion characteristics of the nonlinear optical elements 60 and 70 is obtained. Are not output as light having a large peak power.

  Further, as shown in FIG. 7B, the oscillation wavelength of the laser light source 11 is set to an amplification band other than the amplification band capable of amplifying the pulsed light output from the seed light source 10 among the amplification bands of the solid-state amplifier 50. May be.

  If there are a plurality of amplification bands of the solid-state amplifier and the oscillation wavelength of the laser light source 11 is set to an amplification band other than the amplification band capable of amplifying the pulsed light output from the seed light source 10, after switching to the output stop state The excitation energy accumulated in the solid-state amplifier 50 is consumed for amplification of the laser light output from the laser light source 11.

  For example, when an Nd: YVO4 crystal having three amplification bands each having a center wavelength of 914 μm, 1064 μm, and 1342 μm is used as the solid-state amplifier 50, the oscillation wavelength of the laser light source 11 is the wavelength of the pulsed light output from the seed light source 10 If the amplification band is set to be different from 1064 μm, the wavelength-converted light is not output because the laser light has a wavelength that is essentially different from the wavelength-convertible band of the nonlinear optical element.

  As shown in FIG. 1, the control unit 100 stores a relationship table that defines the correspondence between the repetition frequency of the pulsed light output from the seed light source 10 and the power of the laser light output from the laser light source 11. 110, and is configured to control the power of laser light output from the laser light source 11 and input to the solid-state amplifier 50 based on a relation table stored in the memory 110.

  For example, when the pulse energy output from the seed light source 10 varies depending on the repetition frequency of the pulse light, the repetition frequency of the pulse light output from the seed light source 10 and the laser light source 11 output in advance and input to the solid state amplifier 50. If the power of the laser beam is specified in the relation table, it can be adjusted appropriately.

  A feedback control circuit that performs feedback control based on the amount of light input from the duplexer 24 to the photodiode PD so that the intensity of the laser light output from the laser light source 11 becomes the intensity read from the relation table is provided to the driver D11. The output intensity of the laser light source 11 is adjusted by the control unit 100 via the driver D11.

  In the present embodiment, a relationship table in which the correspondence relationship between the repetition frequency of the pulsed light and the laser light from the laser light source 11 output from the preceding fiber amplifier 20 is defined is used. When the relational table in which the correspondence relation with the laser light from the laser light source 11 output from the fiber amplifier 30 is used is used, the duplexer 24 may be provided on the output side of the fiber amplifier 30. If the gain of each of the fiber amplifiers 20 and 30 is fixed, the power of the laser light from the laser light source 11 can be obtained by arithmetic processing, so that the duplexer 24 may be provided in any case.

  Instead of such a relationship table, a function having the repetition frequency of the pulsed light output from the seed light source 10 as a variable, and a predetermined function for determining the power of the laser light output from the laser light source 11 It is also possible to define the correspondence. That is, the control unit 100 predefines a correspondence relationship between the repetition frequency of the pulsed light output from the seed light source 10 and the power of the laser light output from the laser light source 11, and the laser light source 11 determines from the correspondence relationship. What is necessary is just to be comprised so that the power of the laser beam output may be controlled.

  When the pulse energy output from the seed light source 10 does not vary depending on the repetition frequency of the pulsed light, the average power of the pulsed light amplified by the solid-state amplifier 50 is calculated from the repetition frequency and the pulse energy, and the value is determined in advance. The laser light source 11 may be driven so that the difference from the target average power becomes the average power of the laser light output from the laser light source 11 and amplified by the solid-state amplifier 50.

  As shown in FIG. 3A, in this embodiment, the control unit 100 is output from the laser light source 11 and input to the solid-state amplifier 50 as the repetition frequency of the pulsed light output from the seed light source 10 decreases. The power of the laser light that is output from the laser light source 11 and input to the solid-state amplifier 50 is decreased as the repetition frequency of the pulse light output from the seed light source 10 is increased. It is comprised so that it may become.

  At this time, as shown in FIG. 3B, the power of the laser light output from the laser light source 11 and input to the solid-state amplifier 50 as the repetition frequency of the pulse light output from the seed light source 10 decreases or increases. As shown in FIG. 3C, as the repetition frequency of the pulsed light output from the seed light source 10 decreases or increases, the solid state output from the laser light source 11 is controlled. It is possible to control the power of the laser light input to the amplifier 50 so as to increase or decrease stepwise.

  As a result, the amplification factor of the pulsed light is adjusted so that the wavelength conversion efficiency of the optical pulse by the subsequent wavelength conversion elements 60 and 70 does not decrease and the solid-state amplifier 50 is not damaged regardless of the repetition frequency of the pulsed light. Become so.

  Further, the control unit 100 drives the laser light source 11 and outputs the solid light from the laser light source 11 when the repetition frequency of the pulsed light output from the seed light source 10 is a predetermined frequency or lower (in this embodiment, 50 kilohertz or lower). The laser beam power input to the amplifier 50 is variably controlled.

  Since the excitation state of the laser active region of the solid-state amplifier is excessive in the region where the repetition frequency of the pulsed light output from the seed light source 10 is low, when the repetition frequency is equal to or lower than a predetermined frequency at which the excessive excitation state is obtained, If the power of the laser light output from the laser light source 11 is adjusted, the solid-state amplifier 50 can be prevented from being damaged. The predetermined frequency at which the laser light source 11 is driven is not limited to 50 kilohertz, and can be set to an arbitrary value of several hundred kilohertz or less according to the specifications of the laser light source device 1.

  As shown in FIG. 3D, the control unit 100 can also control to output the laser light from the laser light source 11 at least during a period different from the output period of the pulsed light from the seed light source 10. . If the laser light source 11 is controlled to output laser light at least during a period different from the pulse light output period from the seed light source 10, it is avoided that the laser active region of the solid-state amplifier 50 is excessively excited during that time. Because it is done.

  It is necessary to change the energy of the pulsed light after wavelength conversion according to the repetition frequency, for example, when it is necessary to maintain the average power of the pulsed light after wavelength conversion output from the laser light source device 1 regardless of the repetition frequency. In some cases, the average power of the light output from the solid-state amplifier 50, that is, the average power of the combined light of the pulse light from the seed light source 10 and the laser light from the laser light source 11, becomes a different value depending on the repetition frequency. As described above, the power of the laser beam output from the laser light source 11 and input to the solid-state amplifier 50 may be adjusted.

  The laser light source device 1 may be configured such that the repetition frequency of the pulsed light output from the seed light source 10 during driving can be adjusted to a different value, or can be set to a predetermined value before the laser light source device 1 is driven. It may be configured to be fixed to the value during driving. Further, the seed light source 10 may be configured to output pulsed light according to a trigger signal input from the outside.

  As described above, the controller 100 sequentially amplifies the pulsed light output from the seed light source 10 by the gain switching method using the fiber amplifiers 20 and 30 and the solid-state amplifier 50, and the amplified pulsed light is nonlinear optical element 60, The power of the laser light that is output from the laser light source 11 that is output from the laser light source 11 that can be combined with the pulsed light that is disposed upstream of the solid-state amplifier 50 and that is output from the seed light source 10. A laser pulsed light generation method is executed in which the above is variably controlled according to the repetition frequency of the pulsed light output from the seed light source 10.

  Then, as the repetition frequency of the pulsed light output from the seed light source 10 decreases, the power of the laser light output from the laser light source 11 and input to the solid-state amplifier 50 is increased stepwise or continuously. A laser that controls the power of the laser light output from the laser light source 11 and input to the solid-state amplifier 50 to decrease stepwise or continuously as the repetition frequency of the pulsed light output from the seed light source 10 increases. A pulsed light generation method is executed.

  As shown in FIG. 4 (a), the deep ultraviolet pulse light wavelength-converted by the laser light source device 1 is narrowed down to a desired beam diameter by the reflection mirror M10 and the condensing optical system L20, and then is directed in the XY directions. Irradiation is directed toward the workpiece W positioned and fixed on a work table T10 having a moving mechanism. A table control unit T11 that controls a moving mechanism in the XY directions and a control unit 100 of the laser light source device 1 are connected via a communication line C.

  As shown in FIGS. 4B and 4C, in order to ensure the processing quality for the processing target W, it is preferable that the laser fluence in the irradiation region of the pulsed light is controlled to be constant. When the lapping rate is S (%), the frequency of the pulsed light is f (hertz), the spot diameter of the pulsed light is d (mm), and the processing speed is V (mm / sec.), The frequency of the pulsed light necessary for making the wrap rate constant is f = V × (1−S / 100) × d.

  The processing speed V is also a relative moving speed with respect to the pulsed light of the processing target W fixed to the work table T10. When the energy of the pulsed light is constant and the moving speed of the processing target W is constant, the frequency of the pulsed light may be maintained constant, but it takes time until the moving speed of the processing target W rises constant. Moreover, it is difficult to keep the moving speed constant when the workpiece W moves in a curved line instead of a linear movement.

  In such a case, if the frequency f of the pulsed light can be adjusted variably, the machining can be started before the moving speed rises constant, and the machining quality can be kept constant even when moving in a curved line. The processing includes various types of processing that can be performed using deep ultraviolet light, such as a cutting process, a groove forming process, a welding process, and an inspection process for the processing target W.

  Therefore, the control unit 100 of the laser light source device 1 receives the movement information of the processing target W from the table control unit T11 via the communication line C, grasps the moving speed of the processing target W, and regardless of the moving speed, the control unit 100 The repetition frequency of the pulse light output from the seed light source 10 and the intensity of the laser light output from the laser light source 11 are variably controlled so that the laser fluence of the pulse light is constant.

  With such a configuration, the wavelength of the optical pulse by the subsequent wavelength conversion elements 60 and 70 is controlled regardless of the repetition frequency by variably controlling the repetition frequency of the pulse light and the power of the laser light output from the laser light source 11. The amplification factor of the pulsed light is adjusted so that the conversion efficiency does not decrease and the solid-state amplifier 50 is not damaged, and the object to be processed can be processed with high processing efficiency.

  That is, the control unit 100 makes the laser fluence of the pulsed light constant regardless of the relative moving speed between the pulsed light output from the nonlinear optical elements 60 and 70 and the object to be processed by the pulsed light. In addition, a laser pulse light generation method for variably controlling the repetition frequency of the pulse light output from the seed light source 10 and the intensity of the laser light output from the laser light source 11 and input to the solid-state amplifier 50 is executed.

Hereinafter, another embodiment will be described.
In the embodiment described above, from the laser light source 11, the average power of the light output from the laser light source 11 and input to the solid state amplifier 50 is substantially constant regardless of the repetition frequency of the pulsed light output from the seed light source 10. Although the example of adjusting the power of the laser beam to be output has been described, the power of the laser beam output from the laser light source 11 is kept constant so that the average power of the light output from the solid-state amplifier 50 is substantially constant. However, the output time may be adjusted while both the power and the output time may be adjusted.

  5A, 5B, and 5C, the frequency characteristics of the pulsed light propagating through each part of the laser light source device 1 are shown on the left side, and the time axis characteristics of the pulsed light are shown on the right side. . Symbols Sn (n is an integer) shown in these figures correspond to the optical signals Sn (n = 1, 2,...) At the output nodes of the respective parts of the laser light source device 1 shown in FIG.

  In response to a trigger signal output from the control unit 100, a narrow-band laser pulse light having a center wavelength of 1064 nm is output at a predetermined cycle from the DFB laser that is the seed light source 10 (see FIGS. 5A and 6A). . In the process in which the pulsed light output from the seed light source 10 is guided to the fiber amplifier 20 and amplified, the spectrum width unnecessarily widens due to self-phase modulation, Raman scattering, etc., and further, ASE noise is generated and S of the optical pulse The / N ratio decreases (see FIG. 5B). In the process where such pulsed light is guided to the subsequent fiber amplifier 30 and amplified, the bandwidth is further increased, and the ASE noise level is increased (see FIGS. 5C and 6B).

  In the region where the repetition frequency of the pulsed light is sufficiently higher than 100 kilohertz, the excitation energy accumulated in the solid-state amplifier 50 is used to amplify optical pulses and ASE noise that have a wider band than the wavelength range that can be converted by the wavelength conversion unit 1D. As a result, the wavelength conversion efficiency may be reduced.

  As shown in FIG. 8, in preparation for such a case, an acousto-optic modulation functioning as an optical switch element 40 is provided with an acousto-optic element between the collimator CL1 disposed at the rear stage of the fiber amplifier 30 and the solid-state amplifier 50. It is preferable to arrange an AOM (Acousto-Optic Modulator).

  When a gate signal is output from the control unit 100 to the RF driver D2 that drives the acoustooptic modulator AOM that is the optical switch element 40, the acoustooptic element is applied by a transducer (piezoelectric conversion element) to which a high frequency signal is applied from the RF driver D2. The diffraction grating is generated in the crystal constituting the diffracted light, and the diffracted light of the pulsed light incident on the acoustooptic device is incident on the reflection mirror M1.

  When the RF driver D2 is stopped, the pulsed light incident on the acoustooptic device passes through without being diffracted and does not enter the reflection mirror M1. The light that has passed through the acoustooptic device when the RF driver D2 is stopped is attenuated by the optical damper.

  That is, the diffracted light propagates from the fiber amplifier 30 to the solid-state amplifier 50 when the optical switch element 40 is turned on by the gate signal, and the light propagates from the fiber amplifier 30 to the solid-state amplifier 50 when the optical switch element 40 is turned off by the gate signal. Be blocked.

  As shown in FIG. 6C, the control unit 100 outputs the pulse light output period from the seed light source 10 when the repetition frequency of the pulse light output from the seed light source 10 is higher than a predetermined frequency (FIG. 6C ) To allow light propagation in the section Ton) and to prevent the light switch element 40 from propagating in a period different from the output period of the pulsed light from the seed light source 10 (section Toff in FIG. 6C). Configured to control. With such a configuration, the excitation energy accumulated in the solid-state amplifier 50 is efficiently used to amplify an optical pulse in a band where wavelength conversion is possible, and the pulsed light is amplified efficiently (see FIG. 6D). Then, pulse light with a large peak power is output from the nonlinear optical element. That is, the optical switch element 40 is caused to function as a filter for removing ASE noise in the time domain.

  The predetermined frequency for starting the control of the optical switch element 40 may be the same frequency as 50 kilohertz for starting the control of the laser light source 11, or may be set to a higher frequency. The laser light source 11 is preferably stopped when the control of the optical switch element 40 is started for the purpose of blocking the ASE noise.

  “The output period of the pulsed light from the seed light source” in which the optical switch element 40 is on-controlled by the control unit 100 does not mean only the entire period in which the pulsed light is output from the seed light source 10, but non-linear optics. It may be a partial period as long as the peak power of the pulsed light converted by the elements 60 and 70 exhibits an appropriate value, and may be slightly before and after the period during which the pulsed light is output from the seed light source 10. It is a concept that includes various periods.

  The “period different from the output period of the pulsed light from the seed light source” in which the optical switch element 40 is controlled to be off by the control unit 100 is the entire period between the output periods of the plurality of pulsed light, that is, there is no pulsed light. It does not mean only the entire period, but includes a part of the period as long as it can reduce the waste of the active region energy of the solid-state amplifier 50 excited by the excitation light source 51 due to ASE noise. This is a concept.

  Regardless of the repetition frequency of the pulsed light output from the seed light source 10, the laser light output from the laser light source 11 and input to the solid-state amplifier 50 so that the average power of the light output from the solid-state amplifier 50 is substantially constant. In order to adjust the power, such an optical switch element 40 can be used.

  By controlling the drive timing of the optical switch element 40 and adjusting the time during which the laser light output from the laser light source 11 is input to the solid-state amplifier 50, the average power of the light output from the solid-state amplifier 50 is substantially constant. Can be adjusted.

  Although an example in which an acoustooptic device that turns on or off first-order diffracted light by turning on or off an ultrasonic transducer has been described as the optical switch element 40 has been described. It is also possible to use an electro-optic element that turns light on and off.

  Further, whether or not the output of the fiber amplifier 30 is propagated to the solid-state amplifier 50 by using a micro peristaltic mirror (mirror composed of MEMS (Micro Electro Mechanical Systems)) manufactured by micromachining technology as the optical switch element 40. May be configured to be switched according to a slight swing angle of the swing mirror. Alternatively, a polarization device capable of dynamically switching the polarization state and controlling transmission and blocking of light may be used. In other words, the optical switch element only needs to be composed of a dynamic optical element.

  In the embodiment described above, an example has been described in which a DFB laser is used as a seed light source and a gain switching method is applied to the DFB laser to generate pulsed light having a higher intensity than that in a steady state in a single longitudinal mode. The present invention only needs to use a semiconductor laser as a seed light source, and a general Fabry-Perot type semiconductor laser other than a DFB laser can also be used.

  The present invention is not limited to a seed light source with an oscillation wavelength of 1064 nm. For example, it is possible to select a seed light source with a different wavelength depending on the application, such as 1030 nm, 1550 nm, and 976 nm. Furthermore, it is possible to generate harmonics, sum frequencies, and difference frequencies having these wavelengths as fundamental waves through a nonlinear optical element. Nonlinear optical elements other than those described above can be used as the nonlinear optical element. For example, a BBO crystal, a KBBF crystal, an SBBO crystal, a KABO crystal, a BABO crystal, or the like can be used instead of the CLBO crystal.

  The plurality of embodiments described above are all descriptions of one embodiment of the present invention, and the scope of the present invention is not limited by the description. Needless to say, the specific circuit configuration of each part and the optical elements used in the circuit can be appropriately selected or modified as long as the effects of the present invention can be achieved.

1: Laser light source device 10: seed light source (first light source)
11: Laser light source (second light source)
20, 30: fiber amplifier 40: optical switch element 50: solid state amplifier 60, 70: nonlinear optical element 100: control unit

Claims (14)

A first light source that outputs pulsed light by a gain switching method, a fiber amplifier that amplifies pulsed light output from the first light source, a solid-state amplifier that amplifies pulsed light output from the fiber amplifier, and the solid-state amplifier A non-linear optical element that converts the wavelength of the pulsed light output from and outputs the light,
A second light source that outputs laser light that is arranged upstream of the solid-state amplifier and can be combined with pulsed light output from the first light source;
A controller that variably controls the power of the laser light output from the second light source and input to the solid-state amplifier in accordance with the repetition frequency of the pulsed light output from the first light source;
A laser light source device.   The control unit increases the power of laser light output from the second light source and input to the solid-state amplifier stepwise or continuously as the repetition frequency of the pulsed light output from the first light source decreases. As the repetition frequency of the pulsed light output from the first light source increases, the power of the laser light output from the second light source and input to the solid-state amplifier is stepwise or continuously. 2. The laser light source device according to claim 1, wherein the laser light source device is controlled to be low.   The control unit variably controls the power of laser light output from the second light source and input to the solid-state amplifier when a repetition frequency of pulsed light output from the first light source is equal to or lower than a predetermined frequency. Item 3. The laser light source device according to Item 1 or 2.   4. The laser light source according to claim 1, wherein the control unit performs control so that laser light is output from the second light source at least during a period different from an output period of pulse light from the first light source. apparatus.   The control unit outputs the solid state amplifier from the second light source so that the average power of the light output from the solid state amplifier is substantially constant regardless of the repetition frequency of the pulsed light output from the first light source. The laser light source device according to claim 1, wherein the power of the laser beam input to the laser beam is adjusted.   The control unit preliminarily defines a correspondence relationship between the repetition frequency of the pulsed light output from the first light source and the power of the laser light output from the second light source and input to the solid-state amplifier. 6. The laser light source device according to claim 1, wherein the laser light power output from the second light source and input to the solid-state amplifier is controlled based on the laser light source.   7. The laser light source device according to claim 1, wherein an oscillation wavelength of the second light source is set to an amplification band of the solid-state amplifier capable of amplifying pulsed light output from the first light source.   7. The oscillation wavelength of the second light source is set to an amplification band other than an amplification band capable of amplifying pulsed light output from the first light source among the amplification bands of the solid-state amplifier. A laser light source device according to claim 1.   The controller controls the first fluence so that a laser fluence of the pulsed light is constant regardless of a relative moving speed between the pulsed light output from the nonlinear optical element and a processing target processed by the pulsed light. 9. The laser light source device according to claim 1, wherein the laser light source device variably controls the repetition frequency of pulsed light output from one light source and the power of laser light output from the second light source and input to the solid-state amplifier. Further comprising an optical switch element disposed between the fiber amplifier and the solid-state amplifier to allow or block the propagation of light from the fiber amplifier to the solid-state amplifier;
The controller allows light to propagate during an output period of the pulsed light from the first light source when a repetition frequency of the pulsed light output from the first light source is higher than a predetermined frequency. 10. The laser light source device according to claim 1, wherein the optical switch element is configured to control propagation of light during a period different from an output period of the pulsed light. A laser pulse light generation method in which pulse light output from a first light source by a gain switching method is sequentially amplified by a fiber amplifier and a solid-state amplifier, and the amplified pulse light is wavelength-converted by a nonlinear optical element and output.
The power of the laser beam output from the second light source that is arranged upstream of the solid-state amplifier and can be combined with the pulsed light output from the first light source and input to the solid-state amplifier is output from the first light source. A laser pulse light generation method variably controlled according to the repetition frequency of pulse light.   As the repetition frequency of the pulsed light output from the first light source decreases, the power of the laser light output from the second light source and input to the solid-state amplifier is increased stepwise or continuously. As the repetition frequency of the pulsed light output from the first light source increases, the power of the laser light output from the second light source and input to the solid-state amplifier is controlled to decrease stepwise or continuously. The laser pulse light generation method according to claim 11.   Laser output from the second light source and input to the solid-state amplifier so that the average power of the light output from the solid-state amplifier is substantially constant regardless of the repetition frequency of the pulsed light output from the first light source. The laser pulse light generation method according to claim 11 or 12, wherein the light power is adjusted.   The pulse light output from the first light source is constant so that the laser fluence is constant regardless of the relative moving speed between the pulse light output from the nonlinear optical element and the object to be processed by the pulse light. 14. The laser pulse light generation method according to claim 11, wherein the repetition frequency and the power of the laser light output from the second light source and input to the solid-state amplifier are variably controlled.

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