JP2018174206A - Laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser device capable of suppressing variations in measurement results of the intensity of a signal light from occurring.SOLUTION: A laser device 1 of the present invention includes: a signal light source 3 emitting a signal light having a correlation between a peak intensity and a pulse width; an optical component 30 to branch monitor light that is a part of the signal light; a light receiving unit 31 to receive the monitor light branched by the optical component 30; a measurement unit 32 to measure a pulse width of the monitor light on the basis of an output from the light receiving unit 31; and a control unit 33 to control the signal light source 3 such that the signal light has an intensity in a predetermined range, in accordance with an output from the measurement unit 32.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laser apparatus capable of suppressing variations in measurement results of signal light intensity.

  A fiber laser device that amplifies and emits signal light with a rare-earth-doped fiber is used as one of laser devices used for processing machines that perform processing using laser light and medical devices such as a scalpel using laser light. ing. As one of such fiber laser devices, there is known an MO-PA type fiber laser device that amplifies and emits signal light emitted from a master oscillator (MO) by a power amplifier (PA). It has been.

  In the MO-PA type fiber laser device, if the intensity of the signal light incident on the power amplifier from the master oscillator is extremely weak while the excitation light is incident on the amplification optical fiber in the power amplifier, the amplification light The excited state of the active element added to the fiber may not be lowered by the signal light. In this case, the excited state of the active element added to the amplification optical fiber may be excessively increased, and as a result, an unintended giant pulse may be oscillated. Such a giant pulse may damage the excitation light source and the seed light source, and may cause the operation of the laser device to become unstable. Therefore, it is preferable to measure the intensity of the signal light emitted from the master oscillator and perform feedback control so that the intensity of the signal light emitted from the master oscillator is increased to some extent.

  The following Patent Document 1 includes a branching unit that branches a part of light emitted from an optical amplification fiber and extracts sampling light, a photoelectric conversion unit that generates an electrical signal according to the intensity of sampling light, and the electric A laser device is disclosed that includes a control unit that controls the intensity of light emitted from an optical amplification fiber according to a signal. According to this laser apparatus, the intensity of light emitted from the optical amplification fiber can be estimated by measuring the intensity of the sampling light, and the intensity of the light can be feedback-controlled. Therefore, the intensity of the signal light can be controlled by applying this technique to the estimation of the intensity of the signal light emitted from the master oscillator.

JP 2012-182204 A

  However, in the case of the laser device disclosed in Patent Document 1, the measurement result of the intensity of the sampling light may vary depending on the fusion of the branch portions and the variation in the performance of the photoelectric conversion unit. If the measurement result of the intensity of the sampling light varies, the estimated output light intensity also varies. Therefore, for example, in the case of mass production of the laser device as in Patent Document 1, the output light estimated in each laser device is the same even though the intensity of the actual output light emitted from each laser device is the same. Intensity may vary.

  Therefore, an object of the present invention is to provide a laser device that can suppress variation in the measurement result of the intensity of signal light.

  A laser apparatus according to an aspect of the present invention includes a signal light source that emits signal light whose pulse width increases as the peak intensity increases, an optical component that branches monitor light that is part of the signal light, and the light A light receiving unit that receives the monitor light branched by a component, a measurement unit that measures the pulse width of the monitor light based on an output from the light receiving unit, and the measurement unit according to an output from the measurement unit And a control unit that controls the signal light source so that the pulse width of the monitor light measured in step S is equal to or greater than a predetermined value.

  In this laser apparatus, a signal light source that emits signal light whose pulse width increases as the peak intensity increases is used. That is, there is a positive correlation between the peak intensity of the signal light and the pulse width. In the laser apparatus, the monitor light that is a part of the signal light is branched by the optical component, and the pulse width of the monitor light is measured. The monitor light is a part of the signal light, and there is a positive correlation between the pulse width of the monitor light and the pulse width of the signal light. Therefore, the peak intensity of the signal light can be indirectly measured by measuring the pulse width of the monitor light. Furthermore, when measuring the pulse width of the monitor light, variations in measurement results due to variations in the performance of the optical components and the light receiving unit can be suppressed as compared to the case where the intensity of the monitor light is measured. Therefore, according to the laser apparatus of the said invention, it can suppress that dispersion | variation arises in the measurement result of the intensity | strength of signal light. In addition, by controlling the signal light source so that the pulse width of the monitor light measured as described above becomes a predetermined value or more, the intensity of the signal light emitted from the signal light source becomes a desired value or more. Can be controlled.

  Note that in this specification, signal light is not limited to light containing a signal.

  The laser device may further include an optical amplifier having an amplification optical fiber that amplifies the signal light, and a pumping light source that emits pumping light incident on the amplification optical fiber, and the control unit includes: It is preferable to stop the emission of the excitation light from the excitation light source when the pulse width of the monitor light measured by the measurement unit becomes equal to or less than a specific value smaller than the predetermined value.

  In such a laser device, as described above, the control unit controls the signal light source so that the pulse width of the monitor light to be measured becomes a predetermined value or more, so that the intensity of the signal light becomes a desired value or more. Can be controlled. Therefore, when the pulse width of the monitor light measured by the measurement unit is not more than a specific value smaller than the predetermined value, the intensity of the signal light is unintentionally reduced. In such a state, the operation of the laser device may become unstable as described above. In such a case, the emission of the pumping light from the pumping light source provided in the optical amplifier is stopped, so that the unstable operation of the laser device can be suppressed.

  A laser apparatus according to another aspect of the present invention includes a signal light source that emits signal light whose pulse width decreases as the peak intensity increases, and an optical component that branches monitor light that is part of the signal light. A light receiving unit that receives the monitor light branched by the optical component, a measurement unit that measures a pulse width of the monitor light based on an output from the light receiving unit, and an output from the measurement unit, A control unit that controls the signal light source so that a pulse width of the monitor light measured by the measurement unit is a predetermined value or less.

  In this laser apparatus, a signal light source that emits signal light whose pulse width decreases as the peak intensity increases is used. That is, there is a negative correlation between the peak intensity of the signal light and the pulse width. In the laser apparatus, the monitor light that is a part of the signal light is branched by the optical component, and the pulse width of the monitor light is measured. As described above, there is a positive correlation between the pulse width of the monitor light and the pulse width of the signal light, and the peak intensity of the signal light is indirectly measured by measuring the pulse width of the monitor light. Can do. Furthermore, as described above, when measuring the pulse width of the monitor light, it is possible to suppress variations in measurement results due to variations in the performance of the optical components and the light receiving unit as compared with the case where the intensity of the monitor light is measured. Therefore, even with the laser device, it is possible to suppress variation in the measurement result of the intensity of the signal light. Further, by controlling the signal light source so that the pulse width of the monitor light measured as described above becomes a predetermined value or less, the intensity of the signal light can be controlled to become a desired value or more.

  In the laser device according to another aspect of the present invention, an optical amplifier further comprising: an amplification optical fiber that amplifies the signal light; and an excitation light source that emits excitation light incident on the amplification optical fiber. The control unit preferably stops emission of the excitation light from the excitation light source when a pulse width of the monitor light measured by the measurement unit is equal to or greater than a specific value larger than the predetermined value. .

  In such a laser apparatus, as described above, the control unit controls the signal light source so that the pulse width of the monitor light to be measured is not more than a predetermined value, so that the intensity of the signal light becomes not less than a desired value. Can be controlled. Therefore, when the pulse width of the monitor light measured by the measurement unit becomes a specific value greater than the predetermined value, the intensity of the signal light is unintentionally reduced. In such a state, instability of the operation of the laser device can be suppressed by stopping the emission of the excitation light from the excitation light source provided in the optical amplifier.

  Moreover, in the laser apparatus according to the one aspect and the other aspect of the present invention, the control unit controls the signal light source so that a pulse width of the monitor light measured by the measurement unit falls within a predetermined range. Is preferred.

  As described above, there is a correlation between the pulse width of the monitor light measured by the measurement unit and the peak intensity of the signal light. Therefore, by controlling the signal light source so that the pulse width of the monitor light measured by the measurement unit falls within a predetermined range, signal light having a desired range of intensity can be emitted from the signal light source.

  As described above, according to the present invention, there is provided a laser device that can suppress variation in the measurement result of the intensity of signal light.

It is a figure which shows the laser apparatus which concerns on 1st Embodiment of this invention. It is a graph which shows the relationship between the pulse width of signal light, and a peak voltage. It is a figure which shows the laser apparatus which concerns on 2nd Embodiment of this invention. It is a graph which shows the relationship between the pulse width of signal light, and a peak voltage.

  Hereinafter, the form for implementing the laser apparatus concerning this invention is illustrated with an accompanying drawing. The embodiments exemplified below are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The present invention can be modified and improved from the following embodiments without departing from the spirit of the present invention.

(First embodiment)
FIG. 1 is a diagram showing a laser apparatus according to the first embodiment of the present invention.

  As shown in FIG. 1, the laser device 1 of this embodiment includes a signal light source 3 and an optical amplifier 4 that amplifies signal light emitted from the signal light source 3. The signal light source 3 includes a pulse light source 2, a wavelength conversion unit 19, and an optical filter 20. This laser device 1 is an MO-PA type fiber laser device in which the pulse light source 2 is a master oscillator and the optical amplifier 4 is a power amplifier. In addition, the laser device 1 is provided between the signal light source 3 and the optical amplifier 4 to branch a part of the signal light emitted from the signal light source 3, and the signal light branched by the optical component 30. The light receiving unit 31 that receives a part of the monitor light, the measurement unit 32 that measures the pulse width of the monitor light based on the output from the light receiving unit 31, and the signal light source 3 and the light according to the output from the measurement unit 32 A control unit 33 that controls the amplifier 4 is further provided as a main configuration.

  The pulsed light source 2 includes an excitation light source 11, an amplification optical fiber 12, an optical combiner 13, an optical fiber 41 connected to one side of the amplification optical fiber 12, a first FBG (Fiber Bragg Grating) 17 provided in the optical fiber 41, An optical fiber 42 connected to the other side of the amplification optical fiber 12, a Q switch 18 provided on the opposite side of the optical fiber 42 from the amplification optical fiber 12, and an optical fiber 42 of the Q switch 18 connected to the opposite side. Optical fiber 43, second FBG 16 provided in the optical fiber 43, wavelength conversion unit 19 connected to the opposite side of the optical fiber 43 from the Q switch 18, and an optical filter 20 on which light transmitted through the wavelength conversion unit 19 enters. Is provided as a main configuration. In the pulse light source 2, a resonator is constituted by the amplification optical fiber 12, the first FBG 17, and the second FBG 16.

  The excitation light source 11 includes a plurality of laser diodes, and emits excitation light having a wavelength for exciting an active element added to the amplification optical fiber 12 described later, for example, excitation light having a wavelength of 915 nm. In addition, pumping light emitted from each laser diode of the pumping light source 11 enters the optical fiber 15 and propagates through the optical fiber 15. An example of the optical fiber 15 is a multimode fiber. In this case, the pumping light propagates in the optical fiber 15 as multimode light.

  The amplification optical fiber 12 includes a core, an inner cladding that surrounds the outer peripheral surface of the core without a gap, an outer cladding that covers the outer peripheral surface of the inner cladding, and a coating layer that covers the outer peripheral surface of the outer cladding. It is a fiber. The core is made of quartz to which an active element that is excited by excitation light emitted from the excitation light source 11 is added. Examples of such active elements include rare earth elements, and examples of rare earth elements include ytterbium (Yb), thulium (Tm), cerium (Ce), neodymium (Nd), europium (Eu), and erbium (Er). Can be mentioned. Furthermore, bismuth (Bi) etc. can be mentioned as an active element other than a rare earth element. The refractive index of the inner cladding is lower than the refractive index of the core, and the refractive index of the outer cladding is further lower than the refractive index of the inner cladding. Therefore, in addition to the active element, for example, an element such as germanium (Ge) that increases the refractive index is added to the core. In this case, the cladding is made of, for example, pure quartz to which no dopant is added. The outer cladding is made of, for example, an ultraviolet curable resin, and the coating layer is made of, for example, an ultraviolet curable resin that is different from the resin constituting the outer cladding.

  The optical fiber 41 connected to one side of the amplifying optical fiber 12 includes a core to which no active element is added, an inner cladding that surrounds the outer peripheral surface of the core without a gap, and an outer surface that covers the outer peripheral surface of the inner cladding. A clad and a coating layer covering the outer clad are provided as main components. The core of the optical fiber 41 has substantially the same configuration as the core of the amplification optical fiber 12 except that no active element is added. The core of the optical fiber 41 is connected to the core of the amplification optical fiber 12, and the inner cladding of the optical fiber 41 is connected to the inner cladding of the amplification optical fiber 12. Further, a first FBG 17 as a first mirror is provided in the core of the optical fiber 41. Thus, the first FBG 17 is provided on one side of the amplification optical fiber 12. The first FBG 17 has a portion where the refractive index is periodically increased along the longitudinal direction of the optical fiber 41, and the active element of the amplification optical fiber 12 in the excited state is adjusted by adjusting this cycle. Is configured to reflect light of at least a part of the light emitted. The reflectivity of the first FBG 17 is higher than the reflectivity of the second FBG 16 which will be described later, and it is preferable to reflect light of a desired wavelength of 90% or more, and more than 99%, of the light emitted by the active element. preferable.

  In the optical combiner 13, the core of each optical fiber 15 and the inner cladding of the optical fiber 41 are connected. Therefore, the optical fiber 15 through which the pumping light emitted from each laser diode provided in the pumping light source 11 propagates and the inner cladding of the amplification optical fiber 12 are optically coupled via the inner cladding of the optical fiber 41. Yes.

  The optical fiber 42 connected to the other side of the amplification optical fiber 12 includes a core to which no active element is added, a clad surrounding the outer peripheral surface of the core without a gap, and a coating layer covering the outer peripheral surface of the clad. Is provided as a main configuration. The core of the optical fiber 42 is connected to the core of the amplification optical fiber 12, and the cladding of the optical fiber 42 is connected to the inner cladding of the amplification optical fiber 12. A Q switch 18 is optically coupled to the side of the optical fiber 42 opposite to the amplification optical fiber 12.

  The Q switch 18 is composed of, for example, an acoustic optical element (AOM: Acoustic Optic Modulation) that can be controlled from the outside with an electrical signal, and is controlled so that light from the optical fiber 42 repeats a low-loss state and a high-loss state. Is done. By controlling the Q switch 18 in this way, the light emitted from the pulse light source 2 becomes pulsed. The pulse time shape of this light is a Gaussian distribution shape.

  The optical fiber 43 mainly includes a core to which no active element is added, a clad that surrounds the outer peripheral surface of the core without a gap, and a coating layer that covers the outer peripheral surface of the clad. In addition, a second FBG 16 as a second mirror is provided in the core of the optical fiber 43. Thus, the second FBG 16 is provided on the other side of the amplification optical fiber 12. The second FBG 16 has a portion where the refractive index is increased at a constant period along the longitudinal direction of the optical fiber 43, and at least some of the light reflected by the first FBG 17 is lower than the first FBG 17. It is configured to reflect with reflectivity. A wavelength conversion unit 19 is provided on the opposite side of the optical fiber 43 from the Q switch 18 side.

  Light enters the wavelength conversion unit 19 through the optical fiber 43. The wavelength conversion unit 19 is made of, for example, an optical fiber, and stimulated Raman scattering occurs when light enters. The wavelength conversion unit 19 of the present embodiment is configured to generate primary scattered light of incident light.

  The light transmitted through the wavelength conversion unit 19 enters the optical filter 20. The optical filter 20 suppresses transmission of light emitted from the pulse light source 2 and transmits primary scattered light generated in the wavelength conversion unit 19. That is, the optical filter 20 is a high-pass filter that transmits the primary scattered light. Examples of such an optical filter 20 include an optical filter in which a filter film is formed on glass. An example of such a filter film is a dielectric multilayer film in which a plurality of types of dielectric films are repeatedly laminated. Further, the optical filter 20 is preferably disposed with the filter surface inclined with respect to the traveling direction of the light emitted from the wavelength conversion unit 19. This is because when the optical filter 20 reflects non-transmitted light, the reflected light can be easily taken out by arranging the filter surface inclined. The light transmitted through the optical filter 20 propagates through the optical fiber 44 and is emitted from the signal light source 3 as signal light.

  The optical component 30 is an optical coupler that is disposed between the signal light source 3 and the optical amplifier 4 and connects the exit end of the optical fiber 44 to the entrance end of the optical fiber 45 and the entrance end of the optical fiber 46. The signal light emitted from the signal light source 3 is incident on the optical component 30 through the optical fiber 44. In the optical component 30, a part of the signal light is branched as monitor light and incident on the optical fiber 46. The other part is incident on the optical fiber 45. The optical fiber 44 is an optical fiber that optically couples the signal light source 3 and the optical component 30. The optical fiber 45 is an optical fiber that optically couples the optical component 30 and the optical amplifier 4. The optical fiber 46 is an optical fiber that optically couples the optical component 30 and the light receiving unit 31.

  The optical amplifier 4 includes a pumping light source 21, an amplification optical fiber 22, and an optical coupler 23 as main components.

  The excitation light source 21 includes a plurality of laser diodes, and emits excitation light having a wavelength for exciting an active element added to the amplification optical fiber 22 described later, for example, excitation light having a wavelength of 915 nm. Further, the pumping light emitted from each laser diode of the pumping light source 21 enters the optical fiber 25 and propagates through the optical fiber 25. Examples of the optical fiber 25 include a multimode fiber. In this case, the pumping light propagates in the optical fiber 25 as multimode light.

  The amplification optical fiber 22 has substantially the same configuration as the amplification optical fiber 12.

  The optical coupler 23 connects the optical fiber 45 and the emission ends of the respective optical fibers 25 and the incident end of the amplification optical fiber 22. Specifically, in the optical coupler 23, the core of the optical fiber 45 is connected to the core of the amplification optical fiber 22, and the core of each optical fiber 25 is connected to the inner cladding of the amplification optical fiber 22. Has been. Therefore, the signal light emitted from the signal light source 3 enters the core of the amplification optical fiber 22, and the excitation light emitted from the excitation light source 21 enters the inner cladding of the amplification optical fiber 22. In the amplification optical fiber 22, the power of the signal light is amplified as will be described later, and light having a high power density is emitted from the optical amplifier 4 through the delivery fiber 50.

  The light receiving unit 31 is optically coupled to the optical component 30 via the optical fiber 46 and receives monitor light that is part of the signal light branched by the optical component 30. An example of the light receiving unit 31 is a photodiode. The light receiving unit 31 outputs an electrical signal obtained by photoelectrically converting the received monitor light.

  The measuring unit 32 is electrically connected to the light receiving unit 31, and an electric signal from the light receiving unit 31 is input to the measuring unit 32. The measuring unit 32 measures the pulse width of the monitor light based on the output from the light receiving unit 31.

  The control unit 33 is electrically connected to the measurement unit 32, the signal light source 3, and the optical amplifier 4, and controls the signal light source 3 and the optical amplifier 4 according to the electrical signal from the measurement unit 32. The control unit 33 includes, for example, a CPU (Central Processing Unit). The control unit 33 according to the present embodiment signals a signal when the pulse width measured by the measurement unit 32 deviates from the predetermined range so that the pulse width of the monitor light measured by the measurement unit 32 falls within the predetermined range. The intensity of the signal light emitted from the light source 3 is feedback controlled. In addition, the control unit 33 of the present embodiment provides the excitation provided in the optical amplifier 4 when the pulse width of the monitor light measured by the measurement unit 32 is equal to or less than a specific value that is smaller than the lower limit value of the predetermined range. Control is performed to stop emission of excitation light from the light source 21.

  Next, the operation and action of such a laser device 1 will be described.

  First, when pumping light is emitted from each laser diode of the pumping light source 11, the pumping light enters the inner cladding of the amplification optical fiber 12 through the inner cladding of the optical fiber 41. The inner cladding is sandwiched between a core having a higher refractive index than the inner cladding and an outer cladding having a lower refractive index than the inner cladding, and the excitation light incident on the inner cladding mainly propagates through the inner cladding and enters the core. Thus, the excitation light incident on the core excites the active element added to the core. The active element brought into an excited state emits spontaneous emission light having a specific wavelength. This spontaneously emitted light propagates through the core of the amplification optical fiber 12, and a part of the wavelength light is reflected by the first FBG 17, and the light having the wavelength reflected by the second FBG 16 is reflected by the first FBG 17. It is reflected by the 2FBG 16 and reciprocates in the resonator. Then, when the light reflected by the first FBG 17 and the second FBG 16 propagates through the core of the optical fiber for amplification 12, stimulated emission occurs, the light is amplified, and the gain and loss in the resonator become equal. Oscillates. A part of the light resonating between the first FBG 17 and the second FBG 16 passes through the second FBG 16 and is emitted from the pulse light source 2.

  However, a Q switch 18 is provided between the amplification optical fiber 12 and the second FBG 16. The Q switch 18 performs a switching operation so as to repeat a low-loss and high-loss state of light at a predetermined fixed period. Then, pulsed light synchronized with the switching operation is generated in the Q switch 18. The pulse time waveform of this light has a Gaussian distribution shape. Further, the pulsed light generated in this way propagates through the amplification optical fiber 12 containing the active element excited as described above, so that the peak intensity increases as the pulse width decreases. Light is emitted from the pulsed light source 2. That is, the pulsed light emitted from the pulsed light source 2 has a negative correlation between the pulse width and the peak intensity.

  The light emitted from the pulse light source 2 propagates mainly through the core of the optical fiber 43 and enters the wavelength conversion unit 19. In the wavelength conversion unit 19, the light component having a power density higher than a specific power density among the incident light is used as the primary scattered light. Then, the wavelength conversion unit 19 emits light that is not wavelength-converted and primary scattered light. Thus, the light emitted from the wavelength conversion unit 19 enters the optical filter 20.

  As described above, the optical filter 20 suppresses transmission of light emitted from the pulse light source 2 and transmits primary scattered light of this light. Although the pulse light emitted from the pulse light source 2 has a negative correlation between the pulse width and the peak intensity, the pulse width of the primary scattered light increases as the peak intensity increases. Thus, the light passing through the optical filter 20 is emitted as signal light from the signal light source 3 through the optical fiber 44. Therefore, the signal light source 3 of the present embodiment emits signal light whose pulse width increases as the peak intensity increases.

  A part of the signal light propagating through the optical fiber 44 is branched at the optical component 30. In the optical component 30, as described above, the monitor light that is a part of the signal light incident from the optical fiber 44 is branched and incident on the optical fiber 46, and the other part of the signal light is incident on the optical fiber 45. To do.

  The signal light that enters the optical amplifier 4 via the optical fiber 45 enters the core of the amplification optical fiber 22 from the optical coupler 23. In addition, excitation light is emitted from each laser diode of the excitation light source 21. Then, the pumping light emitted from each laser diode propagates through the optical fiber 25 and enters the inner cladding of the amplification optical fiber 22 from the optical coupler 23.

  Thus, the signal light incident on the core of the amplification optical fiber 22 from the optical coupler 23 propagates through the core, and the excitation light incident on the inner cladding of the amplification optical fiber 22 propagates mainly through the inner cladding. In the amplification optical fiber 22, when the excitation light passes through the core, it is absorbed by the active element added to the core and the active element is excited. In the period when the signal light is not incident on the amplification optical fiber 22, the excited state of the active element is high. On the other hand, when pulsed signal light is incident on the amplification optical fiber 22, the excited active element causes stimulated emission by the signal light, and the power of the signal light is amplified by this stimulated emission. Pulsed light with amplified power density is emitted. Light emitted from the amplification optical fiber 22 is emitted from the laser device 1 via the delivery fiber 50.

  On the other hand, the monitor light that is branched in the optical component 30 and enters the optical fiber 46 is received by the light receiving unit 31. The light receiving unit 31 photoelectrically converts the received light and outputs an electrical signal. An electrical signal output from the light receiving unit 31 is input to the measuring unit 32.

  The measuring unit 32 measures the pulse width of the monitor light based on the output from the light receiving unit 31. For example, the measuring unit 32 measures the time when the electric signal input from the light receiving unit 31 has an intensity greater than a predetermined threshold. This time measurement is performed, for example, by counting the number of clocks using an FPGA (field-programmable gate array). The time thus measured is the pulse width of the monitor light. The measurement of the pulse width of the monitor light is reset for each pulse using a pulse oscillation clock.

  FIG. 2 is a graph showing the relationship between the pulse width [ns] of the signal light emitted from the signal light source 3 and the peak voltage [V] of the electrical signal resulting from the peak intensity of the monitor light obtained by the light receiving unit 31. . As described above, the pulse width of the pulsed light transmitted through the wavelength conversion unit 19 increases as the peak intensity increases. Therefore, the positive width as shown in FIG. 2 is present between the pulse width of the signal light emitted from the signal light source 3 of the present embodiment and the peak voltage of the electric signal generated due to the peak intensity of the monitor light. There is a correlation. Thus, the signal light source 3 of the present embodiment emits signal light whose pulse width increases as the peak intensity increases. Further, in the laser apparatus 1, the monitor light that is a part of the signal light is branched by the optical component 30 and the pulse width of the monitor light is measured. The monitor light is a part of the signal light, and there is a positive correlation between the pulse width of the monitor light and the pulse width of the signal light. Therefore, the peak intensity of the signal light can be indirectly measured by measuring the pulse width of the monitor light.

  When a signal indicating the pulse width of the monitor light is input from the measurement unit 32, the control unit 33 controls the signal light source 3 and the optical amplifier 4 based on the magnitude of the pulse width.

  When the control unit 33 according to the present embodiment determines that the pulse width of the monitor light measured by the measurement unit 32 is smaller than the lower limit of the predetermined range, the peak intensity of the signal light emitted from the signal light source 3 is increased. The signal light source 3 is controlled. Specifically, the intensity of the excitation light emitted from the excitation light source 11 is increased. As described above, there is a correlation between the pulse width of the monitor light and the peak intensity of the signal light, and the pulse width of the monitor light measured by the measurement unit 32 is smaller than the lower limit of the predetermined range. Indicates that the peak intensity of light is less than the desired value. Therefore, the feedback control for increasing the peak intensity of the signal light emitted from the signal light source 3 is repeated until the pulse width of the monitor light measured by the measurement unit 32 becomes equal to or greater than the lower limit of the predetermined range. Thereby, the peak intensity of the signal light emitted from the signal light source 3 can be controlled to be equal to or higher than the lower limit of the desired range.

  In addition, when the control unit 33 of the present embodiment determines that the pulse width of the monitor light measured by the measurement unit 32 is larger than the upper limit of the predetermined range, the peak intensity of the signal light emitted from the signal light source 3 is small. Thus, the signal light source 3 is controlled. Specifically, the intensity of the excitation light emitted from the excitation light source 11 is reduced. When the pulse width of the monitor light measured by the measurement unit 32 is larger than the upper limit of the predetermined range, it means that the pulse width of the signal light emitted from the signal light source 3 is larger than a desired value. When the pulse width of the signal light emitted from the signal light source 3 is larger than a desired value, the pulse width of the laser light emitted from the laser device 1 is also increased. For this reason, the quality of the laser beam may be inferior. In the signal light source 3 of this embodiment, there is also a positive correlation between the peak intensity of the signal light and the pulse width. For this reason, by controlling the signal light source 3 so that the peak intensity of the signal light is reduced as described above, the pulse width of the laser light emitted from the laser device 1 can be reduced. Therefore, the feedback control for reducing the peak intensity of the signal light is repeated until the pulse width of the monitor light is below the upper limit of the predetermined range, so that the pulse width of the laser light emitted from the laser device 1 falls within a desired range. It can be controlled to be below the upper limit. Therefore, the quality of the laser beam can be improved. Thus, by improving the quality of the laser beam, the influence of the pulse width, output, peak intensity, etc. of the laser beam emitted from the laser device 1 due to temperature and disturbance can be reduced. Therefore, when the laser apparatus 1 is used for a processing machine, a stable processing result can be obtained.

  As described above, the signal light source 3 is controlled so that the pulse width of the monitor light measured by the measurement unit 32 falls within a predetermined range, so that signal light having a desired range of intensity is emitted from the signal light source 3. Can be done.

  Further, when the control unit 33 of the present embodiment determines that the pulse width of the monitor light measured by the measurement unit 32 is equal to or less than a specific value smaller than the lower limit of the predetermined range, the excitation light from the excitation light source 21 Control to stop the emission of. In the laser apparatus 1 of the present embodiment, the control unit 33 controls the signal light source 3 so that the pulse width of the monitor light to be measured is not less than the lower limit of the predetermined range as described above, and emits from the signal light source 3. It is possible to control the intensity of the signal light to be equal to or higher than the lower limit of the desired range. Therefore, when the pulse width of the monitor light measured by the measurement unit 32 is not more than a specific value smaller than the lower limit of the predetermined range, the intensity of the signal light emitted from the signal light source 3 is unintentionally reduced. ing. In such a state, the operation of the laser device 1 can be prevented from becoming unstable by stopping the emission of the excitation light from the excitation light source 21 provided in the optical amplifier 4.

  As described above, the laser device 1 indirectly measures the intensity of the signal light based on the pulse width of the monitor light. The pulse width of the monitor light is not easily affected by variations in performance of the optical component 30 and the light receiving unit 31. In the laser apparatus 1, the pulse width of the monitor light is controlled to be in a certain range regardless of variations in performance of the optical component 30 and the light receiving unit 31. Therefore, when the pulse width of the monitor light is measured as described above, variations in measurement results due to variations in performance of the optical component 30 and the light receiving unit 31 can be suppressed as compared with the case where the intensity of the monitor light is measured. Therefore, in the laser apparatus 1, it can suppress that dispersion | variation arises in the measurement result of the intensity | strength of signal light.

(Second Embodiment)
Next, a second embodiment of the present invention will be described in detail with reference to FIG. In addition, about the structure which is the same as that of 1st Embodiment, or equivalent, unless it demonstrates especially, the same referential mark is attached | subjected and the overlapping description is abbreviate | omitted.

  FIG. 3 is a diagram showing a laser apparatus 1a according to the second embodiment of the present invention. As shown in FIG. 3, the laser device 1a of the present embodiment is different from the laser device 1 of the first embodiment in that the wavelength conversion unit 19 and the optical filter 20 are not provided. Therefore, the pulse light source 2 of the present embodiment can be understood as a signal light source. Further, as will be described later, in the laser apparatus 1a of the present embodiment, the control by the control unit 33 is different from the laser apparatus 1 of the first embodiment.

  FIG. 4 is a graph showing the relationship between the pulse width [ns] of the pulsed light emitted from the pulsed light source 2 and the peak voltage [V] of the electrical signal resulting from the peak intensity of the monitor light obtained by the light receiving unit 31. . In the present embodiment, pulsed light emitted from the pulsed light source 2 is signal light. As described in the first embodiment, the pulse width of the pulsed light emitted from the pulsed light source 2 decreases as the peak intensity increases. Therefore, a negative voltage as shown in FIG. 4 is present between the pulse width of the pulsed light emitted from the pulsed light source 2 of the present embodiment and the peak voltage of the electrical signal generated due to the peak intensity of the monitor light. There is a correlation. Thus, the pulse light source 2 of the present embodiment emits signal light whose pulse width decreases as the peak intensity increases. In the laser device 1a, similarly to the laser device 1, the monitor light that is a part of the signal light is branched by the optical component 30, and the pulse width of the monitor light is measured. As described above, there is a positive correlation between the pulse width of the monitor light and the pulse width of the signal light. Therefore, the peak intensity of the signal light can be indirectly measured by measuring the pulse width of the monitor light.

  The control unit 33 according to the present embodiment controls the pulse light source 2 and the optical amplifier 4 as described below.

  When the control unit 33 according to the present embodiment determines that the pulse width of the monitor light measured by the measurement unit 32 is larger than the upper limit of the predetermined range, the peak intensity of the signal light emitted from the pulse light source 2 is increased. The pulse light source 2 is controlled. As described above, there is a correlation between the pulse width of the monitor light and the peak intensity of the signal light, and the pulse width of the monitor light measured by the measurement unit 32 is larger than the upper limit of the predetermined range. It shows that the peak intensity of light is smaller than the lower limit of the desired range. Therefore, the feedback control for increasing the peak intensity of the signal light is repeated until the pulse width of the monitor light measured by the measurement unit 32 is equal to or less than the upper limit of the predetermined range, so that the peak intensity of the signal light is within a desired range. It can be controlled to be equal to or greater than the lower limit of.

  In addition, when the control unit 33 of the present embodiment determines that the pulse width of the monitor light measured by the measurement unit 32 is smaller than the lower limit of the predetermined range, the peak intensity of the signal light emitted from the pulse light source 2 is small. You may control the pulse light source 2 so that it may become. Specifically, the intensity of the excitation light emitted from the excitation light source 11 is reduced. When the pulse width of the monitor light measured by the measurement unit 32 is smaller than the lower limit of the predetermined range, it means that the pulse width of the signal light emitted from the pulse light source 2 is smaller than a desired value. When the pulse width of the signal light emitted from the pulse light source 2 is smaller than a desired value, the pulse width of the laser light emitted from the laser device 1a is also reduced. For this reason, the quality of the laser beam may be inferior. In the pulse light source 2 of the present embodiment, there is a negative correlation between the peak intensity of the signal light and the pulse width. For this reason, by controlling the pulse light source 2 so that the peak intensity of the signal light is reduced as described above, the pulse width of the laser light emitted from the laser device 1a can be increased. Therefore, the feedback control for reducing the peak intensity of the signal light is repeated until the pulse width of the monitor light becomes equal to or greater than the lower limit of the predetermined range, whereby the pulse width of the laser light emitted from the laser device 1a falls within a desired range. It can be controlled to be equal to or higher than the lower limit. Therefore, the quality of the laser beam can be improved. By improving the quality of the laser light in this way, the influence of the pulse width, output, peak intensity, etc. of the laser light emitted from the laser device 1a due to temperature and disturbance can be reduced. Therefore, when the laser apparatus 1a is used for a processing machine, a stable processing result can be obtained.

  As described above, the signal light source 3 is controlled so that the pulse width of the monitor light measured by the measurement unit 32 falls within a predetermined range, so that the signal light having the intensity in a desired range is emitted from the pulse light source 2. Can be done.

  In addition, when the control unit 33 according to the present embodiment determines that the pulse width of the monitor light measured by the measurement unit 32 is equal to or greater than a specific value larger than the upper limit of the predetermined range, the excitation light from the excitation light source 21 is used. Control to stop the emission of. In the laser apparatus 1a of the present embodiment, the control unit 33 controls the signal light source 3 so that the pulse width of the monitor light is not more than the upper limit of the predetermined range as described above. Thereby, it can control so that the intensity | strength of the signal light radiate | emitted from the pulse light source 2 may become more than the minimum of a desired range. Therefore, when the pulse width of the monitor light measured by the measurement unit 32 becomes a specific value larger than the upper limit of the predetermined range, the intensity of the signal light emitted from the pulse light source 2 is unintentionally reduced. Yes. In such a state, it is possible to prevent the operation of the laser device 1a from becoming unstable by stopping the emission of the excitation light from the excitation light source 21 provided in the optical amplifier 4.

  As mentioned above, although the said embodiment was demonstrated to the example about this invention, this invention is not limited to these.

  For example, the signal light source is not particularly limited as long as it emits signal light having a correlation between the pulse width and the peak intensity. For example, the signal light source may be a light source having a laser diode (LD) that emits seed light and an amplification optical fiber that amplifies the seed light. In this case, signal light having a negative correlation between the pulse width and the peak intensity can be emitted from the signal light source.

  The control unit only needs to control at least the signal light source, and it is not essential to control the optical amplifier by the control unit. Further, the optical amplifier is not an essential configuration.

  In the above embodiment, the signal light source is controlled by the control unit so that the pulse width of the monitor light measured by the measurement unit falls within a predetermined range. However, the present invention is limited to this mode. Not. What is necessary is just to be controlled by a control part so that the intensity | strength of the signal light radiate | emitted from a signal light source may become more than predetermined value at least. Therefore, for example, in the laser device 1 according to the first embodiment, the control unit 33 causes the pulse width of the monitor light measured by the measurement unit 32 to be equal to or greater than a predetermined value according to the output from the measurement unit 32. The signal light source 3 may be controlled. Further, in the laser apparatus 1a of the second embodiment, the control unit 33 is configured to generate a pulse light source so that the pulse width of the monitor light measured by the measurement unit 32 is equal to or less than a predetermined value according to the output from the measurement unit 32. 2 may be controlled.

  As described above, according to the present invention, there is provided a laser device capable of suppressing variations in the measurement result of signal light intensity, and can be used in a field using laser light such as a processing machine or a medical device. Be expected.

DESCRIPTION OF SYMBOLS 1, 1a ... Laser apparatus 2 ... Pulse light source 3 ... Signal light source 4 ... Optical amplifier 11, 21 ... Excitation light source 12, 22 ... Amplifying optical fiber 18 ... Q switch DESCRIPTION OF SYMBOLS 19 ... Wavelength conversion unit 20 ... Optical filter 30 ... Optical component 31 ... Light receiving part 32 ... Measuring part 33 ... Control part

Claims (5)

A signal light source that emits signal light whose pulse width increases as the peak intensity increases;
An optical component for branching the monitor light which is a part of the signal light;
A light receiving unit for receiving the monitor light branched by the optical component;
A measurement unit for measuring the pulse width of the monitor light based on an output from the light receiving unit;
A control unit that controls the signal light source so that a pulse width of the monitor light measured by the measurement unit is equal to or greater than a predetermined value in response to an output from the measurement unit;
A laser device comprising: An optical amplifier further comprising: an amplification optical fiber that amplifies the signal light; and an excitation light source that emits excitation light incident on the amplification optical fiber.
The control unit stops emission of the excitation light from the excitation light source when a pulse width of the monitor light measured by the measurement unit becomes equal to or less than a specific value smaller than the predetermined value. The laser device according to claim 1. A signal light source that emits signal light whose pulse width decreases as the peak intensity increases;
An optical component for branching the monitor light which is a part of the signal light;
A light receiving unit for receiving the monitor light branched by the optical component;
A measurement unit for measuring the pulse width of the monitor light based on an output from the light receiving unit;
A control unit for controlling the signal light source so that a pulse width of the monitor light measured by the measurement unit is equal to or less than a predetermined value in accordance with an output from the measurement unit;
A laser device comprising: An optical amplifier further comprising: an amplification optical fiber that amplifies the signal light; and an excitation light source that emits excitation light incident on the amplification optical fiber.
The control unit stops emission of the excitation light from the excitation light source when a pulse width of the monitor light measured by the measurement unit becomes equal to or larger than a specific value larger than the predetermined value. The laser device according to claim 3. 5. The control unit according to claim 1, wherein the control unit controls the signal light source so that a pulse width of the monitor light measured by the measurement unit falls within a predetermined range. 6. Laser device.

Images