Laser Equipment

Abstract

The laser device includes a laser resonator (100) having a laser medium (30) that absorbs excitation light (11) and emits oscillating light (101), an optical length adjustment unit (40) that adjusts the optical length of the laser resonator (100), and a control unit (60) that transmits a control signal (61) to the optical length adjustment unit (40) synchronized with the oscillation timing of the oscillating light emitted from the laser resonator (100).

Description

[Technical field]

[0001] The present disclosure relates to a laser device. [Background technology]

[0002] A microchip laser disclosed in Non-Patent Document 1 is a small-sized pulse laser capable of outputting high peak power. This microchip laser eliminates unnecessary components and spaces from within the resonator by applying a coating directly to the laser crystal. Therefore, the microchip laser can output a short pulse by shortening the optical length of the laser resonator, and as a result, a laser pulse with high peak power can be obtained.

[0003] To obtain a short pulse, it is important to shorten the optical length of the laser resonator. Laser resonators have a parameter called the resonator lifetime, which is the length of time that the light in the resonator is maintained when the supply of light is stopped. For this reason, in principle, a laser resonator cannot output a laser pulse shorter than the resonator lifetime. In this case, mode-locked lasers are excluded.

[0004] Resonator life τ c is the time τ required for light to travel around the laser cavity once, assuming a Fabry-Perot type laser cavity. r Using the reflectances R1 and R2 of the two mirrors that make up the laser resonator, the time τ r becomes longer, and the resonator life τ c In other words, in order to obtain a short pulse, the resonator lifetime τ c It is important to shorten the optical length of the laser resonator. τ c =-τ r / ln(R1 R2) (1)

[0005] Pulse lasers generally use an element called a Q switch. This Q switch is an element that can change the Q value, which indicates the strength of confinement in the laser resonator. If the Q value of the laser resonator is low, it becomes difficult for the laser resonator to oscillate, and energy accumulates in the laser medium. After a sufficient amount of energy has accumulated in the laser medium, the Q value of the laser resonator can be increased to satisfy the conditions for laser oscillation, and the energy stored in the laser medium is released all at once. This allows pulse lasers to emit pulsed laser light.

[0006] In microchip lasers, an element called a passive Q-switch is often used to shorten the optical length of the laser resonator. A passive Q-switch is an element with saturable absorption characteristics, such as a saturable absorbing mirror made of Cr:YAG crystal or semiconductor. Saturable absorption characteristics are the property of an element's absorption of photons decreasing when it absorbs photons. In a laser resonator with a built-in passive Q-switch with saturable absorption characteristics, when the spontaneous emission light emitted by energy stored in the laser medium reaches a certain level of intensity, the absorption rate of the passive Q-switch decreases significantly. Therefore, the microchip laser satisfies the laser oscillation conditions and can emit a pulsed laser.

[0007] A microchip laser using a passive Q switch has a problem that it is difficult to oscillate a pulse at a targeted timing because the pulse energy is determined by the design. This is because the conditions under which a passive Q switch operates are determined by physical properties. For example, when the excitation light is strengthened, the pulse energy increases in a general Q switch. In contrast, in a passive Q switch laser, the pulse energy does not change, but the repetition frequency increases. For this reason, Patent Document 1 discloses a method of monitoring a part of the output pulse, adjusting the excitation light intensity, and controlling the timing. [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] H. Sakai et al., “>1 MW peak power single-mode high-brightness passively Q-switched Nd3+: YAG microchip laser,” Opt. Express 16, 19891-19899 (2008). [Patent documents]

[0009] [Patent Document 1] Patent Publication No. 2012-142523 Summary of the Invention [Problem to be solved by the invention]

[0010] The passively Q-switched laser device disclosed in Patent Document 1 is based on the premise of repeated pulses, and cannot oscillate pulses at a perfectly targeted timing. In addition, the passively Q-switched laser device disclosed in Patent Document 1 cannot control the pulse energy.

[0011] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a laser device that can oscillate a laser pulse at any timing and can independently control the pulse energy and the pulse oscillation timing. [Means for solving the problem]

[0012] The laser device according to the present disclosure includes a laser resonator having a laser medium that absorbs excitation light and emits oscillation light, an optical length adjustment unit that adjusts the optical length of the laser resonator, and a control unit that transmits a control signal to the optical length adjustment unit that is synchronized with the oscillation timing of the oscillation light emitted from the laser resonator. The optical length of the laser resonator is the optical length at which the interval of the wavelengths that satisfy the standing wave condition based on the optical length is wider than the width of the stimulated emission cross section of the laser medium. . Effect of the Invention

[0013] According to the present disclosure, it is possible to oscillate a laser pulse at any timing, and it is possible to control the pulse energy and the pulse oscillation timing independently. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram showing a configuration of a laser device according to a first embodiment. [Diagram 2] 4 is a schematic diagram showing another configuration of the laser device according to the first embodiment. FIG. [Diagram 3] FIG. 1 is a diagram showing the relationship between the round-trip optical length of a laser resonator and the standing wave wavelength interval. [Figure 4] FIG. 2 is a diagram showing the relationship between the round-trip optical length of a laser resonator and the oscillation wavelength. [Diagram 5] FIG. 11 is a schematic diagram showing the configuration of a laser device according to a second embodiment. [Figure 6] 6A and 6B are diagrams showing the change in the optical length of a laser cavity over time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] In order to describe the present disclosure in more detail, embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0016] Embodiment 1 A laser device according to a first embodiment will be described with reference to FIGS. 1 to 4. FIG.

[0017] 1 is a schematic configuration diagram of a laser device according to embodiment 1. As shown in FIG. 1, the laser device according to embodiment 1 includes an excitation light source 10, a control unit 60, and a laser resonator 100.

[0018] The excitation light source 10 emits excitation light 11 toward the laser resonator 100. The laser resonator 100 converts the energy of the emitted excitation light 11 into oscillation light 101, and emits the converted oscillation light 101.

[0019] The laser resonator 100 has a first mirror 20, a laser medium 30, an optical length adjusting unit 40, and a second mirror 50. The first mirror 20 is disposed on the incident side of the excitation light 11. The second mirror 50 is disposed on the emission side of the oscillation light 101. The first mirror 20, the laser medium 30, and the second mirror 50 are provided on the optical path of the laser resonator 100.

[0020] The laser medium 30 and the optical length adjustment unit 40 are provided between the first mirror 20 and the second mirror 50. The laser medium 30 is disposed on the first mirror 20 side, and the optical length adjustment unit 40 is disposed on the second mirror 50 side. Note that, as long as the laser medium 30 and the optical length adjustment unit 40 are disposed between the first mirror 20 and the second mirror 50, their installation positions can be adjusted as appropriate. The optical length adjustment unit 40 adjusts the optical length between the first mirror 20 and the second mirror 50.

[0021] The control unit 60 controls the optical length adjustment unit 40 in synchronization with the period or oscillation timing of the laser pulse in the oscillating light 101 emitted from the laser resonator 100 by transmitting a control signal 61 to the optical length adjustment unit 40.

[0022] The excitation light 11 is light having a wavelength that is absorbed by the laser medium 30. When the absorption spectrum of the laser medium 30 is narrow, the temperature of the excitation light source 10 may be adjusted to stabilize the wavelength of the excitation light 11. The excitation light 11 may be continuous light or pulsed light. In the case of pulsed light, a control signal 61 from a control unit 60 may be sent to the excitation light source 10 to control the pulse oscillation timing. Furthermore, the excitation light 11 may be emitted directly from the excitation light source 10 to the first mirror 20, may pass through an optical fiber, or may pass through an optical element such as a lens.

[0023] The first mirror 20 is provided between the excitation light source 10 and the laser medium 30. The first mirror 20 has a high reflection function for the oscillation wavelength and an anti-reflection function for the excitation wavelength. The first mirror 20 is formed of, for example, a dielectric multilayer film. The first mirror 20 may be coated on the surface of the laser medium 30, or may be attached to a separate glass substrate (not shown). The first mirror 20 has a high transmittance for the excitation light 11 and a high reflectance for the oscillation light 101. In reality, it is difficult to achieve 100% transmittance or 100% reflectance in the first mirror 20, but the first mirror 20 designed to have the highest possible transmittance or reflectance is called a high transmittance or high reflectance. In reality, it refers to 99% or more.

[0024] The laser medium 30 is capable of absorbing the pumping light 11 and emitting or amplifying light having the wavelength of the oscillation light 101. The laser medium 30 may be, for example, Nd 3+ Ion-doped Yttrium Aluminum Garnet (YAG) or YVO 4 , Fluorapatite (FAP) crystal or ceramic, Yb 3+ Similar crystals or ceramics doped with ions, Er 3+ Similar crystals or ceramics, glasses, etc. with added ions may be used.

[0025] The second mirror 50 is provided on the opposite side of the first mirror 20 with respect to the laser medium 30 and the optical length adjustment unit 40. The second mirror 50 has a partial reflection function with a predetermined reflectance with respect to the oscillation wavelength. The second mirror 50 is formed of, for example, a dielectric multilayer film. The second mirror 50 may be coated on the surface of the laser medium 30, or may be attached to a separate glass substrate (not shown). The second mirror 50 has a partial reflectance with respect to the oscillation light 101. If the absorption rate of the laser medium 30 with respect to the excitation light 11 is not sufficient, it is desirable that the second mirror 50 has a high reflectance and makes the excitation light 11 go back and forth to increase the absorption rate. Also, if the absorption rate of the laser medium 30 with respect to the excitation light 11 is sufficient, the second mirror 50 may have any reflectance with respect to the excitation light 11.

[0026] When the absorption rate of the laser medium 30 is insufficient even if the excitation light 11 is made to go back and forth using the highly reflective second mirror 50 for the excitation light 11, the laser device according to the first embodiment resonates the excitation light 11 and makes it go back and forth through the laser medium 30 multiple times. Therefore, the laser device according to the first embodiment can increase the absorption of the excitation light 11 in the laser medium 30. In this case, when the excitation light 11 emitted from the excitation light source 10 is partially reflected by the second mirror 50 and travels toward the excitation light source 10, the second mirror 50 is arranged perpendicular to the optical axis of the excitation light 11 so that the optical axis does not shift. Therefore, the excitation light 11 that is not absorbed by the laser medium 30 returns to the excitation light source 10.

[0027] The excitation light 11 is reflected by the end face of the excitation light source 10, or recombines inside the excitation light source 10 and is emitted again toward the laser medium 30. Therefore, the laser device according to the first embodiment can cause the excitation light 11 to be sufficiently absorbed by the laser medium 30 by passing the excitation light 11 through the laser medium 30 multiple times. When the reflected light of the excitation light 11 is recombined inside the excitation light source 10, this is called intracavity excitation, and even if the absorption rate of the laser medium 30 is low, the laser medium 30 can be excited with high efficiency. In the laser device according to the first embodiment, a thin laser medium 30 is used, so intracavity excitation is effective.

[0028] The laser resonator 100 includes a laser medium 30 between a first mirror 20 and a second mirror 50. The optical length adjustment unit 40 adjusts the optical length of the laser resonator 100, i.e., the optical length between the first mirror 20 and the second mirror 50. The optical length is the time it takes for light to travel multiplied by the speed of light in a vacuum, and is calculated by multiplying the actual length by the refractive index of light.

[0029] Therefore, the optical length adjustment unit 40 may be one that can adjust the actual length, or may be a mechanism that can change the refractive index. Examples of the optical length adjustment unit 40 include an electro-optical element (EO element), a magneto-optical element (MO element), a temperature control element, a piezoelectric element, and a MEMS.

[0030] When using an optical length adjusting section 40 that adjusts the optical length of the laser resonator 100 using a refractive index like an electro-optical element, the optical length adjusting section 40 is disposed inside the laser resonator 100 as shown in FIG.

[0031] 2 is a schematic diagram showing another configuration of the laser device according to the first embodiment. When an optical length adjustment unit 40 that adjusts the length of the laser resonator 100 by a physical length, such as a piezoelectric element, is used and the optical length adjustment unit 40 is opaque to the oscillation light 101, the optical length adjustment unit 40 is disposed outside the laser resonator 100 as shown in FIG. 2. When the optical length adjustment unit 40 utilizes thermal expansion due to temperature or the temperature dependency of the refractive index, the optical length adjustment unit 40 is a heater or a Peltier element and is disposed outside the laser resonator 100. In this case, the optical length adjustment unit 40 controls the length of the laser resonator 100 by adjusting the temperature of the laser medium 30.

[0032] As shown in FIG. 2, when the optical length adjustment unit 40 is a piezoelectric element, the second mirror 50 or its holder extends to the outside of the laser resonator 100, and the optical length adjustment unit 40 is provided on the extended portion.

[0033] Here, the laser resonator 100 has a standing wave condition based on the optical length, and light other than the wavelength λ that satisfies this condition cannot be efficiently accumulated. c Let m be an arbitrary integer, and the wavelength λ that satisfies the standing wave condition is m can be expressed by the following formula (2). Note that the wavelength refers to the wavelength in a vacuum. 2L c =mλ m (2)

[0034] As is clear from equation (2), the wavelength λ that satisfies the standing wave condition m The distance between the laser resonator 100 and the optical length L c The smaller the frequency, the wider the interval. This interval is called the Free Spectral Range (FSR), and is a constant interval in the frequency domain. This frequency interval ν FSR can be expressed by the following formula (3). Note that there is a relationship between the wavelength λ and the frequency ν: λ=c / ν. ν FSR =c / 2L c (3)

[0035] On the other hand, among the laser media 30, for example, Nd 3+ Y with added ions 3 AI 5 O 12 Nd:YAG is known to have a narrow spectrum width of stimulated emission. According to Non-Patent Document 2, the peak width of 1064 nm used in Nd:YAG is 1.1 nm. The laser medium 30 may be an Nd:YAG crystal or any laser medium with a narrow spectrum width of stimulated emission. For example, according to Non-Patent Document 2, Nd:YVO 4 The Nd:FAP has a peak width of 0.6 nm, similar to the Nd:YAG. 4 Since Nd:FAP has birefringence, it can produce linearly polarized laser output, and is therefore suitable for situations where a linearly polarized output is desired.

[0036] [Non-Patent Document 2] T. Taira, “RE3+-Ion-Doped YAG Ceramic Lasers,” IEEE J. Sel. Top. Quant. Electron. 13, 798 (2007).

[0037] 3 is a diagram showing the relationship between the round-trip optical length of the laser resonator 100 and the standing wave wavelength interval. From equation (2), FIG. 3 shows the wavelength λ 1 that satisfies the standing wave condition around a wavelength of 1064 nm. m 3 shows the relationship between the distance between the laser resonator 100 and the round-trip optical length. The horizontal axis of FIG. 3 shows the round-trip optical length of the laser resonator 100, and the vertical axis of FIG. 3 shows the standing wave wavelength interval. As shown in FIG. 3, when the round-trip length of the laser resonator 100 is 1 mm or less, the wavelength λ 2 that satisfies the standing wave condition becomes m It can be seen that the spacing is 1.1 nm or less.

[0038] 4 is a diagram showing the relationship between the round-trip optical length and the oscillation wavelength of the laser resonator 100. This Fig. 4 shows the relationship between the amount of change when the round-trip optical length is changed by about 1 mm and the wavelength λ that satisfies the standing wave condition. mThe horizontal axis of FIG. 4 indicates the round-trip optical length of the laser resonator 100, and the vertical axis of FIG. 4 indicates the oscillation wavelength. According to Non-Patent Document 2, the peak width of the stimulated emission cross section of Nd:YAG near the wavelength λ 1064 nm is 1064.2 nm, so when the optical length of the resonator is 1.00035 mm, the standing wave condition and the peak width of the stimulated emission cross section exactly match. On the other hand, when the optical length of the resonator is 0.9998 mm, the wavelength λ m Since the standing wave condition is satisfied at 1064.75 nm or 1063.62 nm, the wavelength λ that satisfies the standing wave condition is m However, the wavelength is separated from the peak wavelength of the stimulated emission cross section by 0.55 nm, which is half of 1.1 nm. This results in a large decrease in gain compared to when the optical length of the resonator is 1.00035 mm.

[0039] In the laser device according to the first embodiment, the round-trip optical length of the laser resonator 100 is set to about 1 mm, and the gain is changed greatly by a slight change in the optical length of 0.55 μm (1.00035 mm-0.9998 mm=0.00055 mm). Therefore, the laser device according to the first embodiment can oscillate a laser pulse at any timing. In other words, when the optical length of the laser resonator 100 is set to 0.9998 mm, Hey The wavelength λ that satisfies the standing wave condition is m Since the gain of the light is small, it is possible to store sufficient energy in the Nd:YAG crystal. After storing sufficient energy, the optical length adjustment unit 40 adjusts the optical length of the laser resonator 100 to 1.00035 mm, thereby adjusting the wavelength λ 2 that satisfies the standing wave condition. m The gain of the light increases, and a laser pulse is generated.

[0040] The timing at which the laser pulse is oscillated can be arbitrarily set by the control signal 61 transmitted from the control unit 60 to the optical length adjustment unit 40. The laser device according to the first embodiment can be considered as a gain-switched laser because the gain is changed by the control unit 60 provided outside the laser resonator 100 to oscillate the laser in a pulsed manner. Therefore, the laser device according to the first embodiment can adjust the pulse energy by the intensity of the excitation light 11, although to a certain extent, and can control the pulse energy and the laser pulse oscillation timing independently. Therefore, the control signal 61 transmitted from the control unit 60 becomes a signal that fluctuates in accordance with the laser pulse oscillation timing of the oscillating light 101.

[0041] The optical length of the laser resonator 100 is not limited to 1 mm round trip, but is set to a wavelength λ 1 that satisfies the standing wave condition, which can be calculated using equation (2). m and the peak width of the stimulated emission cross section of the laser medium 30 used. In other words, if the peak width of the laser medium 30 is narrow, the optical length of the laser resonator 100 may be long, and if the peak width of the laser medium 30 is wide, the optical length of the laser resonator 100 needs to be short. Here, it is important to consider the wavelength λ that satisfies the standing wave condition rather than the peak width of the stimulated emission cross section of the laser medium 30. m The optical length of the laser resonator 100 is set so that the interval between the peaks is wide. For example, according to Non-Patent Document 2, the peak width of Nd:FAP is 0.6 nm, and in this case, an optical length of 1.9 mm or less satisfies this condition.

[0042] Generally, the laser medium 30 has a plurality of peak wavelengths in the stimulated emission cross section. The wavelength at which the laser oscillates is determined by the relationship between the gain and the reflectance of the first mirror 20 and the second mirror 50.

[0043] Furthermore, the FSR has a constant interval in the frequency domain, but when converted to wavelength, it has a different wavelength interval at the center wavelength. m The "interval" refers to a wavelength interval in the vicinity of the wavelength of the oscillating light 101.

[0044] As described above, the laser device according to the first embodiment can oscillate a laser pulse at any timing by controlling the optical length of the laser resonator 100. In addition, the laser device according to the first embodiment can greatly change the gain in the laser resonator 100, so that it can store energy in the laser medium 30 in a low gain state and oscillate a laser pulse by transitioning from the low gain state to a high gain state. Furthermore, the laser device according to the first embodiment can adjust the pulse energy to some extent by the intensity of the excitation light 11, so that it can control the pulse energy and the laser pulse oscillation timing independently of each other.

[0045] Embodiment 2 A laser device according to the second embodiment will be described with reference to Fig. 5 and Fig. 6. Note that components having the same functions as those described in the first embodiment above are given the same reference numerals, and the description thereof will be omitted.

[0046] 5 is a schematic diagram showing the configuration of a laser device according to embodiment 2. The laser device according to embodiment 2 includes a laser resonator 200 instead of the laser resonator 100 of the laser device according to embodiment 1. The laser device according to embodiment 2 also includes a measuring device 70 and an optical length correction unit 80 in addition to the laser device according to embodiment 1.

[0047] As shown in FIG. 5, the laser device according to the second embodiment includes an excitation light source 10, an optical length adjusting unit 40, a control unit 60, a measuring device 70, and a laser resonator 200.

[0048] The laser resonator 200 emits an oscillation light 201. The laser resonator 200 includes a first mirror 20, a laser medium 30, a second mirror 50, and an optical length correction unit 80. The laser medium 30 is disposed on the first mirror 20 side. The optical length correction unit 80 is in contact with the laser medium 30. The optical length correction unit 80 is controlled by inputting a control signal 62 from the control unit 60. In this case, when the optical length adjustment unit 40 is a piezoelectric element, the second mirror 50 or its holder extends to the outside of the laser resonator 200, and the optical length adjustment unit 40 is provided on the extended portion.

[0049] The measuring instrument 70 measures the oscillation timing of the laser pulse emitted from the laser resonator 100. The measuring instrument 70 also transmits the measurement result to the control unit 60 as a measurement signal 71. The measuring instrument 70 measures the laser pulse oscillation timing of the oscillating light 201, for example, from the scattered light of the oscillating light 201. The measuring instrument 70 may measure the laser pulse oscillation timing by extracting a part of the oscillating light 201 using a mirror with a reflectance of several percent.

[0050] The control unit 60 controls the optical length adjustment unit 40 and the optical length correction unit 80 in accordance with the measurement results of the measuring device 70.

[0051] The optical length correction unit 80, like the optical length adjustment unit 40, is an EO element, an MO element, a temperature control element, a piezoelectric element, a MEMS, or the like, and adjusts the optical length of the laser resonator 200 by changing the physical length or the refractive index of light.

[0052] However, while the optical length adjusting unit 40 varies the optical length in accordance with the laser pulse oscillation timing of the oscillating light 201, the optical length correcting unit 80 is for correcting the optical length on a longer time scale. Therefore, a mechanism with a relatively slow response speed, such as a temperature control element, is acceptable. For this reason, in the laser device according to the second embodiment, the optical length correcting unit 80 is assumed to be a Peltier element, which is a temperature control element.

[0053] The laser device according to the second embodiment controls the gain by, for example, a change in optical length of 0.5 nm for an optical length of about 1 mm. Therefore, it is conceivable that the operating point may change due to the ambient temperature or aging. If the operating point changes, the timing at which the laser pulse oscillates will deviate from the expected timing. For this reason, the laser device according to the second embodiment compares the measurement signal 71 from the measuring device 70 with an expected laser pulse timing signal in the control unit 60, and transmits a control signal 62 from the control unit 60 to the optical length correction unit 80, which indicates that the deviation in the laser pulse oscillation timing should be corrected.

[0054] FIG. 6 is a diagram showing the change over time in the optical length of the laser resonator 200. The vertical axis of FIG. 6 indicates the optical length of the laser resonator 200. The horizontal axis of FIG. 6 indicates the passage of time. For example, as shown in FIG. 6(A), in a state where the optical length of the laser resonator 200 is controlled and a laser pulse is oscillated, if the optical length becomes longer than the initial design due to the ambient temperature or aging, the laser pulse is oscillated at the timing shown in FIG. 6(B). The arrow in FIG. 6(B) indicates the direction in which the laser pulse oscillation timing is shifted.

[0055] When the optical length of the laser resonator 200 is increased, a laser pulse is oscillated at an earlier timing than expected. When the optical length of the laser resonator 200 is decreased, a laser pulse is oscillated at a later timing than expected. The laser device according to the second embodiment detects such a deviation, and uses the optical length correction unit 80 to control the optical length of the laser resonator 200 to be shortened. When the optical length of the laser resonator 200 becomes shorter than the initial design, the laser device according to the second embodiment can detect this in a similar manner, and uses the optical length correction unit 80 to control the optical length of the laser resonator 200 to be shortened.

[0056] The laser device according to the second embodiment includes the optical length adjustment unit 40 and the optical length correction unit 80 as separate units, but the optical length adjustment unit 40 may have the function of the optical length correction unit 80. In this case, the laser device according to the second embodiment compares the signal from the measuring device 70 with an assumed laser pulse timing signal in the control unit 60, corrects the operating point, and adjusts only the control signal 61.

[0057] As described above, the laser device according to the second embodiment can oscillate a laser pulse at any timing by controlling the optical length of the laser resonator 200.

[0058] In addition, within the scope of the present disclosure, the embodiments may be freely combined, or any of the components in each embodiment may be modified, or any of the components in each embodiment may be omitted. [Industrial Applicability]

[0059] The laser device according to the present disclosure can oscillate a laser pulse at any timing by transmitting a control signal synchronized with the oscillation timing of the oscillating light emitted from the laser resonator to the optical length adjustment unit, and is suitable for use in laser devices and the like that can independently control the pulse energy and the pulse oscillation timing. [Explanation of symbols]

[0060] 10 pumping light source, 11 pumping light, 20 first mirror, 30 laser medium, 40 optical length adjusting section, 50 second mirror, 60 control section, 61, 62 control signal, 70 measuring device, 71 measurement signal, 80 optical length correction section, 100, 200 laser resonator, 101, 201 oscillation light.

Claims

1. a laser resonator having a laser medium that absorbs pumping light and emits oscillating light; an optical length adjustment unit that adjusts the optical length of the laser resonator; a control unit that transmits a control signal to the optical length adjustment unit in synchronization with an oscillation timing of the oscillation light emitted from the laser resonator; The optical length of the laser resonator is such that the interval between wavelengths that satisfy the standing wave condition based on the optical length is wider than the width of the stimulated emission cross-section of the laser medium. A laser device characterized by:

2. a measuring device for measuring the oscillation timing of the oscillating light emitted from the laser resonator; The control unit controls the optical length adjustment unit in response to a measurement result of the measurement device.

2. The laser device according to claim 1.

3. an optical length correction unit that corrects a deviation of an optical length of the laser resonator from a design value; The control unit controls the optical length correction unit in accordance with the measurement result of the measurement device.

3. The laser device according to claim 2.

4. The optical length adjusting unit is provided outside the laser resonator.

3. The laser device according to claim 2.

5. The laser resonator comprises: a first mirror provided on one end side of the laser medium and totally reflecting an oscillating light; a second mirror provided on the other end side of the laser medium for partially reflecting the oscillating light; The pumping light absorbed in the laser medium is partially reflected by the second mirror and recombined with the pumping light source that emits the pumping light, thereby performing intracavity pumping.

2. The laser device according to claim 1.

6. The laser medium is Nd ３＋ Ion-doped YAG or Nd ３＋ Ion-doped YVO ４ and The optical length of the laser resonator is 1 mm or less round trip.

6. The laser device according to claim 1, wherein the laser device is a laser diode.

7. The laser medium is Nd ３＋ Fluorapatite with added ions, The optical length of the laser resonator is 1.9 mm or less.

6. The laser device according to claim 1, wherein the laser device is a laser diode.