Slab-shaped pulse width compression and spectral light amplification device, and femtosecond laser system including same

Abstract

The present disclosure may comprise: a first laser light source; a second laser light source; a diffraction grating for diffracting laser light generated from the first laser light source; a mirror for reflecting the diffracted laser light and transmitting line-shaped laser light generated from the second laser light source; and a slab-shaped crystal doped with a gain medium, which is positioned in an optical path between the diffraction grating and the mirror to amplify and equalize the spectrum of the diffracted laser light and the spectrum of the line-shaped laser light.

Description

SLAP-type pulse width compression and spectral optical amplification device, femtosecond laser system including the same

[0001] The present disclosure relates to a laser system. More specifically, the present disclosure relates to a slab-type pulse width compression and spectral optical amplification device and a femtosecond laser system comprising the same.

[0002] Generally, femtosecond laser light has been used in industrial settings to reduce cutting defects in semiconductor wafers and secondary battery electrodes.

[0003] Here, the femtosecond laser light was modulated into a laser light having a high-energy pulse train, as well as having a repetition rate controlled by a pulse control signal.

[0004] For example, laser light could be generated by a femtosecond fiber laser system.

[0005] However, conventional femtosecond fiber laser systems could not efficiently amplify laser light because they could not make the spectrum of the laser light uniform when amplifying the spectrum of the laser light.

[0006] Therefore, recently, there is a demand for the development of improved technology that can efficiently amplify laser light by making the laser light spectrum uniform.

[0007] The purpose of the embodiment according to the present disclosure is to provide a method for efficiently amplifying and compressing laser light by making the spectrum of the laser light uniform.

[0008] In addition, the embodiment according to the present disclosure is intended to provide a higher gain of laser light by amplifying laser light branched by wavelength.

[0009] In addition, the embodiment according to the present disclosure is intended to provide a way to reduce the pulse width of the final laser light by controlling the spectrum to a uniform state.

[0010] The problems that this disclosure aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by a person skilled in the art from the description below.

[0011] A slab-shaped pulse width compression device according to one aspect of the present disclosure for achieving the above-described technical problem may include: a first laser light source; a second laser light source; a diffraction grating that diffracts laser light generated from the first laser light source; a mirror that reflects the diffracted laser light and transmits line-shaped laser light generated from the second laser light source; and a crystal doped with a slab-shaped gain medium positioned in the optical path between the diffraction grating and the mirror, which amplifies and uniformly amplifies the spectrum of the diffracted laser light and amplifies and uniformly amplifies the spectrum of the line-shaped laser light.

[0012] Additionally, it may further include at least one lens provided on the optical path of the mirror and the second laser light source and focusing the line-shaped laser light.

[0013] Additionally, it may further include an attenuator provided on the optical path of the mirror and the third lens and attenuating the intensity of the line-shaped laser light.

[0014] In addition, the reflection bandwidth of the mirror may be equal to or greater than the bandwidth of the diffracted laser light.

[0015] In addition, it further includes a third laser light source and a fourth laser light source arranged opposite each other to the crystal, and can be pumped in both directions through line-shaped laser light generated from the third laser light source and the fourth laser light source.

[0016] Additionally, it may further include at least one lens provided on the optical path of the third laser light source and the fourth laser light source, and focusing the line-shaped laser light.

[0017] In addition, the reflectance of the mirror is controlled by an external device, and the reflectance can be set differently depending on the wavelength distribution of the diffracted laser light.

[0018] In addition, the crystal can amplify laser light branched by wavelength.

[0019] In addition, the intensity of the above-mentioned line-shaped laser light can be attenuated by an external device.

[0020] In addition, a femtosecond fiber laser system including a slab-type pulse width compression device according to another aspect of the present disclosure may be provided.

[0021] According to the above-described means for solving the problem of the present disclosure, the effect of efficiently amplifying and compressing laser light by making the spectrum of laser light uniform is provided.

[0022] In addition, according to the above-described means for solving the problem of the present disclosure, laser light branched by wavelength can be amplified, thereby providing the effect of obtaining a higher gain of laser light.

[0023] In addition, according to the above-described means for solving the problem of the present disclosure, the spectrum can be adjusted to a uniform state, thereby providing the effect of reducing the pulse width of the final laser light.

[0024] FIG. 1 is a diagram showing a femtosecond fiber laser system according to the present disclosure.

[0025] Figure 2 is a diagram showing an example of the detailed configuration of the femtosecond fiber laser system of Figure 1.

[0026] Figure 3 is a diagram showing the wavelength of the pulsed laser light of Figure 2, the wavelength of the first continuous wave laser light, and the wavelength of the second continuous wave laser light.

[0027] FIGS. 4 to 7 are drawings showing an example of the configuration of a slab-type pulse width compression device of FIG. 2.

[0028] Throughout this disclosure, the same reference numerals denote the same components. This disclosure does not describe all elements of the embodiments, and general content in the art to which this disclosure pertains or content that overlaps between embodiments is omitted. The terms 'part, module, component, block' as used in the specification may be implemented in software or hardware, and depending on the embodiments, a plurality of 'parts, modules, components, blocks' may be implemented as a single component, or a single 'part, module, component, block' may include a plurality of components.

[0029] Throughout the specification, when a part is described as being "connected" to another part, this includes not only cases where they are directly connected but also cases where they are indirectly connected, and indirect connections include connections made via a wireless communication network.

[0030] Furthermore, when it is stated that a part "includes" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0031] Throughout the specification, when it is stated that a component is located "on" another component, this includes not only cases where a component is in contact with another component, but also cases where another component exists between the two components.

[0032] Terms such as "first," "second," etc., are used to distinguish one component from another, and the components are not limited by the aforementioned terms.

[0033] Singular expressions include plural expressions unless there is an obvious exception in the context.

[0034] In each step, identification codes are used for convenience of explanation and do not describe the order of the steps; the steps may be performed differently from the specified order unless a specific order is clearly indicated in the context.

[0035] The operating principles and embodiments of the present disclosure will be described below with reference to the attached drawings.

[0036] FIG. 1 is a drawing showing a femtosecond fiber laser system according to the present disclosure. FIG. 2 is a drawing showing a detailed configuration of the femtosecond fiber laser system of FIG. 1 as an example.

[0037] Figure 3 is a diagram showing the wavelength of the pulsed laser light of Figure 2, the wavelength of the first continuous wave laser light, and the wavelength of the second continuous wave laser light.

[0038] Referring to FIGS. 1 to 3, a femtosecond fiber laser system (100) according to the present disclosure may include a femtosecond light source (10), a preamplifier (20), a pulse picker (30), a first continuous wave light source (40), a main amplifier (50), a slab-type pulse width compression device (60), a polarizing plate (65), a control module (70), and a second continuous wave light source (80).

[0039] The femtosecond light source (10) can generate femtosecond laser light (12). Here, the femtosecond laser light (12) can have a frequency of about 10 MHz to about 1000 MHz.

[0040] A preamplifier (20) can be connected to a femtosecond light source (10). Here, the preamplifier (20) can amplify femtosecond laser light (12).

[0041] The pulse speaker (30) can be connected to a preamplifier (20). Here, the pulse speaker (30) can generate pulsed laser light (32) by modulating femtosecond laser light (12). Here, pulsed laser light (32) refers to femtosecond laser light having any pulse train.

[0042] The first continuous wave light source (40) may be connected to a pulse speaker (30) and a main amplifier (50) by an optical fiber (11). Here, the first continuous wave light source (40) may provide a first continuous wave laser light (42) to the main amplifier (50). For example, the first continuous wave light source (40) may include a laser diode, but the present disclosure is not limited thereto.

[0043] Here, the first continuous wave light source (40) may include a first pump light source (41) and a first ring resonator (43). Here, the first pump light source (41) may generate a first pump light (45). For example, the first pump light source (41) may include a laser diode. Additionally, the first ring resonator (43) may be provided between the first pump light source (41) and the coupler (44). Here, the first ring resonator (43) may have a first radius (R1). Here, the first ring resonator (43) may generate a first continuous wave laser light (42).

[0044] The second continuous wave light source (80) can be connected to the coupler (44). Here, the second continuous wave light source (80) can generate a second continuous wave laser light (82) that is longer than the wavelength of the first continuous wave laser light (42) of the first continuous wave light source (40). Here, the second continuous wave light source (80) may include a second pump light source (81) and a second ring resonator (83). Here, the second pump light source (81) may generate a second pump light (85). For example, the second pump light source (81) may include a laser diode. Additionally, the second ring resonator (83) may be provided between the second pump light source (81) and the coupler (44). Here, the second ring resonator (83) may have a second radius (R2) that is larger than the first radius (R1). Here, the second ring resonator (83) can generate the second continuous wave laser light (82).

[0045] The first continuous wave laser light (42) and the second continuous wave laser light (82) can prevent damage to the main amplifier (50) during the idle period when the pulsed laser light (32) is not in use. In this case, the first continuous wave laser light (42) and the second continuous wave laser light (82) can prevent damage to the main amplifier (50) because, at the moment when the pulsed laser light (32) is turned off, the first pump light source (40) and the second pump light source (80) are turned on, and the first continuous wave laser light (42) and the second continuous wave laser light (82) are oscillated and input to the main amplifier (50).

[0046] Additionally, the first continuous wave laser light (42) and the second continuous wave laser light (82) may have the same polarization. Here, the pulsed laser light (32) may have polarization perpendicular to the first continuous wave laser light (42) and the second continuous wave laser light (82).

[0047] As illustrated in FIG. 3, the wavelength peak of the first continuous wave laser light (42) may overlap with one side of the wavelength band of the pulsed laser light (32), and the wavelength peak of the second continuous wave laser light (82) may overlap with the other side of the wavelength band of the pulsed laser light (32). For example, the wavelength peak of the first continuous wave laser light (42) may overlap with the short wavelength of the pulsed laser light (32), and the wavelength peak of the second continuous wave laser light (82) may overlap with the long wavelength of the pulsed laser light (32). Additionally, the wavelength peak of the first continuous wave laser light (42) may overlap with or touch either end of the wavelength band of the pulsed laser light (32).

[0048] A polarizing plate (65) is provided between the main amplifier (50) and the slab-type pulse width compression device (60) and can remove the first continuous wave laser light (42) and the second continuous wave laser light (82). In one example, a first continuous wave light source (40) provided perpendicular to the polarization axis of the pulsed laser light (32) generates the first continuous wave laser light (42) polarized in one direction, and the polarizing plate (65) can remove the first continuous wave laser light (42). In another example, a second continuous wave light source (80) provided perpendicular to the polarization axis of the pulsed laser light (32) generates the second continuous wave laser light (82) polarized in one direction, and the polarizing plate (65) can remove the second continuous wave laser light (82).

[0049] Here, the polarizing plate (65) may have a polarizer perpendicular to the polarization direction of the first continuous wave laser light (42) and the second continuous wave laser light (82). For example, if the first continuous wave laser light (42) and the second continuous wave laser light (82) are polarized in a horizontal direction, the polarizing plate (65) may have a vertical polarizer. For another example, if the first continuous wave laser light (42) and the second continuous wave laser light (82) are polarized in a vertical direction, the polarizing plate (65) may have a horizontal polarizer.

[0050] The control module (70) may include a memory that stores data for an algorithm or a program that reproduces the algorithm for controlling the operation of components within the system, and at least one processor that performs the aforementioned operation using the data stored in the memory. Here, the memory and the processor may each be provided as separate chips. Additionally, the memory and the processor may be provided as a single chip.

[0051] The memory can store data supporting various functions of the system and programs for the operation of the control module, as well as input or output data. Additionally, the memory can store multiple application programs (or applications) running on the system, data for the operation of the system, and instructions. At least some of these application programs may be downloaded from an external server via wireless communication.

[0052] Here, the memory may include at least one storage medium among Flash Memory type, Hard Disk type, Solid State Disk (SSD) type, Silicon Disk Drive (SSD) type, Multimedia Card Micro type, card type memory (e.g., SD or XD memory, etc.), Random Access Memory (RAM), Static Random Access Memory (SRAM), Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), Programmable Read Only Memory (PROM), magnetic memory, magnetic disk, and optical disk. Additionally, the memory may be a database that is separated from the system and connected via wired or wireless connection.

[0053] Memory can store data related to the femtosecond fiber laser. The processor can control operations related to the femtosecond fiber laser.

[0054] The control module (70) can control the pre-amplifier (20), the pulse speaker (30), and the main amplifier (50). Additionally, the control module (70) can control the pre-amplifier (20) and the pulse speaker (30) to control the generation of femtosecond laser light (12) and pulse laser light (32). Here, when femtosecond laser light (12) and pulse laser light (32) are not generated, the first continuous wave light source (40) can provide the first continuous wave laser light (42) to the main amplifier (50) to prevent burning and damage to the main amplifier (50).

[0055] The femtosecond fiber laser system (100) according to the present disclosure may further include a pulse width expander (15), an isolator (16), a picker control module (34), and a coupler (44).

[0056] A pulse width expander (15) may be provided between the femtosecond light source (10) and the preamplifier (20). Such a pulse width expander (15) can expand the pulse width of the femtosecond laser light (12).

[0057] For example, the pulse width expander (15) may include a circulator (13) and a chirped fiber Bragg diffraction grating (14). Here, the circulator (13) may be provided between the femtosecond light source (10) and the preamplifier (20). Here, the circulator (13) may include at least one port. Additionally, the chirped fiber Bragg diffraction grating (14) may be connected to a port of the circulator (13). Such a chirped fiber Bragg diffraction grating (14) can expand the pulse width of the femtosecond laser light (12).

[0058] The isolator (16) may be connected by an optical fiber (11) between the preamplifier (20) and the pulse picker (30). Such an isolator (16) can protect the preamplifier (20) and the femtosecond light source (10) by blocking the return of the femtosecond laser light (12). Here, the optical fiber (11) located between the preamplifier (20) and the isolator (16) may include a gain medium optical fiber, such as a Yb-doped, Nd-doped, or Er-doped Polarization Maintaining Fiber. For example, the preamplifier (20) may include a laser diode.

[0059] A picker control module (34) can be connected to a pulse picker (30). Such a picker control module (34) can control the pulse repetition rate and the pulse train. Here, an optical fiber coupling device (18) may be provided in the optical fiber (11) adjacent to the picker control unit (34).

[0060] Here, the picker control module (34) provides a pulse control signal to the pulse picker (30), and the pulse picker (30) can generate a pulse laser light (32) by modulating the femtosecond laser light (12) based on the pulse control signal. Here, the pulse control signal and the pulse laser light (32) may have a modulated frequency between about 0 Hz and about 1 GHz.

[0061] A coupler (44) may be provided between a pulse speaker (30) and a main amplifier (50). Additionally, a coupler (44) may be provided between a first continuous wave light source (40) and a main amplifier (50). Here, the coupler (44) may connect the pulse speaker (30) and the first continuous wave light source (40) to the main amplifier (50). For example, the coupler (44) may include a Y-branch coupler.

[0062] Additionally, the coupler (44) can couple optical fibers (11) connected to the first continuous wave light source (40) and the pulse speaker (30). Here, the optical fibers (11) may include single-mode optical fibers. Additionally, the optical fibers (11) may include multi-mode optical fibers, and the present disclosure is not limited thereto.

[0063] A main amplifier (50) may be provided between a pulse speaker (30) and a slab-type pulse width compression device (60). Here, the main amplifier (50) may be provided between a first continuous wave light source (40) and a slab-type pulse width compression device (60). Here, the main amplifier (50) may amplify pulsed laser light (32). Additionally, the main amplifier (50) may amplify the first continuous wave laser light (42). Additionally, the main amplifier (50) may amplify the second continuous wave laser light (82). For example, the main amplifier (50) may include a plurality of laser diodes. Here, the main amplifier (50) may include a first main amplifier (52), a second main amplifier (54), and a third main amplifier (56).

[0064] The first main amplifier (52) may be connected to the coupler (44) and the second main amplifier (54) via an optical fiber (11). Here, the first main amplifier (52) may include a laser diode and a gain medium optical fiber. Here, the gain medium optical fiber of the first main amplifier (52) may include a Yb-doped, Nd-doped, or Er-doped Polarization-Maintaining Fiber. Additionally, the first filter (51) may be connected to the first main amplifier (52) and the second main amplifier (54) via an optical fiber (11). Here, the first filter (51) may remove noise from the pulsed laser light (32) amplified by the first main amplifier (52). Additionally, an isolator (16) may be provided between the first filter (51) and the gain medium optical fiber. Here, the isolator (16) can increase the amplification efficiency of the first main amplifier (52) by blocking reverse flow for the pulsed laser light (32) and the first continuous wave laser light (42).

[0065] The second main amplifier (54) may be connected by an optical fiber (11) between the first main amplifier (52) and the third main amplifier (56). Here, the second main amplifier (54) may include a laser diode and a gain medium optical fiber. Here, the gain medium optical fiber of the second main amplifier (54) may include a Yb-doped, Nd-doped, or Er-doped Polarization-Maintaining Fiber. Additionally, the second filter (53) may be connected by an optical fiber (11) between the second main amplifier (54) and the third main amplifiers (56). Here, the second filter (53) may remove noise from the pulsed laser light (32) amplified by the second main amplifier (54). Additionally, the first cladding mode stripper (55) may be provided between the gain medium optical fiber of the second main amplifier (54) and the second filter (53). Here, the first cladding mode stripper (55) can remove residual pumps within the cladding of the gain medium optical fiber. Additionally, an isolator (16) can be provided between the first cladding mode stripper (55) and the second filter (53). Here, the isolator (16) can increase the amplification efficiency of the second main amplifier (54) by blocking reverse flow for the pulsed laser light (32) and the first continuous wave laser light (42).

[0066] The third main amplifier (56) may be connected via an optical fiber (11) between the second main amplifier (54) and the slab-type pulse width compression device (60). Here, the third main amplifier (56) may include a laser diode and a gain medium optical fiber. Here, the gain medium optical fiber provided between the third main amplifier (56) and the lens (58) may include a Yb-doped, Nd-doped, or Er-doped Polarization-Maintaining Fiber. Additionally, an end cap (59) may be provided at the end of the gain medium optical fiber. Here, the end cap (59) may prevent the end of the optical fiber (11) from being damaged by the amplified pulsed laser light (32) and the first continuous wave laser light (42). Additionally, the lens (58) may be provided between the third main amplifier (56) and the slab-type pulse width compression device (60). Here, the lens (58) can collimate the pulsed laser light (32) and the first continuous wave laser light (42) to the pulse width compression device (60).

[0067] A slab-shaped pulse width compression device (60) can be connected to a main amplifier (50). Here, the slab-shaped pulse width compression device (60) can compress the pulse width of the pulse laser light (32) and block or remove the first continuous wave laser light (42) and the second continuous wave laser light (82).

[0068] FIGS. 4 to 7 are drawings showing an example of the configuration of a slab-type pulse width compression device of FIG. 2.

[0069] Referring to FIGS. 4 to 6, a slab-shaped pulse width compression device (60) may include a first laser light source (LR1), a second laser light source (LR2), a diffraction grating (62, 64), a mirror (66), and a crystal (67).

[0070] An output mirror (61) may be provided between the lens (58) of the main amplifier (50) and the first diffraction grating (62). In this case, the output mirror (61) may be positioned below the pulsed laser light (32). As a result, the pulsed laser light (32) can be transmitted directly to the first diffraction grating (62) regardless of the output mirror (61).

[0071] A first diffraction grating (62) may be provided between an output mirror (61) and a second diffraction grating (64). Here, the first diffraction grating (62) may diffract pulsed laser light (32) corresponding to a first laser light source (LR1). At this time, the pulsed laser light (32) may be provided to the second diffraction grating (64).

[0072] A second diffraction grating (64) may be provided adjacent to the first diffraction grating (62). Here, the second diffraction grating (64) may diffract pulsed laser light (32) and provide it to a crystal (67).

[0073] At this time, the crystal (67) may be placed in the optical path of the second diffraction grating (64) and the mirror (66). Here, the mirror (66) may reflect the diffracted pulsed laser light (32) and transmit most of the line-shaped laser light (LLR) generated from the second laser light source (LR2). At this time, the reflection bandwidth of the mirror (66) may be equal to or greater than the bandwidth of the diffracted pulsed laser light (32).

[0074] For example, the crystal (67) is a gain medium such as Yb:YAG, Nd:YAG, and Nd:YVO4 having a slab shape in the form of a plate, and can be formed into a square shape. As another example, the mirror (66) may be a dichroic mirror that reflects light of a specific wavelength and transmits light of the remaining wavelengths. As yet another example, the second pump laser light source (LR2) may be a fiber-coupled laser diode.

[0075] The crystal (67) can selectively amplify and uniformly a spectrum of the pulsed laser light (32) diffracted through the second diffraction grating (64), and can adjust the gain of the crystal by adjusting the intensity of the line-shaped laser light (LLR) generated from the second pump laser light source (LR2) by position, thereby enabling selective amplification of the spectrum.

[0076] A slab-shaped pulse width compression device (60) according to the present disclosure may further include at least one lens (68) that is provided on the optical path of a mirror (66) and a second laser light source (LR2) and focuses a line-shaped laser light (LLR).

[0077] At least one lens (68) may include a first lens (68a), a second lens (68b), and a third lens (68c). In this case, the first lens (68a) may be positioned on the optical path of the second laser light source (LR2). Additionally, the second lens (68b) may be positioned opposite to the first lens (68a). Additionally, the third lens (68c) may be positioned on the optical path of the mirror (66) and may not be positioned opposite to the second lens (68b).

[0078] These first lens (68a), second lens (68b), and third lens (68c) can focus a line-shaped laser beam (LLR) generated from a second laser light source (LR2) onto a crystal (67). For example, at least one of the first lens (68a), second lens (68b), and third lens (68c) may be a convex lens for efficiently focusing the line-shaped laser beam (LLR) onto the crystal (67). At this time, the focusing intensity at the crystal (67) may be determined according to the focal length of at least one of the first lens (68a), second lens (68b), and third lens (68c).

[0079] That is, the present disclosure describes a diffracted pulsed laser light (32) being focused as a line beam into a gain medium corresponding to any one of Yb:YAG, Nd:YAG, and Nd:YVO4 by a second diffraction grating (64), and the slab-shaped gain medium can selectively amplify the spectrum of the pulsed laser light (32) by a line-shaped pump laser light (LLR) generated from a second laser light source (LR2). Here, the slab-shaped gain medium for amplification may be more diverse.

[0080] The output mirror (61) can reflect the final laser light that has passed through the second diffraction grating (64) and the first diffraction grating (62) to the outside. Here, the output mirror (61) can obtain gain through the crystal (67) gain medium by the line-shaped pump laser light (LLR) of the diffracted pulsed laser light (32), obtain gain again while reflected through the mirror (66), and emit the final laser light with the pulse width compressed after passing through the first diffraction grating (62). At this time, the crystal (67) may be filled with the diffracted pulsed laser light (32) and the line-shaped laser pump light (LLR) without seam. Since the present disclosure can amplify the pulsed laser light (32) branched by wavelength, a higher laser light gain and pulse width compression ratio can be obtained.

[0081] Meanwhile, the reflectance of the mirror (66) according to the present disclosure can be set such that the pulsed laser light (32) is reflected differently depending on the spectral position. At this time, the mirror (66) having reflectance can efficiently adjust the amplification intensity of the pulsed laser light (32) by wavelength. For example, the reflectance of the mirror (66) having reflectance may be adjusted through any one of an external device such as a digital mirror device, a mems mirror device, a deformable mirror device, and an slm. As shown in FIG. 5, the mirror (66) having reflectance can adjust the spectrum of the pulsed laser light (32) to become a uniform state (S1') when the pulsed laser light (32) is in a spectral non-uniform state (S1).

[0082] Referring to FIG. 6, the slab-type pulse width compression device (60) according to the present disclosure may further include an attenuator (69a). Here, the attenuator (69a) is provided in the optical path of the mirror (66) and the third lens (68c) and can attenuate the intensity of the line-type laser light (LLR). At this time, the attenuator (69a) may attenuate the intensity of the line-type laser light (LLR) through an external device. This attenuator (69a) can adjust the positional intensity of the line-type laser light (LLR) so that the gain value is different for each position in the crystal, and as shown in FIG. 5, when the spectrum of the pulse laser light (32) is in a non-uniform state (S1), the spectrum of the pulse laser light (32) can be adjusted to a uniform state (S1').

[0083] Referring to FIG. 7, a slab-shaped pulse width compression device (60) according to the present disclosure may include a third laser light source (LR3), a fourth laser light source (LR4), and fourth to ninth lenses (68d to 68i).

[0084] It can be configured as a slab-shaped pulse width compression device that is pumped in both directions through a line-shaped pump laser light by positioning the third laser light source (LR3) and the fourth laser light source (LR4) opposite each other.

[0085] The fourth to ninth lenses (68d to 68i) are provided in the optical path of the third laser light source (LR3) and the fourth laser light source (LR4) and can further focus the line-shaped laser light (LLR).

[0086] At this time, the fourth lens (68d) may be positioned on the optical path of the third laser light source (LR3). Additionally, the fifth lens (68e) may be positioned opposite the fourth lens (68d). Additionally, the sixth lens (68f) may not be positioned opposite the fifth lens (68e) and may be positioned opposite the crystal (67). Additionally, the seventh lens (68g) may be positioned on the optical path of the fourth laser light source (LR4). Additionally, the eighth lens (68h) may be positioned opposite the seventh lens (68g). Additionally, the ninth lens (68i) may not be positioned opposite the eighth lens (68h) and may be positioned opposite the crystal (67).

[0087] These fourth to ninth lenses (68d to 68i) can focus line-shaped laser light (LLR) generated from the third laser light source (LR3) and the fourth laser light source (LR4) onto the crystal (67). For example, at least one of the fourth to ninth lenses (68d to 68i) may be a convex lens for efficiently focusing line-shaped laser light (LLR) onto the crystal (67). At this time, the focusing intensity at the crystal (67) may be determined according to the focal length of at least one of the fourth to ninth lenses (68d to 68i).

[0088] That is, the present disclosure is a structure in which diffracted pulsed laser light (32) is focused by a second diffraction grating (64) and a mirror (66) into a gain medium corresponding to any one of Yb:YAG, Nd:YAG, and Nd:YVO4, thereby enabling pulse width compression and selective spectral gain simultaneously. Here, the slab-shaped gain medium for amplification may be more diverse.

[0089] The output mirror (61) can reflect the final laser light that has passed through the second diffraction grating (64) and the first diffraction grating (62) to the outside. Here, the output mirror (61) can gain the diffracted pulsed laser light (32) through the gain medium of the crystal (67), gain it again as it is reflected through the mirror (66), and the pulse width of the final laser light that has passed through the first diffraction grating (62) can be compressed and emitted. At this time, the crystal (67) can be filled with the diffracted pulsed laser light (32) and the line-shaped laser light (LLR) without seams. Since the present disclosure can amplify the pulsed laser light (32) branched by wavelength, a higher gain of laser light can be obtained.

[0090] Meanwhile, the reflectance of the mirror (66) according to the present disclosure can be set such that the pulsed laser light (32) is reflected to a predetermined level. At this time, the mirror (66) having the reflectance can efficiently adjust the amplification intensity of the pulsed laser light (32) by wavelength. For example, the reflectance of the mirror (66) having the reflectance may be adjusted through any one of an external device such as a digital mirror device, a mems mirror device, a deformable mirror device, and an slm. As shown in FIG. 5, the mirror (66) having such reflectance can increase the gain of the final laser light by adjusting the spectrum of the pulsed laser light (32) to become uniform (S1') when the pulsed laser light (32) is in a spectral non-uniform state (S1).

[0091] In this way, the present disclosure can efficiently amplify laser light by making the spectrum of the laser light uniform.

[0092] In addition, the present disclosure can amplify laser light branched by wavelength, thereby enabling higher laser light gain.

[0093] In addition, the present disclosure can adjust the spectrum to a uniform state, thereby further compressing the pulse width of the final laser light.

[0094] As described above, the disclosed embodiments have been explained with reference to the attached drawings. Those skilled in the art will understand that the present disclosure may be practiced in forms different from the disclosed embodiments without changing the technical spirit or essential features of the present disclosure. The disclosed embodiments are illustrative and should not be interpreted restrictively.

Claims

1. First laser light source; Second laser light source; A diffraction grating that diffracts laser light generated from the first laser light source; A mirror that reflects the diffracted laser light and transmits the line-shaped laser light generated from the second laser light source; and A slab-shaped pulse width compression device comprising a crystal doped with a slab-shaped gain medium positioned in the optical path between the diffraction grating and the mirror, which amplifies and uniformizes the spectrum of the diffracted laser light and amplifies and uniformizes the spectrum of the line-shaped laser light.

2. In Paragraph 1, A slab-shaped pulse width compression device further comprising at least one lens provided on the optical path of the mirror and the second laser light source and focusing the line-shaped laser light.

3. In Paragraph 1, A slab-shaped pulse width compression device further comprising an attenuator provided on the optical path of the mirror and the third lens and attenuating the intensity of the line-shaped laser light.

4. In Paragraph 1, The reflection band width of the above mirror is, A slab-shaped pulse width compression device having a bandwidth equal to or greater than the bandwidth of the diffracted laser light.

5. In Paragraph 1, It further includes a third laser light source and a fourth laser light source arranged opposite each other to the crystal above, and A slab-shaped pulse width compression device that is pumped bidirectionally through line-shaped laser light generated from the third laser light source and the fourth laser light source.

6. In Paragraph 5, A slab-shaped pulse width compression device further comprising at least one lens provided on the optical path of the third laser light source and the fourth laser light source and focusing the line-shaped laser light.

7. In Paragraph 1, The reflectivity of the above mirror is controlled by an external device, and A slab-shaped pulse width compression device in which the reflectance is set differently according to the wavelength distribution of the diffracted laser light.

8. In Paragraph 1, The above crystal is a slab-type pulse width compression device that amplifies laser light branched by wavelength.

9. In Paragraph 1, A slab-shaped pulse width compression device in which the intensity of the above-mentioned line-shaped laser light is attenuated by an external device.

10. A femtosecond fiber laser system comprising a slab-type pulse width compression device as described in claim 1.

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