Laser system with multi-pass amplifier and methods of using the same

Abstract

A laser system having a multi-pass amplifier system, comprising: at least one seed source configured to output at least one seed signal having a seed signal wavelength; at least one pump source configured to output at least one pump signal; at least one multi-pass amplifier system in communication with the seed source and having at least one gain medium, a first mirror, and at least a second mirror therein, the gain medium device positioned between the first mirror and the second mirror and configured to output at least one amplifier output signal having an output wavelength range, the first mirror and the second mirror can be configured to reflect the amplifier output signal in the output wavelength range; and at least one optical system can be in communication with the amplifier system and configured to receive the amplifier output signal and output an output signal in the output wavelength range.

Description

[0001] This application is a divisional application of application number: 201780075978.6, Invention Name: Laser System Having Multi-Stage Amplifier and Methods of Use Thereof, and its use.

[0002] Cross Reference to Related Applications

[0003] This application claims priority to U.S. Provisional Patent Application Serial No. 62 / 430,862, filed December 6, 2016, entitled "Laser System Having Novel Multi-Stage Amplifier and Methods of Use," the entire contents of which are incorporated herein by reference. BACKGROUND

[0004] Laser systems are currently used in a wide variety of applications. In the past, conventional optically pumped solid state lasers utilized a broadband arc lamp or flash lamp to pump a solid state laser medium laterally or transversely in a resonator cavity. Over time, diode pumped solid state laser systems have become the preferred optically pumped laser system for most applications.

[0005] While currently available diode pumped solid state laser systems have proven useful in the past, a number of shortcomings have been identified. For example, some high power applications require high power pumping of the laser gain medium. Typically, the gain medium receives the pump signal within a confined region of a facet formed on the gain medium. As a result, undesirable effects such as thermal lensing effects within the gain medium have proven problematic. In addition, injecting a seed signal into the gain medium within the confined range of the compact facet has resulted in a reduction in the operational lifetime of certain gain media.

[0006] In view of the foregoing, there exists a continuing need for laser systems having multi-stage amplifiers. SUMMARY

[0007] Various embodiments of laser systems having multi-stage amplifiers are disclosed herein. In some embodiments, laser systems utilizing a single multi-pass amplifier for use in various laser systems will be described in detail in the following paragraphs. In other embodiments, laser systems utilizing a first amplifier and / or pre-amplifier and at least one multi-pass amplifier for use in various laser systems will be described in detail in the following paragraphs. In one particular embodiment, the present application relates to a laser system having a multi-pass amplifier system, and recites at least one seed source configured to output at least one seed signal having a seed signal wavelength. The seed source can be in communication with at least one multi-pass amplifier system. In some embodiments, the amplifier system includes at least one gain medium, a first mirror, and at least a second mirror therein. The gain medium device can be positioned between the first mirror and the second mirror and configured to output at least one amplifier output signal having an output wavelength range. The first mirror and the second mirror can be configured to reflect the amplifier output signal in the output wavelength range. At least one optical system can be in communication with the amplifier system and configured to receive the amplifier output signal and output an output signal in the output wavelength range.

[0008] In another embodiment, the present application relates to a laser system having a multi-pass amplifier system. The laser system includes at least one seed source configured to output at least one seed signal having a seed signal wavelength. At least one first amplifier stage configured to amplify the seed signal and generate at least one amplified seed signal in response thereto is positioned within the laser system. At least one multi-pass second amplifier stage is in communication with the first amplifier stage. The multi-pass second amplifier stage can be configured to receive the amplified seed signal and generate at least one amplifier output signal in an output wavelength range. In one embodiment, the multi-pass second amplifier stage includes at least one gain medium, a first mirror, and at least a second mirror therein. The gain medium device positioned between the first mirror and the second mirror can be configured to output at least one amplifier output signal having an output wavelength range, wherein the first mirror and the second mirror are configured to reflect the amplifier output signal in the output wavelength range. At least one optical system can be in communication with the amplifier system and configured to receive the amplifier output signal and output an output signal in the output wavelength range.

[0009] In yet another embodiment, a laser system having a multi-pass amplifier system is disclosed. The laser system includes at least one seed source configured to output at least one seed signal having a seed signal wavelength. At least one first amplifier stage configured to amplify the at least one seed signal to generate at least one amplified seed signal in response thereto can be in communication with the seed source. At least one multi-pass second amplifier stage configured to receive the at least one amplified seed signal and generate at least one amplifier output signal within an output wavelength range can be in communication with the first amplifier stage. The multi-pass second amplifier stage includes at least one gain medium positioned therein, a first mirror, and at least a second mirror. The gain medium device can be positioned between the first mirror and the at least second mirror and can be configured to output the at least one amplifier output signal having the output wavelength range. The first mirror and the second mirror can include a curved mirror configured to reflect the at least one amplifier output signal within the output wavelength range. At least one optical system can be in communication with the amplifier system and configured to receive the amplifier output signal and output an output signal within the output wavelength range.

[0010] Other features and advantages of laser systems having multi-pass amplifiers as described herein and methods of using the same will become more apparent from consideration of the following detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0011] The novel aspects of laser systems having multi-stage amplifiers as disclosed herein will become more apparent from consideration of the following drawings in which:

[0012] Figure 1 A schematic diagram of an embodiment of a laser system having a multi-stage amplifier architecture is shown;

[0013] Figure 2 A schematic diagram of another embodiment of a laser system having a multi-stage amplifier architecture is shown in which a plurality of first amplifier stages are included therein;

[0014] Figure 3 A schematic diagram of another embodiment of a laser system having a multi-stage amplifier architecture is shown in which a plurality of second amplifier stages are included therein;

[0015] Figure 4 A schematic diagram of another embodiment of a laser system having a multi-stage amplifier architecture is shown in which a plurality of first amplifier stages and a plurality of second amplifier stages are included therein;

[0016] Figure 5 A schematic diagram of another embodiment of a laser system having a multi-stage amplifier architecture is shown in which a plurality of seed a plurality of first amplifier stages and second amplifier stages;

[0017] Figure 6 A schematic diagram of an embodiment of a seed laser system used in an embodiment of a laser system having a multi-stage amplifier architecture is shown;

[0018] Figure 7 A schematic diagram of an embodiment of a first amplifier stage used in an embodiment of a laser system having a multi-stage amplifier architecture is shown;

[0019] Figure 8 A schematic diagram of an embodiment of a second amplifier stage used in an embodiment of a laser system having a multi-stage amplifier architecture is shown;

[0020] Figure 9 A schematic diagram of an embodiment of a second amplifier stage used in an embodiment of a laser system having a multi-stage amplifier architecture is shown, wherein a first reflector and at least a second reflector are used to seed the gain medium device;

[0021] Figure 10 A schematic diagram of an embodiment of a second amplifier stage used in an embodiment of a laser system having a multi-stage amplifier architecture is shown, the gain medium device being pumped by a plurality of pump sources;

[0022] Figure 11 A schematic diagram of an embodiment of a first reflector and at least a second reflector used in an embodiment of a laser system having a multi-stage amplifier is shown, wherein the first reflector and the second reflector are angled with respect to the gain medium device;

[0023] Figure 12 A schematic diagram of an embodiment of a first reflector and at least a second reflector used in an embodiment of a laser system having a multi-stage amplifier is shown, wherein the first reflector and the second reflector are curved;

[0024] Figure 13 A perspective view of an embodiment of a reflector in an embodiment of a laser system having a multi-stage amplifier is shown, wherein the reflector comprises a high-reflectance region and a high-transmission region;

[0025] Figure 14 A schematic diagram of an embodiment of a second amplifier stage used in an embodiment of a laser system having a multi-stage amplifier architecture is shown, the multi-stage amplifier architecture incorporating an embodiment of a reflector device as shown in Figure 13 ;

[0026] Figure 15 Three different values for a thermal lens used in an embodiment of a laser system having a multi-stage amplifier are shown graphically, the effect of the thermal lens on an amplified seed signal as it passes multiple times through a gain medium device;

[0027] Figure 16 The impact of variations in the distance between reflectors used in embodiments of laser systems having multiple amplifier stages is shown graphically;

[0028] Figure 17 The impact of variations in the size of an amplified seed signal used in embodiments of laser systems having multiple amplifier stages using reflectors that are curved in the vertical direction is shown graphically;

[0029] Figure 18 A perspective view of another embodiment of a reflector in an embodiment of a laser system having multiple amplifier stages is shown, in which the reflector includes a high-reflectance region and a high-transmission region; and

[0030] Figure 19 A schematic diagram of an embodiment of a second amplifier stage used in an embodiment of a laser system having a multiple amplifier stage architecture that incorporates an embodiment of a reflector apparatus as shown in Figure 18 is shown. DETAILED DESCRIPTION

[0031] Various embodiments of multiple-stage laser amplifiers for use in various laser systems will be described in detail in the following paragraphs. Figures 1-5 Various embodiments of laser systems incorporating multiple amplifier configurations are shown. As Figure 1 shown in FIG. 1, in one embodiment, a laser system 10 includes at least one seed source 20 configured to output at least one seed signal 56 to at least one first amplifier stage 60. Figure 1 A seed source 20 outputting a single seed signal 56 to a single first amplifier stage 60 is shown. In contrast, Figure 2 and 3 A single seed source 20 outputting multiple seed signals 56 to multiple first amplifier stages 60a, 60b is shown. Additionally, Figure 3 A single seed source 20 outputting a single seed signal to a single first amplifier stage 60 is shown, which outputs multiple amplified signals 86 to multiple second amplifier stages 100a and 100b. Additionally, Figure 4 A single seed source 20 outputting multiple seed signals to multiple first amplifier stages 60a and 60b and multiple second stages 100a and 100b is shown. Additionally, as Figure 5 shown in FIG. 1, multiple seed sources 20a, 20b can be used to deliver multiple seed signals 56 to one or more first amplifier stages 60a, 60b. Those skilled in the art will appreciate that any number of seed sources can be configured to output any number of seed signals to any number of first amplifier stages 60.

[0032] As Figure 1 indicated in Figures 1-5 , various embodiments of the laser system 10, the one or more optical systems, devices, or components 58 (hereinafter "optical devices") can be positioned anywhere within. More specifically, Figure 1 and Figure 4 various embodiments of the laser system are shown having one or more optical systems 58 positioned therein, it is understood that any number of optical systems and / or devices 58 can be used throughout the various embodiments of the laser system shown in Figures 1-5 In one embodiment, the optical devices 58 include one or more wavelength filters. Exemplary wavelength filters include, but are not limited to, one or more dichroic mirrors, wavelength selective devices, filters, and the like. In another embodiment, the optical devices 58 include one or more lenses. In another embodiment, the optical devices 58 include one or more sensors. Those skilled in the art will appreciate that any kind of optical device can be used in the present laser system, including but not limited to lenses, filters, mirrors, sensors, modulators, polarizers, waveplates, masks, attenuators, wavelength filters, spatial filters, and the like.

[0033] Referring again to Figure 1 , the first amplifier stage 60 can be configured to receive the seed signal 56 from the seed source 20 and amplify the seed signal 56 to produce at least one amplified seed signal 86. In one embodiment, the first amplifier stage 60 is configured to output a single amplified seed signal 86 to a single second amplifier stage 100 (see Figure 1 and 5 ). In contrast, Figure 2 multiple first amplifier stages 60a, 60b, each of which outputs a single amplified seed signal 86 to a single second amplifier stage 100. In an alternative, Figure 3 embodiments of the laser system 10 having a single first amplifier stage 60 that outputs multiple amplified seed signals 86 to multiple second amplifier stages 100a, 100b. Any number of first amplifier stages 60 can be used within the laser system 10. Furthermore, in Figure 2In the embodiments shown in FIGS. 1-5, the first amplifier stages 60a, 60b are shown in a parallel configuration. However, those skilled in the art will appreciate that the first amplifier stages 60a, 60b can be positioned sequentially (in series). Similarly, the various components of the laser system 10, including the seed sources 20a, 20b, the first amplifier stages 60a, 60b, and / or the second amplifier stages 100a, 100b (if present) can be configured with a parallel architecture, or sequentially with a serial configuration, or any combination thereof.

[0034] As shown in FIGS. 1-5, the laser system 10 can include at least one second amplifier stage 100 therein. In the illustrated embodiments, the second amplifier stage 100 can be in communication with one or more first amplifier stages 60 positioned within the laser system 10. Figure 1 Figure 1 As shown in FIGS. 1-5, the laser system 10 can include at least one second amplifier stage 100 therein. In the illustrated embodiments, the second amplifier stage 100 can be in communication with one or more first amplifier stages 60 positioned within the laser system 10. 2 Figures 3-5 Embodiments of a laser system having a single second amplifier stage 100 positioned therein are shown. Alternatively, as shown in FIGS. 1-5, various embodiments of a laser system have multiple second amplifier stages 100a, 100b positioned therein. In one embodiment, the second amplifier stages 100a, 100b are in communication with a single first amplifier stage 60. Alternatively, the multiple second amplifier stages 100a, 100b are in communication with one or more first amplifier stages 60a, 60b (see FIGS. 1-5). Figure 2 4 Any number of second amplifier stages 100 can be used in the laser system 10. Furthermore, any number of additional amplifier stages can be used with the laser system 10.

[0035] As shown in FIGS. 1-5, at least one amplified output signal 110 can be emitted from one or more second amplifier stages 100 positioned within the laser system 10. As shown in FIGS. 1-5, a single amplified output signal 110 is emitted from the second amplifier stage 100. In the alternative, Figures 1-5 Figure 1 2 As shown in FIGS. 1-5, at least one amplified output signal 110 can be emitted from one or more second amplifier stages 100 positioned within the laser system 10. As shown in FIGS. 1-5, a single amplified output signal 110 is emitted from the second amplifier stage 100. In the alternative, Figures 3-5 ​​​​​Various embodiments of a laser system 10 are illustrated, wherein a plurality of amplified output signals 110 are emitted from a plurality of second amplifier stages 100 located within the laser system 10. In the illustrated embodiment, the amplified output signals 110 are directed to one or more optical systems or devices 200 configured to output at least one output signal 250. In one embodiment, the optical system 200 includes one or more isolators. In another embodiment, the optical system 200 includes one or more modulators. Optionally, the optical system 200 may include at least one telescope. Furthermore, the optical system 200 may include one or more laser systems, amplifiers, etc. For example, the optical system 200 may include one or more additional multistage amplifiers. The additional multistage amplifiers 200 may include one or more single-pass amplifiers. Optionally, the additional multistage amplifiers 200 may include one or more multi-pass amplifiers. In another embodiment, the optical system 200 may include at least one single-stage amplifier. Optionally, the optical system 200 may include one or more nonlinear optical crystals. Optionally, the laser system 10 may not need to include the optical system 200.

[0036] Figure 6 It shows the use of with Figure 1 This is a schematic diagram of an embodiment of a seed source 20 used in conjunction with the laser system 10 shown. As illustrated, the seed source 20 includes at least one seed laser 22. In one embodiment, the seed laser 22 includes a diode laser system. For example, the seed laser 22 may include one or more gain-switching diode laser systems. In another embodiment, the seed laser includes one or more fiber-amplified diode laser sources. Furthermore, the seed source 20 may include an injected seed diode laser system. Optionally, the seed source 22 may include one or more fiber laser devices. In short, any type of laser system can be used as the seed laser 22 in the seed source 20.

[0037] The seed laser 22 can be configured to output at least one seed signal 24 having a wavelength from about 400 nm to about 1400 nm. For example, in one embodiment, the seed laser 22 outputs a seed signal 24 having a wavelength from about 600 nm to about 1200 nm. For example, the seed signal 24 can have a wavelength of about 1064 nm. In yet another embodiment, the seed signal 24 has a wavelength of about 1030 nm. Further, the seed laser 22 can be configured to output a pulsed output. For example, the seed laser 22 can be configured to output a seed signal 24 having a repetition rate of 100 kHz or more. In another embodiment, the seed laser 22 can be configured to output a seed signal 24 having a repetition rate of 1 MHz or more. Optionally, the seed laser 22 can be configured to output a seed signal 24 having a repetition rate of 15 MHz or more. For example, the seed laser 22 can be configured to output a seed signal 24 having a repetition rate of about 20 MHz. Optionally, the seed laser 22 can be configured to output a seed signal 24 having a repetition rate of 10 kHz.

[0038] Referring again to Figure 6 , the seed laser 22 can be configured to output a seed signal 24 having any desired pulse width. In one embodiment, the seed laser 22 can be configured to output a seed signal 24 having a pulse width of less than about 100 ps. In another embodiment, the seed laser 22 can be configured to output a seed signal 24 having a pulse width of less than about 50 ps. Optionally, the seed laser 22 can be configured to output a seed signal 24 having a pulse width of less than about 25 ps. In another embodiment, the seed laser 22 can be configured to output a seed signal 24 having a pulse width of less than about 1 ps. Further, the seed laser 22 can be configured to output a seed signal 24 having a power of about 1 μW to about 200 μW. For example, the seed laser 22 can be configured to output a seed signal 24 having a power of about 40 μW to about 80 μW. In another embodiment, the seed laser 22 can be configured to output a seed signal 24 having a power of about 65 μW to about 85 μW.

[0039] Referring again to Figure 6Seed source 20 can include one or more optical filters 26 configured to filter seed signal 24 to produce at least one filtered or chirped signal 32 (hereinafter referred to as "filtered signal"). In one embodiment, optical filters 26 include at least one Bragg reflector. For example, optical filters 26 can include at least one chirped fiber Bragg grating. In the illustrated embodiment, optical filters 26 are in communication with at least one sensor or control device 28 via at least one conduit 30. For example, during use, control device 28 can be configured to allow a user to selectively vary the range of wavelength transmission through optical filters 26. Thereby, the wavelength characteristics of chirped signal 32 can be readily varied. Optionally, optical filters 26 can be configured to allow a user to selectively adjust any kind of characteristic of chirped signal 32.

[0040] As shown in Figure 6 First amplifier 34 can be included within seed source 20 to amplify chirped signal 32. In one embodiment, first amplifier 34 includes at least one fiber amplifier. In one embodiment, the type of first amplifier 34 and second amplifier 42 (if present) used in seed source 20 can depend on the type of amplifier stage 60 and second amplifier stage 100 used in laser system 10. For example, if first and second amplifier stages 60, 100 include Yb:YAG, a Yb:fiber amplifier operating at about 1030 nm wavelength can be used as first amplifier 34 in seed source 20. In contrast, if first and second amplifier stages 60, 100 include Nd:YVO4, a Yb:fiber amplifier operating at about 1064 nm wavelength can be used as first amplifier 34 in seed source 20. Optionally, any kind of device can be used in seed source 20. First amplifier 34 is configured to amplify signal 32 to produce at least one amplified seed signal 36, which can be directed into at least one modulator system or device 38.

[0041] Referring again to Figure 6The modulator device 38 is configured to alter the repetition rate of the pulse-amplified seed signal 36 to produce at least one modulated amplified seed signal 40. In one embodiment, the modulator device 38 is configured to output a modulated seed signal 40 having a repetition rate of about 5 kHz to about 1000 kHz. In another embodiment, the modulator device 38 is configured to output a modulated amplified seed signal 40 having a repetition rate of about 100 kHz to about 500 kHz. Optionally, the modulator device 38 is configured to output a modulated amplified seed signal 40 having a repetition rate of about 250 kHz to about 350 kHz. For example, the modulator device 38 is configured to output a modulated amplified seed signal 40 having a repetition rate of about 333 kHz. In one embodiment, the modulator device 38 is configured to output a modulated seed signal 40 having a repetition rate greater than 1000 kHz. In one embodiment, the modulator device 48 comprises an acousto-optic modulator. Optionally, any kind of alternative device can be used, including but not limited to electro-optic modulators, amplitude modulators, phase modulators, liquid crystal modulators, and the like. In an alternative embodiment, the seed source 20 does not include a modulator device 38.

[0042] As Figure 6As shown in FIG. 1, the seed source 20 can include at least one first amplifier 22 configured to amplify the seed signal 24 to produce at least one amplified seed signal 26. In one embodiment, the first amplifier 22 includes at least one Yb:fiber amplifier. Alternatively, any type of device can be used in the seed source 20. For example, a solid state amplifier can be optionally used in place of or in addition to the fiber amplifier. Further, any number of additional amplifiers can be used in the seed source 20. The amplified seed signal 26 can be directed into at least one isolator 28 positioned within or in communication with the seed source 20. In one embodiment, the isolator 28 is configured to reduce or eliminate back-reflection of an amplified seed signal output 30 from the seed source 20. Those skilled in the art will appreciate that any number of isolators 28 can be used anywhere within the seed source 20. The isolator 28 can be configured to output at least one modulated seed signal 32 to at least one second amplifier 34 of the laser system 10. In one embodiment, the modulated seed signal 32 has a pulse width of about 1 ps to about 100 ps and a pulse energy of about 10 μJ to about 70 μJ. For example, the modulated seed signal 32 can have a pulse width of about 20 ps and a pulse energy of about 40 μJ. Further, the modulated seed signal 32 can have a repetition rate of about 300 kHz to about 450 kHz and a power of about 5 mW to about 100 mW. Alternatively, any type of additional optical element or device can be used in the seed source 20, including but not limited to lenses, mirrors, folding mirrors, flat mirrors, curved mirrors, dichroic filters, notch filters, gratings, sensors, filters, attenuators, modulators, circulators, fiber Bragg gratings, laser diodes, volume Bragg gratings, and the like. In the illustrated embodiment, the various components of the seed source 20 are positioned within at least one housing 36. Those skilled in the art will appreciate that the various components of the seed source 20 can be positioned within multiple housings, or can alternatively be located within another subsystem of the laser system 10.

[0043] Figure 7 The above-described embodiments of the application are presented for purposes of illustration and description. They are not intended to be exhaustive of or to limit the application to the precise forms described. Many modifications and variations are possible in light of the above teachings. For example, the described embodiments can be applied to other types of laser systems. Further, the described embodiments can be applied to other types of optical systems. Other embodiments can be apparent to those skilled in the art from consideration of the specification and can be practiced without departing from the spirit or scope of the application. For example, the described embodiments can be applied to other types of laser systems. Further, the described embodiments can be applied to other types of optical systems. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims. Figures 1-5The first amplifier stage 60 can include at least one housing 62 configured to contain the various components of the first amplifier stage 60 therein. Optionally, the first amplifier stage 60 need not include a housing 62. At least one first amplifier pump source 64 can be used to generate at least one pump signal 76. In the illustrated embodiment, the first amplifier pump source 64 includes a fiber-coupled diode pump source configured to output at least one pump signal 76 having a wavelength from about 600 nm to about 1000 nm; although one skilled in the art will appreciate that any sort of pump source can be used within the first amplifier pump source 64. In one embodiment, the pump signal 76 has a wavelength of about 900 nm to about 1000 nm. For example, the pump signal 76 can have a wavelength of about 940 nm. In another embodiment, the pump signal 76 can have a wavelength of about 969 nm. Optionally, the pump signal 76 can have a wavelength of about 808 nm. In another embodiment, the pump signal 76 can have a wavelength of about 880 nm. Further, the pump source 62 can be configured to output a continuous wave pump signal, or alternatively, to output a pulsed pump signal. For example, the pump signal 76 can have a repetition rate of about 1 kHz to 100 MHz or more. For example, in one embodiment, the pump signal 76 has a repetition rate of about 10 kHz. In another embodiment, the pulsed signal 76 has a repetition rate of about 50 MHz to about 125 MHz.

[0044] Referring again to Figure 7 , at least one fiber conduit 66 can be used to deliver the pump signal 76 to a desired location. Optionally, the pump source 64 need not include a fiber conduit 66. The fiber conduit 66 terminates at at least one pump signal delivery system 70. In one embodiment, the pump signal delivery system 70 includes a cleaved fiber facet. In another embodiment, the pump signal delivery system 70 can include one or more lenses, mirrors, filters, sensors, positioning devices such as V-grooves, chucks, and the like, and similar devices. In the illustrated embodiment, at least one optical component 72 is coupled to the pump signal delivery system 70, although the pump signal delivery system 70 can include such elements therein, or can operate without including such devices.

[0045] As shown, a pump signal 76 is directed from the pump signal delivery system 70, passes through at least one reflector 74, and is incident on at least one gain medium 82 positioned within a first amplifier stage 60. In one embodiment, the reflector 74 includes at least one dichroic mirror configured to transmit at least one optical signal with a wavelength less than about 1000 nm while reflecting substantially all light with wavelengths greater than about 1000 nm. Those skilled in the art will appreciate that any type of optical reflector configured to transmit at least one optical signal with a wavelength less than about 1000 nm while reflecting substantially all light with wavelengths greater than about 1000 nm can be used in this system. Furthermore, the reflector 74 can be configured to transmit at least one optical signal with a wavelength less than about 1000 nm while reflecting substantially all light with wavelengths greater than about 1020 nm. In another embodiment, the reflector 74 can be configured to transmit at least one optical signal with a wavelength less than about 1000 nm while reflecting substantially all light with wavelengths greater than about 1020 nm. In yet another embodiment, the reflector 74 can be configured to transmit multiple optical signals. For example, reflector 74 can be configured to transmit at least one optical signal with a wavelength less than about 1000 nm and at least one optical signal with a wavelength greater than about 1100 nm, while reflecting substantially all light with a wavelength of about 1064 nm. In another embodiment, reflector 74 can be configured to transmit at least one optical signal with a wavelength less than about 1000 nm and at least one optical signal with a wavelength greater than about 1100 nm, while reflecting substantially all light with a wavelength of about 1030 nm.

[0046] Refer again Figure 7 Optionally, at least the optical element 80 may be positioned anywhere within the first amplifier stage 60. Exemplary optical elements 80 include, but are not limited to, folding mirrors, plane mirrors, curved mirrors, lenses, thermal management devices, fans, coolers, filters, and the like. As shown, the pump signal 76 passes through the optical element 80 and is incident on the gain medium 82. In one embodiment, the gain medium 82 comprises at least one plate, rod, disk, or similar body made of a desired gain material. Exemplary gain materials include, but are not limited to, Nd:YVO4, Nd:GdVO4, Nd:YAG, Nd:YLF, Nd:glass, Yb:YAG, Yb:KGW, Yb:CaF2, Yb:CALGO, Yb:Lu2O3, Yb:S-FAP, Yb:glass, semiconductor gain media, ceramic laser materials, and the like.

[0047] like Figure 7 As shown, at least one seed signal 56 from at least one seed source (see Figures 1-5) on the gain medium 82, which amplifies the seed signal 56 to output at least one amplified seed signal 86. For example, in one embodiment, the seed signal 56 has a pulse width of approximately 20 ps, a pulse energy of approximately 40 μJ, a repetition rate of approximately 333 kHz, and a power of approximately 5 mW to approximately 15 mW prior to amplification. Thereafter, the first amplifier stage 60 can be configured to output at least one amplified seed signal 86 to the second amplifier stage 100, which can have a pulse width of approximately 20 ps, a pulse energy of approximately 18 μJ, a repetition rate of approximately 333 kHz, and a power of approximately 5 W to approximately 15 W. Those skilled in the art will appreciate that any number of first amplifier stages 60 can be used in the laser system 10.

[0048] Figures 8-14 Various embodiments of a second amplifier stage 100 for use in a multi-stage amplifier of a laser system are shown. As shown, the second amplifier stage 100 can be positioned within a housing 112, or alternatively, can be positioned within a housing of a larger optical system or laser. As shown, the second amplifier stage 100 includes at least one gain medium device 120 therein. In one embodiment, the gain medium device 120 is Yb:YAG. In another embodiment, the gain medium device 120 is Nd:YVO4. Exemplary gain materials include, but are not limited to, Nd:YVO4, Nd:GdVO4, Nd:YAG, Nd:YLF, Nd:glass, Yb:YAG, Yb:KGW, Yb:CaF2, Yb:CALGO, Yb:Lu2O3, Yb:S-FAP, Yb:glass, semiconductor gain media, ceramic laser materials, and the like. In one embodiment, the gain medium device 120 includes at least one plate, rod, disk, or similar body composed of a desired gain material. For example, in the illustrated embodiment, the gain medium device 120 includes an elongated facet F Lon and a compact facet F Com . As such, the length of the elongated facet F Lon may be greater than the length of the compact facet F Com . In the illustrated embodiment, the energy and / or fluence of the seed signal 86 incident on the gain medium device 120 is distributed more on the at least one elongated facet F Lon (i.e., lateral pumping), thereby reducing the effects of thermal lensing while simultaneously reducing the likelihood of damaging the gain medium device 120. In the alternative, those skilled in the art will appreciate that the gain medium device 120 can be seeded via the compact facet F Com . In another embodiment, the gain medium device 120 can be seeded via the elongated facet F Lon and the compact facet F Comto seed the gain medium apparatus 120. As a result, those skilled in the art will appreciate that the gain medium apparatus 120 can be fabricated in any variety of shapes, sizes, and configurations.

[0049] Referring again to Figures 8-14 The gain medium apparatus 120 can be proximate to at least one reflector. In the illustrated embodiment, the gain medium apparatus 120 is positioned between two reflectors 132 that are configured to reflect at least a portion of the at least one amplified signal 86 from the at least one first amplifier stage 60 into the gain medium apparatus 120. The gain medium apparatus 120 is configured to be pumped by at least one pump source 122. Optionally, any variety of alternative laser systems can be used to pump the gain medium apparatus 120. Further, the at least one pump source 122 can be configured to output at least one pump signal 130 having a wavelength from about 600 nm to about 1000 nm. In one embodiment, the pump signal 130 has a wavelength of about 900 nm to about 1000 nm. For example, the pump signal 130 can have a wavelength of about 940 nm. In another embodiment, the pump signal 130 can have a wavelength of about 969 nm. Optionally, the pump signal 130 can have a wavelength of about 808 nm. In another embodiment, the pump signal 130 can have a wavelength of about 880 nm. Further, the pump source 122 can be configured to output a continuous wave pump signal, or alternatively, to output a pulsed pump signal. For example, the pump signal 130 can have a repetition rate of about 1 kHz to 100 MHz or more. For example, in one embodiment, the pump signal 130 has a repetition rate of about 10 kHz. In another embodiment, the pulsed signal 130 has a repetition rate of about 50 MHz to about 125 MHz.

[0050] In the illustrated embodiment, a plurality of fiber-coupled diode pump sources 122 are configured to provide one or more pump signals 130 to the gain medium apparatus 120. In the illustrated embodiment, the diode pump sources 122 are coupled to at least one fiber conduit 126. The fiber conduit 126 can, but need not be, coupled to one or more pump signal delivery systems 124 (see Figure 10). In one embodiment, the pump signal delivery system 124 can include one or more V-grooves or similar positioning features configured to tightly align or otherwise position the one or more fiber conduits 126. In one embodiment, the fiber conduits 126 are separated by a distance of less than about 500 um. In another embodiment, the fiber conduits 126 are separated by a distance of greater than about 500 um. In yet another embodiment, the fiber conduits 126 are separated by a distance of about 100 um. As such, the fiber conduits 126 can be positioned so as to produce an output having an elongated profile, such as the output of an elongated pump source, such as a diode bar, light pipe, waveguide, or similar structure. As Figure 10 shown in FIG. 1, the pump signal delivery system 124 can include one or more filters, sensors, lenses, or the like configured to direct the pump signal 130 to the gain medium device 120. For example, in the illustrated example, one or more lenses or similar optical components 128, 134 can be used to form a telescope, collimator, homogenizer, diffractive beam shaper, refractive beam shaper, lens array, or the like to condition the pump signal 130 for the pump gain medium device 120. In one embodiment, multiple optical components 128, 134 can be positioned proximate to the multiple fiber conduits 126 (see FIG. 1). In an alternative embodiment, a single optical component 128, 134 can be used instead of multiple separate optical components. Figure 10

[0051] As Figure 8 and 10 ​As shown, a pump signal 130 is directed from the pump signal delivery system 126, through at least one reflector 132, and incident on at least one gain medium device 120 positioned within a second amplifier stage 100. In the illustrated embodiment, the gain medium device 120 is laterally pumped by the pump signal 130. In another embodiment, the gain medium device 120 is pumped by the pump signal 130 along an elongated facet of the gain medium device 120. Optionally, the gain medium device 120 may be end-pumped by the pump signal 130. In one embodiment, the reflector 132 includes at least one dichroic mirror (planar or curved) configured to transmit at least one optical signal with a wavelength less than about 1000 nm while reflecting substantially all light with wavelengths greater than about 1000 nm. Those skilled in the art will appreciate that any type of optical reflector configured to transmit at least one optical signal with a wavelength less than about 1000 nm while reflecting substantially all light with wavelengths greater than about 1000 nm can be used in this system. Furthermore, reflector 132 can be configured to transmit at least one optical signal with a wavelength less than about 1000 nm, while reflecting substantially all light with wavelengths greater than about 1020 nm. In another embodiment, reflector 132 can be configured to transmit at least one optical signal with a wavelength less than about 1000 nm, while reflecting substantially all light with wavelengths greater than about 1030 nm. In another embodiment, reflector 132 can be configured to transmit multiple optical signals. For example, reflector 132 can be configured to transmit at least one optical signal with a wavelength less than about 1000 nm and at least one optical signal with a wavelength greater than about 1100 nm, while reflecting substantially all light with a wavelength of about 1064 nm. In another embodiment, reflector 132 can be configured to transmit at least one optical signal with a wavelength less than about 1000 nm and at least one optical signal with a wavelength greater than about 1100 nm, while reflecting substantially all light with a wavelength of about 1030 nm.

[0052] like Figures 8-10 As shown, reflector 132 receives the amplified seed signal 86 and repeatedly directs the seed signal 86 into gain medium device 120 for multi-pass amplification, thereby outputting an amplified output signal 110. For example, in one embodiment, the amplified seed signal has a pulse width of approximately 20 ps, ​​a pulse energy of approximately 18 μJ, a repetition rate of approximately 333 kHz, and a power of approximately 5 W to approximately 15 W, while the output of the second amplifier stage 120 has a pulse width of approximately 20 ps, ​​a pulse energy of approximately 175 μJ, a repetition rate of approximately 333 kHz, and a power of approximately 58 W or higher.

[0053] Figure 11An alternative embodiment of the reflector used in the second amplifier stage 100 is shown. As shown, the reflector 132 includes a substantially planar body, wherein at least one reflector is positioned at a slight wedge angle with respect to the gain medium device 120. In the alternative, Figure 12 The reflector 132 is shown to include a substantially curved body. Those skilled in the art will appreciate that the reflector 132 can be fabricated with any desired shape, size, and configuration. Optionally, at least one reflector can include high-reflectivity regions or zones and high-transmission regions or zones formed thereon at the desired wavelengths. For example, Figure 13 and 14 An embodiment of a novel "streaked" reflector 140 having a reflector body 142 is shown. As shown, the reflector body 142 includes a high-reflectivity region or zone 144 at the desired wavelengths, and a high-transmission region or zone 146 at the desired wavelengths. During use, the amplified seed signal 86 is incident on the reflector body 142. In one embodiment, the at least one reflector body 142 is aligned such that the amplified seed signal 86 is incident on the high-reflectivity region or zone 144 formed on the reflector body 142. As Figure 14 shown in FIG. 1C, the parasitic signals 148 (including Raman-generated signals) formed within the gain medium device 120 can be incident on the high-transmission region or zone, thereby allowing the parasitic signals 148 to be extracted, suppressed, and / or not reflected by the reflector 140. The high-reflectivity region is configured to reflect substantially all of the amplified output signal 110 through the gain medium device 120, while the high-transmission region is configured to transmit substantially all of the parasitic signals generated within the gain medium device 120 during use, as well as the unabsorbed amplified seed signal 86 and unused pump signal 130 (see Figure 10 ). As shown, the parasitic signals or unused signals 148 can be transmitted through the reflector 132. In another embodiment, the reflector 140 includes at least one high-transmission region 146 formed by applying at least one anti-reflective coating on the reflector body 142. Thereafter, one or more high-reflectivity regions 144 at the desired wavelengths can be formed by selectively applying wavelength-dependent reflector material on the coated reflector body 142.

[0054] Referring now to Figure 8 , the gain medium device 120 receives one or more pump signals 130 from a diode pump source 122. In one embodiment, the diode pump source 122 causes a thermal lens to form in the gain medium device 120, which is substantially in the vertical direction. As the amplified seed signal 86 passes through the gain medium device 120 multiple times, as Figure 8 and 9As shown in FIG. 6, the amplified seed signal 86 can be affected by thermal lensing. Figure 15 The effect of thermal lensing on the amplified seed signal 86 as it passes through the gain medium device 120 multiple times is shown for three different values of the thermal lens. As is apparent, there is substantially one value of the thermal lens (f TL = 600 mm) that results in the size of the amplified seed signal 86 remaining substantially constant as it passes through the gain medium device 120 and exits as the amplified output 110. For any other value of the thermal lens, the amplified seed signal 86 will change in size as it is affected by the thermal lens in the gain medium device 120. This change in size can result in deleterious effects such as, but not limited to, loss of efficiency due to poor overlap with one or more pump beams, degradation of beam quality, or the beam beginning to interfere with other components or becoming small enough (such as Figure 15 the case shown in FIG. 6, where the thermal lens is f TL = 400 mm), even damage can occur.

[0055] Figure 16 The change in size of the amplified seed signal 86 is shown for different distances of the reflector 132 from the gain medium device 120 for a substantially fixed value of the thermal lens f TL = 400 mm. If, in an alternative embodiment, the distance between the reflector 132 and the gain medium device 120 is increased from approximately 15 mm to approximately 23 mm, as shown in FIG. 7, the size of the amplified seed signal 86 will again be substantially constant as it passes through the gain medium device 120 multiple times. Figure 16

[0056] Figure 17 The change in size of the amplified seed signal 86 is shown for still another embodiment, in which the reflector 132 is curved in the vertical direction. For a thermal lens value of f TL = 400 mm and a separation of approximately 15 mm, if the reflector 132 has a curvature with a radius of curvature of approximately -2400 mm, the size of the amplified seed signal 86 can again be substantially constant as it passes through the gain medium device 120 multiple times.

[0057] Figure 18 and 19 Alternative embodiments of novel reflectors that can be used in the laser systems disclosed herein are shown. As shown in FIG. 8, a reflector 132 can be curved in the horizontal direction. The change in size of the amplified seed signal 86 is shown for a thermal lens value of f Figure 18 ​As shown, the reflector 240 includes a reflector body 242. As illustrated, the reflector body 242 includes a large single high reflectivity region or area 244 at the desired wavelength and a single high transmittance region or area 246 at the desired wavelength. For example, the high transmittance region or area 246 may be configured to transmit substantially all of the optical signal incident thereon. Furthermore, the high reflectivity region or area 244 may be configured to selectively reflect substantially all light with wavelengths greater than about 1000 nm, while selectively transmitting light with wavelengths less than about 1000 nm via it. In another embodiment, the high reflectivity region or area 244 may be configured to selectively reflect substantially all light with wavelengths greater than about 1020 nm, while transmitting light with wavelengths greater than about 1000 nm via it. Optionally, the high reflectivity region or area 244 may be configured to selectively reflect substantially all light with wavelengths greater than about 1030 nm, while transmitting light with wavelengths less than about 1000 nm via it. In another embodiment, the reflector 132 may be configured to transmit multiple optical signals. For example, reflector 132 may be configured to transmit at least one optical signal with a wavelength less than about 1000 nm and at least one optical signal with a wavelength greater than about 1100 nm, while substantially reflecting all light with a wavelength of about 1064 nm. In another embodiment, reflector 132 may be configured to transmit at least one optical signal with a wavelength less than about 1000 nm and at least one optical signal with a wavelength greater than about 1100 nm, while substantially reflecting all light with a wavelength of about 1030 nm. In another embodiment, the high reflectivity region 244 and the high transmittance region 246 on the novel reflector body 242 may be substantially the same region. More specifically, reflector 240 may include a dichroic mirror configured to reflect light within a desired wavelength range (i.e., about 1020 nm to about 1100 nm) while transmitting light outside its transmission wavelength range. In another embodiment, reflector 240 may include a concave mirror.

[0058] During use, such as Figure 19 As shown, the amplified seed signal 86 is incident on the reflector body 242. As illustrated, the amplified seed signal 86 can travel along the elongated facet F of the gain medium device 120. Lon Incident. Similarly, the gain medium device 120 can be powered by at least one pump signal 230 along an elongated plane F. Lon Pumps, such as Figure 10The angle at which the amplified seed signal 86 is incident on the gain medium device 120 can also be selected to optimize the number of passes of the amplified seed signal 86 through the gain medium device 120. The alignment of the at least one reflector body 142 can also be configured to optimize the number of passes of the amplified seed signal 86 through the gain medium device 120. As a result, the gain medium device 120 can be infiltrated by the amplified seed signal 86, thereby suppressing the generation of parasitic signals (including Raman generated signals) within the gain medium device 120. The high reflectivity region 244 is configured to reflect substantially all of the amplified output signal 110 generated by the multiple passes through the gain medium device 120. In addition, the high reflectivity region 244 is configured to transmit unabsorbed seed signal, unused pump signal 230, and / or parasitic signals generated during the amplification process therethrough. In the illustrated embodiment, the amplified output signal 110 can be extracted from the multi-pass amplifier 100 via at least one high transmission region or zone 246 formed on the at least one reflector 240.

[0059] The embodiments disclosed herein are illustrative of the principles of the present application. Other modifications can be employed within the scope of the application. Accordingly, the devices disclosed in the specification are not intended to be limited to the exact devices as shown and described herein.

Claims

1. A laser system with a multi-pass amplifier system, comprising: At least one seed source is configured to output at least one seed signal having a seed signal wavelength; At least one pump source is configured to provide at least one pump signal having at least one pump signal wavelength; At least one first amplifier stage is configured to amplify at least one seed signal in response to generate at least one amplified seed signal; At least one multi-pass second amplifier stage is configured to receive at least one amplified seed signal; At least one gain medium device is located within at least one multi-pass second amplifier, the gain medium device having at least one elongated facet and at least one compact facet, the at least one gain medium device being pumped by at least one pump signal and configured to receive at least one amplified seed signal and output at least one amplifier output signal having an output wavelength range; A first reflector and at least a second reflector are positioned within at least one multi-pass second amplifier stage, wherein at least one gain dielectric device is positioned between and separate from the first reflector and the at least second reflector, and at least one of the first reflector and at least the at least second reflector has a high reflectivity region in the output wavelength range and a high transmission region at wavelengths outside the output wavelength range. The first and second reflectors are configured to receive the amplified seed signal and repeatedly guide the seed signal into the gain medium device for multi-pass amplification, thereby outputting an amplified output signal and transmitting a pump signal for pumping the gain medium. The at least one high-transmission region formed on at least one of the first reflector and at least one of the second reflectors is configured to transmit at least one of the following: at least one pump signal, at least one unabsorbed seed signal, and at least one parasitic signal generated during the amplification process. At least one optical system, which communicates with at least one multi-pass amplifier system, and is configured to receive at least one amplifier output signal and output at least one output signal in an output wavelength range. The at least one gain medium device is pumped by at least one pump signal on at least one elongated facet, and the at least one gain medium device is configured to receive at least one amplified seed signal on at least one elongated facet; and wherein a first reflector and at least a second reflector are aligned to reflect at least one amplifier output signal and suppress reflection of at least one of at least one pump signal and at least one parasitic signal within at least one multi-pass second amplifier stage.

2. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one seed source comprises at least one gain-switching diode laser system.

3. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one seed source comprises at least one fiber amplifier diode laser system.

4. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one seed source is configured to output at least one seed signal with a wavelength of 1000 nm to 1100 nm.

5. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one seed source is configured to output at least one seed signal with a wavelength of 1064 nm.

6. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one seed source is configured to output at least one seed signal with a wavelength of 1030 nm.

7. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one pump source comprises a plurality of fiber-coupled diodes.

8. The laser system with a multi-pass amplifier system as claimed in claim 7, wherein at least one pump source comprises: At least one positioning feature is configured to position one or more fiber optic conduits of at least one pump source to generate at least one pump signal output having an elongated profile.

9. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one pump signal wavelength is less than 1000 nm.

10. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one seed source comprises a pulse seed source with a repetition rate of 100 kHz or higher.

11. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one seed source comprises a pulse seed source with a repetition rate of 10 kHz or higher.

12. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one amplified seed signal is incident on at least one elongated facet of at least one gain medium device.

13. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one pump signal is incident on at least one elongated small plane of at least one gain dielectric device.

14. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one pump signal and at least one amplified seed signal are incident on at least one elongated facet of at least one gain dielectric device.

15. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one parasitic signal comprises a Raman-generated signal.

16. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one of the first mirror and at least one second mirror comprises a curved mirror.

17. The laser system with a multi-pass amplifier system as claimed in claim 16, wherein the radius of curvature of the curved mirror is configured such that the beam radius of at least one amplified output seed signal remains substantially constant when passing through at least one gain medium device.

18. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one of the first mirror and at least one second mirror is angled relative to the gain medium device.

19. The laser system having a multi-pass amplifier system as claimed in claim 1, wherein at least one first amplifier stage includes at least one first amplifier stage gain medium.

20. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one first amplifier stage gain medium comprises Nd:YVO4 material.

21. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one first amplifier stage gain medium is selected from the group consisting of: Nd: GdVO4, Nd: YAG, Nd: YLF, Nd: glass, Yb: YAG, Yb: KGW, Yb: CaF2, Yb: CALGO, Yb: Lu2O3, Yb: S-FAP, Yb: glass, semiconductor gain medium, and ceramic laser material.

22. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein the gain medium device located within at least one second amplifier stage comprises Nd:YVO4 material.

23. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein the gain medium device located within at least one second amplifier stage is selected from the group consisting of: Nd: GdVO4, Nd: YAG, Nd: YLF, Nd: glass, Yb: YAG, Yb: KGW, Yb: CaF2, Yb: CALGO, Yb: Lu2O3, Yb: S-FAP, Yb: glass, semiconductor gain media, and ceramic laser materials.

24. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one optical system includes at least one additional amplifier.

25. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one seed source is configured to output at least one seed signal with a wavelength of 1000 nm to 1100 nm.

26. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one seed source is configured to output at least one seed signal with a wavelength of 1064 nm.

27. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one seed source is configured to output at least one seed signal with a wavelength of 1030 nm.

28. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein the gain medium device comprises Nd:YVO4 material.

29. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein the gain medium device is selected from the group consisting of: Nd: GdVO4, Nd: YAG, Nd: YLF, Nd: glass, Yb: YAG, Yb: KGW, Yb: CaF2, Yb: CALGO, Yb: Lu2O3, Yb: S-FAP, Yb: glass, semiconductor gain medium, and ceramic laser material.

30. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one of the first mirror and at least one second mirror comprises a curved mirror.

31. The laser system with a multi-pass amplifier system as claimed in claim 30, wherein the radius of curvature of the curved mirror is configured such that the beam radius of at least one amplified output seed signal remains substantially constant when passing through at least one gain medium device.

32. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one of the first mirror and at least one second mirror is angled relative to the gain medium device.

33. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one optical system includes at least one additional amplifier.

34. The laser system with a multi-pass amplifier system as claimed in claim 1, wherein at least one parasitic signal comprises a Raman-generated signal.

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