Optical amplification device and optical amplification method

Abstract

The optical amplifier (1A) includes: a laser medium (2) that amplifies input light (L1) and generates output light (L2); an excitation light source (3) that supplies the laser medium (2) with excitation light (L3) used in amplifying the input light (L1); a resonator (4) that includes a pair of first optical elements (6A, 6B) that are arranged to be optically opposed to each other across the laser medium (2) so that generated light (L4) generated in the laser medium (2) due to the supply of the excitation light (L3) resonates; and an optical switch (5) that is arranged between the pair of first optical elements (6A, 6B) on the optical path of the resonator (4).

Description

Technical Field

[0001] The present disclosure relates to an optical amplification device and an optical amplification method. Background Art

[0002] In an optical amplifier device that amplifies and outputs light such as a pulsed laser, it is very important to efficiently extract the energy accumulated inside the amplifier such as a laser medium as laser light. However, it is difficult to completely extract the energy accumulated inside the amplifier during laser amplification, and most of the energy remaining in the amplifier after laser amplification is converted into heat energy. This heat energy can be removed by cooling the laser medium, but if there is a large amount of residual heat energy, the cooling device will become larger and the power consumption will increase.

[0003] To address such a problem, for example, in the optical amplifier device described in Patent Document 1, a light branching section composed of a beam splitter or the like is provided at a predetermined position on the optical path of the output optical system, and a part of the amplified light is branched to generate branched light. Furthermore, the branched light is made incident on the amplifier section at a time earlier than the return light of the output light, and the excitation energy remaining in the amplifier section after the input light is amplified is consumed by amplifying the branched light.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2004-221278 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] In the above optical amplifier device, it is required to efficiently consume the excitation energy remaining in the amplifier unit after the input light is amplified, and to suppress the conversion of the excitation energy into heat energy. In addition, when consuming the excitation energy, it is required to take measures not to affect the quality of the input light input to the amplifier unit and the output light after amplification by the amplifier unit.

[0009] The present disclosure is made to solve the above-mentioned problems, and its purpose is to provide an optical amplification device and an optical amplification method, which can effectively suppress the residual heat energy in the amplification part without affecting the quality of input light and output light.

[0010] Technical means of solving problems

[0011] An optical amplification device according to one aspect of the present disclosure includes: an amplifier section that amplifies input light and generates output light; an excitation section that supplies the amplifier section with excitation light used in amplifying the input light; a resonance section that includes a pair of first optical elements that are arranged to be optically opposed to each other with the amplifier section interposed therebetween, so that light generated in the amplifier section due to the supply of the excitation light resonates; and an optical switch section that is arranged between the pair of first optical elements on the optical path of the resonance section.

[0012] In the optical amplifier device, the excitation energy remaining in the amplifier unit after the input light is amplified is efficiently consumed by resonating the generated light generated in the amplifier unit due to the supply of the excitation light. Since the optical switch unit is used in the resonance of the generated light, the timing of causing the generated light to resonate can be easily adjusted. Therefore, the generated light can be resonated before the excitation energy remaining in the amplifier unit after the input light is amplified is converted into heat energy. Therefore, the optical amplifier device can suppress the conversion of the excitation energy into heat energy in the amplifier unit, and can avoid the large size and high power consumption of the cooling device attached to the amplifier unit. In addition, the optical amplifier device uses the generated light generated in the amplifier unit due to the supply of the excitation light to resonate, and can reduce the possibility that the resonance affects the quality of the input light and the output light, and does not need to configure an additional light source for resonance.

[0013] The pair of first optical elements may be composed of a high reflectivity mirror and a low reflectivity mirror. In this case, the generated light can be gradually guided out from the low reflectivity mirror as laser light to the outside. Thus, the generated light can be prevented from being converted into heat energy in the amplification unit.

[0014] The optical path of the resonance part may be different from the optical path of the input light. By distinguishing the optical path of the resonance part from the optical path of the input light, it is possible to more reliably prevent the resonance of the generated light from affecting the quality of the input light and the output light.

[0015] At least one pair of excitation parts may be arranged in a manner of being optically opposed to each other with the amplifying part therebetween, and a second optical element is arranged on the optical path between the excitation part and the amplifying part so that one of the excitation light and the generated light is transmitted and the other is reflected. By adopting such an arrangement of the excitation parts, it is possible to obtain output light having a beam profile with good symmetry. On the other hand, in the case where the excitation parts are optically opposed to each other, unexpected oscillations (parasitic oscillations) may occur due to repeated reflections of the generated light generated in the amplifying part between the pair of excitation parts. When parasitic oscillations occur, the excitation energy supplied to the amplifying part may be consumed before the input light is amplified. In response to this, by arranging a second optical element on the optical path between the excitation part and the amplifying part, it is possible to suppress repeated reflections of the generated light between the pair of excitation parts, thereby preventing the occurrence of parasitic oscillations.

[0016] The resonator may resonate the generated light after being reflected or transmitted by the second optical element. In this case, the optical path of the excitation light can be made consistent with the optical path of the resonator in the amplifier. Thus, the excitation energy remaining in the part where the optical path of the input light and the optical path of the excitation light are inconsistent in the amplifier can be efficiently consumed.

[0017] A pair of third optical elements that transmit one of the P-polarized light and the S-polarized light and reflect the other may be arranged on the optical path of the input light so as to sandwich the amplifying section, and the optical path of the resonance section may be at least partially the same as the optical path of the input light. In this case, at least a portion of the optical path of the input light and the optical path of the resonance section are shared, and the device structure can be simplified.

[0018] An optical amplification method according to one aspect of the present disclosure includes: an excitation step, in which excitation light is supplied to an amplifier to excite the amplifier; an amplification step, in which input light is supplied to the amplifier supplied with the excitation light, and the input light is amplified to generate output light; and a resonance step, in which an optical switch portion arranged between a pair of first optical elements constituting a resonance portion is used to cause light generated in the amplifier due to the supply of the excitation light to resonate between the pair of first optical elements.

[0019] In this optical amplification method, the excitation energy remaining in the amplifier section after the input light is amplified is efficiently consumed by causing the generated light generated in the amplifier section due to the supply of the excitation light to resonate. Since an optical switch section is used in the resonance of the generated light, the moment of causing the generated light to resonate can be easily adjusted. Therefore, the generated light can be resonated before the excitation energy remaining in the amplifier section after the input light is amplified is converted into heat energy. Thus, the optical amplification method can suppress the conversion of the excitation energy into heat energy in the amplifier section, and can avoid the large-scale and high power consumption of the cooling device attached to the amplifier section. In addition, the optical amplification method uses the generated light generated in the amplifier section due to the supply of the excitation light to resonate, which can reduce the possibility that the resonance affects the quality of the input light and the output light, and does not require the configuration of an additional light source for resonance.

[0020] The resonance step may be included after the amplification step. In this case, the resonance of the generated light can be used to effectively consume the excitation energy remaining in the amplifier after the input light is amplified. Thus, the conversion of the excitation energy into heat energy in the amplifier can be more reliably suppressed.

[0021] The optical switch section may be used to limit the resonance of the generated light in the excitation step and the amplification step. In this case, the excitation energy of the amplifier section can be prevented from being consumed by the resonance of the generated light in the excitation step and the amplification step. Thus, the possibility of the resonance affecting the quality of the output light can be reduced.

[0022] Effects of the Invention

[0023] According to the present disclosure, it is possible to efficiently suppress the residual heat energy in the amplification section without affecting the quality of input light and output light. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a diagram schematically showing the configuration of an optical amplifier device according to the first embodiment.

[0025] Figure 2 This is a flowchart showing an example of an optical amplification method using an optical amplifier device.

[0026] Figure 3 FIG. 1 is a diagram schematically showing the configuration of an optical amplifier device according to a second embodiment.

[0027] Figure 4 This diagram shows the relationship between the accumulation region of excitation energy and the consumption region where the excitation energy is consumed by resonance when the optical path of the excitation light and the optical path of the resonator do not coincide with each other.

[0028] Figure 5 This is a diagram showing the relationship between the accumulation region of excitation energy and the consumption region where the excitation energy is consumed by resonance when the optical path of the excitation light coincides with the optical path of the resonator.

[0029] Figure 6 It is a diagram showing the effect of the optical amplifier device disclosed in the present invention.

[0030] Figure 7 It is a diagram schematically showing the configuration of an optical amplifier device according to a third embodiment.

[0031] Figure 8 Yes means Figure 7 A schematic structural diagram of a modified example of .

[0032] Fig. 9 Yes means Figure 7 A schematic structural diagram of another modified example of . DETAILED DESCRIPTION

[0033] The preferred embodiments of the optical amplification device and the optical amplification method according to one aspect of the present disclosure are described in detail below with reference to the accompanying drawings.

[0034] [First embodiment]

[0035] Figure 1 1 is a schematic diagram showing the structure of an optical amplifier device according to the first embodiment. The optical amplifier device 1A shown in the figure is a device that amplifies input light L1 and outputs the obtained amplified light as output light L2. Figure 1As shown, the optical amplifier device 1A is configured to include a laser medium (amplifier section) 2 , an excitation light source (excitation section) 3 , a resonator (resonator section) 4 , and an optical switch (optical switch section) 5 .

[0036] The laser medium 2 is a part that amplifies the input light L1 to generate the output light L2. The input light L1 to be amplified is also called a seed laser, and is supplied to the laser medium 2 through the first optical path M1. As a light source (not shown) that outputs the input light L1, for example, a solid laser, a fiber laser, a semiconductor laser, etc. can be listed. The wavelength of the input light L1 output from the light source is, for example, 1030nm. The laser medium 2 is composed of a substance that amplifies light by generating stimulated radiation faster than light absorption. As the laser medium 2, for example, Yb:YAG, Nd:YAG, Nd:glass, Yb:glass, Nd:YLF, Yb:YLF, Ti:sapphire, Er:Y 2 O 3 、Er:YAG、Ho:YAG、Er:YVO 4 、Yb:YVO 4 、Nd:YVO 4 , Tm:YAG, Tm:YLF, etc. The laser medium 2 is placed in a vacuum container (not shown) and is cooled to a low temperature of about -200°C to 10°C. The laser medium 2 may be cooled to about 10°C to 30°C by water or the like.

[0037] The excitation light source 3 is a light source that supplies the laser medium 2 with the excitation light L3 used in amplifying the input light L1. As the excitation light source 3, for example, a semiconductor laser can be used. In the present embodiment, the wavelength of the excitation light L3 emitted from the excitation light source 3 is, for example, 940 nm. The excitation light L3 is supplied to the laser medium 2 through a second optical path M2 that is different from the first optical path M1 that supplies the input light L1, and excitation energy is supplied to the laser medium 2. When the input light L1 is supplied to the laser medium 2 in a state in which the excitation light L3 is supplied, the input light L1 is amplified in the laser medium 2, and the output light L2 is generated from the amplified input light L1. The output light L2 is output from the laser medium 2 coaxially with the first optical path M1 that supplies the input light L1, and is led out to the outside of the optical amplifier device 1A.

[0038] The resonator 4 is a part that resonates the light (hereinafter referred to as the generated light L4) generated in the laser medium 2 due to the supply of the excitation light L3. The generated light L4 is mainly fluorescence, but there is also a case where the generated light L4 is composed of light other than fluorescence such as phosphorescence. In the present embodiment, the generated light L4 is, for example, fluorescence with a wavelength of 1030nm. Usually, the generated light L4 is emitted in all directions with the position where the excitation light L3 incident on the laser medium 2 is absorbed as the center. At this time, the excitation light L3 is absorbed exponentially with respect to the distance propagated in the laser medium 2.

[0039] The resonator 4 is composed of, for example, a pair of first optical elements 6A and 6B arranged to be optically opposed to each other with the laser medium 2 interposed therebetween. Here, the first optical element 6A is a high-reflectivity mirror 7 having a relatively high reflectivity for the generated light L4, and the first optical element 6B is a low-reflectivity mirror 8 having a relatively low reflectivity for the generated light. Among the generated light L4 generated in the laser medium 2, a part of the components propagating in a direction consistent with the third optical path M3 of the resonator 4 is repeatedly reflected between the high-reflectivity mirror 7 and the low-reflectivity mirror 8, and each reflection passes through the laser medium 2, thereby consuming the excitation energy remaining in the laser medium 2 after the input light L1 is amplified. A part of the components of the generated light L4 becomes laser light due to repeated reflections between the high-reflectivity mirror 7 and the low-reflectivity mirror 8, and is gradually led out of the optical amplifier device 1A from the side of the low-reflectivity mirror 8.

[0040] In addition, the remaining components of the generated light L4 generated in the laser medium 2 that are not incident on the resonator 4 are repeatedly reflected, scattered, and absorbed by the holder, light shielding body, etc. arranged around it. A part of the remaining components may be converted into heat energy by returning to the laser medium 2 or irradiating other elements. In addition, an element into which a part of the generated light L4 guided from the low reflectivity mirror 8 side is incident may be arranged outside the optical amplifier device 1A, and a part of the generated light L4 is converted into heat energy in the element.

[0041] The optical switch 5 is a part for switching the optical loss in the third optical path M3 of the resonator 4. The optical switch 5 is arranged between a pair of first optical elements 6A and 6B in the third optical path M3. Figure 1 In the example of , the optical switch 5 is arranged between the high reflectivity mirror 7 and the laser medium 2 in the third optical path M3. As the optical switch 5, for example, an electro-optic modulator such as a Pockels cell, an acousto-optic modulator such as a Bragg cell, a magneto-optic modulator such as a Faraday rotator, a polarization element such as a wavelength plate and a polarizer, etc. can be used. In addition, the optical switch 5 can also be a high-speed mechanical shutter, a liquid crystal element, a spatial light modulation element, a supersaturated absorption element (Cr-doped crystal, Cr-doped ceramic, colored glass, semiconductor material), etc.

[0042] The ON / OFF switching of the optical switch 5 is performed by a control unit (not shown). When the optical switch 5 is ON, the optical loss in the third optical path M3 is reduced, and the resonance of the generated light L4 in the resonator 4 can occur. When the optical switch 5 is OFF, the optical loss in the third optical path M3 is increased, and the generated light L4 in the resonator 4 cannot resonate. From the viewpoint of preventing the amplification efficiency of the input light L1 in the laser medium 2 from being reduced, the control unit turns the optical switch 5 OFF at the moment when the input light L1 is amplified by the laser medium 2. After the laser medium 2 amplifies the input light L1, the control unit switches the optical switch 5 from OFF to ON in the order of nanoseconds to microseconds. As a result, before the excitation energy remaining in the laser medium 2 after the amplification of the input light L1 is converted into heat energy, the generated light L4 is resonated in the resonator 4, and the excitation energy is consumed by the resonance of the generated light L4.

[0043] Figure 2 1 is a flowchart showing an example of an optical amplification method using an optical amplifier device. As shown in the figure, the optical amplification method includes an excitation step (step S01), an amplification step (step S02), and a resonance step (step S03).

[0044] In the excitation step and the amplification step, the optical switch 5 is OFF, and the generated light L4 generated in the laser medium 2 is restricted from resonating in the resonator 4. In the excitation step, the excitation light L3 is supplied to the laser medium 2 from the excitation light source 3 to excite the laser medium 2. In the amplification step after the excitation step, the input light L1 is supplied to the laser medium 2 excited by the excitation light L3. As a result, the input light L1 is amplified in the laser medium 2, and the output light L2 is generated from the amplified input light L1. The output light L2 is output from the laser medium 2 coaxially with the first optical path M1 supplied with the input light L1, and is led out to the outside of the optical amplifier device 1A.

[0045] In the resonance step, after the input light L1 is amplified by the laser medium 2 in the amplification step, the optical switch 5 is switched from ON to ON in the order of nanoseconds to microseconds. As a result, among the generated light L4 generated in the laser medium 2 in the amplification step, a part of the components propagating in the direction consistent with the third optical path M3 of the resonator 4 is repeatedly reflected between the high reflectivity mirror 7 and the low reflectivity mirror 8, and each reflection passes through the laser medium 2, thereby consuming the excitation energy remaining in the laser medium 2 after the input light L1 is amplified. A part of the components of the generated light L4 becomes laser light due to repeated reflection between the high reflectivity mirror 7 and the low reflectivity mirror 8, and is gradually led out of the optical amplifier device 1A from the side of the low reflectivity mirror 8.

[0046] As described above, in the optical amplifier device 1A and the optical amplification method, by resonating the generated light L4 generated in the laser medium 2 due to the supply of the excitation light L3, the excitation energy remaining in the laser medium 2 after the input light L1 is amplified can be efficiently consumed. Since the optical switch 5 is used for the resonance of the generated light L4, the timing of resonating the generated light L4 can be easily adjusted. Therefore, the generated light L4 can be resonated before the excitation energy remaining in the laser medium 2 after the input light L1 is amplified is converted into heat energy. Therefore, the optical amplifier device 1A can suppress the conversion of the excitation energy into heat energy in the laser medium 2, and can avoid the increase in size and power consumption of the cooling device attached to the laser medium 2. In addition, the optical amplifier device 1A uses the generated light L4 generated in the laser medium 2 due to the supply of the excitation light L3 to resonate, and can reduce the possibility that the resonance affects the quality of the input light L1 and the output light L2, and does not need to configure an additional light source for resonance.

[0047] In addition, in the optical amplifier device 1A, the pair of first optical elements 6A and 6B included in the resonator 4 are composed of a high-reflectivity mirror 7 and a low-reflectivity mirror 8. In the case where both of the pair of first optical elements 6A and 6B are composed of high-reflectivity mirrors, it is expected that a part of the components of the generated light L4 passes through the laser medium too many times before being led out of the resonator 4, and a part of it is converted into heat energy in the laser medium 2. In contrast, by making one of the pair of first optical elements 6A and 6B a low-reflectivity mirror 8, the generated light L4 can be gradually led out of the low-reflectivity mirror 8 as laser light. Therefore, it is possible to suppress the generated light L4 from being converted into heat energy in the laser medium 2.

[0048] In the optical amplifier device 1A, the third optical path M3 of the resonator 4 is different from the first optical path M1 of the input light L1. By distinguishing the optical path of the resonator 4 from the optical path of the input light L1 in this way, it is possible to more reliably prevent the resonance of the generated light L4 from affecting the quality of the input light L1 and the output light L2.

[0049] [Second embodiment]

[0050] Figure 3 1 is a schematic diagram showing the configuration of an optical amplifier device according to the second embodiment. As shown in the figure, in the optical amplifier device 1B according to the second embodiment, the arrangement configuration of the excitation light source 3 and the resonator 4 is different from that of the first embodiment.

[0051] More specifically, in the optical amplifier device 1B, at least a pair of excitation light sources 3 are arranged so as to be optically opposed to each other with the laser medium 2 interposed therebetween. Figure 3In the example, the optical amplifier device 1B includes a pair of excitation light sources 3A, 3A optically opposed to each other via a laser medium 2, and a pair of excitation light sources 3B, 3B optically opposed to each other via the laser medium 2 on an axis different from that of the pair of excitation light sources 3A, 3A.

[0052] The second optical path M2A of the excitation light L3 from the excitation light sources 3A and 3A to the laser medium 2, and the second optical path M2B of the excitation light L3 from the excitation light sources 3B and 3B to the laser medium 2 are both optical paths different from the first optical path M1 for supplying the input light L1. In addition, the second optical path M2A and the second optical path M2B are line-symmetrical about the first optical path M1.

[0053] A second optical element 9 is disposed on the optical path between the excitation light sources 3A, 3A and the laser medium 2 and on the optical path between the excitation light sources 3B, 3B and the laser medium 2, respectively, so as to transmit one of the excitation light L3 and the generated light L4 and reflect the other. The second optical element 9 is, for example, a wavelength selective reflector 10 formed by coating a dielectric multilayer film. Figure 3 In the example, the structure is to transmit the excitation light L3 and reflect the generated light L4.

[0054] The optical switch 5 and the high reflectivity mirror 7A are arranged on the optical path of the generated light L4 reflected by one wavelength selective mirror 10, and the low reflectivity mirror 8A is arranged on the optical path of the generated light L4 reflected by the other wavelength selective mirror 10. In the optical amplifier 1B, in the third optical path M3A of the resonator 4A constituted by the high reflectivity mirror 7A and the low reflectivity mirror 8A, the optical path between the pair of wavelength selective mirrors 10, 10 across the laser medium 2 is the same as the second optical path M2A of the excitation light L3, while the optical paths between the one wavelength selective mirror 10 and the high reflectivity mirror 7A and between the other wavelength selective mirror 10 and the low reflectivity mirror 8A are different from the second optical path M2A of the excitation light L3. Similarly, in the third optical path M3B of the resonator 4B formed by the high-reflectivity mirror 7B and the low-reflectivity mirror 8B, the optical path between a pair of wavelength-selective mirrors 10, 10 separated by the laser medium 2 is the same as the second optical path M2B of the excitation light L3, while the optical paths between the wavelength-selective mirror 10 and the high-reflectivity mirror 7B on one side and between the wavelength-selective mirror 10 and the low-reflectivity mirror 8B on the other side are different from the second optical path M2B of the excitation light L3.

[0055] In such an optical amplifier device 1B, the same effects as those of the optical amplifier device 1 of the first embodiment can be achieved, and the residual heat energy in the laser medium 2 can be effectively suppressed without affecting the quality of the input light L1 and the output light L2. In addition, in the optical amplifier device 1B, by arranging the excitation light source 3 in an optically opposed manner with the laser medium 2 interposed therebetween, the output light L2 having a beam profile with good symmetry can be obtained.

[0056] On the other hand, when the excitation light source 3 is optically opposed, unexpected oscillations (parasitic oscillations) may occur due to repeated reflections of the generated light L4 in the laser medium 2 between a pair of excitation light sources 3, 3 (for example, between the emission end faces of the excitation light source 3). When parasitic oscillations occur, the excitation energy supplied to the laser medium 2 may be consumed before the input light L1 is amplified. In particular, when the distance between the excitation light source 3 and the laser medium 2 is reduced in order to obtain amplified light with a large output, and when a stacked semiconductor laser with a relatively large metal heat sink is used as the excitation light source 3, parasitic oscillations between the excitation light sources 3, 3 are easily generated.

[0057] In this regard, the optical amplifier device 1B can prevent the generated light L4 from being incident on the excitation light source 3 even when the excitation light source 3 is arranged in an optically opposed manner across the laser medium 2 by disposing the second optical element 9 on the optical path between the excitation light source 3 and the laser medium 2. Thus, it is possible to suppress the generated light L4 from being repeatedly reflected between the pair of excitation light sources 3, 3, and prevent the generation of parasitic oscillation.

[0058] In addition, in the optical amplifier device 1B, the resonator 4 resonates the generated light L4 after being reflected by the second optical element 9. As a result, the second optical path M2 of the excitation light L3 can be made consistent with the third optical path M3 of the resonator 4 in the laser medium 2. Therefore, the resonator 4 can efficiently consume the excitation energy remaining in the region consistent with the second optical path M2 of the excitation light L3 in the laser medium 2.

[0059] Figure 4 and Figure 5 are diagrams showing the relationship between the accumulation area of ​​excitation energy and the consumption area of ​​excitation energy through resonance. In these diagrams, the distribution of excitation energy is represented by grayscale. For example Figure 4 As shown in FIG. 1 , when there is a portion in the laser medium 2 where the first optical path M1 of the input light L1 and the second optical path M2 of the excitation light L3 do not coincide, it can be expected that excitation energy remains in the region R0 that does not coincide with the third optical path M3 among the regions R where excitation energy is accumulated in the laser medium 2. In particular, the amount of excitation energy accumulated in the region R0 is likely to increase on the incident side of the excitation light L3, and it is preferable to consume the excitation energy of this portion efficiently. In view of this, in the optical amplifier 1B, as shown in FIG. Figure 5As shown, since the second optical path M2 of the excitation light L3 in the laser medium 2 is consistent with the third optical path M3 of the resonator 4, even if there is a part where the first optical path M1 of the input light L1 and the second optical path M2 of the excitation light L3 are inconsistent, the excitation energy remaining in the area R can be efficiently consumed.

[0060] Figure 6 1 is a diagram showing the effect of the optical amplifier device disclosed in the present invention. The diagram shows the ratio of the energy supplied to the laser medium as optical radiation and the energy as thermal radiation for the comparative example and the embodiment of the optical amplifier device. Figure 3 The structure of the optical amplifier of the second embodiment shown is the same as that of the optical amplifier of the second embodiment, and the comparative example is an optical amplifier obtained by removing the resonator, the optical switch and the second optical element from the structure of the optical amplifier of the second embodiment. The excitation energy of the excitation light to the laser medium is 450J.

[0061] In the comparative example, Figure 6 As shown in (a), with respect to the excitation energy of 450 J (100%), the energy as optical radiation when the input light is amplified is 54 J (12%), and the energy as thermal radiation is 45 J (10%). In addition, the excitation energy remaining in the laser medium after the input light is amplified is 351 J (78%), of which 22.5 J (5%) is optical radiation and the remaining 328.5 J (73%) is thermal radiation. That is, in the comparative example, with respect to the excitation energy of 450 J, a total of 373.5 J (83%) becomes thermal energy.

[0062] In this regard, in the embodiment, Figure 6 As shown in (b), the energy as light and heat radiation when the input light is amplified, and the energy as light radiation in the excitation energy of the laser medium after the input light is amplified are the same ratio as the comparative example, but the 328.5J of energy as heat radiation in the excitation energy of the laser medium after the input light is amplified is consumed as light energy before being converted into heat energy. Therefore, the energy as heat radiation in the embodiment is only 45J (10%). That is, the embodiment can extract 90% of the excitation energy as light, and the heat generation can be reduced to about 1 / 8 compared with the comparative example.

[0063] [Third Embodiment]

[0064] Figure 7 As shown in the figure, the optical amplifier 1C of the third embodiment is different from the first embodiment in that the third optical path M3 of the resonator 4 is at least partially identical to the first optical path M1 of the input light L1.

[0065] More specifically, in the optical amplifier 1C, a pair of third optical elements 11, 11 are arranged on the first optical path M1 of the input light L1 so as to sandwich the laser medium 2. The third optical element 11 is, for example, a polarization beam splitter 12. Figure 7 In the example, the structure is to transmit P-polarized light and reflect S-polarized light. A low-reflectivity mirror 8 is arranged on the optical path of the generated light L4 reflected by the polarization beam splitter 12 on one side, and an optical switch 5 and a high-reflectivity mirror 7 are arranged on the optical path of the generated light L4 reflected by the polarization beam splitter 12 on the other side.

[0066] In the optical amplifier 1C, the optical path between a pair of polarization beam splitters 12, 12 separated by the laser medium 2 in the third optical path M3 of the resonator 4 is the same as the first optical path M1 of the input light L1, while the optical paths between the polarization beam splitter 12 and the high reflectivity mirror 7 on one side and between the polarization beam splitter 12 and the low reflectivity mirror 8 on the other side are different from the first optical path M1 of the input light L1.

[0067] The optical amplifier 1C supplies P-polarized input light L1 to the laser medium 2. The P-polarized input light is transmitted through one polarization beam splitter 12 and supplied to the laser medium 2, and the output light L2 amplified by the laser medium 2 is transmitted through the other polarization beam splitter 12 and guided out of the optical amplifier 1C. In the resonator 4, the S-polarized component of the generated light L4 generated in the laser medium 2 resonates, consuming the excitation energy remaining in the laser medium 2 after the input light L1 is amplified.

[0068] In such an optical amplifier device 1C, the same effects as those of the optical amplifier device 1 of the first embodiment can be achieved, and the residual heat energy in the laser medium 2 can be efficiently suppressed without affecting the quality of the input light L1 and the output light L2. In addition, in the optical amplifier device 1C, a pair of third optical elements 11, 11 are arranged on the first optical path M1 of the input light L1 so as to sandwich the laser medium 2, and the third optical path M3 of the resonator 4 is at least partially the same as the first optical path M1 of the input light L1. As a result, the first optical path M1 of the input light L1 and at least a portion of the third optical path M3 of the resonator 4 are shared, so that the device structure can be simplified.

[0069] The optical amplifier device 1C can adopt other modifications. Figure 8 In the example, the configuration relationship between the first optical path M1 of the input light L1 and the third optical path M3 of the resonator 4 is as follows: Figure 7 The opposite is true. That is, Figure 8In the example, the S-polarized input light L1 is reflected by one polarization beam splitter 12 and supplied to the laser medium 2, and the output light L2 amplified by the laser medium 2 is reflected by the other polarization beam splitter 12 and guided to the outside of the optical amplifier 1C. In the resonator 4, the P-polarized component of the generated light L4 generated in the laser medium 2 is transmitted through the polarization beam splitters 12, 12 and resonates, consuming the excitation energy remaining in the laser medium 2 after the input light L1 is amplified.

[0070] In addition, Fig. 9 In the example, the second optical path M2 of the excitation light L3 is Figure 7 The example is different. Fig. 9 In the example, a wavelength selective reflector 13 that reflects the excitation light L3 and transmits the input light L1 and the generated light L4 is arranged on the optical path between the laser medium 2 and one of the polarization beam splitters 12. Thus, the excitation light L3 supplied from the excitation light source 3 is reflected on the wavelength selective reflector 10 and is incident on the laser medium 2 coaxially with the first optical path M1 of the input light L1 and the third optical path M3 of the resonator 4.

[0071] In such a modified example, the same effects as those of the optical amplifier device 1A of the first embodiment can be achieved, and the residual heat energy in the laser medium 2 can be effectively suppressed without affecting the quality of the input light L1 and the output light L2. In addition, the first optical path M1 of the input light L1 and at least a part of the third optical path M3 of the resonator 4 are shared, so the device structure can be simplified.

[0072] [Modifications]

[0073] The present disclosure is not limited to the above-mentioned embodiments. For example, in the above-mentioned embodiments, the resonator 4 is formed by using the high-reflectivity mirror 7 and the low-reflectivity mirror 8, but an optical attenuation device such as an optical shutter may be arranged on the third optical path M3 of the resonator 4. In this case, after the generated light L4 is resonated for a certain period of time, the generated light L4 can be attenuated by the optical attenuation device, thereby cutting off the generated light L4 inside the device.

[0074] Description of Reference Numerals

[0075] 1A~1C...optical amplifying device, 2...laser medium (amplifying part), 3, 3A, 3B...excitation light source (excitation part), 4, 4A, 4B...resonator (resonating part), 5...optical switch (optical switch part), 6A, 6B...first optical element, 7...high reflectivity mirror, 8...low reflectivity mirror, 9...second optical element, 11...third optical element, L1...input light, L2...output light, L3...excitation light, L4...generated light.

Claims

1. An optical amplification device, comprising: a light source that emits input light; an amplifying unit, which amplifies the input light and generates output light; an excitation unit that supplies the amplification unit with excitation light used in amplifying the input light; a resonance section including a pair of first optical elements arranged to be optically opposed to each other with the amplifying section interposed therebetween, and causing the generated light generated in the amplifying section due to the supply of the excitation light to resonate; and an optical switch section disposed between the pair of first optical elements on an optical path of the resonator section, The optical path of the resonator is different from the optical path of the input light. The switching of the optical switch unit is performed by the control unit. The control unit turns OFF the optical switch unit at the moment of amplifying the input light, and switches the optical switch unit from OFF to ON after amplifying the input light, so as to cause the generated light to resonate in the resonance unit before the excitation energy remaining in the amplifier unit after amplification of the input light is converted into heat energy.

2. The optical amplification device according to claim 1, wherein: The pair of first optical elements is composed of a high-reflectivity mirror and a low-reflectivity mirror.

3. The optical amplification device according to claim 1 or 2, wherein: At least one pair of the excitation parts are arranged in an optically opposed manner across the amplification part. A second optical element is disposed on an optical path between the excitation section and the amplification section so as to transmit one of the excitation light and the generated light and reflect the other.

4. The optical amplifying device according to claim 3, wherein: The resonance part resonates the generated light after being reflected or transmitted by the second optical element.

5. The optical amplification device according to claim 1 or 2, wherein: A pair of third optical elements are arranged on the optical path of the input light so as to sandwich the amplifying section, and transmit one of the P-polarized light and the S-polarized light and reflect the other. The optical path of the resonance section is identical to at least a portion of the optical path of the input light.

6. A method for light amplification, comprising: an excitation step of supplying excitation light to the amplifying part to excite the amplifying part; an amplification step of supplying input light to the amplification unit supplied with the excitation light, and amplifying the input light to generate output light; and a resonance step, wherein the resonance of the generated light generated in the amplifier due to the supply of the excitation light occurs between the pair of first optical elements by using an optical switch portion disposed between the pair of first optical elements constituting the resonance portion, The input light is emitted from a light source, The optical path of the resonator is different from the optical path of the input light. The optical switch unit is turned OFF during the amplification step, and after the amplification step, the optical switch unit is switched from OFF to ON, so that the generated light resonates in the resonance unit before the excitation energy remaining in the amplification unit after the amplification of the input light is converted into heat energy.

7. The optical amplification method according to claim 6, wherein: The resonating step is included after the amplifying step.

8. The optical amplification method according to claim 6 or 7, wherein: The optical switch section is used to limit the resonance of the generated light in the exciting step and the amplifying step.

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