Laser gain medium and visible band solid laser

Abstract

The present invention discloses a laser gain medium and a visible band solid laser, which belongs to the technical field of solid lasers and can solve the existing Tb 3+ The solid laser output power is low and the pump light source is expensive. 3+ ions and Dy 3+ Ion materials are used as laser gain media, where Tb 3+ ions as active ions, Dy 3+ ions as sensitizing ions, Tb 3+ The pumping band of the laser material is converted from 488nm to 450nm, solving the problem of existing Tb 3+ Solid-state lasers cannot use commercial high-power 450nm band semiconductor lasers as pump sources, effectively reducing the cost of pump light sources and increasing Tb 3+ Output performance of solid-state lasers.

Description

Technical Field

[0001] The invention relates to a laser gain medium and a visible waveband solid laser, belonging to the technical field of solid lasers. Background Art

[0002] Visible light band solid lasers can be widely used in optical communications, biomedicine and information storage. 3+ ) has a rich energy level structure, such as Figure 1 As shown, using Tb 3+ Doped materials are used as laser gain media, using their 5 D4→ 7 F5 and 5 D4→ 7 The F4 energy level transition can achieve laser output in the 540nm green band and the 590nm yellow band, respectively. This solid-state laser has the advantages of miniaturization and compact structure, high working stability, and important application value.

[0003] Tb 3+ Main selection of doped laser materials 7 F6 → 5 The energy level transition of D4 is used as the pump channel, and the pump wavelength is located near 488nm. At present, the pump light sources in the 488nm band are mainly GaN semiconductor lasers and frequency-doubled optically pumped semiconductor lasers (2ω-OPSL). However, the 488nm band GaN semiconductor lasers are expensive and have low output power (hundreds of milliwatts), while the 488nm band 2ω-OPSL lasers are complex in structure, large in size and expensive. Therefore, the lack of cheap high-power pump light sources has seriously limited the development of Tb 3+ Output performance and practical application value of visible band lasers. Summary of the Invention

[0004] The present invention provides a laser gain medium and a visible band solid laser, which can solve the existing Tb 3+ The solid-state laser has low output power and the pump source is expensive.

[0005] In one aspect, the present invention provides a laser gain medium comprising Tb 3+ ions and Dy 3+ ion materials, and Tb 3+ ions as active ions, Dy 3+ ions as sensitizing ions.

[0006] Optionally, the laser gain medium is Tb-doped 3+ ions and Dy 3+ Ion co-doped materials;

[0007] Preferably, the laser gain medium is Tb 3+ ions and Dy 3+ Ion-doped crystals, glasses or transparent ceramics;

[0008] Preferably, the crystal is LiLuF4, LiYF4, KY3F 10 , BaY2F8, BaLu2F8, LaF3, CaF2, Y3Al5O 12 , one of YAl3(BO3)4, KGd(WO4)2 or YVO4;

[0009] Preferably, the glass is fluoride glass;

[0010] Preferably, the transparent ceramic is CaF2 or Y3Al5O 12 .

[0011] Optionally, the laser gain medium is doped with Dy 3+ Tb ions 3+ Self-activating materials;

[0012] Preferably, the laser gain medium is doped with Dy 3+ Tb ions 3+ self-activated crystals or transparent ceramics;

[0013] Preferably, the self-activated crystal is LiTbF4, TbF3, KTb3F 10 、BaTb2F8、Tb3Al5O 12 , one of TbAl3(BO3)4, KTb(WO4)2 or TbVO4;

[0014] Preferably, the transparent ceramic is Tb3Al5O 12 .

[0015] Optionally, the Tb 3+ The doping concentration of ions is greater than or equal to 10at.%, and the Dy 3+ The doping concentration of the ions is less than or equal to 5 at.%.

[0016] On the other hand, the present invention also provides a visible band solid laser, comprising a pump light source, an input mirror, an output mirror and any one of the above-mentioned laser gain media;

[0017] The laser gain medium is arranged on the outgoing light path of the pump light source;

[0018] The input mirror and the output mirror form a laser resonant cavity, and the laser gain medium is located in the laser resonant cavity;

[0019] The pump light source is a semiconductor laser, which is used to emit laser light in the 440nm-460nm band;

[0020] The laser gain medium is used for emitting visible solid laser in the 540nm band or the 590nm band under the excitation of the pump light source.

[0021] Optionally, the transmittance T of the input mirror is ≥80% in the 450nm band and ≤0.5% in the 520-600nm band;

[0022] The output mirror has a transmittance of 0.5%≤T≤10% in the 520-600nm band.

[0023] Optionally, the solid-state laser further includes a Q-switching element or a mode-locking element in the visible band, and the Q-switching element or the mode-locking element is arranged between the laser gain medium and the output mirror;

[0024] Preferably, the Q-switching element is an acousto-optic Q-switching element;

[0025] Preferably, the Q-switching element is Cr 4+ :YAG or Co 2+ :MgAl2O4 crystals;

[0026] Preferably, the Q-switching element or mode-locking element is graphene, MoS2, black phosphorus or Bi2Se3;

[0027] Preferably, the Q-switching element or mode-locking element is a semiconductor saturable absorber mirror;

[0028] Preferably, the semiconductor saturable absorber mirror serves as the output mirror while serving as the Q-switching element or the mode-locking element.

[0029] Optionally, the laser includes a nonlinear optical element in the visible band, the cutting angle of the nonlinear optical element is a frequency-doubled phase matching angle of the fundamental laser wavelength emitted by the laser gain medium; the nonlinear optical element is arranged between the laser gain medium and the output mirror;

[0030] The transmittance of the input mirror in the 450nm band is T ≥ 80%, and the transmittance in the 520-600nm band and the double frequency band is T ≤ 0.5%; the transmittance of the output mirror in the 520-600nm band is T ≤ 0.5%, and the transmittance in the double frequency band is T ≥ 70%;

[0031] Preferably, the nonlinear optical element is an LBO or β-BBO crystal.

[0032] Optionally, the nonlinear optical element is arranged between the Q-switching element or the mode-locking element and the output mirror.

[0033] Optionally, the solid-state laser further includes a wavelength tuning element in the visible band; the wavelength tuning element is arranged between the laser gain medium and the output mirror;

[0034] Preferably, the wavelength tuning element is a birefringent filter, a grating or a prism.

[0035] The beneficial effects that the present invention can produce include:

[0036] The present invention utilizes 3+ ions and Dy 3+ Ion materials are used as laser gain media, where Tb 3+ ions as active ions, Dy 3+ ions as sensitizing ions, Tb 3+ The pumping band of the laser material is converted from 488nm to 450nm, solving the problem of existing Tb 3+ Solid-state lasers cannot use commercial high-power 450nm band semiconductor lasers as pump sources, effectively reducing the cost of pump light sources and increasing Tb 3+ Output performance of solid-state lasers. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The laser gain medium of the present invention is doped with Tb 3+ ions and Dy 3+ Diagram of the working principle of visible band laser of ion co-doped materials. DETAILED DESCRIPTION

[0038] The present invention is described in detail below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0039] like Figure 1 As shown, Dy 3+ Ionic 6 H 15 / 2 → 4 I 15 / 2 Energy level transition is an effective pump channel, and the pump wavelength is around 450nm, so it can be effectively excited by the currently relatively cheap commercial high-power 450nm band semiconductor laser. 3+ After the ions are excited by the 450nm wavelength light, they are 6 H 15 / 2 Jump to 4 I 15 / 2 The multiple states are then rapidly populated by the multiphonon relaxation process. 4 F 9 / 2 Multiple states. Due to Dy 3+ ion 4 F 9 / 2 Multiplets and Tb3+ ion 5 The energy levels of the D4 multiple states are close, so Tb can be transferred efficiently. 3+ Ion population 5 D4 multiplex, then through 5 D4→ 7 F5 and 5 D4→ 7 The F4 energy level transition realizes laser output in the 540nm green band and the 590nm yellow band respectively.

[0040] On the one hand, an embodiment of the present invention provides a laser gain medium, wherein the laser gain medium comprises Tb 3+ ions and Dy 3+ ion materials, and Tb 3+ ions as active ions, Dy 3+ ions as sensitizing ions.

[0041] The Tb 3+ The doping concentration of ions is greater than or equal to 10at.%, and the Dy 3+ The doping concentration of the ions is less than or equal to 5 at.%.

[0042] Compared with the solutions in the prior art, the advantages of this application are: 3+ ions and Dy 3+ Ion materials are used as laser gain media, where Tb 3+ ions as active ions, Dy 3+ ions as sensitizing ions, Tb 3+ The pumping band of the laser material is converted from 488nm to 450nm, solving the problem of existing Tb 3+ Solid-state lasers cannot use commercial high-power 450nm band semiconductor lasers as pump sources, effectively reducing the cost of pump light sources and increasing Tb 3+ Output performance of solid-state lasers.

[0043] In the embodiment of the present invention, the laser gain medium is Tb-doped 3+ ions and Dy 3+ Ion co-doped materials.

[0044] Specifically, the laser gain medium is Tb 3+ ions and Dy 3+ Ion co-doped crystal, glass or transparent ceramic. The crystal is LiLuF4, LiYF4, KY3F 10 , BaY2F8, BaLu2F8, LaF3, CaF2, Y3Al5O 12, YAl3(BO3)4, KGd(WO4)2 or YVO4; the glass is fluoride glass; the transparent ceramic is CaF2 or Y3Al5O 12 .

[0045] In another embodiment of the present invention, the laser gain medium is doped with Dy 3+ Tb ions 3+ Self-activating material.

[0046] Specifically, the laser gain medium is doped with Dy 3+ Tb ions 3+ Self-activated crystal or transparent ceramic. The self-activated crystal is LiTbF4, TbF3, KTb3F 10 、BaTb2F8、Tb3Al5O 12 , TbAl3(BO3)4, KTb(WO4)2 or TbVO4; the transparent ceramic is Tb3Al5O 12 .

[0047] Another embodiment of the present invention provides a visible-band solid-state laser, comprising a pump light source, an input mirror, an output mirror, and any of the aforementioned laser gain media. The laser gain medium is disposed in the output optical path of the pump light source; the input mirror and the output mirror form a laser resonant cavity, and the laser gain medium is located within the laser resonant cavity; the pump light source is a semiconductor laser configured to emit laser light in the 440nm-460nm band; and the laser gain medium is configured to emit visible solid-state laser light in the 540nm or 590nm band under the excitation of the pump light source.

[0048] Specifically, the transmittance of the input mirror in the 450nm band is T≥80%, and the transmittance in the 520-600nm band is T≤0.5%; the transmittance of the output mirror in the 520-600nm band is 0.5%≤T≤10%.

[0049] In another embodiment of the present invention, the solid-state laser further includes a Q-switching element or a mode-locking element in the visible band, and the Q-switching element or the mode-locking element is disposed between the laser gain medium and the output mirror.

[0050] The Q-switching element is an acousto-optic Q-switching element.

[0051] The Q-switching element is Cr 4+ :YAG or Co 2+ :MgAl2O4 crystals.

[0052] The Q-switching element or mode-locking element is graphene, MoS2, black phosphorus or Bi2Se3.

[0053] The Q-switching element or the mode-locking element is a semiconductor saturable absorption mirror.

[0054] The semiconductor saturable absorber mirror serves as the output mirror while serving as the Q-switching element or the mode-locking element.

[0055] The laser further comprises a nonlinear optical element in the visible band, wherein the cutting angle of the nonlinear optical element is the frequency-doubled phase matching angle of the fundamental laser wavelength emitted by the laser gain medium; the nonlinear optical element is arranged between the laser gain medium and the output mirror.

[0056] The transmittance T of the input mirror in the 450nm band is ≥80%, and the transmittance T in the 520-600nm band and the frequency doubling band is ≤0.5%; the transmittance T of the output mirror in the 520-600nm band is ≤0.5%, and the transmittance T in the frequency doubling band is ≥70%; the nonlinear optical element is an LBO or β-BBO crystal.

[0057] The nonlinear optical element is arranged between the Q-switching element or the mode-locking element and the output mirror.

[0058] In another embodiment of the present application, the solid-state laser further includes a wavelength tuning element in the visible band, the wavelength tuning element being disposed between the laser gain medium and the output mirror, and the wavelength tuning element being a birefringent filter, a grating, or a prism.

[0059] Four specific embodiments are provided below to illustrate the technical solution of the present invention in detail.

[0060] Example 1

[0061] In the first embodiment of the present invention, the pump light source is a 450nm semiconductor laser, and the laser gain medium is Tb 3+ ions, Dy 3+ Ion co-doped LiLuF4 crystal; 450nm semiconductor laser pumping Tb 3+ ions, Dy 3+ The ion-co-doped LiLuF4 crystal achieves 544nm green band and 272nm frequency-doubled laser output.

[0062] Specifically, a Tb doping concentration of 28 at.% was grown by the Czochralski method. 3+ ions and Dy doping concentration of 4 at.% 3+ Ion-doped LiLuF4 crystal.

[0063] The crystal was cut into 2cm thick a-cut crystal samples, polished end-faces, mounted on a copper base with a central aperture, and placed in a laser resonator. The input mirror had a transmittance of 90% at 450nm and 0.2% at 544nm; the output mirror had a transmittance of 2.0% at 544nm. A 544nm continuous solid-state laser output was achieved using a 450nm semiconductor laser end-pumping technique.

[0064] A Q-switching element is placed in the laser resonant cavity. In this embodiment, a passive Q-switching chip (specifically Cr 4+ :YAG crystal, Co 2+ : one of MgAl2O4 crystal or graphene) or a 544nm acousto-optic Q-switched element to achieve 544nm Q-switched pulsed laser operation.

[0065] A nonlinear optical element for frequency-doubled 544nm laser light (in this embodiment, an LBO or β-BBO crystal cut at a phase-matching angle for the 544nm frequency-doubled wavelength) is inserted between the laser gain medium of the laser resonator and the output mirror. The input mirror has a transmittance of T ≥ 90% at a wavelength of 450nm and a transmittance of T ≤ 0.1% at both 544nm and 272nm. The output mirror has a transmittance of T = 0.1% at a wavelength of 544nm and a transmittance of T ≥ 80% at the frequency-doubled wavelength of 272nm. Using a 450nm semiconductor laser for pumping, a 272nm frequency-doubled laser output is achieved.

[0066] Example 2

[0067] In Example 2 of the present invention, the pump light source is a 450nm semiconductor laser, and the laser gain medium is Tb 3+ ions, Dy 3+ Ion co-doped LiYF4 crystal; 450nm semiconductor laser pumping Tb 3+ ions, Dy 3+ The ion-co-doped LiYF4 crystal achieves 587nm visible band and 293.5nm frequency-doubled laser output.

[0068] Specifically, a Tb doping concentration of 16 at.% was grown by the Czochralski method. 3+ ions and Dy doping concentration of 3at.% 3+ Ion-doubly doped LiYF4 crystal.

[0069] The crystal was cut into 2.5 cm thick a-cut crystal samples. After end-face polishing, the samples were mounted on a copper base with a central aperture and placed in a laser resonator. The input mirror had a transmittance of 90% at 450 nm and 0.2% at 587 nm. To prevent green light oscillation, the output mirror had a transmittance of 80% at 544 nm and 3.0% at 587 nm. A 587 nm continuous solid-state laser output was achieved using a 450 nm semiconductor laser end-pumping.

[0070] A Q-switching element is placed in the laser resonant cavity. In this embodiment, a passive Q-switching chip (specifically Cr 4+ :YAG crystal, Co 2+ : one of MgAl2O4 crystal or graphene) or a 587nm acousto-optic Q-switched element to achieve 587nm Q-switched pulsed laser operation.

[0071] A nonlinear optical element for frequency-doubled 587nm laser light (in this embodiment, an LBO or β-BBO crystal cut at a phase-matching angle for the 587nm frequency-doubled wavelength) is inserted between the laser gain medium of the laser resonator and the output mirror. The input mirror has a transmittance of T ≥ 90% at a wavelength of 450nm and a transmittance of T ≤ 0.1% at wavelengths of 587nm and 293.5nm. The output mirror has a transmittance of T = 80% at a wavelength of 544nm, a transmittance of T = 0.1% at a wavelength of 587nm, and a transmittance of T ≥ 80% at the frequency-doubled wavelength of 293.5nm. 293.5nm frequency-doubled laser output is achieved using a 450nm semiconductor laser pump.

[0072] Example 3

[0073] In Example 3 of the present invention, the pump light source is a 450nm semiconductor laser, and the laser gain medium is Dy 3+ Doped LiTbF4 crystal; 450nm semiconductor laser pumped Dy 3+ The doped LiTbF4 crystal achieves 544nm green band and 272nm frequency-doubled laser output.

[0074] Specifically, the Dy with a doping concentration of 4 at.% was grown by the Czochralski method. 3+ Doped LiTbF4 crystals.

[0075] The crystal was cut into 2cm thick a-cut crystal samples, polished end-faces, mounted on a copper base with a central aperture, and placed in a laser resonator. The input mirror had a transmittance of 90% at 450nm and 0.2% at 544nm; the output mirror had a transmittance of 1.5% at 544nm. A 544nm continuous solid-state laser output was achieved using a 450nm semiconductor laser end-pumping technique.

[0076] A Q-switching element is placed in the laser resonant cavity. In this embodiment, a passive Q-switching chip (specifically Cr 4+ :YAG crystal, Co 2+ : one of MgAl2O4 crystal or graphene) or 544nm acousto-optic Q-switched element to achieve 544nm Q-switched pulsed laser operation.

[0077] A nonlinear optical element for frequency-doubled 544nm laser light (in this embodiment, an LBO or β-BBO crystal cut at a phase-matching angle for the 544nm frequency-doubled wavelength) is inserted between the laser gain medium of the laser resonator and the output mirror. The input mirror has a transmittance of T ≥ 90% at a wavelength of 450nm and a transmittance of T ≤ 0.1% at both 544nm and 272nm. The output mirror has a transmittance of T = 0.1% at a wavelength of 544nm and a transmittance of T ≥ 80% at the frequency-doubled wavelength of 272nm. 272nm frequency-doubled laser output is achieved using a 450nm semiconductor laser pump.

[0078] Example 4

[0079] In Example 4 of the present invention, the pump light source is a 450nm semiconductor laser, and the laser gain medium is Tb 3+ ions, Dy 3+ Ion co-doped CaF2 laser ceramics; using 450nm semiconductor laser pumping Tb 3+ ions, Dy 3+ Ion-co-doped CaF2 laser ceramics achieve 541nm green band and 270.5nm frequency-doubled laser output.

[0080] Specifically, a Tb doping concentration of 12 at.% was prepared by hot isostatic pressing. 3+ ions and Dy doping concentration of 4 at.% 3+ Ion-doped CaF2 laser ceramics.

[0081] A 1.8 cm thick sample was cut from the ceramic, end-polished, mounted on a copper base with a central aperture, and placed in a laser resonator. The input mirror had a transmittance of 90% at 450 nm and 0.2% at 541 nm; the output mirror had a transmittance of 1.0% at 541 nm. A 541 nm continuous solid-state laser output was achieved using a 450 nm semiconductor laser end-pumping technique.

[0082] A Q-switching element is placed in the laser resonant cavity. In this embodiment, a passive Q-switching chip (specifically Cr 4+ :YAG crystal, Co 2+: one of MgAl2O4 crystal or graphene) or 541nm acousto-optic Q-switched element to achieve 541nm Q-switched pulsed laser operation.

[0083] A nonlinear optical element (LBO or β-BBO crystal cut at a phase-matching angle for the 541nm frequency-doubled wavelength laser in this embodiment) is inserted between the laser gain medium of the laser resonator and the output mirror. The input mirror has a transmittance of 90% or higher at 450nm and 0.1% or lower at both 541nm and 270.5nm. The output mirror has a transmittance of 0.1% at 541nm and 80% or higher at the frequency-doubled wavelength of 270.5nm. 270.5nm frequency-doubled laser output is achieved using a 450nm semiconductor laser pump.

[0084] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A laser gain medium, characterized in that: The laser gain medium contains Tb 3+ ions and Dy 3+ ion materials, and Tb 3+ ions as active ions, Dy 3+ ions as sensitizing ions; The laser gain medium is doped with Tb 3+ ions and Dy 3+ Ion co-doped materials; The laser gain medium is Tb 3+ ions and Dy 3+ Ion-doped crystals, glasses or transparent ceramics; The crystal is LiLuF4, LiYF4, KY3F 10 , BaY2F8, BaLu2F8, LaF3, CaF2, Y3Al5O 12 , one of YAl3(BO3)4, KGd(WO4)2 or YVO4; The glass is fluoride glass; The transparent ceramic is CaF2 or Y3Al5O 12 ; The laser gain medium is doped with Dy 3+ Tb ions 3+ Self-activating materials; The laser gain medium is doped with Dy 3+ Tb ions 3+ self-activated crystals or transparent ceramics; The self-activated crystal is LiTbF4, TbF3, KTb3F 10 、BaTb2F8、Tb3Al5O 12 , one of TbAl3(BO3)4, KTb(WO4)2 or TbVO4; The transparent ceramic is Tb3Al5O 12 .

2. The laser gain medium according to claim 1, wherein The Tb 3+ The doping concentration of ions is greater than or equal to 10 at.%, and the Dy 3+ The doping concentration of ions is less than or equal to 5 at.%.

3. A visible band solid laser, characterized in that: Comprising a pump light source, an input mirror, an output mirror and the laser gain medium according to any one of claims 1 to 2; The laser gain medium is arranged on the outgoing light path of the pump light source; The input mirror and the output mirror form a laser resonant cavity, and the laser gain medium is located in the laser resonant cavity; The pump light source is a semiconductor laser, which is used to emit laser light in the 440nm-460nm band; The laser gain medium is used for emitting visible solid laser in the 540nm band or the 590nm band under the excitation of the pump light source.

4. The solid-state laser according to claim 3, characterized in that The transmittance of the input mirror is T≥80% in the 450nm band and T≤0.5% in the 520-600nm band; The output mirror has a transmittance of 0.5%≤T≤10% in the 520-600nm band.

5. The solid-state laser according to claim 3, characterized in that The solid laser further includes a Q-switching element or a mode-locking element in the visible band, and the Q-switching element or the mode-locking element is arranged between the laser gain medium and the output mirror.

6. The solid-state laser according to claim 5, characterized in that The Q-switching element is an acousto-optic Q-switching element.

7. The solid-state laser according to claim 5, characterized in that The Q-switching element is Cr 4+ :YAG or Co 2+ :MgAl2O4 crystals.

8. The solid-state laser according to claim 5, characterized in that The Q-switching element or mode-locking element is graphene, MoS2, black phosphorus or Bi2Se3.

9. The solid-state laser according to claim 5, characterized in that The Q-switching element or the mode-locking element is a semiconductor saturable absorption mirror.

10. The solid-state laser according to claim 9, characterized in that The semiconductor saturable absorber mirror serves as the output mirror while serving as the Q-switching element or the mode-locking element.

11. The solid-state laser according to claim 5, characterized in that The laser comprises a nonlinear optical element in the visible band, wherein the cutting angle of the nonlinear optical element is the frequency-doubled phase matching angle of the fundamental laser wavelength emitted by the laser gain medium; the nonlinear optical element is arranged between the laser gain medium and the output mirror; The transmittance T of the input mirror is ≥80% in the 450nm band, and the transmittance T is ≤0.5% in the 520-600nm band and the double frequency band; the transmittance T of the output mirror is ≤0.5% in the 520-600nm band, and the transmittance T is ≥70% in the double frequency band.

12. The solid-state laser according to claim 11, characterized in that The nonlinear optical element is LBO or β-BBO crystal.

13. The solid-state laser according to claim 11, characterized in that The nonlinear optical element is arranged between the Q-switching element or the mode-locking element and the output mirror.

14. The solid-state laser according to claim 3, characterized in that The solid laser further comprises a wavelength tuning element in the visible band; the wavelength tuning element is arranged between the laser gain medium and the output mirror.

15. The solid-state laser according to claim 14, characterized in that The wavelength tuning element is a birefringent filter, a grating or a prism.

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