Q-SWITCH STRUCTURE AND METHOD OF PRODUCING Q-SWITCH STRUCTURE

Abstract

A Q-switch structure including, a solid-state laser medium, and a magneto-optical material, wherein the solid-state laser medium and the magneto-optical material are joined and integrated. In addition, the solid-state laser medium has a thickness of 1 mm or more, and the solid-state medium and the magneto-optical material are directly joined. Consequently, the Q-switch is applicable to high optical output and contributes to the miniaturization of a laser apparatus.

Claims

1-10. (canceled)

11. A Q-switch structure comprising: a solid-state laser medium; and a magneto-optical material, wherein the solid-state laser medium and the magneto-optical material are joined and integrated; the solid-state laser medium has a thickness of 1 mm or more; and the solid-state medium and the magneto-optical material are directly joined.

12. The Q-switch structure according to claim 11, wherein the magneto-optical material is formed by crystal growth on the solid-state laser medium by using the solid-state laser medium as a substrate thereby joining and integrating with the solid-state laser medium.

13. The Q-switch structure according to claim 11, wherein the magneto-optical material is a bismuth-substituted rare earth iron garnet.

14. The Q-switch structure according to claim 12, wherein the magneto-optical material is a bismuth-substituted rare earth iron garnet.

15. The Q-switch structure according to claim 11, wherein the solid-state laser medium is selected from any one of ceramics selected from the group comprised of Y.sub.3Al.sub.5O.sub.12, Gd.sub.3Ga.sub.5O.sub.12, and (GdCa).sub.3(GaMgZr).sub.5O.sub.12 doped with anyone selected from the group comprised of Nd, Yb, and Cr.

16. The Q-switch structure according to claim 12, wherein the solid-state laser medium is selected from any one of ceramics selected from the group comprised of Y.sub.3Al.sub.5O.sub.12, Gd.sub.3Ga.sub.5O.sub.12, and (GdCa).sub.3(GaMgZr).sub.5O.sub.12 doped with anyone selected from the group comprised of Nd, Yb, and Cr.

17. The Q-switch structure according to claim 13, wherein the solid-state laser medium is selected from any one of ceramics selected from the group comprised of Y.sub.3Al.sub.5O.sub.12, Gd.sub.3Ga.sub.5O.sub.12, and (GdCa).sub.3(GaMgZr).sub.5O.sub.12 doped with anyone selected from the group comprised of Nd, Yb, and Cr.

18. The Q-switch structure according to claim 14, wherein the solid-state laser medium is selected from any one of ceramics selected from the group comprised of Y.sub.3Al.sub.5O.sub.12, Gd.sub.3Ga.sub.5O.sub.12, and (GdCa).sub.3(GaMgZr).sub.5O.sub.12 doped with anyone selected from the group comprised of Nd, Yb, and Cr.

19. A Q-switch solid-state laser apparatus comprising: the Q-switch structure according to claim 11 and a magnetic flux generator being arranged between a pair of resonant mirrors.

20. A Q-switch solid-state laser apparatus comprising: the Q-switch structure according to claim 12 and a magnetic flux generator being arranged between a pair of resonant mirrors.

21. A method of producing a Q-switch structure comprising a solid-state laser medium and a magneto-optical material in which the solid-state laser medium and the magneto-optical material are joined and integrated, the method comprising the steps of: preparing the solid-state laser medium having a thickness of 1 mm or more; and forming the magneto-optical material by crystal growth on the solid-state laser medium by using the solid-state laser medium as a substrate; and thereby producing the Q-switch structure in which the solid-state laser medium and the magneto-optical material are directly joined and integrated.

22. The method of producing the Q-switch structure according to claim 21, wherein a method for the crystal growth is a liquid phase epitaxial growth method.

23. The method of producing the Q-switch structure according to claim 21, wherein the magneto-optical material is a bismuth-substituted rare earth iron garnet.

24. The method of producing the Q-switch structure according to claim 22, wherein the magneto-optical material is a bismuth-substituted rare earth iron garnet.

25. The method of producing the Q-switch structure according to claim 21, wherein the solid-state laser medium is selected from any one of ceramics selected from the group comprised of Y.sub.3Al.sub.5O.sub.12, Gd.sub.3Ga.sub.5O.sub.12, and (GdCa).sub.3(GaMgZr).sub.5O.sub.12 doped with anyone selected from a group comprised of Nd, Yb, and Cr.

26. The method of producing the Q-switch structure according to claim 22, wherein the solid-state laser medium is selected from any one of ceramics selected from the group comprised of Y.sub.3Al.sub.5O.sub.12, Gd.sub.3Ga.sub.5O.sub.12, and (GdCa).sub.3(GaMgZr).sub.5O.sub.12 doped with anyone selected from a group comprised of Nd, Yb, and Cr.

27. The method of producing the Q-switch structure according to claim 23, wherein the solid-state laser medium is selected from any one of ceramics selected from the group comprised of Y.sub.3Al.sub.5O.sub.12, Gd.sub.3Ga.sub.5O.sub.12, and (GdCa).sub.3(GaMgZr).sub.5O.sub.12 doped with anyone selected from a group comprised of Nd, Yb, and Cr.

28. The method of producing the Q-switch structure according to claim 24, wherein the solid-state laser medium is selected from any one of ceramics selected from the group comprised of Y.sub.3Al.sub.5O.sub.12, Gd.sub.3Ga.sub.5O.sub.12, and (GdCa).sub.3(GaMgZr).sub.5O.sub.12 doped with anyone selected from a group comprised of Nd, Yb, and Cr.

29. A method of producing a Q-switch solid-state laser apparatus comprising: producing the Q-switch structure by the method of producing a Q-switch structure according to claim 21; and producing the Q-switch solid-state laser apparatus by arranging the Q-switch structure and a magnetic flux generator between a pair of resonant mirrors.

30. A method of producing a Q-switch solid-state laser apparatus comprising: producing the Q-switch structure by the method of producing a Q-switch structure according to claim 22; and producing the Q-switch solid-state laser apparatus by arranging the Q-switch structure and a magnetic flux generator between a pair of resonant mirrors.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0044] FIG. 1 is a schematic diagram illustrating an example of a structure of a Q-switch structure schematically according to the present invention.

[0045] FIG. 2 is a cross-sectional view illustrating an example of a structure of a Q-switch structure schematically according to the present invention.

[0046] FIG. 3 is a cross-sectional view illustrating an example of a structure of a Q-switch solid-state laser apparatus having a Q-switch structure according to the present invention.

[0047] FIG. 4 is a flowchart illustrating an example of a method of producing a Q-switch structure according to the present invention.

DESCRIPTION OF EMBODIMENTS

[0048] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited thereto. An example of a structure of an inventive Q-switch structure is described with reference to FIG. 1 and FIG. 2. FIG. 1 illustrates a schematic diagram of a structure of a Q-switch structure. FIG. 2 illustrates a cross-sectional view of the structure.

[0049] An inventive Q-switch structure 10 includes a solid-state laser medium 11 and a magneto-optical material 12, and the solid-state laser medium 11 and the magneto-optical material 12 are joined and integrated. Furthermore, the solid-state laser medium 11 has a thickness of 1 mm or more, and the solid-state laser medium 11 and the magneto-optical material 12 are joined directly in the present invention.

[0050] More specifically, the magneto-optical material 12 is grown by crystal growth on the solid-state laser medium 11 by using the solid-state laser medium 11 as a substrate for crystal growth. The magneto-optical material 12 is preferably joined and integrated with the solid-state laser medium 11 by crystal growth.

[0051] Such a Q-switch structure 10 functions as a Q-switch by combining the magneto-optical material 12 and a magnetic flux generator. FIG. 3 illustrates an example of a structure of a Q-switch solid-state laser apparatus. A Q-switch solid-state laser apparatus 20 arranges the Q-switch structure 10 and a magnetic flux generator 23 between a pair of resonant mirrors (a first resonant mirror 21 and a second resonant mirror 22) as above described. FIG. 3 illustrates an example in which all these structures are joined and integrated. However, in the present invention, only the solid-state laser medium 11 and the magneto-optical material 12 configuring the Q-switch structure 10 need to be joined and integrated, and other materials for the structure can be arranged appropriately. For example, the magnetic flux generator can be a combination of a permanent magnet and an exciting coil, and the exciting coil can be arranged around the permanent magnet.

[0052] Materials usable for the solid-state laser mediums can be used for a material for the solid-state laser medium 11 in the inventive Q-switch structure 10. Specifically, considering crystal growth when the solid-state laser medium 11 is used as a substrate, the material is preferably selected from any one of ceramics selected from the group comprised of Y.sub.3Al.sub.5O.sub.12, Gd.sub.3Ga.sub.5O.sub.12, and (GdCa).sub.3(GaMgZr).sub.5O.sub.12 doped with anyone selected from a group comprised of Nd, Yb, and Cr. Additionally, materials usable for the magneto-optical materials can be used for material for the magneto-optical material 12 in the inventive Q-switch structure 10. Considering the crystal growth, the magneto-optical material 12 is preferably a bismuth-substituted rare earth iron garnet.

[Method of Producing Q-Switch Structure]

[0053] Then, an inventive method of producing a Q-switch structure is explained. An inventive method of producing a Q-switch structure is a method of producing a Q-switch structure 10 comprising a solid-state laser medium 11 and a magneto-optical material 12, as shown in FIG. 1 and FIG. 2, in which the solid-state laser medium 11 and the magneto-optical material 12 are joined and integrated, the method comprising the steps of: [0054] preparing the solid-state laser medium 11 having a thickness of 1 mm or more; and [0055] forming the magneto-optical material 12 by crystal growth on the solid-state laser medium 11 by using the solid-state laser medium as a substrate; and [0056] thereby producing the Q-switch structure 10 in which the solid-state laser medium 11 and the magneto-optical material 12 are directly joined and integrated.

[0057] The inventive method of producing the Q-switch structure is described in detail with reference to FIG. 4. Firstly, as illustrated in S1 in FIG. 4, the solid-state laser medium 11 having a thickness of more than 1 mm is prepared (Step S1). The solid-state laser medium 11 prepared here is used as a substrate for crystal growth, thus needs to have a thickness of more than 1 mm. Materials usable for the solid-state laser mediums can be used for a material for the solid-state laser medium 11. Among them, the material is preferably selected from any one of ceramics selected from the group comprised of Y.sub.3Al.sub.5O.sub.12, Gd.sub.3Ga.sub.5O.sub.12, and (GdCa).sub.3(GaMgZr).sub.5O.sub.12 doped with anyone selected from a group comprised of Nd, Yb, and Cr. These yttrium aluminum garnet (YAG), gadolinium gallium garnet (GGG), and CaMgZr substitution type gadolinium gallium garnet (SGGG) are not only excellent for the solid-state laser medium but also particularly preferred when the magneto-optical material 12 is bismuth-substituted rare earth iron garnet as described below.

[0058] Then, as illustrated in S2 of FIG. 4, using the solid-state laser medium 11 as a substrate, the magneto-optical material 12 is grown by crystal growth on the solid-state laser medium 11 (step 82). In this case, the crystal growth of the magneto-optical material 12 is preferably performed by the liquid phase epitaxial growth method (LPE). An ordinary method can be adopted as a method for liquid-phase epitaxial growth. For example, this can be done by heating and melting the material of the magneto-optical material 12 in a platinum crucible and then attaching the melt surface of the magneto-optical material 12 to one surface of the solid-state laser medium 11, which is the substrate.

[0059] For the material for the magneto-optical material 12, the materials usable in general for the magneto-optical material can be used. Among them, the magneto-optical material 12 is preferably a bismuth-substituted rare earth iron garnet. The bismuth-substituted rare earth iron garnet is excellent as the material for the magneto-optical material 12 configuring the Q-switch. When Yttrium aluminum garnet (YAG), gadolinium gallium garnet (GGG), and CaMgZr substitution type gadolinium gallium garnet (SGGG) are used as described above for the material for the solid-state laser medium 11, which is the substrate for the crystal growth, the bismuth-substituted rare earth iron garnet used for the magneto-optical material 12 makes the crystal growth easier because both of them are the garnets.

[0060] Using a Q-switch structure produced by the method of producing the Q-switch structure described above, the Q-switch solid-state laser apparatus can be produced by arranging the Q-switch structure and a magnetic flux between a pair of resonant mirrors.

Example

[0061] Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. However, the present invention is not limited thereto.

Example 1-1

[0062] As described below, a Q-switch structure 10, illustrated in FIG. 1 and FIG. 2, was produced.

[0063] Firstly, a solid-state laser medium 11 (Nd: SGGG) was prepared from CaMgZr substitution type gadolinium gallium garnet (SGGG) doped with Nd (Step S1 in FIG. 4). This solid-state laser medium 11 had a thickness of 1.5 mm and a diameter of 1 inch (25.4 mm) and was used as a substrate material. The solid-state laser medium 11 was used as the substrate for crystal growth.

[0064] Secondly, Tb.sub.4O.sub.7, Eu.sub.2O.sub.3, Fe.sub.2O.sub.3, Ga.sub.2O.sub.3, and Bi.sub.2O.sub.3 were introduced into a platinum crucible and melted by heating to a temperature of 1050? C. Then, the temperature of the heat-melted melt was lowered to 850? C. Moreover, the solid-state laser medium 11, which was a substrate for the crystal growth, was attached to a melt surface in the platinum crucible, and grown the 250 ?m crystal by an LPE method (Step S2 in FIG. 4). Consequently, the magneto-optical material 12 (bismuth-substituted rare earth iron garnet) was grown on the solid-state laser medium 11 by the crystal growth. Then the solid-state laser medium 11 and the magneto-optical material 12 were directly joined and integrated, hence the Q-switch structure 10 was produced.

[0065] A crystal surface of the magneto-optical material 12 and a surface of the solid-state laser medium 11, which was the substrate, were optically polished to adjust a Faraday rotation angle to 45 deg when infrared light of 1064 nm wavelength was irradiated.

[0066] To evaluate an optical characteristic of the Q-switch structure 10 (an integrated sample of the solid-state laser medium 11 and the magneto-optical material 12), both surfaces (polished surfaces) of the magneto-optical material 12 and the solid-state laser medium 11 were coated with an antireflection film coating for air, and then the evaluation of the optical characteristic was performed. As a result, an insertion loss of 1.1 dB and an extinction ratio of 29 dB was gained. The extinction ratio of less than 30 dB was due to the effect of an interface reflection caused by the refractive index difference between the solid-state laser medium 11 and the magneto-optical material 12. This is within the acceptable range for this material combination.

Example 1-2

[0067] A Q-switch structure 10 was produced as in Example 1-1, although a thickness was adjusted by polishing to set a Faraday rotation angle to 22.5 degrees. Then an optical characteristic was evaluated as in Example 1-1, an insertion loss of 0.65 dB and an extinction ratio of 29 dB was gained. Although the rotation angle was small, the insertion loss was reduced in the magneto-optical material 12 portions.

Example 1-3

[0068] In a Q-switch structure 10 that was produced as in Example 1-1, a Q-switch solid-state laser apparatus 20 was produced by forming a first resonant mirror 21 layer on a surface of a solid-state laser medium 11 and forming a second resonant mirror 22 layer on a surface of a magneto-optical material 12.

Example 2-1

[0069] A Q-switch structure 10 was produced as illustrated in FIG. 1 and FIG. 2 as described below.

[0070] Firstly, a solid-state laser medium 11 (Nd: GGG) was prepared from gadolinium gallium garnet (GGG) doped with Nd (Step S1 in FIG. 4). This solid-state laser medium 11 had a thickness of 1.5 mm and a diameter of 1 inch (25.4 mm) and was used as a substrate material. The solid-state laser medium 11 was used as the substrate for crystal growth.

[0071] Secondly, Tb.sub.4O.sub.7, Yb.sub.2O.sub.3, Fe.sub.2O.sub.3, Al.sub.2O.sub.3, and Bi.sub.2O.sub.3 were introduced into a platinum crucible and melted by heating to a temperature of 1100? C. Then, the temperature of the heat-melted melt was lowered to 850? C. Moreover, the solid-state laser medium 11, which was a substrate for the crystal growth, was attached to a melt surface in the platinum crucible, and grown the 300 ?m crystal by the LPE method (Step S2 in FIG. 4). Consequently, the magneto-optical material 12 (bismuth-substituted rare earth iron garnet) was grown on the solid-state laser medium 11 by the crystal growth. Then the solid-state laser medium 11 and the magneto-optical material 12 were directly joined and integrated, hence the Q-switch structure 10 was produced.

[0072] A crystal surface of the magneto-optical material 12 and a surface of the solid-state laser medium 11, which was the substrate, were optically polished to adjust a Faraday rotation angle to 22.5 deg when infrared light of 1064 nm wavelength was irradiated.

[0073] To evaluate an optical characteristic of the Q-switch structure 10 (an integrated sample of the solid-state laser medium 11 and the magneto-optical material 12), both surfaces (polished surfaces) of the magneto-optical material 12 and the solid-state laser medium 11 were coated with an antireflection film coating for air, and then the evaluation of the optical characteristic was performed. As a result, an insertion loss of 0.7 dB and an extinction ratio of 30 db was gained. The low extinction ratio of 30 dB was due to the effect of an interface reflection caused by the refractive index difference between the solid-state laser medium 11 and the magneto-optical material 12. This is within the acceptable range for this material combination.

Example 2-2

[0074] In a Q-switch structure 10 that was produced as in Example 2-1, a Q-switch solid-state laser apparatus 20 was produced by forming a first resonant mirror 21 layer on a surface of a solid-state laser medium 11 and forming a second resonant mirror 22 layer on a surface of a magneto-optical material 12.

Example 3-1

[0075] As described below, a Q-switch structure 10, which was illustrated in FIG. 1 and FIG. 2, was produced.

[0076] Firstly, a solid-state laser medium 11 (Nd: GGG) was prepared from gadolinium gallium garnet (GGG) doped with Nd (Step S1 in FIG. 4). This solid-state laser medium 11 had a thickness of 1.5 mm and a diameter of 1 inch (25.4 mm) and was used as a substrate material. This solid-state laser medium 11 was used as the substrate for crystal growth.

[0077] Secondly, Pr.sub.2O.sub.3, Lu.sub.2O.sub.3, Fe.sub.2O.sub.3, Ga.sub.2O.sub.3, and Bi.sub.2O.sub.3 were introduced into a platinum crucible and melted by heating to a temperature of 1100? C. Then, the temperature of the heat-melted melt was lowered to 850? C. Moreover, the solid-state laser medium 11, which was a substrate for the crystal growth, was attached to a melt surface in the platinum crucible and grown the 120 ?m crystal the by LPE method (Step 82 in FIG. 4). Consequently, the magneto-optical material 12 (bismuth-substituted rare earth iron garnet) was grown on the solid-state laser medium 11 by the crystal growth. Then the solid-state laser medium 11 and the magneto-optical material 12 were directly joined and integrated, hence the Q-switch structure 10 was produced.

[0078] A crystal surface of the magneto-optical material 12 and a surface of the solid-state laser medium 11, which was the substrate, were optically polished to adjust a Faraday rotation angle to 7.5 deg when infrared light of 1064 nm wavelength was irradiated.

[0079] To evaluate an optical characteristic of the Q-switch structure 10 (an integrated sample of the solid-state laser medium 11 and the magneto-optical material 12), both surfaces (polished surfaces) of the magneto-optical material 12 and the solid-state laser medium 11 were coated with an antireflection film coating for air, and then the evaluation of the optical characteristic was performed. As a result, an insertion loss of 0.6 db and an extinction ratio of 30 dB was gained.

Example 3-2

[0080] In a Q-switch structure 10 that was produced as in Example 3-1, a Q-switch solid-state laser apparatus 20 was produced by forming a first resonant mirror 21 layer on a surface of a solid-state laser medium 11 and forming a second resonant mirror 22 layer on a surface of a magneto-optical material 12.

[0081] In compositions used in Example 3-1 and Example 3-2, the magneto-optical material 12 indicated in-plane magnetic anisotropy and steep magnetic hysteresis, therefore low magnetic flux driving is enabled when Q-switch is produced.

[0082] It should be noted that the present invention is not limited to the above-described embodiments. The embodiments are just examples, and any examples that have substantially the same feature and demonstrate the same functions and effects as those in the technical concept disclosed in claims of the present invention are included in the technical scope of the present invention.