JP4640207B2 - Optical element manufacturing method - Google Patents

Description

The present invention relates to an optical element manufacturing method , and more particularly to an optical element manufacturing method capable of manufacturing an optical element that can improve manufacturing work efficiency and obtain stable characteristics.

An optical element having a structure in which a laser crystal and a wavelength conversion crystal are integrated and a manufacturing method thereof are known (see Patent Document 1).
On the other hand, a manufacturing method of a ferroelectric crystal having a periodic domain-inverted structure inside is known (see Patent Document 2).
JP 2005-57043 A JP-A-2005-208197

In an optical element having a structure in which a laser crystal and a wavelength conversion crystal are integrated, it is necessary to attach and integrate the laser light emission surface of the laser crystal and the laser light incident surface of the wavelength conversion crystal during manufacture. Here, if both the laser light emitting surface of the laser crystal and the laser light incident surface of the wavelength conversion crystal can have a large area, there is no difficulty in bonding.
However, the laser light incident surface of the wavelength conversion crystal may have a narrow area. For example, in a wavelength conversion crystal that needs to form a periodic domain-inverted structure in the crystal, the crystal thickness cannot be increased due to restrictions on the aspect ratio of the period of domain inversion of the periodic domain-inverted structure and the crystal thickness in the polarization direction. The laser light incident surface becomes a small area. In such a case, it is difficult to attach and integrate the laser light emitting surface of the laser crystal and the laser light incident surface of the wavelength conversion crystal, and there is a problem that the working efficiency is deteriorated. Further, it is difficult to bond with a stable quality, and there are problems that the characteristics differ depending on the location within the bonded surface, and the characteristics vary between optical elements.
SUMMARY OF THE INVENTION An object of the present invention is to provide an optical element manufacturing method capable of improving the manufacturing work efficiency and manufacturing an optical element capable of obtaining stable characteristics.

In a first aspect, the present invention provides a plurality of wavelength conversion crystal substrates (12) each having a plate-like body having an inverted polarization structure and a plurality of dummy material substrates (13) having a plate-like body. A step of alternately laminating on a surface (12a) other than the laser light incident surface (12i) of the substrate (12) to generate a first composite substrate (21), and the laser light of the first composite substrate (21) The surface having the incident surface (12i) and the surface having the laser light emitting surface (11o) of the laser crystal substrate (11), which is a plate-like body and one surface thereof is the laser light emitting surface (11o), are attached. Provided is a method for producing an optical element, comprising: a step of generating a second composite substrate (22); and a step of obtaining a plurality of optical elements (10) by cutting the second composite substrate (22). To do.
In the optical element manufacturing method according to the first aspect, the wavelength conversion crystal substrate (12 ) and the dummy material substrate (13 ) are bonded together, and then bonded to the laser crystal substrate ( 11). Can be taken. Since periodically poled polarization inversion period to the polarization direction of the crystal thickness aspect ratio limitations of structure is not the laser light entrance surface (1 2i) other surfaces (1 2a), the wavelength conversion crystal substrate ( 1 2) and can increase the bonding area of the dummy material substrate (1 3), the bonding work is easy. Further, attaching the first composite substrate (21) bonded to a wavelength conversion crystal substrate (1 2) and a dummy member substrate (1 3) to the laser crystal substrate (1 1), the wavelength conversion crystal substrate (1 2 ) and dummy material substrate (1 3) and order to become bonded area combined, the combined work becomes easy pasting Ri. Therefore, the work efficiency of manufacture can be improved. Furthermore, since it is possible to bond with stable quality, or different characteristics depending on the location in the bonding surface, there is no problem or variations in characteristics between the optical elements, the optical element with stable characteristics can be obtained.

In the method of manufacturing an optical element according to the first aspect, since the ferroelectric crystal having a periodic polarization inversion structure is used as the wavelength conversion crystal (2), the period of polarization inversion of the periodic polarization inversion structure and the polarization direction The crystal thickness aspect ratio is limited. Therefore, the present invention is particularly useful.

As the ferroelectric crystal, the use of lithium tantalate close to the stoichiometric composition (stoichiometric) or the stoichiometric composition, the formation of the periodically poled structure is facilitated.

As the lithium tantalate, the mole fraction _{Li 2 O / (Ta 2 O} 5 + Li 2 O) is a lithium tantalate less 0.500 or 0.490, formation of the periodically poled structure is facilitated .

When the lithium tantalate is doped with at least one of Mg, Zn, Sc, and In , the periodic domain-inverted structure can be easily formed.

In a second aspect, the present invention is that more pasted to the adhesive across the spacer having the same refractive index as the adhesive (5) the first composite substrate (21) to the laser crystal substrate (1 1) An optical element manufacturing method is provided.
If only the adhesive is used, the thickness of the adhesive is almost determined, and an etalon effect may occur.
Therefore, in the method for manufacturing an optical element according to the second aspect, by adjusting the optical path length across the spacer (5), Ru can be suppressed etalon effect.

In a third aspect, the present invention provides a method for manufacturing an optical element according to the first aspect, the first composite substrate (21) that paste by Opti cull contact (7) in the laser crystal substrate (1 1) An optical element manufacturing method is provided.
In the optical element manufacturing method according to the third aspect , since the optical contact (7) is used, the etalon effect does not occur.

In a fourth aspect, the present invention provides a method for manufacturing an optical element according to the first aspect, the wavelength conversion crystal substrate (1 2) and the dummy material substrate (1 3) and that that adhered by an adhesive An optical element manufacturing method is provided.
In the method for manufacturing an optical element according to the fourth aspect , since an adhesive is used, the operation becomes easier than when the optical contact (7) is used.

The method for manufacturing an optical element according to the first aspect, can be produced together multiple optical elements (10).

According to the manufacturing method of an optical element of the present invention, it is possible to improve the working efficiency of the production. Furthermore, an optical element having stable characteristics can be obtained.

  Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings. Note that the present invention is not limited thereby.

FIG. 1 is a perspective view illustrating an optical element 10 according to the first embodiment.
The optical element 10 includes a laser crystal 1 that emits a fundamental laser beam by being excited by excitation laser light Li from a semiconductor laser, and a wavelength conversion crystal 2 that emits a wavelength conversion laser beam Lo that is a harmonic of the fundamental laser beam. And a dummy material 3 sandwiching the wavelength conversion crystal 2 in a sandwich shape.

FIG. 2 is an exploded perspective view of the optical element 10.
The laser beam incident surface 2i of the plate-shaped wavelength conversion crystal 2 is attached to a part of the laser beam emitting surface 1o of the plate-shaped laser crystal 1. Further, one surface 3d of the plate-like dummy material 3 is attached to another part of the laser light emitting surface 1o of the laser crystal 1, and the other surface 3e of the dummy material 3 is incident on the laser light of the wavelength conversion crystal 2. Affixed to one surface 2a other than the surface 2i.

FIG. 3 is a flowchart showing the manufacturing procedure of the optical element 10.
In step S1, a wavelength conversion crystal large substrate 32 as shown in FIG. 4 is formed.
The wavelength conversion crystal large substrate 32 can be manufactured by the manufacturing method described in Patent Document 2, for example. That is, the periodic electrode 32b and the solid electrode 32c are formed on the opposing surfaces of the ferroelectric crystal large substrate 32a having a predetermined size, a voltage is applied between the electrodes, and the periodic polarization inversion structure is formed inside the ferroelectric crystal large substrate 32a. Form. The opposing direction of the electrodes is the polarization direction Dp, and the periodic pattern direction of the shape of the periodic electrode 32b is the polarization inversion direction Dr. The electrode may be left as it is or may be removed. When using an optical contact for bonding to the dummy material, it is preferable to remove it.

The ferroelectric crystal large substrate 32a is, for example, a MgO-doped, stoichiometric composition or stoichiometric lithium tantalate substrate (MgO doped stoichiometric lithium tantalate j substrate), The molar fraction Li ₂ O / (Ta ₂ O ₅ + Li ₂ O) is 0.49 or more and less than 0.5.

Returning to FIG. 3, in step S <b> 2, the wavelength conversion crystal large substrate 32 is cut with a dicing device so that the width of the polarization reversal direction Dr becomes a predetermined action length L, and a plurality of wavelength conversion crystal substrates 12 as shown in FIG. obtain. For example, the working length L of the wavelength conversion crystal substrate 12 is 2 mm, the thickness d is 0.4 mm, and the length G in the direction intersecting the polarization direction Dp and the polarization inversion direction Dr is 6 mm.
Then, the process proceeds to step S5.

In step S3, a dummy material large substrate having a thickness W and a dummy material large substrate having a thickness w are formed.
In step S4, the dummy material large substrate is cut into a size that matches the working length L and length G of the wavelength conversion crystal substrate 12 to obtain a plurality of dummy material substrates 13-1 and 13-2 as shown in FIG. For example, the thickness W of the dummy material substrate 13-1 is 1 mm, and the thickness w of the dummy material substrate 13-2 is 0.5 mm.
Then, the process proceeds to step S5.

  The dummy material is preferably made of a material having a thermal expansion coefficient comparable to that of the laser crystal 1 and the wavelength conversion crystal 2 in order to suppress adverse effects when thermally expanded. For example, a CLT substrate.

In step S5, as shown in FIG. 7, the wavelength conversion crystal substrate 12 and the dummy material substrate 13-1 are alternately bonded, and the dummy material substrate 13-2 is bonded to both ends, thereby forming the first composite substrate 21. . The width Z of the first composite substrate 21 in the bonded direction is, for example, 7 mm.
As the bonding method, an adhesive may be used, or an optical contact may be used.

In step S6, the two surfaces of the first composite substrate 21 facing the polarization reversal direction Dr are optically polished to form a necessary AR film or HR film. For example, an AR film for the fundamental wave is formed on one of the two surfaces, and an HR film is formed on the other.
Then, the process proceeds to step S10.

In step S7, a laser crystal large substrate having a predetermined thickness h is formed.
In step S8, the large laser crystal substrate is cut to a size matching the length G and width Z of the first composite substrate 21 to obtain the laser crystal substrate 11 as shown in FIG. For example, the thickness h of the laser crystal substrate 11 is 1 mm.
The laser crystal large substrate is, for example, a YAG crystal large substrate.

In step S9, the two surfaces of the laser crystal substrate 11 on which the laser beam is incident or emitted are optically polished to form a necessary AR film or HR film. For example, an AR film for the fundamental wave is formed on one of the two surfaces, and an HR film is formed on the other.
Then, the process proceeds to step S10.

In step S10, as shown in FIG. 8, the surface of the first composite substrate 21 on which the AR film is formed and the surface of the laser crystal substrate 11 on which the AR film is formed, that is, the laser light emitting surface 11a are bonded together. A substrate 22 is created.
As the bonding method, an adhesive may be used, or an optical contact may be used.

  In step S11, as shown in FIG. 9, the 2nd composite substrate 22 is cut | disconnected by the cutting line C, and the some optical element 10 is obtained.

  According to the optical element 10 according to the first embodiment, after the wavelength conversion crystal 2 and the dummy material 3 are bonded together, a manufacturing method in which the wavelength conversion crystal 2 and the dummy material 3 are bonded to the laser crystal 1 can be adopted. Since the area is the area where the wavelength conversion crystal 2 and the dummy material 3 are combined, the bonding operation is facilitated. Therefore, the work efficiency of manufacture can be improved. In addition, since it can be bonded with a stable quality, there is no problem that the characteristics are different depending on the location within the bonded surface or the characteristics vary between optical elements, and stable characteristics can be obtained. Furthermore, if a material having better thermal conductivity than the laser crystal 1 and the wavelength conversion crystal 2 is used as the dummy material 3, temperature control becomes easier than when the dummy material 3 is not provided.

  Moreover, according to the manufacturing method of the optical element which concerns on Example 1, the some optical element 10 can be manufactured collectively easily.

As shown in FIGS. 10 and 11, a spacer 5 may be sandwiched between the laser emission surface 1 o of the laser crystal 1, the laser light incident surface 2 i of the wavelength conversion crystal 2, and the surface 3 d of the dummy material 3. .
The spacer 5 is preferably made of a material that transmits fundamental laser light and has a thermal expansion coefficient comparable to that of the laser crystal 1.

  According to the optical element 10 according to the second embodiment, the etalon effect due to the adhesive can be reduced by making the thickness of the spacer 5 appropriate.

(1) As the wavelength conversion crystal large substrate 32, an LT substrate or LN substrate having a periodic polarization structure therein, an LT substrate or LN substrate doped with MgO, or a KTP substrate can also be used.
(2) As the dummy material large substrate, the same material as the wavelength conversion crystal 2 (periodic polarization inversion structure is not required), quartz glass, BK-7, or the like can be used.
(3) The dummy substrate 3 may be bonded to only one side of the wavelength conversion crystal 2.

  The optical element and the manufacturing method thereof according to the present invention can be used for, for example, a semiconductor excitation solid-state laser using SHG wavelength conversion technology.

1 is a perspective view showing an optical element according to Example 1. FIG. 1 is an exploded perspective view showing an optical element according to Example 1. FIG. FIG. 3 is a flowchart showing a manufacturing procedure of the optical element according to Example 1. It is a perspective view which shows a wavelength conversion crystal large substrate. It is a perspective view which shows a wavelength conversion crystal substrate. It is a perspective view which shows a dummy material board | substrate. It is a perspective view which shows a 1st composite substrate. It is a perspective view which shows the bonding process of a 1st composite substrate and a laser crystal substrate. It is a perspective view which shows a 2nd composite substrate. 6 is a perspective view showing an optical element according to Example 2. FIG. 6 is an exploded perspective view showing an optical element according to Embodiment 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser crystal 1o Laser beam emission surface 2 Wavelength conversion crystal 2i Laser beam incident surface 3 Dummy material 5 Spacer 10 Optical element 21 1st composite substrate 22 2nd composite substrate

Claims (4)

A plurality of wavelength conversion crystal substrates (12) each having a plate-like body and an inverted polarization structure and a plurality of dummy material substrates (13) of the plate-like body are connected to a laser light incident surface (12) of the wavelength conversion crystal substrate (12). A step of alternately laminating on a surface (12a) other than 12i) to generate a first composite substrate (21), and a surface and a plate having the laser light incident surface (12i) of the first composite substrate (21) The second composite substrate (22) is generated by pasting the surface of the laser crystal substrate (11) having the laser light emitting surface (11o) and the surface having the laser light emitting surface (11o). A method of manufacturing an optical element, comprising: a step; and a step of cutting the second composite substrate (22) to obtain a plurality of optical elements (10) . 2. The method of manufacturing an optical element according to claim 1, wherein the first composite substrate (21) is attached to the laser crystal substrate (11) with the adhesive having a spacer (5) having the same refractive index as that of the adhesive. A method for manufacturing an optical element . The method of manufacturing an optical element according to claim 1, wherein the first composite substrate (21) is attached to the laser crystal substrate (11) by optical contact . 2. The method of manufacturing an optical element according to claim 1, wherein the wavelength conversion crystal substrate (12) and the dummy material substrate (13) are attached with an adhesive .

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