JP2010147035A - Optical element and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element which has superior stability of laser oscillation even when having low excitation optical powder and low output, and to provide a method of manufacturing the optical element. <P>SOLUTION: A periphery of an optical path having reflecting mirrors (51, 52) at both ends and including a laser crystal (1) and a wavelength-converting crystal (2) is covered with dummy materials (3a, 3b, 3c, and 3d) to obtain an optical path as an optical waveguide. Because of the fact that the optical path serves as the optical waveguide, light can be laterally confined to obtain a stable lateral mode. Consequently, the laser oscillation becomes stable, with low excitation optical power and low output, even when sufficient thermal lens effect is not obtained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical element and a method for manufacturing the optical element, and more particularly to an optical element having excellent laser oscillation stability and a method for manufacturing the optical element.

An optical element having a structure in which a laser crystal and a wavelength conversion crystal are bonded together and a manufacturing method thereof are known (for example, see Patent Documents 1 and 2).
JP 2005-57043 A JP 2007-225786 A

In a conventional optical element, a laser crystal whose both ends are parallel plane polished and a wavelength conversion crystal whose both ends are parallel plane polished are bonded together to form a parallel plane type resonator. In such a parallel plane type resonator, the stability of laser oscillation is obtained by utilizing the thermal lens effect generated in the laser crystal. That is, due to the thermal lens effect, it operates in a pseudo manner as a semi-confocal resonator having higher stability than the parallel plane type, and the laser oscillation is stabilized.
However, when the pumping light power is high and the output is high, a sufficient thermal lens effect can be obtained, but when the pumping light power is low and the output is low, a sufficient thermal lens effect cannot be obtained and laser oscillation There is a problem that becomes unstable.
Accordingly, an object of the present invention is to provide an optical element having excellent laser oscillation stability even when the pumping light power is low and the output is low, and a method for manufacturing the optical element.

In the first aspect, the present invention provides a dummy material (3a, 3b, 3c,...) Around the optical path including the reflection mirrors (51, 52) at both ends and including the laser crystal (1) and the wavelength conversion crystal (2). Provided is an optical element (10) characterized in that the optical path is an optical waveguide covered with 3d).
In the optical element (10) according to the first aspect, since the optical path is an optical waveguide, light can be laterally confined and a stable lateral mode can be obtained. This stabilizes the laser oscillation even when the pumping light power is low, the output is low, and a sufficient thermal lens effect cannot be obtained.

In a second aspect, the present invention relates to a laser crystal large substrate (11) which is a plate-like body having an optical axis direction side (Z1), a width direction side (G1), and a thickness direction side (H1), and an optical axis. The wavelength conversion crystal large substrate (12), which is a plate-like body having a direction side (Z2), a width direction side (G1), and a thickness direction side (H1), is converted into a width direction side (G1) and a thickness direction side (H1). ) Are integrated by being sandwiched between the first dummy large substrate (31) and the second dummy large substrate (32) in a state where the surfaces partitioned by each other are in contact with each other. ) Are cut and separated perpendicularly to the plane partitioned by (4) to form a plurality of composite substrates (43), and the plurality of composites are formed by facing the planes partitioned by the optical axis direction side (Z1 + Z2) and the width direction side (G3). The substrates (43) are arranged side by side and integrated between the third dummy large substrate (33) and the fourth dummy large substrate (34). After forming HR coat (51, 52) on both end faces of the optical axis direction side (Z1 + Z2) of the composite large substrate (44) as a large substrate (44), the composite substrates (43) are separated from each other. There is provided a method for manufacturing an optical element, characterized in that a plurality of optical elements (10) are obtained by cutting a composite large substrate (44).
In the optical element manufacturing method according to the second aspect, the optical element (10) according to the first aspect can be mass-produced efficiently.

According to the optical element of the present invention, laser oscillation can be stabilized regardless of the excited state or output.
According to the method for manufacturing an optical element of the present invention, an optical element having excellent laser oscillation stability can be mass-produced efficiently.

  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. FIG. 2 is an exploded perspective view of the optical element 10.
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. Dummy materials 3a, 3b, 3c, 3d covering the periphery of the optical path formed from the laser crystal 1 and the wavelength conversion crystal 2 and using the optical path as an optical waveguide, and HR coats 51, 52 formed on both end faces of the optical path It is equipped with.

The laser crystal 1 is, for example, a YVO4 crystal or YAG crystal doped with Nd.
The wavelength conversion crystal 2 is, for example, a quasi phase matching type wavelength conversion crystal (for example, an SLT substrate doped with MgO) having a periodically poled structure.
The dummy materials 3a, 3b, 3c, and 3d are preferably made of a material having a thermal conductivity larger than that of glass so as to function suitably as a heat sink. Further, in order to suppress adverse effects when thermally expanded, it is preferable to use a material having a thermal expansion coefficient comparable to that of the laser crystal 1 and the wavelength conversion crystal 2. For example, it is the same material as the LT substrate and the wavelength conversion crystal 2 (no periodic polarization inversion structure is required).
The HR coats 51 and 52 are highly reflective to the fundamental laser beam (for example, wavelength 1.064 μm).

FIG. 3 is a flowchart showing the manufacturing procedure of the optical element 10.
In step S1, as shown in FIG. 4, a laser crystal large substrate 11 which is a plate-like body having an optical axis direction side length Z1, a width direction side length G1, and a thickness direction side length H1 is formed. For example, Z1≈1 mm, G1≈2 mm, and H1≈200 μm. Each surface of the laser crystal large substrate 11 is polished in parallel plane. Then, the process proceeds to step S4.

  On the other hand, in step S2, as shown in FIG. 5, the optical axis direction side length Z2 in the polarization inversion direction Dr2, the width direction side length G1 intersecting the polarization inversion direction Dr and the polarization direction Dp, and the thickness direction length in the polarization direction Dp. A wavelength conversion crystal large substrate 21 which is a plate of H1 is formed. For example, Z2≈2 mm, G1≈2 mm, and H1≈200 μm. Each surface of the wavelength conversion crystal large substrate 21 is polished in parallel plane. Then, the process proceeds to step S4.

  The wavelength conversion crystal large substrate 21 is formed, for example, by forming a periodic electrode 21b and a solid electrode 21c on the opposing surface of a ferroelectric crystal large substrate 21a of a predetermined size, and applying a voltage between the electrodes to form the ferroelectric crystal large substrate 21a. It can be created by forming a periodically poled structure inside. 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.

  On the other hand, in step S3, as shown in FIG. 6, the first dummy material large substrate 31 and the second substrate which are plate-like bodies having the length direction side length Z1 + Z2, the width direction side length G1, and the thickness direction side length H2. A dummy material large substrate 32, a third dummy material large substrate 33 and a fourth dummy material large substrate 34, which are plate-shaped bodies having a lengthwise side length Z1 + Z2, a widthwise side length G2, and a thickness direction side length H2. create. For example, Z1 + Z2≈3 mm, G1≈2 mm, and H2≈1 mm. G2≈8 mm. Each surface of each of the dummy large substrates 31 to 34 is polished in parallel plane. Then, the process proceeds to step S4.

  In step S4, as shown in FIG. 7, the laser crystal large substrate 11 and the wavelength conversion crystal large substrate 21 are in a state where the surfaces partitioned by the width direction side (G1) and the thickness direction side (H1) are in contact with each other. After being placed on the first dummy material large substrate 31 and pasted with an adhesive, the laser crystal large substrate 11 and the wavelength conversion crystal large substrate 21 are polished to a thickness direction length H3. For example, H3≈10 μm to 100 μm. Further, as shown in FIG. 8, the second dummy material large substrate 32 is placed so as to sandwich the laser crystal large substrate 11 and the wavelength conversion crystal large substrate 21, and after being attached with an adhesive, the side in the optical axis direction (Z1 + Z2) And a plurality of composite substrates 43 as shown in FIG. 9 are obtained by cutting along the cutting line C1 perpendicularly to the plane defined by the width direction side (G1). The composite substrate 43 has a side length G4 in the width direction. For example, G4≈200 μm.

  In step S5, as shown in FIG. 10, a plurality of composite substrates 43 are arranged on the polishing glass plate K with the surfaces partitioned by the optical axis direction side (Z1 + Z2) and the width direction side (G3) facing each other. Temporarily fixing with a temporary fixing agent (for example, wax), and surface polishing is performed to obtain a side length G3 of the composite substrate 43 in the width direction. For example, G3≈10 μm to 100 μm.

  In step S6, the third dummy large substrate 33 is attached to the flat-polished composite substrate 43 with an adhesive, and then the temporarily fixed polishing glass plate K is removed, and a plurality of composite substrates as shown in FIG. 33 is set in a state of being arranged and pasted on the third dummy material large substrate 33. Then, as shown in FIG. 12, a fourth dummy material large substrate 34 is attached so as to sandwich the composite substrate 43 to obtain a composite large substrate 44.

  In step S7, as shown in FIG. 12, HR coats 51 and 52 are formed on both end faces of the optical axis direction side (Z1 + Z2) of the composite large substrate 44. And the composite large board | substrate 44 is cut | disconnected by the cutting line C2 so that each composite board | substrate 43 may be isolate | separated, and the some optical element 10 is obtained.

  According to the first embodiment, since the optical path formed from the laser crystal 1 and the wavelength conversion crystal 2 is an optical waveguide, the light can be laterally confined and a stable lateral mode can be obtained. Even when a sufficient thermal lens effect cannot be obtained at the output, the laser oscillation becomes stable.

  In addition to the laser crystal 1 and the wavelength conversion crystal 2, another crystal (for example, non-doped YVO4) or the like may be inserted in the optical path.

  The optical element and the optical element manufacturing method of the present invention can be used for, for example, a semiconductor-excited 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 laser crystal large board | substrate. It is a perspective view which shows a wavelength conversion crystal large substrate. It is a perspective view which shows a dummy material large board | substrate. It is the perspective view which integrated the laser crystal large substrate, the wavelength conversion crystal large substrate, and the 1st dummy material large substrate. It is the perspective view which pinched | interposed the laser crystal large substrate and the wavelength conversion crystal large substrate with the 1st, 2nd dummy material large substrate. It is a perspective view which shows a composite substrate. It is a perspective view which shows the process of grind | polishing a some composite substrate. It is the perspective view which integrated the some composite substrate and the 3rd dummy material large board | substrate. It is the perspective view which pinched | interposed the some composite board | substrate with the 3rd, 4th dummy material large board | substrate. It is a perspective view showing formation and cutting separation of HR coat.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser crystal 2 Wavelength conversion crystal 3a-3d Dummy material 10 Optical element 11 Laser crystal large substrate 21 Wavelength conversion crystal large substrate 31-34 Dummy material large substrate 43 Composite substrate 44 Composite large substrate C1, C2 Cutting line

Claims (2)

An optical waveguide having reflection mirrors (51, 52) at both ends and covering the periphery of the optical path including the laser crystal (1) and the wavelength conversion crystal (2) with a dummy material (3a, 3b, 3c, 3d) An optical element (10) characterized in that The laser crystal large substrate (11) which is a plate-like body having the optical axis direction side (Z1), the width direction side (G1), and the thickness direction side (H1), and the optical axis direction side (Z2) and the width direction side ( G1) and the wavelength conversion crystal large substrate (12), which is a plate-like body having a thickness direction side (H1), are brought into contact with each other by dividing the width direction side (G1) and the thickness direction side (H1). In this state, the first dummy large substrate (31) and the second dummy large substrate (32) are sandwiched and integrated, and cut perpendicularly to the plane defined by the optical axis direction side (Z1 + Z2) and the width direction side (G1). A plurality of composite substrates (43) are separated, and a plurality of the composite substrates (43) are arranged with the surfaces defined by the sides in the optical axis direction (Z1 + Z2) and the width direction sides (G3) facing each other. A composite large substrate (44) is formed by sandwiching the substrate (33) and the fourth dummy large substrate (34), After forming the HR coat (51, 52) on both end surfaces of the side (Z1 + Z2) in the optical axis direction of the combined substrate (44), the combined large substrate (44) is cut so as to separate each combined substrate (43). And obtaining a plurality of optical elements (10).

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