JP2009047794A - Manufacturing method of wavelength conversion element, wavelength conversion element, light source device, illumination device, projector and monitor apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a wavelength conversion element high in light conversion efficiency, and to provide the wavelength conversion element, a light source device, an illumination device, a projector and a monitor apparatus. <P>SOLUTION: The manufacturing method of the wavelength conversion element having a domain inversion periodical structure, in which a domain inversion region 16b and a domain non-inversion region 16a are alternately arranged, comprises: a process of forming an insulation layer 11 having opening parts 11e with a prescribed interval on a part of a region to get to the domain inversion region 16b on one surface of a nonlinear optical member 10; a process of forming a first electrode 12 on the insulation layer 11 including an inner part of an opening part 11e and forming a second electrode 13 on the other surface 10b opposite to the one surface 10a of the nonlinear optical member 10; and a process of applying a voltage for domain-inverting the nonlinear optical member 10 between the first electrode 12 and the second electrode 13. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a wavelength conversion element, a wavelength conversion element, a light source device, an illumination device, a projector, and a monitor device.

In recent years, coherent light sources have become indispensable in measurement fields such as image display devices, optical communication fields, medical fields, and microscopes. Various wavelengths of coherent light are used depending on the purpose.
Therefore, wavelength conversion elements that use nonlinear optical effects are used in many fields because the wavelength used by laser light sources can be expanded by efficiently converting the wavelength of light by means of a domain-inverted structure having a periodic pitch. ing.
As a method of manufacturing such a wavelength conversion element, in order to determine the pitch of the domain-inverted region when performing domain inversion, electrodes are formed on the upper and lower surfaces of the substrate, and a high voltage is applied to the electrode to form a domain-inverted structure. A forming method has been proposed (see, for example, Patent Document 1 and Patent Document 2).

  In the domain control method for the nonlinear ferroelectric optical material described in Patent Document 1, a mask in which a metal film made of Ta (tantalum), for example, is deposited on the + C plane of the LiTaO 3 substrate. Then, a resist is coated on the mask, exposed from the + C plane side and developed, and a Ti film is formed on the resist by vapor deposition. Thereafter, the Ti film on the resist and the resist are removed, and the mask is etched to form an electrode of the Ti film in a region where the polarization is reversed. Further, a Ti film is deposited on the entire -C surface to form an electrode. Then, by applying an electric field of 200 kV / cm between the electrode on the + C plane and the electrode on the −C plane, a domain-inverted region is formed on the LiTaO 3 substrate.

In the ferroelectric polarization inversion method described in Patent Document 2, a periodic electrode is formed in a region where the polarization is inverted by vapor deposition or sputtering of Cr on the -Z plane of the MgO-LN substrate. This periodic electrode is formed such that a bent shape that repeats in a wave shape repeats at a constant period in order to regularly give charge concentration. Further, a corona wire is provided at a position toward the + Z plane, and the corona wire is connected to a high-voltage power supply via a connection line. Thereby, an electric field is applied to the MgO-LN substrate by corona charging, and a domain-inverted region is formed.
Japanese Patent Laid-Open No. 4-19719 JP 2003-5236 A

However, in the technique described in Patent Document 1, since a striped electrode is formed on the entire surface of the region where polarization is reversed, charge distribution occurs in the region where polarization is reversed, and a uniform domain-inverted periodic structure is obtained. It is difficult. That is, in the non-uniform domain-inverted periodic structure, the light conversion efficiency is lowered.
In the technique described in Patent Document 2, since the polarization inversion start position is a wave shape reflecting the wave shape of the electrode, the phase of the second harmonic depends on the light passing position on the incident end face of the MgO-LN substrate. Matching loss will occur.

  The present invention has been made to solve the above problems, and provides a method for manufacturing a wavelength conversion element, a wavelength conversion element, a light source device, an illumination device, a projector, and a monitor device with high light conversion efficiency. With the goal.

In order to achieve the above object, the present invention provides the following means.
A method for manufacturing a wavelength conversion element according to the present invention is a method for manufacturing a wavelength conversion element having a polarization inversion periodic structure in which polarization inversion regions and non-polarization inversion regions are alternately arranged, and includes one surface of a nonlinear optical member. A step of forming an insulating layer having openings at predetermined intervals in a part of a region to be the domain-inverted region, and a first electrode is provided on the insulating layer including the inside of the opening, and the nonlinear optical member Providing a second electrode on the other surface opposite to the one surface, and applying a voltage that reverses the polarization of the nonlinear optical member between the first electrode and the second electrode. It is characterized by.

In the method for manufacturing a wavelength conversion element according to the present invention, an insulating layer having openings at predetermined intervals is formed in a part of a region to be a polarization inversion region on one surface of a nonlinear optical member. Thereafter, the first electrode is formed on the insulation including the inside of the opening on one surface of the nonlinear optical member, the second electrode is formed on the other surface opposite to the one surface of the nonlinear optical member, and the first electrode A voltage is applied between the first electrode and the second electrode. Thereby, a polarization inversion periodic structure is formed in the nonlinear optical member.
At this time, since the openings are formed in the insulating layer at a predetermined interval in a part of the polarization inversion region of the nonlinear optical member, the first is compared with the case where the electrodes are formed on the entire surface in the polarization inversion region as in the prior art. The contact area between the electrode and the nonlinear optical member is reduced. In addition, the boundary between the first electrode and the insulating layer increases. As a result, the electric charge concentrates on the portion where the first electrode and the nonlinear optical member are in contact, and the domain-inverted region advances from the first electrode side to the second electrode side from the boundary portion. And the polarization inversion area | region which generate | occur | produced from the adjacent boundary part is connected. As described above, since the charge density is increased in the domain-inverted region, a voltage can be stably applied to the domain-inverted region of the nonlinear optical member. Therefore, for example, it is possible to obtain a uniform domain inversion periodic structure in which the duty ratio of the wavelength conversion element (the ratio of the domain inversion to the domain inversion period) is 50%.
Moreover, since the method of forming openings in the insulating layer at predetermined intervals can be formed by photolithography, the wavelength conversion element can be manufactured by a simple manufacturing method.

  In the wavelength conversion element manufacturing method of the present invention, it is preferable that a plurality of the openings are formed in one polarization inversion region in a direction intersecting with the polarization inversion period direction of the nonlinear optical member.

  In the wavelength conversion element manufacturing method according to the present invention, a plurality of openings are formed in one polarization inversion region in a direction intersecting with the polarization inversion period direction of the nonlinear optical member. Thereby, in the polarization inversion region, the contact area between the nonlinear optical member and the first electrode is smaller than in the case where a plurality of openings are not provided. That is, the boundary portion where the electric field density between the first electrode and the insulating layer is high increases in the direction of the domain inversion period and the direction intersecting with the domain inversion period direction. Therefore, a more uniform domain-inverted periodic structure can be formed inside the domain-inverted region of the nonlinear optical member.

  In the wavelength conversion element manufacturing method of the present invention, the interval between the first electrodes formed in the adjacent openings in the direction crossing the polarization inversion period direction is the same as the polarization inversion period direction of the first electrode. It is preferably smaller than the width and smaller than half the pitch of the first electrode.

  In the wavelength conversion element manufacturing method according to the present invention, the interval between the adjacent first electrodes is smaller than the dimension of the first electrode in the polarization inversion direction in the direction intersecting the polarization inversion period direction, and the pitch of the first electrodes Is less than half the dimension. Thereby, since the polarization inversion area | region which generate | occur | produced from the adjacent 1st electrode becomes easy to connect, it becomes possible to obtain a polarization inversion area | region reliably.

  In the wavelength conversion element manufacturing method according to the present invention, the first electrode formed in the opening arranged in a direction intersecting the polarization inversion period direction may have the opening in each row in the polarization inversion period direction. It is preferable that they are shifted in the arrangement direction.

  In the method for manufacturing a wavelength conversion element according to the present invention, when the domain-inverted regions generated from the first electrodes arranged in the direction intersecting the domain-inverted periodic direction are connected, the domain-inverted direction in the direction intersecting the domain-inverted periodic direction This is effective when the region does not become a straight line. That is, the first electrodes formed in the adjacent openings are shifted in the arrangement direction of the openings for each row in the polarization inversion period direction. As a result, the width of the polarization inversion period direction of the non-polarization inversion region is constant in the direction intersecting with the polarization inversion period direction, and the width of the polarization inversion period direction of the polarization inversion region is not constant in the direction intersecting with the polarization inversion period direction. Absent. Thereby, by adjusting the incident position of the light incident on the wavelength conversion element, it becomes easier to make the light incident on the region satisfying the phase matching relatively efficiently. Details will be described later with reference to the drawings.

  In the method of manufacturing a wavelength conversion element of the present invention, in the step of forming the opening, the non-polarization inversion is performed in the step of forming in the polarization reversal period direction of the nonlinear optical member and in the step of forming the insulating layer. A first insulating layer is formed in the region, and a second insulating layer is formed in the domain-inverted region at a predetermined interval. A dimension of the first insulating layer in a domain-inverted period direction It is preferably larger than the dimension in the domain inversion period direction and larger than half the pitch of the domain inversion period.

  Further, in the method for manufacturing a wavelength conversion element according to the present invention, since the contact area between the first electrode and the nonlinear optical member is smaller than in the prior art, the electric charge is concentrated on the first electrode in contact with the nonlinear optical member. The domain-inverted region extends in the domain-inverted period direction. At this time, the width of the first insulating layer in the direction of polarization inversion period is larger than the width of the second insulating layer in the direction of polarization inversion period, and larger than half the pitch of the polarization inversion period. Therefore, even when the domain-inverted region extends in the domain-inverted periodic direction, it is possible to efficiently obtain a uniform domain-inverted periodic structure with a duty ratio of, for example, 50%.

  The wavelength conversion element manufacturing method of the present invention is a method for manufacturing a wavelength conversion element having a polarization inversion periodic structure in which polarization inversion regions and non-polarization inversion regions are alternately arranged. Forming an insulating layer having a thickness smaller than the thickness of the non-polarization inversion region in a region serving as the polarization inversion region in the direction of polarization inversion period of the surface, and forming a first electrode on the insulating layer, Forming a second electrode on the other surface opposite to the one surface of the nonlinear optical member, and applying a voltage that reverses the polarization of the nonlinear optical member between the first electrode and the second electrode And a process.

In the method for manufacturing a wavelength conversion element according to the present invention, the insulating layer is formed on one surface of the nonlinear optical member so that the thickness of the region serving as the polarization inversion region is smaller than the thickness of the non-polarization inversion region. Thereafter, a first electrode is formed on one surface of the nonlinear optical member, a second electrode is formed on the other surface opposite to the one surface of the nonlinear optical member, and a voltage is applied between the first electrode and the second electrode. Apply. Thereby, a polarization inversion period is formed in the nonlinear optical member.
At this time, for example, by forming a cross-sectional view type insulating layer so that the nonlinear optical member and the first electrode are in line contact with each other, compared with the conventional case where the electrode is formed on the entire surface in the domain-inverted region. Thus, the portions of the first electrode and the nonlinear optical member are reduced. Thereby, electric charges concentrate on the part where the first electrode and the nonlinear optical member are in contact with each other. Thus, since the charge density increases in the domain-inverted region, a voltage can be stably applied to the domain-inverted region of the nonlinear optical member. Further, since the nonlinear optical member and the first electrode are in line contact, it is possible to improve the electric field contrast between the domain-inverted region and the non-domain-inverted region. Therefore, it is possible to obtain a uniform polarization inversion periodic structure in which the duty ratio of the wavelength conversion element (the ratio of the domain inversion to the domain inversion period) is, for example, 50%.
Moreover, since the method of changing the film thickness of the insulating layer can be formed by a photolithography method, the wavelength conversion element can be manufactured by a simple manufacturing method.

  In the wavelength conversion element manufacturing method of the present invention, it is preferable that a resin material is used as a material of the insulating layer, and the step of forming the insulating layer includes a reflow step of heating and melting the insulating layer.

In the method for manufacturing a wavelength conversion element according to the present invention, a resin material is used as the material of the insulating layer, and a reflow treatment step is provided, so that the insulating layer has an opening or a portion having a small thickness with respect to one surface of the nonlinear member. Inclined gently toward Thus, by forming the first insulating layer and the second insulating layer so as to have a curved surface above the nonlinear optical member, the first insulating layer and the second insulating layer are not affected when the first electrode is formed. do not become. This makes it easier to form the first electrode uniformly in the opening of the insulating layer and the recessed region of the insulating layer having a film thickness distribution, so that the film thickness becomes relatively uniform without disconnection or the like. Therefore, since a voltage can be reliably applied between the first electrode and the second electrode, the domain-inverted region can be formed with high accuracy.
In addition, when the insulating layer includes the first insulating layer and the second insulating layer, the size of the opening between the first insulating layer and the second insulating layer can be adjusted depending on the reflow processing conditions. The contact area between the first electrode and one surface of the non-linear optical member can be adjusted. Therefore, since the charge density of the domain-inverted region of the nonlinear optical member can be adjusted according to the material of the nonlinear member, a highly accurate domain-inverted periodic structure can be obtained.
In addition, since the first insulating layer and the second insulating layer can be brought into contact with each other on the nonlinear optical member by the reflow processing step, the boundary between the first insulating layer and the first electrode, and the second insulating layer And the boundary between the first electrode and the first electrode. Thereby, the contrast of the electric field between the domain-inverted region and the non-domain-inverted region can be improved.

The wavelength conversion element of the present invention is manufactured by the above-described method for manufacturing a wavelength conversion element.
In the wavelength conversion element according to the present invention, it is possible to form a uniform polarization inversion period in the direction in which the light of the nonlinear optical member is incident by the above-described method for manufacturing a wavelength conversion element. Therefore, it is possible to provide a wavelength conversion element with high light conversion efficiency.

  In addition, a light source device of the present invention includes a light source that emits light and the wavelength conversion element that converts a wavelength of light emitted from the light source into a predetermined wavelength.

  In the light source device according to the present invention, part of the light emitted from the light source is converted into a predetermined wavelength by the wavelength conversion element. Here, since the wavelength conversion element has high light conversion efficiency, it is possible to improve the light use efficiency of the entire apparatus.

Moreover, the illuminating device of this invention is equipped with the said light source device, It is characterized by the above-mentioned.
Since the illumination device according to the present invention includes a light source device with high light utilization efficiency, bright light can be emitted.

  A projector according to the present invention includes the light source device described above, a light modulation unit that modulates light emitted from the light source device, and a projection device that projects light modulated by the light modulation unit. .

  In the projector according to the present invention, the light emitted from the light source device is modulated by the light modulation means. The modulated light is projected by the projection device. Here, since the projector includes a light source device with high light use efficiency, it is possible to project a bright and clear image.

  A monitor device according to the present invention includes the light source device described above and an imaging unit that captures an image of a subject using light emitted from the light source device.

  In the monitor device according to the present invention, the light emitted from the light source device irradiates the subject, and the subject is imaged by the imaging means. At this time, as described above, since the light source device with high light utilization efficiency is provided, the subject is irradiated with bright light. Therefore, the subject can be clearly imaged by the imaging means.

Hereinafter, embodiments of a wavelength conversion element manufacturing method, a wavelength conversion element, a light source device, an illumination device, a projector, and a monitor device according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.
FIG. 1 is a perspective view showing a polarization inversion periodic structure of the wavelength conversion element of the present embodiment, FIG. 2 is a cross-sectional view of a main part showing a state where an insulating layer is formed on a nonlinear optical member, and FIG. FIGS. 4A and 4B are perspective views showing a state in which the insulating layer is formed into a predetermined shape by a photolithography method, and FIGS. 4A and 4B are main part cross-sectional views showing the state after the reflow treatment. FIG. 6 is a cross-sectional view of a main part showing a state in which an electrode is deposited, FIG. 6 is a cross-sectional view of a main part showing a state in which a voltage is applied to the electrode, and FIGS. 7 (a) and 7 (b) are nonlinear optical members. FIG. 8 is a main part sectional view showing the progress of the polarization inversion region, and FIG. 9 is a main part sectional view showing the domain inversion periodic structure.

[First Embodiment]
As shown in FIG. 1, the wavelength conversion element 1 manufactured by the wavelength conversion element manufacturing method according to the present invention has a domain repetitive structure in which non-polarization inversion regions 16a and polarization inversion regions 16b are alternately formed. . The direction (polarization inversion periodic direction) in which the non-polarization inversion regions 16a and the polarization inversion regions 16b of the wavelength conversion element 1 are alternately formed is defined as the X direction, and light is incident in the X direction. The width of the non-polarization inversion region 16a in the X direction of the wavelength conversion element 1 is P1, and the width of the polarization inversion region 16b is P2. The width P1 and the width P2 are substantially the same, and the pitch of the polarization inversion period is Λ (Λ = P1 + P2). Further, the non-polarization inversion region 16a indicates a region having the original spontaneous polarization direction of the nonlinear optical member, and the polarization inversion region 16b indicates a region in which the original spontaneous polarization direction is inverted.
The Y direction is the longitudinal direction of the domain-inverted region 16b, and the Z direction is the direction in which a voltage is applied to the nonlinear optical member.
The pitch Λ of the polarization inversion period is determined by the wavelength to be converted. In order to emit blue light, the pitch P of the polarization inversion period is 4.3 μm, and in order to emit green light. The pitch P of the polarization inversion period is 6.8 μm. In order to emit red light, the pitch P of the polarization inversion period is 10.2 μm. This value is only an example.

Next, a method for manufacturing the wavelength conversion element 1 according to the present invention will be described with reference to FIGS.
First, as shown in FIG. 2, a LiNbO 3 (lithium niobate) substrate (nonlinear optical member) 10 is prepared in a vacuum chamber (not shown), and the vacuum chamber is evacuated by a vacuum pump. After the vacuum chamber is evacuated, a resist (insulating layer) 11 is applied to the entire upper surface (one surface) 10 a of the LiNbO 3 substrate 10. In this embodiment, a resist is used as an example of a resin material.
Then, by using a photolithography method, as shown in FIG. 3, openings 11e are formed at a predetermined interval in the resist 11 corresponding to a region that will later become the domain-inverted region 16b. Here, for convenience of explanation, the resist layer 11 is referred to as a first resist (first insulating layer) 11a formed corresponding to the non-polarization inversion region 16a of the LiNbO3 substrate 10, and the polarization inversion region 16b of the LiNbO3 substrate 10 is referred to. This is referred to as a second resist (second insulating layer) 11b formed corresponding to the above. The first resist 11a and the second resist 11b extend in the Y direction when one polarization inversion region 16b and non-polarization inversion region 16a are viewed, and as a whole, are spaced apart in a stripe shape in the X direction. It is formed. The film thickness L of the first and second resists 11a and 11b is about 3 μm.

Thereafter, the first and second resists 11a and 11b are softened by a reflow process at 80 ° C. for 30 minutes. As a result, the first and second resists 11a and 11b have a shape having a curved surface above the upper surface 10a of the LiNbO 3 substrate 10 as shown in FIG. 4A. At this time, as shown in FIG. 4B, the film thickness L1 of the first resist 11a is thicker (L1> L2) than the film thickness L2 of the second resist 11b, and the X direction of the second resist 11b. The width Q1 of the first resist 11a is longer than the width Q2 (Q1> Q2). The width Q1 of the first resist 11a is longer than half the pitch Λ of the polarization inversion period (Q1> Λ / 2).
At this time, the size of the opening 11e between the first and second resists 11a and 11b and the width of each of the first and second resists 11a and 11b can be adjusted by the temperature and time of the reflow process. . Then, as shown in FIG. 5, a metal film having a film thickness of about 1 μm is formed on the entire surface from the upper surface 10 a side of the LiNbO 3 substrate 10 by vapor deposition to form the first electrode 12. As the electrode, a conductive material such as Al, Cr, or Ni is used. A second electrode 13 is formed by depositing a metal film on the lower surface (the other surface) 10b of the LiNbO 3 substrate 10 by vapor deposition. Thereby, the first electrode 12 is formed on the first and second resists 11a and 11b and in the opening 11e, and the first electrode 12 in the opening 11e and the upper surface 10a of the LiNbO 3 substrate 10 are in contact with each other. That is, the first electrode 12 and the upper surface 10a of the LiNbO 3 substrate 10 are in contact with each other in the direction along the longitudinal direction (Y direction) of the domain-inverted region 16b.

Then, as shown in FIG. 6, a pulsed voltage is applied between the first electrode 12 and the second electrode 13 by the power supply 15. The applied voltage is, for example, a voltage of 18 kV / mm.
By applying the voltage, as shown in FIG. 7A, polarization inversion starts from the first electrode 12 (on both sides of the second resist 11b) in the opening 11e. Specifically, as shown in FIG. 7B, the end portion of the first electrode 12 between the first and second resists 11a and 11b, that is, the boundary portion between the first electrode 12 and the first resist 11a (hereinafter referred to as “the first electrode 12”). If the edge portion between the first electrode 12 and the second resist 11b is E2, charges concentrate on the edge portions E1 and E2. In one domain-inverted region 16b, the domain-inverted portion A extends from the upper surface 10a of the LiNbO3 substrate 10 to the lower surface 10b (Z direction) from the four portions of the edge portions E1 and E2 between the first and second resists 11a and 11b. And proceed.
Then, as shown in FIG. 8, after the time necessary for the polarization inversion portion A to travel to the lower surface 10 b of the LiNbO 3 substrate 10 has elapsed, the power source 15, for example, between the first electrode 12 and the second electrode 13, A voltage of 21 kV / mm is applied. As a result, the domain-inverted portion A spreads in the lateral direction (X direction) and the domain-inverted region 16b is buried, as shown in FIG. It is formed alternately. At this time, the width P1 of the non-polarization inversion region 16a and the width P2 of the polarization inversion region 16b are the same, that is, the ratio (duty ratio) of the region where the polarization is inverted with respect to the pitch Λ of the polarization inversion period is, for example, About 50%.
After the polarization inversion, the first and second resists 11a and 11b may be removed or left as they are.

  In the method of manufacturing the wavelength conversion element 1 according to the present embodiment, the contact area between the first electrode 12 and the LiNbO 3 substrate 10 is reduced as compared with the conventional case where electrodes are formed on the entire surface of the domain-inverted region 16b. The charges concentrate on the first electrode 12 in contact with the LiNbO 3 substrate 10. As described above, since the charge density in the domain-inverted region 16b is increased, a uniform domain-inverted periodic structure with a duty ratio of 50% can be stably obtained in the plane of the LiNbO3 substrate 10.

In general, the second resist 11b is not provided, the first electrode 12 is formed on the entire surface of the domain-inverted region 16b, and the domain-inverted part A is formed only from the edge part E1, whereas this embodiment As described above, by providing the second resist 11b in the domain-inverted region 16b to form the opening 11e, the domain-inverted portion A is formed from the edge portions E1 and E2. As described above, the polarization inversion portion A is formed from the edge portions E1 and E2 on the upper surface 10a of the LiNbO3 substrate 10, so that the polarization in the direction (X direction) in which the non-polarization inversion region 16a and the polarization inversion region 16b are formed. The amount of spreading of the reversing part A can be reduced. Therefore, the non-uniformity of the polarization inversion portion A in the X direction can be minimized.
Since the wavelength conversion element 1 manufactured by such a manufacturing method has a uniform pitch inversion period Λ between the width P1 of the non-polarization inversion region 16a and the width P2 of the polarization inversion region 16b. The light conversion efficiency is high.
That is, the wavelength conversion element 1 according to the present embodiment can stably apply a voltage to the domain-inverted region 16b in the surface of the LiNbO3 substrate 10, so that the wavelength conversion element 1 with high light conversion efficiency can be obtained. It is possible to manufacture.

Further, since the domain inversion portion A extends in the X direction and the domain inversion region A proceeds to the lower side of the first resist 11a, the width Q1 of the first resist 11a is smaller than the width Q2 of the second resist 11b in the X direction. By making the length longer and making the width Q1 of the first resist 11a longer than half the pitch Λ of the polarization inversion period, a uniform domain inversion periodic structure with a duty ratio of 50% can be obtained.
Further, since the first and second resists 11a and 11b are formed by photolithography and then the first electrode 12 is formed, the first electrode 12 can be formed in the domain-inverted region 16b by a simple method. .
Further, by reducing the film thickness L2 of the second resist 11b having a shorter width Q2 than the width Q1 of the first resist 11a, the first opening 11e between the first resist 11a and the second resist 11b has a first thickness. The electrode 12 is easily deposited. As a result, the first electrode 12 is accurately deposited in the opening 11e, so that a voltage can be more stably applied between the first electrode 12 and the second electrode 13.

Moreover, since the 1st electrode 12 is vapor-deposited after softening the 1st, 2nd resist 11a, 11b by reflow process, the 1st, 2nd resist 11a, 11b inclines toward the opening part 11e. As a result, the first and second resists 11a and 11b do not become shadows when the first electrode 12 is formed, so that the first electrode 12 can be easily deposited in the opening 11e.
Further, the size of the opening 11e between the first resist 11a and the second resist 11b can be adjusted by a step of forming the resist 11 in a predetermined shape by a photolithography method or a reflow processing step. Thereby, the contact area between the first electrode 12 and the upper surface 10a of the LiNbO3 substrate 10 can be adjusted.

In the reflow process, the thicknesses of the first and second resists 11a and 11b formed in the non-polarization inversion region 16a and the polarization inversion region 16b are changed. The height of the first and second resists 11a and 11b may be adjusted by adjusting the conditions of the photolithography method.
Further, the film thicknesses L1 and L2 of the first and second resists 11a and 11b of the non-polarized inversion region 16a and the polarization inversion region 16b are not necessarily different, and may be the same.

Further, after the reflow treatment step shown in FIG. 4, a liquid electrode containing NaCl (sodium chloride) may be used as shown in FIG. That is, it has the 1st accommodating part 17 which forms the 1st space containing the 1st, 2nd resist 11a, 11b, and the 2nd accommodating part 18 which forms the space containing the lower surface 10b of the LiNbO3 board | substrate 10. FIG. The first and second storage portions 17 and 18 are filled with a first NaCl solution 19a and a second NaCl solution 19b, respectively. Further, the first NaCl solution 19a is prevented from leaking outside the first housing portion 17 by an O-ring 14a provided on the surface where the first housing portion 17 and the upper surface 10a face each other. Further, the second NaCl solution 19b is prevented from leaking out of the second accommodating portion 18 by an O-ring 14b provided on the surface where the second accommodating portion 18 and the lower surface 10b face each other.
Furthermore, a first electrode 20 a is provided on the inner surface 17 a of the first housing part 17, and a second electrode 20 b is provided on the inner surface 18 a of the second housing part 18.
With this configuration, by applying a pulse voltage between the first electrode 20a and the second electrode 20b by the power supply 15, the first NaCl solution 19a is formed on the upper surface 10a where the opening 11e of the LiNbO3 substrate 10 is formed. Is applied to the lower surface 10b of the LiNbO 3 substrate 10 via the second NaCl solution 19b. In this way, as shown in FIG. 9, the non-polarization inversion regions 16a and the polarization inversion regions 16b are alternately formed.

[Modification of First Embodiment]
In the first embodiment shown in FIG. 4, the first and second resists 11a and 11b are completely separated and formed in a stripe shape in the X direction. However, as shown in FIG. A cross-sectional view wave type configuration having a film thickness distribution in which the resists 21a and 21b are continuously formed may be used. Such a modification will be described with reference to FIG.

  In this configuration, the thickness distribution of the resist is such that the thickness of the second resist 21b in the domain-inverted region 16b is thinner than the thickness of the first resist 21a in the non-domain-inverted region 16a. Specifically, the thinnest part of the film thickness distribution is in contact with the upper surface 10 a of the LiNbO 3 substrate 10. As a result, as shown in FIG. 11, the end of the first electrode 12, that is, the edge (boundary portion) Ea between the first electrode 12 and the first resist 21a, the first electrode 12 and the second resist 21b, The edge portion (boundary portion) Ea is at the same position. The distance between the first and second resists 21a and 21b and the conditions of the reflow process should be optimized so that the adjacent resists 21a and 21b come into contact with each other during the reflow process. Formed with. For example, the first and second resists 21a, 21b adjacent to each other can be obtained by performing a reflow process by setting the interval between the adjacent first and second resists 21a, 21b to 0.3 μm to 0.5 μm by photolithography. 21b can be contacted. Then, the first electrode 12 is formed in the recess 11f thus formed and on the first and second resists 21a and 21b.

Therefore, in the above-described embodiment, the domain-inverted regions 16b are formed in the domain-inverted regions 16b from the four edge portions E1 and E2, but in the configuration shown in FIG. 11, the upper surface 10a of the LiNbO 3 substrate 10 and the first electrode 12 Since this is a line contact, the domain-inverted regions 16b are formed in the domain-inverted regions 16b from the two edge portions Ea. Thereby, the contrast of the electric field between the domain-inverted region 16b and the non-domain-inverted region 16a can be improved, so that the domain-inverted region 16b can be easily formed.
The first electrode 12 is not necessarily in contact with the upper surface 10a of the LiNbO 3 substrate 10. In this configuration, the domain-inverted region 16b can be obtained by increasing the voltage applied between the first electrode 12 and the second electrode 13.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described with reference to FIGS. Note that, in the drawings of the respective embodiments described below, the same reference numerals are given to portions that share the same manufacturing method and configuration of the wavelength conversion element 1 according to the first embodiment described above, and the description thereof will be omitted. .
In the method for manufacturing the wavelength conversion element 1 according to the present embodiment, a plurality of openings 32 are formed along the direction (Y direction) intersecting the polarization inversion periodic direction (X direction) of the upper surface 10a of the LiNbO 3 substrate 10. This is different from the first embodiment. Other configurations are the same as those of the first embodiment.

Next, a method for manufacturing the wavelength conversion element 1 according to the present invention will be described with reference to FIGS.
FIG. 12 is a main part sectional view showing a state in which an insulating layer is formed on the nonlinear optical member, and FIG. 13 is a main part sectional view showing a state in which the insulating layer is formed into a predetermined shape by photolithography. 14 (a) is a top view showing a state after the reflow treatment, FIG. 14 (b) is a cross-sectional view taken along line BB in FIG. 14 (a), and FIG. It is a top view which shows the polarization inversion area | region of a nonlinear optical member, FIG.15 (b) is sectional drawing in the BB line arrow of Fig.15 (a), FIG. 16 is a top view which shows a polarization inversion periodic structure It is. FIG. 15A shows only the first electrode 41 in contact with the upper surface 10 a of the LiNbO 3 substrate 10.

First, as in the first embodiment, as shown in FIG. 12, a resist (insulating layer) 31 is applied to the upper surface 10a of the LiNbO 3 substrate 10.
Then, using photolithography, as shown in FIG. 13, openings 32 are formed in the resist 31 at intervals along the Y direction of the domain-inverted regions 36b.
Thereafter, the resist 31 is softened by a reflow process at 80 ° C. for 30 minutes, and the resist 31 between the openings 32 is formed in a mountain shape as shown in FIG. At this time, as shown in FIG. 14, if the interval between adjacent openings 32 is i (the length of the resist 31 in the Y direction) and the width of the opening 32 in the X direction is w, the relationship of w> i is satisfied. It holds. The shape of the opening 32 of the resist 31 is an ellipse that is long in the Y direction.

Then, as shown in FIG. 15A, the first electrode 41 formed in the opening 32 is deposited on the entire upper surface 10 a of the LiNbO 3 substrate 10, so that the first electrode 41 formed in the opening 32 is the upper surface of the LiNbO 3 substrate 10. 10a is contacted. That is, the first electrodes 41 are formed in a plurality of rows in a stepping stone shape at predetermined intervals in the arrangement direction (Y direction) of the openings 32. The first electrodes 41 are arranged on the same straight line in the two-dimensional direction of the X direction and the Y direction.
The width w of the opening 32 is the width of the first electrode 41, and the interval i between the openings 32 is the interval between the first electrodes 41. Further, the second electrode 42 is also deposited on the lower surface 10 b of the LiNbO 3 substrate 10.
Thereafter, a pulsed voltage is applied between the first electrode 41 and the second electrode 42 by a power source (not shown). Accordingly, as shown in FIGS. 15A and 15B, the end portion of the first electrode 41, that is, the boundary portion between the first electrode 41 and the resist 31 becomes the edge portion E1, and this edge portion E1. Electric charge concentrates on. Then, as shown in FIG. 15B, in the domain-inverted region 36b, the domain-inverted portion A from the edge portion E1 proceeds from the upper surface 10a of the LiNbO 3 substrate 10 toward the lower surface 10b. Then, when the polarization inversion portion A proceeds to the lower surface 10b of the LiNbO3 substrate 10, it spreads in the in-plane direction of the LiNbO3 substrate 10, that is, the arrangement direction (Y direction) of the first electrodes 41. Thereby, the adjacent polarization inversion portions A generated from the edge portion E1 are connected, and the polarization inversion region 16b is formed in the arrangement direction of the first electrodes 41 as shown in FIG.

In the manufacturing method of the wavelength conversion element 1 according to the present embodiment, the first electrode 41 is provided in a stepping stone shape in the domain-inverted region 36b, so that an electrode is formed on the entire surface of the domain-inverted region 36b as in the conventional case. The contact area between the first electrode 41 and the LiNbO 3 substrate 10 is reduced. As a result, charges concentrate on the boundary portion between the first electrode 41 and the resist 31, that is, the edge portion E1. In addition, since edge portions increase in the X direction and the Y direction as compared with the first embodiment, the charge density increases in the domain-inverted region 36b. Therefore, the duty ratio is 50% in the plane of the LiNbO 3 substrate 10. A uniform domain-inverted periodic structure can be obtained.
In addition, since the first electrode 41 is deposited after the resist 31 is dissolved by the reflow process, the resist 31 is inclined toward the opening 32, so that the resist 31 is shaded when the first electrode 41 is formed. Instead, the first electrode 41 can be easily deposited in the opening 32.

[Modification of Second Embodiment]
In the second embodiment shown in FIG. 15A, the first electrodes 41 are arranged on the same straight line in the two-dimensional direction of the X direction and the Y direction. It may be a staggered arrangement shifted in the direction. Such a modification will be described with reference to FIGS. This modification is effective when a voltage is applied between the first electrode 41 and the second electrode 42, and when the adjacent polarization inversion portions A generated from the edge portion E1 are not connected to each other, a straight line is not formed in the Y direction. It is.

As shown in FIG. 17, in the first electrode 41 of the present modification, a plurality of first electrodes 41 arranged in the X direction are arranged so as to be shifted in the Y direction with respect to the first electrodes 41 adjacent to each other in a row. . Specifically, the adjacent first electrodes 41 are arranged so as to be shifted in the Y direction by a half of the pitch in the direction intersecting the polarization inversion direction of the first electrodes 41. FIG. 17 shows only the first electrode 41 in contact with the upper surface 10a of the LiNbO 3 substrate 10.
In this modification, when a voltage is applied between the first electrode 41 and the second electrode 42, the polarization inversion portion A is connected to the end of the first electrode 41 as in the second embodiment as shown in FIG. This occurs from the edge portion E1 that is the boundary portion between the first electrode 41 and the resist 31. And after the polarization inversion part A advances to a Z direction from XY plane, as shown in FIG. 19, the adjacent polarization inversion part A is connected. At this time, the boundary portion D between the non-polarization inversion region 16 a and the polarization inversion region 16 b draws a curve along the elliptical shape of the first electrode 41.

Here, as in the second embodiment, when the first electrode 41 is formed on the same straight line in the X direction and the Y direction, and the polarization inversion proceeds along the shape of the first electrode 41, the X direction The width T1 of the non-polarization inversion region 16a and the width T2 of the polarization inversion region 16b are not constant in the Y direction.
At this time, by forming the first electrodes 41 in a staggered arrangement as in this modification, the width T2 in the X direction of the domain inversion region 16b increases or decreases in the Y direction. The width T1 in the X direction of 16a is constant in the Y direction. Thereby, the same period is ensured by causing light to enter the position where the width T2 in the X direction of the domain-inverted region 16b is the same as the width T1 of the non-domain-inverted region 16a. That is, in this modification, even when the width T2 of the domain-inverted region 16b is different in the Y direction, by adjusting the incident position where the light is incident on the wavelength conversion element 1, light can be relatively efficiently applied to the region satisfying the phase matching. Is easily incident.

[Third Embodiment: Light Source Device]
Next, a third embodiment will be described. In the present embodiment, an example of a light source device including a wavelength conversion element manufactured by the wavelength conversion element manufacturing method described in each of the above-described embodiments will be described.
FIG. 20 is a schematic configuration diagram illustrating the light source device 100 according to the present embodiment. As illustrated in FIG. 20, the light source device 100 includes a light source 101 that emits infrared light, a wavelength conversion element 1 manufactured by the wavelength conversion element manufacturing method according to the first embodiment, and a wavelength selection element 102. ing.
A wavelength conversion element 1 (second harmonic generation element, SHG: Second Harmonic Generation) is an element that converts light W1 emitted from the light source 101 (solid line shown in FIG. 20) into a predetermined wavelength, and substantially converts incident light. It is a nonlinear optical element that converts to a half wavelength.
Further, as shown in FIG. 20, the wavelength selection element 102 selects the laser light W2 (a chain line shown in FIG. 20) having a predetermined selection wavelength emitted from the wavelength conversion element 1 and reflects it toward the light source 101. Functions as a resonator mirror of the light source 101 and transmits the converted laser beam W3 (two-dot chain line shown in FIG. 20). As the wavelength selection element 102, for example, an optical element such as a hologram having a periodic grating can be used.
According to the light source device 100 configured as described above, since the wavelength conversion element 1 having high light conversion efficiency is provided, the light use efficiency of the entire device can be improved.
Although the light source device 100 of the present embodiment is configured to include the wavelength selection element 102, the wavelength selection element 102 is not necessarily provided when the light source 101 has a resonator structure.

[Fourth Embodiment: Lighting Device]
Next, a fourth embodiment will be described. In this embodiment, an example of an illumination device to which the light source device described in the above embodiment is applied will be described.
FIG. 21 is a schematic configuration diagram showing the illumination device 200 according to the present embodiment. As shown in FIG. 21, the illumination device 200 includes the light source device 100 described in the third embodiment. The light source device 100 includes a light source 101, a wavelength conversion element 1, a wavelength selection element 102, and a diffusion plate 210.
According to the illumination device 200 configured as described above, since the light source device 100 capable of reducing the occurrence of scintillation is provided, the illumination device 200 itself can also reduce the occurrence of scintillation.

[Fifth Embodiment: Projector]
Next, a fifth embodiment will be described. In this embodiment, an example of a projector to which the light source device described in the above embodiment is applied will be described.
In the projector 300 of this embodiment, as shown in FIG. 22, a reflection type screen 350 is used, and light including image information is projected onto the screen 350 from the front side of the screen 350.
As shown in FIG. 22, the projector 300 includes the light source device 100, a light modulation device (light modulation unit) 320, a dichroic prism (color synthesis unit) 330, and a projection device 340.
The light source device 100 includes a red light source device (light source) 100R that emits red light, a green light source device (light source) 100G according to the third embodiment that emits green light, and a blue light source according to the third embodiment that emits blue light. Device (light source) 100B.

In addition, the liquid crystal light valve 320 uses the two-dimensional red light modulation device 320R that modulates light emitted from the red light source device 100R according to image information, and the light emitted from the green light source device 100G as image information. A two-dimensional green light modulation device 320G that performs light modulation in response to the light and a two-dimensional blue light modulation device 320B that light-modulates light emitted from the blue light source device 100B according to image information. Furthermore, the dichroic prism 330 synthesizes each color light modulated by each light modulator 320R, 320G, 320B.
Further, in order to make the illuminance distribution of the light emitted from each light source device 100R, 100G, 100B uniform, uniform optical systems 302R, 302G, 302B are provided on the downstream side of the light path from each light source device 100R, 100G, 100B. Thus, the liquid crystal light valves 320R, 320G, and 320B are illuminated with light having a uniform illuminance distribution. For example, the uniformizing optical systems 302R, 302G, and 302B are configured by, for example, a hologram 302a and a field lens 303b.
The projection device 340 projects the light synthesized by the dichroic prism 330 onto the screen 350.

According to the projector 300 configured as described above, since the light source devices 100R, 100G, and 100B having high light use efficiency are provided, a bright and clear image can be projected onto the screen 350.
The red light source device 100R uses a light source device that emits red light (visible light), but the light source 101 that emits infrared light as in the light source device 100 described in the third embodiment. A light source device that converts the wavelength of light emitted from the light source 101 may be used.
Further, the light source device 100 according to the third embodiment can be applied not only to the projector 300 but also to a scanning image display device.

[Sixth Embodiment: Monitor Device]
Next, a configuration example of the monitor device 400 to which the light source device 100 according to the third embodiment is applied will be described. FIG. 23 is a schematic diagram illustrating an outline of a monitor device. The monitor device 400 includes a device main body 410 and an optical transmission unit 420.

  The light transmission unit 420 includes two light guides 421 and 422 on the light sending side and the light receiving side. Each of the light guides 421 and 422 is a bundle of a large number of optical fibers, and can send laser light to a distant place. The light source device 100 is disposed on the incident side of the light guide 421 on the light transmitting side, and the diffusion plate 423 is disposed on the emission side thereof. The laser light emitted from the light source device 100 is transmitted to the diffusion plate 423 provided at the tip of the light transmission unit 420 through the light guide 421 and is diffused by the diffusion plate 423 to irradiate the subject.

  An imaging lens 424 is also provided at the tip of the light transmission unit 420, and reflected light from the subject can be received by the imaging lens 424. The received reflected light travels through the light guide 422 on the receiving side and is sent to a camera 411 as an imaging means provided in the apparatus main body 410. As a result, the camera 411 can capture an image based on the reflected light obtained by irradiating the subject with the laser light emitted from the light source device 100.

  According to the monitor device 400 configured as described above, since the subject can be irradiated by the light source device 100 with high light use efficiency, the brightness of the captured image obtained by the camera 411 can be increased.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, although a cross dichroic prism is used as the color light combining means, the present invention is not limited to this. As the color light synthesizing means, for example, a dichroic mirror having a cross arrangement to synthesize color light, or a dichroic mirror arranged in parallel to synthesize color light can be used.
Further, the second electrode is formed on the entire lower surface of the LiNbO 3 substrate, but an electrode having the same shape as the first electrode may be provided at a position corresponding to the first electrode on the lower surface of the LiNbO 3 substrate.

It is a perspective view showing the wavelength conversion element concerning a 1st embodiment of the present invention. It is a figure which shows the manufacturing method of the wavelength conversion element of FIG. It is a figure which shows the manufacturing method of the wavelength conversion element of FIG. It is a figure which shows the manufacturing method of the wavelength conversion element of FIG. It is a figure which shows the manufacturing method of the wavelength conversion element of FIG. It is a figure which shows the manufacturing method of the wavelength conversion element of FIG. It is a figure which shows the manufacturing method of the wavelength conversion element of FIG. It is a figure which shows the manufacturing method of the wavelength conversion element of FIG. It is a figure which shows the manufacturing method of the wavelength conversion element of FIG. It is a figure which shows the modification of the manufacturing method of the wavelength conversion element of FIG. It is a figure which shows the modification of the shape of the insulating layer shown in FIG. It is a figure which shows the manufacturing method of the wavelength conversion element which concerns on 2nd Embodiment of this invention. It is a figure which shows the manufacturing method of a wavelength conversion element. It is a figure which shows the manufacturing method of a wavelength conversion element. It is a figure which shows the manufacturing method of a wavelength conversion element. It is a figure which shows the manufacturing method of a wavelength conversion element. It is a figure which shows the modification of the manufacturing method of the wavelength conversion element which concerns on 2nd Embodiment of this invention. It is a figure which shows the manufacturing method of a wavelength conversion element. It is a figure which shows the manufacturing method of a wavelength conversion element. It is a top view which shows the light source device which concerns on 3rd Embodiment of this invention. It is a perspective view which shows the illuminating device which concerns on 4th Embodiment of this invention. It is a top view which shows the projector which concerns on 5th Embodiment of this invention. It is a top view which shows the monitor apparatus which concerns on 6th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Wavelength conversion element, 10 ... LiNbO3 board | substrate (nonlinear optical member), 10a ... Upper surface (one surface), 10b ... Lower surface (the other surface), 11 ... Resist (insulating layer), 11a ... 1st resist (1st Insulating layer), 11b ... second resist (second insulating layer), 12 ... first electrode, 13 ... second electrode, 100 ... light source device, 102 ... wavelength selection element, 200 ... illumination device, 300 ... projector, 320 ... Light modulation device (light modulation means), 400 ... monitor device, 411 ... camera (imaging means)

Claims (12)

A method for manufacturing a wavelength conversion element having a polarization inversion periodic structure in which polarization inversion regions and non-polarization inversion regions are alternately arranged,
Forming an insulating layer having openings at a predetermined interval in a part of a region to be the domain-inverted region on one surface of the nonlinear optical member;
Providing a first electrode on the insulating layer including the inside of the opening, and providing a second electrode on the other surface opposite to the one surface of the nonlinear optical member;
And a step of applying a voltage that reverses the polarization of the nonlinear optical member between the first electrode and the second electrode.   2. The method of manufacturing a wavelength conversion element according to claim 1, wherein a plurality of the openings are formed in one of the polarization inversion regions in a direction intersecting with the polarization inversion period direction of the nonlinear optical member.   An interval between the first electrodes formed in the adjacent openings in a direction crossing the polarization inversion period direction is smaller than the dimension of the first electrode in the domain inversion period direction, and the pitch of the first electrodes is 3. The method for manufacturing a wavelength conversion element according to claim 1, wherein the wavelength conversion element is smaller than a half dimension.   The first electrodes formed in the openings arranged in a direction crossing the polarization inversion period direction are shifted in the arrangement direction of the openings for each column in the polarization inversion period direction. The manufacturing method of the wavelength conversion element of any one of Claim 2 or Claim 3. In the step of forming the insulating layer, a first insulating layer is formed in the non-polarization inversion region and a second insulating layer is provided in the polarization inversion region at a predetermined interval in a direction of polarization inversion of the nonlinear optical member. Formed,
2. A dimension of the first insulative layer in a direction of polarization inversion period is larger than a dimension of the second insulative layer in a direction of domain inversion period and is larger than half of a pitch of the domain inversion period. The manufacturing method of the wavelength conversion element of any one of Claim 4. A method for manufacturing a wavelength conversion element having a polarization inversion periodic structure in which polarization inversion regions and non-polarization inversion regions are alternately arranged,
Forming an insulating layer having a thickness smaller than the thickness of the non-polarization inversion region in a region serving as the polarization inversion region in the direction of polarization inversion period of one surface of the nonlinear optical member;
Forming a first electrode on the insulating layer and forming a second electrode on the other surface opposite to the one surface of the nonlinear optical member;
And a step of applying a voltage that reverses the polarization of the nonlinear optical member between the first electrode and the second electrode. Using a resin material as the material of the insulating layer,
The method for manufacturing a wavelength conversion element according to any one of claims 1 to 6, wherein the step of forming the insulating layer includes a reflow step of heating and melting the insulating layer.   A wavelength conversion element manufactured by the method for manufacturing a wavelength conversion element according to any one of claims 1 to 7. A light source that emits light;
A light source device comprising: the wavelength conversion element according to claim 8, which converts a wavelength of light emitted from the light source into a predetermined wavelength.   An illumination device comprising the light source device according to claim 9. The light source device according to claim 9;
Light modulating means for modulating light emitted from the light source device;
A projector comprising: a projection device that projects light modulated by the light modulation means. The light source device according to claim 9;
A monitor device comprising: imaging means for imaging a subject by light emitted from the light source device.

Images