Wavelength conversion device and lighting device

Abstract

The present invention has: a flat plate-shaped phosphor portion including a phosphor excited by excitation light to emit fluorescence; a first nano antenna group including a plurality of metal first nano antennas disposed on a lower surface side of the phosphor portion and each arranged at a first period; a translucent body including a translucent material embedded between each adjacent first nanoantennas and formed on a lower surface of the phosphor portion so as to cover the lower surface of the phosphor portion; and a second nano antenna group including a plurality of metal second nano antennas disposed on the upper surface of the phosphor portion and each disposed on the upper surface of the phosphor portion at a second period.

Description

Technical Field

[0001] The invention relates to a wavelength conversion device and a lighting device. Background Art

[0002] A lighting device has been disclosed that uses a metal antenna made of nano-sized metal particles (hereinafter referred to as a nanoantenna) to narrow the angle of fluorescence. For example, Patent Document 1 discloses a lighting device that includes a first wavelength conversion layer, an antenna array formed on an upper surface of the first wavelength conversion layer and including a plurality of nanoantennas, and a second wavelength conversion layer formed on the upper surface of the first wavelength conversion layer while filling the nanoantenna array.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2016-535304. Summary of the invention

[0004] Technical issues

[0005] In the lighting device disclosed in Patent Document 1, the traveling direction of the fluorescence generated in the first wavelength conversion layer and reaching the nanoantenna is determined according to the light diffraction conditions determined by the arrangement of the nanoantennas, etc. With respect to the fluorescence reaching the nanoantennas and then returning to the inside of the first wavelength conversion layer according to the diffraction conditions, there is a problem that the fluorescence propagates inside the wavelength conversion layer and then reaches the lower surface or the side end surface and is emitted therefrom or absorbed by the nanoantenna, so that the fluorescence cannot be extracted from the lighting device.

[0006] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a wavelength conversion device and a lighting device capable of increasing fluorescence extracted from a wavelength conversion layer to improve light extraction efficiency.

[0007] Technical Solution

[0008] The wavelength conversion device according to the present invention includes: a flat-plate-shaped phosphor portion, a first nano-antenna group, a translucent main body portion, and a second nano-antenna group. The flat-plate-shaped phosphor portion includes a phosphor that is excited by excitation light to emit fluorescence. The first nano-antenna group is arranged on the lower surface side of the phosphor portion and includes a plurality of first nano-antennas. The corresponding plurality of first nano-antennas are made of metal arranged at a first pitch. The translucent main body portion is filled between adjacent first nano-antennas, is formed on the lower surface of the phosphor portion to cover the lower surface of the phosphor portion, and is made of a translucent material. The second nano-antenna group is arranged on the upper surface of the phosphor portion and includes a plurality of second nano-antennas. The corresponding plurality of second nano-antennas are made of metal arranged at a second pitch on the upper surface of the phosphor portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1is a top view of the wavelength conversion device according to the first embodiment.

[0010] Figure 2 is a cross-sectional view of the wavelength conversion device according to the first embodiment.

[0011] Figure 3 : is a graph showing the transmission diffraction angle of fluorescence with respect to the incident angle in the wavelength conversion device according to the first embodiment.

[0012] Figure 4 is a graph showing the percentage of the transmission intensity of fluorescent light relative to the incident angle in the wavelength conversion device according to the first embodiment.

[0013] Figure 5 : is a graph showing the reflection intensity of fluorescence with respect to the arrangement pitch of nano-antennas in the wavelength conversion device according to the first embodiment.

[0014] Figure 6 : is a graph showing the transmission intensity of fluorescence with respect to the tilt angle of the nano-antenna in the wavelength conversion device according to the first embodiment.

[0015] Figure 7 : is a graph showing the reflection intensity of fluorescence with respect to the tilt angle of the nano-antenna in the wavelength conversion device according to the first embodiment.

[0016] Figure 8 is a cross-sectional view of a lighting device according to a second embodiment.

[0017] Fig. 9 is a cross-sectional view of a wavelength conversion device according to a second embodiment.

[0018] Fig.10 is a cross-sectional view of a lighting device according to a third embodiment.

[0019] Fig.11 is a cross-sectional view of a wavelength conversion device according to a third embodiment. DETAILED DESCRIPTION

[0020] Embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals are attached to the same components, and explanations of overlapping components will be omitted.

[0021] First embodiment

[0022] Reference Figure 1 and Figure 2 , describes the configuration of the wavelength conversion device 100 according to the first embodiment. Figure 1 is a top view of the wavelength conversion device 100 according to the first embodiment. Figure 2 is along Figure 1A cross-sectional view of the wavelength conversion device 100 is shown along line 2-2.

[0023] According to the first embodiment, the wavelength conversion device 100 includes a phosphor portion excited by excitation light to emit fluorescence, a first nanoantenna group including a plurality of first nanoantennas arranged on the lower surface side of the phosphor portion, a translucent main body portion filled between adjacent first nanoantennas, formed on the lower surface of the phosphor portion to cover the lower surface of the phosphor portion and made of a translucent material, and a second nanoantenna group including a plurality of second nanoantennas arranged at the upper surface of the phosphor portion.

[0024] [Mounting substrate]

[0025] The mounting substrate 12 is an insulating flat plate-like substrate having a rectangular upper surface shape. The mounting substrate 12 is made of, for example, aluminum nitride (AlN), aluminum oxide (Al2O3), etc. Hereinafter, for convenience of explanation, the X-axis, Y-axis, and Z-axis are defined by taking the direction perpendicular to the upper surface of the mounting substrate 12 as the Z-axis, and taking the directions along the respective two sides perpendicular to each other of the mounting substrate 12 as the X-axis and the Y-axis.

[0026] [Light-emitting element]

[0027] The light emitting element 13 is a light emitting diode (LED) mounted on the upper surface of the mounting substrate 12 and having a rectangular upper surface shape. The light emitting element 13 includes a semiconductor structure layer 14 having a light emitting layer, a support substrate 15 disposed on the upper surface of the semiconductor structure layer 14, and a p-electrode 16 and an n-electrode 17 disposed on the lower surface of the semiconductor structure layer 14 and bonded to the mounting substrate 12. That is, the light emitting element 13 is flip-chip mounted to the mounting substrate 12.

[0028] The semiconductor structure layer 14 is a semiconductor stack including an n-type semiconductor layer, a light-emitting layer and a p-type semiconductor layer (all not shown) each containing gallium nitride (GaN) as a main material. When the light-emitting element 13 is driven, the light-emitting layer of the semiconductor structure layer 14 emits blue light with a peak wavelength of 450nm.

[0029] The support substrate 15 is a flat plate-like substrate having a rectangular upper surface shape. The support substrate 15 is made of a material such as single crystal sapphire (Al2O3) that is translucent to the blue light emitted from the semiconductor structure layer 14. The upper surface of the support substrate 15 is a light emitting surface from which the light emitting element 13 emits blue light, which is emitted from the light emitting layer of the semiconductor structure layer 14.

[0030] The p-electrode 16 is an electrode electrically connected to the p-type semiconductor layer of the semiconductor structure layer 14. The p-electrode 16 is bonded to a p-side wiring (not shown) formed on the upper surface of the mounting substrate 12 via a conductive bonding member (not shown).

[0031] The n-electrode 17 is an electrode electrically connected to the n-type semiconductor layer via a through electrode (not shown) that penetrates the light emitting layer and the p-type semiconductor layer of the semiconductor structure layer 14 in the up-down direction and has a side surface covered with an insulator. In other words, the n-electrode 17 is electrically connected only to the n-type semiconductor layer and is insulated from the light emitting layer and the p-type semiconductor layer. The n-electrode 17 is bonded to an n-side wiring (not shown) formed on the upper surface of the mounting substrate 12 via a conductive bonding member (not shown).

[0032] As described above, the light emitting element 13 has a structure that emits blue light generated by applying a voltage to the p-electrode 16 and the n-electrode 17 via the mounting substrate 12 to cause a current to flow from the upper surface of the supporting substrate 15 through the semiconductor structure layer 14 .

[0033] [First translucent part]

[0034] The first semitransparent portion 19 is a flat plate-shaped portion formed on the upper surface of the light emitting element 13 (ie, the upper surface of the supporting substrate 15). In this embodiment, the first semitransparent portion 19 is described as a portion made of sapphire.

[0035] The first translucent portion 19 has the same planar shape as the support substrate 15, and in a top view from above the wavelength conversion device 100, that is, in a top view viewed in the direction along the Z direction, the outer edge of the first translucent portion 19 overlaps with the outer edge of the support substrate 15. The lower surface of the first translucent portion 19 is bonded to the upper surface of the support substrate 15 via a translucent bonding material (not shown). The first translucent portion 19 is formed to have a thickness of 500 μm or less, and particularly preferably, is formed to have a thickness of 100 μm or less.

[0036] The material of the first semi-transparent portion 19 only needs to be a material having semi-transparency to the blue light emitted from the light emitting element 13 , and may be quartz or AlN.

[0037] [Second translucent part]

[0038] The second semitransparent portion 21 is a portion formed on the upper surface of the first semitransparent portion 19, and includes a first nanoantenna 22 and a semitransparent body portion 23. The second semitransparent portion 21 is formed to have a thickness of 1000 nm or less, and particularly preferably, is formed to have a thickness of 500 nm or less.

[0039] The first nano-antennas 22 are conical metal bodies each formed on the upper surface of the first translucent portion 19. A plurality of first nano-antennas 22 are arranged in a square grid pattern at a first pitch P1 along each of the X direction and the Y direction on the upper surface of the first translucent portion 19, thereby forming a first nano-antenna group 22A. The first pitch P1 is a pitch smaller than the peak wavelength of fluorescence emitted from the phosphor portion 24 described later, and is preferably 500 nm or less.

[0040] Each first nanoantenna 22 is configured of a material having a plasma frequency in the visible light region, such as Au (gold), Ag (silver), Cu (copper), Pt (platinum), Pd (palladium), Al (aluminum), and Ni (nickel), and an alloy or a laminate containing them. In particular, each first nanoantenna 22 is preferably configured of a metal such as aluminum (Al) and copper (Ag) having low absorption in the visible light region.

[0041] The semi-transparent body part 23 is a semi-transparent film body formed to cover the upper surface of the first semi-transparent part 19 and fill between the adjacent first nano-antennas 22. In this embodiment, the semi-transparent body part 23 is described as a semi-transparent body part formed of a SiO2 film. The material of the semi-transparent body part 23 only needs to be a material having semi-transparency to the blue light emitted from the light emitting element 13.

[0042] exist Figure 2 In the figure, although the translucent main body portion 23 is shown to completely cover the first nanoantenna 22, that is, it is shown so that the upper surface of the translucent main body portion 23 is spaced apart from the upper end of the first nanoantenna 22, the upper end of the first nanoantenna 22 can be in contact with the upper surface of the translucent main body portion 23.

[0043] In this embodiment, the above-mentioned first translucent portion 19 may be provided as needed, and the second translucent portion 21 may be formed on the upper surface of the support substrate 15 of the light emitting element 13 without providing the first translucent portion 19. That is, a configuration in which the first nano-antenna 22 and the translucent body portion 23 are provided on the upper surface of the support substrate 15 to form the second translucent portion 21 may be adopted.

[0044] [Phosphor section]

[0045] The phosphor portion 24 is a flat phosphor plate bonded to the upper surface of the second translucent portion 21, having a thickness of 50 μm to 250 μm, and having a rectangular upper surface shape. The phosphor portion 24 has the same planar shape as the light emitting element 13 and the second translucent portion 21, and in a top view viewed in the direction along the Z direction, the outer edge of the phosphor portion 24 overlaps the outer edge of the second translucent portion 21.

[0046] The phosphor section 24 is made of phosphor excited by blue light emitted from the light emitting element 13 to emit yellow fluorescence. Specifically, the phosphor section 24 is, for example, a single crystal ceramic phosphor plate made of yttrium aluminum garnet phosphor (YAG:Ce) activated with cerium (Ce).

[0047] Although the phosphor portion 24 is not limited to a phosphor plate configured only by a single crystal YAG:Ce phosphor, the phosphor portion 24 preferably has a configuration in which scattering is less likely to occur inside, preferably a single-phase phosphor plate made of a single material, and in this case, may be polycrystalline. The yellow fluorescence emitted from the phosphor has a peak wavelength of 520nm to 570nm, and has a yellow emission spectrum with a broad peak of 480nm to 700nm.

[0048] When blue light as excitation light emitted from the light emitting surface of light emitting element 13 is incident on phosphor portion 24 , a portion of the excitation light directly passes through phosphor portion 24 , and another portion of the excitation light excites the phosphor to cause the excited phosphor to emit yellow fluorescence.

[0049] Therefore, the excitation light (blue light) that has passed through the phosphor portion 24 and does not contribute to the generation of fluorescence and the fluorescence (yellow light) emitted from the phosphor are emitted from the upper surface of the phosphor portion 24. Therefore, white light in which the yellow fluorescence emitted from the upper surface of the phosphor portion 24 and the blue light are mixed is extracted from the wavelength conversion device 100.

[0050] [Second Nanoantenna]

[0051] The second nano-antennas 25 are conical metal bodies each formed on the upper surface of the phosphor portion 24. A plurality of second nano-antennas 25 are arranged in a square grid pattern at a second pitch P2 along each of the X and Y directions on the upper surface of the phosphor portion 24, thereby forming a second nano-antenna group 25A.

[0052] The second pitch P2 is a pitch smaller than the peak wavelength of the fluorescence emitted from the phosphor portion 24, and is preferably 500 nm or less. In this embodiment, the above-mentioned first pitch P1 is equal to or smaller than the second pitch P2.

[0053] Each of the second nano-antennas 25 is configured of a material such as Au, Ag, Cu, Pt, Pd, Al, and Ni having a plasma frequency in the visible light region, and an alloy or a laminate containing them. In particular, each second nano-antenna 25 is preferably configured of a metal such as Al and Ag having low absorption in the visible light region.

[0054] Figure 1 and Figure 2The arrangement of the first nano-antenna 22 and the second nano-antenna 25 is only schematically shown for describing the first nano-antenna 22 and the second nano-antenna 25. In practice, the light emitting element 13 is, for example, 1 square millimeter (mm square), and in this case, the number of the first nano-antenna 22 and the second nano-antenna 25 is greater than Figure 1 and Figure 2 Quantity shown.

[0055] [Light reflecting member]

[0056] The light reflecting member 26 is a member having light reflectivity, which continuously extends to cover the respective outer surfaces of the semiconductor structure layer 14 and the supporting substrate 15 of the light emitting element 13, the first translucent portion 19, the second translucent portion 21, and the phosphor portion 24. The light reflecting member 26 is configured of a translucent resin containing light scattering particles, and is made of, for example, a resin material in which titanium oxide (TiO2) particles are contained in a silicone resin.

[0057] The light reflecting member 26 suppresses the excitation light emitted from the light emitting element 13 and the fluorescence generated in the phosphor portion 24 from being emitted from the outer surface of the wavelength conversion device 100 due to the light reflectivity.

[0058] The following reference Figure 2 The improvement of the light extraction efficiency of the wavelength conversion device 100 of this embodiment is described. Figure 2 , the solid line indicates the fluorescent light emitted from the upper surface of the phosphor portion 24 , and the dashed-dotted line indicates the fluorescent light traveling inside the phosphor portion 24 .

[0059] Hereinafter, among the lights emitted from the light emitting surface of the wavelength conversion device 100 (in other words, the upper surface of the phosphor portion 24), the fluorescence emitted at an angle of 30 degrees or less relative to a straight line perpendicular to the upper surface is referred to as narrow-angle fluorescence or narrow-angle light. The light extraction efficiency of the narrow-angle light is described as the light extraction efficiency of the wavelength conversion device 100.

[0060] The traveling direction of the fluorescent light generated in the phosphor portion 24 and reaching the second nanoantenna 25 is determined according to a light diffraction condition determined by the refractive indexes of the phosphor portion 24 and air and the second pitch P2 of the second nanoantenna 25 .

[0061] When fluorescence is extracted according to light diffraction conditions, the diffraction angle θ1 is determined by the incident angle θ2 of the fluorescence reaching the upper surface of the phosphor portion 24 from the inside of the phosphor portion 24, and the diffraction angle θ1 is the angle between a vertical line perpendicular to the upper surface of the phosphor portion 24 and the direction of the fluorescence emitted from the upper surface of the phosphor portion 24 on which the second nanoantenna 25 is formed.

[0062] In the wavelength conversion device 100 of this embodiment, by forming the first nano-antenna group 22A below the phosphor portion 24 , the narrow-angle fluorescence emitted from the upper surface of the phosphor portion 24 can be increased.

[0063] Here, refer to Figure 3 A specific relationship between the diffraction angle θ1 and the incident angle θ2 of the fluorescent light is described. In the following description, a diffraction angle of 30 degrees or less, which is an emission angle of narrow-angle light used as a calculation standard of light extraction efficiency, is defined as a narrow-angle range.

[0064] Figure 3 is a graph showing a result of analyzing the diffraction angle of the fluorescent light emitted upward from the second nano-antenna 25 with respect to the incident angle of the fluorescent light incident on the upper surface of the phosphor portion 24 using a rigorous coupled wave analysis (RCWA) method.

[0065] exist Figure 3 , the analysis was performed using a model in which the second nanoantennas 25 made of Al having a height of 150 nm, a diameter of 200 nm, and a second pitch P2 of 350 nm were arranged in a square grid pattern on the upper surface of the phosphor portion 24. The fluorescence incident on the upper surface of the phosphor portion 24 from the inside of the phosphor portion 24 was linearly polarized with a wavelength of 550 nm.

[0066] exist Figure 3 In the figure, the diffraction angle relative to the incident angle of the fluorescence when the fluorescence emitted from the upper surface of the phosphor portion 24 on which the second nanoantenna 25 is formed exhibits zero-order diffraction is indicated by a solid line, and the diffraction angle relative to the incident angle of the fluorescence when the fluorescence exhibits first-order diffraction is indicated by a dashed line.

[0067] exist Figure 3 In FIG. 1 , the narrow angle range is indicated by a dotted line. Figure 3 , when fluorescence is emitted at a narrow angle from the upper surface of the phosphor portion 24 on which the second nanoantenna 25 is formed, the condition of the incident angle of the fluorescence (hereinafter also referred to as the narrow angle condition) is 0 degrees to 17 degrees or 37 degrees to 89 degrees.

[0068] like Figure 2 As shown, when the incident angle θ3 of the fluorescent light does not satisfy the narrow angle condition, that is, when the incident angle of the fluorescent light is 17 to 37 degrees, the fluorescent light is totally reflected by the upper surface of the phosphor portion 24 and returns to the inside of the phosphor portion 24 or is emitted at a diffraction angle θ4 greater than 30 degrees. For example, the fluorescent light returned to the inside of the phosphor portion 24 travels toward the lower surface of the phosphor portion 24 at the same emission angle as the incident angle (angle θ3), and is incident on the first nanoantenna 22 inside the second translucent portion 21.

[0069] In the wavelength conversion device 100 of the embodiment, the first nano-antennas 22 are arranged at an arrangement pitch (first pitch P1) such that each of the first nano-antennas 22 changes the angle of the fluorescence traveling from the phosphor portion 24 and returns the fluorescence to the inside of the phosphor portion 24, and at this time, a large amount of fluorescence having an angle satisfying the narrow angle condition is generated. When the fluorescence returned to the inside of the phosphor portion 24 reaches the first nano-antenna 22 at an angle θ3 that does not satisfy the narrow angle condition, the fluorescence can be diffracted by the first nano-antenna 22 into fluorescence at an angle θ2 that satisfies the narrow angle condition.

[0070] A fluorescence component that does not satisfy the narrow angle condition among the fluorescence that is excited by the excitation light inside the phosphor portion 24 and directly travels to the second translucent portion 21 may be similarly diffracted by the first nanoantenna 22 into fluorescence having an angle θ2 that satisfies the narrow angle condition.

[0071] Therefore, the fluorescence diffracted by the first nanoantenna 22 and reaching the upper surface of the phosphor portion 24 is extracted by the second nanoantenna 25 as narrow-angle fluorescence (fluorescence having a diffraction angle θ1) at a higher ratio because a large amount of fluorescence satisfying the above narrow-angle condition has been generated.

[0072] Therefore, since the wavelength conversion device 100 of this embodiment allows an increase in the proportion of fluorescence extracted at a narrow angle by the second nanoantenna 25 , the light extraction efficiency of the wavelength conversion device 100 can be improved.

[0073] Figure 4 is shown to be used in conjunction with the RCWA method Figure 3 A graph showing the results of analyzing the percentage of the intensity of the fluorescence emitted from the upper surface of the phosphor portion 24 on which the second nano-antenna 25 is formed relative to the incident angle of the fluorescence is shown in FIG. Figure 4 , the dotted arrow indicates the range of the incident angle of fluorescence when the fluorescence is extracted from the second nano-antenna 25 at a narrow angle (having a diffraction angle of 30 degrees or less).

[0074] according to Figure 4 , when the incident angle of the fluorescence is 0 to 17 degrees, the intensity percentage of the fluorescence at the zero-order diffraction is about 7% to 20%, and when the incident angle of the fluorescence is 37 to 89 degrees, the intensity percentage of the fluorescence at the first-order diffraction is about 1% to 12%. When the incident angle of the fluorescence does not meet the narrow angle condition (when the diffraction angle is 17 to 37 degrees), the maximum intensity percentage of the fluorescence is about 13%.

[0075] In the wavelength conversion device 100 of this embodiment, each of the first nano-antenna 22 and the second nano-antenna 25 has a conical shape that narrows upward, such as Figure 1 and Figure 2shown.

[0076] According to this embodiment, the second nanoantenna 25 having a conical shape increases the ratio of fluorescence emitted from the upper surface of the phosphor portion 24 on which the second nanoantenna 25 is formed when fluorescence is incident from the bottom surface side of the second nanoantenna 25 having a large cross-sectional area.

[0077] According to the embodiment, the first nano-antenna 22 having a conical shape increases the ratio of fluorescence reflected by the first nano-antenna 22 when fluorescence is incident from the vertex side of the first nano-antenna 22 having a small cross-sectional area.

[0078] Therefore, according to this embodiment, since the proportion of fluorescence reflected toward the second nanoantenna 25 can be increased at the first nanoantenna 22, and the proportion of fluorescence emitted from the upper surface of the phosphor portion 24 can be increased at the second nanoantenna 25, the light extraction efficiency of the wavelength conversion device 100 can be improved.

[0079] [Method of Forming the First Nanoantenna and the Second Nanoantenna]

[0080] A method for forming the first nano-antenna 22 and the second nano-antenna 25 in the wavelength conversion device 100 of this embodiment is described below.

[0081] First, the first nano-antenna 22 as the first nano-antenna group is formed on the upper surface of the flat plate-shaped first translucent portion 19 (step 1). When the supporting substrate 15 of the light-emitting element 13 also serves as the first translucent portion 19, the light-emitting element 13 is mounted on the upper surface of the mounting substrate 12, and then the first nano-antenna 22 is formed on the upper surface of the supporting substrate 15.

[0082] Specifically, first, a metal film of Al or Ag, which is a base material of the first nanoantenna 22, is formed on the upper surface of the first semitransparent portion 19 by electron beam evaporation or sputtering film formation. Then, a resist is applied to the formed metal film, and patterning is performed in a square grid pattern using a nanoimprint device or an ion beam drawing device. Then, dry etching is performed using the resist as an etching mask, and then the resist is removed, thereby forming the first nanoantenna 22.

[0083] Next, a semi-transparent main body portion 23 is formed on the upper surface of the first semi-transparent portion 19 to cover the upper surface of the first semi-transparent portion 19, while filling the semi-transparent main body portion 23 between the corresponding first nanoantennas 22 (step 2). Specifically, a SiO2 film is formed by electron beam evaporation or sputtering film formation to form the semi-transparent main body portion 23.

[0084] Next, the upper surface of the semi-transparent body part 23 is surface polished by mechanical polishing and CMP (chemical mechanical polishing) to smooth the upper surface (step 3). Thus, the flat plate-shaped second semi-transparent part 21 including the first nanoantenna 22 and the semi-transparent body part 23 is formed.

[0085] Next, the phosphor portion 24 is bonded to the upper surface of the second translucent portion 21 (step 4). For example, surface polishing is performed on the lower surface of the phosphor portion 24 by a mechanical polishing process and a CMP process thereafter, so that the lower surface is smoothed. Then, the upper surface of the second translucent portion 21 is bonded to the lower surface of the phosphor portion 24 by plasma activated bonding, thereby allowing the second translucent portion 21 to be directly bonded to the phosphor portion 24. The bonding method is not limited to direct bonding, and for example, bonding can be performed by placing the phosphor portion 24 on the upper surface of the second translucent portion 21 via a transparent resin and then hardening the transparent resin.

[0086] Finally, the second nano-antenna 25 as the second nano-antenna group is formed on the upper surface of the phosphor portion 24 (step 5). Specifically, similar to the method for forming the first nano-antenna 22, a metal film is formed on the upper surface of the phosphor portion 24, patterning is performed thereafter, and then etching is performed, thereby forming the second nano-antenna 25.

[0087] Through the process of step 1 to step 5, the first nano-antenna 22 and the second nano-antenna 25 of the wavelength conversion device 100 can be formed.

[0088] [verify]

[0089] Refer to the following Figures 5 to 7 The verification performed on the wavelength conversion device 100 of the present invention and the verification result thereof are described.

[0090] First, refer to Figure 5 Described is a verification result of the reflection intensity of the fluorescence when the first pitch P1 of the first nano-antenna 22 is changed.

[0091] Figure 5 is a graph showing the analysis result of the reflection intensity of the fluorescence with respect to the first pitch P1 when the angle of the fluorescence reflected by the first nano-antenna 22 satisfies the above-mentioned narrow angle condition using the RCWA method.

[0092] exist Figure 5 , the analysis was performed using a model in which the first nanoantennas 22 made of Al with a height of 150 nm and a diameter of 200 nm were arranged in a square grid pattern on the upper surface of the first semitransparent portion 19.

[0093] exist Figure 5, the analysis was performed using a model in which the second nanoantennas 25 made of Al having a height of 150 nm, a diameter of 200 nm, and a second pitch P2 of 350 nm were arranged in a square grid pattern on the upper surface of the phosphor portion 24.

[0094] exist Figure 5 In the embodiment, the first translucent portion 19 is made of sapphire, and the translucent main body portion 23 is made of SiO2. The light incident on the first nano-antenna 22 is linearly polarized with a wavelength of 550 nm. Figure 5 , it is assumed that the reflection intensity of the fluorescence reflected by the first nano-antenna 22 is 1 when the first pitch P1 is 350 nm.

[0095] according to Figure 5 When the first pitch P1 is smaller than the second pitch P2, the reflection intensity of the fluorescence of the first nano-antenna 22 increases. On the other hand, when the first pitch P1 is larger than the second pitch P2, the reflection intensity of the fluorescence of the first nano-antenna 22 decreases.

[0096] Thus, by setting the first pitch P1 to be equal to or smaller than the second pitch P2 (350 nm), the reflection intensity of the fluorescence satisfying the narrow angle condition can be increased by the first nano-antenna 22 .

[0097] Next, refer to Figure 6 and Figure 7 , describing verification results of the transmission intensity of fluorescence when the corresponding slopes of the first nanoantenna 22 and the second nanoantenna 25 are changed.

[0098] Figure 6 is a graph showing an analysis result of the transmission intensity of fluorescent light emitted from the upper surface of the phosphor portion 24 with respect to the tilt angle when the second nano-antenna 25 is provided with a slope narrowing upward from a columnar state, using the RCWA method.

[0099] exist Figure 6 In, use Figure 5 The verification is performed using a model similar to the one used in , with the only difference being that the slope of the second nanoantenna 25 is changed from 90 degrees (column state). Figure 6 In FIG. 1 , it is assumed that the transmission intensity is 1 when the slope of the second nanoantenna 25 is 90 degrees.

[0100] according to Figure 6 , as the tilt angle of the second nano-antenna 25 decreases, that is, as the second nano-antenna 25 approaches a conical shape from a columnar shape, the transmission intensity of the fluorescent light emitted from the upper surface of the phosphor portion 24 increases.

[0101] Figure 7: is a graph showing the analysis result of the reflection intensity of the fluorescent light reflected toward the inside of the phosphor part 24 with respect to the tilt angle when the first nano-antenna 22 is arranged with a slope narrowing upward from a columnar state using the RCWA method. Figure 7 In the example, the reflection intensity when the first nano-antenna 22 is 90 degrees is expressed as 1. The analytical model is similar to Figure 6 Analytical model in verification.

[0102] according to Figure 7 , as the tilt angle of the first nano-antenna 22 decreases, that is, as the first nano-antenna 22 approaches a conical shape from a columnar shape, the reflection intensity of the fluorescent light reflected toward the inside of the phosphor portion 24 increases.

[0103] according to Figure 6 and Figure 7 As shown in the results, according to the wavelength conversion device 100 of the present embodiment, by providing a slope to the first nanoantenna 22 and the second nanoantenna 25 to narrow upward, the reflection intensity of the fluorescence in the case of the first nanoantenna 22 and the transmission intensity of the fluorescence in the case of the second nanoantenna 25 can each be increased.

[0104] Second embodiment

[0105] Next, refer to Figure 8 and Fig. 9 A second embodiment is described. Figure 8 is a cross-sectional view schematically showing the configuration of a lighting device 200 according to the second embodiment. Fig. 9 is a cross-sectional view of the wavelength conversion device 210. Figure 8 In the example above, shadows are omitted for visibility reasons.

[0106] The housing 31 is a box-shaped housing having openings OP1 and OP2 respectively disposed on two surfaces facing each other. The housing 31 is provided with a support structure 31A for supporting an object at a position between the openings OP1 and OP2. The support structure 31A is provided with a through hole 31AO penetrating the support structure 31A at its center.

[0107] The light source 32 is a light source that is fixed in the opening OP1 and emits light L1 having a predetermined wavelength toward the opening OP2. The opening OP1, the through hole 31AO, and the opening OP2 are formed on the optical axis OA.

[0108] In this embodiment, the light source 32 is a laser light source having a light emitting layer made of an InGaN-based semiconductor. The light source 32 emits blue light having a peak wavelength of about 450 nm as the light L1.

[0109] The wavelength conversion device 210 is supported by a support structure 31A located on the optical axis OA. Specifically, the wavelength conversion device 210 is disposed on the upper surface of the support structure 31A in such a manner that the central portion of the bottom surface through which the optical axis OA passes is exposed from the through hole 31AO of the support structure 31A. In other words, in the wavelength conversion device 210, an area other than the center of the bottom surface of the wavelength conversion device 210 is supported by the support structure 31A.

[0110] like Fig. 9 As shown, the wavelength conversion device 210 includes Figure 2 Shown are the first translucent portion 19, the second translucent portion 21, the phosphor portion 24, the second nano-antenna 25, and the light reflecting member 26. In other words, the wavelength conversion device 210 has a configuration in which the mounting substrate 12 and the light emitting element 13 are removed from the configuration of the wavelength conversion device 100 in the first embodiment.

[0111] The wavelength conversion device 210 emits the excitation light (blue light) that has passed through the phosphor portion 24 without contributing to the generation of fluorescent light, and the fluorescent light (yellow light) emitted from the phosphor of the phosphor portion 24 . Figure 8 The excitation light and the fluorescent light emitted from the wavelength conversion device 210 are shown together as the light L2.

[0112] In the wavelength conversion device 210, the first nano-antenna 22 is formed only in a region of a portion of the upper surface of the first semi-transparent portion 19. Specifically, Fig. 9 As shown, the first nano-antenna 22 is formed in an area other than the incident area of ​​the light L1 emitted from the light source 32 in the upper surface of the first translucent portion 19. In other words, the first nano-antenna 22 is not formed in an area of ​​the upper surface of the first translucent portion 19 where the light L1 is directly incident.

[0113] This formation aspect of the first nano-antenna 22 allows light L1, which is excitation light emitted from the light source 32, to be suppressed from being reflected by the first nano-antenna 22 before being incident on the phosphor portion 24. This allows the ratio of excitation light incident on the phosphor portion 24 to be increased, and allows a greater amount of fluorescent light to be generated inside the phosphor portion 24.

[0114] The wavelength conversion device 210 may include a lens that collects laser light between the light source 32 and the wavelength conversion device 210 on the incident plane side of the light L1. Collecting laser light through the lens allows the wavelength conversion device 210 to be efficiently irradiated with laser light and reduces the area of ​​direct incidence of the light L1 in the upper surface of the first translucent portion 19, and therefore, the area in which the first nanoantenna 22 is formed can be expanded, and the proportion of fluorescence reflected by the first nanoantenna 22 can be increased.

[0115] The lens 33 is an optical member fixed in the opening OP2. That is, the lens 33 is located on the optical axis OA. The lens 33 is an optical lens that receives the light L2 emitted from the wavelength conversion device 210 and forms the light L2 in a desired light distribution to generate light L3 as illumination light. For example, a spherical lens and an aspherical lens can be used for the lens 33. The light L3 generated by the lens 33 is extracted to the outside of the housing 31.

[0116] The lighting device 200 having the above configuration can also provide effects similar to those of the first embodiment. That is, since the proportion of fluorescence extracted at a narrow angle by the second nano-antenna 25 can be increased, the light extraction efficiency of the lighting device 200 can be improved.

[0117] Third embodiment

[0118] Next, refer to Fig.10 and Fig.11 A third embodiment is described. Fig.10 is a cross-sectional view schematically showing the configuration of a lighting device 300 according to the third embodiment. Fig.11 is a cross-sectional view of the wavelength conversion device 310. Fig.10 In the figure, shadows are omitted in consideration of visibility. Only the differences from the first and second embodiments are described below.

[0119] The housing 31 is a box-shaped housing having an opening OP1 on one of two surfaces facing each other. The housing 31 has an opening OP2 on one of two surfaces facing each other in a direction perpendicular to the direction in which the two surfaces face each other. The housing 31 is provided with a support structure 31A facing the opening OP2 and supporting an object.

[0120] Similar to the second embodiment, the light source 32 is fixed in the opening OP1, and the lens 33 is fixed in the opening OP2. In this embodiment, the wavelength conversion device 310 is provided on the upper surface of the support structure 31A so that the optical axis OA of the light L1 emitted from the light source 32 is perpendicular to one side surface of the wavelength conversion device 310. That is, in this embodiment, the light L1 emitted from the light source 32 is incident on the side surface of the wavelength conversion device 310.

[0121] like Fig.11 As shown, the wavelength conversion device 310 includes Figure 2 Shown are the first translucent portion 19, the second translucent portion 21, the phosphor portion 24, the second nano-antenna 25, and the light reflecting member 26. In other words, the wavelength conversion device 310 has a configuration in which the mounting substrate 12 and the light emitting element 13 are removed from the configuration of the wavelength conversion device 100 in the first embodiment.

[0122] In the wavelength conversion device 310, the light reflecting member 26 is continuously formed from the lower end of the side surface of the first translucent portion 19 to the upper end of the side surface of the phosphor portion 24, except for a portion of the outer surface on which the light L1 emitted from the light source 32 is incident. In other words, a portion of the outer surface of the wavelength conversion device 310 on which the light L1 emitted from the light source 32 is incident is exposed from the light reflecting member 26.

[0123] According to the lighting device 300 of the present embodiment, the light L1 as the excitation light emitted from the light source 32 is directly incident from the side surface of the phosphor portion 24 exposed to the light reflecting member 26. Therefore, for example, when the light L1 emitted from the light source 32 is incident from the lower side of the wavelength conversion device 310, reflection of the light L1 by the first nanoantenna 22 can be suppressed.

[0124] Furthermore, according to the lighting device 300 of the present embodiment, since the light reflecting member 26 is formed on the side surface of the wavelength conversion device 310 except for one side surface on which the light L1 is incident, emission of the light L1 from the other side surface can be suppressed.

[0125] The lighting device 300 having the above configuration can also provide effects similar to those of the first embodiment. That is, since the proportion of fluorescence extracted by the second nano-antenna 25 at a narrow angle can be increased, the light extraction efficiency of the lighting device 300 can be improved.

[0126] Although the case where the phosphor portion 24 is a phosphor plate made of a single crystal YAG:Ce phosphor is described in the above embodiment, the configuration of the phosphor portion 24 is not limited thereto, and the phosphor portion 24 only needs to have a configuration in which light scattering is less likely to occur inside. For example, a plate having a resin or glass medium containing phosphor particles emitting yellow fluorescence may be used.

[0127] Although the above embodiment describes the case where the first nano-antenna 22 and the second nano-antenna 25 are arranged in a square grid pattern, the arrangement aspect is not limited thereto. For example, the first nano-antenna 22 and the second nano-antenna 25 may be arranged in a triangular grid pattern.

[0128] Although the case where the first nanoantenna 22 has a conical shape is described in the above embodiment, it is not limited thereto, and the first nanoantenna 22 only needs to have a shape that allows the fluorescence to be reflected toward the second nanoantenna 25. For example, the first nanoantenna 22 may have other conical shapes such as a quadrangular pyramid (or a cone) or a truncated cone shape such as a circular truncated cone shape.

[0129] Although the case where the second nano-antenna 25 has a conical shape is described in the above embodiment, it is not limited thereto, and the second nano-antenna 25 only needs to have a shape that allows emission of fluorescence at a narrow angle. For example, the second nano-antenna 25 may have other conical shapes such as a quadrangular pyramid (or a cone) or a truncated cone shape such as a circular truncated cone shape.

[0130] Although the case where the wavelength conversion device includes the light reflecting member 26 is described in the above embodiment, an optical multilayer reflective film or a metal reflective film may be used instead of the light reflecting member 26 or a combination thereof may be provided according to a desired light distribution.

[0131] Description of Reference Numerals

[0132] 100, 210, 310: Wavelength conversion device

[0133] 200, 300: Lighting device

[0134] 12: Install the base plate

[0135] 13: Light-emitting element

[0136] 14: Semiconductor structure layer

[0137] 15: Support substrate

[0138] 16: p electrode

[0139] 17: n electrode

[0140] 19: First translucent part

[0141] 21: Second translucent part

[0142] 22: The first nanoantenna

[0143] 23: Translucent main part

[0144] 24: Phosphor section

[0145] 25: Second nanoantenna

[0146] 26: Light reflecting member

[0147] 31: Shell

[0148] 32: Light source (laser light source)

[0149] 33: Lens

Claims

1. A wavelength conversion device, comprising: a flat-plate-shaped phosphor portion including a phosphor to be excited by excitation light to emit fluorescent light; a first nano-antenna group, the first nano-antenna group being disposed on a lower surface side of the phosphor portion and comprising a plurality of first nano-antennas, the respective plurality of first nano-antennas being made of metal arranged at a first pitch; a translucent body portion, the translucent body portion filling between adjacent first nanoantennas, formed on a lower surface of the phosphor portion to cover the lower surface of the phosphor portion, and made of a translucent material; as well as A second nano-antenna group, the second nano-antenna group is arranged on the upper surface of the phosphor portion and includes a plurality of second nano-antennas, and the corresponding plurality of second nano-antennas are made of metal arranged at a second pitch on the upper surface of the phosphor portion.

2. The wavelength conversion device according to claim 1, wherein: The first interval is equal to or smaller than the second interval.

3. The wavelength conversion device according to claim 1 or 2, wherein: The first nano-antenna has a cone shape or a truncated cone shape that is narrowed upward.

4. The wavelength conversion device according to claim 1 or 2, wherein: The second nano-antenna has a cone shape or a truncated cone shape that is narrowed upward.

5. The wavelength conversion device according to claim 1 or 2, wherein: The first nano-antenna is arranged at an upper surface of a translucent portion made of a translucent material, and The translucent body portion is formed on the translucent portion to cover an upper surface of the translucent portion.

6. The wavelength conversion device according to claim 5, wherein: The first nano-antenna is formed only in one region of the upper surface of the semi-transparent portion.

7. The wavelength conversion device according to claim 5, comprising: A light reflecting member is formed at a portion of a side surface of the wavelength conversion device and is continuously formed from a lower end of the side surface of the translucent body part to an upper end of the side surface of the phosphor part.

8. The wavelength conversion device according to claim 1 or 2, wherein: The phosphor portion has a characteristic of being excited by the excitation light to emit fluorescence having a peak wavelength of 520 nm to 570 nm, and The first nanoantenna has the first pitch of 500 nm or less.

9. The wavelength conversion device according to claim 8, wherein: The phosphor portion is made of yttrium aluminum garnet activated with cerium.

10. The wavelength conversion device according to claim 1 or 2, wherein: The phosphor portion includes a single crystalline phosphor.

11. The wavelength conversion device according to claim 1 or 2, wherein: The first nano-antenna and the second nano-antenna are arranged in a square grid pattern or a triangle grid pattern.

12. The wavelength conversion device according to claim 1 or 2, wherein: The first nanoantenna and the second nanoantenna are made of Al or Ag.

13. A lighting device, comprising: The wavelength conversion device according to claim 1; as well as A light source emits the excitation light toward the phosphor portion.

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