Wavelength conversion member and lighting device using same

Abstract

The purpose of the present invention is to provide: a wavelength conversion member with which a lighting device having a narrow-angle light distribution, high output, and low color unevenness can be configured; and a lighting device using the same.　This wavelength conversion member is characterized by comprising a flat plate-shaped phosphor member including a phosphor that is excited by excitation light to emit fluorescence, a reflection member that is provided on a side surface of the phosphor member and reflects the excitation light and the fluorescence, and a plurality of nanoantennas that are provided on one main surface of the phosphor member and comprise a metallic material or a dielectric material, wherein: the plurality of nanoantennas include a first nanoantenna group arranged in a lattice shape with a first arrangement period and a second nanoantenna group arranged in a lattice shape with a second arrangement period, the first arrangement period being a period corresponding to a first wavelength included in the wavelength range of the excitation light and the fluorescence, the second arrangement period being a period corresponding to a second wavelength included in the wavelength range of the excitation light and the fluorescence; in terms of the intensity ratio of light emitted in a predetermined angular range around a direction perpendicular to the main surface from a first region where the first nanoantenna group is formed in the phosphor member, light of the first wavelength is greater than light of the second wavelength; and in terms of the intensity ratio of light emitted in a predetermined angular range around a direction perpendicular to the main surface from a second region where the second nanoantenna group is formed in the phosphor member, light of the second wavelength is greater than light of the first wavelength.

Description

Wavelength conversion member and lighting device using the same

[0001] The present invention relates to a wavelength conversion member and an illumination device using the same.

[0002] A device has been proposed that performs wavelength conversion on light emitted from a light source to mix light of different colors, and uses a nano-sized antenna (hereinafter referred to as a nanoantenna) to distribute the light emitted from the light source at a narrow angle.

[0003] For example, Patent Document 1 discloses a wavelength conversion device having a configuration including a light source that emits blue light, a phosphor plate that is excited by the light emitted from the light source and emits fluorescence, an antenna array in which a plurality of nanoantennas are arranged at a predetermined interval on the light-emitting surface of the phosphor plate, and a light-reflecting film on the side surface of the phosphor plate. Examples of the light-reflecting film disclosed include a white paint film, an optical multilayer reflective film, and a metal reflective film.

[0004] JP 2018-13688 A

[0005] Consider an illumination device in which the wavelength conversion device described above is provided on the light-emitting surface of an LED. In this wavelength conversion device, providing a specularly reflective optical multilayer reflective film or a metal reflective film as a light-reflecting film on the side surface of the phosphor plate improves the narrow angle and light extraction efficiency compared to providing a diffusely reflective white paint film, but there is a problem in that color unevenness may occur.

[0006] The present invention has been made in consideration of the above-mentioned points, and aims to provide a wavelength conversion member that can be used to configure an illumination device with a narrow light angle, high output, and little color unevenness, and an illumination device using the same.

[0007] A wavelength conversion member according to the present invention includes a flat phosphor member containing a phosphor that is excited by excitation light to emit fluorescence, a reflecting member provided on a side surface of the phosphor member and reflecting the excitation light and the fluorescence, and a plurality of nanoantennas made of a metal material or a dielectric material provided on one main surface of the phosphor member, wherein the plurality of nanoantennas include a first group of nanoantennas arranged in a lattice pattern with a first arrangement period and a second group of nanoantennas arranged in a lattice pattern with a second arrangement period, and the first arrangement period is a period corresponding to a first wavelength included in the wavelength range of the excitation light and the fluorescence. the second arrangement period is a period corresponding to a second wavelength included in the wavelength range of the excitation light and the fluorescence, and the intensity ratio of light emitted from a first region in which the first nanoantenna group is formed in the phosphor material within a predetermined angular range centered on a direction perpendicular to the main surface is such that the light of the first wavelength is greater than the light of the second wavelength, and the intensity ratio of light emitted from a second region in which the second nanoantenna group is formed in the phosphor material within a predetermined angular range centered on a direction perpendicular to the main surface is such that the light of the second wavelength is greater than the light of the first wavelength.

[0008] 1 is a top view showing the configuration of a lighting device according to Example 1. FIG. 2 is a cross-sectional view showing the configuration of a lighting device according to Example 1. FIG. 3 is a diagram showing simulation results of calculating the proportion of light intensity within ±30° for a lighting device according to a comparative example of Example 1 for each period of the nanoantenna when the side surfaces are made of a diffuse reflection film. FIG. 4 is a diagram showing simulation results of calculating the proportion of light intensity within ±30° for a lighting device according to a comparative example of Example 1 for each period of the nanoantenna when the side surfaces are made of a specular reflection film. FIG. 5 is a diagram showing simulation results of the proportion of light intensity within ±30° for a lighting device according to a comparative example of Example 1 for each period of the nanoantenna when the side surfaces are made of a diffuse reflection film. FIG. 6 is a diagram showing simulation results of the light distribution pattern of a lighting device according to a comparative example of Example 1. FIG. 7 is a diagram showing simulation results of the light distribution pattern of a lighting device according to a comparative example of Example 1. Fig. 1 is a diagram showing the relationship between the regular reflectance at a side surface of a phosphor member of an illumination device according to a comparative example of Example 1 and the light extraction efficiency of the illumination device. Fig. 2 is a top view showing the configuration of an illumination device according to Example 2. Fig. 3 is a top view showing the configuration of an illumination device according to Modification 1 of Example 2. Fig. 4 is a top view showing the configuration of an illumination device according to Modification 2 of Example 2.

[0009] In the following, preferred embodiments of the present invention will be described, but these may be modified and combined as appropriate. In the following description and accompanying drawings, substantially the same or equivalent parts are designated by the same reference numerals.

[0010] The configuration of an illumination device 100 according to a first embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a top view showing the configuration of the illumination device 100 according to the first embodiment. Figure 2 is a cross-sectional view of the illumination device 100 taken along line 2-2 in Figure 1.

[0011] The lighting device 100 includes a mounting substrate 11, a light-emitting element 13 flip-chip mounted on the mounting substrate 11, and a wavelength conversion member 15 provided on the light-emitting element 13. The wavelength conversion member 15 is a member including a phosphor member 35 that is excited by light emitted from the light-emitting element 13 and emits fluorescence.

[0012] As shown in FIG. 1 , the mounting substrate 11 is a flat substrate with a rectangular top surface. The mounting substrate 11 is made of an insulating material. Preferably, the mounting substrate 11 has high heat dissipation properties. In this embodiment, the mounting substrate 11 is made of aluminum nitride (AlN) ceramic, which is insulating and has high heat dissipation properties. However, the mounting substrate 11 may also be made of another insulating material, such as alumina.

[0013] 2, a p-type wiring electrode 11A and an n-type wiring electrode 11B, which are metal electrodes spaced apart from each other, are formed on the upper surface of the mounting substrate 11. The p-type wiring electrode 11A and the n-type wiring electrode 11B are electrically connected to an external power supply (not shown).

[0014] The light-emitting element 13 is an LED element including a substrate 17, a semiconductor stack 25 consisting of a plurality of nitride-based semiconductor layers including an active layer formed on the underside of the substrate 17, a p-electrode 27, and an n-electrode 31.

[0015] The substrate 17 is a flat sapphire substrate having a rectangular upper surface. The substrate 17 is a growth substrate for the semiconductor layers that constitute the light-emitting element 13. As shown in FIG. 2 , the lower surface of the substrate 17 is the growth surface for the semiconductor layers. In addition, the wavelength conversion member 15 is provided on the upper surface of the substrate 17. The upper and lower surfaces of the substrate 17 are flat surfaces on which, for example, no intentional uneven structure is formed. In addition, the substrate 17 is translucent to light emitted from the active layer, and the light from the active layer passes through the substrate 17 and enters the wavelength conversion member 15.

[0016] The semiconductor stack 25 is a stacked structure including a plurality of semiconductor layers formed to cover the lower surface of the substrate 17. The semiconductor stack 25 includes an n-type semiconductor layer 19, an active layer 21, and a p-type semiconductor layer 23, which are epitaxially grown in this order on the substrate 17 by MOCVD.

[0017] The n-type semiconductor layer 19 as a first semiconductor layer is formed so as to cover the lower surface of the substrate 17, and is an n-type GaN layer doped with n-type impurities as a first conductivity type. The n-type semiconductor layer 19 is doped with, for example, Si as the n-type impurity.

[0018] The n-type semiconductor layer 19 has a mesa shape. Specifically, the n-type semiconductor layer 19 has a recessed region 1 (the right side in FIG. 2 ), which is a region along the outer edge of the lower surface to which the n-electrode 31 is connected, and the other regions other than the region 1 form a plateau. The region 1 has a surface 19E that is recessed further than the surfaces of the plateau portions of the other regions.

[0019] The active layer 21 is formed on the mesa-shaped plateau portion on the lower surface of the n-type semiconductor layer 19. The wavelength of light emitted from the active layer depends on the material and composition of the semiconductor stack 25. In this embodiment, the active layer 21 is a semiconductor layer having a multi-quantum well (MQW) structure made up of InGaN well layers and GaN barrier layers. In this embodiment, the emission peak wavelength of the active layer 21 is within the range of 450±20 nm.

[0020] The p-type semiconductor layer 23 as the second semiconductor layer is formed across the lower surface of the active layer 21, and is a layer made up of a plurality of semiconductor layers including a p-type GaN layer doped with a p-type impurity as a second conductivity type. The p-type GaN layer of the p-type semiconductor layer 23 is doped with, for example, Mg as the p-type impurity.

[0021] The p-type semiconductor layer 23 is configured by stacking, for example, an electron blocking layer made of an AlGaN layer, a p-type cladding layer made of a p-type GaN layer, and a contact layer made of a p-type GaN layer doped with Mg at a higher concentration than the p-type cladding layer, in this order on the lower surface of the active layer 21.

[0022] The p-electrode 27 is a metal electrode formed across the lower surface of the p-type semiconductor layer 23. The p-electrode 27 is electrically connected to the p-type semiconductor layer 23. The p-electrode 27 is electrically connected to the p-wiring electrode 11A on the mounting substrate 11 by an AnSu eutectic via a conductive p-type electrode pad 29.

[0023] Furthermore, it is preferable that the p-electrode 27 has a property of reflecting light emitted from the active layer 21. It is preferable that the p-electrode 27 is made of a metal with high reflectivity, such as aluminum (Al) or silver (Ag), or an alloy thereof. The p-type electrode pad 29 is made of a metal film in which, for example, Ti, Pt, and Au are stacked in this order on the p-electrode 27.

[0024] The n-electrode 31 is a metal electrode provided on the exposed surface 19E of the n-type semiconductor layer 19. The n-electrode 31 is electrically connected to the n-type semiconductor layer 19. The n-electrode 31 is also electrically connected to the n-wiring electrode 11B on the mounting substrate 11 by an AnSu eutectic via a conductive n-type electrode pad 33. The n-type electrode pad 33 is made of a metal film in which, for example, Ti, Pt, and Au are laminated in this order on the n-electrode 31.

[0025] As described above, the light emitting element 13 is flip-chip mounted on the mounting substrate 11, and the upper surface of the substrate 17 serves as the light emitting surface of the light emitting element 13. While the light emitting element 13 has been described as having a mesa shape, the present invention is not limited to this, and the n-type semiconductor layer 19 and the n-wiring electrode 11B may be electrically connected to each other via a through hole that is provided in the semiconductor laminate 25 and extends from the p-type semiconductor layer 23 to the n-type semiconductor layer 19.

[0026] The wavelength conversion member 15 is configured to include a phosphor member 35, a plurality of nanoantennas 37A to 37C provided on an upper surface 35S of the phosphor member 35, and a reflecting member 39 provided on a side surface of the phosphor member 35.

[0027] The phosphor member 35 is a flat plate-shaped member having a rectangular upper surface. The phosphor member 35 contains a phosphor that emits fluorescence when excited by the light emitted from the active layer 21. In this embodiment, the phosphor member 35 is a ceramic phosphor plate made of a single layer of yttrium aluminum garnet (YAG:Ce) with cerium as the luminescence center. The phosphor member 35 is bonded to the substrate 17 of the light-emitting element 13. The surface of the phosphor member 35 that is bonded to the light-emitting element 13, i.e., the lower surface of the phosphor member 35 in FIG. 2, is a flat surface.

[0028] The phosphor member 35 may be, for example, a plate having a thin film containing a phosphor formed on the surface of a transparent support, or may be a resin or glass layer containing phosphor particles such as YAG:Ce phosphor.

[0029] The above-described phosphor is excited by blue light with a wavelength of approximately 450 nm and emits yellow fluorescence with a wavelength of approximately 480 to 750 nm. Therefore, in this embodiment, when blue light with a peak wavelength of 450±20 nm emitted from the active layer 21 is introduced into the phosphor member 35, a portion of the blue light is wavelength-converted to yellow fluorescence. The remaining blue light passes through the phosphor member 35 without being wavelength-converted. Therefore, the blue light that has passed through the phosphor member 35 and the yellow fluorescence from the phosphor contained in the phosphor member 35 are emitted from the upper surface 35S of the phosphor member 35.

[0030] White light is extracted from the lighting device 100 by mixing the blue light and yellow fluorescent light emitted from the upper surface 33S of the phosphor member 35. In order to achieve stable white light, the phosphor member 35 preferably has a thickness within a range of 40 to 200 μm. In this embodiment, the thickness of the phosphor member 35 is 100 μm.

[0031] [Nanoantenna] The nanoantenna 37A, the nanoantenna 37B, and the nanoantenna 37C (hereinafter, these are also collectively referred to as nanoantennas 37A to 37C) are TiO ２ It is a cylindrical structure consisting of

[0032] 1, in a top view, that is, in a plan view seen from a direction perpendicular to the top surface 35S of the phosphor member 35, the phosphor member 35 has, on the top surface 35S, strip-shaped regions AR1 to AR3 that are aligned along one side of the phosphor member 35. The region AR1 is a region in which a plurality of nanoantennas 37A are arranged, the region AR2 is a region in which a plurality of nanoantennas 37B are arranged, and the region AR3 is a region in which a plurality of nanoantennas 37C are arranged.

[0033] The arrangement period of the nanoantennas 37A in region AR1, the arrangement period of the nanoantennas 37B in region AR2, and the arrangement period of the nanoantennas 37C in region AR3 are all different. The multiple nanoantennas 37A to 37C are arranged in a lattice-like arrangement pattern at a constant interval in each of regions AR1 to AR3 on the upper surface 35S of the phosphor member 35. In other words, the multiple nanoantennas 37A to 37C are arranged in a constant arrangement pattern at a constant interval in each of regions AR1 to AR3 in a top view to form an antenna array. In this embodiment, the multiple nanoantennas 37A to 37C are arranged so as to form a triangular lattice.

[0034] Specifically, the first region, AR1, is a region in which multiple nanoantennas 37A are arranged at an array period L1. The second region, AR2, is a region in which multiple nanoantennas 37B are arranged at an array period L2 that is larger than the array period L1. The third region, AR3, is a region in which multiple nanoantennas 37C are arranged at an array period L3 that is larger than the array period L2. That is, the array periods L1 to L3 are different from one another, with the array period L1 being the smallest and the array period L3 being the largest (L1<L2<L3). In this embodiment, the array period L1 is 360 nm, the array period L2 is 440 nm, and the array period L3 is 500 nm.

[0035] In other words, a first nanoantenna group is formed in the first region, in which a plurality of nanoantennas 37A are arranged in a lattice pattern with an arrangement period L1 as a first arrangement period. A second nanoantenna group is formed in the second region, in which a plurality of nanoantennas 37B are arranged in a lattice pattern with an arrangement period L2 as a second arrangement period. A third nanoantenna group is formed in the region AR3, in which a plurality of nanoantennas 37C are arranged in a lattice pattern with an arrangement period L3 as a third arrangement period.

[0036] In this example, the diameter of each of the plurality of cylindrical nanoantennas 37A to 37C in top view is 80% of the arrangement period, i.e., the diameter of nanoantenna 37A is 288 nm, the diameter of nanoantenna 37B is 352 nm, and the diameter of nanoantenna 37C is 400 nm.

[0037] 2, the height H of each of the multiple nanoantennas 37A to 37C is common to all of the nanoantennas 37A to 37C and is, for example, 100 nm to 400 nm. If the height is too low, scattering at the nanoantenna will be reduced, resulting in a low intensity of the extracted emitted light. Furthermore, if the aspect ratio (height / diameter) is too large, manufacturing will be difficult. In this embodiment, the height H is set to 300 nm and 350 nm. This dimension is set to an aspect ratio that takes into account ease of manufacturing and durability in practical use.

[0038] The shape of the nanoantennas 37A to 37C can be a columnar or pyramidal shape, and other shapes such as a prismatic shape, a conical shape, or a pyramidal shape can be used in addition to a cylindrical shape. In this case, it is preferable that the maximum width of the nanoantennas 37A to 37C in a top view is 75% to 85% of the arrangement period from the viewpoint of narrow angle performance and increasing the intensity of the emitted light. Furthermore, the nanoantennas 37A to 37C are made of TiO ２ In addition, Al ２ O ３ , Nb ２ O ５ , HfO ２ , ZrO ２ , Ta ２ O ５ , CeO ２ , La ２ O ３ , AlN, GaN, Si ３ N ４ Alternatively, the insulating layer 11 may be formed of a dielectric material such as a metal oxide, a metal nitride, or a metal carbide, such as SiC, or a metal material such as Al, Au, Ag, or Ni.

[0039] [Reflective Member] As shown in FIG. 2 , the reflective member 39 is provided on the side surface 35E of the phosphor member 35. The reflective member 39 is composed of a dielectric multilayer film 41 formed on the side surface of the phosphor member 35 and a metal film 43 formed on the dielectric multilayer film 41. The reflective member 39 has the function of reflecting light that reaches the side surface of the phosphor member 35. The reflective member 39 preferably increases the specular reflectance of the reflected light that reaches the side surface of the phosphor member 35, and the specular reflectance of the reflected light is preferably 80% or more. The side surface 35E of the phosphor member 35 is preferably smoothed to increase the specular reflectance of the reflective member 39. In this embodiment, the reflective member 39 is also provided on the side surface of the light-emitting element 13, covering the side surface of the light-emitting element 13.

[0040] The dielectric multilayer film 41 is a dielectric multilayer film reflector formed by stacking multiple dielectric films with different refractive indices, and is configured to reflect light within a predetermined wavelength range that is incident at a predetermined angle range.

[0041] Examples of dielectric materials with low refractive index include silicon oxide (SiO ２ ), alumina (Al ２ O ３ ) is used as a high refractive index dielectric material. ２ ), zirconia (ZrO ２ ), niobium pentoxide (Nb ２ O ５ ), lanthanum oxide (La ２ O ３ ), tantalum oxide (Ta ２ O ５ ), hafnium oxide (HfO ２ In this embodiment, the dielectric multilayer film 41 is preferably made of a material that has low light absorption, such as a silicon oxide film (SiO ２ ) and niobium pentoxide (Nb ２ O ５ ) are alternately stacked in 39 layers.

[0042] In this embodiment, the reflection of light by the dielectric multilayer film 41 is a reflection at the interface between the low refractive index material and the high refractive index material, and is a regular reflection with the angle of incidence and the angle of reflection being equal.

[0043] The metal film 43 is a metal film formed on the surface of the dielectric multilayer film 41. The metal film 43 is made of a metal with high reflectivity, such as aluminum (Al) or silver (Ag). The metal film 43 reflects light that is outside a predetermined angle range or a predetermined wavelength range and has passed through the dielectric multilayer film 41 to reach the metal film 43. The reflection by the metal film 43 is a reflection on the metal surface, and is a specular reflection.

[0044] In this embodiment, by providing a reflecting member 39 that causes specular reflection on the side surface of the phosphor member 35, more light reaches the upper surface of the phosphor member 35 at an angle at which diffraction by the nanoantenna is likely to occur, i.e., more light is incident on the upper surface of the phosphor member 35 at an angle at which diffraction is likely to occur, compared to the case where a reflecting member that causes diffuse reflection is provided. The details of how providing a reflecting member 39 made of a specular reflection material increases the amount of light that is incident on the upper surface of the phosphor member 35 at an angle at which diffraction is likely to occur, i.e., at or above the critical angle, will be described later.

[0045] [Array pitch and function of nanoantennas] The array pitch and light diffraction function of nanoantennas 37A to 37C are described below. As described above, lighting device 100 is a device that provides white light by mixing blue light and yellow fluorescent light emitted from upper surface 33S of phosphor member 35.

[0046] If the nanoantennas 37A to 37C are not provided on the phosphor member 35, the white light is more likely to have color unevenness due to the difference in light distribution characteristics between the blue light passing through the phosphor member 35 and the yellow light emitted by the phosphor contained in the phosphor member 35. Specifically, the blue light passing through the phosphor member 35 and exiting from the upper surface 35S tends to have a narrower light distribution angle than the yellow light. On the other hand, because the fluorescence from the phosphor is emitted isotropically, the yellow fluorescence tends to have a Lambertian light distribution. Therefore, the white light emitted from the lighting device tends to be more bluish in the direction perpendicular to the upper surface than in other directions.

[0047] To address the color unevenness caused by the difference in light distribution between the blue light and the yellow fluorescent light, a nanoantenna with a light diffraction function is provided on the upper surface 35S of the phosphor member 35. In the lighting device 100, by diffracting the fluorescent light emitted from the upper surface 35S, the light distribution of the fluorescent light is narrowed in angle, bringing it closer to the light distribution of the blue light, thereby eliminating the color unevenness.

[0048] Here, the light angle narrowing effect of the nanoantenna will be explained. When light reaches the upper surface 35S of the phosphor member 35 at an angle equal to or greater than the critical angle, the light is totally reflected by the upper surface 35S of the phosphor member 35. When total reflection occurs, an evanescent wave is generated that seeps from the upper surface 35S of the phosphor member 35 toward the low refractive index medium. This evanescent wave propagates along the upper surface 35S, in other words, along the interface between the phosphor member 35 and air.

[0049] The evanescent waves propagating along the upper surface of the phosphor member 35 are scattered when they reach the nanoantennas and are emitted as visible light with the same wavelength as the fluorescence in a direction that conforms to the diffraction conditions determined by the arrangement period of the nanoantennas. This phenomenon causes the light to be emitted in a light distribution angle range (emission angle range) that conforms to the diffraction conditions, thereby promoting a narrowing of the angle of light emitted from the upper surface of the phosphor member 35. Narrowing the angle of fluorescence by the nanoantennas means, for example, that the action of the nanoantennas increases the amount of fluorescence emitted at a light distribution angle of within ±30°.

[0050] Note that light incident on the upper surface 35S of the phosphor member 35 at an angle less than the critical angle is less likely to be diffracted and is transmitted, so that it is less likely to have a narrow-angle light distribution. In other words, light incident on the upper surface 35S at an angle equal to or greater than the critical angle is more likely to be diffracted, and the greater the proportion of light that reaches the upper surface 35S at an angle equal to or greater than the critical angle, the more diffracted light there is.

[0051] The inventors of the present application have discovered that when the period of a nanoantenna having the above-described diffraction function is a single period, the light distribution, for example, the proportion of light intensity within 30 degrees, varies depending on the wavelength, but that this tendency becomes more pronounced when a reflective member 39 that specularly reflects light from within the phosphor member 35 is provided, as in this embodiment.

[0052] Therefore, in this embodiment, nanoantennas 37A to 37C are provided in regions AR1 to AR3, respectively, and are arranged at arrangement periods L1 to L3. The arrangement periods L1 to L3 of nanoantennas 37A to 37C correspond to the wavelengths included in the wavelength ranges of blue light and yellow fluorescence, respectively. Specifically, each of the arrangement periods L1 to L3 is an arrangement period that makes it easier for light of any wavelength included in the wavelength ranges of blue light and yellow fluorescence to be diffracted by the nanoantenna and narrowed in angle.

[0053] The inventors discovered that by setting the arrangement period of the nanoantennas in this way, deviations in the light distribution of light with different colors can be reduced, resulting in uniform white light with little color unevenness.

[0054] [Enhancement of Diffraction by Reflecting Member] The increase in light diffracted by the nanoantennas by the reflecting member 39 can be explained as follows: Of the light that propagates through the phosphor member 35 and reaches the upper surface 35S, the ratio of light that is extracted by transmission or diffraction by the nanoantennas to light that is reflected by the upper surface 35S is about 1:5, and most of the light is reflected by the upper surface 35S and returns into the phosphor member 35.

[0055] The light reflected by the upper surface 35S includes light that is totally reflected at the interface between the phosphor member 35 and air at the upper surface 35S and light that is reflected by the lower surface of the nanoantenna. The light reflected by the upper surface 35S is reflected by, for example, the side surface of the phosphor member 35, the rear surface of the phosphor member 35, the p-electrode 27 of the light-emitting element 13, etc., and then enters the upper surface 35S again.

[0056] As described above, when light is incident on the upper surface 35S at an angle equal to or greater than the critical angle and is totally reflected, diffraction by the nanoantennas is likely to occur. Therefore, if the incident angle when the light is reflected on the side surface of the phosphor member 35 and then incident on the upper surface 35S again is equal to or greater than the critical angle, diffraction is likely to occur.

[0057] For example, consider a case where a light-scattering resin member is provided on the side surface of the phosphor member 35 instead of the reflective member 39. The resin member may be, for example, a transparent resin containing light-scattering particles (e.g., titanium oxide (TiO ２Consider a resin member made of a so-called white resin in which phosphor particles (e.g., fluorine) are dispersed. Because the refractive index of the resin member is greater than that of air, the critical angle at the interface between the phosphor member 35 and the resin member is greater than the critical angle at the interface between the phosphor member 35 and the air. In this case, when light reflected from the top surface 35S reaches the side surface of the phosphor member 35, light below the critical angle is not totally reflected at the interface between the phosphor member 35 and the resin member but passes through the interface and is diffusely reflected by the scattering particles contained in the resin member. For example, light that was above the critical angle when it first entered the top surface 35S changes its angle of incidence to various angles when it re-enters the top surface 35S after diffuse reflection, resulting in less light incident above the critical angle. This reduces the amount of light diffracted, and the proportion of light extracted at narrow angles is reduced. Furthermore, light absorption occurs on the reflective surfaces, such as the side and back surfaces, of the phosphor member 35, reducing the light extraction efficiency.

[0058] In this embodiment, as described above, by using the reflecting member 39 to specularly reflect light off the side surface of the phosphor member 35, light that reaches a critical angle or greater when re-entering the nanoantenna can reach the top surface of the phosphor member 35 while maintaining that angle. Also, due to the nature of the dielectric multilayer film, there is almost no light absorption by the dielectric multilayer film 41. In this embodiment, since much light is diffracted and absorption is low, there is little loss due to diffuse reflection and absorption of light, and the efficiency of extracting narrow-angle light from the top surface 35S of the phosphor member 35 is higher than in a configuration in which the reflecting member 39 is not provided.

[0059] In this embodiment, the reflective member 39 is also provided on the side surface of the light-emitting element 13, but it is sufficient that the reflective member 39 is provided at least on the side surface of the phosphor member 35. In other words, to obtain the above-described effect, it is sufficient that the reflective member 39 is formed only on the side surface of the phosphor member 35. It is preferable that the reflective member 39 is also provided on the side surface of the light-emitting element 13, because this allows more light to be specularly reflected and more light to reach the upper surface of the phosphor member 35 at an angle at which it is easily diffracted.

[0060] In this embodiment, the regions where the multiple nanoantennas 37A to 37C are formed may be formed in any region of the upper surface 35S. For example, the regions AR1 to AR3 may be regions where the semiconductor stack 25 of the light-emitting element 13 is formed when viewed from above. In this embodiment, the regions AR1 to AR3 are formed over the entire upper surface of the phosphor member 35. In other words, nanoantennas are formed over the entire upper surface 35S of the phosphor member 35.

[0061] In this embodiment, if the area ratios of the areas AR1 to AR3 to the area of ​​the upper surface 35S of the phosphor member 35 are designated as area ratios S1 to S3, they are all the same ratio, i.e., S1=S2=S3=1 / 3.

[0062] 1 and 2 are merely schematic illustrations for explaining the nanoantennas 37A to 37C, and are not to the actual scale. The phosphor member 35 is, for example, 1 mm square, and in this case, more nanoantennas 37A to 37C are provided than those shown in FIGS.

[0063] [Nanoantenna Array Period] The following describes how to set the array periods L1 to L3 of the nanoantennas 37A to 37C. First, select the wavelength (also referred to as the target wavelength) to be controlled by the nanoantenna for light distribution control. In this example, to obtain white light by mixing blue light and yellow fluorescent light, the target wavelength was selected to be within the wavelength range of the mixed light of the blue light and yellow fluorescent light.

[0064] The peak wavelength of the emission spectrum of blue light emitted from the nitride-based blue light-emitting element used in the light-emitting element 13 is generally approximately 450 nm. However, taking into consideration that this may vary depending on the material and structure of the active layer, the wavelength range of the blue light is set to 430 nm or more and 470 nm or less (i.e., 450±20 nm) (first wavelength band). In this embodiment, the center wavelength of 450 nm of the first wavelength band is set as the target wavelength (first wavelength) for which light distribution control is performed by the nanoantenna for blue light. That is, the period of the nanoantenna 37A is set based on the results of analytically determining the period at which 450 nm light is most effectively diffracted. Specifically, the period of the nanoantenna 37A can be determined for various periods by analyzing the intensity of 450 nm light emitted via the nanoantenna 37 within ±30° of the direction perpendicular to the upper surface 35S of the phosphor member 35 using rigorous coupled wave analysis (RCWA), and set based on the obtained light intensity. As a result, light of 450 nm±20 nm is diffracted well, and the intensity of the light distributed in the direction ±30 degrees perpendicular to the upper surface 35S of the phosphor member 35 is increased.

[0065] The emission spectrum of yellow fluorescence from a phosphor made of YAG:Ce generally exhibits a broad peak near approximately 550 nm. The peak wavelength of the yellow fluorescence is, for example, 520 nm or more and 570 nm or less. The wavelength with the highest luminosity is 555 nm (green to yellow). Taking into account the peak wavelength of the yellow fluorescence and the wavelength with the highest luminosity, the wavelength range of the yellow light was set to 530 nm or more and 570 nm or less (550±20 nm) (second wavelength band) so that the center wavelength was close to the wavelength with the highest luminosity (second wavelength). In this example, the center wavelength of 550 nm of the second wavelength band was set as the target wavelength (second wavelength) for light distribution control of the yellow light by the nanoantenna.

[0066] That is, the period of the nanoantenna 37B was set based on the results of an analysis that determined the period that best diffracts 550 nm light. Specifically, the period of the nanoantenna 37B can be determined by analyzing the intensity of 550 nm light emitted via the nanoantenna 37 within ±30° in the direction perpendicular to the top surface 35S of the phosphor member 35 using the RCWA method for various periods, and then selected based on the obtained light intensity. This results in good diffraction of 550 nm ±20 nm light, increasing the intensity of the light distributed within ±30° in the direction perpendicular to the top surface 35S of the phosphor member 35. Note that while wavelengths around 550 nm are the boundary between yellow and green light, for simplicity of explanation, 550 ±20 nm is treated as the wavelength range of yellow light.

[0067] The second wavelength band can be changed depending on the type of phosphor used in the phosphor member 35, i.e., the spectrum of the emission wavelength of the phosphor. Specifically, if the peak of the spectrum of the emission wavelength of the phosphor shifts, the second wavelength band can also be shifted accordingly. For example, if the wavelength of 555 nm, at which visibility is high, is significantly different from the peak wavelength of the fluorescence, it is preferable to change the second wavelength band accordingly in accordance with the peak wavelength.

[0068] Furthermore, when white light is obtained by mixing blue light and yellow light, if the red component is insufficient, the white light may have a strong bluish green tint, and the appropriate chromaticity may not be obtained. In particular, the single-phase YAG:Ce used as the phosphor member 35 in this embodiment is prone to a lack of red. While it is conceivable to increase the reddish tint by increasing the Ce content or adding Gd (gadolinium), these are undesirable because they create voids within the phosphor member 35, causing internal scattering.

[0069] In this embodiment, the wavelength of red light is also set as a target wavelength for controlling the light distribution by the nanoantenna, and the light distribution of light with a wavelength corresponding to the reddish component is controlled to a narrow angle by the nanoantenna, concentrating the reddish component at the required light distribution angle, thereby producing the desired white light.

[0070] The emission spectrum of yellow fluorescence from a YAG:Ce phosphor generally exhibits a base where the intensity gradually decreases from approximately 600 nm to approximately 700 nm, which is included in the wavelength range of red light. In this embodiment, the wavelength range of red light is set to 600 nm or more and 700 nm or less (third wavelength band), and its center wavelength of 650 nm is set as the target wavelength (third wavelength) for light distribution control by the nanoantenna. That is, the period of nanoantenna 37C was set based on the results of analytically determining the period at which 650 nm light is most effectively diffracted. Specifically, the period of nanoantenna 37C can be determined by analyzing the intensity of 650 nm light emitted via nanoantenna 37 within ±30° in the direction perpendicular to the upper surface 35S of the phosphor member 35 using the RCWA method for various periods, and then selected based on the obtained light intensity. This allows for good diffraction of light from 600 to 700 nm, increasing the intensity of the light distributed within ±30° in the direction perpendicular to the upper surface 35S of the phosphor member 35.

[0071] Next, the setting of the array periods L1 to L3 will be described using Figure 3. Figure 3 shows the results of a simulation in which the proportion of light intensity within an emission angle of ±30° is calculated for each wavelength for a comparative example in which the nanoantenna array period is a single period in the lighting device of this embodiment. Figure 3 shows the proportion of light intensity within an emission angle of ±30° for the target wavelengths of 450 nm, 550 nm, and 650 nm, with the total light intensity in all directions (total luminous flux) set to 100% when the nanoantenna array period is changed.

[0072] FIG. 3A shows a comparative example (Comparative Example 1) in which a reflective member with different light scattering properties from the reflective member 39 of this embodiment is provided. The simulation results show that Lambertian scattering occurs on the side and back surfaces (i.e., the bottom surface) of the phosphor member 35. In this simulation, the percentage of light intensity within ±30° was calculated under the condition that 10% of the light is absorbed on the side and back surfaces of the phosphor member 35, and the remainder is Lambertian scattered (Lambertian scattering conditions). In other words, the simulation results show that 10% of the light reaching the side and back surfaces of the phosphor member 35 is absorbed, and 90% is Lambertian scattered and returns to the phosphor member 35. The reflective member of Comparative Example 1 is also referred to as a diffuse reflective film. In Comparative Example 1, it is assumed that the back surface of the phosphor member 35 or the bonding surface of the sapphire substrate 17 with the phosphor member 35 is roughened. In the following description of the simulation, a surface on which light reflection occurs under the above-mentioned Lambertian scattering conditions, that is, a surface on which 10% of the light that reaches the surface is absorbed and 90% is Lambertian scattered, is referred to as a Lambertian scattering surface.

[0073] FIG. 3B shows a comparative example (Comparative Example 2) in which a reflective member 39 similar to that of this embodiment is provided. This shows simulation results under conditions where specular reflection occurs on the side and back surfaces of the phosphor member 35 and where light is not absorbed (specular reflection conditions). In other words, this is a simulation result where 100% of the light reaching the side and back surfaces of the phosphor member 35 is specularly reflected and returned to the phosphor member 35. The reflective member of Comparative Example 2 is also referred to as a specular reflection film. In Comparative Example 2, it is assumed that the back surface of the phosphor member 35 or the bonding surface of the sapphire substrate 17 with the phosphor member 35 is a smooth surface, preventing scattering by the light emitting element 13. In the following description of the simulation, a surface where light reflection occurs under the specular reflection conditions described above, i.e., where all light reaching the phosphor member 35 is specularly reflected, is referred to as an ideal specular reflection surface.

[0074] The simulation was performed using the Rigorous Coupled Wave Analysis (RCWA) method and ray tracing. The simulation conditions were as follows: The phosphor member 35 was 1 mm square and had a thickness of 0.1 mm (i.e., 100 μm). The material of the nanoantenna was TiO ２ The nanoantennas were cylindrical in shape. The diameter of the nanoantennas was 80% of the period, and the height of the nanoantennas was constant at 300 nm. The nanoantennas were arranged in a triangular lattice pattern. The nanoantenna period was varied in 20 nm intervals from 300 nm to 540 nm for a wavelength of 450 nm, and from 360 nm to 540 nm for wavelengths of 550 nm and 650 nm.

[0075] As shown in Figure 3A, in Comparative Example 1, the proportion of light intensity within ±30° was a maximum of approximately 33%, while in Comparative Example 2, as shown in Figure 3B, the proportion of light intensity within ±30° exceeded 40% at each wavelength. Under the Lambertian scattering conditions of Comparative Example 1, the reflection angle changed relative to the incident angle each time light was reflected from the side or back surface of the phosphor member 35, which is thought to have reduced the amount of light incident on the upper surface 35S at angles greater than the critical angle at which diffraction is likely to occur. In other words, the proportion of light that passes through the phosphor member 35 without being diffracted and exits from the upper surface 35S increased, resulting in a reduced narrow-angle characteristic.

[0076] In contrast, under the specular reflection conditions of Comparative Example 2, specular reflection occurs on the side and back surfaces of the phosphor member 35, so that the amount of light incident on the upper surface 35S at angles greater than the critical angle is not reduced, making it easier for diffraction by the nanoantenna to occur, resulting in a higher narrow angle.

[0077] Although not shown, the total luminous flux was also higher in Comparative Example 2 than in Comparative Example 1. This result indicates that Comparative Example 2 has high light extraction efficiency because there is no light absorption.

[0078] Thus, while the proportion of light intensity within ±30° was high overall, there was a noticeable tendency for the period at which the proportion of light intensity within ±30° was highest to differ depending on the wavelength in Comparative Example 2. For example, in the period of 420 to 440 nm at which the proportion of light intensity within ±30° of the 550 nm wavelength, which has high luminosity, is highest, the proportion of light intensity within ±30° of light with a wavelength of 650 nm (red light) is approximately 10% lower than the proportion of light intensity within ±30° of light with a wavelength of 550 nm (green to yellow light).

[0079] Therefore, in Comparative Example 2, when the arrangement period of the nanoantennas is set to a single period of 420 to 440 nm, the light extracted at a narrow angle within ±30° becomes light that is less reddish and leans towards green.

[0080] Therefore, in this example, the nanoantenna arrangement periods L1 to L3 were selected to provide a high optical intensity ratio within ±30° for each of the wavelengths of 450 nm, 550 nm, and 650 nm. Specifically, the arrangement period L1 corresponding to a wavelength of 450 nm was set to 360 nm, the arrangement period L2 corresponding to a wavelength of 550 nm was set to 440 nm, and the arrangement period L3 corresponding to a wavelength of 650 nm was set to 500 nm.

[0081] By selecting the array period as described above, the intensity ratio of light emitted from region AR1, where nanoantennas are formed with array period L1, within ±30° of the direction perpendicular to the top surface 35S (0°) is the center, is highest for light with a wavelength of 450 nm. Furthermore, the intensity ratio of light emitted from region AR2, where nanoantennas are formed with array period L2, within ±30° of the direction perpendicular to the top surface 35S (0°) is the center, is highest for light with a wavelength of 550 nm. Furthermore, the intensity ratio of light emitted from region AR3, where nanoantennas are formed with array period L3, within ±30° of the direction perpendicular to the top surface 35S (0°) is the center, is highest for light with a wavelength of 650 nm.

[0082] In other words, of the light of wavelengths of 450 nm, 550 nm, and 650 nm included in the wavelength ranges of excitation light and fluorescence, light of wavelength 450 nm is most likely to have a narrow-angle light distribution in area AR1, light of wavelength 550 nm is most likely to have a narrow-angle light distribution in area AR2, and light of wavelength 650 nm is most likely to have a narrow-angle light distribution in area AR3.

[0083] Regarding the wavelength of 450 nm, in FIG. 3B, the light intensity ratio within ±30° is higher at 340 nm. However, since it becomes difficult to fabricate a nanoantenna under the conditions of this example at wavelengths less than 350 nm, 360 nm was selected as the array period L1.

[0084] 4A and 4B are diagrams showing the results of a simulation similar to that shown in FIGS. 3A and 3B, but with a nanoantenna height of 350 nm. FIG. 4A shows the simulation results for Comparative Example 3, and FIG. 4B shows the simulation results for Comparative Example 4. Comparative Example 3 was the same as Comparative Example 1 except for the nanoantenna height, and Comparative Example 4 was the same as Comparative Example 2 except for the nanoantenna height. Under the specular reflection conditions shown in FIG. 4B, the proportion of light intensity within ±30° tended to be higher overall than under the Lambertian scattering conditions shown in FIG. 4A, as in the cases of FIGS. 3A and 3B.

[0085] 4B, the period at which the light intensity ratio within ±30° is highest tends to differ for each wavelength, and the period at which the ratio is highest also tended to be similar to the case of the nanoantenna height of 300 nm shown in FIG. 3B. Therefore, it was found that the same nanoantenna arrangement periods L1 to L3 can be adopted even when the nanoantenna height is 350 nm.

[0086] 5A and 5B show simulation results of light distribution patterns (light distribution intensity distribution depending on the output angle). FIG. 5A shows the light distribution pattern of Comparative Example 5, in which the nanoantenna array period is a single period of 440 nm. FIG. 5B shows the light distribution pattern of this Example. In this Example, regions with three different nanoantenna array periods, array period L1: 360 nm, array period L2: 440 nm, and array period L3: 500 nm, are provided with approximately the same area, and the height of each nanoantenna is 300 nm. The diameter of the nanoantenna is 80% of the period in both Comparative Example 5 and this Example. For Comparative Example 5, the conditions other than the array period are the same as those of this Example.

[0087] 5A and 5B show the distribution of light intensity (luminous intensity) in directions of ±90°, with the direction perpendicular to the light exit surface being 0°. Furthermore, in Fig. 5A and 5B, the light intensity in each direction is normalized with the maximum light intensity of each wavelength being 100%.

[0088] 5A, the light distribution pattern differs for each wavelength. For example, the light distribution pattern of light with a wavelength of 550 nm (yellow light) tends to have high light intensity around ±20°, while the light distribution patterns of light with a wavelength of 450 nm (blue light) and light with a wavelength of 650 nm (red light) tend to have high light intensity around 0°. It is believed that such light distribution patterns cause color unevenness.

[0089] 5B, there is almost no deviation in the light distribution pattern for each wavelength, and the light distribution patterns are nearly identical. Therefore, this example achieves uniform white light. It is believed that color unevenness was reduced by dividing the upper surface 35S of the phosphor member 35 into three regions and setting the nanoantenna arrangement period in each region to L1 to L3, which facilitates narrowing the angle for each wavelength.

[0090] Figures 6A and 6B show the results of a simulation of the same light distribution pattern as shown in Figures 5A and 5B, with the nanoantenna height set to 350 nm. Both Figures 6A and 6B show the same trends as those in Figures 5A and 5B.

[0091] Specifically, in Fig. 6A, where the nanoantennas are arranged at a single period, the light distribution pattern differs for each wavelength. In Fig. 6B, where the nanoantennas are arranged at multiple periods according to the present embodiment, the light distribution pattern is nearly consistent for each wavelength, indicating that uniform white light with little color unevenness can be obtained.

[0092] [Manufacturing Method] An example of a manufacturing method for the wavelength conversion member 15 and the lighting device 100 of this embodiment will be described. First, a dielectric film is formed on the upper surface of a flat phosphor plate by electron beam evaporation or sputtering. The material of the dielectric film is the material of the nanoantenna, and is a material with a high refractive index so as to increase the scattering intensity, such as TiO. ２ In this case, the thickness of the dielectric film is the height H of the nanoantennas 37A to 37C.

[0093] Next, a metal film made of aluminum (Al) is formed on the dielectric film, and a resin resist is applied to the metal film to form a resist film. A nanoantenna pattern is formed by nanoimprinting. A resin nanoimprinting mold (replica mold) with multiple holes corresponding to the shape and dimensions of the nanoantenna is pressed against the resist film and then peeled off, thereby patterning the resist film. A master mold is fabricated on, for example, a silicon substrate by electron beam lithography, and a replica mold is fabricated from the master mold by nanoimprinting.

[0094] For example, by using a master mold in which pillar patterns with different diameters and arrangement periods are provided for each region, it is possible to form a pattern of multiple nanoantenna groups arranged at different arrangement periods. Specifically, a master mold is used in which nanoantenna patterns with arrangement periods L1 to L3 are formed in predetermined regions corresponding to regions AR1 to AR3.

[0095] Next, dry etching is performed using the patterned resist film as a mask to etch the metal film, thereby forming a metal mask for etching the dielectric film.

[0096] Next, the dielectric film on which the metal mask is formed is etched by dry etching. For example, when the metal film is made of Al and the dielectric film is made of TiO ２ In this case, an etching gas of chlorine (Cl) and argon (Ar) is used for the metal film, and carbon tetrafluoride (CF ４ ), Ar and oxygen (O ２ ) or other etching gases are used.

[0097] By removing the metal mask remaining after the above process by dry etching or wet etching, the nanoantennas 37A to 37C having different arrangement periods as described above can be formed.

[0098] Thereafter, a protective resist is applied to the surface of the phosphor plate on which the nanoantenna is formed, and the phosphor plate is cut by dicing into pieces of the desired size of the phosphor member 35 (1 mm square in this embodiment).

[0099] The surface of the individualized phosphor plate, i.e., phosphor member 35, opposite the resist surface is fixed to a support substrate, and a dielectric multilayer film 41 is formed on the side surface (cut end surface) by atomic layer deposition (ALD).

[0100] As described above, the dielectric material is a low refractive index material such as silicon oxide (SiO ２ ), alumina (Al ２ O ３ As a high refractive index material, titanium oxide (TiO ２ ), zirconia (ZrO ２ ), niobium pentoxide (Nb ２ O ５ ), lanthanum oxide (La ２ O ３ ), tantalum oxide (Ta ２ O ５ ), hafnium oxide (HfO ２ It is preferable to use a material with low absorption such as

[0101] Thereafter, a metal reflective film is formed on the surface of the dielectric multilayer film 41 by electron beam evaporation or sputtering. Aluminum (Al) or silver (Ag), which have high reflectivity, is preferred as the metal material. Furthermore, sputtering is preferred for forming a metal film with a uniform thickness on the side surface (end surface) of the phosphor member 35. In this manner, the wavelength conversion member 15 including the nanoantennas 37A to 37C and the reflective member 39 can be manufactured.

[0102] Thereafter, the protective resist for the nanoantenna is removed, the phosphor member 35 is removed from the support substrate, and the phosphor member 35 is bonded to the upper surface of the substrate 17 of the light-emitting element 13. The phosphor member 35 may be bonded to the substrate 17 via a transparent resin, or may be directly bonded by plasma activated bonding or surface activated bonding. In this manner, the lighting device 100 can be manufactured.

[0103] As described above, after the phosphor plate is divided into individual pieces, it may be bonded to the upper surface of the substrate 17 of the light-emitting element 13 before forming the reflective member 39, and then the dielectric multilayer film 41 and the metal film 43 may be formed on the side surfaces of the light-emitting element 13 and the phosphor member 35. In this way, it is possible to manufacture the lighting device 100 in which the reflective member 39 is also formed on the side surfaces of the substrate and semiconductor layer of the light-emitting element 13 as shown in FIG.

[0104] In this embodiment, an example has been described in which the wavelength conversion member 15 has three regions AR1 to AR3, and a region having one type of nanoantenna period is provided within one region, but this is not limited to this. In the wavelength conversion member 15, the region having one type of nanoantenna period may be provided in multiple regions. For example, multiple regions AR1, multiple regions AR2, and multiple regions AR3 may be provided in a matrix.

[0105] In this embodiment, the area ratios S1 to S3 of the regions AR1 to AR3 to the area of ​​the upper surface 35S of the phosphor member 35 are all set to 1 / 3, but this is not limited to this. By changing the area ratio, it is possible to change the output intensity of light of each target wavelength and adjust the color. The higher the area ratio, the higher the light intensity within ±30° of the light of the corresponding wavelength.

[0106] For example, by making the area ratio S3 of the region AR3 larger than the area ratios S1 and S2 of the regions AR1 and AR2, respectively, the light intensity of the red light can be increased. For example, as described above, when the red light component is insufficient due to the properties of the YAG:Ce phosphor, by increasing the area ratio S3, it is possible to obtain, for example, white light with high visibility and close to blackbody radiation. This makes it possible to satisfy, for example, the specifications for the red light component of an automobile headlamp.

[0107] Furthermore, for example, when it is not necessary to actively extract the red light component, it is possible to provide only two types of regions, AR1 and AR2, and not provide region AR3.

[0108] As described above, the wavelength conversion member 15 of this embodiment includes a flat phosphor member 35 containing a phosphor that emits fluorescence when excited by excitation light, a reflective member that is provided on a side surface 35E of the phosphor member 35 and reflects the excitation light and fluorescence, and a plurality of nanoantennas made of a metal material or a dielectric material that are provided on a top surface 35S that is one main surface of the phosphor member. In a plan view seen from a direction perpendicular to the top surface 35S, the plurality of nanoantennas are arranged in a lattice pattern with arrangement periods L1 to L3 that are determined for each of regions AR1 to AR3 on the top surface 35S.

[0109] The arrangement periods in the regions AR1 to AR3 correspond to the wavelengths 450 nm, 550 nm, and 650 nm, respectively, included in the wavelength ranges of the excitation light and fluorescence, and these wavelengths are wavelengths included in multiple wavelength bands that do not overlap with each other.

[0110] In other words, the nanoantennas of this embodiment include a plurality of nanoantenna groups having mutually different arrangement periods. Specifically, the nanoantennas of this embodiment include a first nanoantenna group in which a plurality of nanoantennas 37A are arranged in a lattice pattern with an arrangement period L1 as a first arrangement period, a second nanoantenna group in which a plurality of nanoantennas 37B are arranged in a lattice pattern with an arrangement period L2 as a second arrangement period, and a third nanoantenna group in which a plurality of nanoantennas 37C are arranged in a lattice pattern with an arrangement period L3 as a third arrangement period.

[0111] In this embodiment, the arrangement period L1 corresponds to a wavelength of 450 nm as a first wavelength, which is a wavelength selected from a wavelength band of 430 nm or more and 470 nm or less as a first wavelength band.

[0112] The arrangement period L2 corresponds to a wavelength of 550 nm as a second wavelength included in the wavelength range of the excitation light and the fluorescence, and the second wavelength is a wavelength selected from the second wavelength band of 530 nm to 570 nm.

[0113] The arrangement period L3 corresponds to a wavelength of 650 nm, which is a third wavelength included in the wavelength range of the excitation light and the fluorescence. The third wavelength is a wavelength selected from a third wavelength band of 600 nm to 700 nm.

[0114] The region AR1, which is a first region, is a region where the first nanoantenna group is formed on the top surface 35S, which is one of the main surfaces of the phosphor member 35. Of the light emitted from the first region, the intensity ratio of light emitted within a predetermined angular range centered on a direction perpendicular to the top surface of the phosphor member 35 is such that the light of the first wavelength is greater than the light of the second wavelength, and the light of the first wavelength is greater than the light of the third wavelength.

[0115] Furthermore, the region where the second nanoantenna group is formed on the upper surface 35S of the phosphor member 35 is a region AR2 serving as a second region. With regard to the intensity ratio of the light emitted from the second region within a predetermined angle range centered on a direction perpendicular to the upper surface 35S of the phosphor member 35, the light of the second wavelength has a higher intensity ratio than the light of the first wavelength, and the light of the second wavelength has a higher intensity ratio than the light of the third wavelength.

[0116] Furthermore, the region where the third nanoantenna group is formed on the upper surface 35S of the phosphor member 35 is a region AR3 as a third region. With regard to the intensity ratio of the light emitted from the third region within a predetermined angle range centered on a direction perpendicular to the upper surface 35S of the phosphor member 35, the light of the third wavelength has a higher intensity ratio than the light of the first wavelength, and the light of the third wavelength has a higher intensity ratio than the light of the second wavelength.

[0117] The lighting device of this embodiment has a configuration in which the light emitting element 13 flip-chip mounted on a mounting substrate is used as a light source, and the wavelength conversion member 15 of this embodiment is bonded onto the substrate 17 of the light emitting element 13. Specifically, the lower surface of the phosphor member 35, which is the surface opposite to the upper surface on which the nanoantenna is formed, is bonded onto the substrate 17.

[0118] With the above-described configuration, when the light distribution pattern of the lighting device of this embodiment is viewed for each wavelength corresponding to the arrangement period of the nanoantennas in each nanoantenna group, the phenomenon in which the light distribution pattern differs for each wavelength, as seen in the case of a single period, is mitigated, and a narrow-angle light distribution with little color unevenness is obtained.

[0119] In this example, an example has been described in which first to third nanoantenna groups are provided with periods corresponding to wavelengths of 450 nm, 550 nm, and 650 nm, which have different colors and are included in the wavelength ranges of the excitation light and the fluorescence, but the wavelength conversion member of the present invention is not limited to this. It is sufficient that the wavelength conversion member includes at least two nanoantenna groups.

[0120] For example, as described above, two nanoantenna groups may be provided at periods corresponding to wavelengths of 450 nm and 550 nm, respectively, or two nanoantenna groups may be provided at periods corresponding to wavelengths of 550 nm and 650 nm.

[0121] In other words, in the wavelength conversion member of the present invention, the multiple nanoantennas include a first group of nanoantennas arranged in a lattice pattern with a first arrangement period, and a second group of nanoantennas arranged in a lattice pattern with a second arrangement period.

[0122] The first array period is a period corresponding to a first wavelength included in the wavelength range of the excitation light and the fluorescence, and the second array period is a period corresponding to a second wavelength included in the wavelength range of the excitation light and the fluorescence.

[0123] For example, the first wavelength may be 450 nm corresponding to blue light and the second wavelength may be 550 nm corresponding to yellow light, or in other words, the first wavelength may be selected from a first wavelength band and the second wavelength may be selected from a second wavelength band.

[0124] Alternatively, the first wavelength may be 550 nm corresponding to yellow light, and the second wavelength may be 650 nm corresponding to red light, or in other words, the first wavelength may be selected from the second wavelength band, and the second wavelength may be selected from the third wavelength band.

[0125] The intensity ratio of light emitted from a first region in which a first group of nanoantennas is formed on the top surface 35S, which is one of the main surfaces of the phosphor member 35, within a predetermined angular range centered on a direction perpendicular to the top surface 35S is greater for light of the first wavelength than for light of the second wavelength.

[0126] Furthermore, the intensity ratio of light emitted from the second region on the upper surface 35S of the phosphor member 35 in which the second nanoantenna group is formed within a predetermined angular range centered on a direction perpendicular to the upper surface 35S is greater for light of the second wavelength than for light of the first wavelength.

[0127] The above configuration provides a narrow-angle light distribution, high output, and mixed-color light with minimal color unevenness. For example, by selecting the arrangement period of at least two nanoantenna groups as described above according to the desired chromaticity, white light of the desired color can be obtained.

[0128] Therefore, according to this embodiment, it is possible to provide a wavelength conversion member that can constitute an illumination device with a narrow light angle, high output, and little color unevenness, and an illumination device using the same.

[0129] As described above, the inventors of the present application discovered that when mixing light of a wide wavelength range including light of different colors, the tendency for the period of nanoantennas, which are prone to narrowing the angle, to vary depending on the wavelength, becomes more pronounced by providing a reflective member that causes specular reflection. Then, to make each of the multiple wavelengths of light of different colors more susceptible to diffraction by the nanoantennas, multiple regions are provided on the upper surface of the wavelength conversion member, and nanoantennas arranged at multiple arrangement periods are provided in each of the different regions. This reduces the difference in light distribution pattern for each wavelength, resulting in mixed color light with less color unevenness.

[0130] In this embodiment, the reflective member 39 is described as being made up of the dielectric multilayer film 41 formed to cover the side surfaces of the phosphor member 35 and the metal film 43 formed on the dielectric multilayer film 41, but is not limited to this. For example, the reflective member 39 may be made up of only the dielectric multilayer film 41 covering the side surfaces of the phosphor member 35, or only the metal film 43 covering the side surfaces of the phosphor member 35.

[0131] Even in this way, in the lighting device 100, the differences in light distribution patterns for each wavelength are mitigated by multiple nanoantenna groups with different arrangement periods, and the effect of the present invention is achieved, in that mixed color light with a narrow light angle, high output, and little color unevenness is emitted.

[0132] The reflecting member 39 is a member (also referred to as a specular reflecting member) that generates a certain amount of what is generally called specularly reflected components when reflecting light that has reached the side surface of the phosphor member 35. For example, the reflecting member 39 is a member in which the specularly reflected component is the main component of the reflected light.

[0133] In other words, the present invention does not assume that the reflective member 39 is made entirely of a material that causes diffuse reflection, such as a member made entirely of white resin.

[0134] It should be noted that even if a portion of the reflective member 39 contains a portion that causes diffuse reflection, such as white resin, it is sufficient as long as a certain level of regular reflection component is generated as a whole. For example, instead of the metal film 43, a resin member made of white resin may be formed on the dielectric multilayer film 41 to form the reflective member 39. The white resin may be, for example, a silicone resin containing titanium oxide (TiO ２ ) is dispersed.

[0135] As described above with respect to the simulations of Figures 3A and 3B, the proportion of light extracted at a narrow angle is greater when the rear and side surfaces of the phosphor member 35 are ideal specular reflecting surfaces than when they are Lambertian scattering surfaces.

[0136] In the configuration of this embodiment having a reflective member 39, from the viewpoint of increasing the light flux extracted at a narrow angle, a simulation was conducted using a comparative example to examine what the required specular reflectance of light reaching the side surface of the phosphor member 35 should be.

[0137] As a result of the study, it was found that the specular reflectance of the side surface of the fluorescent member is preferably 80% or more. It was concluded that if the specular reflectance of the side surface of the fluorescent member is 80% or more, the light extraction efficiency within an emission angle of ±30° can be increased to a level equal to or greater than that when the reflection mode on the back surface and side surface is diffuse reflection. The details of the study are explained below.

[0138] Specifically, the light extraction efficiency within ±30° was calculated from the light extraction efficiency and the proportion of luminous flux within ±30°, and the luminous flux extracted at a narrow angle was evaluated using the light extraction efficiency within ±30°. In other words, the evaluation and study were conducted assuming that the higher the light extraction efficiency within ±30° (hereinafter also referred to as narrow-angle extraction efficiency) is, the higher the luminous flux extracted at a narrow angle is. The light extraction efficiency was defined as the proportion of the total luminous flux of light emitted from the wavelength conversion member to the radiant intensity of the light-emitting element.

[0139] The light extraction efficiency was calculated by a simulation using the RCWA (Rigorous Coupled Wave Analysis) method and ray tracing. The lighting device conditions (model) used in the simulation were as follows: The phosphor member was a single-phase transparent ceramic phosphor plate made of yttrium aluminum garnet (YAG:Ce) phosphor with cerium (Ce) as an activator, and the nanoantenna was made of titanium dioxide. The size of the phosphor member was 1 mm square and 0.1 mm thick. The nanoantennas were arranged in a triangular lattice pattern with a period of 420 nm, had a cylindrical shape, and their particle diameter was 80% of the period. The calculation was performed assuming a light wavelength of 550 nm. The configurations of the light-emitting element and reflector were the same as in Example 1.

[0140] 7 is a graph showing the results of a simulation in which the specular reflectance of the rear surface of the phosphor member is fixed at 92% (8% is absorption) and the specular reflectance of the side surfaces is varied from 80% to 100% in this model. The light extraction efficiency in Fig. 7 is shown as 100%, based on the light extraction efficiency when the diffuse reflectance of the rear surface is 92% (8% is absorption) and the specular reflectance of the side surfaces is 100%.

[0141] The condition where the diffuse reflectance of the rear surface is 92% and the regular reflectance of the side surface is 100% is the condition where the light extraction efficiency is maximized in the practical configuration of this example, and was therefore used as the standard for this study.

[0142] 3A and 3B, data for the condition where the light wavelength λ is 550 nm and the nanoantenna pitch is 420 nm was used as the luminous flux ratio within ±30°. As described above, Fig. 3A shows the light intensity ratio (i.e., luminous flux ratio) within ±30° when the side and back surfaces of the phosphor member 35 are Lambertian scattering surfaces (Lambertian scattering condition).

[0143] The Lambertian scattering conditions in Fig. 3A are conditions under which the light extraction efficiency is approximately equal to the standard conditions for light extraction efficiency in this study, i.e., the condition of a diffuse reflectance of 92% on the back surface and a specular reflectance of 100% on the side surfaces. Therefore, the light extraction efficiency for λ = 550 nm and a period of 420 nm in Fig. 3A is also set to 100%.

[0144] 3A, the luminous flux ratio within ±30° at a wavelength λ of 550 nm and a period of 420 nm is approximately 31%. In this case, the light extraction efficiency within an emission angle of ±30° (narrow-angle extraction efficiency) is 31%, which is obtained by multiplying the light extraction efficiency (100%) by the luminous flux ratio within ±30° (31%).

[0145] 3B shows the luminous flux ratio within ±30° when the side and back surfaces of the phosphor member 35 are ideal specular reflection surfaces (specular reflection conditions). From FIG. 3B, the luminous flux ratio within ±30° when the wavelength λ is 550 nm and the period is 420 nm is approximately 41%. In this study, the luminous flux ratio within ±30° of the above model is treated as being constant at approximately 41%, regardless of the specular reflectance of the side surfaces, and is considered to be the same as that in the case of an ideal specular reflection surface.

[0146] In this simulation, the side and back surfaces of the model phosphor member 35 are not ideal specular reflection surfaces, but are surfaces where specular reflection is dominant, and are therefore referred to as specular reflection surfaces. In contrast, surfaces where diffuse reflection of the light that reaches them is dominant, including Lambertian scattering surfaces, are also referred to as diffuse reflection surfaces.

[0147] The light extraction efficiency (narrow-angle extraction efficiency) within an emission angle of ±30° for the above model is calculated to be approximately 75% when the side and back surfaces of the phosphor member 35 are Lambertian scattering surfaces, which is equivalent to the narrow-angle extraction efficiency (31%). From Figure 7, it can be said that the side specular reflectance at which the light extraction efficiency is approximately 75% is approximately 80%. Table 1 shows the luminous flux ratio within ±30°, light extraction efficiency, and narrow-angle extraction efficiency for the Lambertian scattering surface and the simulation model under each condition when the narrow-angle extraction efficiency is equivalent.

[0148]

[0149] In other words, in Figure 3, it has been confirmed that the luminous flux ratio within ±30° when the period is 420 nm is approximately 75% when the side and back surfaces of the phosphor member are Lambertian scattering surfaces (i.e., diffuse reflection surfaces) (31%) and 75% when the side and back surfaces are specular reflection surfaces (41%). Therefore, according to the correspondence relationship in Table 1, when the light extraction efficiency in the case of specular reflection is approximately 75% of that in the case of diffuse reflection (100%), the extraction efficiency within ±30° is equivalent. The side specular reflectance in this case is approximately 80% as shown in Figure 7. Therefore, by having a side specular reflectance of 80% or more, the luminous flux within ±30° can be increased to a level equal to or greater than when the side and back surfaces are diffuse reflection surfaces.

[0150] Furthermore, in order to increase the specular reflection component, it is desirable that the side and back surfaces of the phosphor member 35 are mirror-finished. If the surface roughness Ra, which is the standard for a general mirror finish, is 0.2 μm or less, the specular reflection component can be increased to, for example, a specular reflectance of approximately 92%.

[0151] The reflecting member 39 may be configured so that the specular reflection member covers at least a portion of the side surface of the phosphor member 35. For example, the reflecting member 39 may be configured so that the dielectric multilayer film 41 covers a portion of the side surface of the phosphor member 35, the metal film 43 is formed on the dielectric multilayer film 41, and a portion made of white resin that covers the remaining portion of the side surface of the phosphor member 35. Even in this case, the reflecting member 39 as a whole may be configured so that a certain amount or more of specularly reflected components are generated.

[0152] 8 is a top view of a lighting device 200 including a wavelength conversion member 51 according to a second embodiment of the present invention. The lighting device 200 has the same configuration as the lighting device 100 of the first embodiment, except that it has a wavelength conversion member 51 instead of the wavelength conversion member 15. The wavelength conversion member 51 has the same configuration as the wavelength conversion member 15 of the first embodiment, except for the arrangement period and arrangement mode of the nanoantennas.

[0153] In the wavelength conversion member 51, the blue light emitted from the upper surface 35S of the phosphor member 35 is blue light that has not been excited by the phosphor, i.e., not absorbed, and therefore the intensity of the blue light can be adjusted by changing the thickness of the phosphor. Specifically, the intensity of the blue light can be increased by reducing the thickness of the phosphor.

[0154] Furthermore, blue light tends to have a relatively narrow light distribution angle because light with a short optical path length and an emission angle of 0° tends to be easily extracted from the upper surface 35S. In other words, it can be said that the light intensity within ±30° can be adjusted by the thickness of the phosphor member 35 without narrowing the angle using a nanoantenna.

[0155] Therefore, in this example, blue light is not the target for angle narrowing by the nanoantenna, and two wavelengths corresponding to the wavelengths of yellow light and red light are the target wavelengths for angle narrowing by the nanoantenna. As in Example 1, the target wavelength included in the wavelength range of yellow light is set to 550 nm, and the array period L2 that easily diffracts light with a wavelength of 550 nm is set to 440 nm. Furthermore, the target wavelength included in the wavelength range of red light is set to 650 nm, and the array period L3 that easily diffracts light with a wavelength of 650 nm is set to 500 nm.

[0156] 8, the wavelength conversion member 51 has two regions on the upper surface 35S of the phosphor member 35: a region AR2 in which nanoantennas 37B are arranged at an arrangement period L2, and a region AR3 in which nanoantennas 37C are arranged at an arrangement period L3. The area ratios S2 and S3 of the region AR2 and the region AR3 to the entire region in which the nanoantennas are formed are both 1 / 2.

[0157] The lighting device 200 including the wavelength conversion member 51 of this embodiment provides a narrow-angle light distribution pattern with high light intensity within ±30° and white light with little color unevenness. In the example shown in Fig. 8, the area ratios S2 and S3 are both set to 1 / 2, but this is not limiting. The color of the mixed color light may be adjusted by increasing either area ratio. For example, by making the area ratio S3 of the region AR3 corresponding to red light larger than the area ratio S2 of the region AR2 corresponding to yellow light, white light containing a sufficient amount of red light can be obtained.

[0158] 9 is a top view of a lighting device 201 including a wavelength conversion member 61 according to Modification 1 of Example 2. The wavelength conversion member 61 has the same configuration as the wavelength conversion member 51 of Example 2, except for the arrangement period and arrangement mode of the nanoantennas.

[0159] 9 , in this first modification, the regions AR2 and AR3 are each divided into two and arranged in a matrix when viewed from the top of the wavelength conversion member 61. In other words, the region AR2 as a first region and the region AR3 as a second region are arranged in a matrix when viewed from a direction perpendicular to the top surface 35S of the phosphor member 35. By arranging the regions AR2 and AR3 in this manner, color unevenness can be reliably reduced.

[0160] 9, when one type of region, i.e., a region in which nanoantenna groups with the same arrangement period are formed, is divided into multiple regions, the area ratio of one type of region to the entire region in which nanoantennas are formed is the ratio of the total area of ​​each of the multiple divided regions. For example, the area ratio S2 of region AR2 is the ratio of the total area of ​​the multiple regions AR2. In the example shown in FIG. 9, the area ratio S2 of region AR2 and the area ratio S3 of region AR3 are equal, both being 1 / 2 (S2 = S3).

[0161] Note that each of the regions AR2 and AR3 is not limited to being divided into two, but may be divided into three or more regions and arranged in a matrix. However, from the viewpoint of narrow-angle light distribution, a configuration with fewer boundaries between the regions is preferable because it allows the narrow angle to be maintained.

[0162] 10 is a top view of a lighting device 202 including a wavelength conversion member 71 according to Modification 2 of Example 2. The wavelength conversion member 71 has the same configuration as the wavelength conversion member 51 of Example 2, except for the arrangement period and arrangement mode of the nanoantennas.

[0163] As shown in Fig. 10 , in this second modification, the regions AR2 and AR3 are concentrically arranged in a top view of the wavelength conversion member 71. In other words, the region AR2 as the first region and the region AR3 as the second region are concentrically arranged in a plan view seen from a direction perpendicular to the top surface 35S of the phosphor member 35. By arranging the regions AR2 and AR3 in this manner, color unevenness can be reliably reduced. Note that, although Fig. 10 shows an example in which the region AR3 is arranged inside the region AR2, this is not limiting, and either region may be arranged inside.

[0164] 10, when the phosphor member 35 is divided into individual pieces after the nanoantennas are formed, the cutting positions are all boundaries between regions having the same nanoantenna arrangement period. Therefore, even if variations occur in the cutting positions, the impact is smaller than when cutting at a boundary between regions having different nanoantenna arrangement periods, and the yield can be increased.

[0165] The configurations in the above-described embodiments and modifications are merely examples, and can be modified or combined as appropriate depending on the application, etc.

[0166] For example, in the above-described embodiments and modifications, the conditions such as the arrangement period of the nanoantennas, the arrangement of the regions in which the nanoantenna groups are arranged, and the area ratio of each region are not limited to the above-described examples, and can be appropriately adjusted according to the wavelength of the light emitted from the light source, the desired light distribution, the desired color, etc. Furthermore, the arrangement pattern of the nanoantennas is not limited to the above-described triangular lattice shape, and may be, for example, a square lattice shape.

[0167] REFERENCE SIGNS LIST 100, 200 Lighting device 11 Mounting substrate 13 Light-emitting element 15 Wavelength conversion device 17 Sapphire substrate 19 N-type semiconductor layer 21 Active layer 23 P-type semiconductor layer 25 Semiconductor laminate 27 P-electrode 29 P-type electrode pad 31 N-electrode 33 N-type electrode pad 35 Phosphor member 37A, 37B, 37C Nanoantenna 39 Reflecting member 41 Dielectric multilayer film 43 Metal film

Claims

1. A fluorescent element comprising: a flat-plate-shaped fluorescent member including a fluorescent material that emits fluorescence when excited by excitation light; a reflecting member provided on a side surface of the fluorescent member and reflecting the excitation light and the fluorescence; and a plurality of nanoantennas made of a metallic material or a dielectric material provided on one main surface of the fluorescent member, wherein the plurality of nanoantennas include a first group of nanoantennas arranged in a lattice pattern with a first arrangement period and a second group of nanoantennas arranged in a lattice pattern with a second arrangement period, wherein the first arrangement period is a period corresponding to a first wavelength included in the wavelength ranges of the excitation light and the fluorescence, and the second arrangement period is a period corresponding to a second wavelength included in the wavelength ranges of the excitation light and the fluorescence, and wherein the intensity ratio of light emitted from a first region of the fluorescent member in which the first group of nanoantennas is formed within a predetermined angle range centered on a direction perpendicular to the main surface is such that the light of the first wavelength is greater than the light of the second wavelength, A wavelength conversion member characterized in that the intensity ratio of light emitted from a second region in which the second nanoantenna group is formed in the phosphor member within a predetermined angular range centered on a direction perpendicular to the main surface is greater for light of the second wavelength than for light of the first wavelength.

2. The wavelength conversion member according to claim 1, wherein the excitation light has a peak wavelength of 430 nm or more and 470 nm or less, the fluorescence has a peak wavelength of 520 nm or more and 570 nm or less and has a base range of 600 nm or more and 700 nm or less, and the first wavelength and the second wavelength are included in different wavelength bands selected from a first wavelength band of 430 nm or more and 470 nm or less, a second wavelength band of 530 nm or more and 570 nm or less, and a third wavelength band of 600 nm or more and 700 nm or less.

3. The wavelength conversion member according to claim 2, wherein the first wavelength is selected from the first wavelength band, and the second wavelength is selected from the second wavelength band.

4. The wavelength conversion member according to claim 2, wherein the first wavelength is selected from the second wavelength band, and the second wavelength is selected from the third wavelength band.

5. The plurality of nanoantennas includes a third nanoantenna group arranged at a third arrangement period, the third arrangement period being a period corresponding to a third wavelength included in the wavelength ranges of the excitation light and the fluorescence, the first wavelength being selected from the first wavelength band, the second wavelength being selected from the second wavelength band, and the third wavelength being selected from the third wavelength band, the intensity ratio of light emitted from the first region within a predetermined angle range centered on a direction perpendicular to the main surface being greater for the light of the first wavelength than for the light of the second wavelength or the light of the third wavelength, the intensity ratio of light emitted from the second region within a predetermined angle range centered on a direction perpendicular to the main surface being greater for the light of the second wavelength than for the light of the first wavelength or the light of the third wavelength, the intensity ratio of light emitted in the phosphor member from a third region in which the third nanoantenna group is formed within a predetermined angle range centered on a direction perpendicular to the main surface being greater for the light of the third wavelength than for the light of the first wavelength or the light of the second wavelength, The wavelength conversion member according to claim 2 , wherein the area of ​​the third region is larger than the area of ​​the first region and the area of ​​the second region.

6. A wavelength conversion member as described in claim 1, characterized in that the first region and the second region are strip-shaped regions each arranged along a direction in a plan view perpendicular to the first main surface of the phosphor member.

7. A wavelength conversion member according to claim 1, characterized in that the first region and the second region are arranged in a matrix in a planar view seen from a direction perpendicular to the first main surface of the phosphor member.

8. A wavelength conversion member according to claim 1, characterized in that the first region and the second region are arranged concentrically in a planar view seen from a direction perpendicular to the first main surface of the phosphor member.

9. A wavelength conversion member as described in claim 1, characterized in that each of the plurality of nanoantennas has a maximum width in the first region that is 75% to 85% of the first arrangement period when viewed in a planar view perpendicular to the first main surface of the phosphor member, and has a maximum width in the second region that is 75% to 85% of the second arrangement period.

10. A wavelength conversion member according to claim 1, characterized in that the reflecting member comprises a multilayer film reflector formed on the side surface and a metal film formed on the multilayer film reflector.

11. A lighting device comprising: a wavelength conversion member according to claim 1; a substrate; and a light source comprising a semiconductor laminate formed on the substrate in this order: a first semiconductor layer having a first conductivity type, an active layer, and a second semiconductor layer having a second conductivity type different from the first conductivity type; wherein the substrate is translucent to light emitted from the active layer and is bonded to the surface of the phosphor member opposite to the first main surface.

12. The lighting device according to claim 11, wherein the reflecting member is provided on a side surface of the substrate and a side surface of the semiconductor laminate.

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