Wavelength conversion device and lighting device

Abstract

The wavelength conversion device has a phosphor member having one surface on which excitation light is incident, containing a phosphor that emits fluorescent light when excited by the excitation light, and having an uneven structure on the other surface opposite to the one surface, the uneven structure including a plurality of protruding portions, and a plurality of nano-antennas disposed on the other surface, the plurality of protruding portions disposed in the first direction at a period smaller than a peak wavelength of fluorescence along the other surface, and the plurality of nano-antennas being made of a metal member disposed on upper surfaces of the plurality of protruding portions.

Description

Technical Field

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

[0002] A lighting device has been disclosed that uses a metal antenna made of nano-sized metal particles (hereinafter referred to as a nanoantenna) to narrow the angle of light. For example, Patent Document 1 discloses a lighting device that includes a transparent substrate, a wavelength converter provided on the transparent substrate, and a plurality of nanoantennas formed on the wavelength converter.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2014-508379. Summary of the invention

[0004] Technical issues

[0005] In the lighting device disclosed in Patent Document 1, the component of the fluorescence generated by the phosphor in the wavelength converter being excited by the excitation light that exceeds the critical angle is totally reflected by the interface between the wavelength converter and the air. At this time, there is a problem that a part of the totally reflected fluorescence is repeatedly reflected multiple times inside the wavelength converter without being extracted to the outside, and then absorbed by the nanoantenna, thereby reducing the light extraction efficiency of the entire lighting device.

[0006] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a wavelength conversion device and a lighting device capable of improving light extraction efficiency while realizing a narrow angle of fluorescence using a nano-antenna.

[0007] Technical Solution

[0008] The wavelength conversion device according to the present invention includes a phosphor member and a plurality of nano-antennas. The phosphor member has one surface on which excitation light is incident, includes a phosphor excited by the excitation light to emit fluorescence, and has an uneven structure on another surface on the opposite side of the one surface. The uneven structure includes a plurality of protrusions, each of which is arranged along the other surface in one direction at a pitch less than the peak wavelength of the fluorescence. A plurality of nano-antennas are arranged at the upper surface of the plurality of protrusions and are made of a metal material. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0012] Figure 4 is a graph showing transmission intensity with respect to the depth of a recessed portion in the wavelength conversion device according to the first embodiment.

[0013] Figure 5 is a graph showing transmission intensity with respect to the depth of a recessed portion in the wavelength conversion device according to the first embodiment.

[0014] Figure 6 is a graph showing the penetration length of evanescent light with respect to the incident angle in the wavelength conversion device according to the first embodiment.

[0015] Figure 7 is a top view of a wavelength conversion device according to a modification of the first embodiment.

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

[0017] Fig. 9 is a cross-sectional view of a lighting device according to a third embodiment.

[0018] Fig.10 is a cross-sectional view of a wavelength conversion device according to a third embodiment. DETAILED DESCRIPTION

[0019] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals are attached to the same components, and explanations of overlapping components will be omitted.

[0020] First embodiment

[0021] Reference Figure 1 and Figure 2 , describes the configuration of the wavelength conversion device 100 according to the first embodiment. Figure 1 is a top view of the wavelength conversion device 100 according to the first embodiment. Figure 2 is along Figure 1 A cross-sectional view of the wavelength conversion device 100 is shown along line 2-2.

[0022] [Mounting substrate]

[0023] The mounting substrate 12 is an insulating flat plate-like substrate having a rectangular upper surface shape. The mounting substrate 12 is made of, for example, aluminum nitride (AlN), aluminum oxide (Al2O3), etc. Hereinafter, for convenience of explanation, the X-axis, Y-axis, and Z-axis are defined by taking the direction perpendicular to the upper surface of the mounting substrate 12 as the Z-axis, and taking the directions along the respective two sides perpendicular to each other of the mounting substrate 12 as the X-axis and the Y-axis.

[0024] [Light-emitting element]

[0025] The light emitting element 13 is a light emitting diode (LED) mounted on the upper surface of the mounting substrate 12 and having a rectangular upper surface shape. The light emitting element 13 includes a semiconductor structure layer 14 having a light emitting layer, a support substrate 15 disposed on the upper surface of the semiconductor structure layer 14, and a p-electrode 16 and an n-electrode 17 disposed on the lower surface of the semiconductor structure layer 14 and bonded to the mounting substrate 12. That is, the light emitting element 13 is flip-chip mounted to the mounting substrate 12.

[0026] The semiconductor structure layer 14 is a semiconductor stack including an n-type semiconductor layer, a light-emitting layer and a p-type semiconductor layer (all not shown) each containing gallium nitride (GaN) as a main material. When the light-emitting element 13 is driven, the light-emitting layer of the semiconductor structure layer 14 emits blue light with a peak wavelength of 450nm.

[0027] The support substrate 15 is a flat plate-like substrate having a rectangular upper surface shape. The support substrate 15 is made of a material such as single crystal sapphire (Al2O3) that is semi-transparent to the blue light emitted from the semiconductor structure layer 14. The upper surface of the support substrate 15 is a light emitting surface from which the light emitting element 13 emits blue light.

[0028] The p-electrode 16 is an electrode electrically connected to the p-type semiconductor layer of the semiconductor structure layer 14. The p-electrode 16 is bonded to a p-side wiring (not shown) formed on the upper surface of the mounting substrate 12 via a conductive bonding member (not shown).

[0029] The n-electrode 17 is an electrode electrically connected to the n-type semiconductor layer via a through electrode (not shown) that penetrates the light emitting layer and the p-type semiconductor layer of the semiconductor structure layer 14 in the up-down direction and has a side surface covered with an insulator. In other words, the n-electrode 17 is electrically connected only to the n-type semiconductor layer and is insulated from the light emitting layer and the p-type semiconductor layer. The n-electrode 17 is bonded to an n-side wiring (not shown) formed on the upper surface of the mounting substrate 12 via a conductive bonding member (not shown).

[0030] As described above, the light emitting element 13 has a structure that emits blue light generated by applying a voltage to the p-electrode 16 and the n-electrode 17 via the mounting substrate 12 to cause a current to flow from the upper surface of the supporting substrate 15 through the semiconductor structure layer 14 .

[0031] [Phosphor component]

[0032] The phosphor member 18 is a phosphor plate bonded to the upper surface of the light emitting element 13 (i.e., the upper surface of the supporting substrate 15) via a translucent bonding member (not shown), and has a thickness of 50 μm to 250 μm and a rectangular upper surface shape. The phosphor member 18 has the same shape as the supporting substrate 15 of the light emitting element 13 in a top view.

[0033] The phosphor member 18 is made of phosphor excited by the blue light emitted from the light emitting element 13 to emit yellow fluorescence. Specifically, the phosphor member 18 is, for example, a single-phase transparent ceramic phosphor plate made of yttrium aluminum garnet phosphor (YAG:Ce) activated with cerium (Ce).

[0034] When the excitation light emitted from the light emitting surface of the light emitting element 13 is incident on the phosphor member 18, a portion of the excitation light directly passes through the phosphor member 18, and another portion of the excitation light excites the phosphor to cause the excited phosphor to emit yellow fluorescence. The yellow fluorescence emitted from the phosphor has a peak wavelength of 520nm to 570nm, and has a yellow emission spectrum with a broad peak of 480nm to 700nm.

[0035] Therefore, the excitation light (blue light) that has passed through the phosphor member 18 and does not contribute to the generation of fluorescence and the fluorescence (yellow light) emitted from the phosphor are emitted from the upper surface of the phosphor member 18. Therefore, white light in which the yellow fluorescence emitted from the upper surface of the phosphor member 18 and the blue light are mixed is extracted from the wavelength conversion device 100.

[0036] In the following instructions, Figure 1 As shown, a pair of side surfaces extending in the X direction in the drawing of the phosphor member 18 are defined as side surfaces 18X, and a pair of side surfaces extending in the Y direction in the drawing of the phosphor member 18 are defined as side surfaces 18Y.

[0037] The upper surface of the phosphor member 18 has an uneven structure including truncated cone-shaped protrusions 18C arranged at a pitch P in each of the X and Y directions in a matrix form and recessed portions 18G formed between the protrusions 18C in a square grid pattern.

[0038] The concave portion 18G of the uneven structure has a structure in which a plurality of grooves arranged in a plurality of vertical rows and a plurality of longitudinal rows are combined, and forms a grid-like structure that individually divides the protruding portion 18C. The pitch P is preferably 500 nm or less.

[0039] [Nanoantenna]

[0040] The nano-antennas 21 are a plurality of circular truncated cone-shaped metal materials formed on the respective upper surfaces of the protrusions 18C in the uneven structure of the phosphor member 18. Since the nano-antennas 21 are formed on the respective upper surfaces of the protrusions 18C arranged in a square grid pattern, similarly to the protrusions 18C, the nano-antennas 21 are arranged in a square grid pattern at a pitch P in a plan view.

[0041] Each lower surface of the nano-antenna 21 has the same size as each upper surface of the protrusion 18C of the phosphor member 18. In other words, the lower surface of the nano-antenna 21 and the upper surface of the protrusion 18C of the phosphor member 18 have the same diameter W as each other, and the protrusion 18C and the nano-antenna 21 formed on the upper surface of the protrusion 18C are combined to form a truncated cone as a whole.

[0042] The nanoantennas 21 have the same height H as each other on the respective upper surfaces of the protrusions 18C. Each nanoantenna 21 is configured of a material having a plasma frequency in the visible light region, such as Au (gold), Ag (silver), Cu (copper), Pt (platinum), Pd (palladium), Al (aluminum), and Ni (nickel), and an alloy or a laminate containing them. In particular, each nanoantenna 21 is preferably configured of a metal such as aluminum (Al) and copper (Ag) having low absorption in the visible light region.

[0043] Figure 1 and Figure 2 The uneven structure of the phosphor member 18 and the arrangement of the nano-antenna 21 are only schematically shown for the purpose of describing the uneven structure and the nano-antenna 21. In practice, the light emitting element 13 is, for example, 1 mm square, and in this case, the number of the protrusions 18C and the nano-antenna 21 to be formed is greater than Figure 1 and Figure 2 Quantity shown.

[0044] Here, the effect of enhancing the fluorescence provided by the nano-antenna 21 is described.

[0045] When the fluorescent light reaches the upper surface of the phosphor member 18 at an angle equal to or greater than the critical angle, the fluorescent light is totally reflected by the upper surface. When the total reflection occurs, an evanescent wave is generated that penetrates from the upper surface of the phosphor member 18 to the low refractive index medium side. The evanescent wave propagates along the upper surface of the phosphor member 18, in other words, along the interface between the phosphor member 18 and the air.

[0046] When reaching the nano-antenna 21, the evanescent wave propagating along the upper surface of the phosphor member 18 is radiated in the form of visible light having the same wavelength as the fluorescence in a direction satisfying the diffraction condition determined based on the arrangement pitch of the nano-antenna 21. This phenomenon causes the fluorescence to be emitted in a narrow angle range satisfying the diffraction condition, and promotes the narrowing of the angle of the fluorescence emitted from the upper surface of the phosphor member 18.

[0047] When the fluorescence emitted from the phosphor member 18 is irradiated on the nano-antenna 21, localized surface plasmon resonance occurs on the surface of the nano-antenna 21, and the electric field intensity near the nano-antenna 21 increases. Then, in a group of nano-antennas 21 arranged at a pitch P smaller than the peak wavelength of the fluorescence as described above, at a portion close to an adjacent nano-antenna 21, in other words, at a portion of an adjacent nano-antenna 21 facing the surface of each nano-antenna 21, the electric field intensity further increases.

[0048] Due to the highly localized plasma resonance as a result of the enhanced electric field, the fluorescence is greatly amplified near the nano-antenna 21, and the amplified fluorescence has a narrow angle (low light collection rate) light distribution characteristic. That is, the nano-antenna 21 has the function of enhancing the fluorescence emitted from the phosphor member 18 and narrowing the emission direction of the fluorescence.

[0049] [Light reflecting member]

[0050] The light reflecting member 22 is a member having light reflectivity, which continuously extends to cover the semiconductor structure layer 14 and the supporting substrate 15 of the light emitting element 13 and the corresponding outer surfaces of the phosphor member 18. The light reflecting member 22 is configured of a translucent resin containing light scattering particles, and is made of, for example, a resin material in which titanium oxide (TiO2) particles are contained in a silicone resin.

[0051] The light reflecting member 22 reflects, for example, excitation light (blue light) emitted from the light emitting element 13 and reaching upward to the outer surface. The light reflecting member 22 reflects, for example, fluorescent light generated in the phosphor member 18 and reaching upward to the outer surface.

[0052] As described above, the plurality of recessed portions and the plurality of protruding portions formed on the upper surface of the phosphor member 18 are arranged at a pitch P smaller than the peak wavelength of the fluorescence emitted from the phosphor member 18. In other words, the phosphor member 18 has an uneven structure including the plurality of protruding portions disposed at a pitch smaller than the peak wavelength of the fluorescence at the upper surface.

[0053] According to this embodiment, since the spacing P in the uneven structure at the surface of the phosphor member 18 is smaller than the peak wavelength of the fluorescence, when the fluorescence reaches the uneven structure, the behavior of the fluorescence is similar to the case where the refractive index of the medium gradually changes in the height direction of the uneven structure portion, specifically, the case where the refractive index becomes low and approaches the refractive index of air toward the upper side.

[0054] Therefore, compared with the case where there is no uneven structure, the critical angle of fluorescence to the interface between the phosphor member 18 and the air at the upper surface of the phosphor member 18 is larger, and total reflection is less likely to occur. Therefore, the component equal to or greater than the critical angle of fluorescence of the phosphor member 18 can be reduced, and the component totally reflected by the interface between the phosphor member 18 and the air can be reduced.

[0055] Therefore, according to this embodiment, it is possible to increase the ratio of fluorescence extracted from each upper surface of the protruding portion 18C of the phosphor member 18. That is, it is possible to improve light extraction efficiency while achieving a narrow angle of fluorescence using the nano-antenna 21.

[0056] [Method for manufacturing phosphor member]

[0057] A method for manufacturing the phosphor member 18 having an uneven structure and including the nano-antenna 21 formed on the upper surface of the protruding portion 18C of the uneven structure is described below.

[0058] First, a metal film of Al or Ag as a base material of the nanoantenna 21 is formed on the upper surface of a flat plate-shaped base material as the phosphor member 18 by electron beam evaporation or sputtering film formation (step 1).

[0059] Next, a resist is applied over the metal film formed in step 1, and patterning is performed using a nanoimprint apparatus or an ion beam drawing apparatus to form uneven portions in a square grid pattern (step 2).

[0060] Next, by using the resist applied over the member to be the protruding portion of the uneven portion patterned in step 2 as an etching mask, dry etching of the member to be the recessed portion is performed (step 3). At this time, by performing etching until the depth of the recessed portion becomes a depth D, an uneven structure including a recessed portion 18G having a depth D is obtained.

[0061] Finally, the etching mask (resist) of the part to be the protruding portion is removed by ashing (step 4). Thus, the phosphor member 18 having an uneven structure on the upper surface and including the nanoantenna 21 formed on the corresponding upper surface of the protruding portion 18C of the uneven structure can be obtained.

[0062] When the uneven structure of the phosphor member 18 and the nano-antenna 21 are formed by the above-mentioned etching, the type of etching gas can be appropriately selected corresponding to the etching target. For example, when the nano-antenna 21 made of Al is formed, etching is performed using chlorine (Cl2) gas and argon (Ar) gas. For example, when an uneven structure is formed on a phosphor plate made of YAG:CEe phosphor, etching is performed using sulfur hexafluoride (SF6) gas, tetrafluorinated methane (CF4) gas, etc.

[0063] [verify]

[0064] Refer to the following Figures 3 to 6 Verification performed on the wavelength conversion device 100 of the present invention and its verification results are described. In the verification, the depth D of the concave portion 18G in the uneven structure of the phosphor member 18 was mainly verified.

[0065] The model used in the verification is described. The phosphor member 18 is a YAG:Ce phosphor single-phase single crystal ceramic plate, and the nanoantenna 21 is made of Al. In the uneven structure of the phosphor member 18, the pitch P of the above-mentioned uneven part is 350nm, and the arrangement aspect is a square grid arrangement. The nanoantenna 21 has a height H of 150nm and a lower surface diameter W of 200nm (the diameter of the upper surface of the protrusion 18C). The incident light from the phosphor member 18 incident on the nanoantenna 21 has a wavelength of 550nm (the peak wavelength of yellow fluorescence).

[0066] Figure 3 is a graph showing the result of calculating the intensity of fluorescence extracted in the air via the nanoantenna 21 (through the surface on which the nanoantenna 21 is formed) using the RCWA (rigorous coupled wave analysis) method when the incident angle of the fluorescence to the interface between the phosphor member 18 and the air is changed.

[0067] Figure 3 The transmission intensity of fluorescence when the depth D of the recessed portion 18G is 0 nm (no uneven structure), 10 nm, 30 nm, 50 nm, 70 nm, and 100 nm is shown. Figure 3 The critical angle of the incident angle at the interface between the phosphor member 18 and the air in the absence of the nano-antenna and the uneven structure (the case where the depth D is 0 nm) is also shown by a two-dot chain line. In this embodiment, the critical angle is 34 degrees.

[0068] from Figure 3 It can be seen that when the incident angle of fluorescence is in the range of 20° to 65°, the transmission intensity at the depth D of the recessed portion 18G at 10 nm, 30 nm, 50 nm, 70 nm, and 100 nm is high compared to the case without the recessed portion (D=0 nm). In particular, in the range of the fluorescence incident angle from 20° to the critical angle in the case without the nanoantenna and the uneven structure (the double-dashed line in the figure), it is significantly shown that the transmission intensity becomes higher in the case where the recessed portion 18G is included in the phosphor member 18 than in the case without the recessed portion.

[0069] Furthermore, it can be seen that within the range of the fluorescence incident angle of 20° to 65°, the transmission intensity increases with the increase in the depth D of the recessed portion 18G. Therefore, by providing a plurality of recessed portions including the recessed portion 18G having the depth D and a plurality of protruding portions at the phosphor member 18, high light extraction efficiency can be provided within a wide range of fluorescence incident angles.

[0070] Figure 4 is a graph showing the calculation results of the transmission intensity using the RCWA method when the depth D of the recessed portion 18G is changed. Figure 4 In the case where the incident angle of the fluorescence is the full angle range, the case where the incident angle of the fluorescence reaches a critical angle less than the case where there is no nanoantenna and the uneven structure, and the case where the incident angle of the fluorescence is equal to or greater than the critical angle of the case where there is no nanoantenna and the uneven structure, the transmission intensity is calculated in each of the following cases. Figure 4 , the transmission intensity without the recessed portion 18G is represented as 1.0.

[0071] according to Figure 4 , when the depth D of the recessed portion 18G is in the range of 10 nm to 100 nm, the transmission intensity is increased by about 10% to 20% in each range of the fluorescent light incident angle as compared with the case without the recessed portion 18G.

[0072] When the depth D of the recessed portion 18G exceeds 120 nm, the fluorescence transmission intensity at a critical angle equal to or greater than the case where there is no nanoantenna and the uneven structure is lower than the transmission intensity in the case where there is no recessed portion 18G. That is, it can be seen that in order to keep the fluorescence transmission intensity in a range equal to or greater than the critical angle where there is no nanoantenna and the uneven structure higher than the transmission intensity in the case where there is no recessed portion 18G, the depth D of the recessed portion 18G is preferably 120 nm or less.

[0073] Figure 5 : is a graph showing the result of calculating the transmission intensity using the RCWA method when the incident angle of the fluorescent light is in the full angle range when the depth D of the concave portion 18G is changed. Figure 5 In , the wavelength conversion device 100 and a wavelength conversion device having a configuration without a nano-antenna are used as comparison targets to verify the change in transmission intensity depending on whether the nano-antenna is provided. Figure 5 , in each model including / excluding the nano-antenna, the transmission intensity without the recessed portion 18G is indicated as 1.0.

[0074] according to Figure 5, the transmission intensity without the nano-antenna increases as the depth D of the recessed portion 18G increases. That is, in order to increase the transmission intensity of the fluorescent light emitted from the phosphor member 18 having the uneven structure, increasing the depth D of the recessed portion 18G is preferred.

[0075] However, as described above, when the nanoantenna 21 is formed on the upper surface of the protrusion 18C (including the nanoantenna), when the depth D of the recessed portion 18G exceeds 120 nm, the fluorescence transmission intensity within the incident angle range equal to or greater than the critical angle of the case without the nanoantenna and the uneven structure becomes lower than that in the case without the nanoantenna and the uneven structure.

[0076] Therefore, in order to improve the efficiency of extracting light from the phosphor member 18 while using fluorescence having an incident angle equal to or greater than the critical angle without the nanoantenna and the uneven structure, the depth D of the recessed portion 18G is preferably 120 nm or less.

[0077] Figure 6 is a graph showing the penetration length of the evanescent wave penetrating from the upper surface of the phosphor member 18 when the intensity changes from the maximum intensity to the predetermined intensity with respect to the changed fluorescent light incident angle.

[0078] Figure 6 The penetration length of the evanescent wave generated at the surface of the phosphor member when the intensity changes from the maximum intensity to the intensity of 1 / e for each wavelength of fluorescence (500nm, 550nm, 600nm, 650nm) is shown. The penetration length d of the evanescent wave is obtained by the following formula.

[0079] [Mathematical formula 1]

[0080]

[0081] Here, wavelength λ is the wavelength of the fluorescence, refractive index n1 is the refractive index of the phosphor member 18, and refractive index n2 is the refractive index of air. Incident angle θ is the incident angle of the fluorescence to the interface between the phosphor member 18 and air.

[0082] according to Figure 6 , within the range of the fluorescence incident angle up to 40°, the variation of the penetration length d with respect to the incident angle is large, and within the range of the fluorescence incident angle from 40° to 89°, the variation of the penetration length d with respect to the incident angle is small.

[0083] For example, when the wavelength of fluorescence is 550 nm, in order to obtain an evanescent wave with a penetration length d of 150 nm, fluorescence of a component with a fluorescence incident angle θ less than 40° is required. In other words, when the fluorescence incident angle θ exceeds 40°, it is unlikely to obtain an evanescent wave with a penetration length d of 150 nm.

[0084] That is, as the depth D of the recessed portion 18G becomes deeper, an evanescent wave having a penetration length d corresponding to the depth is required, and therefore, the range of the fluorescence incident angle that satisfies the penetration length d is limited.

[0085] Therefore, in Figure 5 In FIG. 1 , it is considered that when the depth D of the recessed portion 18G is deepened, the evanescent wave becomes difficult to penetrate to reach the nano-antenna 21 , and this causes the electric field to be less likely to be enhanced, thereby reducing the transmission intensity of the fluorescence.

[0086] Therefore, according to Figures 3 to 6 As shown in the results, in order to improve the light extraction efficiency while using a wide range of fluorescent incident angles, the depth D of the concave portion 18G in the uneven structure of the phosphor member 18 is preferably 120nm or less. That is, the height of the protrusion 18C from the bottom surface of the concave portion 18G is preferably 120nm or less.

[0087] [Modifications]

[0088] Refer to the following Figure 7 A modification example of the wavelength conversion device 100 according to the first embodiment is described. Figure 7 1 is a top view of a wavelength conversion device 110 according to a modification. The wavelength conversion device 110 according to the modification is different from the first embodiment in the formation of the uneven structure of the phosphor member 18, and is similar to the first embodiment in other aspects, for example, in the configuration of the light emitting element 13 and the arrangement pitch of the nano-antenna 21.

[0089] In this modification, the phosphor member 18 has an uneven structure including a plurality of recessed portions and a plurality of protruding portions extending from one side 18X to the other side 18X in the direction of the side 18Y in a plan view. That is, the uneven structure of the phosphor member 18 forms a stripe pattern in which a plurality of protruding portions 18C and a plurality of recessed portions 18G are provided in the direction along the side 18Y.

[0090] In this modification, the respective nano-antennas 21 are arranged on the respective upper surfaces of the protruding portion 18C at the same pitch P as each other along the extending direction of the protruding portion 18C.

[0091] The wavelength conversion device 110 having such a configuration can also provide effects similar to those of the first embodiment. That is, components equal to or greater than the critical angle of fluorescence of the phosphor member 18 can be reduced, and components totally reflected by the interface between the phosphor member 18 and air can be reduced.

[0092] Therefore, it is possible to increase the ratio of fluorescent light extracted from the phosphor member 18. Therefore, it is possible to improve light extraction efficiency while achieving a narrow angle of fluorescent light using the nano-antenna 21.

[0093] Second embodiment

[0094] Next, refer to Figure 8 A second embodiment will be described. Figure 8 2 is a cross-sectional view of a wavelength conversion device 200 according to a second embodiment. The wavelength conversion device 200 is different from the first embodiment in that a translucent member 24 is provided, and is similar to the first embodiment in other aspects, for example, in the configuration of the light emitting element 13 and the formation of the uneven structure of the phosphor member 18.

[0095] like Figure 8 As shown, the translucent member 24 is a member that fills the recessed portion 18G up to a height approximately consistent with the upper surface of the protruding portion 18C in the uneven structure of the phosphor member 18. In other words, the translucent member 24 fills the recessed portion 18G in a manner that exposes the corresponding upper surface of the protruding portion 18C in the uneven structure.

[0096] The translucent member 24 is made of a material that is translucent to the emission light (blue light) from the light emitting element 13 and the fluorescence (yellow light) generated in the phosphor member 18 and has a refractive index smaller than that of the phosphor member 18. The translucent member 24 is made of, for example, silicon dioxide (SiO2 (refractive index n=1.46)) or Al2O3 (refractive index n=1.63).

[0097] According to this embodiment, since the translucent member 24 having a refractive index smaller than that of the phosphor member 18 is filled in the concave portion 18G of the phosphor member 18 , the behavior of the refractive index change when the fluorescent light reaches the uneven structure becomes more gentle.

[0098] That is, compared with the first embodiment, by filling the translucent member 24 in the concave portion 18G of the phosphor member 18, the critical angle of fluorescence to the interface between the phosphor member 18 and the air at the upper surface of the phosphor member 18 becomes larger, resulting in less likely total reflection. Therefore, compared with the first embodiment, the component equal to or greater than the critical angle of fluorescence of the phosphor member 18 can be reduced, and the component totally reflected by the interface between the phosphor member 18 and the air can be reduced.

[0099] Therefore, according to this embodiment, it is possible to increase the ratio of fluorescence extracted from each upper surface of the protruding portion 18C of the phosphor member 18. That is, it is possible to improve light extraction efficiency while achieving a narrow angle of fluorescence using the nano-antenna 21.

[0100] The translucent member 24 is preferably filled in the recessed portion 18G to a height that is not in direct contact with the nano-antenna 21. This is because the translucent member 24 in contact with the nano-antenna 21 reduces the sensitivity of the nano-antenna 21 to the evanescent wave, thereby reducing the effect of enhancing fluorescence. Therefore, the translucent member 24 is preferably filled in the recessed portion 18G, for example, to be lower than the upper surface of the protruding portion 18C by a predetermined height.

[0101] [Method for manufacturing phosphor member]

[0102] Here, a method for manufacturing the phosphor member 18 in which the translucent member 24 is formed according to the second embodiment is described. Since the process before the step of forming a recessed portion at the phosphor member by etching (step 3) is similar to the first embodiment, the description thereof is omitted.

[0103] First, on the uneven structure of the phosphor member formed by patterning similar to the first embodiment, a transparent dielectric film made of SiO2 or Al2O3 is formed by electron beam evaporation or sputtering film formation (step 4A). Thus, a translucent member is formed over the upper surface of the phosphor member.

[0104] Next, the translucent member formed on the etching mask (resist) of the corresponding protruding portion 18C is removed together with the etching mask by a lift-off process (step 5). Thus, the phosphor member 18 in which the translucent member 24 is filled in the recessed portion 18G can be obtained.

[0105] The above configuration in which the semi-transparent member 24 is filled in the recessed portion 18G can be applied to the configuration of the above-described modification. That is, a configuration in which the semi-transparent member 24 is filled in each of the plurality of recessed portions 18G formed in a stripe pattern can be applied.

[0106] Third embodiment

[0107] Next, refer to Fig. 9 and Fig.10 A third embodiment is described. Fig. 9 is a cross-sectional view schematically showing the configuration of a lighting device 300 according to the third embodiment. Fig.10 is a cross-sectional view of the wavelength conversion device 310. Fig. 9 In the example above, shadows are omitted for visibility reasons.

[0108] The housing 26 is a box-shaped housing provided with openings OP1 and OP2 at respective two surfaces facing each other. The housing 26 is provided with a support structure 26A for supporting an object at a position between the openings OP1 and OP2. The support structure 26A is provided with a through hole 26AO penetrating the support structure 26A at its center.

[0109] The light source 27 is a light source that is fixed in the opening OP1 and emits light L1 having a predetermined wavelength toward the opening OP2. The opening OP1, the through hole 26AO, and the opening OP2 are formed on the optical axis OA.

[0110] In this embodiment, the light source 27 is a laser light source having a light emitting layer made of an InGaN-based semiconductor. The light source 27 emits blue light having a peak wavelength of about 450 nm as the light L1.

[0111] The wavelength conversion device 310 is supported by the support structure 26A located on the optical axis OA. Specifically, the wavelength conversion device 310 is disposed on the upper surface of the support structure 26A in such a manner that the central portion of the bottom surface through which the optical axis OA passes is exposed from the through hole 26AO of the support structure 26A. In other words, in the wavelength conversion device 310, the area other than the center of the bottom surface of the wavelength conversion device 310 is supported by the support structure 26A.

[0112] like Fig.10 As shown, the wavelength conversion device 310 includes Figure 2 The phosphor member 18 shown, the nano-antennas 21 formed on the respective upper surfaces of the protruding portions 18C of the phosphor member 18, and the light reflecting member 22 formed on the side surfaces of the phosphor member 18. In other words, the wavelength conversion device 310 has a configuration in which the mounting substrate 12 and the light emitting element 13 are removed from the configuration of the wavelength conversion device 100 in the first embodiment.

[0113] Similar to the first embodiment, the wavelength conversion device 310 is excited by the excitation light (blue light) having a peak wavelength of 450 nm to emit fluorescence (yellow light) having a peak wavelength of 550 nm. Therefore, the wavelength conversion device 310 emits the excitation light (blue light) that has passed through the phosphor member 18 and does not contribute to the generation of fluorescence, and the fluorescence (yellow light) emitted from the phosphor. Fig. 9 The excitation light and the fluorescence emitted from the wavelength conversion device 310 are shown together as the light L2.

[0114] A transparent support substrate having high thermal conductivity made of, for example, single crystal sapphire may be provided between the wavelength conversion device 310 and the support structure 26A. Providing the transparent support substrate allows heat generated at the wavelength conversion device 310 to be efficiently transferred to the support structure 26A.

[0115] A lens that collects laser light may be provided between the light source 27 and the incident plane of the light L1 of the wavelength conversion device 310. Providing the lens allows the laser light to be collected to effectively irradiate the wavelength conversion device 310 with the laser light.

[0116] The lens 28 is an optical member fixed in the opening OP2. That is, the lens 28 is located on the optical axis OA. The lens 28 is an optical lens that receives the light L2 emitted from the wavelength conversion device 310 and forms the light L2 in a desired light distribution to generate light L3 as illumination light. For example, a spherical lens and an aspherical lens can be used for the lens 28. The light L3 generated by the lens 28 is extracted to the outside of the housing 26.

[0117] In this embodiment, the space between the light source 27 and the wavelength conversion device 310 in the housing 26 and the space between the wavelength conversion device 310 and the lens 28 are filled with air. That is, the light L2 emitted from the wavelength conversion device 310 is incident on the lens 28 through the air.

[0118] The lighting device 300 having the above configuration can also provide effects similar to those of the first embodiment. That is, components equal to or greater than the critical angle of fluorescence of the phosphor member 18 can be reduced, and components totally reflected by the interface between the phosphor member 18 and air can be reduced.

[0119] Therefore, it is possible to increase the ratio of fluorescent light extracted from the phosphor member 18. Therefore, it is possible to improve light extraction efficiency while achieving a narrow angle of fluorescent light using the nano-antenna 21.

[0120] Although the case where the phosphor member 18 is made of a single crystal YAG:Ce phosphor plate is described in the above-mentioned embodiment and the modified example, the configuration of the phosphor member 18 is not limited thereto, and the phosphor member 18 only needs to have a configuration in which light scattering is less likely to occur inside. As a configuration in which scattering is less likely to occur, a single-phase phosphor plate made of a single material is preferred, and in this case, polycrystalline can be used. For example, a plate having a resin or glass medium containing phosphor particles emitting yellow fluorescence can be used.

[0121] Although the above-mentioned embodiment and modification examples describe the case where the corresponding protrusions 18C in the uneven structure of the phosphor member 18 are arranged in a square grid pattern on the upper surface of the phosphor member 18, it is not limited thereto. For example, the corresponding protrusions 18C may be arranged in a triangular grid pattern on the upper surface of the phosphor member 18.

[0122] Although the case where the nano-antenna 21 has a truncated cone shape is described in the above-mentioned embodiments and modifications, the shape is not limited thereto, and it is only necessary that the nano-antenna 21 provides an action of narrowing the angle of fluorescence. For example, the nano-antenna 21 may have a columnar shape (such as a column) or a conical shape (such as a cone).

[0123] Although the case where the light reflecting member 22 is provided is described in the above-mentioned embodiment and the modification example, depending on the required light distribution, it is not necessary to provide the light reflecting member 22. Depending on the required light distribution, an optical multilayer reflective film or a metal reflective film may be used instead of the light reflecting member 22, or a combination thereof may be provided on the side surfaces of the light emitting element 13 and the phosphor member 18.

[0124] Description of Reference Numerals

[0125] 100, 110, 200, 310: wavelength conversion device

[0126] 300: Lighting device

[0127] 12: Install the base plate

[0128] 13: Light-emitting element

[0129] 14: Semiconductor structure layer

[0130] 15: Support substrate

[0131] 16: p electrode

[0132] 17: n electrode

[0133] 18: Phosphor component

[0134] 21: Nanoantenna

[0135] 22: Light reflecting member

[0136] 24: Translucent components

[0137] 26: Shell

[0138] 27: Light source (laser light source)

[0139] 28: Lens

Claims

1. A wavelength conversion device, comprising: a phosphor member having one surface on which excitation light is incident, the phosphor member including a phosphor excited by the excitation light to emit fluorescence, and having an uneven structure on another surface on an opposite side of the one surface, the uneven structure including a plurality of protrusions, each of the protrusions being arranged in one direction along the other surface at a pitch smaller than a peak wavelength of the fluorescence; as well as A plurality of nano-antennas are disposed at upper surfaces of the plurality of protrusions and are made of a metal material.

2. The wavelength conversion device according to claim 1, wherein: The uneven structures form an arrangement pattern of a square grid pattern or a triangle grid pattern, and The plurality of nano-antennas are disposed on corresponding upper surfaces of the plurality of protrusion portions.

3. The wavelength conversion device according to claim 1, wherein: The uneven structure forms a stripe pattern arranged along the one direction, and The plurality of nano-antennas are arranged at corresponding ones of the plurality of protrusions along an extension direction of the plurality of protrusions.

4. The wavelength conversion device according to claim 1, comprising: A translucent member fills the concave portion of the uneven structure, the translucent member having a smaller refractive index than the phosphor member and having translucency to the excitation light and the fluorescent light.

5. The wavelength conversion device according to claim 1, wherein: The phosphor has a characteristic of being excited by the excitation light to emit fluorescence with a peak wavelength of 520 nm to 570 nm, and Each of the plurality of protruding portions has a height of 120 nm or less.

6. The wavelength conversion device according to claim 1, wherein: The phosphor member is made of a single-phase phosphor plate.

7. The wavelength conversion device according to claim 1, wherein: The plurality of nano-antennas are formed in a cylindrical shape, a conical shape or a truncated conical shape.

8. The wavelength conversion device according to claim 1, wherein: The plurality of nano-antennas are made of Al or Ag.

9. A lighting device, comprising: The wavelength conversion device according to claim 1; as well as A light source emits the excitation light toward the one surface of the phosphor member.

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