Optical element and light-emitting element

Abstract

To provide an optical element and a light-emitting element capable of improving extraction efficiency of emission light.SOLUTION: A light-emitting device includes a light-transmissive substrate having a rectangular shape in a top view and translucency, a polarizing element that is formed on an upper surface of the light-transmissive substrate and transmits a polarized component vibrating in one direction along one side of the upper surface of the light-transmissive substrate, and an optical film that is formed on at least one surface of a side surface of the light-transmissive substrate and transmits a polarized component vibrating in the one direction and reflects a polarized component vibrating in another direction orthogonal to the one direction in a top view.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an optical element and a light-emitting device including the optical element. [Background technology]

[0002] Light-emitting devices having a polarizing layer that transmits specific light have been disclosed. For example, Patent Document 1 discloses a light-emitting device including a light-emitting element (LED die), a phosphor layer formed on one main surface of the light-emitting element, a light polarizing layer made of a wire grid formed on the phosphor layer, and a light-reflecting layer formed on the other main surface of the light-emitting element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2011-501460 Summary of the Invention [Problem to be solved by the invention]

[0004] In the light emitting device described in Patent Document 1, of the light that reaches the light polarization layer, the polarized component having a vibration direction perpendicular to the longitudinal direction of the wire grid is transmitted through the light polarization layer, while the polarized component parallel to the longitudinal direction is reflected by the light polarization layer. Furthermore, even if the polarized component has a vibration direction perpendicular to the longitudinal direction of the wire grid, the component that enters the light polarization layer from the phosphor layer at an angle exceeding the critical angle is totally reflected.

[0005] In the light-emitting device described in Patent Document 1, for example, the component reflected by the light polarizing layer as described above may be reflected by the light reflecting layer and enter the light polarizing layer again. However, even when light is reflected by the light polarizing layer, a portion of the light is absorbed by the metal material that makes up the light polarizing layer, and therefore, the more light is reflected between the light polarizing layer and the light reflecting layer, the more the light extraction efficiency of the light-emitting device as a whole may decrease.

[0006] The present invention has been made in view of the above-mentioned points, and has an object to provide an optical element and a light-emitting element that can improve the extraction efficiency of emitted light. [Means for solving the problem]

[0007] The optical element according to the present invention is characterized by comprising: a light-transmitting substrate having a rectangular, flat top surface and light-transmitting properties; a polarizing element formed on the top surface of the light-transmitting substrate and transmitting polarized light components vibrating in one direction along one side of the top surface of the light-transmitting substrate; and an optical film formed on at least one of the side surfaces of the light-transmitting substrate and transmitting polarized light components vibrating in one direction and reflecting polarized light components vibrating in another direction perpendicular to the one direction in a top view.

[0008] Furthermore, the light-emitting element according to the present invention is characterized by comprising: a light-emitting element portion including a semiconductor structure layer having a light-emitting layer; a phosphor layer formed on the light-emitting element portion and including a phosphor that is excited by light emitted from the light-emitting layer to emit fluorescence; a light-reflecting film formed on side surfaces of the light-emitting element portion and the phosphor layer and having light-reflecting properties; a light-transmitting substrate formed on the phosphor layer, having a rectangular flat top surface shape and having light-transmitting properties; a polarizing element formed on the top surface of the light-transmitting substrate and transmitting polarized components vibrating in one direction along one side of the top surface of the light-transmitting substrate; and an optical film formed on at least one side surface of the light-transmitting substrate and transmitting polarized components vibrating in one direction and reflecting polarized components vibrating in another direction perpendicular to the first direction in a top view. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a top view of a light emitting element according to an example. [Figure 2] FIG. 2 is a cross-sectional view of a light-emitting element according to an example. [Figure 3] FIG. 10 is a cross-sectional view showing a model for verifying the light-emitting element according to the example. [Figure 4] 10 is a table showing luminous fluxes when simulating light emitted from each model. [Figure 5] 1A to 1C are perspective views showing an example of a manufacturing process of a light emitting element according to an example. [Figure 6] 1A to 1C are perspective views showing an example of a manufacturing process of a light emitting element according to an example. [Figure 7] 1A to 1C are perspective views showing an example of a manufacturing process of a light emitting element according to an example. [Figure 8] 1A to 1C are perspective views showing an example of a manufacturing process of a light emitting element according to an example. [Figure 9] 10A to 10C are perspective views showing another example of the manufacturing process of the light emitting element according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description and accompanying drawings, substantially the same or equivalent parts are designated by the same reference numerals. [Example]

[0011] [Outline of the light-emitting element 100] The configuration of a light-emitting device 100 according to Example 1 will be described with reference to Figures 1 and 2. Figure 1 is a top view of the light-emitting device 100 according to Example 1. Figure 2 is a cross-sectional view of the light-emitting device 100 taken along line 2-2 shown in Figure 1.

[0012] 1 and 2, the light-emitting element 100 includes a light-emitting element section 11, a phosphor layer 13, a light-transmitting substrate 15, a wire grid 17, an optical film 19, and a frame section 21. In FIG. 2, the vertical direction in the drawing corresponds to the height direction of the light-emitting element 100, and the horizontal direction in the drawing corresponds to the width direction of the light-emitting element 100.

[0013] [Light-emitting element part 11] First, the configuration of the light-emitting element section 11 will be described. The light-emitting element section 11 is a light-emitting diode (LED) having a rectangular top surface shape. The light-emitting element section 11 includes a semiconductor structure layer 23 and a support substrate 24. In the light-emitting element 100 of this example, the light-emitting element section 11 has a size of 1 mm square.

[0014] The semiconductor structure layer 23 is a semiconductor laminate consisting of an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer (none of which are shown), each of which is made primarily of gallium nitride (GaN). When the light-emitting element 100 is driven, blue light having a peak wavelength of approximately 450 nm is emitted from the light-emitting layer of the semiconductor structure layer 23.

[0015] The support substrate 24 is a flat substrate provided on the semiconductor structure layer 23. The support substrate 24 is made of a material such as sapphire (Al2O3) or gallium nitride (GaN) that is transparent to the blue light emitted from the light emitting layer of the semiconductor structure layer 23. The support substrate 24 also serves as a growth substrate for growing semiconductor crystals that will become the semiconductor structure layer 23 described above.

[0016] [Phosphor layer 13] Next, the phosphor layer 13 will be described. The phosphor layer 13 is a plate-like body with a rectangular upper surface that is provided on the upper surface of the support substrate 24 of the light-emitting element portion 11. The phosphor layer 13 has the same size as the light-emitting element portion 11 when viewed from above the light-emitting element 100.

[0017] The phosphor layer 13 is made of a phosphor that emits fluorescence when excited by blue light as excitation light emitted from the light-emitting element section 11. The fluorescence emitted from the phosphor when excited by blue light has a broad green to orange wavelength range spanning 480 to 700 nm, and has a yellow peak wavelength at 520 to 570 nm.

[0018] The phosphor layer 13 is formed by dispersing particles of a yttrium aluminum garnet (YAG:Ce) phosphor using cerium (Ce) as an activator in a light-transmitting resin such as a silicone resin. In the light-emitting element 100 of this embodiment, the phosphor layer 13 has a thickness of 100 μm.

[0019] The phosphor layer 13 may be a ceramic phosphor plate made of a medium of alumina (Al2O3) or silicon dioxide (SiO2) containing YAG:Ce phosphor particles, instead of a translucent resin containing YAG:Ce phosphor particles.

[0020] When excitation light (blue light) emitted from the light-emitting element section 11 is incident on the phosphor layer 13, part of the light passes through the phosphor layer 13 as is, and part of the light excites the phosphors, causing the excited phosphors to emit fluorescence. Therefore, the excitation light that passed through the phosphor layer 13 without contributing to the generation of fluorescence and the fluorescence emitted from the phosphors are emitted from the upper surface of the phosphor layer 13.

[0021] A reflective film 26 is formed on the side surfaces of the light emitting element section 11 and the phosphor layer 13, continuously covering the side surfaces. The reflective film 26 is a reflective film that is reflective to light components that are incident on the reflective film 26 at an incident angle within a critical angle. In the configuration shown in FIG. 2 , light components that are incident on the reflective film 26 at an incident angle exceeding the critical angle are totally reflected by the side surfaces of the light emitting element section 11 and the phosphor layer 13 before reaching the reflective film 26.

[0022] The reflective film 26 is a dielectric multilayer film in which a dielectric material with a low refractive index and a dielectric material with a high refractive index are alternately laminated. In the light-emitting element 100 of this embodiment, the reflective film 26 is formed by alternately laminating a total of 48 layers of silicon oxide (SiO2) as a dielectric material with a low refractive index and titanium oxide (TiO2) as a dielectric material with a high refractive index so as to have a layer thickness that reflects light in the wavelength ranges of excitation light (blue light) and fluorescence (yellow light). In other words, the reflective film 26 is formed by laminating 24 pairs of layers, each consisting of one SiO2 layer and one TiO2 layer.

[0023] In addition to the above-mentioned materials, the reflective film 26 may be made of alumina (Al2O3) as a low refractive index dielectric material, or zirconium oxide (ZrO2), niobium pentoxide (Nb2O5), lanthanum oxide (La2O3), tantalum pentoxide (Ta2O5), or hafnium oxide (HfO2) as a high refractive index dielectric material.

[0024] [Transparent substrate 15] Next, we will explain the light-transmitting substrate 15. The light-transmitting substrate 15 is provided on the upper surface of the phosphor layer 13 and is a plate-like body with a rectangular upper surface shape. The light-transmitting substrate 15 is made of a material that is transparent to the above-mentioned excitation light and fluorescence, such as glass.

[0025] In the light-emitting element 100 of this embodiment, the thickness of the light-transmitting substrate 15 is 700 μm. Hereinafter, in a top view of the light-emitting element 100, a pair of widthwise sides of the light-transmitting substrate 15 will be referred to as sides 15A, and a pair of front-rear sides will be referred to as sides 15B.

[0026] [Wire Grid 17] Next, we will explain the wire grid 17. The wire grid 17 is a structure in which a plurality of linear metal bodies 17A are formed in rows along the sides 15B on the upper surface of the light-transmitting substrate 15. Note that the number of metal bodies 17A in Figures 1 and 2 is merely shown schematically, and in reality, more metal bodies than shown are formed.

[0027] 1, metal bodies 17A constituting wire grid 17 extend from one side 15B to the other along side 15A of light-transmitting substrate 15. Metal bodies 17A are made of a metal with high light reflectance and corrosion resistance, such as aluminum (Al).

[0028] In the light-emitting element 100 of this embodiment, the arrangement period of the metal bodies 17A formed on the upper surface of the light-transmitting substrate 15 is set to a period shorter than the wavelengths of the excitation light (blue light) and the fluorescence (yellow light), for example, 150 nm. In the light-emitting element 100 of this embodiment, the width of each of the metal bodies 17A is set to 60 nm, and the height of each of the metal bodies 17A is set to 165 nm.

[0029] By setting the arrangement period of metal bodies 17A as described above, of the blue light and yellow light, the P-polarized components, which are polarization components whose vibration direction is perpendicular to the longitudinal direction of metal bodies 17A, are transmitted through wire grid 17, and the S-polarized components, which are polarization components parallel to the longitudinal direction, are reflected by wire grid 17. In other words, wire grid 17 functions as a polarizing element that transmits only light that vibrates in a specific direction and reflects light that vibrates in other directions.

[0030] The wire grid 17 can be formed, for example, by forming a metal film made of Al on the entire upper surface of the light-transmitting substrate 15 by ion beam deposition, forming a resist mask on the upper surface of the area that will become the metal body 17A, and then removing the metal film in the area not covered by the resist mask by dry etching.

[0031] [Optical film 19] Next, we will explain the optical film 19. As shown in Fig. 1 , the optical film 19 has first optical films 19A formed on two side surfaces of the light-transmitting substrate 15, including the side 15A, and second optical films 19B formed on two side surfaces of the light-transmitting substrate 15, including the side 15B.

[0032] In the following explanation, for convenience of explanation, even when describing the side surface of the light-transmitting substrate 15, a polarization component whose vibration direction in a plane parallel to the top surface of the light-transmitting substrate 15 is perpendicular to the longitudinal direction of the metal body 17A of the wire grid 17 will be referred to as a P-polarization component, and a polarization component parallel to the longitudinal direction of the metal body 17A will be referred to as an S-polarization component.

[0033] The first optical film 19A and the second optical film 19B are so-called polarization beam splitter (PBS) films that transmit polarized components of light incident thereon in a specific vibration direction and reflect polarized components of vibration directions other than the specific vibration direction.

[0034] When viewed from a direction perpendicular to the side surface including side 15A of light-transmitting substrate 15, first optical film 19A transmits P-polarized light components, which are polarization components whose vibration direction is perpendicular to the side surface, and reflects S-polarized light components, which are polarization components whose vibration direction is parallel to side 15A. That is, the light transmitted through first optical film 19A has the same vibration direction as the light transmitted through wire grid 17 when viewed from above.

[0035] The first optical film 19A is made of a dielectric multilayer film whose thickness is adjusted so as to transmit the P-polarized component and reflect the S-polarized component of light incident on the first optical film 19A. In the light emitting element 100 of this embodiment, the first optical film 19A is made of 40 to 50 layers in total, each layer being made of SiO2 as a low refractive index dielectric material and TiO2 as a high refractive index dielectric material, which are alternately stacked.

[0036] The first optical film 19A is configured to transmit the P polarized component incident within a predetermined range of incident angles (for example, 35° to 41.5°) and to reflect the P polarized component incident at an incident angle outside this range.

[0037] In addition to the materials mentioned above, the first optical film 19A may be made of Al2O3 as a low refractive index dielectric material, or ZrO2, Nb2O5, La2O3, Ta2O5, or HfO2 as a high refractive index dielectric material.

[0038] When viewed from a direction perpendicular to the side surface including side 15B of light-transmitting substrate 15, second optical film 19B reflects P-polarized light components, which are polarization components whose vibration direction is perpendicular to the side surface, and transmits S-polarized light components, which are polarization components whose vibration direction is parallel to side 15B. That is, the light transmitted through second optical film 19B has the same vibration direction as the light transmitted through wire grid 17 when viewed from above.

[0039] The second optical film 19B is made of a dielectric multilayer film whose thickness is adjusted so as to transmit the S-polarized component and reflect the P-polarized component of light incident on the second optical film 19B. In the light emitting element 100 of this embodiment, the second optical film 19B is made of 40 to 50 layers in total, each layer being made of SiO2 as a low-refractive index dielectric material and TiO2 as a high-refractive index dielectric material, alternately stacked.

[0040] In addition to the above-mentioned materials, the second optical film 19B may be made of Al2O3 as a low refractive index dielectric material, or ZrO2, Nb2O5, La2O3, Ta2O5, or HfO2 as a high refractive index dielectric material.

[0041] [Frame body part 21] Next, we will explain the configuration of the frame body 21. The frame body 21 is a frame-shaped body having a rectangular top surface and a through-hole 21O in the center that passes through the frame body 21 in the height direction. The frame body 21 is made of a material that can be processed into a desired shape, such as resin, metal such as aluminum (Al), or ceramics.

[0042] The light-emitting element section 11 and the phosphor layer 13 are disposed inside the through-hole 21O of the frame section 21. That is, the light-emitting element section 11 and the phosphor layer 13 are surrounded by the frame section 21 when viewed from above.

[0043] The upper surface 21S of the frame body portion 21 is located on the same plane as the lower surface of the light-transmitting substrate 15. In other words, the height of the upper surface 21S from the lower surface of the frame body portion 21 matches the height of the light-emitting element component 11 from the lower surface of the light-transmitting substrate 15.

[0044] A reflective film 27 is continuously formed on the upper surface 21S of the frame body portion 21. In the light-emitting element 100 of this embodiment, the reflective film 27 is a metallic reflective film made of a metal such as Al that can reflect light in the wavelength ranges of, for example, excitation light (blue light) and fluorescence (yellow light).

[0045] The reflective film 27 may be a dielectric multilayer film that is reflective to light incident on the reflective film 27 at an incident angle equal to or smaller than the critical angle when the light passes through the optical film 19. For example, the reflective film 27 may be formed by alternately layering SiO2 and TiO2 to a total of 48 layers, similar to the reflective film 26, to have a layer thickness that reflects light in the wavelength ranges of the excitation light and the fluorescence.

[0046] In addition, when the thickness of the light-transmitting substrate 15 is 700 μm, it is preferable that the distance L (see Figure 2) from the outer edge of the through hole 21O of the frame body portion 21 to the outer edge of the upper surface 21S be at least 400 μm, in order to reflect upward light that is incident on the upper surface 21S through the optical film 19 at an angle within the critical angle (e.g., 35° to 41.5°).

[0047] The frame body 21 is not limited to the above example as long as the upper surface 21S has light reflectivity. For example, the frame body 21 may be made of a metal that is reflective to excitation light and fluorescent light.

[0048] [Improvement of extraction efficiency of emitted light from light-emitting element 100] The improvement in the extraction efficiency of light emitted from the light emitting element 100 will be described below with reference to FIGS.

[0049] As described above, in the light emitting element 100, of the light incident on the wire grid 17, the P-polarized component, which is the polarization component perpendicular to the longitudinal direction of each of the metal bodies 17A constituting the wire grid 17, passes through the wire grid 17, and the S-polarized component, which is the polarization component parallel to the longitudinal direction, is reflected by the wire grid 17.

[0050] Furthermore, in the light-emitting element 100, as described above, the first optical film 19A transmits the P-polarized light component when viewed from a direction perpendicular to the side surface including the side 15A of the translucent substrate 15, and the second optical film 19B transmits the S-polarized light component when viewed from a direction perpendicular to the side surface including the side 15B of the translucent substrate 15.

[0051] With this configuration, for example, the P-polarized light component PP, which is reflected by the wire grid 17 and shown by the dashed line in FIG. 2, is transmitted through the first optical film 19A. On the other hand, for example, the S-polarized light component SP, which is reflected by the wire grid 17 and shown by the dashed line in FIG. 2, is reflected by the first optical film 19A.

[0052] Although not shown, the P-polarized light component PP reflected by the wire grid 17 is reflected by the second optical film 19B. On the other hand, the S-polarized light component SP reflected by the wire grid 17 is transmitted through the second optical film 19B.

[0053] The vibration directions of the P-polarized light component transmitted through wire grid 17, the P-polarized light component PP transmitted through first optical film 19A, and the S-polarized light component SP transmitted through second optical film 19B are all the same when viewed from above. That is, the P-polarized light component transmitted through wire grid 17, the P-polarized light component transmitted through first optical film 19A, and the S-polarized light component transmitted through second optical film 19B are all vibrating in a direction perpendicular to the extension direction of wire grid 17 (the direction along side 15B).

[0054] As a result, in the light-emitting element 100 of this embodiment, light can be emitted with the vibration directions of all the light emitted from the upper surface and side surfaces of the light-transmitting substrate 15 aligned. Furthermore, as described above, the reflective film 27 is formed on the upper surface 21S of the frame body portion 21, and therefore the P-polarized light component PP transmitted through the first optical film 19A is reflected by the upper surface 21S, for example, as indicated by the dashed dotted line in FIG. 2, and thereby travels upward in the drawing.

[0055] Therefore, according to the light-emitting element 100 of this embodiment, in addition to the light emitted through the wire grid 17, by utilizing light that has passed through the optical film 19 formed on the side surface of the light-transmitting substrate 15 and whose vibration direction is aligned with that of the light emitted through the wire grid 17, it is possible to increase the luminous flux of the light emitted from the light-emitting element 100. Therefore, according to the light-emitting element 100 of this embodiment, it is possible to improve the extraction efficiency of the emitted light compared to, for example, a case in which a light-reflecting film is formed on all of the side surfaces of the light-transmitting substrate 15.

[0056] In the light-emitting element 100 of this embodiment, the optical film 19 is formed on all four side surfaces of the translucent substrate 15, but this is not limited to this, and the optical film 19 may be formed on any one of the side surfaces of the translucent substrate 15.

[0057] When the optical film 19 is formed on one of the side surfaces of the light-transmitting substrate 15, for example, when the optical film 19 is formed on two of the side surfaces of the light-transmitting substrate 15, a light-reflecting film may be formed on the remaining two surfaces.

[0058] As a result, light is emitted from the two surfaces of the light-transmitting substrate 15 on which the optical film 19 is formed, and is reflected back inward from the other two surfaces. Therefore, this configuration in which the optical film 19 is partially formed is useful when, for example, it is desired to adjust the light distribution by strengthening the luminous flux of light emitted from the side surface on which the optical film 19 is formed, or when it is desired to strengthen the luminous flux of light emitted in a specific direction.

[0059] In the light-emitting element 100 of this embodiment, the optical film 19 may be formed entirely or partially on each side surface of the light-transmitting substrate 15. For example, the optical film 19 may be formed on a part of one side surface of the light-transmitting substrate 15, and a light-reflecting film may be formed on the remaining portion.

[0060] In the light-emitting device 100 of this embodiment, a cover film for protecting the surface of the wire grid 17 may be formed. This cover film is made of, for example, ZrO2 or SiO2, and is formed on the upper surface of the light-transmitting substrate 15 or the surface of the wire grid 17 by atomic layer deposition (ALD), sputtering, CVD, or the like.

[0061] [verification] 3 and 4, verification performed on a model simulating the light-emitting device 100 of this example and a model of a comparative example and the verification results will be described. In this verification, the luminous flux of each model in which the configurations of the reflective film and phosphor layer 13 formed on the side surface of the light-transmitting substrate 15 were changed was evaluated by simulation.

[0062] In this verification, lighting design analysis software Light Tools (manufactured by Synopsys) was used. Note that the refractive index shown below for this verification is the value when the light wavelength is 550 nm.

[0063] 3 is a cross-sectional view showing a simulation model M used in this verification. In this verification, model M is composed of a phosphor layer 33, a light-transmitting substrate 35 disposed on the phosphor layer 33, and an optical film 37 formed on the side surface of the light-transmitting substrate 35.

[0064] In Model M, the phosphor layer 33 has a square upper surface shape with a side length of 1000 μm and a thickness of 100 μm. In Model M, the phosphor layer 33 is made of a translucent resin with phosphor dispersed therein (hereinafter, this model will be referred to as "phosphor resin"), as in the present embodiment, and has a refractive index of 1.586. In addition, the side surfaces of the phosphor layer 33 are light-reflecting surfaces, and the reflectance for excitation light and fluorescent light is set to 100%.

[0065] In Model M, the light-transmitting substrate 35 has a square upper surface shape and a thickness of 700 μm. In Model M, the light-transmitting substrate 35 is made of glass as in this example, and has a refractive index of 1.51.

[0066] In model M, the upper surface 35U of the light-transmitting substrate 35 simulates the surface on which the wire grid 17 is formed, and the transmittance of the P-polarized component is set to 90%, the absorption rate of the P-polarized component is set to 10%, the reflectance of the S-polarized component is set to 90%, and the absorption rate of the S-polarized component is set to 10%.

[0067] In model M, the optical film 37 reproduces the optical film 19 of the light-emitting element 100 of this embodiment by defining the characteristics of the side surface of the light-transmitting substrate 15 and the characteristics of the air layer. In model M, an air layer with a thickness of 100 nm is provided on the side surface of the light-transmitting substrate 35, the characteristics of the side surface of the light-transmitting substrate 15 are a transmittance of 100% for the P-polarized component and a reflectance of 100% for the S-polarized component, and the surface characteristics of the air layer are a transmittance of 100% for light incident at an incident angle of 35° to 41.5° and a reflectance of 100% for light incident at other incident angles.

[0068] Here, we will explain three sample models that were compared with the configuration of the above example in this verification. The first sample model (sample model 1) is a model that uses a phosphor resin for the phosphor layer 33, just like model M, and uses the side surface as a light reflecting surface instead of the optical film 37 formed on the side surface of the light-transmitting substrate 35 of model M.

[0069] The second sample model (sample model 2) is a model that, like model M, uses an optical film 37 on the side of the translucent substrate 35, and uses a phosphor plate (refractive index 1.83) instead of phosphor resin to form the phosphor layer 33.

[0070] The third sample model (sample model 3) is a model in which the side surface of the translucent substrate 35 of model M is used as a light-reflecting surface instead of the optical film 37 formed on the side surface, and a phosphor plate is used instead of phosphor resin to form the phosphor layer 33.

[0071] In this verification, for each of the above-mentioned model M and sample models 1 to 3, the luminous flux of light emitted from the upper surface 35U of the translucent substrate 35 when 500 lm of light was scattered upwardly by Lambertian scattering from the lower surface 33L of the phosphor layer 33 of each model was evaluated by simulation.

[0072] Fig. 4 is a table showing the results of simulating the luminous flux of each of the above-mentioned model M and sample models 1 to 3. Comparing model M with sample model 1, Fig. 4 shows that the luminous flux of the example model is higher.

[0073] 4, comparing the example model with sample model 2, the luminous flux of the example model is higher. Also, comparing sample model 2 with sample model 3, the luminous flux of sample model 2 is higher.

[0074] From the above verification results, it can be seen that model M, in which optical film 37 is formed on the side surface of translucent substrate 35, can obtain a higher luminous flux than sample model 2, which uses a light-reflecting surface on the side surface, and sample model 3, which uses a phosphor plate as phosphor layer 33.

[0075] Therefore, from the above verification results, by forming the optical film 19 on the side surface of the light-transmitting substrate 15 in the light-emitting device 100 of this example, a higher luminous flux is expected compared to the case where a reflective film is formed on the side surface of the light-transmitting substrate 15. In particular, from the comparison results between Model M and Sample Model 2, a higher luminous flux is expected by using a phosphor resin for the phosphor layer 33.

[0076] [Method of manufacturing the light-emitting element 100] 1, 2, and 5 to 8, a method for manufacturing the light-emitting element 100 will be described below. In the following, an element consisting of the light-transmitting substrate 15, the wire grid 17, and the optical film 19 will be referred to as an optical element 50, and the method for manufacturing the optical element 50 will be mainly described. Each of FIGS. 5 to 8 is a perspective view showing an example of a manufacturing process for the optical element 50 of the light-emitting element 100.

[0077] 2, a frame body 21 is prepared in which a light emitting element section 11 and a phosphor layer 13 are formed in a through hole 21O (Step 1: frame body preparation step). In this step, for example, the phosphor layer 13 is formed on the light emitting element section 11, and a reflective film 26 is formed on the side surfaces of the light emitting element section 11 and the phosphor layer 13. Then, the frame body 21 made of resin is formed to surround the light emitting element section 11 and the phosphor layer 13.

[0078] Next, optical element 50 is prepared (Step 2: Optical element preparation step). First, a single light-transmitting substrate on which wire grid 17 has been formed in advance is diced into individual pieces of a desired size (for example, 1 mm square).

[0079] 5, a resist RE is formed on the upper surface of the light-transmitting substrate 15 to protect the wire grid 17. In addition, a resist RE is formed by spraying or dipping on the lower surface of the light-transmitting substrate 15 and on the side surfaces perpendicular to the extension direction of the wire grid 17. As a result, only the side surfaces of the light-transmitting substrate 15 parallel to the extension direction of the wire grid 17 are exposed.

[0080] Next, a first optical film 19A is formed on the side surface of the light-transmitting substrate 15 exposed from the resist RE by ALD or electron beam (EB) deposition, and the resist RE is removed. This makes it possible to manufacture the light-transmitting substrate 15 on which the first optical film 19A is formed, as shown in FIG.

[0081] 7, a resist RE is formed on the upper surface of the light-transmitting substrate 15 to protect the wire grid 17. In addition, the resist RE is formed by spraying or dipping on the lower surface of the light-transmitting substrate 15, the side surfaces parallel to the extension direction of the wire grid 17, and the first optical film 19A. As a result, only the side surfaces of the light-transmitting substrate 15 perpendicular to the extension direction of the wire grid 17 are exposed.

[0082] Next, the second optical film 19B is formed by ALD or EB deposition, and the resist RE is removed, thereby manufacturing the optical element 50 on which the first optical film 19A and the second optical film 19B are formed, as shown in FIG.

[0083] Finally, the optical element 50 prepared in step 2 is bonded to the upper surface of the phosphor layer 13 of the frame portion 21 prepared in step 1 using a light-transmitting bonding member or the like (step 3: optical element bonding step). This completes the manufacture of the light-emitting element 100 of this example.

[0084] Here, another method for manufacturing the optical element 50 will be described. Fig. 9 is a perspective view showing another example of the manufacturing process for the optical element 50 of the light-emitting element 100. In this manufacturing method, after forming a resist for protecting the wire grid 17 on the upper surface of each of the plurality of optical elements 50 manufactured in step 2 described above, each of the plurality of optical elements 50 is arranged so that a pair of side surfaces thereof are covered with a rectangular dummy bar DB made of Si, as shown in Fig. 9.

[0085] Next, a first optical film 19A is formed by ALD or EB vapor deposition on a pair of side surfaces of each optical element 50 that are not covered by the dummy bars DB. Thereafter, the dummy bars DB are arranged to cover the surfaces of each optical element 50 on which the first optical film 19A has been formed, and a second optical film 19B is formed by ALD or EB vapor deposition on the pair of side surfaces of each optical element 50 that are not covered by the dummy bars DB.

[0086] Thereafter, the dummy bar DB is removed, and the resist formed on the upper surface of the optical element 50 is removed, thereby manufacturing the optical element 50 on which the first optical film 19A and the second optical film 19B are formed.

[0087] The manufacturing method of the light-emitting element 100 is not limited to the above-described method. For example, the light-emitting element section 11 and the phosphor layer 13 may be formed, and the reflective film 26 may be formed on the side surfaces of the light-emitting element section 11 and the phosphor layer 13, and then the optical element 50 may be bonded to the upper surface of the phosphor layer 13. In other words, the frame section 21 may be provided later. [Explanation of symbols]

[0088] 100 light-emitting elements 11 Light emitting element section 13, 33 Phosphor layer 15, 35 Transparent substrate 17 Wire Grid 19, 37 Optical film 21 Frame body part 23 Semiconductor structural layer 24 Support substrate 26, 27 Reflective film 50 Optical Elements

Claims

1. a light-transmitting substrate having a rectangular flat plate-like upper surface and having light-transmitting properties; a polarizing element formed on an upper surface of the light-transmitting substrate, the polarizing element transmitting a polarized light component vibrating in one direction along one side of the upper surface of the light-transmitting substrate; an optical film formed on at least one of the side surfaces of the light-transmitting substrate, the optical film transmitting a polarized light component vibrating in the one direction and reflecting a polarized light component vibrating in another direction perpendicular to the one direction in a top view; An optical element comprising:

2. 2. The optical element according to claim 1, wherein the polarizing element is a wire grid consisting of a plurality of linear metal bodies arranged periodically in rows in the one direction on the upper surface of the light-transmitting substrate, each of the linear metal bodies extending along the other direction on the upper surface of the light-transmitting substrate.

3. 3. The optical element according to claim 1, wherein the optical film is made of a dielectric multilayer film.

4. 3. The optical element according to claim 1, wherein the optical film is formed over all of the side surfaces of the light-transmitting substrate.

5. the optical film is formed on one, two, or three of the side surfaces of the light-transmitting substrate; 3. The optical element according to claim 1, wherein a light-reflecting film having light reflectivity is formed on a side of the light-transmitting substrate on which the optical film is not formed.

6. a light emitting element portion including a semiconductor structure layer having a light emitting layer; a phosphor layer formed on the light emitting element portion and including a phosphor that is excited by light emitted from the light emitting layer to emit fluorescence; a light-reflecting film formed on a side surface of the light-emitting element portion and the phosphor layer and having light reflectivity; a light-transmitting substrate formed on the phosphor layer, the light-transmitting substrate having a rectangular flat plate-like upper surface; a polarizing element formed on an upper surface of the light-transmitting substrate, the polarizing element transmitting a polarized light component vibrating in one direction along one side of the upper surface of the light-transmitting substrate; an optical film formed on at least one of the side surfaces of the light-transmitting substrate, the optical film transmitting a polarized light component vibrating in the one direction and reflecting a polarized light component vibrating in another direction perpendicular to the one direction in a top view; A light-emitting element comprising:

7. 7. The light-emitting element according to claim 6, wherein the polarizing element is a wire grid consisting of a plurality of linear metal bodies arranged periodically in rows in the one direction on the upper surface of the light-transmitting substrate, each of the linear metal bodies extending along the other direction on the upper surface of the light-transmitting substrate.

8. 8. The light-emitting element according to claim 7, further comprising a frame-shaped frame portion having an upper surface extending along the lower surface of the light-transmitting substrate around the periphery of the lower surface, the upper surface having optical reflectivity.

9. 9. The light-emitting element according to claim 8, wherein a metal reflective film is formed over the upper surface of the frame portion.

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