Laser elements and VR modules using metasurfaces

Abstract

An embodiment provides a light-emitting device comprising: a substrate; a first electrode and a second electrode arranged separately on the substrate; a light-emitting portion arranged on the first electrode and the second electrode and electrically connected to the first electrode and the second electrode, the light-emitting portion including a first conductive type semiconductor layer, a light-emitting layer, and a second conductive type semiconductor layer; and a semiconductor substrate arranged on the light-emitting portion, the semiconductor substrate comprising a first surface including a first region on which a metasurface is formed, and a second surface opposite the first surface and in contact with the light-emitting portion, the metasurface protruding in a first direction from the second surface toward the first surface, and the second region of the first surface excluding the first region on which the metasurface is formed being flat.

Description

[Technical Field]

[0001] The present invention relates to a laser element and a virtual reality (VR) module, specifically to a laser element with an integrated metasurface and a VR module using the metasurface. [Background technology]

[0002] Vertical-cavity surface-emitting lasers (VCSELs), which are primarily used in conventional 3D modules, are used as infrared light sources to drive the modules. The key elements in constructing a VCSEL for implementing a typical 3D module are the wire-bonding process, the combination of the VCSEL with various optical elements, and the precision of alignment. However, the tolerances of these elements can cause a decrease in module performance and limit the miniaturization and integration of the module.

[0003] Metamaterials are new materials that are artificially modified from existing materials to take on properties not found in nature. Metasurfaces are two-dimensional planar structures created by using patterns smaller than the wavelength of light on two-dimensional thin films. As with metamaterials, they exhibit various optical properties that cannot be found in naturally occurring two-dimensional materials, and research is underway to apply them to various devices.

[0004] When applying metasurface to VCSEL to realize an optical system that realizes multiple functions with a single film, it is possible to improve performance by reducing the total thickness of existing modules.

[0005] We can propose an on-chip VCSEL with a flip-chip structure, where the GaAs substrate used for IR VCSELs is processed and integrated with a metasurface. When using a metasurface, it is possible to realize an optical module at the wafer level using a MEMS process, without the complicated alignment of existing VCSELs and optical elements.

[0006] In addition, in the construction of optical modules using conventional laser diodes, a combination of various optical systems such as collimating lenses, diffractive optics, and phase plates was an essential component to ensure the characteristics of the optical module. The combination of such various elements causes problems such as an increase in the module volume, and a decrease in efficiency due to individual product / manufacturing tolerances and a decrease in the transmittance of each element.

[0007] It is necessary to propose an optical system that realizes multiple functions in a single film by applying multiple metasurfaces to the optical system. This will enable the total thickness of existing elements to be reduced from several mm to less than 1 μm, improving performance. This can be applied to mobile cameras, vehicles, and ToF modules for IoT.

[0008] VR modules are optical systems that combine multiple optical modules using catadioptric optical systems and require a certain amount of space. Therefore, if the optical modules of a VR module are implemented with metasurfaces to reduce the size of the optical system, the performance and efficiency of the module can be improved. Summary of the Invention [Problem to be solved by the invention]

[0009] The embodiments provide vertical or flip-chip type laser devices.

[0010] Also provided is a laser device in which the substrate is treated with a metasurface.

[0011] It also provides a laser element at wafer level without complex alignment.

[0012] In addition, the module is made smaller and lighter, providing a laser element with increased efficiency.

[0013] An embodiment provides a VR module utilizing multiple metasurfaces.

[0014] It also provides a VR module with reduced size and thickness.

[0015] It also provides a VR module with improved transmittance.

[0016] In addition, the VR module can minimize alignment tolerances during assembly.

[0017] The problems to be solved by the examples are not limited to these, and may also include the objectives and effects that can be grasped from the means for solving the problems and embodiments described below. [Means for solving the problem]

[0018] A light emitting device according to an embodiment includes a substrate, a first electrode and a second electrode separated from each other and disposed on the substrate, a light emitting portion disposed on the first electrode and the second electrode and electrically connected to the first electrode and the second electrode, the light emitting portion including a first conductive type semiconductor layer, a light emitting layer, and a second conductive type semiconductor layer, and a semiconductor substrate disposed on the light emitting portion,

[0019] The semiconductor substrate includes a first surface including a first region on which a metasurface is formed, and a second surface facing the first surface and in contact with the light-emitting portion, the metasurface protruding from the second surface in a first direction toward the first surface, and the second region of the first surface excluding the first region on which the metasurface is formed may be flat.

[0020] The light-emitting portion of the light-emitting device according to the embodiment may include a first opening that adjusts the area of ​​the optical signal emitted in the first direction, and the area of ​​the first region in which the metasurface is formed may be larger than the area of ​​the first opening.

[0021] The metasurface of the light-emitting device according to the embodiment includes a plurality of unit structures,

[0022] The phase of the optical signal may be delayed by the plurality of unit structures.

[0023] The plurality of unit structures of the light emitting device according to the embodiment may include a plurality of circular cylinders or a plurality of rectangular cylinders protruding from the first surface toward the first direction.

[0024] The design of the unit structure of the light emitting device according to the embodiment may be isotropic, anisotropic, birefringent, polarization dependent or polarization independent.

[0025] The light emitting device according to the embodiment may be a vertical cavity surface emitting laser with a flip chip structure.

[0026] The semiconductor substrate of the light emitting device according to the embodiment may include at least one of GaAs (Gallium Arsenide) and GaN (Gallium Nitride).

[0027] The metasurface of the light-emitting device according to the embodiment can be formed by MEMS (Micro Electro Mechanical Systems).

[0028] The metasurface of the light emitting device according to the embodiment may perform at least one of focusing, divergence, and diffraction on the optical signal emitted from the light emitting portion.

[0029] The VR module according to the embodiment includes a display unit that irradiates an optical signal, an optical system including first to sixth optical units sequentially arranged on a path of the optical signal, and a substrate arranged between the fourth and fifth optical units, wherein the display unit and the first to sixth optical units are arranged at a predetermined interval from each other, the fourth optical unit focuses the optical signal, and the fifth optical unit delays the phase of the optical signal by half a wavelength, and at least one of the fourth or fifth optical unit may be a metasurface arranged on one surface of the substrate.

[0030] In the VR module of the embodiment, the first optical unit may be a linear polarizer that transmits the P wave of the optical signal, the second optical unit may be a wave plate that delays the phase of the optical signal by a quarter wavelength, the third optical unit may be a partial reflector that transmits 50% of the optical signal, the fifth optical unit may delay the phase of the optical signal by half a wavelength, and the sixth optical unit may be a linear polarizer that transmits the S wave of the optical signal.

[0031] The substrate of the VR module according to the embodiment may be a GaAs (Gallium Arsenide) substrate.

[0032] The fourth optical unit of the VR module of the embodiment may be a metasurface arranged on the surface from the substrate toward the third optical unit, and the fifth optical unit may be a metasurface arranged on the surface from the substrate toward the sixth optical unit.

[0033] The second optical unit of the VR module according to the embodiment may include a metasurface that delays the phase of the optical signal by a quarter wavelength.

[0034] The fifth optical unit of the VR module according to the embodiment can reflect the first circularly polarized light of the optical signal and can pass the second circularly polarized light, which is the first circularly polarized light delayed in phase by half a wavelength.

[0035] The optical signal of the VR module according to the embodiment can pass through the display unit, the first optical unit, the second optical unit, the third optical unit, the fourth optical unit and the substrate in sequence, then be reflected by the fifth optical unit and pass through the substrate and the fourth optical unit in sequence, and then be reflected by the third optical unit and pass through the fourth optical unit, the substrate, the fifth optical unit and the sixth optical unit in sequence.

[0036] The unit structure of the metasurface of the VR module according to the embodiment may be a cylindrical or rectangular prism.

[0037] The VR module of the embodiment includes a display unit that irradiates an optical signal, and an optical system including a first optical unit to a sixth optical unit that are sequentially arranged on the path of the optical signal, the display unit and the first optical unit to the sixth optical unit are arranged at a predetermined interval from each other, the fourth optical unit includes a first metasurface that focuses the optical signal, and a second metasurface that faces the first metasurface and delays the phase of the optical signal by a quarter wavelength, and the fourth optical unit can pass the optical signal irradiated from the display at least three times.

[0038] In the VR module of the embodiment, the first optical unit may be a linear polarizer that transmits the P wave of the optical signal, the second optical unit may be a wave plate that delays the phase of the optical signal by a quarter wavelength, the third optical unit may be a partial reflecting mirror that transmits 50% of the optical signal, the fifth optical unit may be a linear polarizer that reflects the P wave of the optical signal and transmits the S wave, and the sixth optical unit may be a linear polarizer that transmits the S wave of the optical signal.

[0039] The fourth optical unit of the VR module according to the embodiment may include GaAs (Gallium Arsenide).

[0040] The second optical unit of the VR module according to the embodiment may be a metasurface that delays the phase of the optical signal by a quarter wavelength.

[0041] The optical signal of the VR module according to the embodiment can pass through the display unit, the first optical unit, the second optical unit, the third optical unit and the fourth optical unit in sequence, then be reflected by the fifth optical unit and pass through the fourth optical unit, and then be reflected by the third optical unit and pass through the fourth optical unit, the fifth optical unit and the sixth optical unit in sequence.

[0042] The unit structure of the metasurface of the VR module of the embodiment is cylindrical or rectangular prism-shaped, the phase of the optical signal after passing through the metasurface varies depending on the diameter of the unit structure, the metasurface is made of a polymer, an insulator or a metal material, and the metasurface can be an isotropic, anisotropic, birefringent, polarization-dependent or polarization-independent structure.

[0043] The VR module according to the embodiment may include a frame for externally fixing the display unit and the optical system, and a band for fixing the VR module to a viewer. [Effects of the Invention]

[0044] According to an embodiment, a laser device can be provided in which the substrate is treated with a metasurface.

[0045] Also, the laser elements can be provided at wafer level without complex alignment.

[0046] Furthermore, it is possible to provide a laser element with increased efficiency by reducing the size and weight of the module.

[0047] According to the embodiment, a VR module using multiple metasurfaces can be implemented.

[0048] It is also possible to provide a VR module with reduced size and thickness.

[0049] It is also possible to provide a VR module with improved transmittance.

[0050] Furthermore, it is possible to provide a VR module that can minimize alignment tolerances during assembly.

[0051] The various beneficial advantages and effects of the present invention are not limited to the above, but will be more easily understood in the course of describing specific embodiments of the present invention. [Brief explanation of the drawings]

[0052] [Figure 1] FIG. 1 is a cross-sectional view of a conventional light-emitting element.

[0053] [Figure 2] FIG. 2 is a cross-sectional view of a light-emitting element according to an example.

[0054] [Figure 3] FIG. 1 is a phase diagram of a metasurface of a light-emitting element according to an example.

[0055] [Figure 4a] 1A to 1C are cross-sectional views of a light emitting device according to a manufacturing process of the light emitting device according to an embodiment of the present invention.

[0056] [Figure 4b] 1A to 1C are cross-sectional views of a light emitting device according to a manufacturing process of the light emitting device according to an embodiment of the present invention.

[0057] [Figure 4c] 1A to 1C are cross-sectional views of a light emitting device according to a manufacturing process of the light emitting device according to an embodiment of the present invention.

[0058] [Figure 4d] 1A to 1C are cross-sectional views of a light emitting device according to a manufacturing process of the light emitting device according to an embodiment of the present invention.

[0059] [Figure 4e] 1A to 1C are cross-sectional views of a light emitting device according to a manufacturing process of the light emitting device according to an embodiment of the present invention.

[0060] [Figure 4f] 1A to 1C are cross-sectional views of a light emitting device according to a manufacturing process of the light emitting device according to an embodiment of the present invention.

[0061] [Figure 4g] 1A to 1C are cross-sectional views of a light emitting device according to a manufacturing process of the light emitting device according to an embodiment of the present invention.

[0062] [Figure 4h] 1A to 1C are cross-sectional views of a light emitting device according to a manufacturing process of the light emitting device according to an embodiment of the present invention.

[0063] [Figure 4i] 1A to 1C are cross-sectional views of a light emitting device according to a manufacturing process of the light emitting device according to an embodiment of the present invention.

[0064] [Figure 4j] 1A to 1C are cross-sectional views of a light emitting device according to a manufacturing process of the light emitting device according to an embodiment of the present invention.

[0065] [Figure 4k] 1A to 1C are cross-sectional views of a light emitting device according to a manufacturing process of the light emitting device according to an embodiment of the present invention.

[0066] [Figure 4l] 1A to 1C are cross-sectional views of a light emitting device according to a manufacturing process of the light emitting device according to an embodiment of the present invention.

[0067] [Figure 5] FIG. 2 is a diagram illustrating the configuration of a light-emitting element according to an example.

[0068] [Figure 6] FIG. 1 is a conceptual diagram of a conventional optical module.

[0069] [Figure 7] FIG. 1 is a conceptual diagram of an optical module according to an embodiment.

[0070] [Figure 8] FIG. 1 is a phase diagram of an optical system according to an embodiment realized with a metasurface.

[0071] [Figure 9] 1 is an image showing a unit structure of a metasurface according to an embodiment.

[0072] [Figure 10] FIG. 2 is a configuration diagram of a VR module according to an embodiment.

[0073] [Figure 11] FIG. 2 is a conceptual diagram of a VR module according to an embodiment.

[0074] [Figure 12] FIG. 10 is a conceptual diagram of a VR module according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0075] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0076] However, the technical concept of the present invention is not limited to the described embodiments and may be embodied in various different forms, and one or more of the components of the embodiments may be selectively combined or substituted within the scope of the technical concept of the present invention.

[0077] Furthermore, unless otherwise clearly and specifically defined, terms (including technical and scientific terms) used in the embodiments of the present invention may be interpreted in a manner that would be commonly understood by a person of ordinary skill in the art to which the present invention pertains, and commonly used terms, such as dictionary-defined terms, may be interpreted in light of the contextual meaning of the relevant art.

[0078] Furthermore, the terms used in the embodiments of the present invention are intended to explain the embodiments and are not intended to limit the present invention.

[0079] In this specification, the singular can also include the plural unless otherwise specified in the context, and when it is stated as "A and (and) at least one (or more) of B and C," it can include one or more of all possible combinations of A, B, and C.

[0080] Additionally, terms such as first, second, A, B, (a), (b), etc. may be used to describe components of embodiments of the present invention.

[0081] Such terms are merely used to distinguish a component from other components, and are not intended to limit the nature, order, or sequence of the components.

[0082] Furthermore, when a component is described as being "coupled," "coupled," or "connected" to another component, it can include not only cases where the component is directly coupled, coupled, or connected to the other component, but also cases where the component is "coupled," "coupled," or "connected" by yet another component between the component and the other component.

[0083] Furthermore, when described as being formed or disposed "above or below" each component, "above" or "below" includes not only when two components are in direct contact with each other but also when one or more other components are formed or disposed between the two components. Furthermore, when described as "above or below," it can mean not only the upper direction but also the lower direction based on one component.

[0084] FIG. 1 is a cross-sectional view of a conventional light-emitting device.

[0085] Referring to FIG. 1, a conventional light emitting device 100 may include a substrate 110 , a first electrode 120 , a second electrode 130 , a light emitting portion 140 , a semiconductor substrate 150 and an optical element 160 .

[0086] The conventional light emitting device 100 may be a device that receives an electric power, converts it into an optical signal, and emits light. For example, the light emitting device 200 may be a vertical cavity surface emitting laser (VCSEL).

[0087] In the conventional light emitting device 100, the light emitting unit 140 receives power from the substrate 110 through the first electrode 120 and the second electrode 130 and can emit an optical signal. The optical signal can be emitted toward the semiconductor substrate 150, which can pass the optical signal. The semiconductor substrate 150 may have high transmittance for the optical signal. The optical signal that has passed through the semiconductor substrate 150 can pass through the optical element 160 and be emitted to the outside.

[0088] In the conventional light emitting device 100, the first electrode 120 and the second electrode 130 can be in direct contact with the substrate 110. Because the first electrode 120 and the second electrode 130 are all disposed on the lower surface of the light emitting portion 140 and are in direct contact with the substrate 110, the semiconductor substrate 150 and the optical element 160 can be disposed on the upper surface of the light emitting portion 140. The conventional light emitting device 100 has a feature in that the optical element 160 can be directly attached to the light emitting device 100. In the conventional light emitting device 100, multiple optical elements must be combined with the light emitting device and aligned on the light emitting device 100 to change the path of an optical signal.

[0089] FIG. 2 is a cross-sectional view of a light-emitting device according to an embodiment.

[0090] Referring to FIG. 2, the light emitting device 200 according to the embodiment may include a substrate 210, a first electrode 220, a second electrode 230, a light emitting portion 240, a semiconductor substrate 250, a metasurface 260, and a first opening 270.

[0091] The light emitting device 200 according to the embodiment includes a substrate 210, a first electrode 220 and a second electrode 230 separated from each other and disposed on the substrate 210, a light emitting portion 240 disposed on the first electrode 220 and the second electrode 230 and electrically connected to the first electrode 220 and the second electrode 230, the light emitting portion 240 including a first conductive type semiconductor layer, a light emitting layer, and a second conductive type semiconductor layer, and a semiconductor substrate 250 disposed on the light emitting portion 240. The semiconductor substrate 250 may include a first surface 251 including a first region 251a on which a metasurface is to be formed, and a second surface 252 facing the first surface 251 and in contact with the light emitting portion 240. The metasurface 260 protrudes from the second surface 252 in a first direction toward the first surface 251, and a second region 251b of the first surface 251 excluding the first region 251a on which the metasurface 260 is formed may be flat. Alternatively, the metasurface 260 may be formed to be recessed in a second direction from the first surface 251 toward the second surface 252 .

[0092] The light emitting device 200 may be a device that receives an electric current, converts it into an optical signal, and emits light. For example, the light emitting device 200 may be a vertical-cavity surface-emitting laser (VCSEL).

[0093] The light emitting device 200 can emit an optical signal when the light emitting unit 240 receives power from the substrate 210 through the first electrode 220 and the second electrode 230. The optical signal can be emitted toward the semiconductor substrate 250, which can pass the optical signal. The semiconductor substrate 250 may have high transmittance for the optical signal. The optical signal that has passed through the semiconductor substrate 250 can pass through the metasurface 260 and be emitted to the outside.

[0094] In the light emitting device 200, the first electrode 220 and the second electrode 230 may be in direct contact with the substrate 210. Since the first electrode 220 and the second electrode 230 are all disposed on the lower surface of the light emitting portion 240 and in direct contact with the substrate 210, the semiconductor substrate 250 and the metasurface 260 may be disposed on the upper surface of the light emitting portion 240.

[0095] The substrate 210 may receive electricity and transmit it to the light emitting unit 240 through the first electrode 220 and the second electrode 230. The substrate 210 may also support the light emitting unit 240. The first electrode 220 and the second electrode 230 may be disposed on and in contact with the upper surface of the substrate 210.

[0096] The first electrode 220 and the second electrode 230 may be separately disposed on the substrate 210. The first electrode 220 and the second electrode 230 may transmit electricity between the substrate 210 and the light emitting portion 240. The first electrode 220 and the second electrode 230 may be disposed on and in contact with an upper surface of the substrate 210. The first electrode 220 and the second electrode 230 may be disposed on and in contact with a lower surface of the light emitting portion 240. For example, the first electrode 220 and the second electrode 230 may be a p-type metal and an n-type metal, respectively.

[0097] The light emitting unit 240 may generate an optical signal when supplied with electricity. The light emitting unit 240 may include a first conductive type semiconductor layer, a light emitting layer, and a second conductive type semiconductor layer. The light emitting unit 240 may emit an optical signal toward an upper surface of the light emitting unit 240 due to a difference in reflectivity of the optical signal between the first conductive type semiconductor layer and the second conductive type semiconductor layer. The light emitting unit 240 may emit an optical signal in a first direction. The first direction may be a direction from the light emitting unit 240 toward the semiconductor substrate 250. The first electrode 220 and the second electrode 230 may be disposed on and in contact with a lower surface of the light emitting unit 240. The semiconductor substrate 250 may be disposed on and in contact with an upper surface of the light emitting unit 240. The light emitting unit 240 may include a first opening 270.

[0098] The first opening 270 may adjust the area of ​​the optical signal emitted from the light emitting portion 240. The first opening 270 may be disposed on a path along which the optical signal is emitted in a first direction from the light emitting portion 240 toward the semiconductor substrate 250. The first opening 270 may allow the optical signal to pass through the semiconductor substrate 250 within the light emitting portion 240 depending on the area of ​​the first opening 270. The first opening 270 may function as an aperture of the light emitting device 200. For example, if the area of ​​the first opening 270 is c, the optical signal emitted from the light emitting portion 240 may pass through the semiconductor substrate 250 by an amount corresponding to the area of ​​c.

[0099] The semiconductor substrate 250 may pass an optical signal emitted from the light emitting unit 240. The semiconductor substrate 250 may be disposed on and in contact with an upper surface of the light emitting unit 240. The semiconductor substrate 250 may include a first surface 251 and a second surface 252.

[0100] The first surface 251 may be a surface of the semiconductor substrate 250 disposed in a direction opposite to the direction toward the light emitting unit 240. The first surface 251 may be a surface of the substrate 250 disposed in a direction in which an optical signal is emitted. A metasurface 260 may be disposed on the first surface 251. The metasurface 260 may be disposed on the first surface 251 in a form that protrudes in the first direction in which an optical signal is emitted. The first surface 251 may include a first region 251a and a second region 251b.

[0101] The first region 251a may be disposed at the center of the first surface 251. The metasurface 260 may be disposed in the first region 251a. The metasurface 260 may be disposed in the first region 251a in a form that protrudes in a first direction in which an optical signal is emitted. The optical signal that passes through the semiconductor substrate 250 may be emitted to the outside up to an area corresponding to the area of ​​the first region 251a. For example, if the area of ​​the first region 251a is a, the optical signal corresponding to the area a may pass through the metasurface 260 of the first region 251a and be emitted to the outside.

[0102] The area a of the first region 251a may be larger than the area c of the first opening 270. Since the first region 251a is a region from which the optical signal that has passed through the opening 270 is emitted, the area a of the first region 251a may include the entire area of ​​the optical signal that has passed through the opening 270.

[0103] The second region 251b may be disposed on the edge of the first surface 251. The second region 251b may be disposed in a form surrounding the first region 251a. The second region 251b may be flat and not have the metasurface 260 disposed therein. The area of ​​the second region 251b may be b. The area b of the second region 251b may be smaller than the area of ​​the first region 251a. However, the area b of the second region 251b may be larger than the area of ​​the first region 251a.

[0104] The second surface 252 may be a surface of the semiconductor substrate 250 that is disposed in a direction toward the light emitting unit 240. The second surface 252 may be disposed in a direction opposite to the first surface 251 of the semiconductor substrate 250. The second surface 252 may be a surface that contacts the light emitting unit 240. The second surface 252 may be a surface that allows an optical signal emitted from the light emitting unit 240 to pass through the semiconductor substrate 250.

[0105] The semiconductor substrate 250 transmits optical signals and may have high transmittance for optical signals. The semiconductor substrate 250 according to the embodiment may include at least one of GaAs (Gallium Arsenide) and GaN (Gallium Nitride).

[0106] The metasurface 260 can delay the phase of an optical signal to change the path of the optical signal. The metasurface 260 can be disposed on the first surface 251 of the semiconductor substrate 250. The metasurface 260 can be disposed on a portion of or the entire first surface 251 of the semiconductor substrate 250. The metasurface 260 can be disposed on a path along which an optical signal is emitted and passes through the semiconductor substrate 250. The metasurface 260 can be disposed to include the entire surface area along which the optical signal passes through the semiconductor substrate 250. The metasurface 260 can be disposed on the first region 251a of the first surface 251. The metasurface 260 can be disposed over an area corresponding to the first region 251a of the first surface 251. For example, if the area of ​​the first region 251a is a, the metasurface 260 can be disposed over an area a. The area a of the first region 251a on which the metasurface 260 is disposed can be greater than the area c of the first opening 270. Since the first region 251a where the metasurface 260 is arranged is the region where the optical signal that has passed through the opening 270 is emitted, the area a of the first region 251a can include the entire area of ​​the optical signal that has passed through the opening 270.

[0107] The metasurface 260 can realize an optical element in an ultra-thin film form by arranging multiple nano-unit structures. When an optical signal passes through the metasurface, the phase of the optical signal can be delayed to change the path of the optical signal. By using the metasurface, the total thickness of multiple optical elements can be reduced from several mm to less than 1 μm, improving the performance of the optical module.

[0108] The metasurface 260 according to the embodiment may protrude in a first direction from the second surface 252 toward the first surface 251. The metasurface 260 may protrude in the first direction onto the first surface 251 of the semiconductor substrate 250 to replace an optical element. The metasurface 260 may be formed by etching the surface of the semiconductor substrate 250.

[0109] The light emitting portion 240 according to the embodiment may include a first opening 270 that adjusts the area of ​​the optical signal emitted in the first direction, and the area a of the metasurface 260 may be larger than the area c of the first opening 270.

[0110] The first opening 270 may adjust the area of ​​the optical signal emitted from the light emitting portion 240. The first opening 270 may be disposed on a path along which the optical signal is emitted in a first direction from the light emitting portion 240 toward the semiconductor substrate 250. The first opening 270 allows the optical signal to pass through the light emitting portion 240 to the semiconductor substrate 250 according to the area of ​​the first opening 270. The first opening 270 may function as an aperture of the light emitting device 200. For example, if the area of ​​the first opening 270 is c, the optical signal emitted from the light emitting portion 240 may pass through the semiconductor substrate 250 by an amount corresponding to the area of ​​c. The area a of the first region 251a may be larger than the area c of the first opening 270. Since the first region 251a is a region through which the optical signal passing through the opening 270 is emitted, the area a of the first region 251a may include the entire area of ​​the optical signal passing through the opening 270.

[0111] The metasurface 260 according to the embodiment may be formed toward a first direction in which an optical signal is emitted. The metasurface 260 may protrude in the first direction from the first surface 251 of the semiconductor substrate 250 to replace an optical element. The metasurface 260 may be formed by etching the surface of the semiconductor substrate 250 without any additional process in the manufacturing process of the light emitting device 200, by forming the metasurface 260 to protrude in the first direction from the first surface 251 exposed to the outside of the semiconductor substrate 250.

[0112] The metasurface 260 according to the embodiment includes a plurality of unit structures, and the phase of an optical signal can be delayed by the plurality of unit structures. The metasurface 260 can be composed of a number of nano unit structures, and the unit structures can have different diameters, heights, shapes, materials, etc. depending on the function of the optical element to be realized. The unit structures of the metasurface 260 can have different diameters, so that the phase change of the optical signal after passing through the unit structures can be different.

[0113] The plurality of unit structures according to the embodiment may include a plurality of circular cylinders or a plurality of rectangular cylinders protruding from the first surface 251 in the first direction.

[0114] The design of the unit structures according to the embodiments can be isotropic, anisotropic, birefringent, polarization dependent or polarization independent.

[0115] The light emitting device 200 according to the embodiment may be a vertical cavity surface emitting laser with a flip chip structure.

[0116] In the case of a flip-chip structure, the electrodes are disposed between the light emitting unit 240 and the substrate 210 of the light emitting device 200 and disposed on one side of the light emitting device 200, so that the optical element can be disposed on the other side of the light emitting device 200. Therefore, the metasurface 260 of the light emitting device 200 according to the embodiment can be disposed on the semiconductor substrate 250, which is the opposite side of the light emitting device 200 in the flip-chip structure from the side on which the electrodes are disposed.

[0117] The semiconductor substrate 250 according to the embodiment may include at least one of GaAs (Gallium Arsenide) and GaN (Gallium Nitride).

[0118] The semiconductor substrate 250 may have high optical transmittance because it passes an optical signal emitted from the light emitting portion 240. The semiconductor substrate 250 may include at least one of GaAs (Gallium Arsenide) and GaN (Gallium Nitride), which have high optical transmittance. The metasurface 260 may be made of a heterostructure material.

[0119] The metasurface 260 according to the embodiment can be formed by MEMS (Micro Electro Mechanical Systems).

[0120] The metasurface 260 according to the embodiment can perform at least one of focusing, divergence, and diffraction on the optical signal emitted from the light emitting portion.

[0121] The metasurface 260 according to the embodiment can focus the optical signal emitted from the light emitting unit. The metasurface 260 can function as a focusing lens that focuses the optical signal emitted from the light emitting unit 240. The metasurface 260 according to the embodiment can diverge the optical signal emitted from the light emitting unit 240. The metasurface 260 can function as a lens that diverges the optical signal emitted from the light emitting unit 240. The metasurface 260 according to the embodiment can diffract the optical signal emitted from the light emitting unit 240. The metasurface 260 can function as a diffractive optical element (DOE) that diffracts the optical signal emitted from the light emitting unit 240.

[0122] FIG. 3 is a phase diagram of the metasurface of the light-emitting device according to the example.

[0123] A phase diagram can be derived to realize a light-emitting device according to an embodiment using a metasurface. The phase diagram is derived based on the performance and effect of the optical element and shows the phase of an optical signal depending on the position where the optical signal passes through the optical element.

[0124] Referring to FIG. 3, the phase diagram of the collimator, which is an optical element, can be shown as in FIG.

[0125] 4a to 4l are cross-sectional views of the light emitting device according to the manufacturing process of the light emitting device according to the embodiment.

[0126] 4a to 4l, the light emitting device according to the embodiment may be formed by MEMS (Micro Electro Mechanical Systems). Referring to FIG. 4a to 4l, the light emitting device according to the embodiment may be formed by MEMS according to the sequence of FIG. 4a to 4l.

[0127] FIG. 4a shows the epitaxial growth of the light-emitting device.

[0128] 4a, epitaxial growth for forming a light emitting device can be performed using metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). While GaAs is used in this example, this can be applied to various heterojunction structures such as GaN and InGaAlP. A light emitting portion 240 can be formed on a semiconductor substrate 250.

[0129] FIG. 4b shows the SiO2 deposition mask of the light-emitting device.

[0130] 4b, a dielectric material such as SiO2 or a metal may be used as a means for selectively performing epitaxial etching when performing mesa etching of FIG. 4c. An SiO2 mask 241 may be formed on the semiconductor substrate 250 and the light emitting portion 240.

[0131] FIG. 4c shows the mesa etching and SiO2 removal of the light emitting device.

[0132] 4c, mesa etching is performed using reactive ion etching (RIE) or ion coupled plasma (ICP)-RIE. Then, the SiO2 mask used for deposition masking is removed using wet etching or ashing. A portion of the light emitting portion 240 may be mesa-etched, and the SiO2 mask 241 may be removed.

[0133] FIG. 4d shows the aperture oxidation of the light-emitting element.

[0134] Referring to FIG. 4 d , a first opening 270 may be formed in a portion of the interior of the light emitting part 240 .

[0135] FIG. 4e shows the SiO2 passivation of the light-emitting device.

[0136] Referring to FIG. 4e, a SiO 2 passivation 241 may be formed on the surface of the mesa-etched light emitting portion 240.

[0137] FIG. 4f shows the BCB spin coating and etching of the light-emitting device.

[0138] Referring to FIG. 4f, a BCB spin 242 may be coated and etched onto a portion of the SiO 2 passivation 241 .

[0139] FIG. 4g shows SiO2 passivation for layer opening of the light emitting device.

[0140] 4g, a second opening 243 may be formed in a portion of the SiO2 passivation 241. The second opening 243 may be a portion for contacting the light emitting portion 240 with an electrode.

[0141] 4d-4g, which show the process for forming the aperture of an epitaxial semiconductor laser, the laser aperture can be formed depending on the size of the SiO2 layer removed when performing the process of Figures 4f-g, which can be a factor that determines the quality of the output laser beam (beam parameter product, BPP).

[0142] FIG. 4h shows the n-GaAs layer thinning of the light emitting device.

[0143] Referring to FIG. 4h, the thinning of the n-GaAs may be for the purpose of avoiding loss of optical efficiency due to absorption, total internal reflection, etc. of the semiconductor substrate 250 when implementing a flip-chip structure of the semiconductor laser.

[0144] FIG. 4i shows the P-electrode & bump fabrication of the light-emitting device.

[0145] Referring to FIG. 4i, a plurality of bumps 244 may be formed in contact with the light emitting portion 240 through the BCB spin 242 or the second opening 243, and the first electrode 220 and the substrate 210 may be formed in contact with the plurality of bumps 244.

[0146] FIG. 4j shows the n-electrode fabrication of the light-emitting device.

[0147] Referring to FIG. 4j, a second electrode 230 may be formed in contact with the substrate 210.

[0148] FIG. 4k shows the n-electrode & Via filling fabrication of the light-emitting device.

[0149] Referring to FIG. 4k, a via fill 245 may be formed in contact with the second electrode 230 and the substrate 210, allowing the second electrode 230 to contact the light emitting portion.

[0150] 4i to 4k, this may correspond to a process of forming an electrode that supplies an electrical pumping source for emitting light from a light emitting device having an implemented filp-chip structure.

[0151] FIG. 4l shows the integration of metasurface into a light-emitting device.

[0152] Referring to FIG. 4l, this may be a process of forming a metasurface 260 on a surface used in a semiconductor substrate 250 of a flip-chip type light emitting device structure.

[0153] Here, the semiconductor substrate 250 used to form the metasurface 260 can be selected in consideration of the refractive index (n) and extinction coefficient (k). These values ​​can be measured using spectroscopic ellipsometry.

[0154] 4l, GaAs used in the semiconductor substrate 250 of the embodiment has a high refractive index of n=3.506 and k=0.009 at an operating wavelength of 940 nm and a low absorption coefficient. These characteristics may indicate that GaAs is a suitable material for all dielectric metasurfaces in the IR region.

[0155] The process for forming the GaAs-based metasurface 260 of the above-described embodiment is as follows. First, PMMA, which is used as a photosensitive agent, is spin-coated onto the GaAs substrate. Then, using e-beam lithography, a mask having the shape of the designed metasurface 260 is patterned and developed. Next, using reactive ion etching (RIE) or ion coupled plasma (ICP)-RIE, the GaAs substrate on which the photosensitive agent has been selectively coated is selectively etched. Finally, the PMMA layer is removed to realize the metasurface 260 of the embodiment.

[0156] The metasurface according to the embodiment can be formed on a semiconductor substrate at the end of the MEMS process of the light emitting device.

[0157] FIG. 5 is a diagram showing the configuration of a light emitting device according to an example.

[0158] Referring to FIG. 5, the light emitting device 200 according to the embodiment may include a substrate 210 , a first electrode 220 , a second electrode 230 , a light emitting portion 240 , a semiconductor substrate 250 and a metasurface 260 .

[0159] FIG. 6 is a conceptual diagram of a conventional optical module.

[0160] 6, a conventional optical module 1100 may include a light emitting unit 1110, a first optical unit 1120, and a second optical unit 1130. The conventional optical module 1100 in FIG. 6 is provided for comparison with the optical module 1200 according to an embodiment of the present invention, and the embodiment of the present invention is not limited thereto.

[0161] The light emitting unit 1110 can emit an optical signal.

[0162] The first optical unit 1120 and the second optical unit 1130 may be optical elements that change the phase of an optical signal, such as a collimating lens, a diffractive optical element, a phase plate, or a focusing lens.

[0163] In the conventional optical module 1100, an optical signal irradiated from the light emitting unit 1110 passes through multiple optical units, thereby changing the optical signal into a desired path or arrangement. For example, the first optical unit 1120 may be a collimator, and the second optical unit 1130 may be a diffractive optical element (DOE). The optical signal emitted from the light emitting unit 1110 of the conventional optical module 1100 may pass through the first optical unit 1120 and then the second optical unit 1130 before being emitted.

[0164] The light emitting unit 1110, the first optical unit 1120, and the second optical unit 1130 may be spaced apart by a predetermined distance. For example, the light emitting unit 1110 and the first optical unit 1120 may be spaced apart by a first distance, and the first optical unit 1120 and the second optical unit 1130 may be spaced apart by a second distance. To adjust the optical signal emitted from the second optical unit 1130, the positions of the light emitting unit 1110, the first optical unit 1120, and the second optical unit 1130 may be adjusted, and accordingly, a space is required to accommodate the light emitting unit 1110, the first optical unit 1120, and the second optical unit 1130.

[0165] That is, the conventional optical module 1100 requires a certain level of thickness or volume since a plurality of optical parts are combined and arranged.

[0166] FIG. 7 is a conceptual diagram of an optical module according to an embodiment.

[0167] Referring to FIG. 7, an optical module 1200 according to the embodiment may include a light emitting unit 1210 and an optical unit 1220 .

[0168] The light emitting unit 1210 can emit a light signal.

[0169] The optical unit 1220 may include a metasurface that functions as an optical element that changes the phase of an optical signal, such as a collimating lens, a diffractive optical element, a phase plate, or a focusing lens. That is, the optical unit 1220 may perform multiple functions simultaneously. For example, the optical signal passing through the optical unit 1220 may perform the functions of at least two of a collimating lens, a diffractive optical element, a phase plate, and a focusing lens. This may be performed by a first surface 1220a and a second surface 1220b, which correspond to different surfaces of the optical unit 1220. Here, the first surface 1220a and the second surface 1220b may correspond to different metasurfaces.

[0170] The first surface 1220a of the optical unit 1220 may protrude toward the light emitting unit 1210, and the second surface 1220b may protrude in a direction opposite to the direction toward the light emitting unit 1210. That is, the metasurface of the first surface 1220a and the metasurface of the second surface 1220b may protrude in different directions.

[0171] The phase of the optical signal passing through first surface 1220a may be changed by the metasurface, and may have a different phase from the optical signal output from light emitting unit 1210. In addition, the phase of the optical signal passing through second surface 1220b may be changed by the metasurface, and may have a different phase from the optical signal passing through first surface 1220a. Here, the optical signal having a different phase may be a characteristic of an optical signal corresponding to one of the functions of the plurality of optical elements.

[0172] The protrusions on the first surface 1220a and the second surface 1220b may protrude in the same direction. However, the protrusions on the first surface 1220a and the second surface 1220b may protrude in different directions, rather than in the same or opposite directions. Furthermore, the protrusions on the first surface 1220a and the second surface 1220b may have different diameters, positions, heights, etc.

[0173] The optical portion 1220 according to the embodiment may include a metasurface disposed on both surfaces of a single substrate.

[0174] In the optical module 1200 according to the embodiment, an optical signal irradiated from the light emitting unit 1210 passes through a plurality of metasurfaces, thereby changing the optical signal into a desired path or arrangement. For example, the first surface 1220a may correspond to a collimator, and the second surface 1220b may correspond to a diffractive optical element (DOE). The optical signal emitted from the light emitting unit 1210 of the conventional optical module 1200 may pass through the first surface 1220a and then pass through the second surface 1220b before being emitted.

[0175] Metasurfaces can realize optical elements in the form of ultra-thin films by arranging multiple nano-unit structures. When an optical signal passes through a metasurface, the phase of the optical signal is delayed, changing the path of the optical signal. By using metasurfaces, the total thickness of multiple optical elements can be reduced from several mm to less than 1 μm, improving the performance of optical modules.

[0176] The optical unit 1220 according to this embodiment may be formed by implementing a metasurface on both surfaces of a single substrate. When two metasurfaces are arranged on a single substrate, the functions of two optical elements can be implemented on one substrate, thereby further reducing the total thickness of the optical element. Accordingly, the volume of the optical module 1200 including the optical unit 1220 may be further reduced.

[0177] Furthermore, the optical module 1200 may include an optical unit 1220 having multiple functions, thereby providing an optical module 1200 with reduced weight.

[0178] FIG. 8 is a phase diagram in which the optical section according to the embodiment is realized by a metasurface.

[0179] To realize the optical unit according to the embodiment with a metasurface, a phase diagram of the optical unit can be derived. The phase diagram is derived based on the performance and effect of the optical element and shows the phase of the optical signal depending on the position where the optical signal passes through the optical element.

[0180] Referring to FIG. 8, the phase diagram of a collimator, which is an optical element, can be shown as in FIG.

[0181] FIG. 9 is an image showing the unit structure of a metasurface according to an embodiment.

[0182] The metasurface may be composed of a number of nano-unit structures, and the unit structures may have different diameters, heights, shapes, materials, etc. depending on the function of the optical element to be realized.

[0183] Referring to FIG. 9, the unit structures of the metasurface according to the embodiment can have different diameters, which can cause the phase change of the optical signal after the optical signal passes through the unit structure to differ.

[0184] FIG. 10 is a configuration diagram of a VR module according to an embodiment.

[0185] Referring to FIG. 10, the VR module 1300 of the embodiment may include a display unit 1310, a first optical unit 1320, a second optical unit 1330, a third optical unit 1340, a fourth optical unit 1350, a substrate 1360, a fifth optical unit 1370 and a sixth optical unit 1380.

[0186] The VR module 1300 may be an optical module optimized for playing and viewing images and the like in a virtual world that is not a real space. The VR module 1300 may include a display unit 1310 that transmits images and the like, an optical system including multiple optical units, a frame 1 that externally fixes the display unit 1310 and the optical system, and a band 2 that can fix the VR module 1300 to a viewer. Optical signals such as images transmitted from the display unit 1310 may pass through the optical system including multiple optical elements and enter the viewer's eyes. The frame 1 includes an opening, and the optical signals that pass through the optical system may enter the viewer's eyes through the opening, and the frame 1 can be fixed to the viewer's eyes through the band 2. The band 2 may be worn around the viewer's head to fix the frame 1 in front of the viewer's eyes.

[0187] The display unit 1310 can emit a light signal.

[0188] The display unit 1310 may be a display panel that emits optical signals and can output image information of the VR module. The type, size, and resolution of the display unit 1310 are not limited. For example, the display unit 1310 may include an LCD, an OLED, an OLEDoS, or a MicroLED. For example, the size of the display unit 1310 may be 6.225 cm x 5.75 cm, and the resolution may be 1170 pixels x 1080 pixels.

[0189] The first to sixth optical units 1320, 1330, 1340, 1350, 1370, and 1380 may be optical elements that change the phase of an optical signal output from the display unit 1310. The first to sixth optical units 1320, 1330, 1340, 1350, 1370, and 1380 may be referred to as an optical system. By including multiple optical units corresponding to the first to sixth optical units 1320, 1330, 1340, 1350, 1370, and 1380 in the optical system, the focal length between the image of the VR module and the user can be reduced. In other words, by using the first to sixth optical units 1320, 1330, 1340, 1350, 1370, and 1380, the VR module 1300 may be made lighter and smaller.

[0190] The substrate 1360 may be a substrate that allows optical signals to pass through, and may have high optical transmittance because the substrate 1360 must be able to pass optical signals.

[0191] The optical elements included in the VR module 1300 will be described below with reference to FIGS.

[0192] FIG. 11 is a conceptual diagram of a VR module according to an embodiment.

[0193] Referring to FIG. 11, the VR module 1300 according to the embodiment includes a display unit 1310 that emits an optical signal, an optical system including first to sixth optical units 1320, 1330, 1340, 1350, 1370, and 1380 that are sequentially arranged on the path of the optical signal, and a substrate 1360 that is arranged between the fourth optical unit 1350 and the fifth optical unit 1370. The display unit 1310 and the first to sixth optical units 1320, 1330, 1340, 1350, 1370, and 1380 are spaced apart from each other by a predetermined distance. The fourth optical unit 1350 focuses the optical signal, and the fifth optical unit 1370 delays the phase of the optical signal. At least one of the fourth optical unit 1350 or the fifth optical unit 1370 may be a metasurface arranged on one surface of the substrate 1360.

[0194] The display unit 1310 may emit an optical signal. The display unit 1310 may emit the optical signal to the first optical unit 1320. The display unit 1310 may be arranged along a first direction. The display unit 1310 may be a display panel that emits an optical signal and may output image information of the VR module. The display unit 1310 may include an LCD, an OLED, an OLEDoS, or a MicroLED.

[0195] The first to sixth optical units 1320, 1330, 1340, 1350, 1370, and 1380 may be optical elements that change the phase of an optical signal, such as a collimating lens, a diffractive optical element, a phase plate, a focusing lens, etc. The first to sixth optical units 1320, 1330, 1340, 1350, 1370, and 1380 may be arranged at predetermined intervals along a second direction perpendicular to the first direction on a path of an optical signal irradiated from the display unit 1310, and the first to sixth optical units 1320, 1330, 1340, 1350, 1370, and 1380 may be arranged in the same first direction as the display unit 1310. The first to sixth optical units 1320, 1330, 1340, 1350, 1370, and 1380 may be spaced apart at regular intervals or at different intervals. The spaces between the first to sixth optical units 1320, 1330, 1340, 1350, 1370, and 1380 are empty spaces, and air may act as an intermediate medium for optical signals. The first to sixth optical units 1320, 1330, 1340, 1350, 1370, and 1380 may be referred to as an optical system. Each of the first to sixth optical units 1320, 1330, 1340, 1350, 1370, and 1380 may be an optical element in the form of a thin film or a flat plate. In addition, the first to sixth optical units 1320, 1330, 1340, 1350, 1370, and 1380 are optical elements that have a certain thickness and are spaced apart, so they require a certain amount of space to accommodate them. By including multiple optical units corresponding to the first to sixth optical units 1320, 1330, 1340, 1350, 1370, 1380, and 1380 in the optical system, it is possible to reduce the focal length between the image of the VR module and the user.

[0196] The first optical unit 1320 can pass an optical signal emitted from the display unit 1310. The first optical unit 1320 can be spaced a predetermined distance from the display unit 1310, and the first optical unit 1320 can be arranged in a direction parallel to the display unit 1310. The first optical unit 1320 can be arranged between the display unit 1310 and the second optical unit 1330.

[0197] According to an embodiment, the first optical unit 1320 may be a linear polarizer that transmits P-wave of the optical signal. The first optical unit 1320 may transmit only P-wave polarized light of the optical signal irradiated from the display unit 1310 and reflect S-wave polarized light.

[0198] The second optical unit 1330 can pass the optical signal that has passed through the first optical unit 1320. The second optical unit 1330 can be disposed at a predetermined distance from the first optical unit 1320, and the second optical unit 1330 can be disposed in a direction parallel to the first optical unit 1320. The second optical unit 1330 can be disposed between the first optical unit 1320 and the third optical unit 1340.

[0199] According to an embodiment, the second optical unit 1330 may be a wave plate that delays the phase of the optical signal by a quarter wavelength. The second optical unit 1330 may delay the phase of the optical signal that has passed through the first optical unit 1320 by a quarter wavelength compared to the phase of the optical signal before passing through the first optical unit 1320.

[0200] The second optical portion 1330 according to the embodiment is also a metasurface that delays the phase of the optical signal by a quarter wavelength.

[0201] The third optical unit 1340 can pass the optical signal that has passed through the second optical unit 1330. The third optical unit 1340 can be disposed at a predetermined distance from the second optical unit 1330, and the third optical unit 1340 can be disposed in a direction parallel to the second optical unit 1330. The third optical unit 1340 can be disposed between the second optical unit 1330 and the fourth optical unit 1350.

[0202] In this embodiment, the third optical unit 1340 may be a partially reflecting mirror that transmits 50% of the optical signal. The third optical unit 1340 may transmit 50% of the optical signal that has passed through the second optical unit 1330 and reflect the other 50%.

[0203] The fourth optical unit 1350 can pass the optical signal that has passed through the third optical unit 1340. The fourth optical unit 1350 can be disposed at a predetermined distance from the third optical unit 1340, and the fourth optical unit 1350 can be disposed in a direction parallel to the third optical unit 1340. The fourth optical unit 1350 can be disposed between the third optical unit 1340 and the substrate 1360.

[0204] The fourth optical unit 1350 according to the embodiment may focus an optical signal. The fourth optical unit 1350 may focus an optical signal that has passed through the third optical unit 1340. For example, the fourth optical unit 1350 may be a lens that focuses an optical signal onto a focal point at a certain distance.

[0205] According to the embodiment, the fourth optical unit 1350 may be a metasurface disposed on one surface of the substrate 1360. The fourth optical unit 1350 may be formed by etching the surface of the substrate 1360. The metasurface of the fourth optical unit 1350 may be an optical element having a focusing function in an ultrathin film form by arranging a plurality of nano-unit structures. When an optical signal passes through the metasurface, the phase of the optical signal may be delayed to change the path of the optical signal. When the metasurface is used, the total thickness of the plurality of optical elements may be reduced from several mm to 1 μm or less, thereby improving the performance of the optical module.

[0206] The fourth optical unit 1350 may be disposed on a first surface 1360a of the substrate 1360. The first surface 1360a may be disposed in a direction toward the third optical unit 1340 of the substrate 1360. The fourth optical unit 1350 may be a metasurface formed by etching the first surface 1360a of the substrate 1360. The fourth optical unit 1350 may be an optical element formed by coating the first surface 1360a of the substrate 1360.

[0207] The substrate 1360 can transmit the optical signal that has passed through the fourth optical unit 1350. The substrate 1360 can be disposed at a predetermined distance from the fourth optical unit 1350, and the substrate 1360 and the fourth optical unit 1350 can be disposed in a direction parallel to each other. The substrate 1360 can be disposed between the fourth optical unit 1350 and the fifth optical unit 1370. The substrate 1360 can include a first surface 1360a and a second surface 1360b. The first surface 1360a can be the surface of the substrate 1360 facing the fourth optical unit 1350, and the second surface 1360b can be the surface of the substrate 1360 facing the fifth optical unit 1370.

[0208] The substrate 1360 according to the embodiment may be a GaAs (Gallium Arsenide) substrate. The substrate 1360 may be a substrate that allows an optical signal to pass through. The substrate 1360 may have high optical transmittance because the optical signal must pass through it.

[0209] The fourth optical unit 1350 or the fifth optical unit 1370 may be disposed on one surface of the substrate 1360. The fourth optical unit 1350 may be disposed on the first surface 1360a of the substrate 1360, and the fifth optical unit 1370 may be disposed on the second surface 1360b of the substrate 1360.

[0210] At least one of the fourth optical unit 1350 or the fifth optical unit 1370 may be a metasurface disposed on one surface of the substrate 1360. The metasurface of the fourth optical unit 1350 or the fifth optical unit 1370 may be formed by etching the surface of the substrate 1360. The fourth optical unit 1350 or the fifth optical unit 1370 may be a metasurface etched on the first surface 1360a or the second surface 1360b of the substrate 1360.

[0211] Furthermore, the fourth optical unit 1350 or the fifth optical unit 1370 may be disposed as a coating on one surface of the substrate 1360. When the fourth optical unit 1350 or the fifth optical unit 1370 is disposed as a coating on one surface of the substrate 1360, the fourth optical unit 1350 or the fifth optical unit 1370 may be an optical element other than a metasurface. The fourth optical unit 1350 or the fifth optical unit 1370 may be an optical element coated on the first surface 1360a or the second surface 1360b of the substrate 1360.

[0212] The fifth optical unit 1370 can pass an optical signal that has passed through the substrate 1360. The fifth optical unit 1370 can be disposed at a predetermined distance from the substrate 1360, and the fifth optical unit 1370 can be disposed in a direction parallel to the substrate 1360. The fifth optical unit 1370 can be disposed between the substrate 1360 and the sixth optical unit 1380.

[0213] The fifth optical unit 1370 according to the embodiment can delay the phase of an optical signal by half a wavelength. The fifth optical unit 1370 can delay the phase of an optical signal that has passed through the substrate 1360 by half a wavelength. For example, the fifth optical unit 1370 can be a half-wave retardation wave plate.

[0214] According to the embodiment, the fifth optical unit 1370 may be a metasurface disposed on one surface of the substrate 1360. The fifth optical unit 1370 may be formed by etching the surface of the substrate 1360. The metasurface of the fifth optical unit 1370 may be an optical element that functions to delay the phase of an optical signal by half a wavelength in an ultrathin film form by arranging a plurality of nano-unit structures. When an optical signal passes through the metasurface, the phase of the optical signal may be delayed, thereby changing the path of the optical signal. When the metasurface is used, the total thickness of the plurality of optical elements may be reduced from several mm to 1 μm or less, thereby improving the performance of the optical module.

[0215] The fifth optical unit 1370 may be disposed on the second surface 1360b of the substrate 1360. The second surface 1360b may be disposed in a direction toward the sixth optical unit 1380 of the substrate 1360. The fifth optical unit 1370 may be a metasurface formed by etching the second surface 1360b of the substrate 1360. The fifth optical unit 1370 may be an optical element formed by coating the second surface 1360b of the substrate 1360.

[0216] The fifth optical unit 1370 according to the embodiment can reflect the first circularly polarized light of the optical signal and can pass the second circularly polarized light, which is obtained by delaying the phase of the first circularly polarized light by half a wavelength.

[0217] The first circularly polarized light may be the circularly polarized light of an optical signal whose phase is not delayed by half a wavelength, and the second circularly polarized light may be the circularly polarized light of an optical signal whose phase is delayed by half a wavelength after passing through the fifth optical unit 1370.

[0218] The sixth optical unit 1380 according to the embodiment can pass the optical signal that has passed through the fifth optical unit 1370. The sixth optical unit 1380 can be disposed at a predetermined distance from the fifth optical unit 1370, and the sixth optical unit 1380 can be disposed in a direction parallel to the fifth optical unit 1370. An observer can confirm the optical signal that has passed through the sixth optical unit 1380.

[0219] According to an embodiment, the sixth optical unit 1380 may be a linear polarizer that transmits the S-wave of the optical signal. The sixth optical unit 1380 may transmit only the S-wave polarized light of the optical signal that has passed through the fifth optical unit 1370, and may reflect the P-wave polarized light.

[0220] At least one of the fourth optical unit 1350 or the fifth optical unit 1370 according to the embodiment may be a metasurface disposed on one surface of the substrate 1360 .

[0221] One of the fourth optical unit 1350 or the fifth optical unit 1370 may be a metasurface disposed on one surface of the substrate 1360, in which case the other may be an optical element formed by coating on one surface of the substrate 1360. For example, the fourth optical unit 1350 may be a metasurface disposed on one surface of the substrate 1360 and focusing an optical signal, and the fifth optical unit 1370 may be an optical element disposed by coating on the other surface of the substrate 1360 and delaying the phase of the optical signal by half a wavelength. Also, for example, the fourth optical unit 1350 may be an optical element disposed by coating on one surface of the substrate 1360 and focusing an optical signal, and the fifth optical unit 1370 may be a metasurface disposed on the other surface of the substrate 1360 and delaying the phase of the optical signal by half a wavelength.

[0222] In this embodiment, the fourth optical unit 1350 may be a metasurface arranged on the surface of the substrate 1360 facing the third optical unit 1340, and the fifth optical unit 1370 may be a metasurface arranged on the surface of the substrate 1360 facing the sixth optical unit 1380.

[0223] The fourth optical unit 1350 and the fifth optical unit 1370 may be metasurfaces disposed on different surfaces of the substrate 1360. The fourth optical unit 1350 and the fifth optical unit 1370 may be disposed on two different surfaces spaced apart from each other on the path along which the optical signal passes through the substrate 1360.

[0224] The fourth optical unit 1350 may be disposed between the substrate 1360 and the third optical unit 1340. Alternatively, the fourth optical unit 1350 may be disposed parallel to the substrate 1360 or the third optical unit 1340, or may be disposed at a predetermined distance from each other. The fourth optical unit 1350 may be disposed at a predetermined distance from the third optical unit 1340, and the fourth optical unit 1350 may be a metasurface disposed on the surface of the substrate 1360 facing the third optical unit 1340. The fourth optical unit 1350 is formed on the surface of the substrate 1360 in a direction facing the third optical unit 1340, so that an optical signal passing through the third optical unit 1340 can pass through the metasurface of the fourth optical unit 1350.

[0225] The fifth optical unit 1370 may be disposed between the substrate 1360 and the sixth optical unit 1380. Alternatively, the fifth optical unit 1370 may be disposed parallel to the substrate 1360 or the sixth optical unit 1380, or may be disposed at a predetermined distance from each other. The fifth optical unit 1370 may be disposed at a predetermined distance from the sixth optical unit 1380, and the fifth optical unit 1370 may be a metasurface disposed on the surface of the substrate 1360 facing the sixth optical unit 1380. The fifth optical unit 1370 is formed on the surface of the substrate 1360 in a direction facing the sixth optical unit 1380, so that an optical signal passing through the metasurface of the fifth optical unit 1370 can pass through the sixth optical unit 1380.

[0226] The optical signal according to the embodiment may pass through the display unit 1310, the first optical unit 1320, the second optical unit 1330, the third optical unit 1340, the fourth optical unit 1350, and the substrate 1360 in sequence, then be reflected by the fifth optical unit 1370, pass through the substrate 1360 and the fourth optical unit 1350 in sequence, then be reflected by the third optical unit 1340, and pass through the fourth optical unit 1350, the substrate 1360, the fifth optical unit 1370, and the sixth optical unit 1380 in sequence.

[0227] The unit structure of the metasurface of the VR module according to the embodiment may be a cylindrical or rectangular prism.

[0228] The phase of an optical signal in a VR module according to an embodiment after passing through a metasurface can vary depending on the diameter of the unit structure.

[0229] The metasurface of the VR module according to the embodiment can be made of polymer, insulating or metallic materials.

[0230] The metasurfaces of the VR modules according to the embodiments can be isotropic, anisotropic, birefringent, polarization-dependent or polarization-independent structures.

[0231] FIG. 12 is a conceptual diagram of a VR module according to another embodiment.

[0232] Referring to FIG. 12, the VR module 1400 of the embodiment includes an optical system including a display unit 1410 that irradiates an optical signal and first to sixth optical units 1420, 1430, 1440, 1460, 1480, and 1490 that are sequentially arranged on the path of the optical signal, where the display unit 1410 and the first to sixth optical units 1420, 1430, 1440, 1460, 1480, and 1490 are arranged spaced apart from each other at a predetermined interval, and the fourth optical unit 1460 includes a first metasurface 1450 that focuses the optical signal and a second metasurface 1470 that faces the first metasurface 1450 and delays the phase of the optical signal by a quarter wavelength, and the fourth optical unit 1460 allows the optical signal irradiated from the display unit 1410 to pass through at least three times.

[0233] The display unit 1410 may emit an optical signal. The display unit 1410 may emit the optical signal to the first optical unit 1420. The display unit 1410 may be arranged along a first direction. The display unit 1410 may be a display panel that emits an optical signal and may output image information of the VR module. The display unit 1410 may include an LCD, an OLED, an OLEDoS, or a MicroLED.

[0234] The first to sixth optical units 1420, 1430, 1440, 1460, 1480, and 1490 may be optical elements that change the phase of an optical signal, such as a collimating lens, a diffractive optical element, a phase plate, a focusing lens, etc. The first to sixth optical units 1420, 1430, 1440, 1460, 1480, and 1490 may be arranged at predetermined intervals along a second direction perpendicular to the first direction on the path of an optical signal irradiated from the display unit 1410, and the first to sixth optical units 1420, 1430, 1440, 1460, 1480, and 1490 may be arranged in the same first direction as the display unit 1410. The first to sixth optical units 1420, 1430, 1440, 1460, 1480, and 1490 may be spaced apart at regular intervals or at different intervals. The spaces between the first to sixth optical units 1420, 1430, 1440, 1460, 1480, and 1490 are empty spaces, and air can act as an intermediate medium for optical signals. The first to sixth optical units 1420, 1430, 1440, 1460, 1480, and 1490 may be referred to as an optical system. Each of the first to sixth optical units 1420, 1430, 1440, 1460, 1480, and 1490 may be an optical element in the form of a thin film or a flat plate. In addition, the first to sixth optical units 1420, 1430, 1440, 1460, 1480, and 1490 are optical elements that have a certain thickness and are spaced apart, so a certain space is required to receive them. By including multiple optical units corresponding to the first to sixth optical units 1420, 1430, 1440, 1460, 1480, and 1490 in the optical system, it is possible to reduce the focal distance between the image of the VR module and the user.

[0235] The first optical unit 1420 can pass an optical signal emitted from the display unit 1410. The first optical unit 1420 can be spaced a predetermined distance from the display unit 1410, and the first optical unit 1420 can be arranged in a direction parallel to the display unit 1410. The first optical unit 1420 can be arranged between the display unit 1410 and the second optical unit 1430.

[0236] According to the embodiment, the first optical unit 1420 may be a linear polarizer that transmits the P wave of the optical signal. The first optical unit 1420 may transmit only the P wave polarized light of the optical signal irradiated from the display unit 1410 and reflect the S wave polarized light.

[0237] The second optical unit 1430 can pass the optical signal that has passed through the first optical unit 1420. The second optical unit 1430 can be disposed at a predetermined distance from the first optical unit 1420, and the second optical unit 1430 can be disposed in a direction parallel to the first optical unit 1420. The second optical unit 1430 can be disposed between the first optical unit 1420 and the third optical unit 1440.

[0238] According to an embodiment, the second optical unit 1430 may be a wave plate that delays the phase of the optical signal by a quarter wavelength. The second optical unit 1430 may delay the phase of the optical signal that has passed through the first optical unit 1420 by a quarter wavelength compared to the phase of the optical signal before passing through the first optical unit 1420.

[0239] According to an embodiment, the second optical portion 1430 may be a metasurface that delays the phase of the optical signal by a quarter wavelength.

[0240] The third optical unit 1440 can pass the optical signal that has passed through the second optical unit 1430. The third optical unit 1440 can be disposed at a predetermined distance from the second optical unit 1430, and the third optical unit 1440 can be disposed in a direction parallel to the second optical unit 1430. The third optical unit 1440 can be disposed between the second optical unit 1430 and the fourth optical unit 1460.

[0241] In this embodiment, the third optical unit 1440 may be a partially reflecting mirror that transmits 50% of the optical signal. The third optical unit 1440 may transmit 50% of the optical signal that has passed through the second optical unit 1430 and reflect the other 50%.

[0242] The fourth optical unit 1460 can pass the optical signal that has passed through the third optical unit 1440. The fourth optical unit 1460 can be disposed at a predetermined distance from the third optical unit 1440, and the fourth optical unit 1460 can be disposed in a direction parallel to the third optical unit 1440. The fourth optical unit 1460 can be disposed between the third optical unit 1440 and the fifth optical unit 1480.

[0243] The fourth optical unit 1460 in this embodiment includes a first metasurface 1450 that focuses the optical signal and a second metasurface 1470 that faces the first metasurface 1450 and delays the phase of the optical signal by a quarter wavelength, and the fourth optical unit 1460 can pass the optical signal irradiated from the display unit 1410 at least three times.

[0244] The fourth optical unit 1460 can pass an optical signal irradiated from the display unit 1410 at least three times. The fourth optical unit 1460 can pass an optical signal that has passed through the third optical unit 1440, can pass again an optical signal that has passed through the fourth optical unit 1460 and reflected to the fifth optical unit 1480, and can pass again an optical signal that has reflected to the third optical unit 1440.

[0245] According to an embodiment, the fourth optical unit 1460 may include GaAs (Gallium Arsenide). The fourth optical unit 1460 passes an optical signal irradiated from the display unit 1410, and therefore may have high transmittance for the optical signal.

[0246] The first metasurface 1450 and the second metasurface 1470 may be metasurfaces disposed on one surface of the fourth optical unit 1460. The first metasurface 1450 and the second metasurface 1470 may be formed by etching the surface of the fourth optical unit 1460. The first metasurface 1450 and the second metasurface 1470 may be formed by arranging a plurality of nano-unit structures to realize an optical element having a focusing function in an ultrathin film form. When an optical signal passes through the metasurface, the phase of the optical signal can be delayed to change the path of the optical signal. By using a metasurface, the total thickness of multiple optical elements can be reduced from several millimeters to less than 1 μm, thereby improving the performance of the optical module.

[0247] The first metasurface 1450 may be disposed on a first surface 1460a of the fourth optical unit 1460. The first surface 1460a may be a surface of the fourth optical unit 1460 disposed in a direction toward the third optical unit 1440. The first metasurface may be a metasurface formed by etching the first surface 1460a of the fourth optical unit 1460.

[0248] The first metasurface 1450 according to the embodiment can focus an optical signal. The first metasurface 1450 may be a metasurface that functions as a focusing lens that focuses an optical signal. When an optical signal that has passed through the third optical unit 1440 passes through the first metasurface 1450, it can be focused at a constant focal point.

[0249] The second metasurface 1470 may be disposed on the second surface 1460b of the fourth optical unit 1460. The second surface 1460b may be a surface of the fourth optical unit 1460 disposed in a direction toward the fifth optical unit 1480. The second metasurface 1470 may be a metasurface formed by etching the second surface 1460b of the fourth optical unit 1460.

[0250] According to the embodiment, second metasurface 1470 faces first metasurface 1450 and can delay the phase of an optical signal by a quarter wavelength. Second metasurface 1470 may be a metasurface that functions as a quarter wavelength retardation wave plate that delays the phase of an optical signal by a quarter wavelength. When an optical signal that has passed through fourth optical unit 1460 passes through second metasurface 1470, the wavelength may be delayed by a quarter wavelength. Second metasurface 1470 may be disposed on second surface 1460b that faces first surface 1460a on which first metasurface 1450 is disposed.

[0251] The fifth optical unit 1480 according to the embodiment can pass the optical signal that has passed through the fourth optical unit 1460. The fifth optical unit 1480 can be disposed at a predetermined distance from the fourth optical unit 1460, and the fifth optical unit 1480 can be disposed in a direction parallel to the fourth optical unit 1460.

[0252] According to an embodiment, the fifth optical unit 1480 may be a linear polarizer that reflects the P wave of the optical signal and transmits the S wave. The fifth optical unit 1480 may transmit only the S wave polarized light of the optical signal that has passed through the fourth optical unit 1460 and reflect the P wave polarized light.

[0253] The sixth optical unit 1490 according to the embodiment can pass the optical signal that has passed through the fifth optical unit 1480. The sixth optical unit 1490 can be disposed at a predetermined distance from the fifth optical unit 1480, and the sixth optical unit 1490 can be disposed in a direction parallel to the fifth optical unit 1480. An observer can confirm the optical signal that has passed through the sixth optical unit 1480.

[0254] The sixth optical unit 1490 according to the embodiment may be a linear polarizer that transmits the S-wave polarized light of the optical signal. The sixth optical unit 1490 may transmit the S-wave polarized light of the optical signal that has passed through the fifth optical unit 1480.

[0255] The optical signal according to the embodiment may sequentially pass through the display unit 1410, the first optical unit 1420, the second optical unit 1430, the third optical unit 1440, and the fourth optical unit 1460, then be reflected by the fifth optical unit 1480, pass through the fourth optical unit 1460, be reflected by the third optical unit 1440, and pass through the fourth optical unit 1460, the fifth optical unit 1480, and the sixth optical unit 1490, sequentially.

[0256] The unit structures of the metasurfaces according to the embodiments are cylindrical or rectangular prism-shaped, the phase of an optical signal after passing through the metasurface varies depending on the diameter of the unit structures, the metasurfaces are made of polymer, insulating or metallic materials, and the metasurfaces can be isotropic, anisotropic, birefringent, polarization-dependent or polarization-independent structures.

[0257] The VR module according to the embodiment may include a frame for externally fixing the display unit and the optical system, and a band for fixing the VR module to the observer.

[0258] The frame includes a display unit and an optical system, and the frame can fix the display unit and the optical system externally. The frame includes an opening through which an optical signal passing through the optical system can be incident on the viewer's eye. The frame can be configured in any shape and material that can protect the display unit and the optical system, and the type of shape and material is not limited.

[0259] The band can fix the VR module to the observer. The band can be connected to the outside of the frame of the VR module and fixed to the observer by wrapping around the observer's head. The band can be formed so that the opening of the frame is positioned at the observer's eye and the optical signal passing through the opening can be incident on the observer's eye. The length of the band that wraps around the observer's head can be adjusted, and the material and shape of the band are not limited.

[0260] The above description has focused on the embodiments, but these are merely examples and are not intended to limit the present invention. Those skilled in the art will recognize that various modifications and applications not exemplified above are possible within the scope of the essential characteristics of the present invention. For example, each component specifically illustrated in the embodiments can be modified and implemented. Differences related to such modifications and applications should be construed as being included within the scope of the present invention as defined in the appended claims.

Claims

1. substrate, a first electrode and a second electrode disposed separately on the substrate; a light emitting portion disposed on the first electrode and the second electrode, electrically connected to the first electrode and the second electrode, the light emitting portion including a first conductive type semiconductor layer, a light emitting layer, and a second conductive type semiconductor layer; a semiconductor substrate disposed on the light emitting portion, The semiconductor substrate is a first surface including a first region on which a metasurface is to be formed; and a second surface facing the first surface and in contact with the light emitting portion; the metasurface protrudes in a first direction from the second surface toward the first surface; A second region of the first surface excluding the first region where the metasurface is formed is flat, forming a light emitting device.

2. the light emitting unit includes a first opening for adjusting an area of ​​the optical signal emitted in the first direction; The light-emitting device according to claim 1 , wherein an area of ​​the first region where the metasurface is formed is larger than an area of ​​the first opening.

3. the metasurface comprises a plurality of unit structures; The light-emitting device according to claim 2 , wherein the phase of the optical signal is delayed by the plurality of unit structures.

4. The light emitting device of claim 3 , wherein the plurality of unit structures include a plurality of circular cylinders or a plurality of rectangular cylinders protruding from the first surface in the first direction.

5. The light-emitting device according to claim 3 , wherein the design of the unit structure is isotropic, anisotropic, birefringent, polarization-dependent or polarization-independent.

6. The light emitting device according to claim 1 , wherein the light emitting device is a vertical cavity surface emitting laser with a flip chip structure.

7. The light emitting device according to claim 1 , wherein the semiconductor substrate includes at least one of GaAs (Gallium Arsenide) and GaN (Gallium Nitride).

8. The light-emitting device according to claim 1 , wherein the metasurface is formed by MEMS (Micro Electro Mechanical Systems).

9. The light emitting device of claim 1 , wherein the metasurface performs at least one of focusing, divergence, and diffraction on an optical signal emitted from the light emitting portion.

10. a display unit that emits an optical signal; an optical system including first to sixth optical units sequentially arranged on a path of the optical signal; and a substrate disposed between the fourth optical unit and the fifth optical unit; the display unit and the first to sixth optical units are spaced apart from each other by a predetermined distance; the fourth optical unit focuses the optical signal; the fifth optical unit delays the phase of the optical signal; A VR (Virtual Reality) module, wherein at least one of the fourth optical unit or the fifth optical unit is a metasurface disposed on one surface of the substrate.

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