Optical Modules for Micro-LED Displays

Monolithic integration of light emitting structures that generate different colors of light on a single substrate. The technique involves growing light emitting structures, each with a laterally terminated active area, on a substrate with buffering layers made of GaN. The active areas of different structures emit different colors. A p-doped GaN layer covers each active area. This allows monolithic integration of red, green, and blue LEDs on a substrate for applications like displays. The GaN buffering layers enable epitaxial growth of high quality LED structures on the substrate.

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Micro-scale LED structure for high efficiency micro LED displays that allows for easy fabrication and packaging. The LED structure has a distributed Bragg reflector (DBR) in the insulation layer covering the LED sides. This reflects light back into the LED instead of leaking out. The DBR is thicker on the top surface than the sides to prevent uneven reflections. This improves efficiency by preventing side surface light escape. The DBR-coated LEDs are used in micro LED displays where the DBR-coated LEDs are subpixels in a unit pixel. The pixels are arranged on a transparent substrate with a light blocking layer to form the display.

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Integrated circuit components with glass interposers and micro-LEDs for high-speed, low-loss short-distance communication between integrated circuits. The components have micro-LED assemblies mounted directly on the IC dies and connected to waveguides in the glass interposer. This allows high-frequency signals to be sent/received optically through the glass interposer at close range without long copper traces. The micro-LEDs can operate at elevated temperatures and low energy levels.

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LED device and light-emitting apparatus with miniaturized LED chips for high resolution displays. The LED device has multiple LED chips, an electric circuit layer assembly, and an encapsulating layer. The encapsulating layer covers the LED chips and circuit assembly. This allows the LED chips to be defined into pixel sizes for high resolution displays. The LED devices can be arranged on a circuit board to make a compact light-emitting apparatus with high pixel density for display applications.

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Micro LED structure and display device with optical structures for improved light patterns in applications like augmented reality and virtual reality. The micro LED structure has multiple micro LED chips, each with a stacked semiconductor layer, metal pad, and reflective coating. Optical structures are placed over each micro LED chip. A planarization layer surrounds the micro LEDs. The optical structures enhance the light extraction efficiency from the micro LEDs for better AR/VR performance.

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Display device using micro-LEDs with improved brightness uniformity and reduced power consumption by surrounding the micro-LEDs with a scattering layer. The scattering layer surrounds the bonding layers connecting the micro-LEDs to the substrate. This prevents the micro-LEDs and scattering layer from overlapping when transferring the micro-LEDs, which can cause misalignment and uniformity issues. By surrounding the bonding layers with scattering, it extracts more light from the micro-LEDs and provides consistent brightness from all viewing angles.

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Abstract Micro lightemitting diodes (MicroLEDs) are regarded as the core of nextgeneration display technology due to their high brightness and energy efficiency. However, reduction in size MicroLEDs has led increased manufacturing challenges exacerbated issues such sidewall emission, which hinder development highpixeldensity displays. This paper proposes a vertically stacked MicroLED design based on an Lshaped metal wall structure, aiming suppress emission enhance top light extraction efficiency (LEE). Through parameter scanning, dimensions thickness epitaxial layer optimized. Combined with inclined sidewalls reflective structure wall, optical characteristics red, green, blue analyzed using raytracing simulations. The is significantly reduced (with maximum 68.04% compared without walls), enhanced (the LEE within 90 direction for blue, red by 196.18%, 51.69%, 3.45%, respectively, walls). simulation results demonstrate potential fullcolor displays, providing new approach suppressing crosstalk improving performance.

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Full-color monolithic InGaN micro-LEDs can achieve the transfer of full-color subpixels through a single flip-chip bonding process, offering advantages such as simplified fabrication processes and reduced production costs for micro-LED display. In this paper, we demonstrate structure that utilizes pseudo-quantum well to long-wavelength red emission, which is applied micro-LEDs. Subsequently, present micro-LEDs, stack (R), green (G), blue (B) epitaxial layers tunnel junctions. The entire grown epitaxially by metal organic chemical vapor deposition. Micro-LEDs with mesa size 2020 m 2 RGB are fabricated. exhibits emission peak wavelength 650 nm at an injection current density 1 A/cm , dominant approximately 620 nm, achieving true emission. Even under 100 it still maintain over 600 nm. broad color gamut coverage their significant potential applications in

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Display device with improved efficiency and contrast by using optimized nanostructures for light extraction from the wavelength conversion layers. The display has pixels with red, green, and blue subpixels. Each subpixel has a wavelength conversion layer and color filter. The nanostructures are arranged in periodic patterns matching the wavelengths converted by the conversion layers. This enhances light extraction efficiency by resonance and light localization effects near the nanostructures.

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MicroLED display with improved color conversion efficiency and reduced manufacturing cost. The display uses microLEDs with 3D structures on the emitting surface that extend into the device. Cavities are formed between the structures and filled with optical conversion material. This allows deeper cavity depths for better absorption/conversion of light. It also enables higher concentration of conversion material without thickness limitations. The microLEDs have regular 3D structures extending from the emitting surface into the device. These structures define cavities filled with optical conversion material for improved light absorption/conversion.

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Backlight module for displays that improves uniformity of light emission from micro LED arrays. The module uses feedback control to balance brightness across multiple micro LEDs driven by individual chips. Each micro LED has a shared positive terminal and a chip terminal connected to its negative terminal. Each chip has multiple control terminals, a feedback node per terminal, and a signal acquisition unit to collect feedback voltages. An adjustment module uses the feedback to balance brightness by adjusting chip control signals. This compensates for variability in micro LED currents due to differences in resistance.

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Abstract InGaN red micro-LEDs were fabricated with indium tin oxide (ITO) and metal n-electrode designs. Micro-LEDs ITO electrodes achieved a peak on-wafer external quantum efficiency of 2.1% (at 1.25 A/cm2) wall-plug 1.7% 0.64 A/cm2), representing 1.6 times 1.5 improvements compared to metal-based electrodes. Improved performance was attributed the transparency ITO, enabling light extraction, while block emission. Both configurations low leakage current density ( 107 high emission wavelength around 650 nm. These results represent strong potential for low-power consumption required/area-limited AR/VR applications.

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Anti-aliasing technique for microLED displays that improves image smoothness by adjusting brightness levels within individual pixels. The technique uses microLED displays with each pixel containing a group of three differently colored microLEDs covered by a scattering plate. By controlling the brightness of the individual microLEDs inside a pixel, it allows gradual color transitions between pixels for smoother images compared to using fixed color filters.

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Transferring micro-LEDs using a stamp with shape memory polymer nanotips to pick up and release the devices. The stamp has nanotips that can selectively adhere to the micro-LEDs due to shape memory properties. The nanotips heat to a critical temperature, contact the LED, press to attach, cool below critical temp, align on substrate, then heat again to transfer. This allows precise pickup, placement, and repair of micro-LEDs.

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Using microLED arrays in applications beyond just displays, like augmented reality (AR) and virtual reality (VR) devices, by integrating compact light sources made of microLED arrays into these devices. The microLED arrays provide smaller, more efficient light sources compared to traditional light sources. This allows for improved AR/VR devices with better display brightness, contrast, and power efficiency.

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MicroLED display to prevent crosstalk and improve brightness by inserting blocking regions between each color conversion region. The blocking regions prevent light from one subpixel leaking into adjacent subpixels, reducing crosstalk. This is achieved by forming the microLED structure with separate pores for the color conversion regions and additional blocking regions in between. The color conversion material is filled in the color conversion pores and the blocking regions are left empty. This prevents light from one subpixel leaking into adjacent subpixels, reducing crosstalk.

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An allGaNbased monolithic activematrix microLED system that integrates metalinsulatorsemiconductor highelectronmobility transistors (MIS HEMTs) with lightemitting diodes (LEDs) is demonstrated. The proposed structure employs direct electron injection from the 2D gas (2DEG) in a HEMT, serving as ntype layer, into quantum wells of LEDs. A 2HEMT1LED pixel configuration fabricated one epitaxial growth, enabling precise control LED light output through combination select and drive HEMTs. achieved maximum optical density 0.5 Wcm 2 . 2 matrix constructed row column lines connected via HEMTs, demonstrating capability for individual control.

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Abstract Microlight emitting diode (LED) based LED on silicon (LEDoS) is a promising candidate for nextgeneration AR and VR displays due to superior pixel performance potential high resolution. Traditional RGB pixels are placed single plane, which limits the To overcome this, vertically stacked using heterogeneous monolithic 3D integration (M3D) have been explored. However, previously reported vertical LED not considered heat dissipation capability of pixels, indeed important in future micro displays, utilized materials incompatible with standard CMOS processes, further limiting their practicality LEDoS. The critical regions constraint, bonding medium, typically organic polymer materials. Therefore, handle issue, fullcolor LEDs demonstrated oxide (SiO 2 ) yttrium (Y O 3 ), as mediums. These CMOScompatible offer thermal conductivity at least 10 times higher than conventional polymers. InGaN/GaN blue bonded oxides show improved management, leading external quantum efficiency (EQE) better color characteristics, including narrower full width half maximum (FWHM) purity. ... Read More

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Display apparatus with a pixel structure that allows combined light emission and light sensing in each subpixel. The pixel has subpixels, at least one of which has a light-emitting and light-receiving device instead of a regular light-emitting device. This allows the display to emit light and also detect light in the same subpixel. This enables multifunctionality like displaying an image and sensing light simultaneously. The light-emitting and light-receiving device has a structure with electrodes for emitting and sensing light.

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Display device with integrated components in the display area and an opening for other components. The display has a substrate with an opening surrounded by a display area. Grooves are formed between the opening and display using a layer with different etch selectivity compared to the main insulating layer. This allows etching grooves without damaging the display elements. It enables integrating components like sensors or cameras into the display while preventing contamination of the display area.

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A light-emitting element transfer stamp and manufacturing method for pickup and placement of micro-LEDs without complex spring structures or high voltages. The stamp has adhesive layers in grooves that protrude above the stamp. This allows selective picking up of micro-LEDs from a growth substrate by adhesion force, then releasing to transfer onto a target substrate. A passivation layer prevents sticking between layers. The stamp material has thermal expansion matching the LED substrate. The stamp has a buffer layer with thermal conductivity between the stamp and a heater wire. This enables local heating for stamp deformation and release of the LEDs. The stamp structure allows micro-LED transfer without complex springs or high voltages.

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Packaging design for optical interconnects that allows vertical transmission between stacked optical components using integrated lenses and reflectors. The packaging involves bonding optical interposers and optical packages vertically aligned with lenses between them. The reflectors in each interposer are aligned vertically to transmit light between the packages. This enables vertical optical transmission between stacked optical components using integrated lenses and reflectors instead of through-the-substrate techniques.

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Arrangement and method for simplified assembly of compact optoelectronic devices like microLED displays with improved uniformity and reduced tilt. The devices have small-sized semiconductor components with side walls insulated and absorbing to prevent tilt. They are mounted on a carrier with a transparent output element and connected via an insulating layer. The components' contacts are electrically accessed from the rear. This allows easier assembly of small-pitch arrays with uniform radiation and reduced crosstalk. The method involves applying the components, insulation, and output element on a carrier, then connecting the contacts.

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Micro LED display panel design to improve display quality by reducing aberrations and crosstalk between subpixels. The key idea is to surround the LED chip with a symmetrical void in the prism layer. This ensures equal distances between the LED and void in the transverse and oblique directions. The symmetry allows the light rays to reflect identically in both directions, preventing asymmetric focal planes and reducing astigmatism. It also prevents light crosstalk between subpixels by reflecting the rays back into the LED instead of spreading them.

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Light emitting module with reduced stray light on the irradiation surface. The module has a lens over the light source, and a cover over the lens. The cover has three regions: an inner region where light from the lens enters, a middle region around the inner region with higher diffusion, and an outer region. This configuration reduces stray light by having the cover's middle region with higher diffusion surrounding the inner region where light from the lens enters, preventing light from escaping sideways.

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Micro LED display panel with integrated micro lenses to simplify manufacturing. Each micro LED structure has a first type epitaxial layer, a light emitting layer, and a second type epitaxial layer. The second type epitaxial layer has an integrated structure containing both a micro lens and a bottom layer. This eliminates the need for a separate micro lens manufacturing step.

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An optical laminate with improved light extraction. The laminate has a light extraction layer with recessed areas, covered by two sheets separated by adhesive. The recessed areas form air gaps between the sheets. The laminate also optionally has a thin porous layer between the light extraction layer and the adhesive. The air gaps and porous layer lower the refractive index in certain regions, improving light extraction compared to solid adhesive.

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Transparent display device with improved resolution and repair capability. The display has sub-pixels containing red, green, and blue LEDs, along with a reserve sub-pixel with stacked red, green, and blue LEDs. If any LED in a normal sub-pixel fails, the reserve LEDs can replace them. Stacking the reserve LEDs reduces area compared to parallel LEDs. The reserve LED electrodes are transparent to allow light from lower LEDs to escape. This allows repair and area savings while maintaining light output.

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Optical stack and backlight design for high dynamic range displays using blue LEDs instead of white backlights. The optical stack reflects blue light with a specific polarization and transmits orthogonal polarization. This allows collimated blue light with low divergence to be used in displays with blue-only backlights. The stack has high reflection in the blue range for one polarization and high transmission for the orthogonal polarization. This preserves blue light while suppressing cross-talk between pixels in blue-only displays. The collimated blue light can be generated by blue LEDs and reduces the need for color filters in the display.

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MicroLED displays with containers for color conversion materials like quantum dots that have varying diameter profiles along their length. This shape provides better light coupling efficiency compared to cylindrical containers. The containers have a waist section with a smaller diameter than the end faces. This design helps collect more emitted light from the LED into the display's acceptance angle. It balances couplings between LED, quantum dots, microlens, and display acceptance cone for improved overall display performance.

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Display module with micro-lenses to improve brightness of microLED displays. The display module has a color filter layer with light-filtering sections, and a micro-lens layer with converging lenses. Each micro-lens is aligned with a color filter section. Gaps are provided between adjacent micro-lenses. Additional converging lenses are placed in these gaps to capture light from the gaps and focus it. This improves brightness by reducing light spread and improving convergence.

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A miniaturized, high efficiency planar light source device for displays like head-up displays (HUD) and mini projectors. The device uses an LED as the light source and a collimating optical system to convert the LED light into parallel beams. The collimator has a reflective film that reflects blue and UV light back to the LED. This increases LED utilization. A polarization conversion element aligns the polarization of the collimated light. In displays, this aligned collimated light is incident on a liquid crystal panel with a preferred polarization axis. This allows compactness and high efficiency compared to conventional LED+collimator+diffuser setups.

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Using microLEDs as short-range optical interconnects between chips in a package to replace electrical connections. MicroLEDs on chips emit light that is guided through waveguides to photodetectors on other chips. This provides high-speed, low-power, and low-latency optical communication within packages that overcomes the limitations of electrical interconnects at short distances. The microLEDs are small enough to integrate on chips and their broad spectral output is suitable for waveguide transmission. The use of microLEDs instead of lasers allows compact, temperature-insensitive, and efficient optical interconnects for chip-to-chip communications.

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Monolithic microLED display with integrated color conversion for high resolution, efficiency, and brightness. The display has monochrome microLEDs emitting a primary color (e.g., blue) with additional color conversion pixels adjacent to each monochrome pixel. The color conversion pixels contain quantum dots that emit a different color when excited by the primary light. This allows full-color displays using monochrome microLED arrays. The quantum dots are added in a separate process outside of high-resolution semiconductor fabrication. The key is placing the conversion pixels precisely adjacent to each monochrome pixel using high-resolution lithography.

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Compact transparent display that combines substrate guided optics (SGO) and switchable Bragg gratings (SBGs) to achieve high resolution, wide field of view, and compact size. The display has two optical substrates with waveguides and gratings to extract light. The SGO waveguides propagate light in one direction, while the SBG gratings extract light perpendicularly. This allows dividing the input image into angular intervals and time sequentially displaying them for a unified image. The SBGs can be passive or switching for color. The compactness comes from using thin SBGs with wide angular bandwidths instead of stacking multiple gratings.

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A compact photo detecting device with integrated light sources that allows downsizing and customization of wavelengths compared to separate light sources and sensors. The device has photoelectric conversion elements on a substrate to detect light, integrated light emitting elements on the same substrate, and a control circuit to set the light emitting elements' wavelengths by adjusting current. This allows integrated light sources and sensors on the same substrate with tunable wavelengths.

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An optical module for a display that reduces power consumption while maintaining color accuracy. The module has two panels emitting blue and green light, with lower current green emitters. A prism combines the blue and green light. The green panel has lower voltage difference between supply wires than the blue panel. This allows using lower current green emitters to match brightness. The blue panel has higher voltage difference. The prism combines the blue and green light to synthesize white. By optimizing voltage differences for panels with different emitters, it reduces power without sacrificing color balance.

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A method for manufacturing optoelectronic devices like displays and projectors with arrays of diodes covered by photoluminescent conversion layers. The method involves depositing an electret layer with surface potential patterns defined by localized depolarization or polarization using light. This allows accurate placement of photoluminescent particles on the patterns during dielectrophoresis to form the conversion pads. It enables precise alignment of the pads with the diodes in arrays with small pixel pitches without alignment issues.

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Compact light source module with integrated merging of multiple colored light beams without the need for complex directional couplers. The module has three separate LEDs emitting red, green, and blue light. The light beams are guided through a core inside a cladding. The core has three separate waveguides for each LED, a merging point where two waveguides combine, and a final merging point where all three waveguides combine. This allows the colored light beams to merge and exit together through a single emission point. The core geometry and merging points are designed to efficiently combine the beams without loss.

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Light emitting device with improved light utilization for displays and lighting applications. The device has a light emitting element on a substrate with a microlens fixed to the substrate over the light emission region. The microlens center overlaps the light emission center in plan view. This configuration focuses light from the edge of the emission region more than the center, reducing light waste in oblique directions. For displays, it improves light utilization at peripheral pixels where oblique light is needed. For lighting, it improves utilization at oblique angles.

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Wafer level microstructures for an optical lens that provide diffractive functionality, anti-reflective properties, and protection. The lens has a substrate with diffractive microstructures formed on one surface using a separate material with optimized refractive indices. This prevents damage and contamination compared to exposed microstructures. A protective layer covers the microstructures. Anti-reflective coatings are also applied to the substrate surfaces and protective layers to further reduce reflections.

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Light emitting device with optimized number of light-guiding units for improved efficiency and brightness. The device has a light emitting panel with sub-pixels, and a light guiding structure overlaying the panel. The sub-pixels have different areas. The light guiding structure has more units covering the larger sub-pixel than the smaller sub-pixel. This optimizes light extraction and efficiency by focusing more light guiding resources on the sub-pixel with higher light output potential.

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Display device with integrated optical components to prevent light degradation when optical elements are placed directly on the display screen. The display has a substrate with a display area and a transmissive area. An optical device overlaps the display area. Blocking layers are placed on the display area surfaces near the optical device to prevent light leakage around the optical element. This prevents light from entering the blocked areas and degrading display quality.

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Light-emitting substrate, light-emitting module, and display device with improved brightness uniformity and reduced cost compared to conventional designs. The light-emitting substrate has an array of light-emitting assemblies, each containing a light-emitting element surrounded by a light adjustment portion with multiple spaced sub-structures. The sub-structures nearer the element have shorter height than farther sub-structures. This provides localized light spreading and reduces brightness variations between adjacent elements. The design reduces the need for dense element packing and high angle elements, improving uniformity and cost compared to dense element arrays. The light-emitting module further has lenses matching the sub-structure shapes to further enhance uniformity. The display device can use these modules with higher brightness and uniformity.

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Display device with improved brightness and color accuracy by using irregularly spaced micro LED arrays in subpixels. The subpixels contain multiple micro LEDs instead of just one. The micro LEDs are arranged in an irregular pattern within the subpixel area. This allows more micro LEDs to fit in the subpixel, increasing overall brightness. The irregular layout also helps balance brightness across subpixels since the micro LED count compensates for differences in micro LED efficiency. The micro LEDs can be different colors, with color conversion elements as needed.

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A light source module for displays, particularly for high-density applications like automotive displays, with improved reliability and assembly tolerance. The module has a separator above the light board with intersecting ribs forming spaces for the LEDs. The inner walls of the ribs recess away from the LED board further than closer to the board. This prevents collisions during assembly when the separator is lowered onto the board. The recessed walls also provide clearance for the LEDs.

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Light emitting panel with improved forward light extraction efficiency. The panel has a substrate, light emitting units on the substrate, a diffuse reflective layer over the substrate with openings matching the light emitting units, and an encapsulating adhesive layer covering the components. The adhesive thickness on the diffuse reflective layer is greater than 40 microns. This larger adhesive thickness on the reflective layer helps redirect light internally reflected by the diffuser back towards the front instead of escaping from the sides.

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An optical coupling structure for coupling a microLED array to an optical fiber to improve optical coupling efficiency. The structure has an alignment layer, growth substrate, and optical functional layer stacked. The growth substrate is used to grow the optical functional layer containing the microLEDs. It has a through hole aligned with the microLEDs. The alignment layer has a through hole for the fiber input end. An embedding structure connects the through holes and clamps the layers. This aligns the microLEDs with the fiber and prevents damage to the fragile microLEDs when bonding the fiber.

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Micro display module with integrated micro LED panels and X-cube prism for compactness and improved efficiency compared to separate panels. The micro display has multiple micro LED panels directly attached to surfaces of the X-cube prism that combines their monochrome light into full color. This eliminates the need for a cage to align the panels with the prism, reducing volume and optical loss compared to separate panels. The micro LEDs are on flexible boards with connectors for easy attachment to the prism.

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An optical module design to improve thermal management and reduce material waste compared to conventional optical modules. The module has a housing with a circuit board inside. The circuit board has components like the driving chip and silicon optical chip attached to its top surface. A laser emitting light is attached to the side of the silicon chip away from the circuit board. A light guide device directs the laser light into the silicon chip. This allows the optical components to be positioned closer together without needing a separate heat sink. The circuit board can have shorter gold wire connections for the silicon chip since it's attached directly. This reduces material waste compared to excavating a separate groove for the heat sink. The compact layout and integrated light guide help with thermal management by minimizing heat transfer distances and allowing better heat dissipation from the circuit board.

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