Abstract: An optoelectronic semiconductor part comprising a light source, a housing and electrical connections, wherein the optoelectronic semiconductor part comprises a component which contains metal phosphate, and wherein the metal phosphate is substantially alkali-free and halogen-free.

Abstract: According to one embodiment, a light emitting device includes a substrate, a first electrode, a second electrode, an insulating section, a light emitting section, and a third electrode. The substrate with a groove is provided at a surface. The first electrode is provided inside the groove. The second electrode is provided on the substrate and the first electrode. The insulating section is provided on the second electrode. The light emitting section is provided on the second electrode and the insulating section. The third electrode is provided on the light emitting section. The first electrode has a side surface inclined away from a portion of the light emitting section provided on the second electrode toward bottom portion side of the groove.

Abstract: Provided is a white LED including a reflector cup; an LED chip mounted on the bottom surface of the reflector cup; transparent resin surrounding the LED chip; a phosphor layer formed on the transparent resin; and a light transmitting layer that is inserted into the surface of the phosphor layer so as to form an embossing pattern on the surface, the light transmitting layer transmitting light, incident from the phosphor layer, in the upward direction.

Abstract: Provided are a light emitting device, a method of manufacturing the light emitting device, a light emitting device package, and a lighting system. The light emitting device includes a reflective layer including a first GaN-based semiconductor layer having a first refractive index, a second GaN-based semiconductor layer having a second refractive index less than the first refractive index, and a third GaN-based semiconductor layer having a third refractive index less than the second refractive index and a light emitting structure layer including a first conductive type semiconductor layer, a second conductive type semiconductor layer, and an active layer disposed between the first conductive type semiconductor layer and the second conductive type semiconductor layer on the reflective layer.

Abstract: Disclosed is an LED package. The LED package includes a package body, a first frame and a second frame on the package body and a light emitting device chip on the first frame. The first frame is separated from the second frame, and the first frame includes a bottom frame on the package body and at least two sidewall frames extending from the bottom frame and inclined with respect to the bottom frame.

Abstract: A light emitting device according to the embodiment includes a first light emitting structure including a first conductive type first semiconductor layer, a first active layer under the first conductive type first semiconductor layer, and a second conductive type second semiconductor layer under the first active layer; a first reflective electrode under the first light emitting structure; a second light emitting structure including a first conductive type third semiconductor layer, a second active layer under the first conductive type third semiconductor layer, and a second conductive type fourth semiconductor layer under the second active layer; a second reflective electrode under the second light emitting structure; a contact part that electrically connects the first conductive type first semiconductor layer of the first light emitting structure to the second reflective electrode; and a first insulating ion implantation layer between the contact part and the second conductive type second semiconductor layer

Abstract: A multi-layer substrate for a vertical light-emitting diode (LED) includes a conductive and reflective base substrate and an n-type gallium nitride (GaN) layer formed on the base substrate.

Abstract: A light-reflective anisotropic conductive adhesive and light-emitting device capable of maintaining luminous efficiency of a light-emitting element and preventing the occurrence of a crack to obtain conduction reliability are provided. The light-reflective anisotropic conductive adhesive contains a thermosetting resin composite, conductive particles, and a light-reflective acicular insulating particles. These light-reflective acicular insulating particles are inorganic particles of at least one type selected from the group including titanium oxide, zinc oxide, and titanate.

Abstract: A light emitting device according to the embodiment includes a support substrate; a first light emitting structure disposed on the support substrate and including a first conductive type first semiconductor layer, a first active layer, and a second conductive type second semiconductor layer; a first reflective electrode under the first light emitting structure; a first metal layer around the first reflective electrode; a second light emitting structure disposed on the support substrate and including a first conductive type third semiconductor layer, a second active layer, and a second conductive type fourth semiconductor layer; a second reflective electrode under the second light emitting structure; a second metal layer around the second reflective electrode; and a contact part making contact with an inner portion of the first conductive type first semiconductor layer of the first light emitting structure and electrically connected to the second reflective electrode.

Abstract: Disclosed are a light emitting device package and a lighting system. The light emitting device package includes a body including a cavity, at least one light emitting device in the cavity, a resin member filled in the cavity while covering the light emitting device, and a reflective layer on a lateral side of the cavity. The reflective layer is formed while opening the upper region of the cavity. The reflective layer is selectively formed only in a lower region of the lateral side of the cavity in the body, and the resin member, which is filled in the upper portion of the cavity, directly adheres to the body. The air-tightness between the resin member and the body is improved.

Abstract: The present disclosure relates to a compound semiconductor light-emitting element comprising: a frame; an adhesive provided on the frame; a light-emitting part which is secured in position on the frame by means of the adhesive and which includes a substrate, a first compound semiconductor layer formed on the substrate and having a first type of conductivity, a second compound semiconductor layer having a second type of conductivity that is different from the first type of conductivity, and an active layer disposed between the first compound semiconductor layer and the second compound semiconductor layer to generate light via electron-hole recombination; and a spacer disposed between the light-emitting part and the frame to create a gap therebetween.

Abstract: A nitride semiconductor light-emitting device includes a nitride semiconductor light-emitting element, a package substrate and an optically transparent resin sealing portion. The nitride semiconductor light-emitting element includes a substrate, a nitride semiconductor multilayer portion having a light-emitting layer and a protective layer. The nitride semiconductor multilayer portion is provided on the substrate. The protective layer is provided on an upper portion of the nitride semiconductor multilayer portion. The resin sealing portion seals the nitride semiconductor light-emitting element that is mounted on the package substrate. An air gap layer is formed in at least one of an area between the substrate and the light-emitting layer in the nitride semiconductor light-emitting element, an area between the light-emitting layer and the protective layer in the nitride semiconductor light-emitting element and an area in the package substrate.

Abstract: An LED module A1 includes a first lead 1 with a mount surface 12a at a die-bonding portion 12, a second lead 2 with a wire-bonding portion 22 and having a thickness direction corresponding to that of the lead 1, and an LED chip 3 on the mount surface 12a, with a first electrode terminal 31 connected to the first lead 1, and a second electrode terminal 32 connected to the second lead 2. A support member 4 supports the leads 1, 2, The second terminal 32 is on a thickness-side surface of the LED chip 3 and connected to the wire-bonding portico 22 with a wire 61. The support member 4 includes a protective portion 42 covering a thickness-side surface of the first lead 1 with the mount surface 12a exposed. The die-bonding portion 12 bulges, in the thickness direction, relative to portions of the first lead 1 covered by the protective portion 42. The arrangements provide a longer lifetime and ensures reliability and proper light emission.

Abstract: Disclosed are a light emitting device package and a lighting system including the same. The light emitting device package includes a first lead frame and a second lead frame disposed on an insulating layer and electrically separated from each other by a separation part, and a light emitting device disposed on the second lead frame and electrically connected to the first lead frame, and the second lead frame includes a through part disposed opposite to the separation part such that the light emitting device is located therebetween.

Abstract: A semiconductor light emitting device includes a semiconductor structure, a transparent electrically-conducting layer, a dielectric film, and a metal reflecting layer. The semiconductor structure includes an active region. The transparent electrically-conducting layer is formed on the upper surface of the semiconductor structure. The dielectric film is formed on the upper surface of the transparent electrically-conducting layer. The metal reflecting layer is formed on the upper surface of the dielectric film. The dielectric film has at least one opening whereby partially exposing the transparent electrically-conducting layer. The transparent electrically-conducting layer is electrically connected to the metal reflecting layer through the opening. A barrier layer is partially formed and covers the opening so that the barrier layer is interposed between the transparent electrically-conducting layer and the metal reflecting layer.

Abstract: Embodiments disclose a light emitting device package including an insulating layer, a first lead frame and a second lead frame disposed on the insulating layer electrically separate from each other, a light emitting device disposed on the second lead frame electrically connected to the first lead frame and the second lead frame, the light emitting device includes a light emitting structure having a first conduction type semiconductor layer, an active layer, and a second conduction type semiconductor layer and a lens which encloses the light emitting device, wherein the insulating layer has an end portion projected beyond at least one of an end portion of the first lead frame and an end portion of the second lead frame, to form an opened region which exposes the insulating layer.

Abstract: A photoelectric device includes a ceramic substrate defining a cavity in a top thereof and having two electrode layers beside the cavity. A photoelectric die is received in the cavity. A first packing layer is received in the cavity and encapsulates the photoelectric die. The photoelectric die is electrically connected with the electrode layers via two wires. A reflective cup is mounted on the ceramic substrate and defines a receiving space above the top of the ceramic substrate and the first packing layer. A second packing layer is received in the receiving space and covers the first packing layer.

Abstract: A semiconductor light-emitting device (A) having a simple configuration whereby it is possible to easily and accurately confirm whether or not ultraviolet light is being emitted, the semiconductor light-emitting device comprising: a semiconductor light-emitting element (1) for emitting ultraviolet light in an ultraviolet or deep ultraviolet region; a cap part (6) having a through-hole (63) in the top part through which ultraviolet light passes and encircling the semiconductor light-emitting element (1); a translucent cover (7) for transmitting ultraviolet light, the translucent cover being disposed so as to hermetically close up the through-hole (63); and a UV-excited phosphor (8) which is excited by ultraviolet light and which emits visible light, the UV-excited phosphor being disposed inside the cap part (6).

Abstract: An LED module A1 is provided with: a first lead 1 including a die-bonding portion 12 with a mount surface 12a, and a front-end sunk portion 14; a second lead 2 including a wire-bonding portion 22 and spaced apart from the first lead 1; an LED chip 3 mounted on the mount surface 12a and provided with a first electrode terminal 31 and a second electrode terminal 32; a wire 61 connecting the second electrode terminal 32 and the wire-bonding portion 22; and a support member 4 including a protective portion 42 and supporting the leads 1 and 2. The protective portion covers the front-end sunk portion 14 with the mount surface 12a exposed, and includes an inclined portion 42a that becomes thinner as proceeding from the die-bonding portion 12 toward the lead 2. The arrangements provide a longer lifetime and ensures reliability and proper light emission.

Abstract: A light emitting diode (LED) package including a carrier, at least one LED chip, and a light guide element is provided. The LED chip is disposed on the carrier. The light guide element including a light transmissive body, a light integration part, a reflective film, and a support part is disposed on the carrier and above the LED chip. The light integration part connected to the light transmissive body and disposed between the light transmissive body and the LED chip has a light incident surface facing the LED chip and at least one side. The side connects the light transmissive body and the light incident surface. The reflective film is disposed on the side. The support part leaning on the carrier is connected to the light transmissive body and surrounds the light integration part. The light transmissive body, the light integration part, and the support part are integrally formed.

Abstract: A light emitting device (100) includes a base member (101), electrically conductive members (102a, 102b) disposed on the base member (101), a light emitting element (104) mounted on the electrically conductive members (102a, 102b), an insulating filler (114) covering at least a portion of surfaces of the electrically conductive members (102a, 102b) where the light emitting element (104) is not mounted, and a light transmissive member (108) covering the light emitting element (104).

Abstract: An array substrate for a transflective liquid crystal display device includes: a substrate; a gate line and a data line on the substrate, the gate line and the data line crossing each other to define a pixel region including a transmissive area and a reflective area surrounding the transmissive area; a thin film transistor having a gate insulating layer, the thin film transistor electrically connected to the gate line and the data line; a first passivation layer having a drain contact hole exposing a drain electrode of the thin film transistor and a through hole exposing the substrate in the transmissive area; a pixel electrode on the first passivation layer, the pixel electrode contacting the substrate in the transmissive area through the through hole; and a reflective plate on the pixel electrode, the reflective plate being electrically connected to the drain electrode through the drain contact hole and to the pixel electrode.

Abstract: An X-raydetector (1) is proposed comprising a light detection arrangement (3) such as a CMOS photodetector, a scintillator layer (5) such as a CsI:T1 layer, a reflector layer (9) and a light emission layer (7) interposed between the scintillator layer (5) and the reflector layer (9). The light emission layer (7) may comprise an OLED and may be made with a thickness of less than 50 ?m. Thereby, a sensitivity and resolution of the X-raydetector may be improved.

Abstract: A package for a light source is disclosed. In particular, a Plastic Leaded Chip Carrier (PLCC) is described which provides many features offered by traditional surface mount technology lamps, but also has a decreased height, increased light output, and enables a smaller viewing angle as compared to traditional surface mount technology lamps.

Abstract: A semiconductor light-emitting device and a method for manufacturing the same can include a wavelength converting layer encapsulating at least one semiconductor light-emitting chip to emit various colored lights including white light. The semiconductor light-emitting device can include a base board with the chip mounted thereon, a frame located on the base board, a transparent plate located on the wavelength converting layer, a reflective material layer disposed between the frame and both side surfaces of the wavelength converting layer and the transparent plate, and a light-absorbing layer located on the reflective material layer. The semiconductor light-emitting device can be configured to improve light-emitting efficiency and a contrast between a light-emitting and non-light-emitting surfaces by using the transparent material and light-absorbing layer.

Abstract: There are provided a light emitting device package and a method of manufacturing the same. The light emitting device package includes a body part including a through hole formed in a thickness direction; at least one light emitting device disposed within the through hole; and a wavelength conversion part filling the through hole and supporting the light emitting device.

Abstract: An LED array includes a substrate, protrusions formed on a top surface of the substrate, and LEDs formed on the top surface of the substrate and located at a top of the protrusions. The LEDs are electrically connected with each other. Each LED includes a connecting layer, an n-type GaN layer, an active layer, and a p-type GaN layer formed on a top of the protrusions in sequence. A bottom surface of the n-type GaN layer connecting the connecting layer has a roughened exposed portion. The bottom surface of the n-type GaN layer has an N-face polarity.

Abstract: A light emitting diode (LED) package and a manufacturing method thereof are provided. The LED package includes a substrate including a circuit layer, an LED mounted on the substrate, and a plurality of protruded reflection units disposed in a region excluding an LED mounting region on the substrate and configured to reflect light generated from the LED.

Abstract: A light-emitting device which has various emission colors and can be manufactured efficiently and easily is provided. A first conductive layer formed of a semi-transmissive and semi-reflective conductive film is provided in a first light-emitting element region, so that the intensity of light in a specific wavelength region is increased with a cavity effect. As a result, the light-emitting device as a whole can emit desired light. When the first conductive layer is formed using a material with low electric resistance, voltage drop in a transparent conductive layer in the light-emitting device can be prevented. Accordingly, a light-emitting device with less emission unevenness can be manufactured. By applying such a structure to a white-light-emitting device, desired white light emission or white light emission with an excellent color rendering property can be obtained. Further, a large-area lighting device including a white-light-emitting device with less emission unevenness can be provided.

Abstract: A light-emitting chip (22) includes: a container (30) having a concave portion (31); first to fourth lead portions (61) to (64), provided to be exposed to the concave portion (31); and a first blue LED to a fourth blue LED (74) mounted on the first to fourth lead portions (61) to (64) exposed to the concave portion (31). The container (30) includes a first container portion (40) covering the region of the concave portion (31) where the first to fourth lead portions (61) to (64) are not exposed, and a second container portion (50) contacting the first to fourth lead portions (61) to (64) without being exposed to the concave portion (31) and accommodating the first container portion (40). The first container portion (40) is formed of a material having higher light reflectivity than that of the second container portion (50), and the second container portion (50) is formed of a material having higher thermal conductivity than that of the first container portion (40).

Abstract: An apparatus and method of a lamp including an optically transmitting, thermally conductive substrate is provided. The substrate has a first side, a second side, and at least one edge. At least one solid state light source, such as but not limited to a light emitting diode, is disposed on the first side of the substrate. The at least one solid state light source (e.g., light emitting diode) includes at least one junction having a first junction temperature. The substrate used is an optically transmitting, thermally conductive substrate, with a thermal conductivity greater than or equal to about 3 W/mK.

Abstract: A light-emitting diode housing comprising fluoropolymer is disclosed. The light-emitting diode housing supports a light-emitting diode chip and reflects at least a portion of the light emitted from the light-emitting diode chip.

Abstract: A light emitting device includes: a substrate; an n layer; an active light emitting region, a p layer; and a support portion configured to provide both mechanical support and improve light transmission disposed over a light emitting side of the device.

Abstract: A surface-mount light emitting device is provided comprising a light emitting element (2), a reflector (1) which is molded integral with a leadframe (11, 12) having the light emitting element mounted thereon, and an encapsulating resin composition (4). The reflector is molded from a heat curable resin composition to define a recess with bottom and side walls. The resin side wall has a thickness of 50-500 ?m. The encapsulating resin composition is a heat curable resin composition having a hardness of 30-70 Shore D units in the cured state.

Abstract: A solid state lighting device includes a device-scale stamped heatsink with a base portion and multiple segments or sidewalls projecting outward from the base portion, and dissipates all steady state thermal load of a solid state emitter to an ambient air environment. The heatsink is in thermal communication with one or more solid state emitters, and may define a cup-like cavity containing a reflector. At least a portion of each one sidewall portion or segment extends in a direction non-parallel to the base portion. A dielectric layer and at least one electrical trace may be deposited over a metallic sheet to form a composite sheet, and the composite sheet may be processed by stamping and/or progressive die shaping to form a heatsink with integral circuitry. At least some segments of a heatsink may be arranged to structurally support a lens and/or reflector associated with a solid state lighting device.

Abstract: A solid state emitter package may include at least one electrically conductive path associated with the solid state emitter package that is not in electrical communication with any solid state emitter of the solid state emitter package, with such electrically conductive path being susceptible to inclusion of a jumper or a control element. A solid state emitter package includes a principally red solid state emitter having peak emissions within 590 nm to 680 nm, a principally blue solid state emitter having peak emissions within 400 nm to 480 nm, and at least one of a common leadframe, common substrate, and common reflector, with the package being devoid of any principally green solid state emitters having peak emissions between 510 nm and 575 nm.

Abstract: A light-emitting device manufacturing method comprises the steps of irradiating a substrate 2 having a III-V compound semiconductor layer 17 formed on a front face 2a with laser light L1 along lines to cut 5a, 5b, while locating a converging point P1 within the sapphire substrate 2 and using a rear face 2b thereof as a laser light entrance surface, and thereby forming modified regions 7a, 7b along the lines 5a, 5b within the substrate 2; then forming a light-reflecting layer on the rear face 2b of the substrate 2; and thereafter extending fractures generated from the modified regions 7a, 7b acting as a start point in the thickness direction of the substrate 2, and thereby cutting the substrate 2, the semiconductor layer 17 and the light-reflecting layer along the lines 5a, 5b, and manufacturing a light-emitting device.

Abstract: A light emitting device according to the embodiment includes a first electrode; a light emitting structure including a first semiconductor layer over the first electrode, an active layer over the first semiconductor layer, and a second semiconductor layer over the second semiconductor layer; a second electrode over the second semiconductor layer; and a connection member having one end making contact with the first semiconductor layer and the other end making contact with the second semiconductor layer to form a schottky contact with respect to one of the first and second semiconductor layers.

Abstract: A fluorescent substrate (5) of the present invention includes: a fluorescent layer (3) which emits light by receiving excitation light; and a reflecting film (10) being provided both (i) on a side surface(s) of the fluorescent layer (3) and (ii) on a surface of the fluorescent layer (3), on which surface the excitation light is incident, the reflecting film (10) (I) transmitting a component having a peak wavelength of the excitation light, and (II) reflecting a component having a peak wavelength of the light emitted from the fluorescent layer (3).

Abstract: A semiconductor light-emitting element includes a support substrate, a semiconductor film including a light-emitting layer provided on the support substrate, a surface electrode provided on a light-extraction-surface-side surface of the semiconductor film, and a light-reflecting layer provided between the support substrate and the semiconductor film, forming a light-reflecting surface. The surface electrode includes a first electrode piece and a second electrode piece. The light-reflecting layer includes a reflection electrode including a third electrode piece and a fourth electrode piece. The first electrode piece and the third electrode piece are arranged so as to not overlap when projected onto a projection surface parallel to a principal surface of the semiconductor film, and the shortest distance between the first electrode piece and the fourth electrode piece, is greater than the shortest distance between the first electrode piece and the third electrode piece.

Abstract: An LED module according to the present invention includes an LED unit 2 and a case 1, where the LED unit includes an LED chip 21, and the case 1 includes a main body 11 made of a ceramic material and a pad 12a on which the LED unit 2 is mounted. The outer edge 121a of the pad 12a is positioned inward of the outer edge 2a of the LED unit 2 as viewed in plan. These arrangements prevent the light emission amount of the LED module A1 from reducing with time.

Abstract: Provided is a light-emitting device including a semiconductor substrate of a first conductivity type, a semiconductor multilayer reflection mirror of the first conductivity type, formed on the semiconductor substrate, a first semiconductor layer of the first conductivity type, formed on the semiconductor multilayer reflection mirror, a second semiconductor layer of a second conductivity type, formed on the first semiconductor layer, a third semiconductor layer of the first conductivity type, formed on the second semiconductor layer, a fourth semiconductor layer of the second conductivity type, formed on the third semiconductor layer, a first electrode formed on a rear surface of the semiconductor substrate, and a second electrode formed on the fourth semiconductor layer, wherein the semiconductor multilayer reflection mirror includes a first selectively oxidized region and a first conductive region adjacent to the first oxidized region, and the first conductive region electrically connects the semiconductor s

Abstract: A light emitting diode (LED) package is disclosed. The LED package includes a first metal line layer and a second metal line layer bonded to a circuit substrate, a thin film substrate disposed on the first metal line layer and the second metal line layer and configured to include an opening that exposes the first metal line layer and the second metal line layer, and an LED disposed in the opening and brought into contact with the first metal line layer and the second metal line layer.

Abstract: In the semiconductor light emitting device of the present invention, a reflective layer for reflecting light emitted by a semiconductor light emitting element is formed on a Cu wiring pattern, and a bonding section is formed on a light-emitting-element-mounting area on the Cu wiring pattern, to which an electrode of an LED chip is connected, the bonding section being made of a material allowing the semiconductor light emitting element to be soldered on the reflective layer without flux. Consequently, it is possible to realize a high-quality semiconductor light emitting device which has a semiconductor light emitting element firmly attached to a bonding surface and which is capable of emitting light while reducing deterioration in luminosity and color tone shift.

Abstract: According to one embodiment, in a semiconductor light emitting device, a substrate has a first surface and a second surface to face to each other, and side surfaces each having a first region extending approximately vertically from the first surface toward the second surface side and a second region sloping broadly from the first region toward the second surface side. A semiconductor laminated body is provided on the first surface of the substrate and includes a first semiconductor layer of a first conductivity type, an active layer and a second semiconductor layer of a second conductivity type which are laminated in the order. A reflection film is provided on the second surface of the substrate.

Abstract: Provided are a light emitting device package and a lighting device. The light emitting device package includes a base having a via hole passing through a top surface thereof and a bottom surface thereof, a plurality of electrodes formed on the top surface of the base, the plurality of electrodes being electrically connected to a lower portion of the base through the via hole of the base, a frame disposed on the base, the frame having an opening and a light emitting device electrically connected to at least one of the plurality of electrodes in the opening of the frame. A width of the base is wider than a width of the frame, and material having light reflectivity is disposed on the frame.

Abstract: According to one embodiment, a semiconductor light emitting device includes a stacked body, a first electrode, a second electrode, a reflective layer, a first metal pillar, a second metal pillar, and a sealing unit. The stacked body includes first and second semiconductor layers, and a light emitting unit. The light emitting unit is provided between the second portion and the second semiconductor layer. The first electrode is provided on the first semiconductor layer. The second electrode is provided on the second semiconductor layer. The reflective layer covers a side surface of the stacked body and insulative and reflective. The first metal pillar is electrically connected to the first electrode. The second metal pillar is electrically connected to the second electrode. The sealing unit seals the first and second metal pillars to leave end portions of the first and second metal pillars exposed.

Abstract: Disclosed is a light emitting module including a light emitting device package having a circuit board having a cavity, an insulation substrate arranged in the cavity, with a conductive pattern formed thereon, and at least one light emitting device disposed on the insulation substrate, with being electrically connected with the conductive pattern; and a glass cover located on the light emitting device package, with lateral surfaces, a top surface and an open bottom surface, wherein the light emitting device package and the circuit board are electrically connected with each other.

Abstract: A semiconductor light emitting device which can suppress the self-absorption of light propagating in a semiconductor film without hindering current spread therein. A reflecting film provided between a support substrate and the semiconductor film of the device includes reflecting electrodes that are in ohmic contact with the semiconductor film and that form current paths between the reflecting electrodes and surface electrodes in the semiconductor film. The reflecting electrodes are in contact with the semiconductor film at such positions that the surface electrodes, provided on the light-extraction-surface-side surface of the semiconductor film, are not over the reflecting electrodes along a direction of the thickness of the semiconductor film.

Abstract: An LED device with improved LED efficiency is presented. A top surface of a circuit board carrying the LED die is covered with a reflective layer. The reflective surface on top of the circuit board allows the light reflected off a surface of a waveguide to be recycled by being redirected back to the waveguide.