198results about How to "Improve electro-optical conversion efficiency" patented technology

The present invention relates to radiation, preferably light emitting, devices with a high radiation emission efficiency and to fabricating these as small devices in an array of such devices. In one embodiment, the emitting devices can be placed in dense arrays. In another embodiment, outcoupling efficiency of the devices is improved, which leads to a reduced power consumption for a given radiation output power. In another embodiment, the speed of the radiation is increased, hence the serial bandwidth per optical channel is increased. The invention further relates to light emitting devices that exhibit uniform radiation emission characteristics. The light emitting devices (diodes, LEDs) of the present invention can be used for applications wherein two-dimensional LED arrays, particularly low-power arrays, are useful, such as in display technology. Active matrix displays relying on liquid crystals (e.g. integrated on CMOS circuitry) could be replaced by LED arrays. Dense and bright one-dimensional LED arrays are useful for example for printing and copying. Also for single LED applications it is important to have a maximum of photons escaping from the light emitting surface. The intensity of light per unit area (the brightness) is larger, and this is useful in many applications. Furthermore, the packaging cost can be reduced. In order to achieve a large global efficiency, many conventional LEDs need an elaborate package that includes a cavity with mirrors, because the light is emitted from more than one surface of the LED.

The invention discloses a silicone lens for LED (Light Emitting Diode) packaging, which is used for being adhered to the surface of a COB (Chip On Board) packaging body so as to improve the light extraction efficiency. The silicone lens is in a convex surface structure, and comprises at least two silicone layers arranged in sequence from inside to outside, wherein the refractive index of the silicone layer positioned on the outer layer is smaller than or equal to that of the silicone layer positioned on the inner layer. The multi-layer silicone lens disclosed by the invention can greatly improve the light extraction efficiency of an LED light source, particularly a high and medium power COB packaging body.

The invention relates to a Bragg refractive waveguide edge transmitting semiconductor laser with a low horizontal divergence angle, wherein the P electrode of the laser is placed on the top face of a cover layer and is electrically connected onto the cover layer; the N electrode is positioned on the back face of a substrate and is electrically connected to the substrate; a center cavity is positioned between an upper waveguide layer and a lower waveguide layer; an active area is inserted in the center cavity; a Bragg refractive waveguide formed by periodically distributing a plurality of layers of N-doped materials with a high refractive index and a low refractive index is adopted in the lower waveguide layer on; and a Bragg refractive waveguide formed by periodically distributing a plurality of layers of P-doped materials with a high refractive index and a low refractive index is adopted in the upper waveguide layer. The Bragg refractive waveguide edge transmitting semiconductor laser with the low horizontal divergence angle has the advantages that: effects such as catastrophic damage, hole burning, electric heat overburning, beam filamentization and the like on the end face of the traditional edge transmitting semiconductor laser can be effectively improved, and the laser can realize the large mode-volume and stable single-transverse-mode work because of the great gain loss difference between a basic mode and a high-order mode, the full wave at half maximum (FWHM) of the transverse far-field divergence angle of the laser can reach below 10 DEG.

A method of forming a highly doped layer of AlGaN, is practiced by first removing contaminants from a MBE machine. Wafers are then outgassed in the machine at very low pressures. A nitride is then formed on the wafer and an AlN layer is grown. The highly doped GaAlN layer is then formed having electron densities beyond 1×1020 cm−3 at Al mole fractions up to 65% are obtained. These levels of doping application of n-type bulk, and n / p tunnel injection to short wavelength UV emitters. Some applications include light emitting diodes having wavelengths between approximately 254 and 290 nm for use in fluorescent light bulbs, hazardous materials detection, water purification and other decontamination environments. Lasers formed using the highly doped layers are useful in high-density storage applications or telecommunications applications. In yet a further embodiment, a transistor is formed utilizing the highly doped layer as a channel.

The invention provides an LED (Light Emitting Diode) chip provided with a stepped current blocking structure and a fabricating method thereof. The fabricating method comprises the steps of: providing at least one LED epitaxial wafer comprising a substrate and a light emitting epitaxial structure on the LED epitaxial wafer; fabricating the stepped current blocking structure on the surface of the LED epitaxial wafer vertical to a region of a first electrode correspondingly prefabricated; and fabricating transparent conductive layers on the surfaces of the LED epitaxial wafer and the stepped current blocking structure, and then fabricating a first electrode, a second electrode and a protective layer correspondingly. According to the LED chip provided with a stepped current blocking structure and the fabricating method of the LED chip provided with the stepped current blocking structure provided by the invention, the gradient at the edge of the stepped current blocking structure is slowed so that the contact area of the transparent conductive layer and the stepped current blocking structure is increased, the situation that the transparent conductive layer (ITO) on the side wall (at the step) at the edge of the current blocking structure becomes thinner and even breaks can be avoided, the step covering capacity of the transparent conductive layer is improved, the current spreading capacity of the transparent conductive layer is further improved, the electro-optical conversion efficiency of the LED chip is increased, and the brightness of the LED chip is enhanced.

The invention relates to a high-brightness white-light source with an optical waveguide. The high-brightness white-light source is characterized by comprising an excitation light source and an optical waveguide corresponding to the excitation light source, wherein the optical waveguide is provided with an incident port and an emitting port; a white-light excitation body internally provided with fluorescent powder is connected to the emitting port of the optical waveguide; the light emitted by the excitation light source is transmitted through the optical waveguide to excite the fluorescent powder in the white-light excitation body so as to be combined to form the white light. The high-brightness white-light source with the optical waveguide is high in optic-electro conversion efficiency and luminous flux; the fluorescent powder is far from the excitation light source and can be in a deferred degradation without being cooled; the high-brightness white-light source is a compact structure, and is very suitable for the place required for introducing the white light through the optical waveguide.

The invention discloses an intermediate infrared antimonide laser device structure adopting DWELL, namely the intermediate infrared laser structure of DWELL, wherein, a DOT is embedded in a WELL, and the efficiency of the device is improved by increasing the number of the validity period of DWELL in the device. In component of active area is reduced, and quantum dots, well width and covering layers are optimized to reduce epitaxial layer strain to the minimum. As the emission efficiency and optical gain of the quantum dots are stronger than quantum wells; the capture ability, reflectivity and optical limiting ability of DWELL to electrons are stronger than single-layered quantum dots and multi-quantum dot structure, and the DWELL structure has higher emission efficiency. The intermediate infrared laser of the DWELL structure has both characteristics of the traditional quantum well and a quantum dot laser, and the carrier in DWELL has higher composite efficiency, thus the laser structure can work under higher temperature.

A method of adjusting a power density in a laser device including a VCSEL array providing an increased power density at a high wall-plug efficiency in that the lateral design parameters are appropriately selected on the basis of a relationship that has been established for a specified vertical design, a corresponding process technology and specified operating conditions. Thus, the total output power, the power density, and the efficiency may be optimized independently from other design criteria and application requirements by tuning only the lateral size of the individual VCSEL elements and the pitch of nearest neighbors of the elements within the array. Hence, for a lateral size of less than 30 μm and a pitch of less than 80 μm, a highly efficient VCSEL array can be provided with a high power density, thereby optimizing manufacturing costs for the output power per chip area.

The invention discloses a photocatalytic air purifier which takes a light-emitting diode as light source, a dust-resistant filter net which is detachable and easy to clean is arranged at an air inlet which is arranged on the lower part of a shell body of a purifier, the dust-resistant filter net which is detachable and easy to clean is arranged at an air outlet which is arranged on the upper part of the shell body; a light-emitting diode array which is taken as the light source and a photocatalytic layer are parallelly arranged in the shell body, the photocatalytic layer is composed of a modified titanium dioxide photocatalyst which is loaded on an activated carbon fiber; the photocatalytic layer of the air purifier simultaneously has the effects of absorption enrichment and photocatalytic degradation of volatile organic compounds, thereby effectively improving the efficiency of the photocatalytic degradation; the light-emitting diode array is adopted as the light source, thereby overcoming the defect of uneven illumination of an ultraviolet lamp tube and being characterized by high optical to electrical conversion rate, long service life and high space and time efficiency, the high-low arrangement of the light-emitting diode array and the photocatalytic layer utilizes the characteristic that gas is raised after heating to realize the effective convection of air without a fan, thereby reducing the energy consumption and simplifying the device.

The related fast-forming laser diode energy source comprises: a source LD, a column mirror group included a fast-axis and slow-axis collimation column mirror with bus-bar vertically, a beam expander to expand the slow-axis parallel beam to let beam diameter at two directions as same cycle, and a frame or shell. Besides, it also contains a direction indicator, a beam-joining device, a coupled expander, a dynamic focus module, and an x-axis / y-axis scanning mirror. This invention has small size and well reliability.

The invention discloses a rotating mirror scanning dual waveband semiconductor laser sterilization system for a medical device, which comprises an infrared semiconductor laser, an ultraviolet semiconductor laser, optical fiber collimators, a zooming coupled lens assembly, an infrared beam scanning rotating mirror and an ultraviolet beam scanning rotating mirror. The system can be applied in various modes and occasions and can make important contribution to reduce a fatality rate and a disability rate and restore health as soon as possible in the field of medical treatment and intensive care infection prevention and treatment; the system achieves quick and thorough sterilization and has high efficiency by adopting an intense laser sterilization mode and integrating the advantages of a strong heating effect of an infrared laser and a strong protein molecular ionization damage effect of an ultraviolet laser; and the system is portable and reusable, is not contacted with a human body, has no obvious direct or indirect influence on the human body and is convenient to realize.

The invention relates to a laser processing method and in particular to a double-beam laser synchronous welding method for a titanium alloy wallboard and a rib strip through a T-shaped joint. The titanium alloy wallboard is fixed on a movable worktable through a positioning and supporting seat, wherein the rib strip is perpendicularly arranged on the titanium alloy wallboard and is tightly pressed through a tooling fixture; the T-shaped joint is formed by the rib strip and the titanium alloy wallboard; two sides of the T-shaped joint are synchronous welded through a first laser welding device and a second laser welding device. By virtue of the method, the two sides of the T-shaped joint can be synchronously welded by using two beams of laser; the welding efficiency is improved; the purpose of molding at a time can be achieved.

The invention relates to an intracavity-frequency-doubling 532nm single-longitudinal-mode laser based on seed light injection. A resonance detection method is used for obtaining 1064nm single-frequency pulse laser for seed injection is obtained and 532nm single-longitudinal-mode pulse laser is obtained through intracavity frequency doubling. A laser resonant cavity is a U-shaped cavity. Two high-peak-power laser diodes (LD) are used for pumping laser crystals from an end surface, a high-precision thermoelectric cooler is used for controlling the temperature of the laser crystals and green light output is obtained through intracavity lithium triborate (LBO) frequency doubling. The intracavity-frequency-doubling 532nm single-longitudinal-mode laser based on seed light injection has the characteristics of high efficiency, high energy, conduction cooling, narrow line width, high frequency stability, compact structure and high working stability.

The invention discloses a thin-film AlGaInP light-emitting diode chip and its preparation method. The light-emitting diode chip comprises a bonding substrate with positive and negative faces. From thefront surface of the bonding substrate upwards, it is sequentially provided with: a substrate side metal bonding layer, an epitaxial side metal bonding layer, a P surface diffusion barrier metal layer and a P surface reflection ohm contact layer; from the P surface reflection ohm contact layer to the top, it is sequentially provided with P-type current spreading layer, the P-type limiting layer,the P-side spatial layer, the multi-quantum well light-emitting region, the N-side spatial layer, the N-type limitation layer, the N-type coarse layer, the N-type ohm contact layer and the N electrode; and the reverse side of the bonding substrate is a P electrode. The P-plane reflecting ohm contact layer adopted by the invention has the functions of light reflection and ohm contact; by optimizingthe spacing distance of the block and the width of the N electrode through the blocking of the P-plane reflection ohm contact layer, the current injection concentration problem of the N-electrode corresponding region can be suppressed, and the N electrode shielding effect can be effectively reduced. The invention has the advantages of effectively improving the photoelectric conversion efficiency,simple structure and the like.

The invention relates to an asymmetrical 980nm semiconductor laser structure with high power and wide waveguide, comprising a substrate, a buffer layer, an N-type lower limiting layer, a lower upper waveguide layer, a lower barrier layer, a quantum well layer, an upper barrier layer, an upper waveguide layer, a P-type upper limiting layer, a transitional layer and an electrode contact layer. The substrate is an N-type gallium arsenide material of a surface (100) and is used for the epitaxial growth of each layer material of a laser thereon; the buffer layer is made of an N-type gallium arsenide material and manufactured on the substrate; the N-type lower limiting layer is made of an N-type gallium aluminum arsenide material and manufactured on the buffer layer; the lower waveguide layer is made of an N-type gallium aluminum arsenide material and manufactured on the lower limiting layer; the lower barrier layer is made of gallium phosphorus arsenide material and manufactured on the lower waveguide layer; the quantum well layer is manufactured on the lower barrier layer; the upper barrier layer is manufactured on the quantum well layer; the upper waveguide layer is manufactured on the upper barrier layer; the P-type upper limiting layer is made of a P-type gallium aluminum arsenide material and manufactured on the upper waveguide layer; the transitional layer is made of a gallium arsenide material and manufactured on the P-type upper limiting layer; and the electrode contact layer is made of a gallium arsenide material and manufactured on the transitional layer.

The invention discloses a quantum well epitaxy structure of a semiconductor laser, in particular to a quantum well epitaxy structure of a high-efficiency semiconductor laser in a 940 nm-1000 nm wave band. The quantum well epitaxy structure comprises a substrate, a buffer layer, a lower limiting layer, a lower waveguide layer, a quantum well layer, an upper waveguide layer, an upper limiting layer and an electrode contact layer, wherein the buffer layer, the lower limiting layer, the lower waveguide layer, the quantum well layer, the upper waveguide layer, the upper limiting layer and the electrode contact layer are sequentially deposited on the substrate; the upper waveguide layer and the lower waveguide layer are AlxGaAs, and x is equal to 0.13-0.2; and the upper limiting layer and the lower limiting layer are AlyGaAs, and y is equal to 0.3-0.39. The quantum well epitaxy structure solves the problems of high working voltage and low photoelectric conversion efficiency of the semiconductor laser by optimizing the Al content of the waveguide layers and the limiting layers of the quantum well epitaxy structure, and achieves the purposes of reducing the working voltage and enhancing the photoelectric conversion efficiency.

The invention belongs to the technical field of semiconductor optic electronics and particularly discloses a stain-balance active-area gradient potential well layer semiconductor laser structure. The structure comprises a buffer layer, a lower matching layer, a lower limiting layer, a lower transition layer, a lower waveguide layer, a multiple-quantum well layer, an upper waveguide layer, an upper transition layer, an upper limiting layer, an upper matching layer and an electrode contact layer which are in sequential epitaxial growth from top to bottom by adopting a metal-organic chemical vapor deposition method. Improvements are performed on lowering threshold current of a laser, increasing output power, improving photoelectric conversion efficiency, prolonging service life, improving reliability and the like to obtain the semiconductor laser with the novel structural material system on the basis of improving quality of a material mutation heterogeneous interface of the multiple-quantum well layer, lowering mismatching ratio of strain of lattice constant, reducing mismatching ratio of total accumulated strain of an active area of a quantum well and avoiding lattice relaxation occurring to the quantum well heterogeneous interface.

In order to solve the problems of high optical field loss on P-type DBR (distributed Bragg reflector) side and restricted conversion efficiency of the existing vertical cavity surface emitting semiconductor laser, the invention relates to a high-efficiency vertical cavity surface emitting semiconductor laser with asymmetric optical field distribution, which belongs to the technical field of semiconductor laser. The high-efficiency vertical cavity surface emitting semiconductor laser with asymmetric optical field distribution comprises, from bottom to top, an N-side electrode, an N-type substrate, an N-type buffer layer, an N-type segmented DBR, an active region, an oxidation confinement layer, a P-type segmented DBR, a P-type cover layer and a P-side electrode, wherein the refractive index difference of the former 6 to 8 pairs of high- and low-refractive index material of the N-type segmented DBR close to the active region is smaller than that of the latter low-refractive index material pairs; and the refractive index difference of the former 6 to 8 pairs of high- and low-refractive index material of the P-type segmented DBR close to the active region is larger than that of the latter low-refractive index material pairs. The high-efficiency vertical cavity surface emitting semiconductor laser provided by the invention has high photoelectrical conversion efficiency, and wide application prospect.

A method of adjusting a power density in a laser device including a VCSEL array providing an increased power density at a high wall-plug efficiency in that the lateral design parameters are appropriately selected on the basis of a relationship that has been established for a specified vertical design, a corresponding process technology and specified operating conditions. Thus, the total output power, the power density, and the efficiency may be optimized independently from other design criteria and application requirements by tuning only the lateral size of the individual VCSEL elements and the pitch of nearest neighbors of the elements within the array. Hence, for a lateral size of less than 30 μm and a pitch of less than 80 μm, a highly efficient VCSEL array can be provided with a high power density, thereby optimizing manufacturing costs for the output power per chip area.

The invention discloses a surface plasma light-catalyzed reaction device based on photonic crystal fiber. A fiber core of the photonic crystal fiber is provided with a plurality of air vent holes; part of the air vent holes are filled with surface plasma photocatalyst through the method of selectively filling in the air vent holes of the photonic crystal fiber; and the surface plasma light-catalyzed reaction device based on the photonic crystal fiber comprises a solid laser, a nonselective absorbent, a vacuum air chamber and a light-catalyzed reaction product collecting device which are connected sequentially. Compared with the prior art, the surface plasma light-catalyzed reaction device adopts photonic crystal fiber as a light-transmitting medium and a carrier of a catalyst as well as a transport corridor of reactants, combines the advantages of high energy density, high beam quality, high electro-optic conversion efficiency and easiness in fiber coupling of laser, and can improve the contact area and the reaction time of gaseous reactants and the catalyst as well as the utilization ratio of laser energy.

The invention discloses a color temperature adjustable display system comprising a color temperature setting device, an application processor, a display module group and a backlight module group. The input end of the application processor is connected with the color temperature setting device. The output end of the application processor is connected with display module group and the backlight module group. The application processor comprises a pulse width controller and a graphic data transmitter. The backlight module group comprises a backlight driver and backlight lamp groups which are connected. The backlight lamp groups comprise at least one cool color lamp group and at least one warm color lamp group. The color temperature setting device converts color temperature settings of a user into color temperature parameter signals to be transmitted to the pulse width controller. The pulse width controller converts the color temperature parameter signals into pulse width modulation signals and controls the brightness of the cool color lamp groups and the brightness of the warm color lamp groups through the backlight driver. The color temperature adjustable display system is high in electro-optical conversion efficiency, low in energy consumption and suitable for a liquid crystal panel of red, green, blue and white pixel arrangement.

A traditional vertical cavity surface emission semiconductor laser is in a completely symmetric round shape, output light of the laser is round symmetric light beams, the light beams are not hollow and is in an instable polarization state. The invention provides a semiconductor laser with an elliptic annular window. The structure is shown as figures: the elliptic annular window 1, an upper electrode 2, an ohmic contact layer 3, an upper distributed Bragg reflection mirror 4, an oxide limitation layer 5, a semiconductor material active gain layer 6, a lower distributed Bragg reflection mirror 7, a substrate 8 and a lower electrode 9, the overall structure from the elliptic annular window to the active gain layer is an elliptic cylindrical structure, the ratio selection range between the length of a long shaft and the length of a short shaft of the elliptic structure is 3:2 to 5:4, a central region of the elliptic cylindrical structure is hollow, and an elliptic etching region 10 formed by etching is etched from the ohmic contact layer to the upper distributed Bragg reflection mirror. The semiconductor laser works in an electric pumping mode, elliptic hollow light beams can be emitted under the effect of the elliptic annular window, the emitted elliptic hollow light beams have favorable polarization characteristics, and the polarization is in a stable state.

The invention discloses a high-power semiconductor laser light source system for laser processing. The high-power semiconductor laser light source system for laser processing comprises a plurality of semiconductor laser stack arrays and shaping lens groups, wherein the semiconductor laser stack arrays are arranged in a sector shape or a cone shape or a spherical shape as a whole; the shaping lens groups are individually arranged in a manner of respectively corresponding to each semiconductor laser stack array; and optical axes formed by various semiconductor laser stack arrays and corresponding shaping lens groups are converged at the outlet of the high-power semiconductor laser light source system. The high-power semiconductor laser light source system for laser processing, disclosed by the invention, has the advantages of simple principle, small volume, high electro-optic conversion efficiency, high power, high brightness, adjustable power, capability of realizing myriawatt-level output and capability of being directly applied to the field of laser processing.

The invention relates to a photoelectric marking technology, in particular to an active photoelectric marking method for an MEMS (Micro-electromechanical Systems) infrared light supply array. The invention solves the problem that the conventional photoelectric marking technology is greatly impacted by external environment, cannot meet the requirements of all-weather work, cannot be used for invisible marking under an asymmetrical condition, is low in identifying efficiency, and is small in the range of a reflected light viewing field. The active photoelectric marking method for the MEMS infrared light supply array is achieved by adopting the following steps: a, an infrared light supply array module is manufactured; b, the radiation signals of an FPGA (Field Programmable Gata Array), used for controlling the infrared light supply array module, are simple point infrared spot signals; and c, the radiation signals of the FPGA, used for controlling the infrared light supply array module, are cyclic switching raster graphic signals. The active photoelectric marking method for the MEMS infrared light supply array, provided by the invention, is applicable to the fields of airplane falling guidance, pilotage, routing indication, bridge marking, personnel search and rescue, subaerial space wireless communication, identification and tracking of military targets, and the like.

The invention relates to the field of obstacle clearing instruments, in particular to an intelligent laser obstacle clearing instrument which comprises a laser mainframe box; a power adjusting deviceis mounted on the side wall of the front end of the laser mainframe box, and the intelligent laser obstacle clearing instrument has the advantages that the intelligent laser obstacle clearing instrument adopts an optical fiber laser, the electro-optical conversion efficiency is high, and the power consumption of the whole machine is low; laser output can be dynamically focused, laser power is utilized to the maximum extent, and obstacle removing operation is accurately conducted; an electric intelligent cradle head adopts a precise turbine worm speed reducer, so that the transmission structureis compact and precise; a GPRS remote control device is arranged, authorization permission and authority management can be carried out on the equipment through a mobile phone APP, and the position ofthe equipment can be monitored in real time, so that risk management and control can be effectively carried out on the equipment, and the use safety of the equipment is improved; a remote control keyboard integrating target display, direction control and laser control is adopted for aiming, cradle head direction adjustment, laser power adjustment and light emitting control.

The invention provides a solid laser, which comprises a semi-conductor laser planer array which is used to output pump light and is formed by a plurality of semi-conductor lasers, an optical coupled device which is used to couple the pump light, a resonant chamber which can output laser in parallel which is input in parallel and a laser crystal which is arranged in the resonant chamber. The invention proposes an innovative idea of simultaneously applying a plurality clusters of parallel solid laser, which effectively achieves the output of semi-conductor pump solid laser in high efficiency and big power in some extent in the parallel output mode of a plurality clusters of solid laser. The solid laser can achieve high-efficiency output through utilizing the combination of multipath lower-power laser, compared with a single semi-conductor pump solid laser, the solid laser can excellently achieve thermal dispersion since the beam-splitting output of pump light under the premise of the same output power, can reduce heat load of crystal, effectively solve the problem of thermal effect of laser crystal, and improve electro-optical conversion efficiency and the flexibility of the resonant chamber design.

The invention provides an OLED light-emitting device and a preparation method thereof. The OLED light-emitting device comprises a first electrode; an organic function layer formed on the first electrode; a second electrode formed on the organic function layer; an optical distance adjustment layer formed on the second electrode and used for adjusting the optical length of the OLED light-emitting device; and a semi-reflective semi-permeable layer formed on the optical distance adjustment layer and used for adjusting phase difference of the light emitted out from the optical distance adjustment layer when the light is reflecting. According to the OLED light-emitting device and the preparation method thereof, the adjustment difficulty of the device can be reduced, the production qualified rate is improved, and the cost is reduced. Besides, the thickness of the electro-optical conversion part of the device is far smaller than that of the structure in the prior art, so that drive voltage of the whole device gets smaller, electro-optical conversion efficiency of the device is improved at the meanwhile power consumption is reduced, and the service life of the device is increased. Besides, through the OLED light-emitting device, colour difference is also improved.

The invention discloses a laser emitter which comprises a driving circuit, an AlN substrate and a laser tube core. Components of the driving circuit are integrated on the AlN substrate; the laser tubecore is attached to the AlN substrate; and the driving circuit is electrically connected with the laser tube core. According to the laser emitter, components of the driving circuit and a laser arrayare integrated, the parasitic impedance of the driving circuit and a laser path is reduced, fewer technical steps are included, heave-current narrow-pulse laser emission under a temperature control condition can be provided, and an optical collimation function is provided.