A new approach for the design of dichromatic white light-Emitting Diodes (LEDs) has been proposed by employing InAlGaN irregular multiple quantum well (IMQW) structures. The InAlGaN IMQW structures are assembled by two different type QWs emitting complementary wavelengths. The electronic and optical properties of the designed InAlGaN IMQWs have been analyzed in details by fully considering the effects of strain, well-coupling, valence band-mixing and quasi-bound states using a newly developed theoretical model from the k•p theory. The influence of material components, well width and well number of different type QWs, and barrier thickness on the spontaneous emission spectra of InAlGaN IMQWs was studied. The IMQW structure was obtained which can realize near white light emission by optimizing the structure parameters of IMQW structure for dichromatic white LEDs.

Resonant cavity light-emitting diodes (RCLEDs) which composed of active region surrounded by two distributed Bragg reflector (DBR) mirrors have been reported in the communication system based on Plastic Optical Fiber (POF) and high brightness application. However, high performance of 650nm AlGaInP RCLED, which is strongly depends on the optimization of DBRs, especially the matched reflectivity between p-type and n-type DBR mirrors, is still difficult to obtain. In this paper, the performance of 650nm RCLEDs including 34-pair AlGaAs/AlAs n-type DBRs and different pairs of AlGaInP/AlInP p-type DBRs have been investigated both theoretically and experimentally. Top emitting chips with the size of 225x225μm² without encapsulation were fabricated under the same conditions, experimental results reveal that the device of optimized DBR mirrors with 10-pair p-type DBRs obtain high efficiency, low turn-on voltage and forward resistance, good temperature stability.

A Monte Carlo ray tracing method is applied to analyze the light extraction characteristics of AlGaInP based LED with various shapes of surface texture. Regular, periodic arranged structures were fabricated on p-side-up AlGaInP LEDs through dry etching. The dimension of the structures was optimized by Monte Carlo ray tracing simulation. Compared to the conventional LED, it significantly improved the performance of the chip, the light extraction efficiency was increased more than 11.5%. the enhancement is attributed to the appearance of an additional escape cone for light extraction enabled by surface texture. And it is also easy to extend the Monte Carlo ray tracing method to develop LED lamps, consisting a reflector dish and an epoxy lens.

The process of nanosphere lithography was developed and applied to LED epistructure. We demonstrated p-i-n nanorod LED arrays with some specific characteristics. Moreover, LEDs encompassed with self-aligned nanorods are fabricated. Light diffraction behaviors are characterized. The results are explained by photonic crystal effect.

It is very important to increase light extraction efficiency in LED structure design. The antireflection film technology is a simple and cost-cutting method. In this paper, we proposed a SiON layer as an antireflection coating deposited on the surface of the conventional AlGaInP LED which can be used to improve the performance of the chip. In the conventional AlGaInP LED, ITO thin film was deposited as current spreading layer. The propagation of lights through these layers was analyzed by transfer matrix method. The thicknesses of ITO and SiON layers have been optimized. SiON film was deposited by PECVD. The results of the experiments showed that optical power increased by 11.38% after LED packaged. The difference of peak wavelength between the two samples was less than 1nm.

We proposed and developed a series of high brightness LED street lamps to provide uniform and wide illumination areas on the road, which can eliminate the lamp installation numbers and electrical power consumption effectively. The modularized light engine design makes LED street lamp more flexible in installation and maintenance. It can also enhance the optical and thermal performance of the whole LED street lamp lighting system.

For breaking through the restrictions of multiple LED products with irregular radiation patterns, free-form microlens optics is designed by the Snell's law and "edge-ray principle" for illumination applications. This non-imaging optics can freely redistribute LED radiations onto target surfaces for prescribed uniform illuminations without considering the specific radiation patterns of LED sources. The surface shape of the single free-form microlens is totally determined by the practical illumination requirements, and calculated by using the three dimensional ray tracing method and B-spline fitting way. Some models of free-from microlens optics were done to achieve prescribed rectangular illuminations. The simulation experiments for these models were done, and the results show that the achieved illuminations have high uniformities, precise illuminating shapes, and insensitivity of the radiation pattern of the sources used, which means that free-form microlens optics is applicable in LED lighting with competitive advantages.

We used two types of 1-W white LEDs, both of which had the structure of GaN chip with phosphor covered and packaged in metal PCB boards with laminated aluminum. Of the two types of packaging lens, one is made of hard silica gel, and the other is made of soft plastic. The purpose of this paper is to analyze the aging characters of high-power white LEDs under stresses. In accelerated life tests, the two types of white LEDs were treated with high temperature and DC current distinctively. The tendencies of the decay of luminous flux in the two conditions were basically the same, while the changing trends of the color temperature were different. The hard silica gel had better stability.

We present an ideal host-guest concept for highly efficient phosphorescent OLEDs (PHOLEDs). Highly efficient PHOLEDs with an extremely low doping concentration of 1% are developed. The origin of such a low doping is revealed by energy transfer mechanism studies and ideal host-guest concept. Simple architectures for PHOLEDs are realized based on this ideal host guest concept. Organic bi-layered and triple-layered architectures for PHOLEDs with high efficiency are reported. Results reveal a practical way to fabricate the highly efficient simple structure devices for trouble-free manufacturing processes.

We investigate the dependence of the optical spectral properties of the exciplex in the polymer blend of Poly (9, 9'-dioctylfluorene-co-benzothiadiazole) (ADS133YE) and poly (9,9'-dioctylfluorene-co-bis-N, N'-(4-butylphenyl)-bis-N,N'- phenyl-l,4 - phenylenediamine) (ADS232GE) on the excitation wavelengths and on the composite ratios between these two materials. By controlling the excitation wavelength, the energy transfer can be optimized, which favors the formation of the exciplex on the interface between the two blend phases. Furthermore, changing the composite ratio acutally modifies the mophorlogy of the blend film, modifying the excited states on the interface and giving the microscopic insights into the mechanisms of the exciplex emission. These investigations are important for better understanding the physics of the heterojunction structures in the polymer blends and is thus helpful for the design of organic photovoltaic devices.

In recent years, light emitting diode (LED) display arrays have emerged as the leading technology for large indoor or outdoor display applications. LED has a lot of prominent advantages, for example, the high luminous efficiency, the less power consumption, the longer lifetime for using, the better control performance, and so on. Because the luminance of LED is higher than the traditional light source, the effects of display and picture quality are suitable for the LED display. However, the increment of luminance has a limit for the LED display arrays, which is decided by the vision characteristic of person's eyes. If the luminance goes beyond the limit, the person's eye will feel not comfortable. This paper presents the vision characteristics for the person's eye and the LED features and some methods for solving a certain factors that influence LED picture quality are described.

A novel three-dimensional human body modeling method on laser technology, using the CCD camera to receive the scanning information, based on the theory of aerial photography surveying and 36 characteristic measuring points, is reported here. We introduce the mode integration of human body and the principle of human body feature identifying. The laser scanning human body three-dimensional modeling system is established.

A design is proposed to significantly increase the absorption of a thin layer of absorbing material such as amorphous silicon. This is achieved by patterning a one-dimensional photonic crystal (1DPC) in this layer. Indeed, by coupling the incident light into slow Bloch modes of the 1DPC, we can control the photon lifetime and then, enhance the absorption integrated over the whole solar spectrum. Optimal parameters of the 1DPC maximize the integrated absorption in the wavelength range of interest, up to 45% in both S and P polarization states instead of 33% for the unpatterned, 100 nm thick amorphous silicon layer. Moreover, the absorption is tolerant with respect to fabrication errors, and remains relatively stable if the angle of incidence is changed.

Zr-Al co-doped ZnO (AZZO) were prepared by DC magnetron sputtering on glass slide substrates under different sputtering powers. Microstructure, Electrical and optical properties of AZZO thin films were investigated. The AZZO films with an electrical resistivity as low as 1.07x10^-3Ωcm and an average optical transmission of 88.5% in the visible range were obtained at DC power of 170 W. The optical bandgap depends on the deposition condition, and was in the range of 3.48-3.57 eV. These results make the possibility for light emitting diodes(LEDs) and solar cells with AZZO films as transparent electrodes.

A liquid crystal display (LCD) recently comes into common use. It is possible for this display unit to provide the same size of displaying area as the image screen on the panel. To display a stereoscopic image for left and right eyes, the display screen needs to be divided in half and left and right stereoscopic images must be overlaid for easy 3D viewing. The authors had ever developed a stereo image overlapping method which enables both images to be in same position. A grating film can shift an image into any position by adjusting the interval from the original image plane. However an observer must wear the polarized glasses to separate the overlaid stereoscopic images into appropriate eyes. To improve this problem, we developed a glasses-free 3D stereoscopic display using an LCD display panel, a view control film and a grating film for stereoscopic viewing. The observer can watch overlapped stereoscopic images for left and right eyes without special glasses such as polarized glasses.

A study of virtual-reality system has been popular and its technology has been applied to medical engineering, educational engineering, a CAD/CAM system and so on. The 3D imaging display system has two types in the presentation method; one is a 3-D display system using a special glasses and the other is the monitor system requiring no special glasses. A liquid crystal display (LCD) recently comes into common use. It is possible for this display unit to provide the same size of displaying area as the image screen on the panel. A display system requiring no special glasses is useful for a 3D TV monitor, but this system has demerit such that the size of a monitor restricts the visual field for displaying images. Thus the conventional display can show only one screen, but it is impossible to enlarge the size of a screen, for example twice. To enlarge the display area, the authors have developed an enlarging method of display area using a mirror. Our extension method enables the observers to show the virtual image plane and to enlarge a screen area twice. In the developed display unit, we made use of an image separating technique using polarized glasses, a parallax barrier or a lenticular lens screen for 3D imaging. The mirror can generate the virtual image plane and it enlarges a screen area twice. Meanwhile the 3D display system using special glasses can also display virtual images over a wide area. In this paper, we present a monocular 3D vision system with accommodation mechanism, which is useful function for perceiving depth.

A yellow-orange-emitting Ba²⁺ codoped Sr₃SiO₅: Ce³⁺, Li⁺ phosphor was prepared by high-temperature solid-state reaction. Through transitions of 5d→4f in Ce³⁺, the phosphor showed a very broad and strong yellow emission under near ultraviolet (UV) or blue light excitation. The shifts of the emission band to longer wavelength (yellow-orange) of the Sr₃SiO₅: Ce³⁺, Li⁺ yellow phosphor under the 450-470 nm excitation range have been achieved by adding the element Ba²⁺ in the Sr₃SiO₅ host. White light could be obtained by combining this phosphor with 460nm light-emitting diodes. As the concentrations of the Ba²⁺, Ce³⁺ and Li⁺ ions in the phosphor were 0.35mol, 0.024mol and 0.024mol respectively, the InGaN-based Ba2+ codoped Sr₃SiO₅: Ce³⁺, Li⁺ LED presented intense white emitting and good color rendering of 88.

A trichromatic phosphor-free white light-emitting diode (LED) has been implemented by using adhesive bonding scheme. The device has been operated as a three-terminal device with independent electrical control of an AlGaInPbased red LED chip and a GaN-based dual-wavelength (blue and green) LED chip. As 25mA and 60mA was injected into the red and blue-green LED chips at room temperature respectively, white light emission could be observed with CIE chromaticity coordinates (0.3330,0.3241), correlated color temperature Tc=5467K and optical power Φe=2.223mW. The electroluminescence measurements also show that the emitted white light is composed of blue, green and red lights, centered at around 452nm, 517nm and 632nm. The fabrication and the electrical and optical performances of such white LED were described.

This paper presents a new Three-Dimensional display method, so called Directional Light Scanning 3D display. By using holographic screen as a beam scanner and high frame rate Spatial Light Modulator (SLM), this method requires only one SLM but can display high resolution 3D images, solving the usual problem of lack of resolution.