Reflector Design Method for Rotational Uniform Illuminance System with LED

Based on nonimaging design method, uniform illuminance systems with LED source were developed to create a uniform illuminated circular region with a desired size in a screen at a prescribed place. By using ray-tracing software based on Monte-Carlo method, the simulation results show that in the illuminated region the luminous uniformity is higher than 90%.

Study on Relationship between InGaAsP/InP LPE Wafer Morphology,Interface Property and Device Characteristics

Five kinds of InGaAsP/InP heterostructure materials grown with LPE have been measured by means of Auger electron analysis, X-ray double-crystal diffraction, selective etching and surface morphology analysis. The relation between crystal mismatch and interface property of such materials has been studied and the results could be understood in terms of the growth kinetics at the heterojunction interface. The comparison of the characteristics of the electronic and optoelectronic devices fabricated with the wafers under different interface properties has been carried out. And it also has been demonstrated that the wafer surface morphology changes with the compositional gradation in a certain relationship.

Growth and properties of wide spectral white light emitting diodes

Wide spectral white light emitting diodes have been designed and grown on a sapphire substrate by using a metal-organic chemical vapor deposition system. Three quantum wells with blue-light-emitting, green-light-emitting and red-light-emitting structures were grown according to the design. The surface morphology of the film was observed by using atomic force microscopy. The films were characterized by their photoluminescence measurements. X-ray diffraction t9/2/9 scan spectroscopy was carried out on the multi-quantum wells. The secondary fringes of the symmetric ω/2θ X-ray diffraction scan peaks indicate that the thicknesses and the alloy compositions of the individual quantum wells are repeatable throughout the active region. The room temperature photoluminescence spectra of the structures indicate that the white light emission of the multi-quantum wells is obtained. The light spectrum covers 400 700 nm, which is almost the whole visible light spectrum.

Simulation of Fast-Recovery Cross-Modulation Characteristics in Semiconductor Optical Amplifier with Assist Light

We analyzed the characteristics of cross-modulations (XM) and their recovery times in a semiconductor optical amplifier by a newly-developed TMM. The calculated results suggest faster recovery of the XMs by introducing a high-power assist light.

Slow and fast light in quantum-well and quantum-dot semiconductor optical amplifiers Invited Paper

Slow and fast light in quantum-well （QW） and quantum-dot （QD） semiconductor optical amplifiers （SOAs） using nonlinear quantum optical effects are presented. We demonstrate electrical and optical controls of fast light using the coherent population oscillation （CPO） and four wave mixing （FWM） in the gain regime of QW SOAs. We then consider the dependence on the wavelength and modal gain of the pump in QW SOAs. To enhance the tunable photonic delay of a single QW SOA, we explore a serial cascade of multiple amplifiers. A model for the number of QW SOAs in series with variable optical attenuation is developed and matched to the experimental data. We demonstrate the scaling law and the bandwidth control by using the serial cascade of multiple QW SOAs. Experimentally, we achieve a phase change of 160^o and a scaling factor of four at 1 GHz using the cascade of four QW SOAs. Finally, we investigate CPO and FWM slow and fast light of QD SOAs. The experiment shows that the bandwidth of the time delay as a function of the modulation frequency changes in the absorption and gain regimes due to the carrier-lifetime variation. The tunable phase shift in QD SOA is compared between the ground- and first excited-state transitions with different modal gains.

Discretely-supported nanoimprint lithography for patterning the high-spatial-frequency stepped surface

Non-planar morphology is a common feature of devices applied in various physical fields,such as light or fluid,which pose a great challenge for surface nano-patterning to improve their performance.The present study proposes a discretely-supported nanoimprint.lithography(NIL)technique to fabricate nanostructures on the extremely non-planar surface,namely high-spatial-frequency stepped surface.The designed discretely imprinting template implanted a discretely-supported intermediate buffer layer made of sparse pillars arrays.This allowed the simultaneous generation of air-cushion-like buffer and reliable support to the thin structured layer in the template.The resulting low bending stiffness and distributed concentrated load of the template jointly overcome the contact difficulty with a stepped surface,and enable the template to encase the stepped protrusion as tight as possible.Based on the proposed discretely-supported NIL,nanostructures were fabricated on the luminous interface of light emitting diodes chips that covered with micrometer step electrodes pad.About 96%of the utilized indium tin oxide transparent current spreading layer surface on top of the light emitting diode(LED)chips was coated with nanoholes array,with an increase by more than 40%in the optical output power.The excellent ability of nanopatterning a non-planar substrate could potentially lead innovate design and development of high performance device based on discretely-supported NIL.