31.38 Gb/s GaN-based LED array visible light communication system enhanced with V-pit and sidewall quantum well structure

Although the 5G wireless network has made significant advances,it is not enough to accommodate the rapidly rising requirement for broader bandwidth in post-5G and 6G eras.As a result,emerging technologies in higher frequencies including visible light communication(VLC),are becoming a hot topic.In particular,LED-based VLC is foreseen as a key enabler for achieving data rates at the Tb/s level in indoor scenarios using multi-color LED arrays with wavelength division multiplexing(WDM)technology.This paper proposes an optimized multi-color LED array chip for high-speed VLC systems.Its long-wavelength GaN-based LED units are remarkably enhanced by V-pit structure in their efficiency,especially in the“yellow gap”region,and it achieves significant improvement in data rate compared with earlier research.This work investigates the V-pit structure and tries to provide insight by introducing a new equivalent circuit model,which provides an explanation of the simulation and experiment results.In the final test using a laboratory communication system,the data rates of eight channels from short to long wavelength are 3.91 Gb/s,3.77 Gb/s,3.67 Gb/s,4.40 Gb/s,3.78 Gb/s,3.18 Gb/s,4.31 Gb/s,and 4.35 Gb/s(31.38 Gb/s in total),with advanced digital signal processing(DSP)techniques including digital equalization technique and bit-power loading discrete multitone(DMT)modulation format.

Development of a Wireless-Controlled LED Array for the Tunable Optogenetic Control of Cellular Activities

1.Introduction In order to decipher a complex biological process,tools are required to perturb the various players involved to gain information about the important parameters.Optogenetic modules are genetically encoded molecular reagents that,when expressed in cells,allow a specific biological process to be precisely controlled by light in a spatiotemporal manner[1].Optogenetics thus offers cell biologists an unprecedented new way to perturb cellular activities.The application of optogenetic approaches in cellular biology and synthetic biology research has evolved tremendously in the last few years[2–4].

High-resolution portable lens-free on-chip microscopy with RGB LED via pinhole array

Lens-free on-chip microscopy with RGB LEDs(LFOCM-RGB)provides a portable,cost-effective,and high-throughput imaging tool for resource-limited environments.However,the weak coherence of LEDs limits the high-resolution imaging,and the luminous surfaces of the LED chips on the RGB LED do not overlap,making the coherence-enhanced executions tend to undermine the portable and cost-effective implementation.Here,we propose a specially designed pinhole array to enhance coherence in a portable and cost-effective implementation.It modulates the three-color beams from the RGB LED separately so that the three-color beams effectively overlap on the sample plane while reducing the effective light-emitting area for better spatial coherence.The separate modulation of the spatial coherence allows the temporal coherence to be modulated separately by single spectral filters rather than by expensive triple spectral filters.Based on the pinhole array,the LFOCM-RGB simply and effectively realizes the high-resolution imaging in a portable and cost-effective implementation,offering much flexibility for various applications in resource-limited environments.

Design of LED display based on FPGA

If single chip micro computer controls light-emitting diode(LED),it needs abundant peripheral resources,but in this way,it is not convenient to be expanded,modified and maintained.In order to overcome these shortcomings,field programmable gate array(FPGA)is used to control LED.The hardware design uses low power consumption and high performance device EP1C6Q240C8.Quartus II is the software development environment.There are three modules built under the software development environment:divided clock module,word stock module and LED dot matrix display module,and these independent modules are connected to be a whole system.Finally,32×64 dot matrix display is realized successfully.It is convenient for the customer to adjust the three independent modules according to actual demands and it is easier to realize online updation.

Lamp Distribution Design for Adjustment of Florescence in Floral Production

[Objective] The aim was to introduce characters of light sources and select the optimal lamp scheme for floral production in greenhouses. [Method] With chrysanthemum cuttings as materials, HPSL, energy-saving fluorescent lamp, and LED agricultural lamp were made use of to carry out field tests in order to compare practical effects according to light characters of different lamps and plant growth de-mands. [Result] The results show that LED lamp performed the best of the three in practical use. LED square lamp designed in bat-wing shape would be the most ben-eficial for lamp distribution in a greenhouse. [Conclusion] LED agricultural lamp is the most popular currently, for it is energy saving and easy for operation.

Analysis and simulation of high-power LED array with microchannel heat sink

The high power light emitting diode （LED） array integrated with the microchannel heat sink is designed in this paper, and then optimal analysis and simulation have been carried out. According to the theory of heat transfer and fluid mechanics, the calculation of the thermal resistance for the microchannel heat sink is obtained, and the thermal resis- tance is minimized. Finally the simulation with FLUENT software is developed to verify the theoretical analysis. Established analysis and simulation show that the width of the cooling channel is 0.1 mm, and the cooling water flow rate is 1 m/s. On the other hand, the system acquires the best heat dissipation effect, and the minimum of thermal resis- tance is 0.019 W/℃.

Lau Effect Using LED Array for Lithography

Illumination with LEDs is of increasing interest in imaging and lithography.In particular,compared to lasers,LEDs are temporally and spatially incoherent,so that speckle effects can be avoided by the application of LEDs.Besides,LED arrays are qualified due to their high optical output power.However,LED arrays have not been widely used for investigating optical effects,e.g.,the Lau effect.In this paper,we propose the application of an LED array for realizing the Lau effect by taking into account the influence of the coherence properties of illumination on the Lau effect.Using spatially incoherent illumination with the LED array or a single LED,triangular distributed Lau fringes can be obtained.We apply the obtained Lau fringes in the optical lithography to produce analog structures.Compared to a single LED,the Lau fringes using the LED array have significantly higher intensities.Hence,the exposure time in the lithography process is largely reduced.

Beyond Pure Frequency and Phases Exploiting： Color Influence in SSVEP Based on BCl

A BCI （brain computer interface） established a new direct communication channel using the brain activity between the human brain and machine. The visual stimulus with a certain frequency is present to the BCI users; it exists in a particular condition to observe a continuous brain response respect to frequent of visual stimuli. A significant problem when engaged the SSVEP （steady-state visual evoked potential） based on BCI, it will be exhausted and may suffer for the users when staring at flashing stimuli. This experimental study investigates how the differences in LED＇s-colors influence of SSVEP with respect to （i.e., frequencies and phases）. The result shows that the visualization of phase delays in lower frequencies greater than in higher frequencies.

浅谈LED Array技术

红外线夜视技术早在20世纪60年代初期由美国贝尔实验室发明，期间经过了几次技术改进，自90年代末期开始有较大的发展，本文就红外线技术的现状及发展进行了探讨，并介绍了一种全新的红外技术。

Thermal analysis of LED lighting system with different fin heat sinks

This paper designs a 3 × 3 light emitting diode （LED） array with a total power of 9 W, presents a thermal analysis of plate fin, in-line and staggered pin fin heat sinks for a high power LED lighting system, and develops a 3D one-fourth finite element （FE） model to predict the system temperature distribution. Three kinds of heat sinks are compared under the same conditions. It is found that LED chip junction temperature is 48.978℃ when the fins of heat sink are aligned alternately.

The design and fabrication of a GaN-based monolithic light-emitting diode array

We report a new monolithic structure of GaN-based light-emitting diode （LED） which can be operated under high voltage or alternative current. Differing from the conventional single LED chip, the monolithic lightemitting diode （MLED） array contains microchips which are interconnected in series or parallel. The key chip fabrication processing methods of the monolithic LED array include deep dry etching, sidewall insulated protec- tion, and electrode interconnection. A 12 V GaN-based blue high voltage light emitting diode was designed and fabricated in our experiment. The forward current-voltage characteristics of MLEDs were consistent with those of conventional single junction light emitting diodes.