Research Of Optical Devices On Transmitting And Receiving In Wireless Light Communication

Along with the developing of existing communication,the new type of communication technology with high transmission rate and green becomes the research hotspot.Compared with traditional communication technology,Wireless Optical Communication(WOC)can save energy and protect environment better,has no radiation to human body.Furthermore,WOC has high security,abundant bandwidth resources,high transmission rate and no need to apply for spectrum authorization,and wouldn't interfere with other bands.In the WOC,Visible Light Communication(VLC)is a vital part and a rising communication technology and based on LED high frequency flicker for the data transmission.VLC possesses two kinds of function,illumination and data transmission,In the WOC,because of the large divergence angle of light source,the signal will be attenuated and can't arrive the reception terminal effectively.It is also a problem that reception angle of receving antenna is so small to weak focusing ability.Therefore,the important problems we are facing are to improve the transmitted power,enlarge the angle of reception,and enhance the focusing efficiency.For solving the problems,this paper design three kinds of optical element.The main work of the paper contains,For improving the efficiency and integration of receiving terminal in VLC system,we designed a double face Fresnel lens with high efficiency.In VLC system,the reception component demands microminiaturization,high integration and focusing efficiency.To reduce the size and increase focusing efficiency,a new receiving antenna,the Fresnel lens with double-faced tooth,is designed,which is based on the traditional VLC receiving antenna,the Fresnel lens with single-faced tooth.This paper shows the design method and simulated result of proposed reception antenna.The calculated results are compared with focusing efficiency and F number of traditional Fresnel lens.It is found that the proposed lens with higher focusing efficiency,smaller size,spot and focal length can improve the integrating andreceiving power of receiving system.Aiming at large divergence angle and low energy efficiency of LED,we designed an LED collimating lens with a free-form surface.Due to high electrooptical conversion efficiency,low energy consumption,low heat generation,long life,and small size,etc.,LED light source is widely used in many industries and fields.The LED is a Lambertian-typed light source which is a double blades,the drawback or advantage for some applications.Thus,it is always an important topic to meet the design of light distribution components in various fields.In the WOC system,because the large divergence angle of Lambertian-typed light source would influence the transmission efficiency,this paper design two kinds of LED collimation system with free-form surface based on planoconvex lens and meniscus lens,and optics simulation and parameters comparison are also performed.To improve the light-guide efficiency and uniformity of illumination,basing on traditional light-guiding pipe,this paper designs a new structure of light pipe including a cylinder and a circular truncated cone.The design theory and method of new light pipe is given in the paper.Aiming at three kinds of divergence angle LED,we design different light-guide pipe made by PC and use rays tracing method to study the light-guide characteristics of two kinds of light-pipe.The results show that this new type of pipe can keep high transmission efficiency and good uniformity of illumination.Compared with traditional light-pipe,this pipe has a 90% improvement in light efficiency,86% increase in average irradiance and a better uniformity of illumination.The new type of light-pipe is easy to process and have a high light-guide efficiency and illuminating uniformity,which plays an important role in light guidance,short distance communication and display of LED.