Design And Performance Analysis Of Integrated Optical Waveguides Based On GaN-LED And Grating

LED is a semiconductor light emitting device based on the p-n junction's electroluminescence.Compared with the traditional lighting source such as incandescent and halogen,LED has the advantages of high efficiency,long service life,energy conservation,environmental protection and so on.It is known as the green lighting source in twenty-first Century.Due to the limitation of total reflection,the light extraction efficiency of the traditional LED is too low,thus improving the extraction efficiency of LED is a technical bottleneck for the power type LED.Optical fiber,as the most common optical waveguide,has become the new favorite of lighting technology because of its high design freedom,safe and reliable use,long life and simple maintenance.The basic principle of optical fiber lighting is to combine the optical coupling of the light source into the optical fiber through the coupling device,and use the optical properties of the optical fiber to realize the transmission and lighting of the light.Combining LED with fiber lighting technology is the trend of fiber optic lighting nowadays,which combine the advantages of semiconductor lighting and fiber lighting.This paper first improves the LED structure to improve its luminous efficiency,and then designs the LED-fiber coupling system;at last the structure parameter and the properties of the LED and the LED-fiber coupling system were simulated and analysized.The main content of the full text is summarized as follows:(1)The overview of GaN materials,the history and characteristics of its development,the history of LED development and the research about the improvement of the efficiency are introduced.(2)The theoretical method of FDTD is introduced and the optical extraction efficiency of the GaN-LED is calculated based on the finite difference time domain method.(3)The traditional LED and the flip chip structure are simulated.Then the inverted LED structure and grating integrated device are simulated based on RSOFT software,and the structure of the grating is optimized by changing the height and width of the grating according to the calculation results.The simulation results show that the optical efficiency of the traditional LED structure can be greatly improved,and the effect of the sensitive change of the thickness of the p-GaN on the efficiency of the light output is also reduced.(4)Through a theoretical analysis,two kinds of LED optical fiber coupling system structure are designed with ZEMAX software,and the by initial parameters of the structure are calculated according to the geometrical optics property.By optimizing the thickness and radius of the optical elements,the best coupling efficiency is obtained.Finally,by analyzing the dot matrix and energy map of analysis in ZEMAX,the exact size and energy distribution of the dispersion spot RMS are obtained.