1550 Nm High Power Multi-junction VCSEL Design And Array Thermal Effect Researc

Currently,the market application of Vertical Cavity Surface Emitting Lasers(VCSELs)is becoming more and more widespread.Researchers have been highly interested in VCSELs due to their many advantages,such as small size,low cost,good beam quality,and easy integration.With Apple’s integration of VCSEL arrays into the Face ID module of its smartphones in 2017,the 3D sensing field has sparked a wave of enthusiasm.The wavelengths of VCSELs used in sensing applications are mostly 905 nm and 940 nm.To ensure eye safety,gratings or diffractive optical elements are used in the packaging to reduce the potential harm to human eyes.However,1550 nm VCSELs pose minimal risk to the human eye,but they suffer from low output power and significant thermal effects,making it difficult to meet the requirements for array design and application in sensing fields.Therefore,this thesis focuses on improving the output power,conversion efficiency,and alleviating the thermal effects of 1550 nm VCSEL arrays,and carries out the following work:First,by studying the theory of VCSEL quantum wells and tunnel junctions,multiple junctions are combined with 1550 nm to design multiple active region stacked structures in the VCSEL gain region.The impact of different junction numbers on important optoelectronic parameters such as device output power and conversion efficiency is analyzed.Different sizes of VCSELs are also designed to explore the relationship between size changes and device output power,threshold current,and other parameters.Finally,it is concluded that the 30 μm triple-junction VCSEL has better output characteristics,with an output power of about 1549 m W,a slope efficiency of about 1.55 W/A,and a peak conversion efficiency of up to 43%.Second,a size of 30 μm oxidized-confinement VCSEL is designed to analyze the impact of the position of the oxidation layer on the output characteristics of single and multiplejunction VCSELs.The device with high output power and conversion efficiency is obtained by optimizing the oxide aperture size.Finally,when the oxide aperture of the triple-junction VCSEL is 9 μm,the threshold current is only 1 m A,the slope efficiency is about 1.79 W/A,and the output power reaches 177.55 m W under 100 m A driving current,with a peak conversion efficiency of 37.5%.Third,using the 1550 nm oxidized-confinement triple-junction VCSEL as the unit device,three common array layouts are designed: square,equilateral triangle,and isosceles triangle.The impact of different layout methods and spacing on the thermal simulation results is analyzed,and their effect on the thermal effects of the array is discussed.In addition,a longitudinal structure is designed,which has an improved effect on the thermal diffusion and thermal crosstalk phenomena of the array.When the isosceles triangle layout is used with a spacing of 10 μm,the highest temperature of the array is reduced by about 1 ℃.This thesis combines multiple quantum well structures with oxide-confinement techniques to successfully design and simulate high-power 1550 nm VCSELs.Additionally,the thermal effects of different VCSEL arrays are discussed to improve their thermal diffusion and crosstalk.The research results presented in this thesis provide a theoretical basis for further studies on1550 nm VCSELs.