Thermal Analysis and Optimization of Vertical-cavity Surface-emitting Lasers with Different Packaging Structures
Vertical-cavity surface-emitting laser (VCSEL) is easily integrated on-chip and is a key optoelectronic device in systems such as laser radar and security lighting.However,the severe self-heating phenomenon can affect the output power,high-speed characteristics,and stability of the devices.Therefore,thermal management technolo-gy is extremely important,and adopting an optimized packaging approach can effectively increase the heat dissipa-tion of VCSELs,which is an important method to improve VCSELs' thermal performance.This article is based on a finite element method (FEM) computational model to numerically analyze the thermal characteristics of VCSELs with different packaging methods and a thin copper layer covering the devices' surface.The simulation results indicate that compared to the top-emitting packaging method,the flip-chip packaging with substrate-emitting (fully etched top and bottom DBR) can effectively reduce the active region temperature,with a reduction rate exceeding 56％.As the device mesa diameter gradually increases,devices using the top-emitting packaging method show a decreasing trend in temperature and thermal resistance,with a temperature reduction 50 ℃ and the thermal resistance reduction of over 3.25 K/mW.However,devices with a fully etched top and bottom DBR structure using flip-chip packaging and devices with only etched P-DBR structure using flip-chip packaging both exhibit a slowly increasing trend in tempera-ture and thermal resistance,with temperature increases of 2 ℃ and thermal resistance increases of 0.15 K/mW.Cov-ering the device mesa,sidewalls,and substrate surfaces with a layer of copper can effectively reduce the temperature of the active region.When the thickness of the copper layer is 3 μm,the temperature reduction of the active region is 43％ and thermal resisitance reduction is 1.9 K/mW.This article analyzes the impact of packaging methods on the thermal characteristics of VCSELs and proposes optimization solutions,which have guiding significance for the effec-tive thermal packaging of VCSELs.
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