Calculation and analysis of 850nm high speed vertical cavity surface emitting lasers

• Main Authors: Chun-Yi Lu, 呂俊毅
• Other Authors: Shing-Chung Wang
• Format: Others
• Language: en_US
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/24902893951809849977

碩士 === 國立交通大學 === 光電工程系所 === 92 === This research is focusing on the study of high speed modulation characteristics of GaAs base vertical cavity surface emitting laser (VCSEL) with oxide-confined and oxide-implant structure, and establishes an equivalent circuit model for electrical characteristic analysis. The 850nm VCSEL structure consists of GaAs /AlGaAs multi-quantum-well. Top and bottom distributed bragg reflector has 22 and 32 pairs Al0.15Ga0.85As /Al0.9Ga0.1As respectively. We setup an on-wafer high speed measurement system which benefits us to test device immediately and avoid modulation limitation from package. Proton implant process is a simple method to reduce parasitic capacitance. For this, we fabricate oxide-only and oxide-implant VCSEL and compare with their modulation characteristics. With same oxide aperture size 8µm, oxide-implant VCSEL has better modulation bandwidth 8.4 GHz and oxide-only VCSEL has 2.3 GHz. Then we compare oxide-implant VCSEL with different oxide aperture size as 6, 7 and 8µm, and obtain modulation current efficiency factor (MCEF) as 3.06, 5.54 and 5.96 GHz /mA1/2 respectively. We build an equivalent circuit model, corresponding different VCSEL structure, for modeling the modulation limitation, affected by RC circuit, and simulate circuit by Agilent Advanced Design System software. The simulation results could make the modulation limitation clearly and help us to modify the VCSEL process for high speed operation.