Impact of Oxide Aperture on the Static and Dynamic Performance of 850-nm VCSELs

We fabricate 850-nm vertical-cavity surface-emitting lasers (VCSELs) with oxide-aperture diameters of 5, 7, 9 and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$11~\mu $ </tex-math></inline-formula>m and study the effect of oxide-aperture size on the threshold current, output power, differential quantum efficiency and wall-plug efficiency of the devices. We characterize the small-signal modulation bandwidth (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f} _{3dB}$ </tex-math></inline-formula>) of the devices and explore the impact of oxide-aperture size and bias current on the modulation bandwidth. We analyze the relationship between electrical power and the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f} _{3dB}$ </tex-math></inline-formula> of the VCSELs with different aperture diameters. The fabricated 850-nm VCSEL with the oxide-aperture diameter of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7~\mu $ </tex-math></inline-formula>m at room temperature shows a maximum <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f} _{3dB}$ </tex-math></inline-formula> of nearly 20 GHz and an output power of 9.09 mW. When the oxide-aperture increases to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$11~\mu $ </tex-math></inline-formula>m, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f} _{3dB}$ </tex-math></inline-formula> remains above 17 GHz and the optical output power exceeds 14 mW.