High-speed tunable and fixed-wavelength VCSELs for short-reach optical links and interconnects

This paper presents a review of recent work on high speed tunable and fixed wavelength vertical cavity surface emitting lasers (VCSELs) at Chalmers University of Technology. All VCSELs are GaAs-based, employ an oxide aperture for current and/or optical confinement, and emit around 850 nm. With proper active region and cavity designs, and techniques for reducing capacitance and thermal impedance, our fixed wavelength VCSELs have reached a modulation bandwidth of 23 GHz, which has enabled error-free 40 Gbps back-to-back transmission and 35 Gbps transmission over 100 m of multimode fiber. A MEMS-technology for wafer scale integration of tunable high speed VCSELs has also been developed. A tuning range of 24 nm and a modulation bandwidth of 6 GHz have been achieved, enabling error-free back-to-back transmission at 5 Gbps