Intensity and polarization dynamics in ultrafast birefringent spin-VCSELs

Since todays Internet traffic is more and more concentrated in hyperscale datacenters,1 new concepts for shortrange optical communication systems with high modulation bandwidth, high temperature stability, and low energy consumption are urgently needed. Birefringent spin-lasers, in particular spin-controlled vertical-cavity surface-emitting lasers (spin-VCSELs), are a novel type of ultrafast laser devices which promise to serve as ultrafast transmitters for the next generation of optical communication systems. While current-driven intensitymodulated VCSELs are state-of-the-art laser devices for short-range communication, their modulation bandwidth is limited to values below 40 GHz.2, 3 Recently, we were able to demonstrate that modulating carrier spin and light polarization in spin-VCSELs instead of carrier density and light intensity in conventional devices enables ultrafast polarization dynamics and a modulation bandwidth of more than 200 GHz.4 This high modulation bandwidth was achieved by increasing the resonance frequency of the coupled carrier spin-photon system by implementing high values of birefringence to the cavity of 850 nm GaAs/GaAlAs VCSELs. Here, we show experimental results for the intensity and polarization dynamics in highly birefringent spin-VCSELs as a function of bias current, birefringence, and temperature and demonstrate the capability of spin-VCSELs for ultralow energy consumption and high temperature stability. Furthermore, we present first results on polarization dynamics in 1.3 μm VCSELs for potential long-range communication systems and discuss novel concepts for future integrated and electrically pumped devices.