In(Al)GaAs–AlGaAs Wafer Fused VCSELs Emitting at 2- $\mu$m Wavelength

We demonstrate 2-mum wavelength, wafer-fused In(Al)GaAs-InP-AlGaAs-GaAs vertical-cavity surface-emitting lasers (VCSELs) emitting single-mode power of 0.5 mW at room temperature with a threshold current of 4 mA and sidemode suppression ratio of over 30 dB. These devices can be continuously tuned with current by 5 nm without mode hopping, with a tuning rate of 0.31 nm/mA. These features demonstrate the potential of these long wavelength VCSELs for gas sensing and other optical spectroscopy applications.