VCSELs take control

A vertical-cavity surface-emitting laser (VCSEL) that is capable of controlled switching between different polarisation states has been demonstrated by researchers at the University of California Santa Barbara (UCSB). The US-based team showed that, by changing the direction of the current injection in a specially designed dual intra-cavity contacted VCSEL, the output polarisation can be switched between two states. They also achieved a record low threshold current of 0.19 mA and a record high extinction ratio of >21 dB for a polarisation modulation device. The compact VCSEL with polarisation control shows promise for enhancing the performance of imaging and sensing systems.