Optically controlling the emission chirality of microlasers

The orbital angular momentum (OAM) of light, emerging in helical light beams, is an unbounded degree of freedom that appears very advantageous for applications ranging from optical manipulation [1] to classical and quantum information multiplexing [2-4]. In this context, coherent sources of light carrying OAM are extremely appealing. Right now, one of the main limitations of integrated lasers generating OAM is their lack of versatility, as they rely on engineering chiral resonators [5], thus imposing a unique, non-tailorable chirality of the emission, i.e. clockwise (+|L|) or counter-clockwise (-|L|). Here, we propose and demonstrate, using a fully integrated device, a novel scheme where the chirality of a lasing mode carrying OAM can be optically controlled.