Generating and identifying optical orbital angular momentum with silicon photonic circuits

Here, we propose and demonstrate a silicon nanophotonic phased array that is capable of generating light carrying optical orbital angular momentum (OAM). Optical beams carrying different orbital angular momenta have been generated. In addition, the generated OAM wavefronts are experimentally identified by interfering with another on-chip generated Gaussian beam, opening up opportunities of integrating conventional optical systems and functionalities on to a silicon chip.