Chip-scale optical phased array for broadband two-dimensional beam steering at visible wavelengths

An optical phased array (OPA) on a chip, as a novel non-mechanical beam steering technique, has attracted much attention in various applications. However, due to the challenges in fabrication and the limited transparency window of the material for visible wavelengths, current OPAs are mainly focuses on the infrared wavelengths. Despite the progress, the visible light OPAs remain the challenges to not only simultaneously work in blue, green and red light, but also implement beam steering in two dimensions for the single-wavelength. In this paper, an 8-channel broadband OPA is demonstrated, which enables two-dimensional beam steering in visible light. Along the longitudinal direction, the beam steering angle of 0.7° at 585 nm is achieved by tuning phase shifts. Along the transverse direction, the demonstrated OPA implements beam steering angle of 4.49° at 585 nm by tuning polarization degrees and 25.97° at 488–610 nm by tuning wavelengths. Therefore, the demonstrated OPA holds significant promise for commercial applications such as visual projection and free-space optical communications.