Four directional circular optical phased array for uniform two-dimensional beam steering at visible wavelength

Optical phased arrays (OPAs), owing to their remarkable capacity for rapid and precise beam steering, have emerged as a pivotal technology in various applications such as augmented reality, free-space optical communication, and optical imaging. In this paper, we present a 64-element two-dimensional (2D) circular OPA operating at a visible wavelength of 632.5 nm. To the best of our knowledge, this is the first time that 2D continuous beam steering with pure phase control has been realized at the visible wavelengths. We propose arrowhead antennas to reduce residual energy while maintaining the integrity of the far-field pattern. Furthermore, a four-directional array arrangement has been introduced to expand the field of view and enhance the uniformity of the side lobe suppression ratio (SLSR) at different azimuth angles. The measurement for the fabricated OPA shows 2D beam steering with an elevation angle of 9° and an azimuth angle of 360° with an SLSR of over 3 dB.