2D beam steering using phased array of MEMS tunable grating couplers

This paper describes a two-dimensional (2D) optical beam steering system using a one-dimensional (1D) optical phased array of 1D micro-electromechanical systems (MEMS) tunable grating couplers. Tuning the incremental phase difference β between the elements of an optical phased array is used to steer the beam in one direction (say, transverse). At the same time, the MEMS tuning of the individual grating couplers steers the beam in the perpendicular direction (longitudinal). A beam steering of ∼35° could be demonstrated along the transverse direction by varying β from −70° to 70°. The beam steering was ∼19° along the longitudinal direction by applying a potential difference of ∼ 1.6 volts to the MEMS tunable grating couplers. The beam width of the device with a mechanically and optically designed aperture of 100 μm × 100 μm is ∼ 1.75° × 0.82°. The beam width further reduces to ∼ 0.15° × 0.5° when the aperture increases to 1 mm × 0.2 mm. The 100 μm × 100 μm aperture supports a beam steering frequency of up to ∼ 50 kHz, comparable to the available state-of-the-art devices using other technologies like wavelength tuning (WT) and 2D phased arrays. The maximum voltage required by this MEMS is only around 1.6 volts, resulting in simple circuitry and low power consumption.