Optical beam steering using surface micromachined gratings and optical phased arrays

Two categories of optical beam steering micro-electro-mechanical systems (MEMS) were investigated: variable blaze gratings (VBGs) and linear optical phased arrays. All devices were surface micromachined using the Multi-User MEMS Processes (MUMPs). VBGs use an adjustable blaze angle to direct the majority of reflected light into a selectable diffraction order. Diffraction efficiencies greater than 50% were demonstrated. Linear optical phased arrays use a single row of piston micromirrors to create a far-field pattern with a steerable main lobe along one axis. All devices were constructed of polysilicon and gold and were actuated with electrostatic force. Electrostatic actuation provides high speed operation at a very low drive power. These optical beam steering devices discussed in this work are less optically efficient than a single pivoting mirror, but they require no post-fabrication assembly and can handle large beam diameters. Also, the low individual mass of the elements in surface micromachined VBGs and optical phased arrays yields faster system response times than a single macroscaIe pivoting mirror.