Integrated Optical Phased Array Based Large Angle Beam Steering System Fabricated on Silicon-on-Insulator

In this paper, we present a highly compact silicon nano-membrane based optical phased array fabricated using conventional CMOS processing on silicon-on-insulator that provides for over 10 degrees of beam steering in a silicon slab lambda=1.55 mu m using transverse-electrical polarized light. A low loss 1-to-12 multi-mode interference (MMI) optical beam splitter with high uniformity is used to provide inputs to the optical phased array. Using an unequally spaced waveguide array permits us to relax the half-wavelength spacing requirement for large angle beam steering, thereby avoiding the optical coupling between adjacent waveguides and reducing the side-lobe-level of the array radiation pattern. S-bend waveguides convert the equally spaced MMI output to the unequally spaced wave guide array, while passively equalizing the phases of each array element to compensate for the MMI output phase profile. Independently controllable thin film metal heaters are used to achieve phase shifting using the strong thermo-optic response of silicon. Heat-insulating air grooves minimize thermal crosstalk, while also achieving and low power consumption.