Photonic Microsystems Group
Prof. Mike Watts


Research Area I: Phased Arrays


Phased Arrays phaseArray_1 lidar_000


1. Active Tuning of an 8×8 Nanophotonic Phased Array

2. Active Tuning of Beam Steering throughout 51 Degree Angle

3. Continuous Tuning of Orbital Angular Momentum (OAM) State

Microphotonics is in its infancy with nearly all demonstrations to date being formed from single elements. However, much like microelectronics, the true power of microphotonics will come from system-level demonstrations. The first large-scale system demonstration of microphotonic elements was the polarization independent circuit that was designed and demonstrated back in 2007. While this early circuit contained ~30 microphotonic elements, our group has recently extended microphotonic circuit complexity significantly with the demonstration of the largest optical phased array and largest silicon photonic circuit ever produced (left and middle figure). By further incorporating heaters directly into the silicon waveguides themselves, a departure from traditional overclad heaters, our group was able to demonstrate phase shifters and tunable filters that were much faster, much more efficient, and much more compact, than any prior result. The heater was further applied to problem of optical beam steering (right figure) and orbital angular momentum (OAM) generation (Video. 3) using optical phased arrays. Moreover, the phased arrays are truly holographic, and if pushed into the visible would enable true three-dimensional holographic displays. More generally, this demonstration represents the first very large-scale integrated photonic demonstration of any kind, with over 12,000 optical elements and reveals Moore’s Law-like growth rates in circuit complexity, opening up the possibility for mega-scale microphotonic circuits in the near future.