High efficiency Bi2Te3-based thermoelectric materials and devices with energy conversion efficiencies of up to 6.0% under a temperature gradient of 217 K.

In the article the authors discuss light detection and ranging (LiDAR) for automotive applications and the potential roles Si photonics can play in practice. The authors review published research work on Si photonics optical phased array (OPA) and other relevant devices in the past decade with in-depth technical analysis with respect to practical system design considerations. The commercialization status of certain LiDAR technologies is briefly introduced.

An optical phased array (OPA), especially a two-dimensional (2D) OPA, suffers from the trade-off among steering range, beam width, and the number of antennas. Aperiodic 2D array designs currently aimed to reduce the number of antennas and reduce grating lobes within a wide range fall short when an aperture approaches millimeter size. A circular OPA design is proposed to address this issue. The circular design substantially reduces the number of antennas while achieving the same wide steering range and narrow beam width of optimized aperiodic 2D OPA designs. Its efficient suppression of grating lobes, the key to a wide steering range with minimal number of antennas and large antenna spacing, is theoretically studied and validated by simulation. The novel, to the best of our knowledge, design allows less than 100 antennas, orders of magnitude reduction, for millimeter size aperture OPA designs. It paves the way for commercialization by significantly reducing control complexity and power consumption.