High-performance surface grating couplers for fiber-chip and free-space coupling

Abstract

Surface grating couplers are key components in silicon photonics, as they act as efficient fiber-chip and free-space optical interfaces. Here we review some of our latest advances in these devices, including fiber-chip zero-order grating couplers achieving the highest coupling efficiency–bandwidth product reported to date, single-beam fiber-chip couplers with -0.2 dB coupling loss, single-beam optical antennas yielding nearly 100% directionality and ultra-fast beam steering, and apodized-imaging fiber-chip couplers that focus the radiated light at millimeter-scale distances above the chip surface.