On‐Chip Metamaterial Antenna Array with Distributed Bragg Deflector for Generation of Collimated Steerable Beams
Pablo Ginel‐Moreno, Abdelfettah Hadij‐ElHouati, Alejandro Sánchez‐Postigo, J. Gonzalo Wangüemert‐Pérez, Íñigo Molina‐Fernández, Jens H. Schmid, Pavel Cheben, Alejandro Ortega‐Moñux
Abstract
Abstract The generation of collimated steerable beams of light is a fundamental function in optics needed in many applications, including free‐space optical communications, remote sensing, and light detection and ranging. Implementing large‐aperture light emitters directly on a photonic integrated chip without using external optics and expensive alignment systems is an outstanding challenge in integrated photonics. Here, the experimental demonstration of a new integrated antenna array architecture that uses a compact feeding circuit is reported. The design is based on an apodized Bragg deflector working as a low‐loss (<0.3 dB) ultra‐compact beam expander, which generates a 40‐µm‐wide on‐chip Gaussian beam that illuminates a one‐dimensional array of 112 optical antennas with a length of 1.5 mm. Each antenna comprises a metamaterial subwavelength grating waveguide core that is laterally loaded with an array of periodic radiative silicon segments. The device is fabricated on a 220‐nm silicon‐on‐insulator platform using a single etch process with a minimum feature size of 80 nm. An antenna array with a power gain of 50 dB, a radiation efficiency of −3.8 dB, and a far‐field angular divergence of 1.8° × 0.2°, in a wavelength range of 1500–1580 nm is presented.