1. Highly efficient optical antenna with small beam divergence in silicon waveguides
- Author
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Dan-Xia Xu, Pablo Ginel-Moreno, Pavel Cheben, J. Gonzalo Wangüemert-Pérez, Daniel Pereira-Martín, Jens H. Schmid, Abdelfettah Hadij-ElHouati, Alejandro Ortega-Moñux, Winnie N. Ye, Íñigo Molina-Fernández, Daniele Melati, Siegfried Janz, and Robert Halir
- Subjects
Beam diameter ,Materials science ,Silicon photonics ,business.industry ,Physics::Optics ,Metamaterial ,02 engineering and technology ,Grating ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Antenna efficiency ,law.invention ,010309 optics ,Optics ,law ,0103 physical sciences ,Antenna (radio) ,0210 nano-technology ,business ,Waveguide ,Beam divergence - Abstract
Optical antennas are key components in optical phased arrays for light detection and ranging technology requiring long sensing range and high scanning resolution. To achieve a narrow beam width in the far-field region, antenna lengths of several millimeters or more are required. To date, such long antennas have been impossible to achieve in silicon waveguides because currently demonstrated technologies do not allow accurate control of grating strength. Here, we report on a new type of surface-emitting silicon waveguide with a dramatically increased antenna length of L = 3.65 m m . This is achieved by using a subwavelength metamaterial waveguide core evanescently coupled with radiative segments laterally separated from the core. This results in a far-field diffracted beam width of 0.025°, which is a record small beam divergence for a silicon photonics surface-emitting device. We also demonstrate that by using a design with L -shaped surface-emitting segments, the radiation efficiency of the antenna can be substantially increased compared to a conventional design, with an efficiency of 72% at the wavelength of 1550 nm.
- Published
- 2020