Design of a compact CMOS-compatible photonic antenna by topological optimization

Abstract

Photonic antennas are critical in applications such as spectroscopy, photovoltaics, optical communications, holography, and sensors. In most of those applications, metallic antennas have been employed due to their reduced sizes. Nevertheless, compact metallic antennas suffer from high dissipative loss, wavelength-dependent radiation pattern, and they are difficult to integrate with CMOS technology. All-dielectric antennas have been proposed to overcome those disadvantages because, in contrast to metallic ones, they are CMOS-compatible, easier to integrate with typical silicon waveguides, and they generally present a broader wavelength range of operation. These advantages are achieved, however, at the expense of larger footprints that prevent dense integration and their use in massive phased arrays. In order to overcome this drawback, we employ topological optimization to design an all-dielectric compact antenna with vertical emission over a broad wavelength range. The fabricated device has a footprint of 1.78 µm × 1.78 µm and shows a shift in the direction of its main radiation lobe of only 4° over wavelengths ranging from 1470 nm to 1550 nm and a coupling efficiency bandwidth broader than 150 nm.

Breaking FOV-Aperture Trade-Off With Multi-Mode Nano-Photonic Antennas

“…However, since the antenna is fed from one side, the field distribution might deviate from an ideal periodic pattern. While using a grating structure is a straight forward technique to achieve a distribution, other designs obtained by aperiodic and irregular apertures have been also demonstrated recently [4], [18], [25].…”

“…1). Nano-photonic antennas have application in many recently demonstrated integrated photonic systems such as optical phased array transmitters [1]- [4], [18], [19] and receivers [7], [12], nano-photonic coherent imager [13], wireless optical communication [14], lens-less cameras [16], [17], etc. For implementing most of today's low cost, high-yield, and commercial systems, silicon photonic integration technology with a single photonic layer of silicon R. Fatemi, P. P. Khial, A. Khachaturian, and A. Hajimiri are with the Department of Electrical Engineering, California Institute of Technology, Pasadena, CA 91125 USA e-mail: (sfatemi@caltech.edu).…”

“…Deviating from grating structures allowed to achieve higher radiation efficiency [4]. Moreover, an ultra-compact broadband antenna is realized via optimization of the silicon slab etching pattern [18]. In addition to devising novel antenna structures on a single photonic layer process, by adding a high contrast grating on top of the antenna structure [8] and bottom reflectors [6], [10] the radiation efficiency of the antenna is improved significantly.…”

Design of Compact and Efficient Silicon Photonic Micro Antennas With Perfectly Vertical Emission

“…However, other limitations still exist. Dimensions of SOI surface gratings are typically on the order of few tens of microns and a significant size reduction is not easy to achieve without compromising efficiency [11]. This can be a limiting factor for applications requiring a high integration density, e.g.…”

Optimization of Element Positions in Linear Optical Phased Arrays for Broad Beam Steering Operation

“…In order to overcome this drawaback, all-dielectric antennas were developed [5]. In particular, complementary metal oxide semiconductor (CMOS)-compatible silicon PAs have emerged as a high potential solution because, on the one hand, they take advantage of the mature manufacturing infrastructure and, on the other hand, can be naturally integrated with other constitutive blocks [6].…”