An optical leaky wave antenna with Si perturbations inside a resonator for enhanced optical control of the radiation

Abstract

We investigate the directive radiation at 1550 nm from an optical leaky wave antenna (OLWA) with semiconductor perturbations made of silicon (Si). We study the radiation pattern dependence on the physical dimensions, number of perturbations and carrier densities in these semiconductor perturbations through optical excitations at a visible wavelength, 625 nm. In this detailed theoretical study we show the correlation between the pump power absorbed in the perturbations, the signal guided in the waveguide and the radiation through leakage. To overcome the limited control of the radiation intensity through excess carrier generation in Si, we present a new design with the OLWA integrated with a Fabry-Pérot resonator (FPR). We provide analytical and numerical studies of the enhanced radiation performance of the OLWA antenna inside the FPR, and derive closed-form formulas accounting for LW reflection at the edges of the FPR. A discussion on the constructive and destructive radiation by the direct and reflected leaky waves in the FPR resonator is provided. Results shown in this paper exhibit 3 dB variation of the radiation and pave the way for further optimization and theoretical developments.

Theory of a Directive Optical Leaky Wave Antenna Integrated into a Resonator and Enhancement of Radiation Control

“…Note that in [9] silicon perturbations were small thus enabling very fast control. Therefore the OLWA here analyzed is a good platform for optical antennas with beam control [25,26]. We prove that the OLWA integration into the FPR enhances the radiation and provides electronic tunability as high as 13.5 dB by using carrier injection.…”

“…We aim to enhance radiation level control thanks to the resonator by modifying the wavenumber of the guided leaky mode. Silicon is thus chosen as the waveguide material, because its refractive index can be modified by generating excess carriers (electrons/holes) through electronic injection or optical excitation (a detailed analysis can be found in [26]). The design, which is depicted in Fig.…”

Experimental demonstration of directive Si3N4optical leaky wave antennas with semiconductor perturbations at near infrared frequencies

“…6c, top). Though weak, it has been demonstrated that the tuning effect can be further boosted by integrating the OLWA with resonator topologies [11], [20], [25], such as a Fabry-Pérot resonator or a ring-resonator. High-quality factor resonators can be put into or pushed out of resonance by slight variations in the guided wavelength achievable with carrier modulation in Si inclusions, which in turn leads to modulation of the OLWA's radiation with a large extinction ratio.…”

“…In this paper, we present the experimental demonstration of a dielectric CMOS-compatible OLWA. Readers may refer to previous works [5], [11], [20] for further information on the theoretical design of OLWAs. Section 2 presents the fabrication of the OLWA.…”

Design of optical leaky wave antenna with circular and diamond Si perturbations for enhancing its performance

“…Directive radiation at 1550 nm for OLWA with semiconductor perturbed silicon waveguide is presented. As a result of correlation between input power absorbed in perturbations, signal guided in waveguide and leakage of radiation, the directive control of radiation can be obtained by integrating OLWA with Fabry‐Perot resonator . Not only in engineering field, nanoantenna are also applicable in medical diagnosis like protein detection, cancer detection, etc.…”