Silicon-based optical leaky wave antenna with narrow beam radiation

Abstract

We propose a design of a dielectric (silicon nitride) optical leaky wave antenna (OLWA) with periodic semiconductor (silicon) corrugations, capable of producing narrow beam radiation. The optical antenna radiates a narrow beam because a leaky wave (LW) with low attenuation constant is excited at one end of the corrugated dielectric waveguide. We show that pointing angle, beam-width, and operational frequency are all related to the LW complex wavenumber, whose value depends on the amount of silicon perturbations in the waveguide. In this paper, the propagation constant and the attenuation coefficient of the LW in the periodic structure are extracted from full-wave simulations. The far-field radiation patterns in both glass and air environments predicted by LW theory agree well with the ones obtained by full-wave simulations. We achieve a directive radiation pattern in glass environment with about 17.5 dB directivity and 1.05 degree beam-width at the operative free space wavelength of 1.55 μm, pointing at a direction orthogonal to the waveguide (broadside direction). We also show that the use of semiconductor corrugations facilitate electronic tuning of the radiation pattern via carrier injection.

Dirac leaky-wave antennas for continuous beam scanning from photonic crystals

“…15. The choice of these PC materials can be altered based on the frequency of operation (microwaves, terahertz or optical) and availability of material/technology, losses and so on.…”

“…LWAs have been traditionally used and extensively studied at microwaves [10][11][12] . But these structures offer capabilities that also make them excellent candidates for new frontiers in the terahertz, infrared and even optical applications 15 .…”

“…Continuous leaky structures such as slot waveguides are only capable of forward scanning above the cut-off (broadside) of the leaky mode 10 . Periodically perturbed waveguides, such as periodically loaded dielectric waveguides 15,16 are capable of both forward and backward scanning away from broadside, but typically have an open stopband around broadside due to mode coupling 10,17 . Hence, such structures so far could never achieve true broadside radiation and could only radiate 'close' to broadside 10 .…”

“…Such structures are extremely useful for reliable leaky-wave operation, especially at higher frequencies beyond microwaves. Some dielectric based and optical LWAs have been reported thus far in the literature 15,16,24,25 , which, however, all suffer from the broadside open stopband issue.…”

Highly Directive Hybrid Plasmonic Leaky Wave Optical Nano-Antenna

“…The antenna designed here transforms a guided mode into a radiation mode, thus having a vertical radiation pattern. The developed antenna benefits from high directivity advantage of leaky-wave antennas, and low loss properties and confinement of hybrid plasmonic structures, thus having a higher efficiency than plasmonic antennas [14,18,19], and a smaller size than dielectric antennas [20,21]. To be able to integrate the optical antenna with other elements in an opto-electronic circuit, the antenna is designed in such a way to be fabricated by standard CMOS fabrication techniques.…”