Functional Plasmonic Nanocircuits with Low Insertion and Propagation Losses

Abstract

We experimentally demonstrate plasmonic nanocircuits operating as subdiffraction directional couplers optically excited with high efficiency from free-space using optical Yagi-Uda style antennas at lambda(0) = 1550 nm. The optical Yagi-Uda style antennas are designed to feed channel plasmon waveguides with high efficiency (45% in coupling, 60% total emission), narrow angular directivity (<40 degrees), and low insertion loss. SPP channel waveguides exhibit propagation lengths as large as 34 mu m with adiabatically tuned confinement and are integrated with ultracompact (5 x 10 mu m(2)), highly dispersive directional couplers, which enable 30 dB discrimination over Delta lambda = 200 nm with only 0.3 dB device loss

Extremely confined gap surface-plasmon modes excited by electrons

“…Finally, it should be stressed that the MIM aGSP mode excitation should be expected to occur at any asymmetric junction/bend of GSP-based (gap or slot) plasmonic waveguides typically used in various plasmonic circuits 31,40,41 . The aGSP mode absorption thereby represents an additional (efficient) channel of energy dissipation that should be taken into account in the design of plasmonic nanophotonic circuits and devices.…”

Negative refraction due to discrete plasmon diffraction

“…This causes discrete diffraction inside the array, which acts as a highly anisotropic 2D metamaterial. For a single waveguide coupler with this design we demonstrated a shortest achievable coupling length of only 2.45 μm, compared to typically millimeters in dielectric photonics and with a high spectral dispersion that is governed by the dispersion of the metal filaments between the waveguides [6]. Here we observe that the field distribution inside the array causes a laterally diverging intensity distribution with two distinct maxima at the diverging outer bounds at the distance W a from the excited center waveguide (Fig.…”

“…1a,b) that is excited with a highly focused laser beam with a continuously scanned wavelength via acousto-optical tunable filters (λ 0 = 1200 -1800 nm) via a connected Yagi-Uda nanoantenna (Fig. 1b and c) with a power conversion efficiency of 15% and a typical propagation length of 30 μm [6]. When this feed waveguide enters the array the mode of this first waveguide evanescently couples to the modes of the adjacent waveguides.…”

Proposal of multiple-slot silica high-mesa waveguide for infrared absorption

“…Firstly, so far, several types of waveguide structures have been proposed for infrared sensing, such as the hollow [10,11] and the slot [12,13] structures. Compared with the hollow structure, the slot structure is attractive for realizing a smaller radius of curvature [14,15], which is helpful for realizing high-density integration. Secondly, among several types of slot waveguides, the slot waveguide using a high-mesa structure [16] is useful because it offers a higher portion of an optical field's profile inside the slot region than the others [17].…”