Compact wavelength add-drop multiplexers using Bragg gratings in coupled dielectric-loaded plasmonic waveguides.

We report a novel design of a compact wavelength add-drop multiplexer utilizing dielectric-loaded surface plasmon-polariton waveguides (DLSPPWs). The DLSPPW-based configuration exploits routing properties of directional couplers and filtering abilities of Bragg gratings. We present practical realization of a 20-µm-long device operating at telecom wavelengths that can reroute optical signals separated by approximately 70 nm in the wavelength band. We characterize the performance of the fabricated structures using scanning near-field optical microscopy as well as leakage-radiation microscopy and support our findings with numerical simulations.

Near-field electrospinning of dielectric-loaded surface plasmon polariton waveguides.

Dielectric-loaded surface plasmon polariton waveguides (DLSPPWs) are typically made using nanolithography fabrication methods. In this paper we demonstrate that near-field electrospinning of polymer nanofibers directly onto a gold coated substrate can be used as an alternative method for rapid prototype fabrication of DLSPPWs. Surface plasmon polaritons (SPPs) have been excited directly inside the electrospun fibers using a prism in the Kretschmann-Raether configuration. A scanning near-field optical microscope (SNOM) was used to characterize the propagation of the excited SPP inside the polymer fiber demonstrating the potential for using electrospun polymer fibers as SPP waveguides.

Compact dipole nanoantenna coupler to plasmonic slot waveguide.

Optical nanoantennas can be used for coupling radiation to or from waveguides in analogy to micro- and radio-wave systems. In this letter we provide a systematic description of the design approaches for a coupler to a plasmonic slot waveguide in the telecom range around 1.55 µm with realistic excitation from a lensed optical fiber. We show that the best coupling efficiency of 26% can be achieved by utilizing a dipole antenna with side and bottom reflectors, and such coupling efficiency is 185 times larger than for the bare waveguide. The nanoantenna coupler provides a compact interface between an optical fiber and a plasmonic slot waveguide for future optical integrated circuits.