A method for the fabrication of bow-tie optical antennas at the apex of pyramidal Si3N4 atomic force microscopy tips is described. We demonstrate that these novel optical probes are capable of sub-wavelength imaging of single quantum dots at room temperature. The enhanced and confined optical near-field at the antenna feed gap leads to locally enhanced photoluminescence (PL) of single quantum d...

This work presents the design of a wideband circular tightly coupled array for omnidirectional pattern generation. The proposed works over an 8:1 bandwidth, providing very high performance in terms active reflection coefficient, realized gain, and patterns with reduced ripples. is composed 32 low-profile, self-complementary, bow-tie elements displaced around metallic mast. capacitive coupling b...

Ge-on-Si plasmonics holds the promise for compact and low-cost solutions in manipulation of THz radiation. We discuss here plasmonic properties doped Ge bow-tie antennas made with a low-point cost CMOS mainstream technology. These display resonances between 500 700 GHz, probed by time domain spectroscopy. show surface functionalization thin layer α-lipoic acid that red-shifts antenna about 20 G...

We describe measurements of the angular radiation patterns from lens-coupled terahertz antennas fabricated on photoconductive substrates. These measurements have been performed using a novel terahertz time-domain spectrometer in which the femtosecond optical pulses used to gate the emitter and receiver antennas are delivered via optical fiber. We have used this system to perform a comparison be...

Terahertz radiation was generated with several designs of photoconductive antennas (three dipoles, a bow tie, and a coplanar strip line) fabricated on low-temperature-grown (LT) GaAs and semi-insulating (SI) GaAs, and the emission properties of the photoconductive antennas were compared with each other. The radiation spectrum of each antenna was characterized with the photoconductive sampling t...

Plasmonic nanoantennas are efficient devices to concentrate light in spatial regions much smaller than the wavelength. Only recently, their ability to manipulate photons also on a femtosecond time scale has been harnessed. Nevertheless, designing the dynamical properties of optical antennas has been difficult since the relevant microscopic processes governing their ultrafast response have remai...

Mastering dynamic free-space spectral control and modulation in the near-infrared (NIR) and optical regimes remains a challenging task that is hindered by the available functional materials at high frequencies. In this work, we have realized an efficient metadevice capable of spectral control by minimizing the thermal mass of a vanadium dioxide phase-change material (PCM) and placing the PCM at...