Search results for "Optoelectronics"

Superconductivity suppression in Fe-implanted thin Al films

2005

At present, ion implantation into metallic systems is given increasing attention, aiming at achieving properties and functionalities of technologically valuable materials not easily available via conventional techniques. In our experiments thin Al films were implanted with Fe ions in order to find out how the superconductive properties of the metal can be modified at will. The purpose was twofold, viz., first, to study the basic physics of superconductivity in low-dimensional metallic structures doped with impurities. The second purpose was to apply ion implantation for the suppression of undesired superconductivity in aluminum widely used for fabrication of micro- and nanodevices operated …

Fabrication of Quasi-One-Dimensional Superconducting Micro- and Nanostructures

2007

Wires capable of conducting electric current are basic blocks of all electronic applications. Of particular interest for nanoelectronics are superconducting elements taking advantage of the superconductor's macroscopic quantum coherence and zero resistance. Recently there appeared indications that due to quantum fluctuations the dissipationless electric current (supercurrent) can be suppressed in ultra-narrow superconducting channels with the effective diameter below approximately 10 nm. In this Review we will describe methods of fabrication of quasi-one-dimensional superconducting micro- and nanowires suitable for electric transport measurements at cryogenic temperatures. In the first sect…

Superconducting nanowire quantum interference device based on Nb ultrathin films deposited on self-assembled porous Si templates

2014

Magnetoresistance oscillations were observed on networks of superconducting ultrathin Nb nanowires presenting evidences of either thermal or quantum activated phase slips. The magnetic transport data, discussed in the framework of different scenarios, reveal that the system behaves coherently in the temperature range where the contribution of the fluctuations is important.

High quality superconducting titanium nitride thin film growth using infrared pulsed laser deposition

2018

Superconductor-Diamond Hybrid Quantum System

2016

This chapter describes recent progress on research into superconducting flux qubit, NV diamond, and superconductor-diamond hybrid quantum systems. First, we describe important physical properties of superconducting macroscopic artificial atoms i.e., the tunability of the qubit energy level spacing, the coherence property, an example of strong coupling to another quantum system such as an LC harmonic oscillator, and qubit state readout through a Josephson bifurcation amplifier. We then introduce the NV center in diamond as an intriguing candidate for quantum information processing, which offers excellent multiple accessibility via visible light, microwaves and magnetic fields. Finally, we de…

Highly sensitive superconducting circuits at ∼700 kHz with tunable quality factors for image-current detection of single trapped antiprotons

2016

We developed highly-sensitive image-current detection systems based on superconducting toroidal coils and ultra-low noise amplifiers for non-destructive measurements of the axial frequencies (550$\sim$800$\,$kHz) of single antiprotons stored in a cryogenic multi-Penning-trap system. The unloaded superconducting tuned circuits show quality factors of up to 500$\,$000, which corresponds to a factor of 10 improvement compared to our previously used solenoidal designs. Connected to ultra-low noise amplifiers and the trap system, signal-to-noise-ratios of 30$\,$dB at quality factors of > 20$\,$000 are achieved. In addition, we have developed a superconducting switch which allows continuous tu…

Optical near-field microscopy of light focusing through a photonic crystal flat lens

2008

We report here the direct observation by using a scanning near-field microscopy technique of the light focusing through a photonic crystal flat lens designed and fabricated to operate at optical frequencies. The lens is fabricated using a III-V semiconductor slab, and we directly visualize the propagation of the electromagnetic waves by using a scanning near-field optical microscope. We directly evidence spatially, as well as spectrally, the focusing operating regime of the lens. At last, in light of the experimental scanning near-field optical microscope pictures, we discuss the lens ability to focus light at a subwavelength scale.

Semiconductor optical waveguide devices modulated by surface acoustic waves

2019

Second-harmonic generation in surface periodically poled lithium niobate waveguides:On the role of multiphoton absorption

2008

Second harmonic generation is investigated in lithium niobate channels realized by proton exchange and quasi-phase-matched by surface periodic-poling. The reduction in conversion efficiency at high powers is interpreted in terms of multi-photon absorption via two-color terms, yielding an estimate of the dominating three-photon process.

Luminescence of the surface nonbridging oxygen hole center in silica: Spectral and decay properties

2008

We investigated the red luminescence in a porous film of silica nanoparticles, originating from surface nonbridging oxygen hole centers. The excitation spectrum was measured from 1.8 to 8.0 eV by a tunable laser system and a synchrotron radiation source; this spectrum evidences a peak at 2.0 eV, nearly overlapping with the emission, and an ultraviolet broadband with peaks at 4.8 and 6.0 eV. The emission is characterized by a spectrum with two subbands split by 0.07 eV, its decay occurs with lifetime longer than 30 microsec and undergoes a thermal quenching by a factor aboout 2 with increasing temperature from 10 to 290 K. The optical characteristics of surface and bulk centers are discussed…