Printed-circuit-board linear Paul trap for manipulating single nano- and microparticles.

Levitation of very small but macroscopic objects is a rapidly developing interrogation technique for nanooptics and optomechanics. Paul traps are one mechanism for levitation of charged particles, which enables interrogation of novel materials or optically active samples in a virtually interaction-free environment, providing a test-bed for completely new experiments. Elementary traps have already been demonstrated for nano- and microparticles as a proof-of-principle for such experiments.

Limitations of Particle-Based Spasers.

We present a semiclassical analytic model for spherical core-shell surface plasmon lasers. Within this model, we drop the widely used one-mode approximations in favor of fully electromagnetic Mie theory. This allows for incorporation of realistic gain relaxation rates that so far are massively underestimated.

On-demand electrostatic coupling of individual precharacterized nano- and microparticles in a segmented Paul trap.

We present a novel versatile method for one-by-one coupling of single nano- and microparticles. The particles are levitated in a segmented linear Paul trap, which is ideal for fast particle characterization and assembly of two or more preselected particles by electrostatic attraction. The final compound particles remain in the trap or can be deposited on other structures.

Broadband linear high-voltage amplifier for radio frequency ion traps.

We developed a linear high-voltage amplifier for small capacitive loads consisting of a high-voltage power supply and a transistor amplifier. With this cost-effective circuit including only standard parts sinusoidal signals with a few volts can be amplified to 1.7 kVpp over a usable frequency range at large-signal response spanning four orders of magnitude from 20 Hz to 100 kHz under a load of 10 pF.

In situ observation of plasmon tuning in a single gold nanoparticle during controlled melting.

In this Letter we study the relations among shape, symmetry, and plasmon resonance shift in a single gold nanoparticle during laser melting. A beam of an argon ion laser is focused on a selected particle, while its optical and shape properties can be observed with the help of a combined dark-field/photoluminescence microscope and an atomic force microscope, respectively. Starting from a spherical shape, radiation pressure forms the melting gold particle into an upright standing rod on a glass substrate, showing a characteristic dipole scattering pattern.

Soft-landing and optical characterization of a preselected single fluorescent particle on a tapered optical fiber.

Tapered optical fibers offer easy access to the evanescent field of their guided modes which is ideal for sensing applications. We introduce a soft-landing technique utilizing a linear Paul trap to select and place a single microparticle on the surface of a tapered optical fiber. This approach allows on-demand functionalization of fragile nanophotonic components with arbitrary particles, e.