Optical manipulation of CuCl nanoparticles under an excitonic resonance condition in superfluid helium

Abstract

In order to prepare the optimal condition for the resonant optical manipulation, a lot of CuCl particles with a broad size-distribution ranging from 10 nm to 10 µm have been directly fabricated from a bulk sample by laser ablation in superfluid helium. We irradiated these particles with the laser light covering the excitonic resonance levels of particles smaller than 100 nm in order to transport them onto a target silicon substrate by using resonant radiation force. As a result, we have observed that many particles of from 10 to 50 nm diameters adhere to the substrate. This means that these nanoparticles are transported by the resonant radiation force much stronger than the gravitational force.

Inner structure of ZnO microspheres fabricated via laser ablation in superfluid helium

“…The fabricated microspheres show a crystalline structure even at the surface and at remarkably low threshold WGM lasing with continuous-wave laser excitation [12]. The laser ablation in superfluid helium can also produce metallic microspheres [13] and semiconductor nanoparticles [14]. An in-depth investigation of the microscopic fabrication mechanism is necessary to open the possibilities of the method targeting the microsphere fabrication with different materials under different conditions [15].…”

Theory of nano optical manipulation by designed light fields under excitonic resonance conditions

“…This value is considerably smaller than the calculated radiative width Γ ξ = 26 μeV for a particle with a radius of 20 nm, respectively. In fact, it has been reported that the effectiveness of RP is demonstrated in the transportation experiment of CuCl nanoparticles of several tens of nm radius in superfluid helium [4]. This environment provides an optimum condition for resonance effects because of its low temperature and low viscosity [14].…”

“…In the previous studies [2,3], we have theoretically clarified the possibilities of resonant nano optical manipulation (NOM), where RF becomes sufficiently strong to manipulate nanoparticles under an optical excitation of an exciton in them, and that RF selectively arises reflecting the quantum characteristics of each nanoparticle depending on its geometric properties such as size, shape and quality. In fact, the recent experiment has indicated the effectiveness of this mechanism in NOM, where CuCl nanoparticles are transported over macroscopic distance by excitonic resonant light [4]. Furthermore, in our fairly recent works [5,6], we have revealed that attractive and repulsive forces can arise under optical excitation of the electromagnetically coupled states of exciton polaritons in spatially separated nanostructures, which will enable us to control the relative motion of nano-objects.…”

Theory of light‐induced force microscopy to observe collective excited states in quantum‐dot‐array

“…This value is considerably smaller than the calculated radiative width (Γ iζ = -Im[A iζ , iζ ]) 13.4 μeV and 26 μeV for a considered QDs with a radius of 16 nm and 20 nm, respectively. In fact, the effectiveness of RP has been experimentally demonstrated in the transportation of CuCl QDs of several tens of nanometers radius in superfluid helium which provides an ideal condition with extremely low temperature and low viscosity [13]. The incident light intensity is assumed to be 50 W/cm 2 , which is within the linear response regime through all calculations.…”