Full text loading...
Assembly of multi-walled carbon nanotube enhanced optical nanotweezers. (a) A schematic of a plasmonically active carbon nanotube immobilized on a silicon waveguide. ((b)–(e)) The orientation and assembly of a carbon nanotube onto the waveguide by optical gradient forces. (f) An SEM micrograph of an assembled trap.
FDTD simulation of the CNT nanotweezers. (a) Electric field strength around a 1.5 μm nanotube atop a silicon waveguide at 1550 nm. (b) The predicted electric intensity along the major axis of the nanotube within the resonant evanescent field. (c) The intensity gradient along the major axis of the nanotube. The intensity gradient, proportional to the attractive optical force on a polarizable particle, is maximum just outside the two ends of the nanotube.
Optical trapping with the CNT nanotweezers. (a) Low power optical trapping. (i) Carbon nanotubes are immobilized onto the waveguide, and 520 nm polystyrene bead solution is flowed in. ((ii)–(iv)) When the laser is on at low power, the beads are attracted to the ends of the nanotubes and stably trapped on both sides of the waveguide. (v) When the laser is switched off, the beads are freed from the trap and diffuse back into solution. (b) High power optical trapping. ((i)–(iii)) At high power, the beads surround the whole CNT surface ((iv) and (v)) Even when the laser is switched off, the innermost beads stay irreversibly bound to the surface.
Binding of 100 nm silver beads to different carbon nanotube trap geometries. (a) For a single MWCNT, two silver beads bind near the end of the rod. ((b)–(d)) For more complicated multiple-CNT geometries, silver beads are found to bind both at the ends of the rods, and also at the intersection points between two or more rods.
Article metrics loading...