Cavity-enhanced emission from a dye-coated microsphere.

We have observed whispering gallery modes in the inelastic emission from a 9.8 microm polystyrene bead coated with a monolayer of AlexaFluor 488 dye. Using a separate near-IR trapping laser and an Ar+ excitation laser enables us to isolate and study a single dye-coated bead in a colloidal suspension without causing any bead damage.

Large capture-range of a single-beam gradient optical trap.

We have observed long-range trapping with a single-beam gradient force optical trap. 6 to 10 microm polystyrene beads that are initially approximately 100 microm away from the trap-center can be pulled into the trap-center. Particle-tracking enables us to determine the trajectory of a bead as it moves towards the trap-center and map out a capture zone inside which trapping can occur.