TY - JOUR
T1 - Optical forces and torques in nonuniform beams of light
AU - Ruffner, David B.
AU - Grier, David G.
PY - 2012/4/24
Y1 - 2012/4/24
N2 - The spin angular momentum in an elliptically polarized beam of light plays several noteworthy roles in optical traps. It contributes to the linear momentum density in a nonuniform beam, and thus to the radiation pressure exerted on illuminated objects. It can be converted into orbital angular momentum, and thus can exert torques even on optically isotropic objects. Its curl, moreover, contributes to both forces and torques without spin-to-orbit conversion. We demonstrate these effects experimentally by tracking colloidal spheres diffusing in elliptically polarized optical tweezers. Clusters of spheres circulate deterministically about the beam's axis. A single sphere, by contrast, undergoes stochastic Brownian vortex circulation that maps out the optical force field.
AB - The spin angular momentum in an elliptically polarized beam of light plays several noteworthy roles in optical traps. It contributes to the linear momentum density in a nonuniform beam, and thus to the radiation pressure exerted on illuminated objects. It can be converted into orbital angular momentum, and thus can exert torques even on optically isotropic objects. Its curl, moreover, contributes to both forces and torques without spin-to-orbit conversion. We demonstrate these effects experimentally by tracking colloidal spheres diffusing in elliptically polarized optical tweezers. Clusters of spheres circulate deterministically about the beam's axis. A single sphere, by contrast, undergoes stochastic Brownian vortex circulation that maps out the optical force field.
UR - http://www.scopus.com/inward/record.url?scp=84860300478&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84860300478&partnerID=8YFLogxK
U2 - 10.1103/PhysRevLett.108.173602
DO - 10.1103/PhysRevLett.108.173602
M3 - Article
AN - SCOPUS:84860300478
SN - 0031-9007
VL - 108
JO - Physical Review Letters
JF - Physical Review Letters
IS - 17
M1 - 173602
ER -