Optics and Photonics Society of Iran

Optical tweezers are able to measure femto- and pico- Newton range forces, and have become a powerful tools for different applications e.g. biology, nanotechnology, and microfluidic research. Transferring of angular momentum from laser beam to a trapped particle causes it to rotate. Here, we report on rotation of metallic nanoparticles in trap and to best of our knowledge, rotation of silver nanocubes as a first time. Rotation speed measurement has done by power spectrum and autocorrelation analysis of signal acquired by quadrant photodiode which is commonly used to measure the trapping stiffness. Our experiments show a rotation speed about 100 Hz and 10 kHz for a 400 nm gold sphere and 100 nm silver cube, respectively.