Nanoscale Torsional Optomechanics
  Optomechanical transduction is demonstrated for nanoscale torsional resonators evanescently coupled to optical microdisk whispering gallery mode resonators. The on-chip, integrated devices are measured using a fully fiber-based system, including a tapered and dimpled optical fiber probe. With a thermomechanically calibrated optomechanical noise floor down to 7 fm/sqrt(Hz), these devices open the door for a wide range of physical measurements involving extremely small torques, as little as 4x10^-20 N*m. 
P.H. Kim, C. Doolin, B.D. Hauer, A.J.R. MacDonald, M.R. Freeman, P.E.   Barclay and J.P. Davis
cond-mat.mes-hall physics.optics