Benjamin Zwickl

Abstract: It has been over 100 years since the first conclusive demonstration of radiation pressure by Lebedev and Nichols and Hull. Cavity optomechanical systems—high finesse optical cavities coupled to mechanical resonators—are good testing grounds for the mechanical properties of light. The system described in this dissertation is a 7 mm long cavity coupled to a 1 mm square, 50 nm thick silicon nitride membrane. Like many similar optomechanical systems, ranging from LIGO to microtoroids, this work has moved beyond detecting the steady state force of light on a mirror to a rich array of dynamical effects. Classical effects include shifts in the mechanical resonant frequency and optical damping, both of which are demonstrated in this thesis. The (relatively) strong coupling between the light and mechanical resonator can, in principle, demonstrate effects beyond classical mechanics and classical light. This thesis represents an attempt to directly measure random quantum fluctuations in the force of light reflecting from a surface, an effect we call the radiation pressure shot noise. A correlation measurement scheme developed theoretically by Børkje et al. (Borkje2010) was implemented. The scheme is capable of distinguishing the effects of the random thermal force from the random radiation pressure shot noise. Successful suppression of thermal effects was demonstrated, though unfortunately not to the level required to measure the radiation pressure shot noise. In spite of not accomplishing this major physics goal, much was learned about this measurement scheme and its potential for future measurements of the radiation pressure shot noise.