417 research outputs found
Upper Bound Imposed upon Responsivity of Optical Modulators
We study theoretically the responsivity of optical modulators. For the case
of linear response we find using perturbation theory an upper bound imposed
upon the responsivity. For the case of two mode modulator we find a lower bound
imposed upon the optical path required for achieving full modulation when the
maximum birefringence strength is given
Sensing Dispersive and Dissipative Forces by an Optomechanical Cavity
We experimentally study an optomechanical cavity that is formed between a
mechanical resonator, which serves as a movable mirror, and a stationary
on-fiber dielectric mirror. A significant change in the behavior of the system
is observed when the distance between the fiber's tip and the mechanical
resonator is made smaller than about 1 micrometer. The observed effects are
attributed to the combined influence of Casimir force, Coulomb interaction due
to trapped charges, and optomechanical coupling. The comparison between
experimental results and theory yields a partial agreement
Damping in a Superconducting Mechanical Resonator
We study a mechanical resonator made of aluminum near the normal to super
conductivity phase transition. A sharp drop in the rate of mechanical damping
is observed below the critical temperature. The experimental results are
compared with predictions based on the Bardeen Cooper Schrieffer theory of
superconductivity and a fair agreement is obtained
Electrically tunable collective response in a coupled micromechanical array
We employ optical diffraction to study the mechanical properties of a grating array of suspended doubly clamped beams made of Au. The device allows application of electrostatic coupling between the beams that gives rise to formation of a band of normal modes of vibration (phonons). We parametrically excite these collective modes and study the response by measuring the diffraction signal. The results indicate that nonlinear effects strongly affect the dynamics of the system. Further optimization will allow employing similar systems for real-time mechanical spectrum analysis of electrical waveforms
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