Optically tunable dynamics of nano-mechanica systems

• Applicant: Professor Dr. Khaled Karrai
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2004 to 2008
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5421333

The size, the shape and the choice of materials determine the dynamics of a nanomechanical resonator such as its resonance frequencies and quality factor. However once fabricated, the nano-device's mechanical properties are hardly tunable. In micron sized systems we have demonstrated that this is no longer the case when the device is coupled to an optical resonator such as a Fabry-Perot cavity through light induced forces. For instance we measured that the resonator's rigidity is continuously addressable simply through the photon power stored in the optical oscillator. We anticipate that not only the frequency of the mechanical resonance can be broadly tuned but also its quality factor can be optically increased to very large values, in which case, it would be possible to drive the device in self-oscillations just by shining light at it. Conversely, we expect that it is also possible to reduce the resonator's mechanical quality factor to a point where optical cooling can be achieved, possibly down to the quantum mechanical limit. Understanding quantitatively how optical fields allow pumping and probing the mechanical excitations of a nanoresonator, allows not only numerous applications but also investigating the physics of energy dissipation limiting nano-mechanical systems; a physics that is yet not understood.

• DFG Programme: Research Grants
• Participating Person: Dr. Heribert Lorenz