| Popis: |
This Thesis reports on the study of hybrid nano-optomechanical metamaterials, and their sensing, nonlinear and switching functionalities.I have constructed a dedicated apparatus for optical measurements of photonic metamaterials in vacuum during acoustic excitation. It is based on a fiberized inverted microscope setup operating at the wavelength of 1310 nm in both reflection and transmission modes.I have provided the first observation of fluctuations of optical properties of metamaterials due to thermal motion. In a plasmonic nanomechanical metamaterial thermal motion of mechanical components with an amplitude of a few hundreds of picometers leads to reflectivity fluctuations of the order of 0.1%. I have demonstrated the first tuning of mechanical eigenfrequencies of plasmonic nanomechanical metamaterials with light. Controlling the internal stress of the structure via light illumination allows tuning of the mechanical frequencies at which it can be efficiently driven. Eigenfrequency shifts of up to 19.5 % are measured for 7 μW of incident optical power. I have developed the first nanomechanical, metamaterial-based nanobolometer. Non-contact optical detection of infrared radiation is based on the detection of light scattered by two optically coupled nanomechanical beams providing spatial resolution of 400 nm, eigenfrequency shift per unit of incident optical power (responsivity) of 2-3%/μW with a noise equivalent power of 3-5 nW/Hz1/2. I have demonstrated a new type of volatile optical bistability in a resonant hybrid nanooptomechanical device. The bistable function has been demonstrated on a pair of anchored beams decorated with plasmonic metamolecules. The nonlinearity resides in the mechanical properties of the beams that can be driven to a bistable response by acoustic signals modulated at their natural mechanical resonances. Optical switching between the two mechanically stable states is demonstrated with 6 μW of incident optical power and the bistable states are sustained and controllable by about a pW of mechanical power delivered to a beam. Overall, hybridization of mechanically and optically resonant structures can provide sensing and switching functionalities based on their mechanical properties and nonlinear response. |
