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(a) Model of optical microcavity formed between two thin films of gold. The enhanced electric fields (E i;cav, E r;cav) exert CIRF on the cantilever; integer subscripts to electric field labels indicate the numbers of layers. Displacing the cantilever from its resonance position generates a restoring force opposing the radiation force. (b) Dependence of the effective mechanical frequency (upper panel) and the reflection (lower panel) on cavity length normalized with respect to the wavelength λ of incident light. (c) CIRF as a periodic function of cavity length with optical rigidity K opt for 1 mW input power, as measured in Ref. 4 . λ is set to 632.8 nm taking as incident light a HeNe laser beam.
(a) Equilibrium position x equi of the cantilever for various initial positions: from 0.985 to 0.97λ (solid black to dashed aqua line); the black region presents the unstable regime, where the total rigidity K is negative. (b) Effective temperature T eff versus input power. High peaks appear when the effective mechanical frequency ω of the cantilever equals the frequency of non-optical driving force Ω, and low dips correspond to maximum in |K opt| turning the cantilever dynamics to a far off-resonance driven regime, where ω is much smaller than Ω.
Input power dependence of T eff for a random driving force with various time steps Δ, Δ/4, and Δ/20 starting from the same initial position indicated by the solid red line in Fig. 2 . T eff for high input powers show an asymptotical trend indicating the stability even under different collision times. The dashed-dotted aqua line presents the equilibrium position scaled along the right-side axis.
Frequency shift and higher-mode appearance for various time steps. (a) and (b) Mechanical frequency dependence of intensity with slow collisions with Δ and Δ/4, respectively, showing only the frequency shift by increasing CIRF. (c) Mechanical frequency dependence of intensity for the fast collisions with Δ/20, where modes corresponding to 2ω eff clearly appear.
Parameters for thin films.
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