Phonons play a key role in the physical properties of materials, and have long been a topic of study in physics. Nanoscale experimental methods to excite and detect phonons are imperative for their application.

Cavity optomechanical systems make possible the fine manipulation of mechanical degrees of freedom with light, adding functionality and having broad appeal in photonic technologies. We show that distinct mechanical modes can be exploited with a temporally modulated Floquet drive to steer between distinct steady states induced by changes of cavity radiation pressure. We investigate the additional influence of the thermo-optic nonlinearity on these dynamics and find that it can suppress or amplify the control mechanism in contrast to its often performance-limiting character. Our results provide new techniques for the characterization of thermal properties of optomechanical systems and their control, sensing and computational applications.

Nanophononics has the potential for information transfer, in an analogous manner to its photonic and electronic counterparts. The adoption of phononic systems has been limited, due to difficulties associated with the generation, manipulation, and detection of phonons, especially at GHz frequencies. Existing techniques often require piezoelectric materials with an external radiofrequency excitation that are not readily integrated into existing CMOS infrastructures, while nonpiezoelectric demonstrations have been inefficient. In this Letter, we explore the optomechanical generation of coherent phonons in a suspended 2D silicon phononic crystal cavity with a guided mode around 6.8 GHz. By incorporating an air-slot into this cavity, we turn the phononic waveguide into an optomechanical platform that exploits localized photonic modes resulting from inherent fabrication imperfections for the transduction of mechanics. Such a platform exhibits very fine control of phonons using light, and is capable of coherent self-sustained phonon generation around 6.8 GHz, operating at room temperature. The ability to generate high frequency coherent mechanical vibrations within such a simple 2D CMOS-compatible system could be a first step towards the development of sources in phononic circuitry and the coherent manipulation of other solid-state properties.

Chaos and synchronization are important and ubiquitous phenomena in nature. Chaos synchronization spontaneously emerges in the collective dynamics of coupled nonlinear oscillators; however, its control remains a challenge at the nanoscale. Here, we present an experimental and theoretical investigation of synchronization on the route to chaos and in the chaotic regime in mechanically coupled electro-optomechanical nanocavities. In this system an integrated electroactuation enables one to drive the mechanical normal modes in the nonlinear regime while the mechanical displacement is transferred to an optical probe which provides a direct readout access to both their amplitude and phase responses. Using a single low-frequency modulation of the force applied to each normal mode, we induce a chaotic dynamics in the coupled nanoresonators. By applying a simultaneous force modulation on each of the normal modes, we generate chaos at two distinct carrier frequencies referred to as bichromatic chaos. The mode amplitudes are synchronized all the way on the route to chaos as well as in the chaotic regime. Meanwhile, their phases experience complex dynamics with imperfect synchronization in the chaotic regime. These results set the ground for applications of mechanical nanoresonators in areas such as metrology, multispectral chaotic encryption, and analog computing.

Phonons offer the possibility to connect the microwave and optical domains while being efficiently transduced with electronic and optical signals. Here, we present a multimodal optomechanical platform, consisting of a mechanical-optical-mechanical resonator configuration. The mechanical modes, with frequencies at 265 MHz and 6.8 GHz, can be simultaneously excited into a phonon lasing regime as supported by a stability analysis of the system. Both the megahertz and gigahertz modes enter a self-sustained oscillation regime, leading to the intermodulation of two frequency combs in the optical field. We characterize this platform experimentally, demonstrating previously unexplored dynamical regimes. These results suggest the possibility to control multiple mechanical degrees of freedom via a single optical mode, with implications in gigahertz phononic devices, signal processing, and optical comb sensing applications.

Nanoelectro-opto-mechanical systems enable the synergistic coexistence of electrical, mechanical, and optical signals on a chip to realize new functions. Most of the technology platforms proposed for the fabrication of these systems so far are not fully compatible with the mainstream CMOS technology, thus, hindering the mass-scale utilization. We have developed a CMOS technology platform for nanoelectro-opto-mechanical systems that includes piezoelectric interdigitated transducers for electronic driving of mechanical signals and nanocrystalline silicon nanobeams for an enhanced optomechanical interaction. Room-temperature operation of devices at 2 GHz and with peak sensitivity down to 2.6 cavity phonons is demonstrated. Our proof-of-principle technology platform can be integrated and interfaced with silicon photonics, electronics, and MEMS devices and may enable multiple functions for coherent signal processing in the classical and quantum domains.