Author: nanooptomechanics

Optically levitated multiple nanoparticles have emerged as a platform for studying complex fundamental physics such as non-equilibrium phenomena, quantum entanglement, and light-matter interaction, which could be applied for sensing weak forces and torques with high sensitivity and accuracy. An optical trapping landscape of increased complexity is needed to engineer the interaction between levitated particles beyond the single harmonic trap. However, existing platforms based on spatial light modulators for studying interactions between levitated particles suffered from low efficiency, instability at focal points, the complexity of optical systems, and the scalability for sensing applications. Here, we experimentally demonstrated that a metasurface that forms two diffraction-limited focal points with a high numerical aperture (∼0.9) and high efficiency (31 %) can generate tunable optical potential wells without any intensity fluctuations. A bistable potential and double potential wells were observed in the experiment by varying the focal points’ distance, and two nanoparticles were levitated in double potential wells for hours, which could be used for investigating the levitated particles’ nonlinear dynamics, thermal dynamics, and optical binding. This would pave the way for scaling the number of levitated optomechanical devices or realizing paralleled levitated sensors.

Ref:
Tunable on-chip optical traps for levitating particles based on single-layer metasurface
C. Sun, H. Pi, K. S. Kiang, T. S. Georgescu, J. Y. Ou*, H. Ulbricht, J. Yan*
Nanophotonics (2024) published online DoI:10.1515/nanoph-2023-0873

 

 

Despite recent tremendous progress in optical imaging and metrology, there remains a substantial resolution gap between atomic-scale transmission electron microscopy and optical techniques. Is optical imaging and metrology of nanostructures exhibiting Brownian motion possible with such resolution, beyond thermal fluctuations? Here we report on an experiment in which the average position of a nanowire with a thermal oscillation amplitude of ∼150 pm is resolved in single-shot measurements with subatomic precision of 92 pm, using light at a wavelength of λ = 488 nm, providing an example of such sub-Brownian metrology with ∼λ/5,300 precision. To localize the nanowire, we employ a deep-learning analysis of the scattering of topologically structured light, which is highly sensitive to the nanowire’s position. This non-invasive metrology with absolute errors down to a fraction of the typical size of an atom, opens a range of opportunities to study picometre-scale phenomena with light.

Picophotonic localization metrology beyond thermal fluctuations
T. Liu,C-H.Chi, J. Y. Ou,J.Xu,E.A. Chan,K. F. MacDonald and N. I. Zheludev
Nat. Mater. (2023) doi: 10.1038/s41563-023-01543-y

Time crystals are an eagerly sought phase of matter with broken time-translation symmetry. Quantum time crystals with discretely broken time-translation symmetry have been demonstrated in trapped ions, atoms and spins whereas continuously broken time-translation symmetry has been observed in an atomic condensate inside an optical cavity. Here we report that a classical metamaterial nanostructure, a two-dimensional array of plasmonic metamolecules supported on flexible nanowires, can be driven to a state possessing all of the key features of a continuous time crystal: continuous coherent illumination by light resonant with the metamolecules’ plasmonic mode triggers a spontaneous phase transition to a superradiant-like state of transmissivity oscillations, resulting from many-body interactions among the metamolecules, characterized by long-range order in space and time. The phenomenon is of interest to the study of dynamic classical many-body states in the strongly correlated regime and applications in all-optical modulation, frequency conversion and timing.

Photonic metamaterial analogue of a continuous time crystal
T. Liu, J. Y. Ou, K. F. MacDonald, and N. I. Zheludev
Nat. Phys. (2023) doi: 10.1038/s41567-023-02023-5 [Press coverage]

Nanoscale objects move fast and oscillate billions of times per second. Such movements occur naturally in the form of thermal (Brownian) motion while stimulated movements underpin the functionality of nano-mechanical sensors and active nano-(electro/opto) mechanical devices. Here we introduce a methodology for detecting such movements, based on the spectral analysis of secondary electron emission from moving nanostructures, that is sensitive to displace- ments of sub-atomic amplitude. We demonstrate the detection of nanowire Brownian oscillations of ~10 pm amplitude and hyper- spectral mapping of stimulated oscillations of setae on the body of a common flea. The technique opens a range of opportunities for the study of dynamic processes in materials science, nanotechnology and biology.

Detection of sub-atomic movement in nanostructures
T. Liu, J. Y. Ou*, K. F. MacDonald, and N. I. Zheludev
Nanoscale Advances (2021) doi: 10.1039/d0na01068e – pdf

The UK’s Engineering and Physical Sciences Research Council (EPSRC) has announced funding for a five-year research programme, from Feb. 2021, on NEXT GENERATION METROLOGY DRIVEN BY NANOPHOTONICS. This collaboration between the University of Southampton’s Zepler Institute for Photonics & Nanoelectronics and the University of Huddersfield’s Centre for Precision Technologies will harness the latest advances in nanophotonics, plasmonics and metamaterials research to develop optical metrology tools and measurement techniques that can be deployed in the real-world and novel metrology concepts for nanotechnology. 
Work at Southampton will be led by Prof Nikolay Zheludev, Prof Kevin MacDonald, Dr Eric Plum and Dr Jun-Yu(Bruce) Ou. The Programme is supported by project partners including major metrology instrumentation companies Taylor Hobson and Renishaw, as well as QinetiQ, Qioptiq, and academic partners at Nanyang Technological University, Singapore.

Press coverage:

• £5.5M project targets optical measurement systems to power ‘smart factories’
• Emerging industries metrology at the crossroads of photonics and nanotechnology