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Register a new userMulti-tip near-field scanning thermal microscopy
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Added by
Philippe Ben-Abdallah
Publication date
2019
fields
Physics
and research's language is
English
Authors
Philippe Ben-Abdallah
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A theory is presented to describe the heat-flux radiated in near-field regime by a set of interacting nanoemitters held at different temperatures in vacuum or above a solid surface. We show that this thermal energy can be focused and even amplified in spots that are much smaller than those obtained with a single thermal source. We also demonstrate the possibility to locally pump heat using specific geometrical configurations. These many body effects pave the way to a multi-tip near-field scanning thermal microscopy which could find broad applications in the fields of nanoscale thermal management, heat-assisted data recording, nanoscale thermal imaging, heat capacity measurements and infrared spectroscopy of nano-objects.
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Scattering-type scanning near-field optical microscopy (s-SNOM) is instrumental in exploring polaritonic behaviors of two-dimensional (2D) materials at the nanoscale. A sharp s-SNOM tip couples momenta into 2D materials through phase matching to excite phonon polaritons, which manifest as nanoscale interference fringes in raster images. However, s-SNOM lacks the ability to detect the progression of near-field property along the perpendicular axis to the surface. Here, we perform near-field analysis of a micro-disk and a reflective edge made of isotopically pure hexagonal boron nitride (h-11BN), by using three-dimensional near-field response cubes obtained by peak force scattering-type near-field optical microscopy (PF-SNOM). Momentum quantization of polaritons from the confinement of the circular structure is revealed in situ. Moreover, tip-sample distance is found to be capable of fine-tuning the momentum of polaritons and modifying the superposition of quantized polaritonic modes. The PF-SNOM-based three-dimensional near-field analysis provides detailed characterization capability with a high spatial resolution to fully map three-dimensional near-fields of nano-photonics and polaritonic structures.
We introduce a point-like scanning single-photon source that operates at room temperature and offers an exceptional photostability (no blinking, no bleaching). This is obtained by grafting in a controlled way a diamond nanocrystal (size around 20 nm) with single nitrogen-vacancy color-center occupancy at the apex of an optical probe. As an application, we image metallic nanostructures in the near-field, thereby achieving a near-field scanning single-photon microscopy working at room temperature on the long term. Our work may be of importance to various emerging fields of nanoscience where an accurate positioning of a quantum emitter is required such as for example quantum plasmonics.
Reduction of the inter-probe distance in multi-probe and double-tip STM down to the nanometer scale has been a longstanding and technically difficult challenge. Recent multi-probe systems have allowed for significant progress by achieving distances of around 30 nm using two individually driven, traditional metal wire tips. For situations where simple alignment and a fixed separation can be advantageous, we here present the fabrication of on-chip double-tip devices that incorporate two mechanically fixed gold tips with a tip separation of only 35 nm. We utilize the excellent mechanical, insulating and dielectric properties of high quality SiN as a base material to realize easy-to-implement, lithographically defined and mechanically stable tips. With their large contact pads and adjustable footprint these novel tips can be easily integrated with most existing commercial combined STM/AFM systems.
Two-dimensional van der Waals (vdW) crystals can sustain various types of polaritons with strong electromagnetic confinements, making them highly attractive for the nanoscale photonic and optoelectronic applications. While extensive experimental and numerical studies are devoted to the polaritons of the vdW crystals, analytical models are sparse. Particularly, applying such a model to describe the polariton behaviors visualized by state-of-art near-field optical microscopy requires further investigation. Herein, we develop an analytical waveguide model to describe the polariton propagations in vdW crystals. The dispersion contours, dispersion relations, and electromagnetic field distributions of different polariton waveguide modes are derived. The model is verified by near-field optical imaging and numerical simulation of phonon polaritons in the {alpha}-MoO3, a typical vdW biaxial crystals. The model can be extended to other types of polaritons in vdW crystals, thus allowing for describing and understanding their localized electromagnetic behaviors analytically.
The finite-difference time-domain (FDTD) method is employed to solve the three dimensional Maxwell equation for the situation of near-field microscopy using a sub-wavelength aperture. Experimental result on unexpected high spatial resolution is reproduced by our computer simulation.
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