Fluorescence inhibition near spherical ENZ nanoparticles: competition between radiative and non-radiative processes.

In this work, we aim to study numerically the emission decay rate of a hybrid system combining a quantum emitter (QE) and an epsilon-near-zero (ENZ) spherical nanoparticle (SNP). Inspired by the peculiar behavior of ENZ materials and their high potential in developing unusual abilities in controlling the emission properties of QE. More specifically the control of fluorescence inhibition, or the amplification of the lifetime of the excited state. This can naturally find applications in quantum information storage for optical quantum memories based on light-atom interaction which naturally benefit from storage time control. We demonstrate that the key process in limiting fluorescence inhibition is the competition between inhibition of fluorescence from the radiative processes and energy dissipation due to the non-radiative channels. Furthermore, we illustrate that this balance can be shifted to optimize inhibition as function of the QE position. The optimization happens via SNP size control, material composition, and λENZ of the SNP. This detailed study introduces and paves the way for new research directions on the manipulation and optimization of QE properties in the vicinity of ENZ materials.

A micro-transducer matrix design for the detection of flexural guided waves.

In this paper, a new approach is proposed for the detection of ultrasonic guided waves using a LiNbO3 single crystal-based micro-transducer matrix. This matrix was designed, manufactured, and then used to detect Lamb and Pochhammer-Chree guided waves in plate- and cylinder-like structures. This study highlights the identification of the first flexural mode F(1,1) in cylinders at low frequencies. A network analyser and a laser Doppler vibrometer (LDV) were used to characterise and study the behaviour of the micro-transducer matrix. An experimental device was designed and used to acquire electrical measurements of the micro-transducer vibrations. Then, an original experimental device was developed to generate a selected flexural guided mode in a solid aluminium cylinder. The emitter comprised two semicircular piezoelectric transducers excited with only one phased signal thanks to the inverse position of polarisation. Finally, the results prove that the flexural mode F(1,1) is selected and generated by the emitter, then detected and identified by the micro-transducer matrix.

Wavelength-scale light concentrator made by direct 3D laser writing of polymer metamaterials.

We report on the realization of functional infrared light concentrators based on a thick layer of air-polymer metamaterial with controlled pore size gradients. The design features an optimum gradient index profile leading to light focusing in the Fresnel zone of the structures for two selected operating wavelength domains near 5.6 and 10.4 µm. The metamaterial which consists in a thick polymer containing air holes with diameters ranging from λ/20 to λ/8 is made using a 3D lithography technique based on the two-photon polymerization of a homemade photopolymer. Infrared imaging of the structures reveals a tight focusing for both structures with a maximum local intensity increase by a factor of 2.5 for a concentrator volume of 1.5 λ3, slightly limited by the residual absorption of the selected polymer. Such porous and flat metamaterial structures offer interesting perspectives to increase infrared detector performance at the pixel level for imaging or sensing applications.