Electroluminescence in mid-IR of hBN-encapsulated graphene under large bias was recently put into evidence through spectroscopy and noise thermometry. We demonstrate in this presentation that hyperbolic phonon polariton electroluminescence is responsible for efficient out-of-plane energy transfer through hBN. We then show that this energy transfer can be engineered using hBN with various turbidity, exhibiting for the first time that far-field energy transfer in turbid media remains valid in the case of energy transfer by confined hyperbolic rays.
Infrared photodetection at ambient temperature is a challenge that classical photodetectors have not been able to fulfill yet. New materials, like the 2D materials family, and plasmonic nanostructures, are currently explored to address this challenge. We will show how the combination of carefully design coupled Fabry-Perot nanoresonnators and graphene can be used has an ambient infrared photodetector.
Effective cross-sections of nano-objects are fundamental properties that determine their ability to interact with light. However, measuring cross-sections for individual resonators directly and quantitatively remains challenging, particularly because of the very low signals involved. In this contribution, we present how we experimentally measured the thermal emission cross-section of metal-insulator-metal nano-resonators using a hyperuniform distribution based on a hierarchical Poisson-disk algorithm. This method relies on the specific properties of hyperuniform distributions, which ensure that no short-range or long-range correlations between resonators disturb the measured signal.
In this work, we investigate the fabrication and the application of ultra-thin terahertz metasurfaces as thermal converters for indirect terahertz imaging. The microstructures fabricated by an ultrasonically driven printing process (Microplotter) are used to improve the THz to IR conversion efficiency and tune the spectral or polarisation selectivity. The resulting conversion membranes show optical and thermal responses which are consistent with numerical simulations establishing reliable rules to design such membrane at various wavelengths. This work paves the way for a low-cost solution of multispectral terahertz imaging with a standard infrared camera.
Two-photon absorption (TPA) is a third order non-linear process that relies on the quasi-simultaneous absorption of two photons. Therefore, it has been proved to be an interesting tool to measure ultra-fast correlations1 or to design all-optical switches.2 Yet, due to the intrinsically low efficiency of the non-linear processes, these applications rest upon high peak power light sources such as femtosecond and picosecond pulsed laser. However TPA has also been noticed as an appealing new scheme for quantum infrared detection.3, 4 Indeed, typical quantum detection of IR radiation is based on small gap semiconductors that need to be cooled down to cryogenic temperature to achieve sufficient detectivity. TPA enables the absorption of IR photons by wide gap semiconductors when pump photons are provided to complete optical transitions across the gap. Still, the low efficiency of TPA represents a difficulty to detect usual infrared photon fluxes. To tackle this issue, we combined three strategies to improve the detection efficiency. First, it has been proved theoretically and experimentally that using different pump and signal photon energies, which is known as non degenerate TPA (NDTPA), help increasing the TPA efficiency by several orders of magnitude.5 Secondly, it is well known that TPA has a quadratic dependence with the signal electric fields modulus, so we designed a specific nanostructure to enhance the signal field inside the active medium of the detector. Finally, since TPA is a local quasi-instantaneous process, both pump and signal photons must be temporarily and spatially co-localized inside the active medium. We made sure to maximize the overlap of the fields inside our device. In this proceeding, we report the concepts of nanostructures and how it influences TPA absorption in a PIN photodiode. Experimental data point out that infrared photons were detected inside our first generation of diodes. However some issues are still to deal with to reach infrared detection with low fluxes thermal sources. The SNR (signal to noise ratio) can be widely improved by reaching higher values of NDTPA photocurrent and limiting the sub-gap absorptions mainly responsible for the structure noise. Consequently a second generation of nanostructured photodiodes has been designed to perform better detection.
Two-photon absorption (TPA) is a third order non-linear process that relies on the quasi-simultaneous absorption of two photons. Therefore, it has been proved to be an interesting tool to measure ultra-fast correlations1 or to design all-optical switches.2 Yet, due to the intrinsically low efficiency of the non-linear processes, these applications rest upon high peak power light sources such as femtosecond and picosecond pulsed laser. However TPA has also been noticed as an appealing new scheme for quantum infrared detection.3, 4 Indeed, typical quantum detection of IR radiation is based on small gap semiconductors that need to be cooled down to cryogenic temperature to achieve sufficient detectivity. TPA enables the absorption of IR photons by wide gap semiconductors when pump photons are provided to complete optical transitions across the gap. Still, the low efficiency of TPA represents a difficulty to detect usual infrared photon fluxes. To tackle this issue, we combined three strategies to improve the detection efficiency. First, it has been proved theoretically and experimentally that using different pump and signal photon energies which is known as non degenerate TPA (NDTPA) help increasing the TPA efficiency by several orders of magnitude.5 Thus we decided to work with different pump and signal wavelength. Secondly, since TPA is a local quasi-instantaneous process, both pump and signal photons must be temporarily and spatially co-localized inside the active medium. We made sure to maximize the overlap of the fields inside our device. Finally, it is well known that TPA has a quadratic dependence with the signal electric fields modulus, so we designed a specific nanostructure to enhance the signal field inside the active medium of the detector.
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