Compact Optical components sensitive to incident wave-vector direction are essential in image-processing, wavefront-manipulation, and metrology such as LIDAR. Here we demonstrate a new class of metasurfaces which exhibit optical spectral features strongly correlated with incident illumination angle. The spectra of such metasurfaces feature sharp transmission dips centred around 800 nm when illuminated at oblique incidence, where the strength of the dip increases as incident angle increases remaining tightly confined within a 100 nm band. The metasurfaces are capable of accepting large incident angles (>30°) without the appearance of higher-order diffraction modes, while displaying dramatic transmission decreases (~80% reduction).
Strongly coupled organic microcavities are up-and-coming material systems for ambient polaritonics. A broad range of suitable materials made possible the experimental observation of polariton lasing across the whole visible range, as well as device-concepts ranging from ultra-fast transistors and all-optical logic gates to single-photon switching, all at room temperature under ambient conditions. Unlike the case of inorganic semiconductor microcavities, where continuous-wave excitation allows for the replenishment of particle losses, leading to the realization of steady-state polariton condensates, in organic semiconductors photobleaching and polaron formation prevent CW operation. BODIPY dyes have been the subject of thorough studies for their applications in the strong coupling regime. Strongly coupled BODIPY microcavities and polariton lasing in these structures allow for highly monochromatic tunable coherent emission of duration up to ~two picoseconds. Here, we use a single-mode lambda/2 strongly coupled microcavity of a BODIPY dye molecule, employ a single-shot dispersion imaging technique to study polariton lasing in a planar organic microcavity, and achieve a quasi-steady state exciton-polariton condensation under single-shot excitation in such systems. Temporal dynamics of a single-shot exciton-polariton lasing is of particular interest and importance for understanding rates of depletion and replenishment of the exciton reservoir and polariton states, respectively, under pulsed excitation. Moreover, the direct measurement of the condensate lifetime provides valuable insight into the transient processes of nonequilibrium polariton condensation. Long-lasting condensates exceeding polariton lifetime for several orders of magnitude push the system one step closer towards the regime of dynamic equilibrium and could be a missing puzzle towards polariton applications such as connected polariton devices and condensate lattices implemented at ambient conditions, opening the possibility for all-optical polariton circuitry on a chip.
We report on a discovery that homogeneous metallic non-diffracting metasurfaces of a certain type allow robust speckle-free discrimination between different degrees of the spatial coherence of light. The effect has no direct analogue in natural materials and has been previously unseen in metamaterials (and metasurfaces in particular). It results in a qualitative change of the optical response of metasurfaces, whereby their transmission (and reflection) spectra acquires different spectral components, depending on whether the nano-structures are illuminated with spatially coherent or incoherent light. This effect is robust and exceptionally strong (e.g., the resulting absolute change in transmission exceeds 50%), which makes it immediately suitable for practical applications, such as optical metrology, imaging and communications. Among the metasurfaces that have been found to exhibit the new effect are planar metamaterials featuring a continuous periodic zigzag pattern. The reported samples were designed to operate in the near-IR part of the spectrum and composed of arrays of continuous zigzag nano-wires, as well as their inversion, i.e., continuous zigzag nano-slits, covering the area of ~20x20mkm2. The measured data suggest that these apparently trivial metasurfaces, while non-diffracting, can indeed behave differently under spatially incoherent and coherent illumination. The systematic experimental investigation and rigorous theoretical analysis of this phenomenon (the results of which will be presented at the conference) reveal that the effect is underpinned by strongly non-local response of the metasurfaces. Its mechanism involves interference of light scattered via non-dispersive delocalised plasmon modes uniquely supported by the fabric of the metasurfaces.
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