We demonstrate optical nonlinearities due to the interaction of weak optical fields with the collective motion of a strongly dispersive ultracold gas. The combination of a recoil-induced resonance in the high gain regime and optical waveguiding within the dispersive medium enables us to achieve a collective atomic cooperativity of 275+/-50 even in the absence of a cavity. As a result, we observe optical bistability at input powers as low as 20 pW. The present scheme allows for dynamic optical control of the dispersive properties of the ultracold gas using very weak pulses of light. The experimental observations are in good agreement with a theoretical model.
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http://dx.doi.org/10.1103/PhysRevLett.101.063901 | DOI Listing |
We designed silicon nanowire array cavities with high optical confinement (Γ) in the central nanowire and a high quality factor () through an inverse design method that maximizes Γ×. Moreover, we fabricated an inversely designed cavity with inline input and output waveguides, which is a new configuration for such cavities. The experimental exceeded 50,000, which was consistent with a simulation.
View Article and Find Full Text PDFChem Sci
January 2025
Department of Chemical Engineering and Chemistry, Institute for Complex Molecular Systems, Eindhoven University of Technology 5600 MB Eindhoven The Netherlands
Using photoswitchable molecules to manipulate supramolecular interactions under light illumination has driven advancements in numerous fields, allowing for the strategic alteration of molecular systems. However, integrating the moiety responsible for these interactions into the photochromic scaffold can be complex and may hamper the switching efficiency. We thus explored a simple class of organic molecules, namely thiosemicarbazones, featuring both a photoisomerizable C[double bond, length as m-dash]N double bond and a thiourea moiety capable of hydrogen bonding.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Organic Chemistry, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, Bratislava SK-842 15, Slovakia.
The development of new photochromic systems is motivated by the possibility of controlling the properties and functions of materials with high spatial and temporal resolution in a reversible manner. While there are several classes of photoswitches operating in solution, the design of systems efficiently operating in the solid state remains highly challenging, mainly due to limitations related to confinement effects. Triaryl-hydrazones represent a relatively new subclass of bistable hydrazone photoswitches exhibiting efficient / photochromism in solution.
View Article and Find Full Text PDFPhys Rev E
November 2024
William H. Miller III Department of Physics and Astronomy, Johns Hopkins University, Baltimore 21218, USA.
Composite materials made of polymers and liquid crystals have been widely employed in smart windows, optical filters, and bistable displays. However, it is often difficult to decipher the role of the polymer network architecture on the alignment and the texture of liquid crystals. In this study, we use a simple model system where a small amount of polymerizable liquid crystalline monomer is mixed in a liquid crystal that exhibits both a smectic phase and a cholesteric phase with a large helical pitch.
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