A new asymmetrical diarylethene containing a 1H-imidazo [4,5-f][1,10] phenanthroline unit was synthesized. The compound showed typical photochromism and functioned as a notable fluorescence switch upon alternating irradiation with ultraviolet (UV) and visible light. Its closed-ring isomer could be used as a selective 'naked-eye' colorimetric sensor for Cu(2+), accompanied by a notable color change from blue to colorless. Furthermore, the compound was found to be selective towards Ca(2+), Mg(2+), and Sr(2+) with significant fluorescence changes. On the basis of this characteristic, a logic circuit was constructed by utilizing both light and chemical stimuli as inputs and fluorescence intensity at 487 nm as output.

A novel unsymmetrical diarylethene with an imidazo [4,5‐f] [1,10] phenanthroline unit has been synthesized, and its properties including photochromism and fluorescence have been investigated. It showed favorable photochromism and functioned as notable fluorescence switches by photoirradiation in both solution and a poly (methylmethacrylate) film. Moreover, the interaction between the phenanthroline unit of its closed‐ring isomer with trifluoroacetic acid caused a notable change in its absorption, accompanied by an evident color change from magenta to slateblue. Its fluorescence could be modulated by trifluoroacetic acid and triethylamine. By adding enough amount of trifluoroacetic acid in chloroform, its emission peak hypochromatic shifted from 501 nm to 456 nm, and the intensity increased significantly with a concomitant change of color from bright cyan to bright blue. However, its emission intensity decreased notably by 95% with a fluorescence color change from bright cyan to dark gray by the addition of triethylamine. Copyright © 2013 John Wiley & Sons, Ltd.

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Based on the theory of surface plasmon polaritons (SPPs), a metal–insulator–metal (MIM) waveguide structure consisting of a streamlined resonant cavity and a baffle is proposed. When the incident light waves enter into the waveguide structure, through the interaction between the three discrete states and the continuous state by the streamlined cavity and the baffle, three sharp asymmetric Fano resonance spectra can be formed. The transmission spectrum characteristics of the structure are simulated and analyzed by the finite element method (FEM), and the effects of structure parameters and refractive index on the transmission spectra characteristics are studied. By optimizing the structure parameters, it is found that the performance of the system can be adjusted and optimized flexibly by changing the structure parameters, the figure of merit (FOM) can reach 1.99 × 106, and the sensitivity is 2960 nm/RIU. This flexible Fano resonant-structure has several applications in micro-nano biosensor, nonlinear optics, and slow light devices.

A voltage tunable filter based on a combined metal-insulator-metal nano-cavity waveguide of organic electro-optical material DAST is proposed by using the side-coupled method. The structure of this kind of filter consists of two Y-type cavities and a rectangular waveguide. The transmission spectra, the resonance wavelength, and the magnetic field distribution of the asymmetric Y-type cavity waveguide metal-insulator-metal structure filter has been calculated and analyzed by the finite element numerical simulation method. The results show that this filter has the features of a smooth transmission spectra, a flat passband with the maximum transmission of 0.97, a stopband with the minimum transmission of 0.001, and a wide bandwidth (full width at half maxima achieved 970 nm). The characteristics of the structure filter can be adjusted not only by changing the structural parameters, but also by applying a control voltage. Thus, the adjustability of the filter is increased, and the filter can realize the filtering function of channel selection of the three optical communication windows at the telecommunication regime. There will be great application prospect for this filter structure in high-density integrated circuits and nano-optics.