We show theoretically that a one-dimensional photonic crystal containing a negative-index material has an omnidirectional gap, owing to the mechanism of zero (volume) averaged refractive index. In contrast to the Bragg gap, the edge of such a zero-n̄ gap is insensitive to incident angle and polarization. When an impurity is introduced, a defect mode appears inside the zero-n̄ gap with a very weak dependence on incident angle and invariant with scaling.

The transmission properties of a one-dimensional photonic crystal containing two kinds of single-negative (permittivity- or permeability-negative) media are studied theoretically. We show that this structure can possess a type of photonic gap with zero effective phase (phi(eff) ). The zero-phi(eff) gap distinguishes itself from a Bragg gap in that it is invariant with a change of scale length and is insensitive to thickness fluctuation. In contrast to a photonic gap corresponding to zero averaged refractive index, the zero-phi(eff) gap can be made very wide by varying the ratio of the thicknesses of two media. An equivalent transmission-line model is utilized to explain the properties. A photonic quantum-well structure based on zero-phi(eff) gaps is proposed as a multiple channeled filter that is compact and robust against disorder.

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High-efficiency narrowband emission is always in the central role of organic optoelectronic display applications. However, the development of organic afterglow materials with sufficient color purity and high quantum efficiency for hyperafterglow is still great challenging due to the large structural relaxation and severe non-radiative decay of triplet excitons. Here we demonstrate a simple yet efficient strategy to achieve hyperafterglow emission through sensitizing and stabilizing isolated fluorescence chromophores by integrating multi-resonance fluorescence chromophores into afterglow host in a single-component copolymer. Bright multicolor hyperafterglow with maximum photoluminescent efficiencies of 88.9%, minimum full-width at half-maximums (FWHMs) of 38 nm and ultralong lifetimes of 1.64 s under ambient conditions are achieved. With this facilely designed polymer, a large-area hyperafterglow display panel was fabricated. By virtue of narrow emission band and high luminescent efficiency, the hyperafterglow presents a significant technological advance in developing highly efficient organic afterglow materials and extends the domain to new applications.

In this paper, the electromagnetic (EM) tunneling phenomenon in a sandwich structure consisting of an mu-negative (MNG) medium, air, and an epsilon-negative (ENG) medium is investigated by means of the transfer-matrix method and microwave experiments. Both results demonstrate that by properly choosing parameters, EM waves can efficiently tunnel through a long distance over several hundreds times the length of the device. Unlike in the ENG-MNG slabs, the electric and the magnetic field of the tunneling mode is interestingly separated and localized at the interface of MNG-air and ENG-air, respectively. Therefore, this structure may be important for potential applications in wireless information and energy transmission, for its high efficiency, security, and health.

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We show theoretically that heterostructures consisting of single-negative materials can possess tunneling modes inside forbidden gaps, owing to the resonant coupling of the evanescent-wave-based interface modes. The tunneling modes appear when the heterostructure becomes nihility. They are independent of incident angles and polarizations and have zero phase delay, which can be utilized to design zero-phase-shift omnidirectional filters.