No abstract

The polarization controlled optical signal routing has many important applications in photonics such as polarization beam splitter. By using two-dimensional transmission lines with lumped elements, we experimentally demonstrate the selective excitation of guided modes in waveguides composed of two kinds of single-negative metamaterials. A localized, circularly polarized emitter placed near the interface of the two kinds of single-negative metamaterials only couples with one guided mode with a specific propagating direction determined by the polarization handedness of the source. Moreover, this optical spin-orbit locking phenomenon, also called the photonic spin Hall effect, is robust against interface fluctuations, which may be very useful in the manipulation of electromagnetic signals.

We propose a topological description for gaps of one-dimensional symmetric all-dielectric photonic crystals (PCs). It is shown that, in the propagating direction, the effective electromagnetic parameters of PCs can be derived from one unit cell with mirror symmetry. Besides, at the frequencies of gaps, these symmetric PCs can be described as photonic insulators with effective negative permittivity or negative permeability. Moreover, based on the mapping of Maxwell's equations to the Dirac equation and the band inversion achieved by tuning the material and structural parameters, we demonstrate that the gaps of PCs with effective negative permittivity or negative permeability possess different topological orders. Lastly, we show that a bound state is robust against the disorder under a zero-average-effective-mass condition in a heterostructure made of two PCs with different topological orders.

We propose a scheme for subwavelength electromagnetic diode by employing the nonreciprocal electromagnetically induced transparency (EIT) in metamaterials. One-way response, with 17.36 dB transmission contrast and −4.4 dBm operating power, is conceptually demonstrated in a microwave waveguide system with asymmetric absorption and a varactor as the nonlinear medium inclusion. Such low-threshold and high-contrast transmission diode action comes from the EIT mechanism, which possesses narrower and sharper features than the Lorentz resonance. This mechanism will be useful for all-optical signal processing with advanced materials.

We theoretically investigate the feasibility of constructing compact and highly efficient all-optical diodes (AODs) based on light tunneling mechanism in heterostructures. Due to light tunneling behaviors in heterostructures with one-dimensional photonic crystals (1D PC) and lossy metallic film, not only very large nonlinear permittivity of metal can be utilized sufficiently but also the structures with strongly nonreciprocal electric field distributions can be constructed. Finally we design a composite structure consisting of 1D PC-metal heterostructures to achieve the optimal unidirectional light transmission with 0.984 transmission contrasts, 42% transmission and 0.93 GW/cm(2) operating light power at working wavelength 557.2nm.