Search results for "Stopband"
showing 5 items of 5 documents
Acousto-optic interaction in biconical tapered fibers: shaping of the stopbands
2016
The effect of a gradual reduction of the fiber diameter on the acousto-optic (AO) interaction is reported. The experimental and theoretical study of the intermodal coupling induced by a flexural acoustic wave in a biconical tapered fiber shows that it is possible to shape the transmission spectrum, for example, substantially broadening the bandwidth of the resonant couplings. The geometry of the taper transitions can be regarded as an extra degree of freedom to design the AO devices. Optical bandwidths above 45 nm are reported in a tapered fiber with a gradual reduction of the fiber down to 70 μm diameter. The effect of including long taper transition is also reported in a double-tapered st…
Tunable defects in colloidal photonic crystals
2006
We present a bottom-up approach for the construction of tunable functional defects in colloidal photonic crystals (CPCs). These structures incorporate polyelectrolyte multilayer (PEM) planar defects embedded in silica CPCs through a combination of evaporation induced self-assembly and microcontact transfer printing. We show how the enormous chemical diversity inherent to PEMs can be harnessed to create chemically active defect structures responsive to solvent vapor pressures, light, temperature as well as redox cycling. A sharp transmission state within the photonic stopband, induced by the PEM defect, can be precisely, reproducibly and in some cases reversibly tuned by these external stimu…
Analysis of Inhomogeneously Dielectric Filled Cavities Coupled to Dielectric-Loaded Waveguides: Application to the Study of NRD-Guide Components
2004
In this paper, we present two contributions. First, we develop a computationally efficient technique for the full-wave characterization of inhomogeneously dielectric-filled cavities connected to inhomogeneously dielectric-loaded waveguides. This method is based on the expansion of the electromagnetic field within the cavity in terms of their solenoidal and irrotational modes. The presented formulation allows the treatment of hybrid modes in the waveguide ports, where the definition of a characteristic modal impedance or admittance is not possible. The multimode scattering matrix of the structure is computed throughout an efficient implementation of the orthonormal-basis method for the calcu…
"Smart" defects in colloidal photonic crystals
2005
AbstractWe present a bottom-up approach for the construction of "Smart" active defects in colloidal photonic crystals (CPCs). These structures incorporate polyelectrolyte multilayer (PEM) planar defects embedded in silica CPCs through a combination of evaporation induced self-assembly and microcontact transfer printing. We show how the enormous chemical diversity inherent to PEMs can be harnessed to create chemically active defect structures responsive to solvent vapor pressures, light, temperature as well as redox cycling. A sharp transmission state within the photonic stopband, induced by the PEM defect, can be precisely, reproducibly and in some cases reversibly tuned by these external s…
Efficient software tool for the analysis of planar-based metamaterial structures
2007
We present a software tool specialized in the analysis of metamaterial structures based on planar circuits. The tool implements a formulation for open transversal multilayered structures, which reduces the number of unknowns employed in the problem. Besides, the formulation has been efficiently accelerated by means of a Kummer-like decomposition, extracting the singular behaviour of the Green's functions from the frequency analysis. By means of this formulation, several different kinds of metamaterial structures built in coplanar and microstrip technologies are successfully analyzed, obtaining bandpass and stopband filter responses in a fast and accurate way. (7 pages)