Design of guided mode resonant filters for authentication applications through azimuthal angles varying

Guided mode resonant filters （GMRFs） for authentication application with low sideband reflection at 0^o and 90^o azimuthal angles were designed. Using rigorous coupled-wave analysis, the diffractive characteristics of this kind device with different illumination angles, groove depths, and thicknesses of cover SiO2 layer were investigated. The structure of GMRF which satisfies the requirements for authentication applications was obtained. Illuminated at 30^o for a definite polarization mode, the filter presents symmetrical reflectance shape, low sideband reflectance, two separate reflectance peaks, and definite full-width at halfmaximum （FWHM） at 0^o and 90^o azimuthal angles.

Simplified mode analysis of guided mode resonance gratings with asymmetric coatings

A simplified modal method to explain the resonance phenomenon in guided mode resonance （GMR） grat- ings with asymmetric coatings is presented. The resonance observed is due to the interaction of two propagation modes inside the grating. The reflectivity spectra and electric field distributions calculated from the simplified modal method are compared using rigorous coupled-wave analysis （RCWA）. The in- fluences of high-order evanescent modes on the resonance peak are analyzed. A matrix Fabry-Perot （FP） resonance condition is developed to evaluate the resonance wavelength. An explanation for the resonance phenomenon observed based on the FP resonance phase condition is also proposed and demonstrated. The simplified method provides clear physical insights into CMR gratings that are useful for the analysis of a variety of other resonance gratings.

Photonic crystal waveguides and their applications Invited Paper

Two-dimensional （2D） slab photonic crystal waveguides （PCWGs） on silicon-on-insulator （SOI） wafer were designed and fabricated. Full photonic band gap, band gap guided mode, and index guided mode were observed by measuring the transmission spectra. Mini-stop-bands in the PCWG were simulated with different structure parameters. Coupling characteristics of PCWG were investigated theoretically considering the imperfections during the fabrication process. It was found that suppressing power reservation effect can realize both short coupling length and high coupling efficiency.

Guided modes in the chiral negative refractive index fiber

The novel characteristics of guided modes in the chiral negative refractive index fiber are investigated theoretically in this letter.We derive the characteristic equation of guided modes.Based on two types of chiral metamaterial parameters,we present the dispersion curves,energy flux,and power of guided modes.Some abnormal features,such as the existence of surface mode and dispersion curves with different shapes,intersection of dispersion curves of different guided modes,negative energy flux in the achiral cladding,and zero power at some normalized frequencies,are found in the chiral negative refractive index fiber.

A novel biosensor with enhanced sensitivity based on grating coupled double-layered porous silicon waveguide

The enhanced sensitivity of a guided mode biosensor is analyzed by employing double-layered porous silicon grating structures. The grating-coupled waveguide structure consists of two porous silicon grating layers with different refractive indices. simulations are carried out by changing the refractive index, which is due to the binding of biological molecules on the porous silicon pore can increase the refractive index of porous silicon. The numerical results show that this novel guided mode biosensor with a double-layered grating can provide not only a very high sensitivity but also a better reflectivity characteristic.