Performance of conformal guided mode resonance filters.
ABSTRACT Guided mode resonance (GMR) filters are highly functional micro-optics capable of narrowband spectral filtering. GMR devices have previously been demonstrated on flat substrates using a wide range of materials and configurations. In this Letter, we apply a soft lithographic technique followed by the deposition of dielectric layers to generate GMR filters on a concave lens surface. Resonances of the resulting conformal GMR filters are experimentally measured and characterized, and the results are compared to the performance of similar GMR filters fabricated on flat surfaces.
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ABSTRACT: We demonstrate the design of an efficient angle-insensitive guided mode resonance filter (GMRF), with narrow bandwidth and low sideband reflection, for TE-polarized waves. The reflection properties of the multilayer structure have been studied, and the results verify that the thin film design of the gradient-index layer is important for the realization of an angle-insensitive filter. Various gradient coefficients of the thin film have distinct effects on the reflection spectrum. For an increasing incident angle, although the line-shape symmetry becomes less perfect, the positions of the resonant peak remain the same. The GMRF proposed here has many desirable attributes that lends itself to being an excellent platform, for devices such as lasers, detectors, filters, and sensors.Optics Letters 10/2014; 39(20). DOI:10.1364/OL.39.005929 · 3.18 Impact Factor
Conference Paper: Small-aperture guided-mode-resonance filter with cavity resonators[Show abstract] [Hide abstract]
ABSTRACT: A cavity-resonator-integrated guided-mode-resonance filter (CRIGF) consisting of a grating coupler (GC) and a pair of distributed-Bragg-reflectors (DBRs) on a thin film waveguide has been recently proposed and investigated to provide a narrow-band reflection spectrum for an incident wave of a small beam width from the free space. A CRIGF demonstrated so far shows polarization dependence because propagation constants of guided waves excited by GC are different between TE and TM incident waves. In order to construct a polarization-independent guided-mode resonance filter with small aperture, an integration of two CRIGFs crossed each other was proposed and discussed in this paper. A device was designed for a resonance wavelength of 1550 nm and its reflection and transmission spectra were predicted by a newly developed analysis based on the coupled-mode theory. A reflectance of 96 % with 1 nm bandwidth was expected for an incident beam diameter of 10 μm. A test sample working at 846 nm was fabricated and characterized. A Ge:SiO2 guiding core layer was deposited on a SiO2 glass substrate, and GC and DBRs were formed by the electron-beam direct writing lithography. Measured reflection spectra for TE and TM incident beams were well coincident with each other.Electronic Components and Technology Conference (ECTC), 2012 IEEE 62nd; 01/2012
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ABSTRACT: When a suitably designed waveguide grating couples an external wave to a local wave, a well-known (and well-studied) resonance anomaly can appear in the reflectance spectrum. We employ a guided mode resonance in a silicon-on-insulator waveguide to study the spectral phase response using backside illumination, in which interference fringes from a weak substrate reflection allows the extraction of the phase. Comparing a slab analysis, rigorous coupled wave analysis, and experiment shows that the strongest resonances in this structure are associated with modes confined in the silicon layer that are very close to cut-off.Journal of Modern Optics 09/2014; 62(2):97-103. DOI:10.1080/09500340.2014.951701 · 1.17 Impact Factor