ABSTRACT
Hyperspectral imaging has a wide range of uses, from medical diagnostics to crop monitoring; however, conventional hyperspectral imaging systems are relatively slow, bulky, and rather costly. In this paper, we present an inexpensive, compact tunable optical filter for hyperspectral applications. The filter is based on a Fabry-Pérot interferometer utilizing hybrid metallic-dielectric mirrors and actuated using a MEMS electrostatic actuator. The optical filter is designed using the transfer matrix method; then, the results were verified by an electromagnetic wave simulator. The actuator is based on a ring-shaped parallel plate capacitor and is designed using COMSOL Multiphysics. An actuation displacement of 170 nm was used, which is the required distance to tune the filter over the whole visible range (400-700 nm). There are two designs proposed for the optical filter: the first was optimized to provide maximum transmission and the other is optimized to have minimum full-width-half-maximum (FWHM) value. The first design has a maximum transmission percentage of 94.45% and a minimum transmission of 86.34%; while the minimum FWHM design had an average FWHM value of 7.267 nm. The results showed improvements over the current commercial filters both in transmission and in bandwidth.
ABSTRACT
This work presents a technique for the design of visible optical filters using a hybrid plasmonic insulator-metal-insulator (IMI) structure. The proposed IMI visible light filter exhibits high transmission (â¼91%) and an insertion loss of â¼0.4 dB with almost an omnidirectional field-of-view (0°-70°), a feature that is important for light collection in miniaturized devices. The proposed design also has a minimal polarization dependent loss of 0.2 dB at an angle of incidence of 60°. The effects of design parameters on the filter's performance are studied. Design rules of the filter are deduced along with physical justifications of the obtained results.
ABSTRACT
This work presents what we believe is a novel design of a hybrid plasmonic-transmission blue filter for visible light communication systems that employ yellow phosphor-coated blue light-emitting diodes. The proposed filter balances the trade-off between transmission performance and tolerance to variation in angles of incidence (AOIs) while maintaining a low cost with limited complexity design. The designed filter operation is based upon quasi-plasmon mode excitation in a hybrid structure of alternating layers of silver and titanium dioxide over a silica substrate. A primary design approach for a hybrid plasmonic filter of five alternating layers is illustrated in detail. Needle optimization technique is further applied to achieve the required filter performance. The designed filter has an insertion loss of â¼1 dB over a spectral range of 400-485 nm and a minimal close to zero polarization-dependent loss for a wide range of AOI (slightly above 50°). The tolerance of the proposed design against fabrication errors is also tested. The performances of the proposed filters are tested for individual and simultaneous variations from the designed thicknesses, with a ±10% standard deviation from each layer's thickness.
ABSTRACT
In this work, the performance of a nonconventional IR surface plasmon resonance (SPR) gas sensor structure based on the use of a metal-insulator-metal (MIM) structure is studied. This MIM-based sensor structure gives enhanced performance five times better than the conventional MI SPR optical gas sensors. The performance of the SPR gas sensors is studied under the effect of oblique incident Gaussian beams with different spot sizes, and the performance enhancement of the MIM structure is confirmed for different spot sizes. The simulation technique used to generate the results is also verified by comparing them to actual experimental results available in the literature.
