In this paper, we propose an advanced hyperspectral video imaging system (AHVIS), which consists of an objective lens, an occlusion mask, a relay lens, an Amici prism and two cameras. An RGB camera is used for spatial reading and a gray scale camera is used for measuring the scene with spectral information. The objective lens collects more light energy from the observed scene and images the scene on an occlusion mask, which subsamples the image of the observed scene. Then, the subsampled image is sent to the gray scale camera through the relay lens and the Amici prism. The Amici prism that is used to realize spectral dispersion along the optical path reduces optical distortions and offers direct view of the scene. The main advantages of the proposed system are improved light throughput and less optical distortion. Furthermore, the presented configuration is more compact, robust and practicable.

We design and implement one type of guided mode resonance (GMR) circular grating filters (CGFs) on an HfO₂-on-silicon platform. Taking advantage of an angle-resolved micro-reflection measurement system, we achieve their incident angle- and polarization-dependent reflection spectra. For normal incident arbitrary linear polarization, a pair of reflection peaks is experimentally observed due to the coexistence of the azimuthal component E_a and the radial component E_r of the incident wave electric field (E-field). For oblique incident s-polarization (E-field perpendicular to the incident plane), the peak excited by the E_a component splits into two sub-peaks due to the removal of degeneracy, while that excited by the E_r component gradually fades away with the increase of the incident angle. For oblique incident p-polarization (E-field parallel to the incident plane), the spectrum appears to be reversed; that is, the peak corresponding to the E_r component gets split while that corresponding to the E_a component gradually disappears when the incident angle increases. Moreover, we experimentally demonstrate the spectral relationships between CGFs and linear grating filters under not only normal incidence but also oblique incidence; these relationships greatly facilitate the spectral design and tailoring of the CGFs.

This Letter describes a double-sided process to fabricate freestanding membrane devices on a GaN-on-silicon platform. The photoluminescence measurement is taken to characterize the optical performance. A large portion of the excited light from InGaN/GaN multiple quantum wells is trapped as waveguide modes and propagates in different directions. Experimental results show that the propagation direction of the waveguide mode can be converted into the direction normal to the surface at the edge of a freestanding membrane, and the emitted light is attenuated due to light propagation loss before it gets out from the edge. Subwavelength grating can also convert waveguide modes into air modes on a freestanding membrane. These results suggest that the emission efficiency can be greatly improved by employing more efficient light extraction methods and that GaN-based photonic waveguides are promising in the visible range.

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