Stacked subwavelength gratings as circular polarization filters

Deguzman, Panfilo C.; Nordin, Gregory P.

doi:10.1364/ao.40.005731

Cited by 47 publications

(20 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Second, a multilevel design would provide more parameters to aid the design of an achromatic waveplate 29 . Additionally, stacked gratings could help facilitate the incorporation of a diffractive waveplate with the other elements required for the polarimeter system 17 . Finally, a two dimensional grating design would also provide additional parameters that may prove useful in designing an achromatic element.…”

Section: Discussionmentioning

confidence: 99%

Micropolarizing device for long wavelength infrared polarization imaging.

Wendt¹,

Carter²,

Samora³

et al. 2006

View full text Add to dashboard Cite

The goal of this project is to fabricate a four-state pixelated subwavelength optical device that enables mid-wave infrared (MWIR) or long-wave infrared (LWIR) snapshot polarimetric imaging. The polarization information can help to classify imaged materials and identify objects of interest for numerous remote sensing and military applications.While traditional, sequential polarimetric imaging produces scenes with polarization information through a series of assembled images, snapshot polarimetric imaging collects the spatial distribution of all four Stokes' parameters simultaneously. In this way any noise due to scene movement from one frame to the next is eliminated.We fabricated several arrays of subwavelength components for MWIR polarization imaging applications. Each pixel unit of the array consists of four elements. These elements are micropolarizers with three or four different polarizing axis orientations. The fourth element sometimes has a micro birefringent waveplate on the top of one of the micropolarizers. The 4 linear micropolarizers were fabricated by patterning nano-scale metallic grids on a transparent substrate. A large area birefringent waveplate was fabricated by deeply etching a subwavelength structure into a dielectric substrate. The principle of making linear micropolarizers for long wavelengths is based upon strong anisotropic absorption of light in the nano-metallic grid structures. The nano-metallic grid structures are patterned with different orientations; therefore, the micropolarizers have different polarization axes. The birefringent waveplate is a deeply etched dielectric one-dimensional subwavelength grating; therefore two orthogonally polarized waves have different phase delays. Finally, in this project, we investigated the near field and diffractive effects of the subwavelength element apertures upon detection.The fabricated pixelated polarizers had a measured extinction ratios larger than 100:1 for pixel sizes in the order of 15 μm by 15 μm that exceed by 7 times previously reported devices.The fabricated birefringent diffractive waveplates had a total variation of phase delay rms of 9.41 degrees with an average delay of 80.6 degrees across the MWIR spectral region.We found that diffraction effects change the requirement for separation between focal plane arrays (FPA) micropolarizer arrays and birefringent waveplates arrays, originally in the order of hundreds of microns (which are the typical substrate thickness) to a few microns or less. This new requirement leads us to propose new approaches to fabricate these devices.5

show abstract

Section: Discussionmentioning

confidence: 99%

Micropolarizing device for long wavelength infrared polarization imaging.

Wendt¹,

Carter²,

Samora³

et al. 2006

View full text Add to dashboard Cite

show abstract

“…ZOGs behave like homogeneous media with interesting optical properties, which can be used to e.g. synthesize artificial birefringent achromatic waveplates 19,20 or monolithic anti-reflective structures.…”

Section: -25mentioning

confidence: 99%

Taking the vector vortex coronagraph to the next level for ground- and space-based exoplanet imaging instruments: review of technology developments in the USA, Japan, and Europe

et al. 2011

View full text Add to dashboard Cite

The Vector Vortex Coronagraph (VVC) is one of the most attractive new-generation coronagraphs for ground-and space-based exoplanet imaging/characterization instruments, as recently demonstrated on sky at Palomar and in the laboratory at JPL, and Hokkaido University. Manufacturing technologies for devices covering wavelength ranges from the optical to the mid-infrared, have been maturing quickly. We will review the current status of technology developments supported by NASA in the USA (Jet Propulsion Laboratory-California Institute of Technology, University of Arizona, JDSU and BEAMCo), Europe (University of Liège, Observatoire de ParisMeudon, University of Uppsala) and Japan (Hokkaido University, and Photonics Lattice Inc.), using liquid crystal polymers, subwavelength gratings, and photonics crystals, respectively. We will then browse concrete perspectives for the use of the VVC on upcoming ground-based facilities with or without (extreme) adaptive optics, extremely large ground-based telescopes, and space-based internal coronagraphs.

show abstract

“…Though multigrid structures have been studied for many applications [4], [5], there is only one report published recently that suggests a possibility of multiplication of extinction ratio of two polarizers in tandem [6]. In that instance, however, the authors based their conclusions on Mueller matrices of abstract polarizers that do not account for the correct selfconsistent solution of the electromagnetic problem and, as a result, missed a range of frequency-selective properties (the fact that the extinction ratio increases at certain frequencies while decreases at others, the dependence of the effect on transmission or reflection mode of operation, etc).…”

Section: Introductionmentioning

confidence: 99%