Shedding new light on Gravitational waves and the early Universe:

Discussion in 'Astronomy, Exobiology, & Cosmology' started by paddoboy, Dec 13, 2016.

  1. paddoboy Valued Senior Member

    Magnetic mirror could shed new light on gravitational waves and the early universe
    December 13, 2016

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    Researchers have created a new metamaterial half-wave plate operating at millimeter wavelengths that is less than 1-millimeter thick. When light reflects off the device, the polarization parallel to the wire-grid is reversed in its orientation, whereas the polarization perpendicular to it stays in the same direction. The overall effect is to create a differential phase-shift between orthogonal polarizations equal to 180 degrees. The rotation of the plate causes modulation of the polarization. Credit: Giampaolo Pisano, Cardiff University
    Researchers have created a new magnetic mirror-based device that could one day help cosmologists discover new details about ripples in space-time known as gravitational waves, particularly those emitted when the universe was extremely young.

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    Cosmic microwave background has been the subject of intense investigation since its discovery about 50 years ago. Recent years have seen an increased focus on the polarized components of this microwave background – in particular a component called B-mode, which is thought to hold the key to information about primordial gravitational waves and the physical processes that occurred very early in the history of the universe.

    In The Optical Society (OSA) journal Applied Optics, the researchers demonstrated a new type of polarization modulator based on a magnetic mirror. The new device could overcome a major challenge to detecting the B-mode polarization—the ability to modulate microwave polarization across a broad frequency range. Broadband operation is necessary to spectrally discriminate the extremely faint B-mode polarization from the foreground radiation of other astrophysical sources.

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    danshawen likes this.
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  3. paddoboy Valued Senior Member


    Multi-octave metamaterial reflective half-wave plate for millimeter and sub-millimeter wave applications:


    The quasi-optical modulation of linear polarization at millimeter and sub-millimeter wavelengths can be achieved by using rotating half-wave plates (HWPs) in front of polarization-sensitive detectors. Large operational bandwidths are required when the same device is meant to work simultaneously across different frequency bands. Previous realizations of half-wave plates, ranging from birefringent multi-plates to mesh-based devices, have achieved bandwidths of the order of 100%. Here we present the design and experimental characterization of a reflective HWP able to work across bandwidths of the order of 150%. The working principle of the novel device is completely different from any previous realization, and it is based on the different phase-shift experienced by two orthogonal polarizations reflecting, respectively, off an electric conductor and an artificial magnetic conductor.
    Xelasnave.1947 likes this.
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  5. danshawen Valued Senior Member

    That should make BICEP3 easier.
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