Phys.org August 14, 2021 A team of researchers in the US (Harvard University, industry) has proposed a new class of computer-generated holograms, called Jones matrix holograms, whose far-fields have designer-specified polarization response. They have provided a simple procedure for their implementation using form-birefringent metasurfaces. Jones matrix holography generalizes past work with a consistent mathematical framework, particularly in the field of metasurfaces. They have demonstrated holograms whose far-fields implement parallel polarization analysis and custom waveplate-like behavior. The new approach could lead to applications in diverse fields including imaging, microscopes, displays, and astronomy. The work shows that the ability to switch between […]
Tag Archives: Light
Engineers bend light to enhance wavelength conversion
Nanowerk July 30, 2021 Incoming light can hit the electrons in the semiconductor lattice and move them to a higher energy state creating an electric field which further accelerates the high-energy electrons. They unload the extra energy by radiating it at different optical wavelengths, thus converting the wavelengths. An international team of researchers (USA – UCLA, Iowa State University, Germany) devised a solution for improving wavelength conversion using the semiconductor surface state phenomenon. They incorporated a nanoantenna array that bends incoming light, so it is confined around the shallow surface of the semiconductor converting the wavelength easily and without any […]
Harnessing the dark side
Nanowerk July 13, 2021 Optical singularities, which appear completely dark, typically occur when the phase of light with a specific wavelength, or color, is undefined. Researchers at Harvard University have developed a new way to control and shape optical singularities. The metasurface tilts the wavefront of light in a very precise manner over a surface so that the interference pattern of the transmitted light produces extended regions of darkness. Their approach allows precise engineering of dark regions with remarkably high contrast. Engineered singularities could be used to trap atoms in dark regions and improve super high-resolution imaging. As darkness has […]
Scientists demonstrate perfect light absorption by single nanoparticle
Nanowerk June 15, 2021 Previously researchers succeeded in demonstrating the phenomenon of perfect absorption in large bodies of matter that were several times the size of a light beam. But the question remained unsolved was – whether the same was possible for miniature objects. An international team of researchers (Russia, Sweden) calculated the properties of a small object that could completely absorb all incidental light. They succeeded in reducing this complex analytical task to a simpler one – a Fredholm integral equation of the second kind. Having solved it, they found the ideal combination of particle and light properties that […]
Trapping light without back reflections
Phys.org January 4, 2021 Due to material imperfections, some amount of light is reflected backwards in microresonators which disturbs their function. To reduce the unwanted backscattering an international team of researchers (UK, Germany) used the principle of noise cancelling headphone and introduced out-of-phase light to cancel out optical interference. To generate the out-of-phase light, the researchers position a sharp metal tip close to the microresonator surface. The tip also causes light to scatter backwards. As the phase of the reflected light can be chosen by controlling the position of the tip, backscattered light’s phase can be set so it annihilates […]
Tailored meta-grid of nanoparticles boosting performance of light-emitting diodes
Phys.org July 29, 2020 Current methods to use new materials for increasing LED light output are has led to the LED chips becoming bulkier or costly to manufacture. According to a theoretical model proposed by researchers in the UK a significant enhancement in light extraction from LEDs can be achieved by boosting the transmission across LED-chip/encapsulant interface. They propose introducing a monolayer of plasmonic nanoparticles on top of the LED chip which can reduce the Fresnel reflection loss at the chip/encapsulant interface. A similar effect is also applicable for enhancing the trapping of light in solar cells…read more. Open Access […]
Cutting through fog with laser focus
Phys.org January 7, 2020 Most of the previous studies demonstrated spatial focusing to the speckle grain size, and manipulation of the temporal properties of the achieved focus. Researchers in Australia demonstrate an approach to control the total temporal impulse response, not only at a single speckle grain but overall spatial degrees of freedom (spatial and polarization modes) at any arbitrary delay time through a multimode fiber. Global enhancement or suppression of the total light intensity exiting a multimode fibre is shown for arbitrary delays and polarization states. This work could benefit to applications that require pulse delivery in disordered media, […]