Creating Radially Polarized Light with Holograms
One of the important properties light beams possess is their polarization, which is the direction the waves rise and fall along. Controlling this property is quite valuable as different polarizations of light can behave differently. Researchers at the Harvard School of Engineering and Applied Sciences have recently designed a device capable of creating light with radial polarization using holograms and nanostructures.
Using nanostructures smaller than the wavelength of visible light, the researchers built a holographic device for controlling the properties of light. Holography deals with storing three-dimensional information within a two-dimensional structure using optical interference. By combining multiple structures, the device is able to control the intensity, polarization, and phase of light in the near-infrared and visible regions of the spectrum. It is even able to change circularly polarized light into radially polarized light, which is an uncommon polarization. Instead of oscillating up and down or side to side, radially polarized light oscillates in and out from a central point, which causes the beam to have a dark center.
As radially polarized light can be more tightly focused than more traditional polarizations, this device could see use in advanced microscopes and nanoparticle manipulation. For now though, the researchers are working to optimize the device to be more efficient.
Source: Harvard University