Vector polarizers are a light filtering technology that is hidden behind the operation of many optical systems. They are in sunglasses, LCD screens, microscopes, microprocessors, laser machining and even more. Teams of optical physicists from Nanjing and Nankai University, China and the University of Central Florida, U.S. created a new vector polarizer design. This design is a huge advance in polarization technology because it allows for flexible filtering of a wide range of light sources and generation of new light states.
Light waves can oscillate with a back and forth motion that is oriented along different directions and its polarization describes the nature of this orientation. A traditional polarizer, like a polarized sunglasses lens, for example, filters out light oscillating along all but one direction. That filtered light is referred to as polarized light.
"An enormous challenge was how to solve the design and fabrication of vector polarizers to tailor the light beams and satisfy the requirements of various applications," said Hui-Tian Wang, an author of the study. Wang's group achieved a design that can tailor light intensity, phase and polarization. "The vector polarizer can significantly improve the generation efficiency of vector light beam and may be conducive to achieving a high-performance vector laser."
The advancements can be used to improve a variety of optical systems. In super-resolution microscopy, manipulating polarization can be used to achieve far-field focusing beyond normal diffraction limitations.
Physicists increased polarizer efficiency and flexibility by using a new liquid-crystal-based design that relies on birefringence. In birefringence, specific polarizations are filtered based on their refractive indexes. The team customized the orientation of liquid crystal molecules by using stringent photo-alignment techniques. They determined the dichroic dye film structure within the thin glass compartment before adding the liquid crystal.
The new vector polarizers feature manufacturing advantages.
"They are flexibly designed and easily fabricated, and have the advantages of the large-size complex structures and the broadband [light waves] operation," Wang said. "However, the vector polarizer we proposed still needs some improvements. For example, we need to improve its alignment quality, i.e., the quality of generated light beams. We also need to improve the spatial resolution for controlling the orientation of liquid crystal molecules."
Wang hopes that the vector polarizer’s ability to generate new polarized light states can be used in developing novel applications. For example, entangled vector photon states could be used in developing technology for quantum communications.
The paper on this research was published in APL Photonics.