Phys. Rev. Lett. 111, 107802 (2013)

Because of their ability to change the polarization of light waves on application of an electric field, nematic liquid crystals form the basis of flat-screen displays in many kinds of consumer electronic devices. This polarization change typically occurs as a result of the electrically induced reorientation of molecules caused by the dielectric anisotropy of the material. However, this process, called the Frederiks effect, can be relatively slow with relaxation from the field-on to the field-off state taking milliseconds. Now, Volodymyr Borshch and co-workers from Kent State University in the USA have reported a new electro-optic effect in liquid crystals that offers a switching time of the order of tens of nanoseconds or even nanoseconds. When a He–Ne laser beam with a wavelength of 633 nm and polarized at 45° to the plane of incidence strikes a nematic liquid crystal (CCN-47) cell at 45°, the team observed that field-induced changes in birefringence follow both the 'on' and 'off' edges of the applied rectangular voltage pulses with a response time of about 30 ns. According to them, the electro-optic effect is caused by the electric-field-induced modification of the order parameters (optic tensor) rather than Frederiks reorientation. The nanosecond switching ability of nematic liquid crystals may contribute to fundamental science and suggest new design options for displays.