Magnetically Actuated Liquid Crystals Could Lead to Novel Optical Devices
Liquid crystals are known for their use in LCD TVs, in which quickly changing electrical fields are used to control the molecular order of the liquid crystals. Liquid crystals can also be actuated by switching a magnetic field. Magnetic actuation does not require direct contact, whereas electrical actuation requires contact with electrodes. However, demonstrations of using magnetic fields to actuate liquid crystals have required extremely strong magnetic fields (~ 1 Tesla), limiting their practical use. Now, researchers from the University of California, Riverside have demonstrated that weak magnetic fields (1 milliTesla) can effectively actuate liquid crystals. The magnetically actuated liquid crystals exhibit a switching speed of less than 0.01 seconds (frequency above 100 Hz) - comparable to the performance of commercial liquid crystals based on electrical switching. With its advantageous features such as the electrode-less remote control of its optical properties and ability to fixate the liquid crystal orientation to create polarization patterns, the magnetically actuated liquid crystals could provide a new platform for fabricating other novel optical devices, including displays, waveguides, actuators, and optical modulators.