Abstract
We propose and demonstrate a fast-response liquid crystal (LC) variable optical retarder or attenuator with several transmission levels. The fast-response LC optical device consists of dual π -cells. The device is designed so that the transition between any two states is controlled by the application of an increased voltage level rather than by applying a lower level. This design offers transition times in the range of tens of microseconds between any transmission states. A limitation of the device is that the time between transitions cannot be arbitrarily short and is typically milliseconds.
Highlights
IntroductionA fast-response liquid crystal (LC) optical retarder or an attenuator with multilevel transmission is needed for many applications, where LC devices are considered to be too slow [e.g., in the field of optical communications or for field sequential three-dimensional (3-D) displays of the future]
A fast-response liquid crystal (LC) optical retarder or an attenuator with multilevel transmission is needed for many applications, where LC devices are considered to be too slow [e.g., in the field of optical communications or for field sequential three-dimensional (3-D) displays of the future].The response time of conventional nematic LC devices is usually in the range of milliseconds
If we would like to decrease the response time for the first case, an approach is just to apply a higher voltage during the transition, but the response time of the second case is limited by the material properties of the LC material that cannot be chosen at will
Summary
A fast-response liquid crystal (LC) optical retarder or an attenuator with multilevel transmission is needed for many applications, where LC devices are considered to be too slow [e.g., in the field of optical communications or for field sequential three-dimensional (3-D) displays of the future]. Haven[9] has suggested a device modification that solves the problem of having the response time controlled by the voltage-removed transition He has shown that in a device that consists of two crossed LC cells, that it is possible to have both the optical transition between a state of increased light transmission, and to a state of decreased light transmission be controlled by the response time of the voltageapplied liquid crystal director transition. This is made possible by “optically hiding” the voltage-removed transition by configuring the device, so that it is possible that while the two cells are relaxing together, the net retardation of the device stays zero by having the two cells have the same retardation at each time point during the relaxation. The device can be used directly as a variable retarder or with polarizers to provide a high-speed multilevel optical attenuator
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