Electrically Controllable Liquid Crystal Component for Efficient Light Steering

Abstract

In this paper, we present an electrically controllable microoptical component for light beam steering and light intensity distribution built on the combination of nematic liquid crystal (LC) and polymer microprisms. Polymer microprism arrays are fabricated using soft embossing with elastic polydimethylsiloxane molds and ultraviolet curable resins. Surface profiling measurements show that the dimensions of the replicated prisms closely approximate those of the master prism. Two different LC alignment techniques were employed: hybrid rubbing alignment and obliquely evaporated SiO 2 alignment, both of which result in proper alignment of the LC molecules along the prism groove direction. The operation voltage of the LC components is relatively low (10 V rms ). The steering angle of a green laser beam was experimentally studied as a function of applied voltage, and a steering range of 3 was found. The active LC components also effectively deflect a collimated white light beam over a steering angle of about 2 with an efficiency of 27%-33%. All the optical measurements are in agreement with theoretical calculations based on Snell's law.

Fast switching cholesteric liquid crystal optical beam deflector with polarization independence

“…When the laser beam is normally incident on the LC device having the P state, due to the refractive index difference between the DFCh-LC and the grating, the maximum intensity appears on the +1 st order, while if the device is in the H state due to the application of a voltage of 150  V pp , the maximum intensity is found to be at the −1 st order. Using the first order approximation angle derivation method 13 , the beam steering angles are obtained to be 0.61° and −0.24° respectively for the P state and the H state of the DFCh-LC-grating beam steering devices.

Figure 3Schematic setup for optical measurements of Ch-LC-grating devices.

Figure 4Green laser beam deflection by DFCh-LC-grating beam steering devices with ( a ) the P state and ( b ) the H state.

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Liquid Crystal Beam Steering Devices: Principles, Recent Advances, and Future Developments

“…The fabricated PMMA blazed gratings are much larger, such that applying the same mechanism (variable diffraction order blazed grating), the imprinted blazed gratings can switch among higher orders. Two configurations have been proposed; namely, the transmissive [48] and reflective [49] modes, as shown in Figures 6a and 6b, respectively. In transmissive mode, the voltage-off state provides the highest steering angle.…”

Reflective liquid crystal hybrid beam-steerer

“…Several researchers have fabricated devices of this kind [11][12][13]. Computational analyses to obtain the diffraction efficiency for this type of device has been undertaken for a binary grating structure via the rigorous coupled-wave analysis [11].…”

“…Computational analyses to obtain the diffraction efficiency for this type of device has been undertaken for a binary grating structure via the rigorous coupled-wave analysis [11]. Recently liquid crystal beam steerers of the hybrid type have been reported and demonstrated, in which the structured polymer layer was formed using soft-embossing, a technique suitable for mass production with roll-to-roll processing [12].…”