Voltage calibration of dual-frequency liquid crystal devices for infrared beam steering applications

Mahajan, Milind; Bing, Wei; Bhupathy, Vinay; Taber, Donald B.; Winker, Bruce K.

doi:10.1117/12.618096

Cited by 6 publications

(3 citation statements)

References 10 publications

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“…We also used a simple but effective dynamic calibration approach to test the device at refresh rate of 100 Hz. The details of calibration techniques are described elsewhere [7]. Further improvements are expected with ongoing work on improved calibration algorithms.…”

Section: Controller Electronicsmentioning

confidence: 99%

Compact 4 cm aperture transmissive liquid crystal optical phased array for free-space optical communications

et al. 2005

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There is a critical need for high bandwidth, high availability free-space optical communication links between the battlefield and the global information grid. Compact large aperture transceivers with low size, weight and power (SWaP) are needed to initiate and maintain communication links involving airborne platforms. The transceiver optical beam director typically contains fine and coarse steering stages. Existing beam director technology is based on electromechanical gimbaled mirrors with large SWaP that hinders deployment on many airborne platforms. To address the need for compact beam directors, we designed, fabricated, and tested an optical phased array (OPA) based on electrooptic dual frequency liquid crystal technology. This OPA has a transmissive architecture that enables a lower system SWaP, as compared to conventional reflective OPA. It has an 8 µm pixel pitch and steers over a 2.5° field of regard in one dimension at 1.55 µm. Two such OPAs can be stacked to steer in two dimensions. It has four independently addressable 1 cm x 4 cm regions arranged in a linear array to produce a continuous 4 cm x 4 cm aperture. The device incorporates novel addressing schemes to reduce the number of control channels by over an order of magnitude compared to conventional OPA addressing methods. It also utilizes proprietary low-loss transparent conductive Transcon TM film for low optical absorption in the infrared. The OPA uses a custom multi-channel controller circuit operating at a 500 Hz frame rate. We present results on OPA design, fabrication, and optical performance on steering.

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Section: Controller Electronicsmentioning

confidence: 99%

Compact 4 cm aperture transmissive liquid crystal optical phased array for free-space optical communications

et al. 2005

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“…The beam steering of LC-OPA in this experiment is to vary period A by controlling the number of phase shifters contained within one period of the grating. 10,31,32 The period of the grating of A ¼ Nd, d is the center distance of adjacent stripe electrodes, and N is the number of phase shifters. The grating is blazed to steer to the first order, m ¼ 1.…”

Section: Zone-fill Modulementioning

confidence: 99%

“…The diffraction angle can be expressed as sin β=mλA,where β is the steering angle, m is the order of steering associated with the grating, λ is the wavelength of light, and A is the period of the grating. The beam steering of LC-OPA in this experiment is to vary period A by controlling the number of phase shifters contained within one period of the grating 10 , 31 , 32 . The period of the grating of A=Nd, d is the center distance of adjacent stripe electrodes, and N is the number of phase shifters.…”

Section: System Implementationmentioning

confidence: 99%

Four-access, 80 mm aperture all phase-controlled liquid crystal laser antenna

Liang

Huang

et al. 2022

Opt. Eng.

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. High speed, wide range, and high precise beam steering technology are fundamental to free-space optical communication (FSO). Liquid crystal optical phased array (LC-OPA) is capable of achieving non-mechanical beam steering. This paper demonstrates a parallel, four-communication access beam deflection antenna based on LC-OPA, providing a large aperture, wide steering range, and high pointing precision. This antenna is composed of a coarse tracking subsystem using cascaded liquid crystal polarized grating (LCPG) and a fine tracking subsystem based on LC-OPA. The optical aperture is 80 mm × 80 mm, arranged in 2 × 2 subapertures, each serving a single wavelength beam. Besides, a cascaded control platform based on field programmable gate array is proposed to realize low-latency response. This optical antenna achieves a steering resolution of 20 μrad and covers a range of ±12 deg in two dimensions, laying the foundation for simultaneous access of multiple terminals in FSO communication network.

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Fast Photoluminescence Switching in the Nematic Phase of Calamitic–Discotic Composites

Madhuri

Rao

Yelamaggad

et al. 2015

Advanced Optical Materials

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A photoluminescent (PL) system comprising a host calamitic–nematic and discotic fluorescent dopant is presented which can be switched at fast rates between two anisotropic values of photoluminescence using a two‐frequency addressing scheme. The employed unprecedented protocol, exhibiting the desirable higher contrast, switches two orders of magnitude faster than the standard mode of addressing. The methodology employed can be generalized and thus caters to a variety of fluorophores to cover the required PL wavelength. On the basis of X‐ray diffraction results it is demonstrated that as the discotic content is increased, the extent and nature of the short‐range order in the nematic phase changes, from that of a standard nematic to that of the locally columnar type. Imposing geometrical restrictions on this active system through a network of hydrogen‐bonded nanoparticles yields higher emission in both the field‐on and field‐off situations, although with a reduced anisotropy.

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Voltage calibration of dual-frequency liquid crystal devices for infrared beam steering applications

Cited by 6 publications

References 10 publications

Compact 4 cm aperture transmissive liquid crystal optical phased array for free-space optical communications

Compact 4 cm aperture transmissive liquid crystal optical phased array for free-space optical communications

Four-access, 80 mm aperture all phase-controlled liquid crystal laser antenna

Fast Photoluminescence Switching in the Nematic Phase of Calamitic–Discotic Composites

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