1. Ferroelectric liquid-crystal modulator with large switching rotation angle for polarization-independent binary phase modulation.
- Author
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Nabadda, Esther, Bennis, Noureddine, Czerwinski, Michał, Walewska, Aleksandra, Jaroszewicz, Leszek R., Sánchez-López, María del Mar, and Moreno, Ignacio
- Subjects
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PHASE modulation , *FERROELECTRIC liquid crystals , *ROTATIONAL motion , *DIFFRACTIVE optical elements , *OPTICAL polarization , *REVERSE engineering , *OPTICAL devices - Abstract
• In this work, we study a ferroelectric liquid crystal (FLC) cell as a phase-only modulator. The novelty of the approach is the use of a FLC cell with a large switching rotation angle close to 90° instead of the typical value used in display applications, which is less than 45 ∘. • We show that when the LC layer is a half-wave retarder, this device provides a binary π phase modulation for any input state of polarization and with maximum light conversion efficiency, thus being useful even for unpolarized light. This situation is not possible with the common nematic LC modulators or with standard FLC modulators of smaller rotation angles. • The main physico-chemical properties of the liquid crystalline mixture used to fabricate the FLC modulator are studied. In addition, we perform a reverse engineering procedure aimed at verifying the modulator's physical parameters and the binary π -phase modulation. In this work a ferroelectric liquid crystal (FLC) modulator with a non-standard large switching rotation angle, close to 90 ∘ , is fabricated and characterized. The modulator acts as a switchable wave-plate with an in-plane rotation of the principal axis under the action of a bipolar voltage. In the ideal situation of half-wave retardance, the device is shown to behave as a binary π phase modulator independently of the input state of polarization. We provide physico-chemical properties of the liquid crystalline mixture used to fabricate the FLC modulator with such large switching angle. The characterization method of the device optical properties is presented, which allows the localization of the two LC stable states, the unambiguous determination of the rotation angle, and the evaluation of the spectral retardance function. We demonstrate the polarization-independent π phase shift using an adapted Young's type interferometer for real-time measurements, where we further analyze the operational frequency limits of the device. This FLC operational mode can be exploited to produce binary-phase polarization-independent diffractive optical elements. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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