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Alfonso A. Castrejón-pita

Publications and source records attributed to Alfonso A. Castrejón-pita.

2 recordsLinked to original sources

Full vectorial field sensing using liquid crystal droplet arrays

Determining the amplitude, phase, and polarization profile of light is essential for both fundamental scientific discovery and applications spanning optical metrology, microscopy, astronomy, and optical communication/computing technologies. However, most modern measurement approaches are unable to retrieve such parameters readily, often relying on bulky and expensive hardware, or lacking the capability for single-shot sensing. Here, we introduce a low cost, compact, full vectorial field sensor based on an inkjet-printed nematic liquid crystal droplet array that enables simultaneous measurement of these important characteristics of light. Polarization and intensity are measured via division-of-wavefront polarimetry, exploiting the droplets' spatially varying birefringence, while the phase is reconstructed by treating each droplet as a separate microlens in a Shack-Hartmann-like wavefront sensor configuration. To demonstrate the system's performance, we characterize aberrated dual-wavelength beams carrying distinct intensity, phase, and polarization information, confirming accurate retrieval of the optical field profiles for both spectral components.

physics.optics↗

Complex structured light generation using printed liquid crystal droplets

Inkjet-printed liquid crystal (LC) droplets exhibit an intricate spatially-varying birefringence due to their complex internal director configuration. While such anisotropy is often viewed as a drawback when LC droplets are used as microlenses, here we leverage this remarkable birefringence property to generate complex structured light. Through a selection of the alignment layer, and by varying the chiral pitch, we create three distinct droplet types with tailored intrinsic director configurations, each exhibiting a unique birefringence distribution for structured light beam generation. We show that these printed LC droplets can generate beams that exhibit skyrmionic structures carrying two units of orbital angular momentum, beams that contain azimuthal/radial polarized fields, and beams with polarization singularities. Our method enables new possibilities for using LC droplet technology to engineer sophisticated optical beam patterns.

physics.optics↗