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1. Inverse-Designed Photonic Polarization Control for High-Density Integration on Foundry Platforms

   A. Khurana, J. B. ( April 2023 , Silicon Photonics Conference)

   Compact, wideband structures to enable chip-scale polarization control are essential elements for large-scale integrated photonics. We experimentally validate inversedesigned polarization control structures fabricated on a commercial foundry, demonstrating rotator conversion efficiency of -1.5dB and splitter insertion losses of 1.4dB (TE) and 2.6dB (TM) across C-band 

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2. Laser-controlled projection of quantum dot dipoles using metal-oxide plasmonic metastructures: maintaining spin polarization memory

   https://doi.org/10.1039/d1tc02532e  

   Sadeghi, Seyed M. ; Wing, Waylin ; Gutha, Rithvik R. ; Sharp, Christina ; Roberts, Dustin ; Mao, Chuanbin ( October 2021 , Journal of Materials Chemistry C)

   It is known that the spontaneous emission of semiconductor quantum dots is mostly unpolarized when they are excited off-resonantly. The complete loss of polarization memory is associated with the ultrafast carrier scattering, leading to complete spin polarization relaxation. We study the application of metal-oxide plasmonic double-junction structures to transfer the excitation polarization memory of quantum dots to their spontaneous emission. These structures consist of arrays of metallic nanoantennas in the presence of heterostructures consisting of Au/Si Schottky junctions and Si/Al-oxide charge barriers. Our results show that by using such double-junction structures, one can control the states of polarization and intensity of the emission of quantum dots using the state of polarization of an off-resonant laser field. For achieving this, we explore the optical control of exciton–plasmon coupling using optical lattice modes caused by the arrays of metallic nanoantennas, and the application of the electrostatic field generated by the hot electrons captured at the Au/Si Schottky junction. 

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3. Generalized polarization transformations with metasurfaces

   https://doi.org/10.1364/OE.442844  

   Zaidi, Aun ; Rubin, Noah_A ; Dorrah, Ahmed_H ; Park, Joon-Suh ; Capasso, Federico ( November 2021 , Optics Express)

   Metasurfaces are arrays of sub-wavelength spaced nanostructures, which can be designed to control the many degrees-of-freedom of light on an unprecedented scale. In this work, we design meta-gratings where the diffraction orders can perform general, arbitrarily specified, polarization transformation without any reliance on conventional polarization components, such as waveplates and polarizers. We use matrix Fourier optics to design our devices and introduce a novel approach for their optimization. We implement the designs using form-birefringent metasurfaces and quantify their behavior – retardance and diattenuation. Our work is of importance in applications, such as polarization abberation correction in imaging systems, and in experiments requiring novel and compact polarization detection and control.

    

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4. Patterning of Lyotropic Chromonic Liquid Crystals by Photoalignment with Photonic Metamasks

   https://doi.org/10.1002/adma.201606112  

   Peng, Chenhui ; Guo, Yubing ; Turiv, Taras ; Jiang, Miao ; Wei, Qi‐Huo ; Lavrentovich, Oleg D. ( March 2017 , Advanced Materials)

   Controlling supramolecular self‐assembly in water‐based solutions is an important problem of interdisciplinary character that impacts the development of many functional materials and systems. Significant progress in aqueous self‐assembly and templating has been demonstrated by using lyotropic chromonic liquid crystals (LCLCs) as these materials show spontaneous orientational order caused by unidirectional stacking of plank‐like molecules into elongated aggregates. In this work, it is demonstrated that the alignment direction of chromonic assemblies can be patterned into complex spatially‐varying structures with very high micrometer‐scale precision. The approach uses photoalignment with light beams that exhibit a spatially‐varying direction of light polarization. The state of polarization is imprinted into a layer of photosensitive dye that is protected against dissolution into the LCLC by a liquid crystalline polymer layer. The demonstrated level of control over the spatial orientation of LCLC opens opportunities for engineering materials and devices for optical and biological applications.

    

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5. Birefringent Fourier filtering for single molecule coordinate and height super-resolution imaging with dithering and orientation

   https://doi.org/10.1038/s41467-020-19064-6  

   Curcio, Valentina ; Alemán-Castañeda, Luis A. ; Brown, Thomas G. ; Brasselet, Sophie ; Alonso, Miguel A. ( October 2020 , Nature Communications)

   Super-resolution imaging based on single molecule localization allows accessing nanometric-scale information in biological samples with high precision. However, complete measurements including molecule orientation are still challenging. Orientation is intrinsically coupled to position in microscopy imaging, and molecular wobbling during the image integration time can bias orientation measurements. Providing 3D molecular orientation and orientational fluctuations would offer new ways to assess the degree of alignment of protein structures, which cannot be monitored by pure localization. Here we demonstrate that by adding polarization control to phase control in the Fourier plane of the imaging path, all parameters can be determined unambiguously from single molecules: 3D spatial position, 3D orientation and wobbling or dithering angle. The method, applied to fluorescent labels attached to single actin filaments, provides precisions within tens of nanometers in position and few degrees in orientation.

    

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