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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. L1448 IRS3B: Dust Polarization Aligned with Spiral Features, Tracing Gas Flows

   https://doi.org/10.3847/1538-4357/adcb9f  

   Looney, Leslie W; Lin, Zhe-Yu Daniel; Li, Zhi-Yun; Tobin, John J; Radecki, Martin; Butte, Syzygy; Stephens, Ian W; Fernández-López, Manuel; Yang, Haifeng; Reynolds, Nickalas K; et al (May 2025, The Astrophysical Journal)

   Abstract Circumstellar disk dust polarization in the (sub)millimeter is, for the most part, not from dust grain alignment with magnetic fields but rather indicative of a combination of dust self-scattering with a yet unknown alignment mechanism that is consistent with mechanical alignment. While the observational evidence for scattering has been well established, that for mechanical alignment is less so. Circum-multiple dust structures in protostellar systems provide a unique environment to probe different polarization alignment mechanisms. We present ALMA Band 4 and Band 7 polarization observations toward the multiple young system L1448 IRS3B. The polarization in the two bands are consistent with each other, presenting multiple polarization morphologies. On the size scale of the inner envelope surrounding the circum-multiple disk, the polarization is consistent with magnetic field dust grain alignment. On the very small scale of compact circumstellar regions, we see polarization that is consistent with scattering around sourceaandc, which are likely the most optically thick components. Finally, we see polarization that is consistent with mechanical alignment of dust grains along the spiral dust structures, which would suggest that the dust is tracing the relative gas flow along the spiral arms. If the gas-flow dust grain alignment mechanism is dominant in these cases, disk dust polarization may provide a direct probe of the small-scale kinematics of the gas flow relative to the dust grains. 

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4. DNA origami directed nanometer-scale integration of colloidal quantum emitters with silicon photonics

   https://doi.org/10.1101/2025.01.23.634416  

   Luo, Xin; Ranno, Luigi; Sverko, Tara; Lee, Jae Young; Sbalbi, Nicholas; Jones, Annette; Chen, Chi; Bawendi, Moungi G; Hu, Juejun; Macfarlane, Robert J; et al (January 2025, bioRxiv)

   Abstract Incorporation of colloidal quantum emitters into silicon-based photonic devices would enable major advances in quantum optics. However, deterministic placement of individual sub-10 nm colloidal particles onto micron-sized photonic structures with nanometer-scale precision remains an outstanding challenge. Here, we introduce Cavity-Shape Modulated Origami Placement (CSMOP) that leverages the structural programmability of DNA origami to precisely deposit colloidal nanomaterials within lithographically-defined resist cavities. CSMOP enables clean and accurate patterning of origami templates onto photonic chips with high yields. Soft-silicification-passivation stabilizes deposited origamis, while preserving their binding sites to attach and align colloidal quantum rods (QRs) to control their nanoscale positions and emission polarization. We demonstrate QR integration with photonic device structures including waveguides, micro-ring resonators, and bullseye photonic cavities. CSMOP therefore offers a general platform for the integration of colloidal quantum materials into photonic circuits, with broad potential to empower quantum science and technology. 

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5. Toward Atomic-Scale Control over Structural Modulations in Quasi-1D Chalcogenides for Colossal Optical Anisotropy

   https://doi.org/10.1021/acsnano.5c07992  

   Ren, Guodong; Singh, Shantanu; Jung, Gwan Yeong; Choi, Wooseon; Chen, Huandong; Zhao, Boyang; Ye, Kevin; Lupini, Andrew R; Chi, Miaofang; Hachtel, Jordan A; et al (October 2025, ACS Nano)

   Optically anisotropic materials are sought after for tailoring the polarization of light. Recently, colossal optical anisotropy (Δn = 2.1) was reported in a quasi-one-dimensional chalcogenide, Sr9/8TiS3. Compared to SrTiS3, the excess Sr in Sr9/8TiS3 leads to periodic structural modulations and introduces additional electrons, which undergo charge ordering on select Ti atoms to form a highly polarizable cloud oriented along the c-axis, hence resulting in the colossal optical anisotropy. Here, further enhancement of the colossal optical anisotropy to Δn = 2.5 in Sr8/7TiS3 is reported through control over the periodicity of the atomic-scale modulations. The role of structural modulations in tuning the optical properties in a series of SrxTiS3 compounds with x = [1, 9/8, 8/7, 6/5, 5/4, 4/3, 3/2] is investigated using density-functional-theory (DFT) calculations. The structural modulations arise from various stacking sequences of face-sharing TiS6 octahedra and twist-distorted trigonal prisms and are found to be thermodynamically stable for 1 < x < 1.5. As x increases, an indirect-to-direct band gap transition is predicted for x ≥ 8/7 along with an increased occupancy of Ti-dz2 states. Together, these two factors result in a theoretically predicted maximum birefringence of Δn = 2.5 for Sr8/7TiS3. Single crystals of Sr8/7TiS3 were grown using a molten-salt flux method. Single-crystal X-ray diffraction measurements confirm the presence of long-range order with a periodicity corresponding to Sr8/7TiS3, which is further corroborated by atomic-scale observations using scanning transmission electron microscopy. Polarization-resolved Fourier-transform infrared spectroscopy of Sr8/7TiS3 crystals shows Δn ≈ 2.5, in excellent agreement with the theoretical predictions. Overall, these findings demonstrate the compositional tunability of optical properties in SrxTiS3 compounds by control over atomic scale modulations and suggest that similar strategies could be extended to other compounds having modulated structures. 

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