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1. Response of wavelength-shifting and scintillating-wavelength-shifting fibers to ionizing radiation

   https://doi.org/10.1088/1748-0221/21/03/P03053  

   Bae, W; Cesar, J; Chen, K; Cho, J; Du, D; Edgar, J; Earthman, W; Falana, OM; Gajda, M; Hurlbut, C; et al (March 2026, Journal of Instrumentation)

   Abstract We report results of characterizing the response and light transport of wavelength-shifting (WLS) and scintillating-wavelength-shifting (Sci-WLS) fibers under irradiation by radioactive α, β, and γ sources. Light yield and light transmission were measured for the WLS fiber BCF-91A from Saint-Gobain and for a new Sci-WLS fiber EJ-160 from Eljen Technology. The two variants with different fluor mixtures, EJ-160I and EJ-160II, exhibited approximately five and seven times higher light yield than BCF-91A, respectively, while their attenuation lengths were 3.80 m for BCF-91A, 4.00 m for EJ-160I, and 2.50 m for EJ-160II. 

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2. Spectroscopic Microtomography in the Short-Wave Infrared Wavelength Range

   https://doi.org/10.3390/s23115164  

   Juntunen, Cory; Abramczyk, Andrew R.; Shea, Peter; Sung, Yongjin (June 2023, Sensors)

   Spectroscopic microtomography provides the ability to perform 4D (3D structural and 1D chemical) imaging of a thick microscopic specimen. Here, we demonstrate spectroscopic microtomography in the short-wave infrared (SWIR) wavelength using digital holographic tomography, which captures both the absorption coefficient and refractive index. A broadband laser in tandem with a tunable optical filter allows us to scan the wavelength from 1100 to 1650 nm. Using the developed system, we measure human hair and sea urchin embryo samples. The resolution estimated with gold nanoparticles is 1.51 μm (transverse) and 1.57 μm (axial) for the field of view of 307 × 246 μm2. The developed technique will enable accurate and efficient analyses of microscopic specimens that have a distinctive absorption or refractive index contrast in the SWIR range. 

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3. Multipolar Resonances in Electro‐Optic Metasurfaces with Moderate Refractive Index

   https://doi.org/10.1002/adpr.202500146  

   Babicheva, Viktoriia E; Rumi, Mariacristina (December 2025, Advanced Photonics Research)

   The electro‐optic (EO) effect is one of the physical mechanisms enabling the dynamic response of metasurfaces, which motivates the analysis of nanoantenna arrays integrated with EO materials. It was shown earlier that chalcophosphate Sn₂P₂S₆metasurfaces can enable significant shifts of multipolar resonances by enhancing the EO response near the Curie temperature. The present work explores how the refractive index of EO materials impacts resonance shifts in metasurfaces with multipolar resonances. It is numerically demonstrated that EO nanoantennas can support pronounced multipolar resonances despite their moderate refractive index, enabling strong light confinement and substantial EO tuning, and that multipolar components of even parity exhibit the highest sensitivity to variations in the refractive index of the nanoantennas. For moderate refractive indices varying from 2.3 to 3.0, it is found that, for a given resonance, the wavelength shift resulting from a refractive index change has a relatively weak dependence on the index itself. This suggests that the refractive index plays only a marginal role in enhancing the EO shift in active photonic devices, and instead, other considerations for material selection, such as the EO coefficient magnitude, the transparency window, and ease of processing, should be of primary concern. 

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4. Design and fabrication of robust hybrid photonic crystal cavities

   https://doi.org/10.1515/nanoph-2024-0500  

   Abulnaga, Alex; Karg, Sean; Mukherjee, Sounak; Gupta, Adbhut; Baldwin, Kirk W; Pfeiffer, Loren N; de_Leon, Nathalie P (November 2024, Nanophotonics)

   Abstract Heterogeneously integrated hybrid photonic crystal cavities enable strong light–matter interactions with solid state, optically addressable quantum memories. A key challenge to realizing high quality factor (Q) hybrid photonic crystals is the reduced index contrast on the substrate compared to suspended devices in air. This challenge is particularly acute for color centers in diamond because of diamond’s high refractive index, which leads to increased scattering loss into the substrate. Here, we develop a design methodology for hybrid photonic crystals utilizing a detailed understanding of substrate-mediated loss, which incorporates sensitivity to fabrication errors as a critical parameter. Using this methodology, we design robust, high-Q, GaAs-on-diamond photonic crystal cavities, and by optimizing our fabrication procedure, we experimentally realize cavities withQapproaching 30,000 at a resonance wavelength of 955 nm. 

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5. A Refractometer for Measuring Thermohaline Density Microstructure in the Ocean

   https://doi.org/10.1175/JTECH-D-24-0072.1  

   Kapit, Jason A; Farr, Norman E; Schmitt, Raymond W (September 2025, Journal of Atmospheric and Oceanic Technology)

   Here we report an optical sensor for measuring millimeter-scale thermohaline density variations in the ocean. The instrument is based on a fiber Fabry-Perot white light interferometer which can resolve the refractive index of water to better than 2 x 10⁻⁸within a sample volume smaller than 1 mm³at a sample rate of 500 Hz. This equates to detectable absolute salinity variations of 0.0001 g/kg, temperature variations smaller than 0.0007°C, and density variations of 0.00007 kg/m³. Data collected from laboratory characterization and a field deployment suggest the sensor could be useful as a gradiometer for measuring diapycnal mixing down to sub-millimeter scales. While obtaining high absolute accuracy in refractive index and density was not a primary consideration, the sensor was designed with such an eventual goal in mind, and various aspects of achieving it are discussed. 

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