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1. Disentangling the visual cues of an evolutionary trap for aquatic insects

   https://doi.org/10.1007/s10682-025-10378-9  

   Forgan, Nathan_W; Cohen_Suárez, Camila_M; Lovecky, Willow_S; Crumrine, Patrick_W; Robertson, Bruce_A; Haynes, Kyle_J (January 2026, Evolutionary Ecology)

   Abstract Aquatic insects use polarized light as a reliable visual cue for locating water surfaces given their need to locate sites for oviposition. However, many man-made surfaces polarize light more strongly than natural waterbodies creating an evolutionary trap in which many species preferentially lay their eggs on these polarizing artificial surfaces. Previous work has shown that the attractiveness of artificial surfaces to aquatic insects is diminished by adding non-polarizing gridlines to these surfaces. However, it is unknown how this mitigation affects aquatic insect preferences. We tested two alternative hypotheses about how aquatic insects judge the quality of potential oviposition sites. The visual averaging hypothesis states that insects judge the quality of a surface based on the percent area of the surface that is polarizing. An alternative hypothesis is that the quality of a polarizing surface is judged by the degree to which it is fragmented by non-polarizing elements. This experiment was conducted using oil tray traps as artificial polarizers whose percentage of polarizing area and the presence/absence of fragmentation was manipulated. Only Diptera were captured in sufficient numbers to test the hypotheses. Our findings for the dominant family in our captures, Dolichopodidae, were consistent with the visual averaging hypothesis – increasing the percent area that was non-polarizing significantly decreased captures, but the fragmentation of a polarizing surface had no significant effect on the number captured. For the other families of aquatic Diptera combined, however, there was a complex interactive effect of percent area of a surface that was polarizing and its fragmentation by non-polarizing gridlines. For the conservation of aquatic insects, these findings support the effectiveness of reducing the attractiveness of artificial polarizing surfaces such as solar panels by adding non-polarizing elements, but also show that for some aquatic insects, it is important to consider if the non-polarizing elements fragment the surface. 

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2. Optical Chirality Detection Using a Topological Insulator Transistor

   https://doi.org/10.1002/adom.202002210  

   Huang, Shouyuan; Xu, Xianfan (March 2021, Advanced Optical Materials)

   Abstract Optical chirality is an effective means in screening molecules and their enantiomers in bioengineering, and recently has garnered attention as an implementation of qubits in quantum information processing. The conventional detection of circularly polarized light (CPL) is based on phase retardation and polarization separation using multiple optical components. An intrinsic solid‐state chirality detection device would be favorable for easier integration and implementation. Optical spin injection to the spin‐momentum‐locked topological surface states of topological insulators (TIs) by circularly polarized light leads to a directional DC photocurrent and hence possible circular polarization detection. However, this DC photocurrent is also accompanied by other photo‐responses. Here, a photodetection strategy using a TI transistor which senses CPL without the use of any additional components is demonstrated, it achieves a uniform response over the entire device with a sensitivity ≈5.6%. The Stokes parameters can also be extracted by arithmetic operation of photocurrents obtained with different bias and gate for a complete characterization of a polarized light beam. Therefore, this method enables chirality detection and Stokes parameter analysis using a single device. The proposed miniaturized intrinsic chirality detectors facilitate polarimetry sensing in applications from circular dichroism spectroscopy to biomedical diagnosis. 

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3. Troubleshooting spectral artifacts from biplate retarders for reliable Stokes spectropolarimetry

   https://doi.org/10.1063/5.0160132  

   Lima, Ruan_L S; Araújo, Paulo T; Barbosa_Neto, Newton M (October 2023, Review of Scientific Instruments)

   Polarimetry is generally used to determine the polarization state of light beams in various research fields, such as biomedicine, astronomy, and materials science. In particular, the rotating quarter-wave plate polarimeter is an inexpensive and versatile option used in several single-wavelength applications to determine the four Stokes parameters. Extending this technique to broadband spectroscopic measurements is of great scientific interest since the information on light polarization is highly sensitive to anisotropic phenomena. However, the need for achromatic polarizing elements, especially quarter-wave plates, requires special attention in their modeling. In this study, we implemented a rotating retarder spectropolarimeter for broadband measurements using a commercially available quasi-achromatic biplate retarder over the visible range. Here, we present a comprehensive approach for troubleshooting this type of spectropolarimeter through the observation of artifacts stemming from the standard single-plate retarder model. Then, we derive a more suitable model for a quasi-achromatic retarder consisting of a biplate junction. This new biplate model requires knowledge of the intrinsic dispersive properties of the biplate, namely the equivalent retardance, fast axis tilt, and rotatory angle. Hence, in this study, we also show a self-consistent methodology to determine these biplate properties using the same polarimeter apparatus so that accurate Stokes parameters can be determined independently. Finally, the comparison of data generated with the standard single-plate and new biplate models shows a significant improvement in the measurement precision of the investigated polarization states, which confirms that remodeling the retarder for reliable spectropolarimetry is necessary. 

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4. Measuring linear birefringence via rotating-sample transmission Stokes spectropolarimetry

   https://doi.org/10.1364/AO.534443  

   Lima, Ruan_L_S; Silva, Eric_S; Araujo, Paulo_T; Barbosa_Neto, Newton_M (October 2024, Applied Optics)

   Linear birefringence is a fundamental property of optically anisotropic media, defined by the difference in refractive index experienced by light polarized along orthogonal directions. It is usually manifested in microscopically aligned molecular systems, where a preferential direction of light–matter interaction is created. For instance, the anisotropic structure of calcite crystal causes the famous double-refraction phenomenon. Another common example is commercial adhesive tapes, which are polymeric materials possessing birefringent properties due to their manufacturing processes. The intrinsic relation between birefringence and molecular alignment forges a new analytical route to study materials such as polymeric thin films. Therefore, the capacity of measuring linear birefringence and its fast axis is of paramount importance for the science of anisotropic molecular systems. In this contribution, a comprehensive approach to acquire linear birefringence using rotating-sample transmission Stokes spectropolarimetry is presented and applied to transparent adhesive tapes as a case study. The experimental setup comprises a thermal light source and a spectropolarimeter capable of determining wavelength distributions of Stokes parameters. The samples are carefully aligned in a rotating mount and subjected to a fixed broadband vertically polarized light beam. Then, the transmitted light is analyzed using a rotating retarder type of spectropolarimeter. Through systematic variation of the sample’s angular position, the Stokes parameters of transmitted light are measured for each transmitted wavelength as a function of the sample’s angular position. The linear retardance and fast axis direction relative to the tape’s long axis are then determined from the modulation of Stokes parameters over sample rotation. The model derivation, experimental procedure, and signal processing protocol are described in detail, and the approach is verified with a simple correlation between linear retardance and the number of stacked layers of tape. 

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5. Mueller matrix ellipsometer using dual continuously rotating anisotropic mirrors

   https://doi.org/10.1364/OL.398060  

   Ruder, Alexander; Wright, Brandon; Peev, Darin; Feder, Rene; Kilic, Ufuk; Hilfiker, Matthew; Schubert, Eva; Herzinger, Craig_M; Schubert, Mathias (June 2020, Optics Letters)

   We demonstrate calibration and operation of a single wavelength (660 nm) Mueller matrix ellipsometer in normal transmission configuration using dual continuously rotating anisotropic mirrors. The mirrors contain highly spatially coherent nanostructure slanted columnar titanium thin films deposited onto optically thick gold layers on glass substrates. Upon rotation around the mirror normal axis, sufficient modulation of the Stokes parameters of light reflected at oblique angle of incidence is achieved. Thereby, the mirrors can be used as a polarization state generator and polarization state analyzer in a generalized ellipsometry instrument. A Fourier expansion approach is found sufficient to render and calibrate the effects of the mirror rotations onto the polarized light train within the ellipsometer. The Mueller matrix elements of a set of anisotropic samples consisting of a linear polarizer and a linear retarder are measured and compared with model data, and very good agreement is observed. 

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