On-chip spatiotemporal optical vortex generation using an integrated metal-dielectric resonator

We theoretically demonstrate the possibility of generating a spatiotemporal optical vortex (STOV) beam in a dielectric slab waveguide. The STOV is generated upon reflection of a spatiotemporal optical pulse from an integrated metal-dielectric structure consisting of metal strips "buried" in the waveguide. For describing the interaction of the incident pulse with the integrated structure, we derive its "vectorial" spatiotemporal transfer function (TF) describing the transformation of the electromagnetic field components of the incident pulse. We show that if the TF of the structure corresponds to the TF of a spatiotemporal differentiator with a $\pi/2$ phase difference between the terms describing temporal and spatial differentiation, then the envelope of the reflected pulse will contain an STOV in all nonzero components of the electromagnetic field. The obtained theoretical results are in good agreement with the results of rigorous numerical simulation of the STOV generation using a three-strip metal-dielectric integrated structure. We believe that the presented results pave the way for the research and application of STOV beams in the on-chip geometry.Comment: 14 pages, 5 figure

Near-Field Diffraction from a Binary Microaxicon

We study binary axicons of period 4, 6, and 8 μm fabricated by photolithography with a 1 μm resolution, 500 nm depth, and 4 mm diameter. Near-field diffraction focal spots varying in diameter from 3.5λ to 4.5λ (for the axicon of period T=4 μm) and from 5λ to 8λ (for the axicon with T=8 μm) are experimentally found on the optical axis at a distance of up to 40 μm from the axicon for the wavelength λ=0.532 μm. The first focal spot is found at distance 2 μm (T=4 μm), with the period of the focal spots being 2 μm (T=4 μm) and 4 μm (T=8 μm). Diffraction of linearly polarized plane and diverging waves is simulated using FullWAVE (RSoft) and a proprietary program BOR-FDTD, which implement finite-difference schemes to solve three-dimensional Maxwell's equations in the Cartesian and cylindrical coordinates. The numerically simulated values for diameters of the near-field focal spots for the axicon of period T=4 μm are in good agreement with the experimental values

Multicenter prospective validation study for international chronic ocular graft-versus-host disease consensus diagnostic criteria

© 2022Purpose: To validate the international chronic ocular graft-versus-host disease (GVHD) diagnostic criteria (ICCGVHD) compared to the National Institute of Health diagnostic criteria 2014 (NIH2014) for chronic ocular GVHD. Methods: Between 2013 and 2019, the study enrolled 233 patients with or without chronic ocular GVHD combined with the presence or absence of systemic chronic GVHD in an internationally prospective multicenter and observational cohort from 9 institutions. All patients were evaluated for four clinical parameters of ICCGVHD. Results: The relation between the ICCGVHD score (0-11) and NIH2014 eye score (0–4) was relatively high (r = 0.708, 95% CI: 0.637–0.767, p < 0.001). The sensitivity and specificity of ICCGVHD for NIH 2014 for 233 patients were 94.3% (95% CI: 89.6%–98.1%) and 71.7% (95% CI: 63.0–79.5%), respectively (cutoff value of the ICCGVHD score = 6). The positive predictive value was 77.1% (95% CI: 71.1%–82.1%), and the negative predictive value was 87.0% (95% CI:81.6–92.5%). For the patients with systemic GVHD (n = 171), the sensitivity and specificity were 94.2% and 67.2%, respectively (ICCGVHD-score cutoff value = 6). By receiver operating characteristic (ROC) curve analysis, the area under the curve (AUC) was 0.903 (95% CI: 0.859–0.948). For patients without systemic GVHD (n = 62), the sensitivity and specificity were 100% and 76.7%, respectively (ICCGVHD-score cutoff value = 6). The AUC was 0.891 (95% CI 0.673–1.000). Conclusions: Good sensitivity, specificity, predictive value and correlation were found between ICCGVHD and NIH2014. ICCGVHD scores ≥6 can be useful to diagnose ocular GVHD with or without systemic GVHD for clinical research.N