Blazed gratings are widely employed in polarization spectral imaging technology. This work systematically investigates the polarization mechanisms of low blaze angle ruled gratings in the -1st order Littrow mounting and fabricated high-efficiency polarization-independent low blaze angle ruled grating samples. We conducted a study through rigorous coupled-wave analysis (RCWA), the Drude-Lorentz dispersion model for aluminum (Al), and experimental validation. Simulation results show that a grating of 600 gr/mm groove density and a blaze angle of 2° achieves TE and TM efficiencies above 80%, and a polarization degree (PD) value under 0.6% at a wavelength of 116 nm, a low blaze angle plays a dominant role in suppressing PD. The simulated TE and TM efficiencies and PD of grating samples show good agreement with measurements in the 260-1000 nm range, validating the modeling approach and enabling reliable prediction that at its blaze wavelength of 123 nm, Grating-IV maintains TE and TM efficiencies above 85% with an extremely low PD of about 0.16%. Simulations and experiments confirm that the high groove density and low blaze angle gratings in the -1st order Littrow mounting achieve both high diffraction efficiency and polarization independence, providing practical guidance for grating design.
We explain the wideband mechanism of superwavelength gratings (SWGs) with low blaze angles based on electromagnetic field theory. The study shows that the grating scale corresponding to the blaze wavelength of a triangular-grooved metallic grating shifts to the superwavelength direction as the blaze angle decreases. At the blaze wavelength, the SWG with low blaze angle suppresses the polarization effect and achieves near-perfect blazing of TE- and TM-polarised light. On the other hand, it eliminates the higher-order Rayleigh anomalies through the compensation effect, thereby achieving a wideband output with polarization insensitivity. Based on the obtained mechanism, an Al SWG with a blaze angle of 3° is designed, which has an unpolarized efficiency (-1st order) of more than 40% (70%) in the 900-2500 nm (1030-1900 nm) band, with a maximum efficiency of 94.59%. In addition, the comparison of angular selectivity and wavelength selectivity demonstrates that the Al SWG is superior to the Al near-wavelength grating in terms of bandwidth, diffraction efficiency, and polarization effect suppression. These results can be used to guide the design and fabrication of wideband metallic gratings in different wavelength bands.
Maintaining the highest quality and output of photon science in the VUV-, EUV-, soft-, and tender-x-ray energy ranges requires high-quality blazed profile gratings. Currently, their availability is critical due to technological challenges and limited manufacturing resources. In this work, we show the developed method for manufacturing blazed gratings relevant for synchrotron-based science by means of electron-beam lithography (EBL). We investigate different parameters influencing the optical performance of blazed profile gratings and develop a robust process for the manufacturing of high-quality blazed gratings using polymethyl methacrylate as a high resolution positive tone resist and ion beam etching. Finally, we demonstrate excellent agreement in efficiency between the produced EBL grating and the theoretical prediction.
A nano-inscribing technique was tested as a method of cost-effective replication of blazed diffraction gratings for x-rays. A saw-tooth mold for the nano-inscribing was fabricated by a double-replication process from a master blazed grating. The nano-inscribing was performed using a UV-curable resist of low viscosity to provide a small thickness of the resist replicas, required for a following transfer process. The nano-inscribing process was optimized to minimize surface relaxation and preserve the saw-tooth shape of the grooves, required for high diffraction efficiency. The quality of the replica gratings was evaluated via diffraction efficiency simulations. The simulations demonstrated that near theoretical efficiency can be achieved for the x-ray gratings made by the nano-inscribing approach.
Broadband gratings are fundamental optical components in broadband spectral instruments. Herein, the complexity and cost of fabrication methods are addressed by zoned blazed broadband grating fabrication via mosaicking technology. A blaze angle calculation method and zoned grating structural parameters are established and designed. Steps for 5D mosaicking error separation and correction are established via analysis and simulations. Accordingly, a highly stable mosaicking-error-adjustment device made of special materials is designed, and a grating is fabricated. The grating wavelength range is 200-1100 nm, the diffraction wavefront is better than λ/4, and the diffraction efficiency exceeds 30% in 90% of the blaze band.
We propose and demonstrate what we believe to be a new method for femtosecond laser multi-foci parallel plane-by-plane inscription of fiber Bragg grating. The method involves diffracting a femtosecond laser into multiple beams by superimposing multiple blazed grating phase masks with different parameters on the spatial light modulator. This method enables the production of multiple foci with controllable positions and single-pulse energies within the fiber core. Since the blazed grating phase masks do not disrupt the phase of the diffracted beams, combined with diaphragm beam shaping, each focus can induce a refractive index modulation plane of the same size on the core through the coating. Based on this method, we fabricated a high-reflectivity fiber Bragg grating in 20/400 µm double-clad passive fiber, achieving reflectivity greater than 99.9% and insertion loss less than 0.08 dB. The fabrication process involves superimposing two blazed grating phase masks, which generate two foci separated by 13.58 µm and aligned along the radial direction of the fiber. These two foci enable the concurrent fabrication of two connected refractive index modulation planes, which are then stacked into a single FBG period through a single scan. Compared to the conventional plane-by-plane inscribed fiber Bragg grating, this method can significantly reduce fabrication time.
The universal approach was originally developed to design wideband multilayer coated blazed gratings operating in the tender X-ray region (E = 2-3 keV), realizing different diffraction geometries including constant incidence angle, constant Cff-factor, and constant deviation angle, while retaining high diffraction efficiency in a wide spectral range.The designed gratings coated by depth-graded Cr/C multilayer structures and operating in the -1st diffraction order are demonstrated to provide the constant factor Cff = 2.52 or the constant deviation angle ψ = 4.75° with the diffraction efficiency of 29% ± 2% or 17.5% ± 1.5%, respectively, throughout the 2-3 keV spectral range.
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Macroscopic substrate surface errors and microscopic groove parameters influence the optical performance of curved diffractive microstructures. However, existing profile measurement techniques face a trade-off between large-area coverage and high resolution, which limits the ability of conventional two-dimensional (2D) line-profile methods to capture the global grating morphology. To address existing limitations, this study proposes a three-dimensional (3D) profile characterization method for curved gratings across macro- and micro-scales. Seamless reconstruction of full-aperture 3D topography with submicron-scale features was achieved using laser scanning confocal microscopy-based stitching measurements. Preprocessing for feature extraction was then performed using frequency-domain separation and the iterative closest point algorithm. The 2D Gabor filter bank, traditionally used for image texture feature extraction, was extended to 3D space to precisely characterize the period distribution of the microstructures. When combined with local planar least-squares fitting, the method enables precise characterization of the 3D spatial distribution of the grating blaze angle. Experimental results demonstrate close agreement between 3D and 2D characterization, with deviations below 0.01 µm in mean period and 0.05° in mean blaze angle, confirming the accuracy and reliability of the method. This study overcomes the limitations of conventional 2D line-profile analysis by enabling high-precision, cross-scale 3D global characterization of curved diffractive microstructures, supporting process optimization and quality control in advanced optical manufacturing.
Brazilian Jiu Jitsu is a combat sport discipline characterized by high situational complexity. No studies in the literature provide a systematic scientific foundation for the comparison between traditional teaching methodologies and the ecological-dynamical approach. The aim of this study is to compare the effectiveness of two training approaches on the following parameters: Rate of Force Development, muscular reactivity, and perception of psychophysical distress. Sixty amateur and semi-professional athletes were equally divided into an experimental group and a control group. For the pre- and post-intervention assessments, the following tests were used: the Isometric Mid-Thigh Pull with a force platform for RFD; the Blaze Pod Reaction Speed test with Blaze Pods for reactivity; and ad hoc questionnaires to collect data on distress perception. The mixed 2 × 2 ANOVA showed that peak RFD increased by 15% in the experimental group compared with 5% in the control group (p = 0.020). Reaction times, also analyzed through mixed ANOVA, decreased by 15% in the experimental group compared with 7% in the control group (p = 0.007). Only the experimental group showed a significant reduction in perceived distress (Wilcoxon: Z = -4.10, p < 0.001). The post-intervention comparison between groups using the Mann-Whitney test revealed a significant difference in favor of the experimental group (U = 320.0, p =0.004). The results indicate that an approach based on the ecological-dynamical framework leads to greater improvements in explosive capacity, reactivity, and distress management in Brazilian Jiu Jitsu athletes compared with the traditional method.
Dielectric phase-change metasurfaces enable programmable light control and show great application potential in optoelectronics. However, current technologies are limited by challenges in achieving high-uniformity, high-precision fabrication over large areas, as well as selective phase-state modulation of individual meta-atoms. To address these challenges, a femtosecond (fs)-laser phase-modulated non-diffracting-beam lithography (PNDL) technique is proposed. By superimposing axicon and blazed grating phases, the fs-laser beam is shaped into a quasi-Bessel non-diffracting-beam with a depth of focus over 10 times greater than that of a tightly focused Gaussian beam, thereby reducing the need for refocusing and minimizing focal drift. The dynamic beam deflection during fabrication can be controlled with 7 nm precision. The voxel metasurfaces composed of phase-change regions are then chemically processed to achieve maskless lithography. PNDL is used to fabricate a tunable Ge2Sb2Te5 metasurface with a structural feature size of 9 nm. Furthermore, multifunctional programmable photonic logic devices are fabricated and modulated, demonstrating high-precision capabilities. This approach provides a novel paradigm for active metasurface fabrication and modulation, laying the foundation for next-generation photonic devices.
Pharmacy education stands on unstable ground; overloaded curricula, eroding professional identity, and widening gaps between training and practice signal a system under pressure. Though other health professions are moving toward coordinated, competency-based transformation, pharmacy education risks falling behind. Drawing on recent stakeholder-informed studies and international precedents in medical and veterinary education, this commentary proposes Competency-Based Pharmacy Education (CBPE) not as reform but as essential infrastructure, a levee that must be constructed before pharmacy education is consumed by a flood of diminishing returns. Adapting the "escape fire" metaphor applied in medicine, we argue that pharmacy's crisis is not a sudden blaze but rapidly rising waters. In response, CBPE must serve as the levee: a deliberate, system-level structure grounded in Van Melle's core components framework. These 5 components (outcome competencies, sequenced progression, tailored experiences, competency-focused instruction, and programmatic assessment) form a resilient system that addresses pharmacy's most urgent vulnerabilities. Though early adopter programs are piloting elements of CBPE, true transformation requires national coordination. Fragmented efforts will not withstand structural erosion. This commentary issues a collective call to action for national alignment, collective investment, and pharmacy professional organization leadership. The evidence is clear. The stakes are existential. Additionally, the blueprint is already in our hands. CBPE is not a theory; it is the structure pharmacy must build together now, before the waters rise further.
Plasmonic gratings are versatile platforms for manipulating light-matter interactions; however, common unit-cell geometries, such as rectangular, sinusoidal, triangular, or blazed profiles, offer limited field enhancement and constrain further performance improvements. This paper reports a centimeter-scale plasmonic grating decorated with nanodendrites on the ridge sidewalls that enables strong near-field coupling and narrow resonance for ultrasensitive sensing. The structure was fabricated by interference lithography, where an in-plane interference pattern and an out-of-plane standing wave define double-nested unit cells. The subwavelength dendritic features promote strong near-field coupling and induce plasmon hybridization under perpendicular (x) polarization, whereas Rayleigh anomalies (RAs) with enhanced reflectance dominate under parallel (y) polarization. Dispersion analysis reveals a linear angle-dependent dispersion of the RA modes in contrast to the weak dispersion of the hybridized plasmon modes. A sharp, high-contrast RA resonance with enhanced reflection was achieved in high-index media, yielding a sensitivity of 510 nm/RIU and a figure of merit of 28.3 RIU-1 for plasmonic sensing.
Spectral information is essential in microscopy, yet many multispectral imaging solutions require increased optical complexity or restrict the spectrum to a few discrete bands. In this work we introduce the Terrace grating optics family: flat, 3D-printable elements that provide continuous spectral encoding, as a plug-and-play add-on component to standard microscopes. The Terrace design preserves the illumination path in widefield operation and integrates trivially with other microscopy phase masks. We introduce two variants: a Single-order Terrace that concentrates energy into one diffraction order for high signal-to-noise ratio, and a Dual-order Terrace that adds a wavelength-independent reference spot, enabling robust color decoding. Using a Fourier-optics model, we show that the wavelength displacement is linearly controlled by the Terrace step-width and refractive-index mismatch. We validate the approach in two settings: snapshot decoding of four-color mRNA barcodes and multicolor NeuroPAL worm imaging with a single camera exposure and instantaneous color readout. Furthermore, we demonstrate continuous spectral and depth encoding masks yielding simultaneous depth and color readout via PSF shape, which remains compact and efficient. Terrace gratings thus offer a practical alternative to prisms and blazed gratings, enabling continuous multispectral encoding and straightforward integration with conventional microscopes.
Augmented, virtual, and mixed reality devices increasingly rely on compact and efficient optical elements to guide and shape light into the user's eye. A key enabling technology for these devices is the use of surface relief gratings (SRGs) as optical in- and out-couplers within diffractive optical waveguides. A critical performance requirement is achieving uniform illumination of the eye-box, which ensures image clarity and consistency across the viewing area. To manufacture such high-performance SRGs, nanoimprint lithography (NIL) combined with direct etching techniques has proven effective. However, nanoimprint methods require the prior fabrication of a master stamp, which is a highly precise template that defines the nanoscale surface features to be replicated during the NIL process. This work demonstrates the nanopatterning capabilities of slanted and blazed SRGs in terms of sidewall angle, modulation of pitch and critical dimension, continuous depth variation and shape fidelity control by using advanced electron beam lithography and reactive ion beam trimming etching techniques.
We present a light-driven inching random laser composed of a liquid crystal elastomer body and a random lasing tip region. Under optical illumination, the composite random laser undergoes bending deformation, enabling a remote-controlled motion on flat and blazed grating surfaces. The inching random laser is optically guided to a designated target position, where the integrated random-lasing tip generates emission characterized by a bandwidth collapse and a distinct lasing threshold. The light-driven inching random laser offers a promising platform for delivering intense optical signals at a desired location.
EDITORIAL: "To eyelids in the Sepulchre-/ How dumb the Dancer lies-/ While Color's Revelations break-/ And blaze-the Butterflies!" A renowned American poet, Emily Dickinson's poem vividly mirrors the journey of women's growth: No matter how many hardships they encounter in their development or constraints they face, they will eventually break free from their "cocoons" and transform into colorful butterflies radiating "light". In this issue of "Light People", Professor Siying Peng is invited to share how the optical properties of butterfly wings have inspired her metamorphosis in the field of photonics.
In 1910, the U.S. federal government began an official policy of suppressing wildfires. Decades later it became understood that the giant sequoia, the world's most massive tree, is serotinous and depends upon fire to effectively reproduce. For a century, fire was almost completely excluded from giant sequoia groves, until a series of lightning fires over the past decade. After these fires, U.S. land managers hypothesized that the blazes had caused unprecedented levels of high-severity fire due to a century of fire suppression and fuel accumulation. Based on this assumption, U.S. legislation is now proposed to override environmental laws to allow logging in all giant sequoia groves on federal public lands, including in Wilderness Areas and national parks, in the name of wildfire prevention. In addition, lower-severity prescribed fires are now being implemented as a means to prevent and suppress mixed-severity wildfires, based on the assumption that high initial post-burn sequoia seedling densities after prescribed fire will translate to relatively high densities in later years. I investigated the effects of wildfire suppression in giant sequoia groves using GIS data of wildfire perimeters dating back to 1910, fire severity data from 2012 to present, and a government prescribed fire and sequoia regeneration dataset. I found fire of all severities since 1910 is below frequencies that occurred before fire suppression. I found no correlation between time-since-fire and the percentage of area burned comprised by high-severity fire in giant sequoia groves. Further, I found no correlation between initial (1 year post-burn) sequoia seedling densities and densities at 10 years following prescribed fire. The percentage of all plots lacking any sequoia regeneration after prescribed fire increased significantly over time. Only 23% of prescribed fire plots lacked sequoia regeneration at 1 year post-burn, while 82% of prescribed fire plots lacked sequoia regeneration at 20 years post-burn.
Immersed reflection gratings improve spectral resolving power by enabling diffraction within a high refractive index medium. This principle has been widely adopted to make grating spectrometers more compact. Conventional immersed gratings have blazed profiles which typically show the highest efficiency for one main design wavelength. In addition, the blazed profiles tend to cause significant polarization sensitivity. In this work, we propose an alternative approach for designing an immersed grating composed of sub-wavelength structures, designed to increase diffraction efficiency and reduce polarization dependence. For a theoretical demonstration, a reflective metagrating immersed in silicon is optimized over the short-wave infrared band-3 (SWIR-3, here 2.304 μm-2.405 μm), targeting the same diffraction angles as the immersion grating used in the Sentinel-5 Earth observation mission. The structure is optimized using a modified Covariance Matrix Adaptation Evolution Strategy (CMA-ES). The optimized immersed metagrating achieves an average efficiency of (over the SWIR-3 band) ∼78%, compared to ∼62% for the conventional immersed blazed grating, and reduces polarization sensitivity from roughly ∼15% to ∼5%. A manufacturing tolerance analysis is also conducted to evaluate the design's performance under systematic manufacturing errors, which revealed a degradation of ∼10% efficiency at feature size errors of ±25 nm and almost negligible effect on the efficiency at -10 nm and of ∼5% at +10 nm.