Differentiable design of progressive-addition lens using NURBS surface.

Presbyopia is an age-related condition that gradually reduces the eye's ability to focus on nearby objects, affecting over a billion people globally. The progressive-addition lens (PAL), commonly used for presbyopia correction, struggles to eliminate inherent astigmatism in the lateral areas of the progressive corridor. In this paper, we propose an efficient method for designing PAL using a differentiable optimization approach based on non-uniform rational B-spline (NURBS) surface, with an initial estimate derived through a modified variational-difference numerical method.

Differentiable design of continuous phase plates using multi-level B-splines with smoothness constraints.

Continuous phase plates (CPPs) are crucial optical elements in inertial confinement fusion facilities for laser beam smoothing. Traditional design methods based on Gerchberg-Saxton (GS) algorithms face two fundamental limitations: lack of direct control over phase smoothness and susceptibility to local optima convergence. We propose a CPP design method enforcing phase smoothness by modeling the phase distribution using multi-level B-splines and integrating the curvature and power spectral density (PSD) of the surface as the regularization terms.

Differentiable design of freeform lenses for partially coherent beam shaping.

Partially coherent beams (PCBs), with unique properties such as reduced speckles and self-reconstruction, hold great promise for optical communication, particle trapping, and laser material processing. However, designing optical elements for shaping PCBs remains a significant challenge. We present a differentiable design method of freeform lenses for shaping PCBs.

Differentiable optimization of multiple freeform lenses for high-performance tilted illumination.

We present an optimization framework for designing multiple freeform lenses to achieve high-performance oblique illumination. The optimization process involves two steps: optimizing the irradiance distribution on an intermediate plane and fine-tuning the surface parameters to achieve the desired tilted target irradiance distribution. The framework could be used to design freeform illumination systems with an arbitrary number of lenses without significantly increasing the computational resource requirements.

Exploring the Fractional Quantum Anomalous Hall Effect in Moiré Materials: Advances and Future Perspectives.

The search for anyons, quasiparticles with fractional charge and exotic exchange statistics, has inspired the research of condensed matter physics for decades. Moiré materials, as superlattice systems characterized by tunable isolated topological flat bands, represent a vast material library, with the ability to adjust properties via various tuning knobs, and show particular suitability for investigating the physics of anyons. In the study of Hall effects, Moiré systems offer a distinctive platform to achieve various Hall effects such as the valley Hall effect, nonlinear Hall effect, quantum anomalous Hall effect, and fractional quantum anomalous Hall effect (FQAHE).

Differentiable design of freeform diffractive optical elements for beam shaping by representing phase distribution using multi-level B-splines.

The generation of a specific laser beam profile on the work surface is key to various laser beam shaping tasks, relying heavily on diffractive optical elements (DOEs). Most beam-shaping DOEs are designed using iterative Fourier transform algorithms (IFTAs), which generally have slow convergence and prone to stagnate at local minima. Moreover, the microreliefs generated by IFTAs tend to be irregular, complicating manufacturing and causing uncontrolled scattering of light.

Topological Hall Effect in Thin Films of an Antiferromagnetic Weyl Semimetal Integrated on Si.

Since the large room-temperature anomalous Hall effect was discovered in noncollinear antiferromagnets, MnSn has received immense research interest as it exhibits abundant exotic physical properties including Weyl points and enormous potential for antiferromagnetic spintronic device applications. In this work, we report the emergence of the topological Hall effect in MnSn films grown on Si that is the workhorse for the modern highly integrated information technology. Importantly, through a series of systematic comparative experiments, the intriguing topological Hall effect phenomenon related to the appearance of the noncoplanar chiral spin structure is found to be induced by the MnSn/SiO interface.

Room-temperature magnetoresistance in an all-antiferromagnetic tunnel junction.

Antiferromagnetic spintronics is a rapidly growing field in condensed-matter physics and information technology with potential applications for high-density and ultrafast information devices. However, the practical application of these devices has been largely limited by small electrical outputs at room temperature. Here we describe a room-temperature exchange-bias effect between a collinear antiferromagnet, MnPt, and a non-collinear antiferromagnet, MnPt, which together are similar to a ferromagnet-antiferromagnet exchange-bias system.

Chemical Potential Switching of the Anomalous Hall Effect in an Ultrathin Noncollinear Antiferromagnetic Metal.

The discovery of the anomalous Hall effect in noncollinear antiferromagnetic metals represents one of the most important breakthroughs for the emergent antiferromagnetic spintronics. The tuning of chemical potential has been an important theoretical approach to varying the anomalous Hall conductivity, but the direct experimental demonstration has been challenging owing to the large carrier density of metals. In this work, an ultrathin noncollinear antiferromagnetic Mn Ge film is fabricated and its carrier density is modulated by ionic liquid gating.

Optical design and pupil swim analysis of a compact, large EPD and immersive VR head mounted display.

Virtual reality head-mounted displays (VR-HMDs) are crucial to Metaverse which appears to be one of the most popular terms to have been adopted over the internet recently. It provides basic infrastructure and entrance to cater for the next evolution of social interaction, and it has already been widely used in many fields. The VR-HMDs with traditional aspherical or Fresnel optics are not suitable for long-term usage because of the image quality, system size, and weight.

Antiferromagnetism in Ni-Based Superconductors.

Due to the lack of any magnetic order down to 1.7 K in the parent bulk compound NdNiO , the recently discovered 9-15 K superconductivity in the infinite-layer Nd Sr NiO thin films has provided an exciting playground for unearthing new superconductivity mechanisms. Herein, the successful synthesis of a series of superconducting Nd Sr NiO thin films ranging from 8 to 40 nm is reported.

Freeform beam splitting system design for generating an array of identical sub-beams.

Laser beam splitting by freeform optics is promising but less studied. Instead of directly forming a target spot array, we propose to first convert the input beam into a closely connected Gaussian sub-beam array. All the Gaussian sub-beams have the same optical field distributions which thus can produce identical discrete spots on the target plane.

Designing double freeform surfaces for large ray bending irradiance tailoring of extended LED sources.

Many illumination applications require redistributing the irradiance distributions of LED sources with large ray bending. The problem becomes even more challenging for a compact design where the LED size is no longer ignorable. We tackle this problem by simultaneously designing two freeform optical surfaces.

Compact integrator design for short-distance sharp and unconventional geometric irradiance tailoring.

A compact microlens array (MLA) integral homogenizer composed of a projection MLA, a condenser MLA, and a subimage array mask based on Kohler illumination is presented herein. By adopting the optimal design of an aspheric projection sublens, a short-distance integrator for unconventional geometric irradiance tailoring can be acquired. Compared with the traditional integrator, the integral lens is removed in the proposed integrator.

Transferring freeform lens design into phase retrieval through intermediate irradiance transport.

Freeform lens design for the prescribed irradiance without thin element and paraxial approximations is very complicated. We propose to transport a point source irradiance before the required freeform lens into an intermediate irradiance estimate next to the lens. In this way, the complicated freeform lens design problem could be transferred into a simpler problem of retrieving the phase from the intermediate and target irradiances.

Iterative wavefront tailoring to simplify freeform optical design for prescribed irradiance.

The direct formulation of a freeform optical surface for producing a prescribed irradiance from a point source is very complicated. Instead of directly determining the freeform optical surfaces, we derive a general equation of a parameterized outgoing wavefront, regardless of the structure of the optical element. A separate process is employed to construct the freeform optics following the solution of the wavefront equation.

Simplified freeform optics design for complicated laser beam shaping.

Control of the optical fields of laser beams, i.e., laser beam shaping, is of great importance to many laser applications.

Freeform illumination optics construction following an optimal transport map.

We present a modified optimal transport (OT) ray-mapping approach for designing freeform illumination optics. After mapping the source intensity into a virtual irradiance distribution under stereographic projection, we employ an advanced OT map computation method with the ability to tackle nonstandard boundary conditions. Following the computed map, we construct the freeform optical surface directly from normal vectors by requiring that the chord between two adjacent points is perpendicular to the average of the two normal vectors at these two points and enforcing this relationship with a least squares method.

Composite method for precise freeform optical beam shaping.

We present a composite freeform surface construction method for creating a high-accuracy irradiance distribution from a given incident beam under the influence of diffraction. The main idea is that we first determine a fully continuous freeform surface estimate by solving a standard Monge-Ampère equation and then refine it using an iterative Fourier-transform algorithm associated with over-compensation. Although this method can only be implemented in the paraxial approximation, it can significantly simplify the design and is applicable to many examples that fulfill this restriction.

Creating unconventional geometric beams with large depth of field using double freeform-surface optics.

We consider here creation of an unconventional flattop beam with a large depth of field by employing double freeform optical surfaces. The output beam is designed with continuous variations from the flattop to almost zero near the edges to resist the influence of diffraction on its propagation. We solve this challenging problem by naturally incorporating an optimal transport map computation scheme for unconventional boundary conditions with a simultaneous point-by-point double surface construction procedure.

Tailoring freeform illumination optics in a double-pole coordinate system.

We have developed a new method to design freeform illumination optics by introducing a double-pole coordinate system in ray mapping. This method establishes a much more accurate ray mapping by moving the two poles of the spherical coordinate system to the southernmost point of the sphere and overlapping them together. It can reduce surface error and improve illumination uniformity significantly.