Skyrmion engineering with origami.

Skyrmion structures play critical roles in solid-state systems involving electric, magnetic and optical fields. Previous approaches to the study of skyrmions have involved specific structures in magnetic materials, liquid crystals and polymers in addition to two-dimensional arrays used for electrical control. These methods have encountered limitations and constraints on both the microscopic and macroscopic scales related to the physical properties of materials.

Calibration for endoscopic 3D shape measurement with cone beam projection.

We demonstrate a calibration method for endoscopic three-dimensional shape measurement with cone beam projection. In this method, changes in the shape of the optical sectioning profiles are quantified and fitted while scanning a calibration board in the depth direction, using a cubic function. In accuracy tests using a flat plate and a ring reference gauge, the proposed method obtains an accuracy of 0.

Simultaneous detection of polarization states and wavefront by an angular variant micro-retarder-lens array.

We have demonstrated simultaneous detection of the polarization states and wavefront of light using a 7 × 7 array of angular variant micro-retarder-lenses. Manipulating the angular variant polarization with our optical element allows us to determine the two-dimensional distribution of polarization states. We have also proposed a calibration method for polarization measurements using our micro-retarder-lens array, allowing accurate detection of polarization states with an ellipticity of ± 0.

Megahertz detection of spectroscopic polarization by a time-encoded supercontinuum vector beam.

We demonstrated a 40-MHz detection of spectroscopic polarization by a supercontinuum vector beam with a wavelength-dependent polarization state. To achieve the high-repetition-rate measurement, we detected the rotation angle of polarization and the spectrum by measuring the temporal waveform using a photodetector after expanding the pulse duration of the supercontinuum vector beam. The spectrum of the supercontinuum vector beam was measured using a spectrometer.

Lensless single-fiber ghost imaging.

We demonstrate lensless single-fiber ghost imaging, which allows illumination and collection using a single optical fiber without a transmission-type system. Speckle patterns with relative coincidence degrees of 0.14 were formed by image reconstruction using improved differential ghost imaging.

Detection of birefringence singularity by supercontinuum vector beam.

We demonstrated detection of birefringence singularity on the space-variant retarder with an inhomogeneous birefringence distribution by supercontinuum vector beam. The birefringence measurement by supercontinuum vector beam analysis provides kinematics of a singularity point on the space-variant retarder. We conducted numerical calculations and experiments for proof of principle.

Silicon twisted cone structure produced by optical vortex pulse with structure evaluation by radiation hydrodynamic simulation.

We demonstrate a radiation hydrodynamic simulation of optical vortex pulse-ablated microcone structures on silicon (Si) substrates. Doughnut-shaped craters were formed by single pulse irradiation on the Si substrate, and a twisted cone structure with a height of 3.5 µm was created at the center of the irradiation spot by the circularly polarized optical vortex pulse.

Single-shot multispectral birefringence mapping by supercontinuum vector beams.

We demonstrated a single-shot, multispectral birefringence mapping by use of a supercontinuum (SC) vector beam. The vector beam, which was generated by a pair of axially symmetric wave plates, leads to angular-variant polarization modulation to divide birefringence properties of a sample substrate into Fourier space. This strategy allows multispectral birefringence mapping from a single-shot image captured by a multispectral imaging detector.

Demonstration of stimulated emission depletion phenomenon in luminescence of solid-state scintillator excited by soft X-rays.

Although imaging techniques using soft X-rays (SXs) are being developed as the available photon flux increases because of the continuing development of synchrotron light sources, it will be necessary to downsize the pixel size of the SX camera to produce finer SX images. Application of the stimulated emission depletion (STED) method to a scintillator plate followed by use of this plate as a sensor is one promising method to reduce the pixel size of SX cameras. A STED phenomenon occurred in the luminescence of a Ce-doped LuSiO crystal (Ce:LSO) excited using ultraviolet (UV) light when the scintillator was irradiated with azimuthally polarized laser light in the photon energy range from 1.

Three-dimensional measurement of an inner surface profile using a supercontinuum beam.

We demonstrate an inner surface profile measurement that has a smooth spatial distribution. A supercontinuum beam suppresses the speckle contrast to 22% and the standard deviation of the point cloud to 40%, compared to equivalent values obtained by use of a conventional green He-Ne laser at a wavelength of 543.5 nm.

Demonstration of a terahertz pure vector beam by tailoring geometric phase.

We demonstrate the creation of a vector beam by tailoring geometric phase of left- and right- circularly polarized beams. Such a vector beam with a uniform phase has not been demonstrated before because a vortex phase remains in the beam. We focus on vortex phase cancellation to generate vector beams in terahertz regions, and measure the geometric phase of the beam and its spatial distribution of polarization.

Determination of the polarization states of an arbitrary polarized terahertz beam: vectorial vortex analysis.

Vectorial vortex analysis is used to determine the polarization states of an arbitrarily polarized terahertz (0.1-1.6 THz) beam using THz achromatic axially symmetric wave (TAS) plates, which have a phase retardance of Δ = 163° and are made of polytetrafluorethylene.

Generation of achromatic, uniform-phase, radially polarized beams.

Axially symmetric half-wave plates have been used to generate radially polarized beams that have constant phase in the plane transverse to propagation. However, since the retardance introduced by these waveplates depends on the wavelength, it is difficult to generate radially polarized beams achromatically. This paper describes a technique suitable for the generation of achromatic, radially polarized beams with uniform phase.

Achromatic axially symmetric wave plate.

An achromatic axially symmetric wave plate (AAS-WP) is proposed that is based on Fresnel reflections. The wave plate does not introduce spatial dispersion. It provides retardation in the wavelength domain with an axially symmetric azimuthal angle.