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Linearly polarized orbital angular momentum-carrying hard X-ray beams are induced using spiral Fresnel zone plates. By sending the hard X-ray beams to disordered enantiopure molecular complexes, the helicity-dependent and chiral-sensitive signal is obtained.
Coherent multi-octave mid-infrared waveforms are created and manipulated by cascaded intrapulse difference-frequency generation, demonstrating absolute phase control, and adding to the growing arsenal of techniques for arbitrary light-wave control.
The ability to create complex three-dimensional structures of light has reached new heights with the experimental observation of two distinct kinds of toroidal pulses, the optical analogue of smoke rings.
Ferroelectric domain switching controlled by electrical pulses provides a controllable means to tune the refractive index of BaTiO3 thin films. Now, a device based on this material is presented that is capable of implementing low-power, high-speed and CMOS-compatible programmable phase shifters in silicon photonic chips.
One hundred years ago, in 1922, Léon Brillouin discovered the scattering of light by sound waves. Within an optical fibre, Brillouin scattering may be used to create narrow-linewidth filters and spectrometers. A twisted optical fibre is now used to reduce these linewidths by over an order of magnitude, down to the sub-MHz level.
Strained NbOI2 flakes with a thickness of 20 nm exhibit a record SHG absolute conversion efficiency of >0.2% and an effective bulk-like nonlinear susceptibility of 1.1 × 10−9 m V−1 at the fundamental wavelength of 1,050 nm. The spatial profile of the polarized second-harmonic generation response can be tuned by the fundamental wavelength.
Asymmetric parametric generation of light in nonlinear metasurfaces is enabled by nonlinear dielectric resonators in translucent metasurfaces. Upon infrared illumination, different and independent visible light images are detected for ‘forwards’ versus ‘backwards’ operation.
Giant effective photon–photon interactions are achieved by hybridizing light with excitons in an InGaAs-based quantum well micropillar cavity. Cross-phase modulation of up to 3 mrad per polariton is observed at the laser intensity below the single-photon level.
Tunable sub-megahertz spectral features are demonstrated without resonators. The approach, which exploits gain-enhanced polarization pulling in a twisted birefringent medium, may be useful in applications such as microwave photonic filters, slow and fast light, and optical sensing.
High-harmonics spectroscopy reveals the closure of the bandgap between adjacent conduction bands in solids driven by high-intensity laser fields, providing insight into light-driven modifications of band structures
The strongly temperature-dependent band-edge absorption from gallium arsenide enables an optical thermometer with nanokelvin temperature resolution and microscale spatial resolution.
Researchers demonstrate a persistent spin helix in an organic–inorganic hybrid ferroelectric halide perovskite whose layered nature makes it intrinsically like a quantum well. They demonstrate a switchable spin-polarized band structure via an intrinsic ferroelectric field.