Polarization-independent highly efficient generation of Airy optical beams with dielectric metasurfaces

Airy optical beams have emerged to hold enormous theoretical and experimental research interest due to their outstanding characteristics.Conventional approaches suffer from bulky and costly systems,as well as poor phase discretization.The newly developed metasurface-based Airy beam generators have constraints of polarization dependence or limited generation efficiency.Here,we experimentally demonstrate a polarization-independent silicon dielectric metasurface for generation of high-efficiency Airy optical beams.In our implementation,rather than synchronous manipulation of the amplitude and phase by plasmonic or Huygens’metasurfaces,we employ and impose a 3/2 phase-only manipulation to the dielectric metasurface,consisting of an array of silicon nanopillars with an optimized transmission efficiency as high as 97%.The resultant Airy optical beams possess extraordinarily large deflection angles and relatively narrow beam widths.Our validated scheme will open up a fascinating doorway to broaden the application scenarios of Airy optical beams on ultracompact photonic platforms.

Y_(3)Al_(5)O_(12):Ce^(3+) fluorescent ceramic for optical data storage

A kind of optical data storage medium based on electron-trapping materials,Y_(3)Al_(5)O_(12):Ce^(3+)fluorescent ceramic,was developed by vacuum sintering technology.The medium shows sufficiently deep traps[1.67 and 0.77 eV].The properties of trap levels were researched by thermoluminescence curves,and the optical storage mechanism based on Ce^(3+)ion doping was proposed.More importantly,the data can be written-in by 254 nm UV light,and readout by heating[300°C].This work expands the application fields of fluorescent ceramics,and it is expected to promote the development of electron-trapping materials.

Linear variable filters fabricated by ion beam etching with triangle-shaped mask and normal film coating technique

In this Letter, we propose a method of fabricating linear variable filters by ion beam etching with masking mechanisms. A triangle-shaped mask is designed and set between the ion source and sample. During the ion etching,the sample is moved back and forth repeatedly with a constant velocity for the purpose of obtaining the linearly varied thickness of the cavity. Combined with ion beam assistant thermal oxidative electron beam evaporation deposition technology, we finish the fabrication of linear variable filters, whose filtering range is from 500 to 580 nm. The measured results indicate that the transmittance and bandwidth at the peak wavelength are around 40% and 3 nm.

Super-long longitudinal magnetization needle generated by focusing an azimuthally polarized and phasemodulated beam

Based on the inverse Faraday effect, a super-long longitudinal magnetization needle can be induced by a trans- versely polarized needle-shaped electric field. This needle-shaped electric field can be obtained in the focal vol- ume of the objective by focusing an azimuthally polarized vortex beam that is modulated both radially and azimuthally by a specifically designed annular phase filter. The numerical calculation shows that the full widths at half-maximums in longitudinal direction and in transverse direction of the magnetization needle are 282 and 0.27λ. The corresponding needle aspect ratio of 103 is more than ten times larger than that of the magnetization needle fabricated by electron beam lithography.

Low-noise InGaAs/InP single-photon detector with widely tunable repetition rates

InGaAs/InP avalanche photodiodes typically work in the gated Geiger mode to achieve near-infrared singlephoton detection. By using ultrashort gates and combining with the robust spike-canceling technique that consists of the capacitance-balancing and low-pass filtering technique, we demonstrate an InGaAs/InP single-photon detector(SPD) with widely tunable repetition rates in this paper. The operation frequency could be tuned conveniently from 100 MHz to 1.25 GHz with the SPD's performance measured to maintain good performance, making it quite suitable for quantum key distribution, laser ranging, and optical time domain reflectometry. Furthermore,the SPD exhibited extremely low-noise characteristics. The detection efficiency of this SPD could reach 20% with the dark count rate of 2.5 × 10^(-6)∕gate and after-pulse probability of 4.1% at 1 GHz.

Fast dual-beam alignment method for stimulated emission depletion microscopy using aggregation-induced emission dye resin

A stimulated emission depletion is capable of breaking the diffraction limit by exciting fluorescent molecules with a solid Gaussian beam and quenching the excited molecules with another donut beam through stimulated emission.The coincidence degree of these two beams in three dimensions will significantly influence the spatial resolution of the microscope.However,the conventional alignment approach based on raster scanning of gold nanoparticles by the two laser beams separately suffers from a mismatch between fluorescence and scattering modes.To circumvent the above problems,we demonstrate a fast alignment design by scanning the second beam over the fabricated sample,which is made of aggregation-induced emission(AIE)dye resin.The relative positions of solid and donut laser beams can be represented by the fluorescent AIE from the labeled spots in the dye resin.This design achieves ultra-high resolutions of 22 nm in the x/y relative displacement and 27 nm in the z relative displacement for fast spatial matching of the two laser beams.This study has potential applications in scenarios that require the spatial matching of multiple laser beams,and the field of views of different objectives,for example,in a microscope with high precision.