Novel Even Beam Splitters Based on Subwavelength Binary Simple Periodic Rectangular Structure

In this paper, a novel method of a subwavelength binary simple periodic rectangular structure is presented to realize even beam splitting by combining the rigorous couple-wave analysis with the genetic algorithm. Several even splitters in the terahertz region were designed and one of the silicon-based beam splitters designed to separate one incident beam into four emergent beams has total efficiency up to 92.23 %. Zero-order diffraction efficiency was reduced to less than 0.192 % and the error of uniformity decreased to 6.51 9 10-6. These results break the limitation of even beam splitting based on the traditional scalar theory. In addition, the effects of the incident angle, wavelength, as well as the polarizing angle on the diffraction efficiency and uniformity were also investigated.

Experimental generation and observation of a super-resolution optical tube

We generated a super-resolution optical tube by tightly focusing a binary phase modulated azimuthally polarized laser beam.The binary phase modulation is achieved by a glass substrate with multi-belt concentric ring grooves.We also characterized the 3D beam pro¯le by using a crossshaped knife-edge fabricated on a silicon photo-detector.The size of the super-resolution dark spot in the tube is 0.32
,which remains unchanged for
4
within the tube.This optical tube may¯nd applications in super-resolution microscopy,optical trapping and particle acceleration.

The first symbiotic stars from the LAMOST survey

Symbiotic stars are interacting binary systems with the longest orbital periods. They are typically formed by a white dwarf and a red giant that are embedded in a nebula. These objects are natural astrophysical laboratories for studying the evolution of binaries. Current estimates of the population of symbiotic stars in the Milky Way vary from 3000 up to 400 000. However, a current census has found less than 300. The Large sky Area Multi-Object fiber Spectroscopic Telescope（LAMOST） survey can obtain hundreds of thousands of stellar spectra per year, providing a good opportunity to search for new symbiotic stars. We detect four such binaries among 4 147 802 spectra released by LAMOST, of which two are new identifications. The first is LAMOST J12280490–014825.7, considered to be an S-type halo symbiotic star. The second is LAMOST J202629.80＋423652.0, a D-type symbiotic star.

Mutual optical format conversion between on-of keying and binary phase-shift keying based on stimulated brillouin scattering

We propose and experimentally demonstrate mutual optical format conversion between signals characterized as 10-Gb/s nonreturn-to-zero on-of-keying(NRZ-OOK) and NRZ binary phase-shift keying(BPSK) types. The conversion is based on stimulated Brillouin scattering(SBS) in a single-mode optical fber. An OOK signal is converted into a BPSK signal through optical carrier absorption, for which a SBS loss of 30 MHz is used in long-haul transmission. The converted BPSK signal is reverted to an OOK signal with a corresponding SBS gain of 30 MHz for direct detection. The proposed OOK-to-BPSK and BPSK-to-OOK format conversions can be implemented in transmitter and receiver nodes by using a laser source as the Brillouin pump.

High throughput direct writing of a mesoscale binary optical element by femtosecond long focal depth beams

Bessel beams have multiple applications owing to their propagation-invariant properties,including particle trapping,optical coherence tomography,and material processing.However,traditional Bessel-beam shaping techniques require bulky components,which limits the development of miniaturized optical systems for integration with other devices.Here,we report a novel femtosecond laser direct writing strategy for fabricating mesoscale(from submicrometer to subcentimeter)binary optical elements with microscale resolution.This strategy utilizes femtosecond beams with a long focal depth to increase throughput while reducing the constraints on critical sample positioning.As a demonstration,we manufactured and characterized a 2.2 mm diameter binary axicon.The experimentally measured quasi-Bessel beam intensity distribution and the numerical results were remarkably consistent,demonstrating a suitable tradeoff between the overall size,efficiency,and structural fidelity.Furthermore,a compact Bessel lens containing binary axicons was constructed and successfully used for femtosecond laser mask-less ablation of periodic grating-type surface plasmon polariton excitation units.The demonstrated approach shows significant potential for fabricating customizable integrated optical components.

Gene Disease Diagnostic System

Binary optics, where the optical element can be fabricated on a thin glass plate with micro-ion-etching film layer, has been widely applied in recent years. A novel optical scanning system for gene disease diagnostics described in this paper has four kinds of optical devices, including beam splitters, an array lens, an array filter and detection arrays. A software was developed to design the binary optics system using an iterative method. Two beam splitters were designed and fabricated, which can divide a beam into a 9×9 array or into a 13×13 array. The beam splitters have good diffraction efficiencies (>70%) and an even energy distribution. The gene disease diagnostic system is a portable biochip and binary optics technology. The binary optical devices in the non-confocal scanning system can raise the fluorescence detection sensitivity of the micro-array hybrid biochip.