An optical vortex having an isolated point singularity is associated with the spatial structure of light waves.A polarization vortex(vector beam) with a polarization singularity has spatially variant polarizations. A ...An optical vortex having an isolated point singularity is associated with the spatial structure of light waves.A polarization vortex(vector beam) with a polarization singularity has spatially variant polarizations. A phase vortex with phase singularity or screw dislocation has a spiral phase front. The optical vortex has recently gained increasing interest in optical trapping, optical tweezers, laser machining, microscopy, quantum information processing, and optical communications. In this paper, we review recent advances in optical communications using optical vortices. First, basic concepts of polarization/phase vortex modulation and multiplexing in communications and key techniques of polarization/phase vortex generation and(de)multiplexing are introduced. Second, free-space and fiber optical communications using optical vortex modulation and optical vortex multiplexing are presented. Finally, key challenges and perspectives of optical communications using optical vortices are discussed. It is expected that optical vortices exploiting the space physical dimension of light waves might find more interesting applications in optical communications and interconnects.展开更多
We investigate the atmospheric turbulence effects on orbital angular momentum(OAM) spectra of different kinds of vortex beams, including Laguerre–Gaussian(LG) beams and Bessel beams, numerically. We generate the holo...We investigate the atmospheric turbulence effects on orbital angular momentum(OAM) spectra of different kinds of vortex beams, including Laguerre–Gaussian(LG) beams and Bessel beams, numerically. We generate the holograms of atmospheric turbulence with different structure constants of the refractive index. The OAM spectra of distorted single-mode or multiplexed LG beams and Bessel beams are analyzed. Compared with the OAM spectra of the two kinds of vortex beams, the spectrum of the Bessel beams is more dispersive. The results illustrate that Bessel beams suffer more from turbulent atmosphere than LG beams.展开更多
We experimentally demonstrate mode-division multiplexed(MDM)transmission using eight orbital angular momentum(OAM)modes over a single span of 100-km low-attenuation and low-crosstalk ring-core fiber(RCF).Each OAM mode...We experimentally demonstrate mode-division multiplexed(MDM)transmission using eight orbital angular momentum(OAM)modes over a single span of 100-km low-attenuation and low-crosstalk ring-core fiber(RCF).Each OAM mode channel carries 10 wavelength-division multiplexing(WDM)signal channels in the C band,with each WDM channel in turn transmitting 16-GBaud quadrature phase-shift keying signal.An aggregate capacity of 2.56 Tbit/s and an overall spectral efficiency of 10.24 bit/(s·Hz)are realized.The capacity-distance product of 256(Tbit/s)·km is the largest reported so far for OAM fiber communications systems to the best of our knowledge.Exploiting the low crosstalk between the OAM mode groups in the RCF,the scheme only requires the use of modular 4×4 multiple-input multiple-output processing,and it can therefore be scaled up in the number of MDM channels without increasing the complexity of signal processing.展开更多
A facile colloidal route to synthesize MoSe2 porous microspheres with diameters of 400-600 nm made up of MoSe2 monolayer flakes （-0.7 nm in thickness） is reported. The solvents trioctylamine （TOA） and oleylamine ...A facile colloidal route to synthesize MoSe2 porous microspheres with diameters of 400-600 nm made up of MoSe2 monolayer flakes （-0.7 nm in thickness） is reported. The solvents trioctylamine （TOA） and oleylamine （OAM） are found to play important roles in the formation of MoSe2 microspheres, whereby TOA determines the three-dimensional （3D） microspherical morphology and OAM directs the formation of MoSes monolayer flakes. The robust 3D MoSe2 microspheres exhibit remarkable activity and durability for the electrocatalytic hydrogen evolution reaction （HER） in acid, maintaining a small onset overpotential of -77 mV and keeping a small overpotential of 100 mV for a current density of 5 mA/cm2 after 1,000 cycles. In addition, similar 3D WSe2 microspheres can also be prepared by using this method. We expect this facile colloidal route could further be expanded to synthesize other porous structures which will find applications in fields such as in energy storage, catalysis, and sensing.展开更多
基金National Basic Research Program of China(973Program)(2014CB340004)National Natural Science Foundation of China(NSFC)(11274131,11574001,61222502)+4 种基金National Program for Support of Top-Notch Young ProfessionalsProgram for New Century Excellent Talents in University(NCET)(NCET-11-0182)Wuhan Science and Technology Plan Project(2014070404010201)Open Program from State Key Laboratory of Advanced Optical Communication Systems and Networks(2016GZKF0JT007)Open Projects Foundation of Yangtze Optical Fiber and Cable Joint Stock Limited Company(YOFC)(SKLD1504)
文摘An optical vortex having an isolated point singularity is associated with the spatial structure of light waves.A polarization vortex(vector beam) with a polarization singularity has spatially variant polarizations. A phase vortex with phase singularity or screw dislocation has a spiral phase front. The optical vortex has recently gained increasing interest in optical trapping, optical tweezers, laser machining, microscopy, quantum information processing, and optical communications. In this paper, we review recent advances in optical communications using optical vortices. First, basic concepts of polarization/phase vortex modulation and multiplexing in communications and key techniques of polarization/phase vortex generation and(de)multiplexing are introduced. Second, free-space and fiber optical communications using optical vortex modulation and optical vortex multiplexing are presented. Finally, key challenges and perspectives of optical communications using optical vortices are discussed. It is expected that optical vortices exploiting the space physical dimension of light waves might find more interesting applications in optical communications and interconnects.
基金National Basic Research Program of China(973Program)(2014CB340004,2014CB340002)
文摘We investigate the atmospheric turbulence effects on orbital angular momentum(OAM) spectra of different kinds of vortex beams, including Laguerre–Gaussian(LG) beams and Bessel beams, numerically. We generate the holograms of atmospheric turbulence with different structure constants of the refractive index. The OAM spectra of distorted single-mode or multiplexed LG beams and Bessel beams are analyzed. Compared with the OAM spectra of the two kinds of vortex beams, the spectrum of the Bessel beams is more dispersive. The results illustrate that Bessel beams suffer more from turbulent atmosphere than LG beams.
基金National Key Research and Development Program of China(2018YFB1801800,2019YFA0706300)NSFC-Guangdong Joint Program(U1701661)+3 种基金National Natural Science Foundation of China(61875233)Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2017BT01X121)Guangdong Natural Science Foundation(2016A030313289)Open Projects Foundation of State Key Laboratory of Optical Fiber and Cable Manufacture Technology(YOFC)(SKLD1806)。
文摘We experimentally demonstrate mode-division multiplexed(MDM)transmission using eight orbital angular momentum(OAM)modes over a single span of 100-km low-attenuation and low-crosstalk ring-core fiber(RCF).Each OAM mode channel carries 10 wavelength-division multiplexing(WDM)signal channels in the C band,with each WDM channel in turn transmitting 16-GBaud quadrature phase-shift keying signal.An aggregate capacity of 2.56 Tbit/s and an overall spectral efficiency of 10.24 bit/(s·Hz)are realized.The capacity-distance product of 256(Tbit/s)·km is the largest reported so far for OAM fiber communications systems to the best of our knowledge.Exploiting the low crosstalk between the OAM mode groups in the RCF,the scheme only requires the use of modular 4×4 multiple-input multiple-output processing,and it can therefore be scaled up in the number of MDM channels without increasing the complexity of signal processing.
文摘A facile colloidal route to synthesize MoSe2 porous microspheres with diameters of 400-600 nm made up of MoSe2 monolayer flakes （-0.7 nm in thickness） is reported. The solvents trioctylamine （TOA） and oleylamine （OAM） are found to play important roles in the formation of MoSe2 microspheres, whereby TOA determines the three-dimensional （3D） microspherical morphology and OAM directs the formation of MoSes monolayer flakes. The robust 3D MoSe2 microspheres exhibit remarkable activity and durability for the electrocatalytic hydrogen evolution reaction （HER） in acid, maintaining a small onset overpotential of -77 mV and keeping a small overpotential of 100 mV for a current density of 5 mA/cm2 after 1,000 cycles. In addition, similar 3D WSe2 microspheres can also be prepared by using this method. We expect this facile colloidal route could further be expanded to synthesize other porous structures which will find applications in fields such as in energy storage, catalysis, and sensing.
