Diverse spatial mode bases can be exploited in mode-division multiplexing(MDM)to sustain the capacity growth in fiber-optic communications,such as linearly polarized(LP)modes,vector modes,LP orbital angular momentum(L...Diverse spatial mode bases can be exploited in mode-division multiplexing(MDM)to sustain the capacity growth in fiber-optic communications,such as linearly polarized(LP)modes,vector modes,LP orbital angular momentum(LP-OAM)modes,and circularly polarized OAM(CP-OAM)modes.Nevertheless,which kind of mode bases is more appropriate to be utilized in fiber still remains unclear.Here,we aim to find the superior mode basis in MDM fiber-optic communications via a system-level comparison in air-core fiber(ACF).We first investigate the walk-off effect of four spatial mode bases over 1-km ACF,where LP and LP-OAM modes show intrinsic mode walk-off,while it is negligible for vector and CP-OAM modes.We then study the mode coupling effect of degenerate vector and CP-OAM modes over 1-km ACF under fiber perturbations,where degenerate even and odd vector modes suffer severe mode cross talk,while negligible for highorder degenerate CP-OAM modes based on the laws of angular momentum conservation.Moreover,we comprehensively evaluate the system-level performance for data-carrying single-channel and two-channel MDM transmission with different spatial mode bases under various kinds of fiber perturbations(bending,twisting,pressing,winding,and out-of-plane moving).The obtained results indicate that the CP-OAM mode basis shows superiority compared to other mode bases in MDM fiber-optic communications without using multiple-input multiple-output digital signal processing.Our findings may pave the way for robust shortreach MDM optical interconnects for data centers and high-performance computing.展开更多
Rotational Doppler effect has made tremendous development in both theoretical and applied research over the last decade.Different from the inertial thinking of focusing on the scalar field dominated by helical phase l...Rotational Doppler effect has made tremendous development in both theoretical and applied research over the last decade.Different from the inertial thinking of focusing on the scalar field dominated by helical phase light,we have revealed a vectorial Doppler effect in our previous work,which is based on the spatially variant polarized light fields to simultaneously acquire the speed and direction of a target.Here,further,we propose a method to construct a flexible and robust velocimeter based on that novel effect by employing an air-core fiber with kilometer-length scale for remotely measuring the vectorial information of angular velocity in situ.In addition,we experimentally substantiate that the measurement system still has commendable accuracy in determining the direction of movement even when the air-core fiber is interfered by the external environment.The demonstrations prove the potential of vectorial Doppler effect in practical scenarios and remote measurements.展开更多
Recently,structured light beams have attracted substantial attention in many applications,including optical communications,imaging,optical tweezers,and quantum optics.We propose and experimentally demonstrate a reconf...Recently,structured light beams have attracted substantial attention in many applications,including optical communications,imaging,optical tweezers,and quantum optics.We propose and experimentally demonstrate a reconfigurable structured light beam generator in order to generate diverse structured light beams with adjustable beam types,beam orders,and beam sizes.By controlling the sizes of generated free-space structured light beams,free-space orbital angular momentum(OAM)beams and vector beams are coupled into an air-core fiber.To verify that our structured light generator enables generating structured light with high beam quality,polarization distributions and mode purity of generated OAM beams and vector beams in both free space and air-core fiber are characterized.Such a structured light generator may pave the way for future applications based on higher-order structured light beams.展开更多
We report a study investigating the effects of thermal annealing on the optical properties of Si-Ge alloy-core silica-cladded fibers.Low temperature fiber draw was performed with a laboratory-made draw tower at 1760&#...We report a study investigating the effects of thermal annealing on the optical properties of Si-Ge alloy-core silica-cladded fibers.Low temperature fiber draw was performed with a laboratory-made draw tower at 1760°C that minimizes impurity diffusion from cladding to the core.As a post-drawing process,Si-Ge core fibers were annealed in a box furnace to alter the core structure.Microstructural and optical properties of fibers were investigated,and transmission losses were measured as 28 dB/cm at 6.1μm.Numerical studies were performed to analyze the experimental results and to find the optimum structure for low loss semiconductor-core glass-cladded fibers.展开更多
Dispersion compensation with few-mode fibers is emerging as a promising technique that can provide full dispersion and dispersion-slope compensation. The inherent modal path diversity of these fibers allows implementa...Dispersion compensation with few-mode fibers is emerging as a promising technique that can provide full dispersion and dispersion-slope compensation. The inherent modal path diversity of these fibers allows implementation of static as well as tunable dispersion management schemes. In addition, the low non-linearity of this technology can improve system OSNR, leading to enhancements in transmission distances.展开更多
Interest in the nonlinear properties of multi-mode optical waveguides has seen a recent resurgence on account of the large dimensionality afforded by the platform. The large volume of modes in these waveguides provide...Interest in the nonlinear properties of multi-mode optical waveguides has seen a recent resurgence on account of the large dimensionality afforded by the platform. The large volume of modes in these waveguides provides a new spatial degree of freedom for phase matching nonlinear optical processes. However, this spatial dimension is quantized, which narrows the conversion bandwidths of intermodal processes and constrains spectral and temporal tailoring of the light. Here we show that by engineering the relative group velocity within the spatial dimension, we can tailor the phase-matching bandwidth of intermodal parametric nonlinearities. We demonstrate group-velocity-tailored parametric nonlinear mixing between higher-order modes in a multi-mode fiber with gain bandwidths that are more than an order of magnitude larger than that previously thought possible for intermodal four-wave mixing. As evidence of the technological utility of this methodology, we seed this process to generate the first high-peak-power wavelength-tunable all-fiber quasi-CW laser in the Ti:sapphire wavelength regime.More generally, with the combination of intermodal interactions, which dramatically expand the phase-matching degrees of freedom for nonlinear optics, and intermodal group-velocity engineering, which enables tailoring of the bandwidth of such interactions, we showcase a platform for nonlinear optics that can be broadband while being wavelength agnostic.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.62125503 and 62261160388)the National Key R&D Program of China(Grant No.2019YFB2203604)+2 种基金the Key R&D Program of Hubei Province of China(Grant Nos.2020BAB001 and 2021BAA024)the Shenzhen Science and Technology Program(Grant No.JCYJ20200109114018750)the Innovation Project of Optics Valley Laboratory(Grant No.OVL2021BG004)。
文摘Diverse spatial mode bases can be exploited in mode-division multiplexing(MDM)to sustain the capacity growth in fiber-optic communications,such as linearly polarized(LP)modes,vector modes,LP orbital angular momentum(LP-OAM)modes,and circularly polarized OAM(CP-OAM)modes.Nevertheless,which kind of mode bases is more appropriate to be utilized in fiber still remains unclear.Here,we aim to find the superior mode basis in MDM fiber-optic communications via a system-level comparison in air-core fiber(ACF).We first investigate the walk-off effect of four spatial mode bases over 1-km ACF,where LP and LP-OAM modes show intrinsic mode walk-off,while it is negligible for vector and CP-OAM modes.We then study the mode coupling effect of degenerate vector and CP-OAM modes over 1-km ACF under fiber perturbations,where degenerate even and odd vector modes suffer severe mode cross talk,while negligible for highorder degenerate CP-OAM modes based on the laws of angular momentum conservation.Moreover,we comprehensively evaluate the system-level performance for data-carrying single-channel and two-channel MDM transmission with different spatial mode bases under various kinds of fiber perturbations(bending,twisting,pressing,winding,and out-of-plane moving).The obtained results indicate that the CP-OAM mode basis shows superiority compared to other mode bases in MDM fiber-optic communications without using multiple-input multiple-output digital signal processing.Our findings may pave the way for robust shortreach MDM optical interconnects for data centers and high-performance computing.
基金the National Natural Science Foundation of China(NSFC)(62125503,11774116,and 61905081)the Key R&D Program of Hubei Province of China(2020BAB001 and 2021BAA024)+2 种基金the Key R&D Program of Guangdong Province(2018B030325002)the Science and Technology Innovation Commission of Shenzhen(JCYJ20200109114018750)the Fundamental Research Funds for the Central Universities(2019kfyRCPY037).
文摘Rotational Doppler effect has made tremendous development in both theoretical and applied research over the last decade.Different from the inertial thinking of focusing on the scalar field dominated by helical phase light,we have revealed a vectorial Doppler effect in our previous work,which is based on the spatially variant polarized light fields to simultaneously acquire the speed and direction of a target.Here,further,we propose a method to construct a flexible and robust velocimeter based on that novel effect by employing an air-core fiber with kilometer-length scale for remotely measuring the vectorial information of angular velocity in situ.In addition,we experimentally substantiate that the measurement system still has commendable accuracy in determining the direction of movement even when the air-core fiber is interfered by the external environment.The demonstrations prove the potential of vectorial Doppler effect in practical scenarios and remote measurements.
基金supported by the National Natural Science Foundation of China(Grant Nos.62125503 and 62261160388)the Key R&D Program of Hubei Province of China(Grant Nos.2020BAB001 and 2021BAA024)+3 种基金the Key R&D Program of Guangdong Province(Grant No.2018B030325002)the Shenzhen Science and Technology Program(Grant No.JCYJ20200109114018750)the Open Projects Foundation of State Key Laboratory of Optical Fiber and Cable Manufacture Technology(Grant No.SKLD2201)the Innovation Project of Optics Valley Laboratory(Grant No.OVL2021BG004).
文摘Recently,structured light beams have attracted substantial attention in many applications,including optical communications,imaging,optical tweezers,and quantum optics.We propose and experimentally demonstrate a reconfigurable structured light beam generator in order to generate diverse structured light beams with adjustable beam types,beam orders,and beam sizes.By controlling the sizes of generated free-space structured light beams,free-space orbital angular momentum(OAM)beams and vector beams are coupled into an air-core fiber.To verify that our structured light generator enables generating structured light with high beam quality,polarization distributions and mode purity of generated OAM beams and vector beams in both free space and air-core fiber are characterized.Such a structured light generator may pave the way for future applications based on higher-order structured light beams.
基金This project is supported by the National Science Foundation(NSF,Grant number CMMI-1301108,2013).
文摘We report a study investigating the effects of thermal annealing on the optical properties of Si-Ge alloy-core silica-cladded fibers.Low temperature fiber draw was performed with a laboratory-made draw tower at 1760°C that minimizes impurity diffusion from cladding to the core.As a post-drawing process,Si-Ge core fibers were annealed in a box furnace to alter the core structure.Microstructural and optical properties of fibers were investigated,and transmission losses were measured as 28 dB/cm at 6.1μm.Numerical studies were performed to analyze the experimental results and to find the optimum structure for low loss semiconductor-core glass-cladded fibers.
文摘Dispersion compensation with few-mode fibers is emerging as a promising technique that can provide full dispersion and dispersion-slope compensation. The inherent modal path diversity of these fibers allows implementation of static as well as tunable dispersion management schemes. In addition, the low non-linearity of this technology can improve system OSNR, leading to enhancements in transmission distances.
基金Air Force Office of Scientific Research(AFOSR)(FA9550-14-1-0165)Office of Naval Research(ONR)(N00014-17-1-2519)
文摘Interest in the nonlinear properties of multi-mode optical waveguides has seen a recent resurgence on account of the large dimensionality afforded by the platform. The large volume of modes in these waveguides provides a new spatial degree of freedom for phase matching nonlinear optical processes. However, this spatial dimension is quantized, which narrows the conversion bandwidths of intermodal processes and constrains spectral and temporal tailoring of the light. Here we show that by engineering the relative group velocity within the spatial dimension, we can tailor the phase-matching bandwidth of intermodal parametric nonlinearities. We demonstrate group-velocity-tailored parametric nonlinear mixing between higher-order modes in a multi-mode fiber with gain bandwidths that are more than an order of magnitude larger than that previously thought possible for intermodal four-wave mixing. As evidence of the technological utility of this methodology, we seed this process to generate the first high-peak-power wavelength-tunable all-fiber quasi-CW laser in the Ti:sapphire wavelength regime.More generally, with the combination of intermodal interactions, which dramatically expand the phase-matching degrees of freedom for nonlinear optics, and intermodal group-velocity engineering, which enables tailoring of the bandwidth of such interactions, we showcase a platform for nonlinear optics that can be broadband while being wavelength agnostic.
