We report on the high-power amplification of a 1064 nm linearly polarized laser in an all-fiber polarizationmaintained master oscillator power amplifier,which can operate at an output power level of 1.3 kW.The beam qu...We report on the high-power amplification of a 1064 nm linearly polarized laser in an all-fiber polarizationmaintained master oscillator power amplifier,which can operate at an output power level of 1.3 kW.The beam quality(M^2) was measured to be <1.2 at full power operation.The polarization extinction rate of the fiber amplifier was measured to be above 94% before mode instabilities(MIs) set in,which reduced to about 90% after the onset of MI.The power scaling capability of strategies for suppressing MI is analyzed based on a semianalytical model,the theoretical results of which agree with the experimental results.It shows that mitigating MI by coiling the gain fiber is an effective and practical method in standard double-cladding large mode area fiber,and,by tight coiling of the gain fiber to the radius of 5.5 cm,the MI threshold can be increased to three times higher than that without coiling or loose coiling.Experimental studies have been carried out to verify the idea,which has proved that MI was suppressed successfully in the amplifier by proper coiling.展开更多
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
Polarization-dependent loss(PDL)of mode-division multiplexing(MDM)links has a direct influence on the effective transmission of dual-polarization(DP)signals for large-capacity communication.In this paper,we aim to ide...Polarization-dependent loss(PDL)of mode-division multiplexing(MDM)links has a direct influence on the effective transmission of dual-polarization(DP)signals for large-capacity communication.In this paper,we aim to identify the origin of PDL in MDM systems and optimize the transmission performance of DP signals.The PDL characteristic of the fundamental MDM system with a few-mode polarization controller(FMPC)is theoretically analyzed and verified by experiments.It is shown that the PDL of MDM links arrives at the minimum when the spatial pattern of mode channels is independent of the input polarization angle.The experimental data have good consistency with the theoretical curve.At the same time,the origin of PDL for MDM systems is identified,that is,the mode dependency can be converted into the polarization dependency in the MDM links.The theoretical and experimental results in the paper can guide PDL optimization of DP signals in MDM transmission.展开更多
New approaches are required to prevent the plagues of locusts that threaten crop security in many areas of the world.One such approach is to exploit locusts'polarotactic response effect,enabling their aggregation ...New approaches are required to prevent the plagues of locusts that threaten crop security in many areas of the world.One such approach is to exploit locusts'polarotactic response effect,enabling their aggregation and effective removal from agricultural sites.The current study used linearly partially polarized light with different polarization vectors and a polarotactic response device to test locusts'polarotactic response effect.Results showed that under partially polarized light with linear polarization vectors in the range of 0°-360°,locusts exhibited a sinusoidal-cosine tuning response in specific periods depending on the intensity of the polarization spectrum,and differences in the intensity of the polarization spectrum led to changes in the sensitivity of polarotactic vision at different distances.As the intensity of the illumination increased,the effects of polarized violet,blue,and orange spectra were strongest at far,medium,and close distances,respectively.At the maximum illumination intensity,the differences in the specific sensitivity vector modes at different vision distances were due to variations in the sensitivity of the visual response to the e-vector induced by the optical distance polarization effect of the heterogeneous spectrum.The polarotactic responses were stronger under violet spectrum at 330°and blue spectrum at 0°(360°),while the polarotactic response and aggregation sensitivity were stronger at 240°and the visual trend was sensitive to 180°under orange spectrum.Intriguingly,locusts had different sensitivity thresholds to the intensity of the polarization spectrum,where the polarotactic responses were equal for polarized violet light at a vector of 330°and light energy from various spectral sources.Therefore,combined stimulation with illumination by polarized violet and orange spectra can enhance locusts'polarotactic response effect and regulate the sensitivity of locusts'polarization vision,which provides theoretical support for understanding locusts'polarotactic orientation mechanisms,thereby facilitating the development of polarization-induced light sources for attracting locusts.展开更多
Much attention has been focused on the use of scalar modes for space division multiplexing （SDM）. Alternative vector mode bases offer another solution set for SDM, expanding the available trade-offs in system perfor...Much attention has been focused on the use of scalar modes for space division multiplexing （SDM）. Alternative vector mode bases offer another solution set for SDM, expanding the available trade-offs in system performance and complexity. We present two types of ring core fiber conceived and designed to explore SDM with fibers exhibiting low interactions between supported modes. We review demonstrations of fiber data transmis- sion tbr two separate vector mode bases： one for orbital angular momentum （OAM） modes and one for linearly polarized vector （LPV） modes. The OAM mode demon- strations include short transmissions using commercially available transceivers, as well as kilometer length transmission at extended data rates. The LPV demonstra- tions span kilometer length transmissions at high data rate with coherent detection, as well as a radio over fiber experiment with direct detection of narrowband signals.展开更多
基金funding from the program for the National Science Foundation of China under Grant No.61322505the program for New Century Excellent Talents in University+1 种基金the Innovation Foundation for Excellent Graduates in National University of Defense Technology under Grant No.B120704the Hunan Provincial Innovation Foundation for Postgraduate under Grant No.CX2012B035
文摘We report on the high-power amplification of a 1064 nm linearly polarized laser in an all-fiber polarizationmaintained master oscillator power amplifier,which can operate at an output power level of 1.3 kW.The beam quality(M^2) was measured to be <1.2 at full power operation.The polarization extinction rate of the fiber amplifier was measured to be above 94% before mode instabilities(MIs) set in,which reduced to about 90% after the onset of MI.The power scaling capability of strategies for suppressing MI is analyzed based on a semianalytical model,the theoretical results of which agree with the experimental results.It shows that mitigating MI by coiling the gain fiber is an effective and practical method in standard double-cladding large mode area fiber,and,by tight coiling of the gain fiber to the radius of 5.5 cm,the MI threshold can be increased to three times higher than that without coiling or loose coiling.Experimental studies have been carried out to verify the idea,which has proved that MI was suppressed successfully in the amplifier by proper coiling.
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supported by the National Natural Science Foundation of China(No.62171078)。
文摘Polarization-dependent loss(PDL)of mode-division multiplexing(MDM)links has a direct influence on the effective transmission of dual-polarization(DP)signals for large-capacity communication.In this paper,we aim to identify the origin of PDL in MDM systems and optimize the transmission performance of DP signals.The PDL characteristic of the fundamental MDM system with a few-mode polarization controller(FMPC)is theoretically analyzed and verified by experiments.It is shown that the PDL of MDM links arrives at the minimum when the spatial pattern of mode channels is independent of the input polarization angle.The experimental data have good consistency with the theoretical curve.At the same time,the origin of PDL for MDM systems is identified,that is,the mode dependency can be converted into the polarization dependency in the MDM links.The theoretical and experimental results in the paper can guide PDL optimization of DP signals in MDM transmission.
基金Scientific and Technological Project of Henan Province,China(Grant No.242102111179)the Natural Science Foundation Project of Henan Province,China(Grant No.232300420024).
文摘New approaches are required to prevent the plagues of locusts that threaten crop security in many areas of the world.One such approach is to exploit locusts'polarotactic response effect,enabling their aggregation and effective removal from agricultural sites.The current study used linearly partially polarized light with different polarization vectors and a polarotactic response device to test locusts'polarotactic response effect.Results showed that under partially polarized light with linear polarization vectors in the range of 0°-360°,locusts exhibited a sinusoidal-cosine tuning response in specific periods depending on the intensity of the polarization spectrum,and differences in the intensity of the polarization spectrum led to changes in the sensitivity of polarotactic vision at different distances.As the intensity of the illumination increased,the effects of polarized violet,blue,and orange spectra were strongest at far,medium,and close distances,respectively.At the maximum illumination intensity,the differences in the specific sensitivity vector modes at different vision distances were due to variations in the sensitivity of the visual response to the e-vector induced by the optical distance polarization effect of the heterogeneous spectrum.The polarotactic responses were stronger under violet spectrum at 330°and blue spectrum at 0°(360°),while the polarotactic response and aggregation sensitivity were stronger at 240°and the visual trend was sensitive to 180°under orange spectrum.Intriguingly,locusts had different sensitivity thresholds to the intensity of the polarization spectrum,where the polarotactic responses were equal for polarized violet light at a vector of 330°and light energy from various spectral sources.Therefore,combined stimulation with illumination by polarized violet and orange spectra can enhance locusts'polarotactic response effect and regulate the sensitivity of locusts'polarization vision,which provides theoretical support for understanding locusts'polarotactic orientation mechanisms,thereby facilitating the development of polarization-induced light sources for attracting locusts.
文摘Much attention has been focused on the use of scalar modes for space division multiplexing （SDM）. Alternative vector mode bases offer another solution set for SDM, expanding the available trade-offs in system performance and complexity. We present two types of ring core fiber conceived and designed to explore SDM with fibers exhibiting low interactions between supported modes. We review demonstrations of fiber data transmis- sion tbr two separate vector mode bases： one for orbital angular momentum （OAM） modes and one for linearly polarized vector （LPV） modes. The OAM mode demon- strations include short transmissions using commercially available transceivers, as well as kilometer length transmission at extended data rates. The LPV demonstra- tions span kilometer length transmissions at high data rate with coherent detection, as well as a radio over fiber experiment with direct detection of narrowband signals.
