In a few-mode erbium-doped fiber(FM-EDF),which is a key section in a space-division multiplexing(SDM)communication system,linearly polarized(LP)and orbital angular momentum(OAM)modes,as twomode bases with different ph...In a few-mode erbium-doped fiber(FM-EDF),which is a key section in a space-division multiplexing(SDM)communication system,linearly polarized(LP)and orbital angular momentum(OAM)modes,as twomode bases with different phase profiles,can be transformed into each other.In principle,the LP and OAM modes have a different mode spatial intensity distribution and a gain difference for FM-EDF amplifiers.How to analyze and characterize the differential mode-bases gain(DMBG)is important,but still an issue.We build,for the first time to our knowledge,a local analysis model composed of discrete elements of the FM-EDF cross section in areas of mode spatial intensity distribution azimuthal variation.Using the model of the two mode bases,analysis of local particle number distribution and detailed description of the local gain difference are realized,and the overall gain difference between the two mode bases is obtained.By building an amplifier system based on mode phase profile controlling,the gain of two mode bases is characterized experimentally.The measured DMBG is∼0.8 dB in the second-order mode,which is consistent with the simulation result.This result provides a potential way to reduce the mode gain difference in the FM-EDF,which is important in improving the performance of the SDM communication system.展开更多
Space division multiplexing(SDM)can achieve higher communication transmission capacity by exploiting more spatial channels in a single optical fiber.For weakly coupled few-mode fiber,different mode groups(MGs)are high...Space division multiplexing(SDM)can achieve higher communication transmission capacity by exploiting more spatial channels in a single optical fiber.For weakly coupled few-mode fiber,different mode groups(MGs)are highly isolated from each other,so the SDM system can be simplified by utilizing MG multiplexing and intensity modulation direct detection.A key issue to be addressed here is MG demultiplexing,which requires processing all the modes within a single MG in contrast to MG multiplexing.Benefiting from the great light manipulation freedom of the diffractive optical network(DON),we achieve efficient separation of the MGs and receive them with the multimode fiber(MMF)array.To fully exploit the mode field freedom of the MMF,a non-deterministic mode conversion strategy is proposed here to optimize the DON,which enables high-efficiency demultiplexing with a much smaller number of phase plates.As a validation,we design a 6-MG demultiplexer consisting of only five phase plates;each MG is constituted by several orbital angular momentum modes.The designed average loss and crosstalk at the wavelength of 1550 nm are 0.5 dB and-25 dB,respectively.In the experiment,the loss after coupling to the MMF ranged from 4.1 to 4.9 dB,with an average of 4.5 dB.The inter-MG crosstalk is better than-12 dB,with an average of-18 dB.These results well support the proposed scheme and will provide a practical solution to the MG demultiplexing problem in a short-distance SDM system.展开更多
The quickly increasing data transfer load requires an urgent revolution in current optical communication. Orbital angular momentum(OAM) multiplexing is a potential candidate with its ability to considerably enhance th...The quickly increasing data transfer load requires an urgent revolution in current optical communication. Orbital angular momentum(OAM) multiplexing is a potential candidate with its ability to considerably enhance the capacity of communication. However, the lack of a compact, efficient, and integrated OAM(de)multiplexer prevents it from being widely applied. By attaching vortex gratings onto the facets of a few-mode fiber, we demonstrate an integrated fiber-based OAM(de)multiplexer. A vortex grating fabricated on the fiber facet enables the direct multiplexing of OAM states at one port and the demultiplexing of OAM states at the other port. The measured bit error rate of the carrier signal after propagating through a 5-km few-mode fiber confirms the validity and effectiveness of the proposed approach. The scheme offers advantages in future high-capacity OAM communication based on optical fiber.展开更多
Tungsten disulfide （WS2）, as a representative layered transition metal dichalcogenide （TMDC） material, possesses important potential for applications in highly sensitive sensors. Here, a sensitivity-enhanced surfa...Tungsten disulfide （WS2）, as a representative layered transition metal dichalcogenide （TMDC） material, possesses important potential for applications in highly sensitive sensors. Here, a sensitivity-enhanced surface plasmon resonance （SPR） sensor with a metal film modified by an overlayer of WS2 nanosheets is proposed and demo onstrated. The SPR sensitivity is related to the thickness of the WS2 overlayer, which can be tailored by coating a WS2 ethanol suspension with different concentrations or by the number of times of repeated post-coating. Benefitting from its large surface area, high refractive index, and unique optoelectronic properties, the WS2 nanosheet overlayer coated on the gold film significantly improves the sensing sensitivity. The highest sensitivity （up to 2459.3 nm/RIU） in the experiment is achieved by coating the WS2 suspension once. Compared to the case without a WS2 overlayer, this result shows a sensitivity enhancement of 26.6%. The influence of the WS2 nano- sheet overlayer on the sensing performance improvement is analyzed and discussed. Moreover, the proposed WS2 SPR sensor has a linear correlation coefficient of 99.76% in refractive index range of 1.333 to 1.360. Besides sensitivity enhancement, the WS2 nanosheet overlayer is able to show additional advantages, such as protection of metal film from oxidation, tunability of the resonance wavelength region, biocompatibility, capability of vapor, and gas sensing.展开更多
This paper firstly,to the best of our knowledge,proposed two-dimensional(2D)encryption based on the Arnold transformation for implementing a secure DC-biased optical orthogonal time-frequency multiplexing(DCO-OTFM)in ...This paper firstly,to the best of our knowledge,proposed two-dimensional(2D)encryption based on the Arnold transformation for implementing a secure DC-biased optical orthogonal time-frequency multiplexing(DCO-OTFM)in optical-wireless communications(OWCs).The encrypted data is transformed to the particular 2D matrix and decrypted by the only key to get the correct information.Meanwhile,the number of keys in 2D encryption is enormous,which prevents eavesdroppers from exhaustively searching secret keys rapidly to find the right decryption.Numerical results demonstrate that the secure DCO-OTFM based on 2D encryption can effectively prevent signal decryption from the eavesdropper,which has good secure performance for applying in OWC.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2019YFA0706300)the National Natural Science Foundation of China(Grant Nos.U22B2010,62035018,and U2001601)+1 种基金the Program of Marine Economy Development Special Fund(Six Marine Industries)under the Department of Natural Resources of Guangdong Province(Grant No.GDNRC[2024]16)the project supported by the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.SML2023SP231).
文摘In a few-mode erbium-doped fiber(FM-EDF),which is a key section in a space-division multiplexing(SDM)communication system,linearly polarized(LP)and orbital angular momentum(OAM)modes,as twomode bases with different phase profiles,can be transformed into each other.In principle,the LP and OAM modes have a different mode spatial intensity distribution and a gain difference for FM-EDF amplifiers.How to analyze and characterize the differential mode-bases gain(DMBG)is important,but still an issue.We build,for the first time to our knowledge,a local analysis model composed of discrete elements of the FM-EDF cross section in areas of mode spatial intensity distribution azimuthal variation.Using the model of the two mode bases,analysis of local particle number distribution and detailed description of the local gain difference are realized,and the overall gain difference between the two mode bases is obtained.By building an amplifier system based on mode phase profile controlling,the gain of two mode bases is characterized experimentally.The measured DMBG is∼0.8 dB in the second-order mode,which is consistent with the simulation result.This result provides a potential way to reduce the mode gain difference in the FM-EDF,which is important in improving the performance of the SDM communication system.
基金Guangdong ST Programme(2024B0101030001)National Key Research and Development Program of China(2019YFA0706300,2024YFB2908100)+2 种基金National Natural Science Foundation of China(U22B2010,62035018,U2001601,62227819)The Program of Marine Economy Development Special Fund(Six Marine Industries)under Department of Natural Resources of Guangdong Province(GDNRC[2024]16)Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(SML2023SP231)。
文摘Space division multiplexing(SDM)can achieve higher communication transmission capacity by exploiting more spatial channels in a single optical fiber.For weakly coupled few-mode fiber,different mode groups(MGs)are highly isolated from each other,so the SDM system can be simplified by utilizing MG multiplexing and intensity modulation direct detection.A key issue to be addressed here is MG demultiplexing,which requires processing all the modes within a single MG in contrast to MG multiplexing.Benefiting from the great light manipulation freedom of the diffractive optical network(DON),we achieve efficient separation of the MGs and receive them with the multimode fiber(MMF)array.To fully exploit the mode field freedom of the MMF,a non-deterministic mode conversion strategy is proposed here to optimize the DON,which enables high-efficiency demultiplexing with a much smaller number of phase plates.As a validation,we design a 6-MG demultiplexer consisting of only five phase plates;each MG is constituted by several orbital angular momentum modes.The designed average loss and crosstalk at the wavelength of 1550 nm are 0.5 dB and-25 dB,respectively.In the experiment,the loss after coupling to the MMF ranged from 4.1 to 4.9 dB,with an average of 4.5 dB.The inter-MG crosstalk is better than-12 dB,with an average of-18 dB.These results well support the proposed scheme and will provide a practical solution to the MG demultiplexing problem in a short-distance SDM system.
基金National Natural Science Foundation of China(NSFC)(U1701661,61427819,61525502,61435006,11604218,61601199,61775085,61405121)Science and Technology Innovation Commission of Shenzhen(KQCS2015032416183980,KQJSCX20160226193555889,KQTD2015071016560101,KQTD2017033011044403,ZDSYS201703031605029)+2 种基金Leading Talents of Guangdong Province(00201505)Natural Science Foundation of Guangdong Province(2016A030312010,2017A030313351)National Key Basic Research Program of China(973)(2015CB352004)
文摘The quickly increasing data transfer load requires an urgent revolution in current optical communication. Orbital angular momentum(OAM) multiplexing is a potential candidate with its ability to considerably enhance the capacity of communication. However, the lack of a compact, efficient, and integrated OAM(de)multiplexer prevents it from being widely applied. By attaching vortex gratings onto the facets of a few-mode fiber, we demonstrate an integrated fiber-based OAM(de)multiplexer. A vortex grating fabricated on the fiber facet enables the direct multiplexing of OAM states at one port and the demultiplexing of OAM states at the other port. The measured bit error rate of the carrier signal after propagating through a 5-km few-mode fiber confirms the validity and effectiveness of the proposed approach. The scheme offers advantages in future high-capacity OAM communication based on optical fiber.
基金National Natural Science Foundation of China(NSFC)(61575084,61705087,61705046,61361166006,61401176,61405075,61475066,61505069)Natural Science Foundation of Guangdong Province(2015A030313320,S2013050014606,2014A030313377,2014A030310205,2015A030306046,2016A030311019,2016A030313079,2016A030310098)+2 种基金Science and Technology Projects of Guangdong Province(2017A010101013,2012A032300016,2014B010120002,2014B010117002,2015A020213006,2015B010125007,2016B010111003,2016A010101017)Science and Technology Project of Guangzhou(201707010500,201506010046,201607010134,201605030002,201610010026,201604040005)China Postdoctoral Science Foundation(2017M612608)
文摘Tungsten disulfide （WS2）, as a representative layered transition metal dichalcogenide （TMDC） material, possesses important potential for applications in highly sensitive sensors. Here, a sensitivity-enhanced surface plasmon resonance （SPR） sensor with a metal film modified by an overlayer of WS2 nanosheets is proposed and demo onstrated. The SPR sensitivity is related to the thickness of the WS2 overlayer, which can be tailored by coating a WS2 ethanol suspension with different concentrations or by the number of times of repeated post-coating. Benefitting from its large surface area, high refractive index, and unique optoelectronic properties, the WS2 nanosheet overlayer coated on the gold film significantly improves the sensing sensitivity. The highest sensitivity （up to 2459.3 nm/RIU） in the experiment is achieved by coating the WS2 suspension once. Compared to the case without a WS2 overlayer, this result shows a sensitivity enhancement of 26.6%. The influence of the WS2 nano- sheet overlayer on the sensing performance improvement is analyzed and discussed. Moreover, the proposed WS2 SPR sensor has a linear correlation coefficient of 99.76% in refractive index range of 1.333 to 1.360. Besides sensitivity enhancement, the WS2 nanosheet overlayer is able to show additional advantages, such as protection of metal film from oxidation, tunability of the resonance wavelength region, biocompatibility, capability of vapor, and gas sensing.
基金the National Key R&D Program of China(No.2018YFB1802300)the National Natural Science Foundation of China(Nos.61875076 and62005102)+3 种基金the Fundamental Research Funds for the Central Universities(No.21619309)the Leading Talents of Guangdong Province Program(No.00201502)the Natural Science Foundation of Guangdong Province(No.2019A1515011059)the Open Fund of IPOC(BUPT)(No.IPOC2019A001)。
文摘This paper firstly,to the best of our knowledge,proposed two-dimensional(2D)encryption based on the Arnold transformation for implementing a secure DC-biased optical orthogonal time-frequency multiplexing(DCO-OTFM)in optical-wireless communications(OWCs).The encrypted data is transformed to the particular 2D matrix and decrypted by the only key to get the correct information.Meanwhile,the number of keys in 2D encryption is enormous,which prevents eavesdroppers from exhaustively searching secret keys rapidly to find the right decryption.Numerical results demonstrate that the secure DCO-OTFM based on 2D encryption can effectively prevent signal decryption from the eavesdropper,which has good secure performance for applying in OWC.
