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
A highly efficient on-chip acousto-optic modulator is as a key component and occupies an exceptional position in microwave-to-optical conversion.Homogeneous thin-film lithium niobate is preferentially employed to buil...A highly efficient on-chip acousto-optic modulator is as a key component and occupies an exceptional position in microwave-to-optical conversion.Homogeneous thin-film lithium niobate is preferentially employed to build the suspended configuration for the acoustic resonant cavity,with the aim of improving the modulation efficiency of the device.However,the limited cavity length and complex fabrication recipe of the suspended prototype restrain further breakthroughs in modulation efficiency and impose challenges for waveguide fabrication.In this work,based on a nonsuspended thin-film lithium niobate-chalcogenide glass hybrid Mach-Zehnder interferometer waveguide platform,we propose and demonstrate a built-in push-pull acousto-optic modulator with a half-wave-voltage-length product VnL as low as 0.03 V cm that presents a modulation efficiency comparable to that of a state-of-the-art suspended counterpart.A microwave modulation link is demonstrated using our developed built-in push-pull acousto-optic modulator,which has the advantage of low power consumption.The nontrivial acousto-optic modulation performance benefits from the superior photoelastic property of the chalcogenide membrane and the completely bidirectional participation of the antisymmetric Rayleigh surface acoustic wave mode excited by the impedance-matched interdigital transducer,overcoming the issue of low modulation efficiency induced by the incoordinate energy attenuation of acoustic waves applied to the Mach-Zehnder interferometer with two arms in traditional push-pull acousto-optic modulators.展开更多
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We acknowledge the funding support provided by the Key Project in Broadband Communication and New Network of the Ministry of Science and Technology(MOST)(No.2019YFB1803904)the National Natural Science Foundation of China(Grant Nos.62175095,61805104,62105377,U2001601,61935013)+1 种基金the Science Foundation of Guangzhou City(202102020593)the China Postdoctoral Science Foundation(2021M693599).
文摘A highly efficient on-chip acousto-optic modulator is as a key component and occupies an exceptional position in microwave-to-optical conversion.Homogeneous thin-film lithium niobate is preferentially employed to build the suspended configuration for the acoustic resonant cavity,with the aim of improving the modulation efficiency of the device.However,the limited cavity length and complex fabrication recipe of the suspended prototype restrain further breakthroughs in modulation efficiency and impose challenges for waveguide fabrication.In this work,based on a nonsuspended thin-film lithium niobate-chalcogenide glass hybrid Mach-Zehnder interferometer waveguide platform,we propose and demonstrate a built-in push-pull acousto-optic modulator with a half-wave-voltage-length product VnL as low as 0.03 V cm that presents a modulation efficiency comparable to that of a state-of-the-art suspended counterpart.A microwave modulation link is demonstrated using our developed built-in push-pull acousto-optic modulator,which has the advantage of low power consumption.The nontrivial acousto-optic modulation performance benefits from the superior photoelastic property of the chalcogenide membrane and the completely bidirectional participation of the antisymmetric Rayleigh surface acoustic wave mode excited by the impedance-matched interdigital transducer,overcoming the issue of low modulation efficiency induced by the incoordinate energy attenuation of acoustic waves applied to the Mach-Zehnder interferometer with two arms in traditional push-pull acousto-optic modulators.
