Graphene’s unique photothermoelectric(PTE)effect,combined with its compatibility for on-chip fabrication,promises its development in chip-integrated photodetectors with ultralow dark-current and ultrafast speed.Previ...Graphene’s unique photothermoelectric(PTE)effect,combined with its compatibility for on-chip fabrication,promises its development in chip-integrated photodetectors with ultralow dark-current and ultrafast speed.Previous designs of on-chip graphene photodetectors required external electrical biases or gate voltages to separate photocarriers,leading to increased power consumption and complex circuitry.Here,we demonstrate a nonvolatile graphene p–i–n homojunction constructed on a silicon photonic crystal waveguide,which facilitates PTE-based photodetection without the need for electrical bias or gate voltages.By designing an air-slotted photonic crystal waveguide as two individual silicon back gates and employing ferroelectric dielectrics with remnant polarization fields,the nonvolatile p–i–n homojunction with a clear gradient of Seebeck coefficient is electrically configured.Hot carriers in the graphene channel generated from the absorption of waveguide evanescent field are separated by the nonvolatile p–i–n homojunction effectively to yield considerable photocurrents.With zero-bias and zero-gate voltage,the nonvolatile graphene p–i–n homojunction photodetector integrated on the optical waveguide exhibits high and flat responsivity of 193 mAW^(−1)over the broadband wavelength range of 1560–1630 nm and an ultrafast dynamics bandwidth of 17 GHz measured in the limits of our instruments.With the high-performance on-chip photodetection,the nonvolatile graphene homojunction directly constructed on silicon photonic circuits promises the extended on-chip functions of the optoelectronic synapse,in-memory sensing and computing,and neuromorphic computing.展开更多
Free-space optical(FSO)communication technology is a promising approach to establish a secure wireless link,which has the advantages of excellent directionality,large bandwidth,multiple services,low mass and less powe...Free-space optical(FSO)communication technology is a promising approach to establish a secure wireless link,which has the advantages of excellent directionality,large bandwidth,multiple services,low mass and less power requirements,and easy and fast deployments.Increasing the communication capacity is the perennial goal in both scientific and engineer communities.In this paper,we experimentally demonstrate a Tbit/s parallel FSO communication system using a soliton microcomb as a multiple wavelength laser source.Two communication terminals are installed in two buildings with a straight-line distance of~1 km.102 comb lines are modulated by10 Gbit/s differential phase-shift keying signals and demodulated using a delay-line interferometer.When the transmitted optical power is amplified to 19.8 dBm,42 optical channels have optical signal-to-noise ratios higher than 27 dB and bit error rates less than 1×10^(-9).Our experiment shows the feasibility of a wavelength-division multiplexing FSO communication system which suits the ultra-high-speed wireless transmission application scenarios in future satellite-based communications,disaster recovery,defense,last mile problems in networks and remote sensing,and so on.展开更多
基金supported by the Key Research and Development Program(2022YFA1404800)the National Natural Science Foundation of China(12374359 and 62375225)+1 种基金the Shaanxi Fundamental Science Research Project for Mathematics and Physics(22JSY004)the Xi’an Science and Technology Plan Project(2023JH-ZCGJ-0023).
文摘Graphene’s unique photothermoelectric(PTE)effect,combined with its compatibility for on-chip fabrication,promises its development in chip-integrated photodetectors with ultralow dark-current and ultrafast speed.Previous designs of on-chip graphene photodetectors required external electrical biases or gate voltages to separate photocarriers,leading to increased power consumption and complex circuitry.Here,we demonstrate a nonvolatile graphene p–i–n homojunction constructed on a silicon photonic crystal waveguide,which facilitates PTE-based photodetection without the need for electrical bias or gate voltages.By designing an air-slotted photonic crystal waveguide as two individual silicon back gates and employing ferroelectric dielectrics with remnant polarization fields,the nonvolatile p–i–n homojunction with a clear gradient of Seebeck coefficient is electrically configured.Hot carriers in the graphene channel generated from the absorption of waveguide evanescent field are separated by the nonvolatile p–i–n homojunction effectively to yield considerable photocurrents.With zero-bias and zero-gate voltage,the nonvolatile graphene p–i–n homojunction photodetector integrated on the optical waveguide exhibits high and flat responsivity of 193 mAW^(−1)over the broadband wavelength range of 1560–1630 nm and an ultrafast dynamics bandwidth of 17 GHz measured in the limits of our instruments.With the high-performance on-chip photodetection,the nonvolatile graphene homojunction directly constructed on silicon photonic circuits promises the extended on-chip functions of the optoelectronic synapse,in-memory sensing and computing,and neuromorphic computing.
基金National Natural Science Foundation of China(62075238,61875227)National Key Research and Development Program of China(2022YFB2803203)。
文摘Free-space optical(FSO)communication technology is a promising approach to establish a secure wireless link,which has the advantages of excellent directionality,large bandwidth,multiple services,low mass and less power requirements,and easy and fast deployments.Increasing the communication capacity is the perennial goal in both scientific and engineer communities.In this paper,we experimentally demonstrate a Tbit/s parallel FSO communication system using a soliton microcomb as a multiple wavelength laser source.Two communication terminals are installed in two buildings with a straight-line distance of~1 km.102 comb lines are modulated by10 Gbit/s differential phase-shift keying signals and demodulated using a delay-line interferometer.When the transmitted optical power is amplified to 19.8 dBm,42 optical channels have optical signal-to-noise ratios higher than 27 dB and bit error rates less than 1×10^(-9).Our experiment shows the feasibility of a wavelength-division multiplexing FSO communication system which suits the ultra-high-speed wireless transmission application scenarios in future satellite-based communications,disaster recovery,defense,last mile problems in networks and remote sensing,and so on.
