Miniaturized spectrometers have been widely researched in recent years,but few studies are conducted with on-chip multimode schemes for mode-division multiplexing(MDM)systems.Here we propose an ultracompact mode-divis...Miniaturized spectrometers have been widely researched in recent years,but few studies are conducted with on-chip multimode schemes for mode-division multiplexing(MDM)systems.Here we propose an ultracompact mode-division demultiplexing spectrometer that includes branched waveguide structures and graphene-based photodetectors,which realizes simultaneously spectral dispersing and light fields detecting.In the bandwidth of 1500-1600 nm,the designed spectrometer achieves the single-mode spectral resolution of 7 nm for each mode of TE_(1)-TE_(4) by Tikhonov regularization optimization.Empowered by deep learning algorithms,the 15-nm resolution of parallel reconstruction for TE_(1)-TE_(4) is achieved by a single-shot measurement.Moreover,by stacking the multimode response in TE_(1)-TE_(4) to the single spectra,the 3-nm spectral resolution is realized.This design reveals an effective solution for on-chip MDM spectroscopy,and may find applications in multimode sensing,interconnecting and processing.展开更多
The demultiplexing experiment from a 40 Gb/s optical time-division multiplexing signal is completed by using electro- absorption sampling window based on electronic phase-locked loop circuit for clock recovery. Error-...The demultiplexing experiment from a 40 Gb/s optical time-division multiplexing signal is completed by using electro- absorption sampling window based on electronic phase-locked loop circuit for clock recovery. Error-free demultiplexing is achieved when the launched optical power into electro-absorption sampling window reaches 5.5 dBm without optical filter following the EDFA.展开更多
Wavelength demultiplexing waveguide couplers have important applications in integrated nanophotonic devices. Two of the most important indicators of the quality of a wavelength demultiplexing coupler are coupling effi...Wavelength demultiplexing waveguide couplers have important applications in integrated nanophotonic devices. Two of the most important indicators of the quality of a wavelength demultiplexing coupler are coupling efficiency and splitting ratio. In this study, we utilize two asymmetric high-index dielectric nanoantennas directly positioned on top of a silicon-on insulator waveguide to realize a compact wavelength demultiplexing coupler in a communication band, which is based on the interference of the waveguide modes coupled by the two nanoantennas. We add a Au substrate for further increasing the coupling efficiency. This has constructive and destructive influences on the antenna＇s in-coupling efficiency owing to the Fabry-Perot（FP） resonance in the SiO2 layer. Therefore, we can realize a wavelength demultiplexing coupler with compact size and high coupling efficiency. This coupler has widespread applications in the areas of wavelength filters,on-chip signal processing, and integrated nanophotonic circuits.展开更多
We demonstrate the spectroscopy of incoherent light with subdiffraction resolution.In a proof-of-principle experiment,we analyze the spectrum of a pair of incoherent pointlike sources whose separation is below the dif...We demonstrate the spectroscopy of incoherent light with subdiffraction resolution.In a proof-of-principle experiment,we analyze the spectrum of a pair of incoherent pointlike sources whose separation is below the diffraction limit.The two sources mimic a planetary system,with a brighter source for the star and a dimmer one for the planet.Acquiring spectral information about the secondary source is difficult because the two images have a substantial overlap.This limitation is solved by leveraging a structured measurement based on spatial-mode demultiplexing,where light is first sorted in its Hermite–Gaussian components in the transverse field then measured by photon detection.This allows us to effectively decouple the photons coming from the two sources.An application is suggested to enhance the exoplanets’atmosphere spectroscopy.A number of experiments of super-resolution imaging based on spatial demultiplexing have been conducted in the past few years,with promising results.Here,for the first time to the best of our knowledge,we extend this concept to the domain of spectroscopy.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
We propose a mode demultiplexing hybrid(MDH) that integrates mode demultiplexing, local oscillator power splitting, and optical 90-deg mixing using multi-plane light conversion(MPLC). We demonstrate the realization of...We propose a mode demultiplexing hybrid(MDH) that integrates mode demultiplexing, local oscillator power splitting, and optical 90-deg mixing using multi-plane light conversion(MPLC). We demonstrate the realization of a three-mode MDH using four phase plates, one more than what is required for an MPLC-based mode demultiplexer, via numerical simulations. The performance of the three-mode MDH is comparable to that of commercial single-mode 90-deg hybrids. This multiple-functionality device enables simplification of the coherent optical front end of mode-division multiplexing receivers.展开更多
In this Letter, the effects of material/structure parameters of photonic crystal（Ph C） parallel waveguides on the coupling length are investigated. The results show that, increasing the effective relative permittivi...In this Letter, the effects of material/structure parameters of photonic crystal（Ph C） parallel waveguides on the coupling length are investigated. The results show that, increasing the effective relative permittivity of the Ph C leads to a downward shift of the photonic bandgap and a variation of the coupling length. A compact Ph C 1.31/1.55 μm wavelength division multiplexer（WDM）/demultiplexer with simple structure is proposed,where the output power ratios are more than 24 d B. This WDM can multiplex/demultiplex other light waves efficiently.展开更多
An improved optoelectronic oscillator scheme for an optical time division multiplexing （OTDM） system based on cascaded Mach-Zehnder modulator （MZM） and polarization modulator （PolM） is experimentally investigate...An improved optoelectronic oscillator scheme for an optical time division multiplexing （OTDM） system based on cascaded Mach-Zehnder modulator （MZM） and polarization modulator （PolM） is experimentally investigated. The system can simultaneously realize clock recovery and demultiplexing. With the MZM working at peak point to generate return-to-zero-33 optical pulses and the PolM working as an equivalent intensity modulator, a high-quality clock signal with 35-fs timing jitter is extracted from the 160-GBaud OTDM-differential quaternary phase-shift keying signal. Narrow short optical switch gates （4 ps） are also generated to demultiplex 160-GBaud signals to 40-GBaud signals. Error-free performance is achieved with 2.4-dB power penalty in the worst case.展开更多
In order to increase the multiplexing density of the fiber Bragg gratings （FBGs） for a low cost per-sensor, based on the analysis of the spectrum shadow distortion （SSD）, a novel successive demultiplexing scheme f...In order to increase the multiplexing density of the fiber Bragg gratings （FBGs） for a low cost per-sensor, based on the analysis of the spectrum shadow distortion （SSD）, a novel successive demultiplexing scheme for FBG sensors has been developed. It is based on the optical cade division multiple access （CDMA） balanced demodulation. A high-density multiplexing-demultiplexing system for FBG sensors has been designed, and corresponding simulation carried out has demonstrated that the FBG sensors＇ reflective signals can still be obtained accurately and respectively, even if FBG sensors＇ operating bandwidths heavily overlap. The SSD has been greatly mitigated.展开更多
We propose a new type of wavelength division demultiplexer composed of a photonic crystal waveguide with asymmetric corrugated exit surface. The focus displacement for different symmetric corrugated surfaces is relati...We propose a new type of wavelength division demultiplexer composed of a photonic crystal waveguide with asymmetric corrugated exit surface. The focus displacement for different symmetric corrugated surfaces is relative to the intensity of the excited surface mode. By systematically investigating the effects of the parameters of the corrugated surface on the focus shift, we demonstrate an on-axis focus by a photonic crystal waveguide with an asymmetric corrugated exit surface at a specific wavelength. The precise equivalences of surface modes at each side of the exit surface are broken. Thus, for the light source with other wavelengths, the emerging beams are off-axis focused at different directions, similar to the function of a wavelength division demultiplexer.展开更多
A flexible polarization demultiplexing method based on an adaptive Kalman filter（AKF） is proposed in which the process noise covariance has been estimated adaptively. The proposed method may significantly improve th...A flexible polarization demultiplexing method based on an adaptive Kalman filter（AKF） is proposed in which the process noise covariance has been estimated adaptively. The proposed method may significantly improve the adaptive capability of an extended Kalman filter（EKF） by adaptively estimating the unknown process noise covariance. Compared to the conventional EKF, the proposed method can avoid the tedious and time consuming parameter-by-parameter tuning operations. The effectiveness of this method is confirmed experimentally in 128 Gb/s 16 QAM polarization-division-multiplexing（PDM） coherent optical transmission systems. The results illustrate that our proposed AKF has a better tracking accuracy and a faster convergence（about 4 times quicker）compared to a conventional algorithm with optimal process noise covariance.展开更多
A demultiplexing scheme based on semiconductor optical amplifier（SOA）and optical filter for optical time division multiplexing differential quadrature phase shift keying（OTDM-DQPSK）system is proposed and investiga...A demultiplexing scheme based on semiconductor optical amplifier（SOA）and optical filter for optical time division multiplexing differential quadrature phase shift keying（OTDM-DQPSK）system is proposed and investigated experimentally.With only a common half baudrate electrical clock modulated 33%duty cycle return-to-zero（RZ-33）optical clock signal as pump,this scheme is cost-effective,energy-efficient,and integration-potential.A proof-of-concept experiment is carried out for the demultiplexing of a 2×40-GBd OTDM-DQPSK signal.Error-free performance is demonstrated,and the average power penalty for both channels is about 3 dB.展开更多
Multiplexing across donors has emerged as a popular strategy to increase throughput,reduce costs,overcome technical batch effects,and improve doublet detection in single-cell genomic studies.To eliminate additional ex...Multiplexing across donors has emerged as a popular strategy to increase throughput,reduce costs,overcome technical batch effects,and improve doublet detection in single-cell genomic studies.To eliminate additional experimental steps,endogenous nuclear genome variants are used for demultiplexing pooled single-cell RNA sequencing(scRNA-seq)data by several computational tools.However,these tools have limitations when applied to single-cell sequencing methods that do not cover nuclear genomic regions well,such as single-cell assay for transposase-accessible chromatin with sequencing(scATAC-seq).Here,we demonstrate that mitochondrial germline variants are an alternative,robust,and computationally efficient endogenous barcode for sample demultiplexing.We propose MitoSort,a tool that uses mitochondrial germline variants to assign cells to their donor origins and identify cross-genotype doublets in single-cell genomic datasets.We evaluate its performance by using in silico pooled mitochondrial scATAC-seq(mtscATAC-seq)libraries and experimentally multiplexed data with cell hashtags.MitoSort achieves high accuracy and efficiency in genotype clustering and doublet detection for mtscATAC-seq data,addressing the limitations of current computational techniques tailored for scRNA-seq data.Moreover,MitoSort exhibits versatility,and can be applied to various single-cell sequencing approaches beyond mtscATAC-seq provided that the mitochondrial variants are reliably detected.Furthermore,we demonstrate the application of MitoSort in a case study where B cells from eight donors were pooled and assayed by single-cell multi-omics sequencing.Altogether,our results demonstrate the accuracy and efficiency of MitoSort,which enables reliable sample demultiplexing in various single-cell genomic applications.MitoSort is available at https://github.com/tangzhj/MitoSort.展开更多
A new all optical demultiplexer based on nonlinear effect in semiconductor laser amplifier (SLA) is proposed. It can demultiplex all channels of the OTDM signal concurrently, and it can also be integrated on ...A new all optical demultiplexer based on nonlinear effect in semiconductor laser amplifier (SLA) is proposed. It can demultiplex all channels of the OTDM signal concurrently, and it can also be integrated on a single chip. The proposed device consists of a series short Fabry Perot amplifiers (FPSLA) setting on the path vertically, through which the preamplified optical signal travels. Perpendicularly to the signal, K(channel number) paralleled beams of light pulse, which act as probes with repetition at the bit rate of one channel, irradiate on these FP SLAs , respectively, just when the corresponding signal channel pulse passes through the active region from lateral side. The transmissivity depends on the signal pulse. Theoretical analysis has been given. As a demonstrating example, a device operated at the speed of 25Gbit/s (2.5Gbit/s×10 ) is simulated and the results show that the about 9.24 dB extinction ratio can be achieved easily.展开更多
We proposed and demonstrated the ultra-compact 1310/1550 nm wavelength multiplexer/demultiplexer assisted by subwavelength grating(SWG)using particle swarm optimization(PSO)algorithm in silicon-on-insulator(SOI)platfo...We proposed and demonstrated the ultra-compact 1310/1550 nm wavelength multiplexer/demultiplexer assisted by subwavelength grating(SWG)using particle swarm optimization(PSO)algorithm in silicon-on-insulator(SOI)platform.Through the self-imaging effect of multimode interference(MMI)coupler,the demultiplexing function for 1310 nm and 1550 nm wavelengths is implemented.After that,three parallel SWG-based slots are inserted into the MMI section so that the effective refractive index of the modes can be engineered and thus the beat length can be adjusted.Importantly,these three SWG slots significantly reduce the length of the device,which is much shorter than the length of traditional MMI-based wavelength demultiplexers.Ultimately,by using the PSO algorithm,the equivalent refractive index and width of the SWG in a certain range are optimized to achieve the best performance of the wavelength demultiplexer.It has been verified that the device footprint is only 2×30.68μm^(2),and 1 dB bandwidths of larger than 120 nm are acquired at 1310 nm and 1550 nm wavelengths.Meanwhile,the transmitted spectrum shows that the insertion loss(IL)values are below 0.47 dB at both wavelengths when the extinction ratio(ER)values are above 12.65 dB.This inverse design approach has been proved to be efficient in increasing bandwidth and reducing device length.展开更多
A high integrated monolithic IC, with functions of clock recovery, data decision, and 1 ： 4 demultiplexer,is implemented in 0.25μm CMOS process for 2.5Gb/s fiber-optic communications. The recovered and frequency div...A high integrated monolithic IC, with functions of clock recovery, data decision, and 1 ： 4 demultiplexer,is implemented in 0.25μm CMOS process for 2.5Gb/s fiber-optic communications. The recovered and frequency divided 625MHz clock has a phase noise of -106.26dBc/Hz at 100kHz offset in response to a 2.5Gb/s PRBS input data （2^31-1）. The 2.5Gb/s PRBS data are demultiplexed to four 625Mb/s data. The 0.97mm× 0.97mm IC consumes 550mW under a single 3.3V power supply （not including output buffers）.展开更多
A 1 ：2 demultiplexer is designed and realized in standard 0. 18μm CMOS technology. A novel high-speed and low-voltage latch is used to realize the core circuit cell. Compared to the traditional source-coupled FET lo...A 1 ：2 demultiplexer is designed and realized in standard 0. 18μm CMOS technology. A novel high-speed and low-voltage latch is used to realize the core circuit cell. Compared to the traditional source-coupled FET logic structure latch, its power supply voltage is lower and the speed is faster. In addition, the negative feedback is used in the buffer circuit to widen its bandwidth. Measurement results show that the chip can work at the data rate of 20Gb/ s. The supply voltage is 1.8V and the current,including the buffer circuit, is 72mA.展开更多
As the combining form of the orthogonal frequency-division multiplexing (OFDM) technique and the vertical Bell Labs layered space-time (V-BLAST) architecture, the V-BLAST OFDM system can better meet the demand of next...As the combining form of the orthogonal frequency-division multiplexing (OFDM) technique and the vertical Bell Labs layered space-time (V-BLAST) architecture, the V-BLAST OFDM system can better meet the demand of next-generation (NextG) broadband mobile wireless multimedia communications. The symbols detection problem of the V-BLAST OFDM system is investigated under the frequency-selective fading environment. The joint space-frequency demultiplexing operation is proposed in the V-BLAST OFDM system. Successively, one novel half-rate rotational invariance joint space-frequency coding scheme for the V-BLAST OFDM system is proposed. By elegantly exploiting the above rotational invariance property, we derive one direct symbols detection scheme without knowing channels state information (CSI) for the frequency-selective V-BLAST OFDM system. Extensive simulation results demonstrate the validity of the novel half-rate rotational invariance joint space-frequency coding scheme and the performance of the direct symbols detection scheme.展开更多
An 8×2.5Gb/s 100km optical time division multiplexing(OTDM) experiment system is reported, which employs an electrical filter with high Q value for clock extraction, a nonlinear optical loop mirror(NOLM) for demu...An 8×2.5Gb/s 100km optical time division multiplexing(OTDM) experiment system is reported, which employs an electrical filter with high Q value for clock extraction, a nonlinear optical loop mirror(NOLM) for demultiplering and chirped fiber grating for dispersion compensation. The error free operation is achieved and the experiment results are given.展开更多
We in this paper propose a model to increase the diffraction efficiency of a holographic grating at 1550 nm for multiplexing application. To use such a grating, polarization dependence loss is introduced analytically ...We in this paper propose a model to increase the diffraction efficiency of a holographic grating at 1550 nm for multiplexing application. To use such a grating, polarization dependence loss is introduced analytically and then optimized for its minimum value A configuration of holographic grating is proposed based on both maximum diffraction efficiency and minimum polarization dependence loss. The proposed grating is expected to find importance in optoelectronic multichip module.展开更多
基金supported by the National Natural Science Foundation of China(Grants No.62005231)Fundamental Research Funds for the Central Universities(20720210045,20720200074)Guangdong Basic and Applied Basic Research Foundation(2021A1515012199).
文摘Miniaturized spectrometers have been widely researched in recent years,but few studies are conducted with on-chip multimode schemes for mode-division multiplexing(MDM)systems.Here we propose an ultracompact mode-division demultiplexing spectrometer that includes branched waveguide structures and graphene-based photodetectors,which realizes simultaneously spectral dispersing and light fields detecting.In the bandwidth of 1500-1600 nm,the designed spectrometer achieves the single-mode spectral resolution of 7 nm for each mode of TE_(1)-TE_(4) by Tikhonov regularization optimization.Empowered by deep learning algorithms,the 15-nm resolution of parallel reconstruction for TE_(1)-TE_(4) is achieved by a single-shot measurement.Moreover,by stacking the multimode response in TE_(1)-TE_(4) to the single spectra,the 3-nm spectral resolution is realized.This design reveals an effective solution for on-chip MDM spectroscopy,and may find applications in multimode sensing,interconnecting and processing.
基金supported by National 863 High TechnologyProjects of China (No. 2007AA01Z258, 2008AA01Z15)National Natural Science Foundation of China (No.60577034, 60747002,60877042)Science Foundation of Beijing(No.4062027).
文摘The demultiplexing experiment from a 40 Gb/s optical time-division multiplexing signal is completed by using electro- absorption sampling window based on electronic phase-locked loop circuit for clock recovery. Error-free demultiplexing is achieved when the launched optical power into electro-absorption sampling window reaches 5.5 dBm without optical filter following the EDFA.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0205700 and 2015CB932403)the National Natural Science Foundation of China(Grant Nos.11174062,51472057,and 21790364)
文摘Wavelength demultiplexing waveguide couplers have important applications in integrated nanophotonic devices. Two of the most important indicators of the quality of a wavelength demultiplexing coupler are coupling efficiency and splitting ratio. In this study, we utilize two asymmetric high-index dielectric nanoantennas directly positioned on top of a silicon-on insulator waveguide to realize a compact wavelength demultiplexing coupler in a communication band, which is based on the interference of the waveguide modes coupled by the two nanoantennas. We add a Au substrate for further increasing the coupling efficiency. This has constructive and destructive influences on the antenna＇s in-coupling efficiency owing to the Fabry-Perot（FP） resonance in the SiO2 layer. Therefore, we can realize a wavelength demultiplexing coupler with compact size and high coupling efficiency. This coupler has widespread applications in the areas of wavelength filters,on-chip signal processing, and integrated nanophotonic circuits.
基金European Commission (PE0000023-NQSTI)Ministero dell'Universitàe della Ricerca (QUEXO2022NZP4T3)Italian Space Agency (Subdiffraction Quantum Imaging SQI 2023-13-HH.0)。
文摘We demonstrate the spectroscopy of incoherent light with subdiffraction resolution.In a proof-of-principle experiment,we analyze the spectrum of a pair of incoherent pointlike sources whose separation is below the diffraction limit.The two sources mimic a planetary system,with a brighter source for the star and a dimmer one for the planet.Acquiring spectral information about the secondary source is difficult because the two images have a substantial overlap.This limitation is solved by leveraging a structured measurement based on spatial-mode demultiplexing,where light is first sorted in its Hermite–Gaussian components in the transverse field then measured by photon detection.This allows us to effectively decouple the photons coming from the two sources.An application is suggested to enhance the exoplanets’atmosphere spectroscopy.A number of experiments of super-resolution imaging based on spatial demultiplexing have been conducted in the past few years,with promising results.Here,for the first time to the best of our knowledge,we extend this concept to the domain of spectroscopy.
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Army Research Office(ARO)(W911NF1710500,W911NF1710553)
文摘We propose a mode demultiplexing hybrid(MDH) that integrates mode demultiplexing, local oscillator power splitting, and optical 90-deg mixing using multi-plane light conversion(MPLC). We demonstrate the realization of a three-mode MDH using four phase plates, one more than what is required for an MPLC-based mode demultiplexer, via numerical simulations. The performance of the three-mode MDH is comparable to that of commercial single-mode 90-deg hybrids. This multiple-functionality device enables simplification of the coherent optical front end of mode-division multiplexing receivers.
基金supported by the National Natural Science Foundation of China(No.61405058)the Hunan Provincial Natural Science Foundation of China(No.2017JJ2048)the Fundamental Research Funds for the Central Universities(No.531107050979)
文摘In this Letter, the effects of material/structure parameters of photonic crystal（Ph C） parallel waveguides on the coupling length are investigated. The results show that, increasing the effective relative permittivity of the Ph C leads to a downward shift of the photonic bandgap and a variation of the coupling length. A compact Ph C 1.31/1.55 μm wavelength division multiplexer（WDM）/demultiplexer with simple structure is proposed,where the output power ratios are more than 24 d B. This WDM can multiplex/demultiplex other light waves efficiently.
基金partly supported by the National"863"Program of China(No.2012AA011303)the National"973"Program of China(No.2011CB301702)+2 种基金the National Natural Science Foundation of China(Nos.61001121,60932004,and 61006041)the Fundamental Research Funds for the Central UniversitiesBUPT Excellent Ph.D.Students Foundation(No.CX201222)
文摘An improved optoelectronic oscillator scheme for an optical time division multiplexing （OTDM） system based on cascaded Mach-Zehnder modulator （MZM） and polarization modulator （PolM） is experimentally investigated. The system can simultaneously realize clock recovery and demultiplexing. With the MZM working at peak point to generate return-to-zero-33 optical pulses and the PolM working as an equivalent intensity modulator, a high-quality clock signal with 35-fs timing jitter is extracted from the 160-GBaud OTDM-differential quaternary phase-shift keying signal. Narrow short optical switch gates （4 ps） are also generated to demultiplex 160-GBaud signals to 40-GBaud signals. Error-free performance is achieved with 2.4-dB power penalty in the worst case.
基金supported by the Harbin Science Research Foundation under Grant No.2003AFQXJ004
文摘In order to increase the multiplexing density of the fiber Bragg gratings （FBGs） for a low cost per-sensor, based on the analysis of the spectrum shadow distortion （SSD）, a novel successive demultiplexing scheme for FBG sensors has been developed. It is based on the optical cade division multiple access （CDMA） balanced demodulation. A high-density multiplexing-demultiplexing system for FBG sensors has been designed, and corresponding simulation carried out has demonstrated that the FBG sensors＇ reflective signals can still be obtained accurately and respectively, even if FBG sensors＇ operating bandwidths heavily overlap. The SSD has been greatly mitigated.
基金supported by the Hunan Provincial Natural Science Foundation of China(No.08JJ3121)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20090161120029)
文摘We propose a new type of wavelength division demultiplexer composed of a photonic crystal waveguide with asymmetric corrugated exit surface. The focus displacement for different symmetric corrugated surfaces is relative to the intensity of the excited surface mode. By systematically investigating the effects of the parameters of the corrugated surface on the focus shift, we demonstrate an on-axis focus by a photonic crystal waveguide with an asymmetric corrugated exit surface at a specific wavelength. The precise equivalences of surface modes at each side of the exit surface are broken. Thus, for the light source with other wavelengths, the emerging beams are off-axis focused at different directions, similar to the function of a wavelength division demultiplexer.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.61335005,61325023,and 61401378)
文摘A flexible polarization demultiplexing method based on an adaptive Kalman filter（AKF） is proposed in which the process noise covariance has been estimated adaptively. The proposed method may significantly improve the adaptive capability of an extended Kalman filter（EKF） by adaptively estimating the unknown process noise covariance. Compared to the conventional EKF, the proposed method can avoid the tedious and time consuming parameter-by-parameter tuning operations. The effectiveness of this method is confirmed experimentally in 128 Gb/s 16 QAM polarization-division-multiplexing（PDM） coherent optical transmission systems. The results illustrate that our proposed AKF has a better tracking accuracy and a faster convergence（about 4 times quicker）compared to a conventional algorithm with optimal process noise covariance.
基金supported by the National"973"Program of China(No.2011CB301702)the National Natural Science Foundation of China(Nos.61001121,61006041,60736036,and 60932004)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education(No.200800131007)the Fundamental Research Funds for the Central Universities(No.2009CZ05)
文摘A demultiplexing scheme based on semiconductor optical amplifier（SOA）and optical filter for optical time division multiplexing differential quadrature phase shift keying（OTDM-DQPSK）system is proposed and investigated experimentally.With only a common half baudrate electrical clock modulated 33%duty cycle return-to-zero（RZ-33）optical clock signal as pump,this scheme is cost-effective,energy-efficient,and integration-potential.A proof-of-concept experiment is carried out for the demultiplexing of a 2×40-GBd OTDM-DQPSK signal.Error-free performance is demonstrated,and the average power penalty for both channels is about 3 dB.
基金supported by the National Key R&D Program of China(Grant No.2021YFA1102100)the National Natural Science Foundation of China(Grant Nos.32070644,32293190,32293191)to JX,and the Guangzhou Key Research and Development Program(Grant No.2023B03J1347)to YS and JX.
文摘Multiplexing across donors has emerged as a popular strategy to increase throughput,reduce costs,overcome technical batch effects,and improve doublet detection in single-cell genomic studies.To eliminate additional experimental steps,endogenous nuclear genome variants are used for demultiplexing pooled single-cell RNA sequencing(scRNA-seq)data by several computational tools.However,these tools have limitations when applied to single-cell sequencing methods that do not cover nuclear genomic regions well,such as single-cell assay for transposase-accessible chromatin with sequencing(scATAC-seq).Here,we demonstrate that mitochondrial germline variants are an alternative,robust,and computationally efficient endogenous barcode for sample demultiplexing.We propose MitoSort,a tool that uses mitochondrial germline variants to assign cells to their donor origins and identify cross-genotype doublets in single-cell genomic datasets.We evaluate its performance by using in silico pooled mitochondrial scATAC-seq(mtscATAC-seq)libraries and experimentally multiplexed data with cell hashtags.MitoSort achieves high accuracy and efficiency in genotype clustering and doublet detection for mtscATAC-seq data,addressing the limitations of current computational techniques tailored for scRNA-seq data.Moreover,MitoSort exhibits versatility,and can be applied to various single-cell sequencing approaches beyond mtscATAC-seq provided that the mitochondrial variants are reliably detected.Furthermore,we demonstrate the application of MitoSort in a case study where B cells from eight donors were pooled and assayed by single-cell multi-omics sequencing.Altogether,our results demonstrate the accuracy and efficiency of MitoSort,which enables reliable sample demultiplexing in various single-cell genomic applications.MitoSort is available at https://github.com/tangzhj/MitoSort.
文摘A new all optical demultiplexer based on nonlinear effect in semiconductor laser amplifier (SLA) is proposed. It can demultiplex all channels of the OTDM signal concurrently, and it can also be integrated on a single chip. The proposed device consists of a series short Fabry Perot amplifiers (FPSLA) setting on the path vertically, through which the preamplified optical signal travels. Perpendicularly to the signal, K(channel number) paralleled beams of light pulse, which act as probes with repetition at the bit rate of one channel, irradiate on these FP SLAs , respectively, just when the corresponding signal channel pulse passes through the active region from lateral side. The transmissivity depends on the signal pulse. Theoretical analysis has been given. As a demonstrating example, a device operated at the speed of 25Gbit/s (2.5Gbit/s×10 ) is simulated and the results show that the about 9.24 dB extinction ratio can be achieved easily.
基金supported by the National Natural Science Foundation of China(No.61505160)the Innovation Capability Support Program of Shaanxi(No.2018KJXX-042)+2 种基金the Natural Science Basic Research Program of Shaanxi(No.2019JM-084)the State Key Laboratory of Transient Optics and Photonics(No.SKLST202108)the Graduate Innovation and Practical Ability Training Project of Xi’an Shiyou University(No.YCS22213190)。
文摘We proposed and demonstrated the ultra-compact 1310/1550 nm wavelength multiplexer/demultiplexer assisted by subwavelength grating(SWG)using particle swarm optimization(PSO)algorithm in silicon-on-insulator(SOI)platform.Through the self-imaging effect of multimode interference(MMI)coupler,the demultiplexing function for 1310 nm and 1550 nm wavelengths is implemented.After that,three parallel SWG-based slots are inserted into the MMI section so that the effective refractive index of the modes can be engineered and thus the beat length can be adjusted.Importantly,these three SWG slots significantly reduce the length of the device,which is much shorter than the length of traditional MMI-based wavelength demultiplexers.Ultimately,by using the PSO algorithm,the equivalent refractive index and width of the SWG in a certain range are optimized to achieve the best performance of the wavelength demultiplexer.It has been verified that the device footprint is only 2×30.68μm^(2),and 1 dB bandwidths of larger than 120 nm are acquired at 1310 nm and 1550 nm wavelengths.Meanwhile,the transmitted spectrum shows that the insertion loss(IL)values are below 0.47 dB at both wavelengths when the extinction ratio(ER)values are above 12.65 dB.This inverse design approach has been proved to be efficient in increasing bandwidth and reducing device length.
文摘A high integrated monolithic IC, with functions of clock recovery, data decision, and 1 ： 4 demultiplexer,is implemented in 0.25μm CMOS process for 2.5Gb/s fiber-optic communications. The recovered and frequency divided 625MHz clock has a phase noise of -106.26dBc/Hz at 100kHz offset in response to a 2.5Gb/s PRBS input data （2^31-1）. The 2.5Gb/s PRBS data are demultiplexed to four 625Mb/s data. The 0.97mm× 0.97mm IC consumes 550mW under a single 3.3V power supply （not including output buffers）.
文摘A 1 ：2 demultiplexer is designed and realized in standard 0. 18μm CMOS technology. A novel high-speed and low-voltage latch is used to realize the core circuit cell. Compared to the traditional source-coupled FET logic structure latch, its power supply voltage is lower and the speed is faster. In addition, the negative feedback is used in the buffer circuit to widen its bandwidth. Measurement results show that the chip can work at the data rate of 20Gb/ s. The supply voltage is 1.8V and the current,including the buffer circuit, is 72mA.
文摘As the combining form of the orthogonal frequency-division multiplexing (OFDM) technique and the vertical Bell Labs layered space-time (V-BLAST) architecture, the V-BLAST OFDM system can better meet the demand of next-generation (NextG) broadband mobile wireless multimedia communications. The symbols detection problem of the V-BLAST OFDM system is investigated under the frequency-selective fading environment. The joint space-frequency demultiplexing operation is proposed in the V-BLAST OFDM system. Successively, one novel half-rate rotational invariance joint space-frequency coding scheme for the V-BLAST OFDM system is proposed. By elegantly exploiting the above rotational invariance property, we derive one direct symbols detection scheme without knowing channels state information (CSI) for the frequency-selective V-BLAST OFDM system. Extensive simulation results demonstrate the validity of the novel half-rate rotational invariance joint space-frequency coding scheme and the performance of the direct symbols detection scheme.
文摘An 8×2.5Gb/s 100km optical time division multiplexing(OTDM) experiment system is reported, which employs an electrical filter with high Q value for clock extraction, a nonlinear optical loop mirror(NOLM) for demultiplering and chirped fiber grating for dispersion compensation. The error free operation is achieved and the experiment results are given.
文摘We in this paper propose a model to increase the diffraction efficiency of a holographic grating at 1550 nm for multiplexing application. To use such a grating, polarization dependence loss is introduced analytically and then optimized for its minimum value A configuration of holographic grating is proposed based on both maximum diffraction efficiency and minimum polarization dependence loss. The proposed grating is expected to find importance in optoelectronic multichip module.
