Recently,high-performance thin-film lithium niobate optical modulators have emerged that,together with advanced multiplexing technologies,are highly expected to satisfy the ever-growing demand for high-capacity optica...Recently,high-performance thin-film lithium niobate optical modulators have emerged that,together with advanced multiplexing technologies,are highly expected to satisfy the ever-growing demand for high-capacity optical interconnects utilizing multiple channels.Accordingly,in this study,a compact lithium-niobate-on-insulator(LNOI)photonic chip was adopted to establish four-channel wavelength-division-multiplexing(WDM)transmitters,comprising four optical modulators based on ultracompact 2×2 Fabry-Perot cavities and a four-channel WDM filter based on multimode waveguide gratings.The fabricated chip with four wavelength channels has a total footprint as compact as 0.3×2.8 mm^(2),and exhibits an excess loss of~0.8 dB as well as low inter-channel crosstalk of<–22 dB.Using this LNOI photonic chip,high-capacity data transmissions of 320 Gbps(4×80 Gbps)on-off-keying signals and 400 Gbps(4×100 Gbps)four-level pulse amplitude signals were successfully realized with the ultra-low power consumption of 11.9 fJ/bit.展开更多
Modern optical communications rely heavily on dense wavelength-division multiplexing(DWDM)technology because of its capability of significantly increasing transmission channels.Here,we demonstrate,for the first time t...Modern optical communications rely heavily on dense wavelength-division multiplexing(DWDM)technology because of its capability of significantly increasing transmission channels.Here,we demonstrate,for the first time to the best of our knowledge,a compact photonic chip for DWDM transmitters on lithiumniobate-on-insulator(LNOI)by introducing the array of 2×2 Fabry–Perot(FP)cavity electro-optic(EO)modulators.A four-channel LNOI photonic chip for DWDM is designed and realized with a channel spacing of 1.6 nm(which is the narrowest one reported until now for LNOI optical transmitters),exhibiting a total excess loss of 1.3 dB and high 3-dB EO bandwidths of>67 GHz for all channels.Specifically,these four 2×2 FP cavities are designed with broadened LNOI photonic waveguides in the cavity sections,and they are placed very closely on the chip so that their resonance wavelengths are aligned precisely with the desired channelspacing of∼1.6 nm.Finally,the generation of 4×80-Gbps on–off keying and 4×100-Gbps PAM4 signals is demonstrated successfully with four channels,and the power consumption is as low as∼5.1 fJ∕bit.The present photonic chip has a compact footprint of about 0.78 mm×0.58 mm,showing great potential to work with more than four channels and to be very useful for future large-capacity optical links.展开更多
The performance of a wavelength-division multiplexing (WDM) free-space optical (FSO) commu-nication system in a turbulent atmosphere employing optical amplifiers to improve capacity is investigated, in the presence of...The performance of a wavelength-division multiplexing (WDM) free-space optical (FSO) commu-nication system in a turbulent atmosphere employing optical amplifiers to improve capacity is investigated, in the presence of amplified spontaneous emission noise, scintillation, beam spreading, atmospheric attenuation and interchannel crosstalk. Using on-off keying modulation, Monte Carlo simulation techniques are used to obtain the average bit error rate and system capability due to scintillation and the effect of introducing a power control algorithm (PCA) to the system is investigated. The PCA ensures that at any receiving instant, the same turbulence- free powers are received by all the receiving lenses. The performance of various WDM FSO communication system configurations such as non-amplified systems with an adaptive decision threshold (NOAADT), non- amplified systems with a non-adaptive decision threshold, fixed gain amplified systems with an adaptive decision threshold, fixed gain amplified systems with a non- adaptive decision threshold and saturated gain amplified systems with a non-adaptive decision threshold (SOA- NADT) are investigated. Results obtained show that the SOANADT is superior to the NOAADT and the PCA is only beneficial in amplified systems.展开更多
Multi-lane integrated transmitter chips are key components in future compact optical modules to realize high-speed optical interconnects.Thin-film lithium niobate(TFLN)photonics have emerged as a promising platform fo...Multi-lane integrated transmitter chips are key components in future compact optical modules to realize high-speed optical interconnects.Thin-film lithium niobate(TFLN)photonics have emerged as a promising platform for achieving high-performance chip-scale optical systems.Combining a coarse wavelength-division multiplexing(CWDM)devices using fabrication-tolerant angled multimode interferometer structure and high-performance electro-optical modulators,we demonstrate monolithic on-chip four-channel CWDM transmitter on the TFLN platform for the first time.The four-channel CWDM transmitter enables high-speed transmissions of 100 Gb/s data rate per wavelength channel(i.e.,an aggregated date rate of 400 Gb/s).展开更多
Latency sensitive services have attracted much attention lately and imposedstringent requirements on the access network design. Passive optical networks (PONs) providea potential long-term solution for the underlying ...Latency sensitive services have attracted much attention lately and imposedstringent requirements on the access network design. Passive optical networks (PONs) providea potential long-term solution for the underlying transport network supporting theseservices. This paper discusses latency limitations in PON and recent progress in PONstandardization to improve latency. Experimental results of a low latency PON system arepresented as a proof of concept.展开更多
A novel flat-top and low-dispersion optical interleaver using ring cavities （RCs） in a Mach-Zehnder interferometer （MZI） is proposed. It is composed of eight mirrors and two nested prism pairs. Each prism and the ...A novel flat-top and low-dispersion optical interleaver using ring cavities （RCs） in a Mach-Zehnder interferometer （MZI） is proposed. It is composed of eight mirrors and two nested prism pairs. Each prism and the two mirrors behave as a RC. Phase shift of RC is a periodic function of the frequency of the input light which acts as a phase dispersive mirror. The two phase shifts needed to achieve a flat-top spectral passband are provided by Fresnel reflectivities at the prism-air interface of the two RCs. The optimum interface reflectivities for flat passband, high isolation and low dispersion can be obtained only by choosing an appropriate material for the prism in each RC. The proposed interleaver in a 25 GHz channel spacing application exhibits a 0.5 dB passband greater than 24 GHz （96% of the spacing）, a 30 dB stopband greater than 21.2 GHz （84.8% of the spacing）, a channel isolation higher than 32 dB and chromatic dispersion ±50 ps/nm within the range of center-frequency ：t：2 GHz ITU passband.展开更多
A novel architecture of wavelength-division multiplexing/optical code division multiplexing access-passive optical network （WDM/OCDMA-PON） based on superstructure fiber Bragg grating （SSFBG） and wavelength re-modu...A novel architecture of wavelength-division multiplexing/optical code division multiplexing access-passive optical network （WDM/OCDMA-PON） based on superstructure fiber Bragg grating （SSFBG） and wavelength re-modulation technology is proposed. In this scheme, WDM is overlaid on OCDMA channel in a single network by virtue of a kind of SSFBC, and the total capacity of hybrid PON can be extended by regulating the transmission power reasonably. Re, modulation technology is also a good method to save wavelength-specific components at the optical network unit （ONU） and cost of wavelength management on the customer side. In simulation system, 1.25 Gb/s up/downstream data are transported with good performance. In addition the crosstalk penalties from adjacent wavelength channels （with the same OC） are found to be negligible in upstream and downstream transmissions.展开更多
In this paper,the sharing schemes of multicast in survivable Wavelength-Division Multi-plexed(WDM) networks are studied and the concept of Shared Risk Link Group(SRLG) is considered.While the network resources are sha...In this paper,the sharing schemes of multicast in survivable Wavelength-Division Multi-plexed(WDM) networks are studied and the concept of Shared Risk Link Group(SRLG) is considered.While the network resources are shared by the backup paths,the sharing way is possible to make the backup paths selfish.This selfishness leads the redundant hops of the backup route and a large number of primary lightpaths to share one backup link.The sharing schemes,especially,the self-sharing and cross-sharing,are investigated to avoid the selfishness when computing the backup light-tree.In order to decrease the selfishness of the backup paths,it is important to make the sharing links fair to be used.There is a trade-off between the self-sharing and cross-sharing,which is adjusted through simulation to adapt the sharing degree of each sharing scheme and save the network resources.展开更多
Recently, a tunable fiber Bragg grating(FBG) was developed by using stress-responsive colloidal crystals. In this paper, we have simulated the application of these nanoparticles into the super-structured fiber Bragg g...Recently, a tunable fiber Bragg grating(FBG) was developed by using stress-responsive colloidal crystals. In this paper, we have simulated the application of these nanoparticles into the super-structured fiber Bragg grating(SSFBG) written with perfect sequences derived from a short maximal-length sequence. A tunable SSFBG will be available to overcome the prohibitive temperature variation of the optical codecs. Nevertheless,we presented a method to implement coherent time spreading optical code-division multiple-access(OCDMA) where a unique code(or perfect sequence) can be reused and mixed with different wavelengths to obtain a tunable wavelength-division multiplexing(WDM)system. In order to maximize the binary throughput, we have selected a unique short maximal-length sequence composed of 7 chips that can be tuned with 7 different optical wavelengths. We found thousands of different tunable combinations that presented power contrast ratios(P/C) higher than 12 dB. When a WDM-OCDMA system used 2 different combinations simultaneously, the perfect binary detection with error correction codes was achieved successfully. The tunable SSFBG with colloidal crystals will be a simple and good alternative choice for fiber-to-the-home(FTTH) communications.展开更多
Nyquist wavelength-division multiplexing （N-WDM） allows high spectral efficiency （SE） in long-haul transmission systems. Compared to polarization-division multiplexing quadrature phase-shift keying （PDM-QPSK）, m...Nyquist wavelength-division multiplexing （N-WDM） allows high spectral efficiency （SE） in long-haul transmission systems. Compared to polarization-division multiplexing quadrature phase-shift keying （PDM-QPSK）, multilevel modulation, such as PDM 16 quadrature-amplitude modulation （16-QAM）, is much more sensitive to intrachannel noise and interchannel linear crosstalk caused by N-WDM. We experimentally generate and transmit a 6 x 128 Gbit/s N-WDM PDM 16-QAM signal over 1200 km single-mode fiber （SMF）-28 with amplification provided by an erbium-doped fiber amplifier （EDFA） only. The net SE is 7.47 bit/s/Hz, which to the best of our knowledge is the highest SE for a signal with a bit rate beyond 100 Gbit/s using the PDM 16-QAM. Such SE was achieved by DSP pre-equalization of transmitter-side impairments and DSP post-equalization of channel and receiver-side impairments. Nyquist-band can be used in pre-equalization to enhance the tolerance of PDM 16-QAM to aggressive spectral shaping. The bit-error ratio （BER） for each of the 6 channels is smaller than the forward error correction （FEC） limit of 3.8 × 10-3 after 1200 km SMF-28 transmission.展开更多
Proposed is an interference type of optical analog-to-digital conversion(ADC). The refractive index of Fabry-Perot cavity changes with different voltages. The Fabry-Perot resonator converts electronic intensity into l...Proposed is an interference type of optical analog-to-digital conversion(ADC). The refractive index of Fabry-Perot cavity changes with different voltages. The Fabry-Perot resonator converts electronic intensity into light wavelength through selecting lights of different wavelengthes. The parameters of the scheme are acquired with the transmission matrix of optical element and the time of steady-state light field. The maximum sampling speedes of 4-bit, 6-bit, 7-bit, 8-bit and 9-bit(ADC) are 1.695×1010 count/s, 4.33×109 count/s, 2.38×109 count/s, 1.24×109 count/s and 5.9×108 count/s, respectively.展开更多
Low-cost,flexible and intelligent optical performance monitoring and management is a key enabling technology for network quality guarantee,especially in the era of explosive growth of communication capacity and networ...Low-cost,flexible and intelligent optical performance monitoring and management is a key enabling technology for network quality guarantee,especially in the era of explosive growth of communication capacity and network scale.However,to the best of our knowledge,it is extremely challenging to implement real-time performance monitoring and operations,administration and maintenance(OAM) in a highly complex dynamic network.In this paper,we propose an innovative optical identification(OID) scheme that can realize both performance monitoring and some advanced OAM sub-functions.The basic concepts,applications,challenges and evolution directions of this OID tool are also discussed.展开更多
In order to realize broadband and high-speed transmission in the last mile access network,the Coded Wavelength-Division Multiplexing(Coded-WDM)technique on PON(so-called CDM-PON)is presented on fiber-to-the-home acces...In order to realize broadband and high-speed transmission in the last mile access network,the Coded Wavelength-Division Multiplexing(Coded-WDM)technique on PON(so-called CDM-PON)is presented on fiber-to-the-home access network.In this paper,the codcd-WDM coder/decoder(codec}is configured on Optical Network Unit(ONU)and Optical Line Terminal(OLT)in Ethemet Passive Optical Network(E-PON).Here,network codecs are constructed with Arrayed Waveguide Grating(AWG)devices and the signature address code is employed as complementary Walsh code whose original code is for data bit'1'and complementary code is for data bit'0'respectively.It is shown that the simultaneous active user of proposed scheme using CWH code is improved 100%than using M-Sequence and conventional Walsh code for given bit error rate of 10^-9.In addition,the signal to noise ratio(SNR)performance is improved by 6dB compared with conventional scheme employed M-sequence and Walsh code.展开更多
A high-performance silicon arrayed-waveguide grating(AWG)with 0.4-nm channel spacing for dense wavelength-division multiplexing systems is designed and realized successfully.The device design involves broadening the a...A high-performance silicon arrayed-waveguide grating(AWG)with 0.4-nm channel spacing for dense wavelength-division multiplexing systems is designed and realized successfully.The device design involves broadening the arrayed waveguides far beyond the single-mode regime,which minimizes random phase errors and propagation loss without requiring any additional fabrication steps.To further enhance performance,Euler bends have been incorporated into the arrayed waveguides to reduce the device’s physical footprint and suppress the excitation of higher modes.In addition,shallowly etched transition regions are introduced at the junctions between the free-propagation regions and the arrayed waveguides to minimize mode mismatch losses.As an example,a 32×32 AWG(de)multiplexer with a compact size of 900μm×2200μm is designed and demonstrated with a narrow channel spacing of 0.4 nm by utilizing 220-nm-thick silicon photonic waveguides.The measured excess loss for the central channel is∼0.65 dB,the channel nonuniformity is around 2.5 dB,while the adjacent-channel crosstalk of the central output port is−21.4 dB.To the best of our knowledge,this AWG(de)multiplexer is the best one among silicon-based implementations currently available,offering both dense channel spacing and a large number of channels.展开更多
In this paper,we demonstrate the single-fiber and two-wavelength time transfer(SFTWTT)over a 2061 km field fiber loopback link network with a synchronous wavelength-division and time-division multiplexing access(WD-TD...In this paper,we demonstrate the single-fiber and two-wavelength time transfer(SFTWTT)over a 2061 km field fiber loopback link network with a synchronous wavelength-division and time-division multiplexing access(WD-TDMA).This system utilizes wavelength-division multiplexing to avoid the impact of backscatter.In order to achieve high-precision time transfer,time-division multiplexing access is employed.This approach facilitates multiple bidirectional comparisons between local and remote devices.A digital phase-locked loop(PLL),which matches the bandwidth of the transfer system,and precision temperature control technology have been proposed to enhance the high stability of the fiber-optic time and frequency transfer system.The first on-site high-precision fiber-optic time transfer system exceeding 2000 km has been validated.Experimental results show that the stabilities of 5.6 ps@1 s and 3.1 ps@40,000 s can be achieved.The precision of time transfer over a 2061 km fiber-optic network,employing a single-fiber and two-wavelength approach,has been significantly enhanced.This study presents an average time difference of 52 ps across the distance,with a system uncertainty budgeted at 41.8 ps.This achievement signifies a substantial advancement in the realms of stability and reach for optical fiber time transfer,facilitating the development of a high-precision ground-based time service system.展开更多
In this paper, an overview of author＇s research is presented, commencing at the University of Kent under Prof. David A. Jackson. Early research in short optical pulses and fiber-optic delay-line digital correlators l...In this paper, an overview of author＇s research is presented, commencing at the University of Kent under Prof. David A. Jackson. Early research in short optical pulses and fiber-optic delay-line digital correlators led to optical communications research in code-division multiple access networking. This research was based on broadband incoherent light, and this theme continued with research into spectrum-sliced wavelength-division multiplexing. In shifting from photonics research to biomedical optics and biophotonics in the late 1990s, the emphasis on exploiting broadband light continued with research in optical coherence tomography, amongst other topics. In addition to the research outcomes, how these outcomes were attained is described, including mention of the exceptional contributions of many of my colleagues.展开更多
This paper proposes a dynamic RWA scheme using fuzzy logic control on IP/GMPLS over WDM networks to achieve the best quality of network transmission. The proposed algorithm dynamically allocates network resources and ...This paper proposes a dynamic RWA scheme using fuzzy logic control on IP/GMPLS over WDM networks to achieve the best quality of network transmission. The proposed algorithm dynamically allocates network resources and reserves partial bandwidth based on the current network status, which includes the request bandwidth, average utilization for each wavelength and its coefficient of variance （C.V.） of data traffic, to determine whether the connection can be set tip. Five fuzzy sets for request bandwidth, average rate and C.V. of data traffic are used to divide the variable space： very large （LP）, large （SP）, normal （ZE）, small （SN）, and very small （LN）. Setting the fuzzy limit is a key part in the proposed algorithm. The simulation of scenarios in this paper has two steps. In the first step, the adaptive fuzzy limits are evaluated based on average transmission cost pertaining to ten network statuses. The second step is to compare the proposed algorithm with periodic measurement of traffic （PMT） in ATM networks in six network situations to show that the proposed FC-RWA algorithm can provide better network transmission.展开更多
基金the National Major Research and Development Program(No.2018YFB2200200/2018YFB2200201)National Science Fund for Distinguished Young Scholars(61725503)+4 种基金National Natural Science Foundation of China(NSFC)(91950205,61961146003,92150302,62105283,62205286)Zhejiang Provincial Natural Science Foundation(LD19F050001)Zhejiang Provincial Major Research and Development Program(No.2021C01199)Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2021R01001)the Fundamental Research Funds for the Central Universities.The authors thank the Westlake Center for Micro/Nano Fabrication for the partial facility support。
文摘Recently,high-performance thin-film lithium niobate optical modulators have emerged that,together with advanced multiplexing technologies,are highly expected to satisfy the ever-growing demand for high-capacity optical interconnects utilizing multiple channels.Accordingly,in this study,a compact lithium-niobate-on-insulator(LNOI)photonic chip was adopted to establish four-channel wavelength-division-multiplexing(WDM)transmitters,comprising four optical modulators based on ultracompact 2×2 Fabry-Perot cavities and a four-channel WDM filter based on multimode waveguide gratings.The fabricated chip with four wavelength channels has a total footprint as compact as 0.3×2.8 mm^(2),and exhibits an excess loss of~0.8 dB as well as low inter-channel crosstalk of<–22 dB.Using this LNOI photonic chip,high-capacity data transmissions of 320 Gbps(4×80 Gbps)on-off-keying signals and 400 Gbps(4×100 Gbps)four-level pulse amplitude signals were successfully realized with the ultra-low power consumption of 11.9 fJ/bit.
基金supported by the National Key Research and Development Program of China(Grant Nos.2018YFB2200200 and 2018YFB2200201)the National Natural Science Foundation of China(NSFC)(Grant Nos.92150302,62135012,U23B2047,and 62321166651)+2 种基金the Zhejiang Provincial Natural Science Foundation(Grant No.LDT23F04012F05)the Zhejiang Provincial Key Research and Development Program(Grant No.2021C01199)the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(Grant No.2021R01001).
文摘Modern optical communications rely heavily on dense wavelength-division multiplexing(DWDM)technology because of its capability of significantly increasing transmission channels.Here,we demonstrate,for the first time to the best of our knowledge,a compact photonic chip for DWDM transmitters on lithiumniobate-on-insulator(LNOI)by introducing the array of 2×2 Fabry–Perot(FP)cavity electro-optic(EO)modulators.A four-channel LNOI photonic chip for DWDM is designed and realized with a channel spacing of 1.6 nm(which is the narrowest one reported until now for LNOI optical transmitters),exhibiting a total excess loss of 1.3 dB and high 3-dB EO bandwidths of>67 GHz for all channels.Specifically,these four 2×2 FP cavities are designed with broadened LNOI photonic waveguides in the cavity sections,and they are placed very closely on the chip so that their resonance wavelengths are aligned precisely with the desired channelspacing of∼1.6 nm.Finally,the generation of 4×80-Gbps on–off keying and 4×100-Gbps PAM4 signals is demonstrated successfully with four channels,and the power consumption is as low as∼5.1 fJ∕bit.The present photonic chip has a compact footprint of about 0.78 mm×0.58 mm,showing great potential to work with more than four channels and to be very useful for future large-capacity optical links.
文摘The performance of a wavelength-division multiplexing (WDM) free-space optical (FSO) commu-nication system in a turbulent atmosphere employing optical amplifiers to improve capacity is investigated, in the presence of amplified spontaneous emission noise, scintillation, beam spreading, atmospheric attenuation and interchannel crosstalk. Using on-off keying modulation, Monte Carlo simulation techniques are used to obtain the average bit error rate and system capability due to scintillation and the effect of introducing a power control algorithm (PCA) to the system is investigated. The PCA ensures that at any receiving instant, the same turbulence- free powers are received by all the receiving lenses. The performance of various WDM FSO communication system configurations such as non-amplified systems with an adaptive decision threshold (NOAADT), non- amplified systems with a non-adaptive decision threshold, fixed gain amplified systems with an adaptive decision threshold, fixed gain amplified systems with a non- adaptive decision threshold and saturated gain amplified systems with a non-adaptive decision threshold (SOA- NADT) are investigated. Results obtained show that the SOANADT is superior to the NOAADT and the PCA is only beneficial in amplified systems.
基金This work is supported partially by the National Major Research and Development Program(2019YFB1803902)National Natural Science Foundation of China(NSFC)(62135012,62105107)+3 种基金Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2021R01001)Guangdong Basic and Applied Basic Research Foundation(2021A 1515012215,2021B1515120057)Science and Technology Planning Project of Guangdong Province(2019A050510039)Fundamental Research Funds for the Central Universities(2021QNA5001).
文摘Multi-lane integrated transmitter chips are key components in future compact optical modules to realize high-speed optical interconnects.Thin-film lithium niobate(TFLN)photonics have emerged as a promising platform for achieving high-performance chip-scale optical systems.Combining a coarse wavelength-division multiplexing(CWDM)devices using fabrication-tolerant angled multimode interferometer structure and high-performance electro-optical modulators,we demonstrate monolithic on-chip four-channel CWDM transmitter on the TFLN platform for the first time.The four-channel CWDM transmitter enables high-speed transmissions of 100 Gb/s data rate per wavelength channel(i.e.,an aggregated date rate of 400 Gb/s).
文摘Latency sensitive services have attracted much attention lately and imposedstringent requirements on the access network design. Passive optical networks (PONs) providea potential long-term solution for the underlying transport network supporting theseservices. This paper discusses latency limitations in PON and recent progress in PONstandardization to improve latency. Experimental results of a low latency PON system arepresented as a proof of concept.
基金Projet supported by the National Natural Science Foundation of China (Grant No.10804070)the Innovation Program of Education Commission of Shanghai Municipality (Grant No.09YZ06)the Shanghai Leading Academic Discipline Project (Grant No.S30108)
文摘A novel flat-top and low-dispersion optical interleaver using ring cavities （RCs） in a Mach-Zehnder interferometer （MZI） is proposed. It is composed of eight mirrors and two nested prism pairs. Each prism and the two mirrors behave as a RC. Phase shift of RC is a periodic function of the frequency of the input light which acts as a phase dispersive mirror. The two phase shifts needed to achieve a flat-top spectral passband are provided by Fresnel reflectivities at the prism-air interface of the two RCs. The optimum interface reflectivities for flat passband, high isolation and low dispersion can be obtained only by choosing an appropriate material for the prism in each RC. The proposed interleaver in a 25 GHz channel spacing application exhibits a 0.5 dB passband greater than 24 GHz （96% of the spacing）, a 30 dB stopband greater than 21.2 GHz （84.8% of the spacing）, a channel isolation higher than 32 dB and chromatic dispersion ±50 ps/nm within the range of center-frequency ：t：2 GHz ITU passband.
基金Project supported by the Shanghai Leading Academic Discipline Project (Grant No.S30108)the Science and Technology Commission of Shanghai Municipality (Grant No.08DZ2231100)
文摘A novel architecture of wavelength-division multiplexing/optical code division multiplexing access-passive optical network （WDM/OCDMA-PON） based on superstructure fiber Bragg grating （SSFBG） and wavelength re-modulation technology is proposed. In this scheme, WDM is overlaid on OCDMA channel in a single network by virtue of a kind of SSFBC, and the total capacity of hybrid PON can be extended by regulating the transmission power reasonably. Re, modulation technology is also a good method to save wavelength-specific components at the optical network unit （ONU） and cost of wavelength management on the customer side. In simulation system, 1.25 Gb/s up/downstream data are transported with good performance. In addition the crosstalk penalties from adjacent wavelength channels （with the same OC） are found to be negligible in upstream and downstream transmissions.
基金the National Natural Science Foundation of China (No.60502004)
文摘In this paper,the sharing schemes of multicast in survivable Wavelength-Division Multi-plexed(WDM) networks are studied and the concept of Shared Risk Link Group(SRLG) is considered.While the network resources are shared by the backup paths,the sharing way is possible to make the backup paths selfish.This selfishness leads the redundant hops of the backup route and a large number of primary lightpaths to share one backup link.The sharing schemes,especially,the self-sharing and cross-sharing,are investigated to avoid the selfishness when computing the backup light-tree.In order to decrease the selfishness of the backup paths,it is important to make the sharing links fair to be used.There is a trade-off between the self-sharing and cross-sharing,which is adjusted through simulation to adapt the sharing degree of each sharing scheme and save the network resources.
文摘Recently, a tunable fiber Bragg grating(FBG) was developed by using stress-responsive colloidal crystals. In this paper, we have simulated the application of these nanoparticles into the super-structured fiber Bragg grating(SSFBG) written with perfect sequences derived from a short maximal-length sequence. A tunable SSFBG will be available to overcome the prohibitive temperature variation of the optical codecs. Nevertheless,we presented a method to implement coherent time spreading optical code-division multiple-access(OCDMA) where a unique code(or perfect sequence) can be reused and mixed with different wavelengths to obtain a tunable wavelength-division multiplexing(WDM)system. In order to maximize the binary throughput, we have selected a unique short maximal-length sequence composed of 7 chips that can be tuned with 7 different optical wavelengths. We found thousands of different tunable combinations that presented power contrast ratios(P/C) higher than 12 dB. When a WDM-OCDMA system used 2 different combinations simultaneously, the perfect binary detection with error correction codes was achieved successfully. The tunable SSFBG with colloidal crystals will be a simple and good alternative choice for fiber-to-the-home(FTTH) communications.
文摘Nyquist wavelength-division multiplexing （N-WDM） allows high spectral efficiency （SE） in long-haul transmission systems. Compared to polarization-division multiplexing quadrature phase-shift keying （PDM-QPSK）, multilevel modulation, such as PDM 16 quadrature-amplitude modulation （16-QAM）, is much more sensitive to intrachannel noise and interchannel linear crosstalk caused by N-WDM. We experimentally generate and transmit a 6 x 128 Gbit/s N-WDM PDM 16-QAM signal over 1200 km single-mode fiber （SMF）-28 with amplification provided by an erbium-doped fiber amplifier （EDFA） only. The net SE is 7.47 bit/s/Hz, which to the best of our knowledge is the highest SE for a signal with a bit rate beyond 100 Gbit/s using the PDM 16-QAM. Such SE was achieved by DSP pre-equalization of transmitter-side impairments and DSP post-equalization of channel and receiver-side impairments. Nyquist-band can be used in pre-equalization to enhance the tolerance of PDM 16-QAM to aggressive spectral shaping. The bit-error ratio （BER） for each of the 6 channels is smaller than the forward error correction （FEC） limit of 3.8 × 10-3 after 1200 km SMF-28 transmission.
基金Natural Science Foundation from Colleges and Universities of Jiangsu Provine(06KJD510034)
文摘Proposed is an interference type of optical analog-to-digital conversion(ADC). The refractive index of Fabry-Perot cavity changes with different voltages. The Fabry-Perot resonator converts electronic intensity into light wavelength through selecting lights of different wavelengthes. The parameters of the scheme are acquired with the transmission matrix of optical element and the time of steady-state light field. The maximum sampling speedes of 4-bit, 6-bit, 7-bit, 8-bit and 9-bit(ADC) are 1.695×1010 count/s, 4.33×109 count/s, 2.38×109 count/s, 1.24×109 count/s and 5.9×108 count/s, respectively.
基金supported in part by the National Key R&D Program of China under Grant No.2019YFB2205302。
文摘Low-cost,flexible and intelligent optical performance monitoring and management is a key enabling technology for network quality guarantee,especially in the era of explosive growth of communication capacity and network scale.However,to the best of our knowledge,it is extremely challenging to implement real-time performance monitoring and operations,administration and maintenance(OAM) in a highly complex dynamic network.In this paper,we propose an innovative optical identification(OID) scheme that can realize both performance monitoring and some advanced OAM sub-functions.The basic concepts,applications,challenges and evolution directions of this OID tool are also discussed.
文摘In order to realize broadband and high-speed transmission in the last mile access network,the Coded Wavelength-Division Multiplexing(Coded-WDM)technique on PON(so-called CDM-PON)is presented on fiber-to-the-home access network.In this paper,the codcd-WDM coder/decoder(codec}is configured on Optical Network Unit(ONU)and Optical Line Terminal(OLT)in Ethemet Passive Optical Network(E-PON).Here,network codecs are constructed with Arrayed Waveguide Grating(AWG)devices and the signature address code is employed as complementary Walsh code whose original code is for data bit'1'and complementary code is for data bit'0'respectively.It is shown that the simultaneous active user of proposed scheme using CWH code is improved 100%than using M-Sequence and conventional Walsh code for given bit error rate of 10^-9.In addition,the signal to noise ratio(SNR)performance is improved by 6dB compared with conventional scheme employed M-sequence and Walsh code.
基金supported by the National Natural Science Foundation of China(Grant Nos.U23B2047,62321166651,62205292,and 92150302)the Zhejiang Major Research and Development Program(Grant No.2021C01199)+1 种基金the Zhejiang Provincial Natural Science Foundation(Grant Nos.LZ18F050001,LD19F050001,LQ21F050006,and LD22F040004)the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(Grant No.2021R01001)。
文摘A high-performance silicon arrayed-waveguide grating(AWG)with 0.4-nm channel spacing for dense wavelength-division multiplexing systems is designed and realized successfully.The device design involves broadening the arrayed waveguides far beyond the single-mode regime,which minimizes random phase errors and propagation loss without requiring any additional fabrication steps.To further enhance performance,Euler bends have been incorporated into the arrayed waveguides to reduce the device’s physical footprint and suppress the excitation of higher modes.In addition,shallowly etched transition regions are introduced at the junctions between the free-propagation regions and the arrayed waveguides to minimize mode mismatch losses.As an example,a 32×32 AWG(de)multiplexer with a compact size of 900μm×2200μm is designed and demonstrated with a narrow channel spacing of 0.4 nm by utilizing 220-nm-thick silicon photonic waveguides.The measured excess loss for the central channel is∼0.65 dB,the channel nonuniformity is around 2.5 dB,while the adjacent-channel crosstalk of the central output port is−21.4 dB.To the best of our knowledge,this AWG(de)multiplexer is the best one among silicon-based implementations currently available,offering both dense channel spacing and a large number of channels.
基金the National Major Science and Technology Infrastructure Project of China“High Precision Ground-based Time Service System”(No.2017-000052-73-01-002401)the Youth Innovation Promotion Association,Chinese Academy of Sciences(No.2021407)the National Natural Science Foundation of China(No.12033007)。
文摘In this paper,we demonstrate the single-fiber and two-wavelength time transfer(SFTWTT)over a 2061 km field fiber loopback link network with a synchronous wavelength-division and time-division multiplexing access(WD-TDMA).This system utilizes wavelength-division multiplexing to avoid the impact of backscatter.In order to achieve high-precision time transfer,time-division multiplexing access is employed.This approach facilitates multiple bidirectional comparisons between local and remote devices.A digital phase-locked loop(PLL),which matches the bandwidth of the transfer system,and precision temperature control technology have been proposed to enhance the high stability of the fiber-optic time and frequency transfer system.The first on-site high-precision fiber-optic time transfer system exceeding 2000 km has been validated.Experimental results show that the stabilities of 5.6 ps@1 s and 3.1 ps@40,000 s can be achieved.The precision of time transfer over a 2061 km fiber-optic network,employing a single-fiber and two-wavelength approach,has been significantly enhanced.This study presents an average time difference of 52 ps across the distance,with a system uncertainty budgeted at 41.8 ps.This achievement signifies a substantial advancement in the realms of stability and reach for optical fiber time transfer,facilitating the development of a high-precision ground-based time service system.
文摘In this paper, an overview of author＇s research is presented, commencing at the University of Kent under Prof. David A. Jackson. Early research in short optical pulses and fiber-optic delay-line digital correlators led to optical communications research in code-division multiple access networking. This research was based on broadband incoherent light, and this theme continued with research into spectrum-sliced wavelength-division multiplexing. In shifting from photonics research to biomedical optics and biophotonics in the late 1990s, the emphasis on exploiting broadband light continued with research in optical coherence tomography, amongst other topics. In addition to the research outcomes, how these outcomes were attained is described, including mention of the exceptional contributions of many of my colleagues.
文摘This paper proposes a dynamic RWA scheme using fuzzy logic control on IP/GMPLS over WDM networks to achieve the best quality of network transmission. The proposed algorithm dynamically allocates network resources and reserves partial bandwidth based on the current network status, which includes the request bandwidth, average utilization for each wavelength and its coefficient of variance （C.V.） of data traffic, to determine whether the connection can be set tip. Five fuzzy sets for request bandwidth, average rate and C.V. of data traffic are used to divide the variable space： very large （LP）, large （SP）, normal （ZE）, small （SN）, and very small （LN）. Setting the fuzzy limit is a key part in the proposed algorithm. The simulation of scenarios in this paper has two steps. In the first step, the adaptive fuzzy limits are evaluated based on average transmission cost pertaining to ten network statuses. The second step is to compare the proposed algorithm with periodic measurement of traffic （PMT） in ATM networks in six network situations to show that the proposed FC-RWA algorithm can provide better network transmission.
