Arrayed waveguide grating (AWG) device,a novel compact structure,is presented based on silicon on insulator (SOI) material.A total internal reflection (TIR) waveguide mirror is fabricated at the middle of each arr...Arrayed waveguide grating (AWG) device,a novel compact structure,is presented based on silicon on insulator (SOI) material.A total internal reflection (TIR) waveguide mirror is fabricated at the middle of each arrayed waveguide.An approach of compensating TE TM mode polarization is presented by using the phase difference,which is caused by TIR at the waveguide mirror.This AWG device has advantage for its small size and simple technigue of fabrication.The experimental results are given and the feasibility of fabrication is tested.展开更多
A new method of constructing regular low-density parity-check (LDPC) codes was proposed. And the novel class of LDPC codes was applied in a coded orthogonal frequency division multiplexing (OFDM) system. This method e...A new method of constructing regular low-density parity-check (LDPC) codes was proposed. And the novel class of LDPC codes was applied in a coded orthogonal frequency division multiplexing (OFDM) system. This method extended the class of LDPC codes which could be constructed from shifted identity matrices. The method could avoid short cycles in Tanner graphs with simple inequation in the construction of shifting identity matrices, which made the girth of Tanner graphs 8. Because of the quasicyclic structure and the inherent block configuration of parity-check matrices, the encoders and the decoders were practically feasible. They were linear-time encodable and decodable. The LDPC codes proposed had various code rates, ranging from low to high. They performed excellently with iterative decoding and demonstrate better performance than other regular LDPC codes in OFDM systems.展开更多
The disequilibrium of the optical power among different channels is analyzed for the dense wavelength division multiplexing optical communication systems. And the new technologies and devices for optical amplifying, f...The disequilibrium of the optical power among different channels is analyzed for the dense wavelength division multiplexing optical communication systems. And the new technologies and devices for optical amplifying, filtering, adding /dropping,etc,have been reviewed, which can be used to equalize dynamically the optical power in optical networks.展开更多
A novel adaptive ordered LDPC （low-density parity-check） coded OFDM （orthogonal frequency-division multiplexing） transmission technique is proposed to exploit different error probabilities of irregular LDPC coded ...A novel adaptive ordered LDPC （low-density parity-check） coded OFDM （orthogonal frequency-division multiplexing） transmission technique is proposed to exploit different error probabilities of irregular LDPC coded bits in OFDM systems. Assuming that the CSI （channel state information） is known at the transmitter, the irregular LDPC coded bits are ordered according to their degrees and then allocated into subcarriers adaptively. Bits with higher degrees are allocated into less attenuated subcarriers and bits with lower degrees are allocated into deep attenuated subcarriers. Quantization on CSI feedback can be applied to minimize the signaling overhead. Performance of this strategy is analyzed by density evolution and numerical simulation. Simulation results show that about a 1 to 1.5 dB gain in terms of SNR （ signal to noise ratio） can be achieved over frequency-selective fading channels compared to conventional LDPC coded OFDM systems without ordering, and the proposed scheme is robust to CSI quantization.展开更多
Multiwavelength chirped fiber Bragg grating (MCFBG) is a more valuable approach to chromatic dispersion compensation. And adjusting the structure of FBG will optimize the performance of dispersion compensator in 8...Multiwavelength chirped fiber Bragg grating (MCFBG) is a more valuable approach to chromatic dispersion compensation. And adjusting the structure of FBG will optimize the performance of dispersion compensator in 8×10 Gb/s DWDM network, which is proved by simulating calculation.展开更多
A novel filter structure which can reduce the crosstalk in cross-connection and switching in all optical networks based on dense wavelength division multiplexing (DWDM) is presented. The filter is constructed by diele...A novel filter structure which can reduce the crosstalk in cross-connection and switching in all optical networks based on dense wavelength division multiplexing (DWDM) is presented. The filter is constructed by dielectric waveguide with the waveguide boundary or the waveguide itself uncontinuous in transmitting direction. Using the concept of effective refractive index of plane waveguide system, we can get a special index profile along the wave propagation direction by alternatively changing the thickness of waveguide film or its refractive index. Having proved this kind of waveguides with filtering properties, the design principle of an example is given, which will be very useful to reduce the crosstalk in optical cross-connection and switching in all optical networks based on DWDM. This kind of filters can be easily connected with other related component.展开更多
Based on the electromagnetic field theory, the optical signal transmission characteristics in input/output waveguides, slab waveguides and arrayed waveguides of the arrayed waveguide grating (AWG) multi/demultiplexer ...Based on the electromagnetic field theory, the optical signal transmission characteristics in input/output waveguides, slab waveguides and arrayed waveguides of the arrayed waveguide grating (AWG) multi/demultiplexer are analyzed. The relationship between the physical parameters such as geometry sizes and relative refractive index in AWG multi/demultiplexer and the optical signal transmission characteristics are discussed. This theoretical study can be used for optimizing the design and improving the performance of the AWG multi/demultiplexer.展开更多
The rectangular optical filter is one of the most important optical switching components in the dense wavelength divi- sion multiplexing （DWDM） fiber-optic communication system and the intelligent optical network. T...The rectangular optical filter is one of the most important optical switching components in the dense wavelength divi- sion multiplexing （DWDM） fiber-optic communication system and the intelligent optical network. The integrated high- order silicon microring resonator （MRR） is one of the best candidates to achieve rectangular filtering spectrum re- sponse. In general, the spectrum response rectangular degree of the single MRR is very low, so it cannot be used in the DWDM system. Using the high-order MRRs, the bandwidth of flat-top pass band, the out-of-band rejection degree and the roll-off coefficient of the edge will be improved obviously. In this paper, a rectangular optical filter based on high- order MRRs with uniform couplers is presented and demonstrated. Using 15 coupled race-track MRRs with 10 pm in radius, the 3 dB flat-top pass band of 2 nm, the out-of-band rejection ratio of 30 dB and the rising and falling edges of 48 dB/nm can be realized successfully.展开更多
In this paper,a new type of multi-wavelength fiber laser is proposed and demonstrated experimentally.Superimposed fiber grating(SIFG) and chirp fiber Bragg grating(CFBG) are used for wavelength selection.Based on gain...In this paper,a new type of multi-wavelength fiber laser is proposed and demonstrated experimentally.Superimposed fiber grating(SIFG) and chirp fiber Bragg grating(CFBG) are used for wavelength selection.Based on gain equalization technology,by finely adjusting the stress device in the cavity,the gain and loss are equal,so as to suppress the modal competition and achieve multi-wavelength lasing at room temperature.The experimental results show that the laser can output stable multi-wavelength lasers simultaneously.The laser coupling loss is small,the structure is simple,and it is convenient for integration,so it can be widely used in dense wavelength division multiplexing(DWDM) system and optical fiber sensors.展开更多
A cost-effective ultra-dense wavelength-division-multiplexed passive optical network(UD-WDM PON) with speed of 12.5 Gbit/s and channel spacing of 12.5 GHz is proposed and demonstrated. The distributed feedback(DFB) la...A cost-effective ultra-dense wavelength-division-multiplexed passive optical network(UD-WDM PON) with speed of 12.5 Gbit/s and channel spacing of 12.5 GHz is proposed and demonstrated. The distributed feedback(DFB) lasers modulated in 4-level pulse amplitude modulation(4-PAM) format are used for downstream links, and the reflective semiconductor optical amplifiers(RSOAs) together with an optical frequency comb modulated in quadrature phase shift keying(QPSK) format are used for upstream links. We can achieve the error-free transmission of the upstream signals with speed of 12.5 Gbit/s even after 20 km single-mode fiber(SMF). The power penalty obtained by using the frequency comb generator instead of a tunable laser is around 0.5 d B. By using 11 DFB lasers and a set of intensity and phase modulators, it is possible to provide the seed light for 297 optical network units(ONUs) within the C-band.展开更多
文摘Arrayed waveguide grating (AWG) device,a novel compact structure,is presented based on silicon on insulator (SOI) material.A total internal reflection (TIR) waveguide mirror is fabricated at the middle of each arrayed waveguide.An approach of compensating TE TM mode polarization is presented by using the phase difference,which is caused by TIR at the waveguide mirror.This AWG device has advantage for its small size and simple technigue of fabrication.The experimental results are given and the feasibility of fabrication is tested.
文摘A new method of constructing regular low-density parity-check (LDPC) codes was proposed. And the novel class of LDPC codes was applied in a coded orthogonal frequency division multiplexing (OFDM) system. This method extended the class of LDPC codes which could be constructed from shifted identity matrices. The method could avoid short cycles in Tanner graphs with simple inequation in the construction of shifting identity matrices, which made the girth of Tanner graphs 8. Because of the quasicyclic structure and the inherent block configuration of parity-check matrices, the encoders and the decoders were practically feasible. They were linear-time encodable and decodable. The LDPC codes proposed had various code rates, ranging from low to high. They performed excellently with iterative decoding and demonstrate better performance than other regular LDPC codes in OFDM systems.
文摘The disequilibrium of the optical power among different channels is analyzed for the dense wavelength division multiplexing optical communication systems. And the new technologies and devices for optical amplifying, filtering, adding /dropping,etc,have been reviewed, which can be used to equalize dynamically the optical power in optical networks.
基金The National High Technology Research and Devel-opment Program of China (863Program) (No2002AA123031)
文摘A novel adaptive ordered LDPC （low-density parity-check） coded OFDM （orthogonal frequency-division multiplexing） transmission technique is proposed to exploit different error probabilities of irregular LDPC coded bits in OFDM systems. Assuming that the CSI （channel state information） is known at the transmitter, the irregular LDPC coded bits are ordered according to their degrees and then allocated into subcarriers adaptively. Bits with higher degrees are allocated into less attenuated subcarriers and bits with lower degrees are allocated into deep attenuated subcarriers. Quantization on CSI feedback can be applied to minimize the signaling overhead. Performance of this strategy is analyzed by density evolution and numerical simulation. Simulation results show that about a 1 to 1.5 dB gain in terms of SNR （ signal to noise ratio） can be achieved over frequency-selective fading channels compared to conventional LDPC coded OFDM systems without ordering, and the proposed scheme is robust to CSI quantization.
文摘Multiwavelength chirped fiber Bragg grating (MCFBG) is a more valuable approach to chromatic dispersion compensation. And adjusting the structure of FBG will optimize the performance of dispersion compensator in 8×10 Gb/s DWDM network, which is proved by simulating calculation.
文摘A novel filter structure which can reduce the crosstalk in cross-connection and switching in all optical networks based on dense wavelength division multiplexing (DWDM) is presented. The filter is constructed by dielectric waveguide with the waveguide boundary or the waveguide itself uncontinuous in transmitting direction. Using the concept of effective refractive index of plane waveguide system, we can get a special index profile along the wave propagation direction by alternatively changing the thickness of waveguide film or its refractive index. Having proved this kind of waveguides with filtering properties, the design principle of an example is given, which will be very useful to reduce the crosstalk in optical cross-connection and switching in all optical networks based on DWDM. This kind of filters can be easily connected with other related component.
文摘Based on the electromagnetic field theory, the optical signal transmission characteristics in input/output waveguides, slab waveguides and arrayed waveguides of the arrayed waveguide grating (AWG) multi/demultiplexer are analyzed. The relationship between the physical parameters such as geometry sizes and relative refractive index in AWG multi/demultiplexer and the optical signal transmission characteristics are discussed. This theoretical study can be used for optimizing the design and improving the performance of the AWG multi/demultiplexer.
基金supported by the National Natural Science Foundation of China(No.61205062)the Scientific Research Project of Hubei Education Department(No.B2015191)the Project of Hubei Province Universities Outstanding Youth Scientific Innovation Team(Nos.T201431 and T201633)
文摘The rectangular optical filter is one of the most important optical switching components in the dense wavelength divi- sion multiplexing （DWDM） fiber-optic communication system and the intelligent optical network. The integrated high- order silicon microring resonator （MRR） is one of the best candidates to achieve rectangular filtering spectrum re- sponse. In general, the spectrum response rectangular degree of the single MRR is very low, so it cannot be used in the DWDM system. Using the high-order MRRs, the bandwidth of flat-top pass band, the out-of-band rejection degree and the roll-off coefficient of the edge will be improved obviously. In this paper, a rectangular optical filter based on high- order MRRs with uniform couplers is presented and demonstrated. Using 15 coupled race-track MRRs with 10 pm in radius, the 3 dB flat-top pass band of 2 nm, the out-of-band rejection ratio of 30 dB and the rising and falling edges of 48 dB/nm can be realized successfully.
基金supported by the National Natural Science Foundation of China(Nos.61205068 and 61475133)the Natural Science Foundation of Hebei Province(No.F2015203270)+1 种基金the Science and Technology Program of Hebei Province(Nos.4273301D,13210409 and 15273304D)the College Youth Talent Project of Hebei Province(No.BJ2014057)
文摘In this paper,a new type of multi-wavelength fiber laser is proposed and demonstrated experimentally.Superimposed fiber grating(SIFG) and chirp fiber Bragg grating(CFBG) are used for wavelength selection.Based on gain equalization technology,by finely adjusting the stress device in the cavity,the gain and loss are equal,so as to suppress the modal competition and achieve multi-wavelength lasing at room temperature.The experimental results show that the laser can output stable multi-wavelength lasers simultaneously.The laser coupling loss is small,the structure is simple,and it is convenient for integration,so it can be widely used in dense wavelength division multiplexing(DWDM) system and optical fiber sensors.
基金supported by the National Natural Science Foundation of China(No.61475015)
文摘A cost-effective ultra-dense wavelength-division-multiplexed passive optical network(UD-WDM PON) with speed of 12.5 Gbit/s and channel spacing of 12.5 GHz is proposed and demonstrated. The distributed feedback(DFB) lasers modulated in 4-level pulse amplitude modulation(4-PAM) format are used for downstream links, and the reflective semiconductor optical amplifiers(RSOAs) together with an optical frequency comb modulated in quadrature phase shift keying(QPSK) format are used for upstream links. We can achieve the error-free transmission of the upstream signals with speed of 12.5 Gbit/s even after 20 km single-mode fiber(SMF). The power penalty obtained by using the frequency comb generator instead of a tunable laser is around 0.5 d B. By using 11 DFB lasers and a set of intensity and phase modulators, it is possible to provide the seed light for 297 optical network units(ONUs) within the C-band.
