scholarly journals Joint Probabilistic-Nyquist Pulse Shaping for an LDPC-Coded 8-PAM Signal in DWDM Data Center Communications

2019 ◽  
Vol 9 (23) ◽  
pp. 4996 ◽  
Author(s):  
Han ◽  
Yang ◽  
Djordjevic ◽  
Yue ◽  
Wang ◽  
...  
Keyword(s):  
Wavelength Division Multiplexing ◽  
Spectral Efficiency ◽  
Data Center ◽  
Pulse Shaping ◽  
Direct Detection ◽  
Signal Transmission ◽  
Ldpc Code ◽  
Pulse Amplitude ◽  
Wavelength Division ◽  
Nyquist Pulse

M-ary pulse-amplitude modulation (PAM) meets the requirements of data center communication because of its simplicity, but coarse entropy granularity cannot meet the dynamic bandwidth demands, and there is a large capacity gap between uniform formats and the Shannon limit. The dense wavelength division multiplexing (DWDM) system is widely used to increase the channel capacity, but low spectral efficiency of the intensity modulation/direct detection (IM/DD) solution restricts the throughput of the modern DWDM data center networks. Probabilistic shaping distribution is a good candidate to offer us a fine entropy granularity and efficiently reduce the gap to the Shannon limit, and Nyquist pulse shaping is widely used to increase the spectral efficiency. We aim toward the joint usage of probabilistic shaping and Nyquist pulse shaping with low-density parity-check (LDPC) coding to improve the bit error rate (BER) performance of 8-PAM signal transmission. We optimized the code rate of the LDPC code and compared different Nyquist pulse shaping parameters using simulations and experiments. We achieved a 0.43 dB gain using Nyquist pulse shaping, and a 1.1 dB gain using probabilistic shaping, while the joint use of probabilistic shaping and Nyquist pulse shaping achieved a 1.27 dB gain, which offers an excellent improvement without upgrading the transceivers.

Combined Probabilistic Shaping and Nyquist Pulse Shaping for PAM8 Signal Transmission in WDM Systems

2019 ◽  
Author(s):  
Xiao Han ◽  
Mingwei Yang ◽  
Ivan B. Djordjevic ◽  
Yang Yue ◽  
Qiang Wang ◽  
...  
Keyword(s):  
Pulse Shaping ◽  
Signal Transmission ◽  
Nyquist Pulse

SEMICONDUCTOR WAVELENGTH TUNABLE OPTICAL FILTERS

1993 ◽  
Vol 02 (04) ◽  
pp. 643-659 ◽  
Author(s):  
T. NUMAI
Keyword(s):  
Wavelength Division Multiplexing ◽  
Direct Detection ◽  
Optical Filters ◽  
Switching Systems ◽  
Switching Speed ◽  
Photonic Switching ◽  
Detection Scheme ◽  
Wavelength Division ◽  
Wavelength Tunable ◽  
Tunable Optical Filters

Wavelength-division multiplexing (WDM) lightwave transmission systems and wavelength-division (WD) photonic switching systems are attractive for improvement in line capacity for lightwave telecommunication services, because they utilize a huge wavelength (frequency) domain as signal channels. Wavelength tunable optical filters are key devices for these WDM and WD systems in direct detection scheme. In particular, semiconductor wavelength tunable optical filters are suitable for monolithic integration with photonic devices such as semiconductor lasers, switches and detectors. Also, the switching speed of wavelength is faster than that of other optical filters. This paper briefly summarizes the state-of-the-art semiconductor wavelength tunable optical filters and their applications to WD photonic switching systems.

scholarly journals Integrated five-port non-blocking optical router based on mode-selective property

Nanophotonics ◽  
2018 ◽  
Vol 7 (5) ◽  
pp. 853-858 ◽  
Author(s):  
Hao Jia ◽  
Ting Zhou ◽  
Xin Fu ◽  
Jianfeng Ding ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Wavelength Division Multiplexing ◽  
Signal Transmission ◽  
Single Mode ◽  
Optical Signal ◽  
Selective Property ◽  
Optical Router ◽  
Wavelength Division ◽  
Spatial Modes ◽  
Measurement Results ◽  
Destination Port

AbstractIn this paper, we propose and demonstrate a five-port optical router based on mode-selective property. It utilizes different combinations of four spatial modes at input and output ports as labels to distinguish its 20 routing paths. It can direct signals from the source port to the destination port intelligently without power consumption and additional switching time to realize various path steering. The proposed architecture is constructed by asymmetric directional coupler based mode-multiplexers/de-multiplexers, multimode interference based waveguide crossings and single-mode interconnect waveguides. The broad optical bandwidths of these constituents make the device suitable to combine with wavelength division multiplexing signal transmission, which can effectively increase the data throughput. Measurement results show that the insertion loss of its 20 routing paths are lower than 8.5 dB and the optical signal-to-noise ratios are larger than 16.3 dB at 1525–1565 nm. To characterize its routing functionality, a 40-Gbps data transmission with bit-error-rate (BER) measurement is implemented. The power penalties for the error-free switching (BER<10−9) are 1.0 dB and 0.8 dB at 1545 nm and 1565 nm, respectively.

scholarly journals Spectral Efficient Asymmetrically Clipped Hybrid FBMC for Visible Light Communication

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Sanjeev Kumar ◽  
Preeti Singh
Keyword(s):  
Visible Light ◽  
Amplitude Modulation ◽  
Spectral Efficiency ◽  
Filter Bank ◽  
Direct Detection ◽  
Average Power ◽  
Pulse Amplitude ◽  
Visible Light Communication ◽  
Discrete Multitone ◽  
Filter Bank Multicarrier

Filter bank multicarrier (FBMC) modulation has shown sufficient potential for wireless communication. A hybrid optical FBMC technique is proposed to improve the spectral efficiency of a visible light communication (VLC) system. In this technique, a hybrid asymmetrically clipped optical offset quadrature amplitude modulation FBMC (HACO-OQAM-FBMC) modulation technique is used. Asymmetrically clipped optical FBMC (ACO-FBMC) is used for odd subcarriers, and pulse amplitude modulation-discrete multitone (PAM-DMT) is used for the even subcarriers. The proposed hybrid scheme uses an intensity modulation/direct detection (IM/DD) channel. It is shown that there is no interference on odd subcarriers using the proposed method and receiver demodulation is similar to that of ACO-FBMC receiver. However, clipping noise of ACO-FBMC falls on PAM-DMT subcarriers, which can be cancelled at receiver processing after estimation. The analytical performance of the proposed technique is compared using parameters, namely, bit error rate (BER), spectral efficiency, computational complexity, and peak to average power ratio (PAPR). It is found that HACO-OQAM-FBMC is more spectral efficient than ACO-FBMC and other OFDM-based techniques.

scholarly journals 100 Gb/s wavelength division multiplexing four‐level pulse amplitude modulated transmission over 160 km using advanced optical fibres

2018 ◽  
Vol 54 (11) ◽  
pp. 699-701 ◽  
Author(s):  
J.D. Downie ◽  
J. Hurley ◽  
R. Nagarajan ◽  
T. Maj ◽  
H. Dong ◽  
...  
Keyword(s):  
Wavelength Division Multiplexing ◽  
Pulse Amplitude ◽  
Optical Fibres ◽  
Wavelength Division
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