Recent Progress in High-speed and High Spectral Efficiency Optical Transmission Technology

Increasing the spectral efficiency and per channel data rate have historically been shown to be the most cost-effective method to meet the need of ever growing capacity demand in the core network. In this paper we review recent progress in high-speed and high-spectral-efficient optical transmission technology. We discuss spectrally efficient modulation and detection technologies that have been experimentally explored for future 100-Gb/s and above optical transmission system. Emerging methods aiming at extending system reach for noise and nonlinearity-stressed high spectral efficiency optical transmission systems have also been reviewed. We show that spectrallyefficient multilevel coding coupled with polarization multiplexing and digital coherent detection has the potential to enable 400Gb/s per channel WDM system operating with existing 50GHzspaced WDM infrastructure at a spectral efficiency of 8b/s/Hz.

Theoretical and Experimental Investigation on a 40Gb/s FSK transmission Link

A novel Frequency Shift Keying (FSK) transmitter that can operate at 40Gb/s and above is proposed. The transmission characteristics of a FSK signal at 40Gb/s are investigated under varying dispersion management. The resilience of compensation ratio and power level is obtained. We also experimentally demonstrate transmission over 100km SMF and transparent wavelength conversion based on a semiconductor optical amplifier.

High Spectral Efficiency 400G Transmission

This paper gives an overview of the generation and transmission of 450 Gb/s wavelengthdivision multiplexed （WDM） channels over the standard 50 GHz ITU grid at a net spectral efficiency （SE） of 8.4 b/s/Hz. The use of nearly ideal Nyquist pulse shaping, spectrallyefficient highorder modulation format, distributed Raman amplification, distributed compensation of RADM filtering effects, coherent equalization, and highcoding gain forward error correction （FEC） code may enable future 400G systems to operate over the standard 50 GFIz grid optical network.

Investigation of Differently Modulated Optical Signals Transmission in HDWDM Systems

The authors＇ developed combined system model can be considered under the concept of next generation optical network （NGON） as a model for the future design of backbone networks. Such solution can be topical in the result of different telecom operators＇ optical networks convergence. In this case a necessity to transmit differently modulated signals over a single optical fiber even with different bit rates may occur. This research is performed with OptSim 5.2 simulation software that numerically solves nonlinear SchrOdinger equation. The authors have revealed the optimal parameter configuration for developed combined transmission systems and obtained in system＇s channels detected signals bit-error-rate （BER） correlation diagrams. They represent BER as a function from different system＇s parameters such as channel output power level, optical amplifier fixed output power level and system＇s channels allotment in C-band of ITU-T （Telecommunication Standardization Sector of the International Telecommunications Union） recommended spectral grid. As well as these obtained BER values were compared with the results for similar system, where instead of standard single mode fiber （according ITU-T Rec. G.652 D） optical signals are transmitted over non-zero dispersion shifted fiber （ITU-T Rec. G. 655）.

Adaptive and Intelligent Digital Signal Processing for Improved Optical Interconnection

In recent years, explosively increasing data traffic has been boosting the con?tinuous demand of high speed optical interconnection inside or among data centers, high performance computers and even consumer electronics. To pursue the improved intercon?nection performance of capacity, energy efficiency and simplicity, effective approaches are demonstrated including particularly advanced digital signal processing (DSP) meth?ods. In this paper, we present a review about the enabling adaptive DSP methods for opti?cal interconnection applications, and a detailed summary of our recent and ongoing works in this field. In brief, our works focus on dealing with the specific issues for short-reach interconnection scenarios with adaptive operation, including signal-to-noise-ratio (SNR) limitation, level nonlinearity distortion, energy efficiency consideration and the de?cision precision.

Advanced modulation formats for underwater visible light communications [Invited]

In this paper, we present a detailed comparison of applying three advanced modulation formats including carrierless amplitude and phase modulation(CAP), orthogonal frequency division multiplexing(OFDM), and discrete Fourier transform spread orthogonal frequency division multiplexing(DFT-S OFDM) in underwater visible light communication(UVLC) systems. Cascaded post-equalization schemes are suggested to compensate the system impairments. For the first time, a two-level post-equalizer is presented to mitigate the nonlinear effect and improve the system performance of UVLC. The first post-equalization is based on a novel recursive least square Volterra. These modulation formats are all experimentally demonstrated with corresponding digital signal processing(DSP) algorithms. The experimental results show that single carrier modulations including CAP and DFT-S OFDM can outperform OFDM. Our experiment results show that up to 3 Gb/s over a 1.2 m underwater visible light transmission can be achieved by using DFT-S OFDM 64 QAM and CAP-64. The measured bit error rate is well under the hard decision-forward error correction(HD-FEC) threshold of 3.8 × 10^(-3).

Experimental demonstration and analysis of all-optical label swapping based on RZ-DQPSK/IRZ-ASK modulation format

A novel optical return zero differential quadrature phase shifted keying/inverse return zero amplitude shifted keying （RZ-DQPSFUIRZ-ASK） orthogonal modulation format scheme for all-optical label swapping is analyzed theoretically and experimentally. The transmission characteristics of RZ-DQPSK/IRZ-ASK modulation format transmission system are demonstrated. Results show that high extinction ratio is obtained for IRZ-ASK label signal while at the same time the all-optical label swapping, differential quadrature phase shifted keying （DQPSK） payload signal is hardly affected. It requires only 0.9 dB higher power penalty compared to 21.4 Gbit/s RZ-DQPSK modulation format and less than 2 dB transmission penalty after 60 km. The proposed scheme is a practical solution for meeting the data rate and cost-efficiency of the optical links simultaneously in future all-optical label swapping.

Power distribution analysis for multiple modulation formats in an all-optical sampling wavelength division multiplexing system

An optimal power distribution analysis for an all-optical sampling orthagonal frequency division multiplexing(OFDM) scheme with multiple modulation formats including diferential phase shift keyed(DPSK), diferential quadrature phase shift keyed(DQPSK), and non-return-to-zero(NRZ) is proposed. The noise tolerances of different modulation formats are analyzed, and the optimal input power ratio between phase and intensity modulation formats for the best overall receiving performance is investigated under unchanged total input power. Moreover, this scheme can seamlessly coexist with the traditional WDM channel.

An optical modulation format generation scheme based on spectral filtering and frequency-to-time mapping

An optical modulation format generation scheme based on spectral filtering and frequency-to-time mapping is experimentally demonstrated. Many modulation formats with continuously adjustable duty radio and bit rate can be formed by changing the dispersion of dispersion element and the bandwidth of shaped spectrum in this scheme. In the experiment, non-return-to-zero(NRZ) signal with bit rate of 29.41 Gbit/s and 1/2 duty ratio return-to-zero(RZ) signal with bit rate of 13.51 Gbit/s are obtained. The maximum bit rate of modulation format signal is also analyzed.

Optimal modulation formats for 2560 km optical transmission with low power penalty

The production mechanism of non-return-to-zero(NRZ),return-to-zero(RZ)and carrier suppressed return-to-zero(CSRZ)was analyzed theoretically in this paper.We compared the transmission performance of CSRZ with RZ and NRZ formats at 10 Gb/s system by numerical simulation.And we simulated the transmission model constructed with Erbium-doped fiber amplifier(EDFA)as the solo amplifier and the chirped fiber Bragg grating(CFBG)as the solo dispersion compensator used in the system.A practical 8x10 Gb/s 2560 km transmitted experiment was conducted in straight line with these different modulation formats mentioned above and the experiment results show very good agreement with the result of computer simulation.The CSRZ format is more effective than other formats in the system,and involved only 2.5 dB power penalty cost in the practical 2560 km error-free experiment.The results also show that CSRZ will help to optimize the transmitted results and reduce the transmitted penalty further.

NEW STRATEGIES FOR THE CONTROL OF BACTERIAL INFECTIONS: MODULATORS OF QUORUM SENSING AND BIOFILM FORMATION FROM MALAGASY DALBERGIA SPECIES

Considering the WHO warning about the emergence of a’post-antibiotic’era during the 21st century in which common infections and minor injuries will have a dramatic impact on human death toll,search for new potential antibacterial drug targets became a necessary need.Targets that are extensively explored concern the modulation

A simple experimental scheme for M-QAM optical signals generation

A simple scheme to generate optical quad- rature amplitude modulation （QAM） signals is proposed based on different types of delay interferometers （Dis）. The simulated results show that 16QAM, 64QAM and 256 QAM optical signals can be generated by 2×2, 3 ×3 and 4×4 DI, respectively, and the outputs of the proposed scheme are similar to those of the conventional schemes. The operation principle is discussed and the transmission properties of the square 16QAM as well as 64QAM signals are analyzed and compared with common approach.