DPSK Transmission Research Articles

Efficient employment of optical DPSK transmitter with linear multimode fibers and FSO channel under various duty cycle coding effects

Abstract This study has demonstrated the efficient employment of optical DPSK transmitter with linear multimode fibers and FSO channel under various duty cycle coding effects. The light signal power form variations after linear multimode fiber versus spectral wavelength based various RZ-percentage duty cycle coding is clarified. The light signal power form variations after linear multimode fiber versus spectral wavelength based various NRZ duty cycle coding is also clarified. The light power signal form variations after FSO channel versus spectral wavelength based different RZ percentage duty cycle coding is analyzed. Moreover the light power signal form variations after FSO channel versus spectral wavelength based NRZ percentage duty cycle coding is investigated. The light signal power form variations after linear multimode fiber versus spectral wavelength based various RZ percentage duty cycle coding and NRZ modulation code are indicated.

Energy Efficient Design of Optical DPSK Transmitter Using High Performance and High Range IO Standard

Energy Efficient Design of Optical DPSK Transmitter Using High Performance and High Range IO Standard

High Performance and High Range Design of 100Gb/s Optical Differential Phase Shift keying Transmitter

The need of high performance and high range devices is increasing drastically as rapid growth is accumulating in Information and communication technology (ICT). In Gb/s transmission system high speed optical transmitter requires high power for transmitting information at long distance. The high power transmitters consumes enormous power and exhibits heating effect in devices, leakage power problems as well due to that the device response became slower. In this work, high performance and high range design of 100Gb/s optical DPSK transmitter is designed in 20 nm Field Programming Gate Array (FPGA) using multiple IO standards. The high performance and high range design is achieved using proposed technique by integrating the two IO Standards one is Pseudo Open Drain (POD) and other is PointtoPoint Differential Signaling (PPDS). The POD IO standards is consuming less power feature, while PPDS IO Standard provides the faster response time. It is determined that using proposed technique the 95% power consumption is recorded with 85% improved efficiency in response time for mid-range infrared frequencies such as 200 GHz, 500 GHz, 90 GHz, 5 THz and 20 THz. The designed energy efficient optical transmitter can be assimilate with further optical components in optical communication systems to high performance and high range future generation networks.

Energy Efficient Design of 100Gb/s Optical DPSK Transmitter Design using UltraScale FPGA

Information and Communication Technology (ICT) is growing rapidly, and ICT devices are consuming plenty of energy, for communication systems. In Gb/s transmission system high range and high- speed optical transmitter requires high power for transmitting information at long distance. The existing techniques are consuming vast amount of power, exhibits heating effect, and leakage power problems for optical transmitter of 40 Gb/s or more. In this work, an energy efficient 100Gb/s optical DPSK transmitter is designed using UltraScale Field Programming Gate Array (FPGA). The design is realized by controlling the impedance of 100Gb/s optical DPSK transmitter using Digitally Controlled Impedance (DCI) IO (Input/ Output) Standards available on UltraScale FPGA. It is determined that 80% power is reduced using designed 100Gb/s optical DPSK transmitter, for 100 GHz, 300 GHz, 900 GHz and 12 THz using High Speed Low Voltage DCI (HSLVDCI_15) IO Standard compared to optical transmitter design without IO Standard. Furthermore, using designed system 90% leakage power is also reduced. The designed energy efficient optical transmitter can be interfaced with other optical components, to provide the green optical communication.

All Regeneration for Optical Communication Network Using Optical 3R Regeneration and Phase Sensitive Amplifier

Nonlinear optical effects in fibers occur via ultrafast Kerr nonlinearity, offers a flexible framework within which numerous signal-processing functions can be accomplished. When high power launched in optical fiber, several nonlinear transmission impairment such as amplitude noise, phase noise, power spectral losses, that degrades the performance of optical communication system. All optical regeneration is one of the solution to mitigate transmission impairments instead of optical to electrical conversion. In this paper, all optical regeneration is demonstrated for 10Gb/s DPSK system using 3R regeneration and Phase sensitive amplification to mitigate amplitude and nonlinear phase noise form 10G noisy DPSK transmission system. Bit error rate of 10-11 is achieved at power penalty of 6 dB. The system is developed and tested using optisystem. The developed all optical regeneration system is very demanding for long distance transmission in high-speed communication systems.

Unrepeatered DPSK transmission over 360 km SMF-28 fibre using URFL based amplification.

Unrepeatered 42.7 Gb/s per channel RZ-DPSK transmission over standard SMF-28 fibre with novel URFL based amplification using fibre Bragg gratings is investigated. OSNR and gain performance are studied experimentally and through simulations. Error free transmission for 16 channels across the full C-band with direct detection was experimentally demonstrated for 280 km span length, as well as 6-channel transmission at 340 km and single-channel transmission up to 360 km (75 dB) without employing ROPA or specialty fibres.

Performance Enhancement of Atmospheric Coherent Optical Communication Systems Using DPSK

A coherent DPSK transmission system is presented to improve the receiver sensitivity for free space optical (FSO) communication. The coherent DPSK is an effective way to overcome the atmospheric turbulence. The eye diagram and bit error rate (BER) of the system are got by the simulation. Results show that with the coherent reception method, coherent DPSK offers improved signal-to-noise ratio (SNR) performance compared to the DPSK without coherent and OOK format. And hence it can be effective to overcome the signal impairment caused by atmospheric turbulence. It is shown that the sensitivity of the system employing coherent DPSK is 3dB better than a comparable system using DPSK without coherent and 9dB better than a system using OOK.

Design and Realization of 10Gbps DPSK System for Free Space Optical Communication

The performance of atmospheric communication system is limited by the atmospheric turbulence. In this paper, we present a practical 10Gbps DPSK transmission system for free space optical (FSO) communication with low error probability and wide-opening eye diagram. Compared to OOK modulation, DPSK format is a more effective way to resist the atmospheric turbulence. In addition, we designed parameters of this modulation system to be varied as the channel situation changed to achieve an optimized performance. The experiment results show that such a DPSK system could greatly overcome the atmospheric turbulence.

Amplitude regeneration of NRZ–DPSK signal with a feed-forward control circuit

An optical-and-electrical hybrid-type amplitude regenerator for an NRZ–DPSK signal suffering from optical amplifier noise is described. The system is a feed-forward control circuit composed of a coupler, a photo detector, and an intensity modulator, and works to suppress intensity fluctuations in a DPSK signal while preserving phase information. A schematic explanation of how the DPSK transmission performance is improved with intensity noise suppression during transmission is presented, and an experiment to demonstrate its effect is conducted.

Phase noise suppression in a DPSK transmission system by the use of an attenuation-imbalanced NOLM

A nonlinear optical loop mirror (NOLM) imbalanced by attenuation has been used for the suppression of nonlinear phase noise in a DPSK transmission system. It has been experimentally shown that such a passive, NOLM-based regenerator can significantly improve the performance of a phase-encoded transmission when it is limited by nonlinear phase noise. A brief overview over the advantages und limitations of different NOLM-based phase-preserving amplitude regenerators is also given.

FWM Compensation in DPSK Transmission by Reducing Detectors withDigital Coherent Detection Using Backward Propagation

FWM Compensation in DPSK Transmission by Reducing Detectors withDigital Coherent Detection Using Backward Propagation

Compensation for FWM in DPSK Transmission by Reducing Detectors with Coherent Detection through Digital Signal Processing

Compensation for FWM in DPSK Transmission by Reducing Detectors with Coherent Detection through Digital Signal Processing

Characterization of a tunable three-section slotted Fabry–Perot laser for advanced modulation format optical transmission

In this paper we report on the characterization of a narrow linewidth three-section tunable slotted Fabry–Perot laser. The SMSR of the 25 available 100-GHz ITU channels is above 30 dB, whereas their average linewidth is 538 kHz with a maximum below 800 kHz. The RIN spectra of six different channels are also measured and a maximum average RIN of −135 dB/Hz is obtained. The linewidth effect of the laser in a 1.25 Gb/s DPSK transmission system is investigated by comparing the performance between the slotted Fabry–Perot laser and a commercial SG-DBR laser respectively. Error free transmission of the slotted Fabry-Perot laser shows the benefit of the narrow linewidth of the device for systems employing advanced modulation formats.

Linewidth of SG-DBR laser and its effect on DPSK transmission

In this paper the linewidth of widely tunable SG-DBR lasers has been investigated theoretically and experimentally. We demonstrate experimentally the importance of obtaining low linewidth operation for the application of SG-DBR laser with advanced modulation format transmission. This is achieved by choosing two sets of tuning currents for an SG-DBR laser that give the same wavelength channel and good SMSR, but different linewidths. When the laser is employed in a DPSK system only the operating point (the set of drive currents used to obtain specific output characteristics) that portrays low linewidth achieves error free transmission. This work shows that although calibration of tunable lasers is normally based on achieving sufficient SMSR and output power, it will be important to consider the linewidth parameter as these lasers begin to be used in more spectrally efficient WDM systems employing advanced modulation formats. The simulation results illustrate that the operating points which achieve narrow linewidth are correlated with those that exhibit low threshold current. This finding may be used for calibration of SG-DBR lasers to achieve minimum linewidth at each operating wavelength.

Simulative analysis of soliton-based DPSK transmission system

The effectiveness of the conventional dispersion compensation techniques: DCF, FBG and OPC to use with soliton transmission is presented. The frequency shifts of solitons induced by collisions between different channels in a soliton WDM system can be reduced by dispersion compensation. The reduction mechanism applied is the cancellation of the shifts generated in both normal and anomalous dispersion regimes. It is analyzed that phase jitter can be reduced by the use of midway spectral inversion.

DWDM 43 Gbit/s DPSK transmission over 1200 km with no inline dispersion compensation

Error-free dense wavelength division multiplexed (DWDM) transmission of 43 Gbit/s DPSK signals transmitted and detected by a commercial transponder is demonstrated over 1200 km of NZ-DSF with 50 GHz channel spacing and no inline dispersion compensation. Custom slope-matched dispersion compensation modules provide terminal-only compensation, facilitating a simple system configuration with performance >3 dB above the forward error correction threshold.

Evaluation of nonlinear phase noise in DPSK transmission for different link designs

We analyzed the impact of nonlinear phase noise caused by Gorden-Mollenauer effect in single-channel return-tozero differential phase-shift-keying (RZ-DPSK) transmission in dependence of system bit rates, dispersion compensation schemes and different fiber types. The investigation is reported by simulating RZ-DPSK signals for 3200 km, taking into account penalties in Q-factor induced by nonlinear phase noise. From these simulation results, higher bitrate systems, system with pre-compensation schemes and system using stand single mode fiber transmission are more robust against nonlinear phase noise. Furthermore, by looking into the standard deviation of the signal intensity and phase for all sampling points within one-bit duration, we observed that optical noise can be washed out from the bit center during propagation.

Nonlinear Phase Noise Reduction in a DPSK Transmission System Using Cascaded Nonlinear Amplifying Loop Mirrors

The performance of a nonlinear amplifying loop mirror as a phase-preserving amplitude 2R regenerator in a differential phase-shift-keying transmission system with nonlinear phase noise as dominant limiting effect has been investigated in a recirculating fiber-loop setup. The experimental results show that cascaded regenerators can efficiently prevent the accumulation of nonlinear phase noise in such systems. It was possible to significantly increase the transmission quality; alternatively, a considerable increase of fiber launch power could be achieved for the same bit-error ratio. As a limiting effect, the amplified Rayleigh backscattering in the highly nonlinear fiber is identified when the regenerator is passed multiple times.

Phase-Preserving Amplitude Regeneration in DPSK Transmission Systems Using a Nonlinear Amplifying Loop Mirror

A phase-preserving 2R regenerator based on a nonlinear amplifying loop mirror was implemented in a RZ-DPSK transmission system. Its performance has been investigated in numerical simulations and experimentally. The results show that amplitude regeneration using a NALM can efficiently prevent accumulation of nonlinear phase noise in a 10 Gb/s DPSK transmission system. In the experiments, significant improvements of eye opening and of BER as well as a 3 dB increase in fiber launch power have been demonstrated. Simulations at 10 Gb/s and 100 Gb/s indicated that the enhancement of the transmission quality is smaller at 100 Gb/s. The reason is that at 100 Gb/s nonlinear intra-channel effects rather than pure nonlinear phase noise are the main limiting factor and the NALM can only reduce the accumulation of amplitude noise in that case.

Q-factor monitoring of optical signal-to-noise ratio degradation in optical DPSK transmission

An asynchronous sampling monitor for optical DPSK signals by using a two-tap histogram is proposed. By means of statistical analysis, a parameter is defined to measure the Q-factor to indicate the OSNR degradation. Compared to traditional monitoring methods, this method requires no synchronisation before sampling and is thus cost-effective.