We propose and implement a graphene-based composite fiber sensor in this paper. The advantages of this composite fiber lie in simple and practicable fabrication, high sensitivity to tensile strain deformation, wide maximal sensing range. The experiment shows that the composite fiber can monitor small signals of the body and massive movements in conventionality condition such as human pulse and the movement of elbow. This suggests that this graphene-based composite fiber has a broad prospect in health monitoring and movement recognition.
We propose a detection scheme called Stokes vector direct detection (SV-DD) to realize high electrical spectral efficiency and cost-effective optical communication , which is more suitable than coherent detection for short-reach. At reception, the signal is detected in Stokes space.SV-DD is different from conventional DD technique in the parts of not requiring polarization tracking or narrow band optical filtering for carrier extraction. 2nd-order nonlinearity due to photodetection is a fundamental limitation for DD. The conventional SV-DD systems use 2*4 coupler in the receiver, it makes 2nd-order nonlinearity much serious since there are four photodetections or two balance photodetections. In this paper, we experimentally demonstrate the SVDD scheme in single-carrier system using a 3*3 coupler with three photodetections in the receiver.
KEYWORDS: Polarization, Signal detection, Digital signal processing, Telecommunications, Multiplexing, Demultiplexers, Modulation, Eye, Control systems, Beam splitters
A novel scheme for automatic demultiplexing used the partial low frequency radio frequency (RF) power as control
signals for polarization division multiplexed (PDM) system is proposed firstly. The spectrum of detected signals, which
is sensitive to the angle between polarization controller (PC) and the polarization beam splitter (PBS), are thoroughly
analyzed. The effectiveness of this demultiplexing method is experimentally demonstrated.
Compared to other digital equalizers, MLSE (maximum likelihood sequence estimator) equalizer seem to be the most
promising candidate solution to mitigate impairments caused by CD, PMD and fiber's nonlinearity. A novel MLSE
equalizer technology combined with FFE based on nonlinear Volterra theory is investigated, which shows superior
performance for joint compensation of all distortion effects in uncompensated 40Gbit/s Pol-Mux RZ-DQPSK optical
transmission system. The receiver can achieve a long haul transmission with 280 km without any optical dispersion
compensation.
A novel scheme that employing the coherent receiver in atmospheric laser communication system was proposed in this
paper. DPSK format modulation is adopted to overcome atmospheric turbulence and multipath fading. Coherent receiver
is used to improve system's sensitivity. Testing bed was setup and eye diagram can be measured. Real time BER would
be measured soon.
The optical transmission system is being upgraded from 10G to 40G even 100G due to the increasing demands of
wide-bandwidth network. We numerically investigate the nonlinear tolerance of 112 Gb/s polarization-multiplexed
return-to-zero differential quadrature phase-shift keying signal with different types of neighboring channels on a 50-GHz
grid over 1,000 km field fiber. Our transmission result proves showing the feasibility of 100G overlaying existing 10G/40G
commercial systems despite the presence of strong cross-phase modulation.
PM-DQP-ASK is a promising technique to achieve bit rates greater than 100Gbit/s and high spectral efficiency, both
essential for future optical networks.We demonstrated 20 Gbaud PM-DQP-ASK and its successful transmission in a 100
GHz-spaced 10 Gbit/s NRZ-OOK WDM systems over a 768-km transmission link along with the studies of WDM
nonlinear crosstalk.
We proposed an adaptive PMD compensation scheme based on FPGA using DPSO algorithm. Stable polarization
compensation for 43Gbit/s RZ-DQPSK transmission over 1200km was demonstrated with endless polarization
scrambling. Excellent performance was accomplished utilizing our scheme in case of changing SOP and DGD in longhaul
fibre link.
KEYWORDS: Digital signal processing, Polarization, Telecommunications, Analog electronics, Dispersion, Automatic control, Signal detection, Modulation, Polarimetry, Integrated optics
Polarization mode dispersion is considered to be one of the main obstacles for high speed long-haul optical fiber
communication systems. It is necessary to realize PMD monitoring. This paper theoretically analyzed the principle of
polarization mode dispersion monitoring with degree of polarization as monitoring signal. Using the degree of
polarization method, the scheme of DSP based high precision real-time inline PMD monitoring is designed and
implemented. An experiment system is set up to monitor polarization mode dispersion of 40Gbit/s DQPSK system. The
experiment results show that the range of input optical power is -20~0dBm, the response time is 1μs and the states of
polarization accuracy degree is 1%. It has high sensitivity and can be used in a variety of modulation formats and it is
independent of optical signal rate.
We propose and demonstrate a 10Gb/s bidirectional reflective semiconductor optical amplifier (R-SOA) based
wavelength-division-multiplexing passive optical network (WDM-PON) utilizing a DPSK signal for down-link and an
OOK signal re-modulated for up-link. The eye diagram and the penalty of max eye opening factor (EOP) performance of
our simulation results show that the performance of our scheme is as good as those in case of continuous wave(CW) light
injected R-SOA. So our scheme is a practical solution to meet the data rate and cost-efficient of the optical links
simultaneously in tomorrow's WDM-PON access networks.
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