The bias drift effect in the packaged LiNbO3 modulator is investigated. The Bessel expansion of the dithered clock
shows that the harmonic component equal to the dither frequency can be synchronously demodulated to get the bias drift
and avoid the random phase difference between the clock or data and the dither signal. By using the time division control
method one control system can track two modulator bias drift in 40Gb/s RZ optical transmission system because the
optimum bias point changes very slowly.
Using broadband dispersion compensation CFBGs, over 500km-40Gbps NRZ transmission
system on G.652 fiber will be demonstrated without electric regenerator, FEC and Raman amplifier.
The power penalty is about 2dB @ BER =10-10.The CFBGs have better performance: 3dB band is
about 1.2nm, group delay ripple is less than 25ps near center wavelength, power ripple is less than 2dB,
and DGD is less than 1ps. In order to stabilize the DC bias of the LiNbO3 MZ modulator, a
semiconductor cooler is applied to control the temperature. The effect is perfect.
This paper proposes a single source SBS slow light scheme. This approach splits the incoming pulse train into two beams. One of the beam is used as the "probe"; the other beam is modulated at a frequency which is close to or identical to the half Brillouin shift, and can be used as multiple "pump". The quantitative model shown that the delay and slow light bandwidth can be controlled by the modulation amplitude and the maximum bandwidth is approximately two times of Brillouin shift by choosing an optimum value of the modulation amplitude.
In this paper we mainly discuss the low-cost way to improve the performances of wavelength routed optical networks. It
is really a tough work to reduce the probability of traffic loss due to the lack of abundant lightpath between arbitrary
nodes connected by precious wavelengths. Aiming to solve the problem, we probe an economical proposal that local
optical nodes can be equipped with extra receiving components with cheap Chirp Bragg Gratings. Under the
experimental platform of single-direction double-fibers optical network rings, this scheme has been verified, showing
the result that the traffic loss ratio can be reduced significantly by adding more Chirp Bragg Gratings especially under
heavy service loads. Consequently, it is feasible to improve the performance of all optical networks with several groups
of Chirp Bragg grating fibers with whole consideration of cost-effective optical network design.
In this letter, aiming to obtain the best multicast performance of optical network in which the video conference
information is carried by specified wavelength, we extend the solutions of matrix games with the network coding theory
and devise a new method to solve the complex problems of multicast network switching. In addition, an experimental
optical network has been testified with best switching strategies by employing the novel numerical solution designed
with an effective way of genetic algorithm. The result shows that optimal solutions with genetic algorithm are
accordance with the ones with the traditional fictitious play method.
A simple theoretical model is proposed for the study of timing jitter induced by intrachannel corss-phase modulation
(IXPM) in chirped fiber grating (CFG) compensating systems. The mechanism how CFG reduces the timing jitter is
studied in detail, theoretically and numerically. The reason why symmetrical power and dispersion scheme could
guarantee zero timing jitter is analyzed.
The dispersion of 8×10Gb/s wavelength division multiplex (WDM) system has been compensated by the cascaded chirped fiber Bragg gratings(CFBGs), with ITU-T standard wavelengths and wavelength grid. The ASE of the EDFA could be reduced, the OSNR of the transmitted signal could be increased and the fluctuation of the EDFA gain could be controlled in the certain scope by the dispersion compensated CFBGs' WDM system. Impact of cascaded CFBGs' delay ripple on dispersion compensation has been analyzed. Experiment of error-free 8×10Gb/s 2015km transmission without forward error correction (FEC) and electronic repeaters were demonstrated. In the transmission, simplex CFBGs compensators were used and no other form of dispersion compensators were adopted. The experiment result showed that the consistency of the dispersion compensating in each channel is perfect over 2015km optical fiber transmission. The experiment result does agree with the theoretic analysis.
The formulas for calculating nonlinear phase noise are proposed for both pre-compensation and post-compensation schemes. Based on these formulas, the phase noise, power tolerance and optimal signal peak power of both dispersion compensation schemes are analyzed and discussed in detail, respectively. The result shows that pre-compensation is more effective in reducing the nonlinear phase noise when compared with post-compensation. Its suppression ability improves with signal energy, ASE power spectral density and transmission distance increasing. The pre-compensation system possesses higher power tolerance than post-compensation system and the optimal signal power is increased when dispersion is taken into account, which results that the optimal phase shift is larger than 1rad. And the optimal signal power for pre-compensation system is larger than post-compensation system.
The single-direction, self-healing all optical ring networks with double optical fibers based on the wavelength routing character of fiber gratings is introduced in this paper. The four-node network with ring topology can provide 16×10Gb/s optical transmission. The wavelength-selecting character of chirped fiber gratings is used for wavelength routing, and the function of dispersion compensation and multi-channel add/drop is achieved, too. The SNMP (Simple Network Management Protocol) model is referred to manage this network. Some important parameters are real-time observed to control the network. The results show that, if any optical fiber in the ring is broken down, the interrupted telecommunication service can be recovered automatically in less than 20ms.
In this presentation, the universal structure of one-dimensional photonic crystal (1-D PC) is constructed, and its optical transmission properties are analyzed by transfer matrix method (TMM). A case that there are two kinds of medium as a period is studied in detail. It is concluded that the reflectivity in photonic band-gap (PBG) increases with the increasing of periodical number, and the bandwidth of PBG has direct relation with the difference between two kinds of dielectric constant, three methods for extending PBG are discussed. When defect layer is inserted, a defect mode appears in the PBG. The concept of optimal periodical number is presented, and it is found that this optimal periodical number is only relative to the ratio of dielectric constant (K). Using multi-objective optimization method, we educe the curve and equation relation between optimal periodical number and K for the first time. In addition, the change in the number of defect mode with the variation of the defect layer's thickness is analyzed, and it is explained by the theory of F-P cavity.
A improved train real-time tracing system based on distributed Fiber Bragg Grating sensors is introduced in this paper. Without delicate sensing head, the system can realize the real-time detection of the railway condition and trains' running behavior such as the position, velocity, acceleration, load on axle, number of the axles and so on. To some extent, the system can also implement warning of the train accidents. The system will be significant to the railroad transport.
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