Jihong Cao

40Gbps NRZ transmitted over 500km based on broadband dispersion compensation CFBG

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.

Optical-layer multicast in wavelength-routing network

An optical-layer multicast was studied and implemented efficiently, safely, block-free, and with transparency to data rate and format in a wavelength-routing self-healing network employing chirped fiber gratings and optical circulators.

Modulator bias control based on dither signal in 40Gb/s RZ optical transmission system

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.

Temporal-spectral imaging of optical pulses using time lens

Temporal-Spectral Imaging of optical pulses constitutes a technique for the measurement of fast optical spectral. The experiment to perform real-time spectral analysis of optical pulses in fibre by time lens is demonstrated in this article. The use of time lens in the demodulation of the grating wavelengths is discussed in this article.

Improvement of all optical networks with Bragg grating fibers

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.

Optimization of multicast optical networks with genetic algorithm

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.

Understanding of timing jitter induced by IXPM in CFG compensating optical fiber transmission systems

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.

Novel optical fiber self-healing network based on wavelength routing of fiber gratings

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.

Effect of dispersion compensation schemes on nonlinear phase noise in optical transmission system

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.

Dynamic PMD compensation for 160Gbit/s OTDM systems

By using thin membrane plating technology in collimating lens, we successfully manufacture a 160Gbit/s time-division multiplexer basing on the combination of fiber and space structure method. The multiplexer is flexible according to your practical need, which can output 20, 40, 80, or 160Gbit/s signal. For 20, 40, 80 or 160Gbit/s multiplexer, insertion losses are 4dB, 6dB, 8dB and 16dB respectively. The low insertion loss provides maximum transmission power. It also has such features: polarization insensitivity, very short coherence length, high time-delay accuracy, and excellent temperature stability. An experiment of two degrees PMD compensation in 160Gbit/s RZ optical communication system is achieved. The PMD monitoring technique is based on DOP as error signal. A practical adaptive optimization algorithm was introduced in dynamic adaptive PMD compensation. The experimental results show the improvement in PMD. With this compensator, a significant improvement of system performance can be achieved by auto-correlative curves. The 2.5ps first-order and 15ps2 second-order PMD are compensated. The PMD compensating time is less than 100ms.