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A temperature-insensitive magnetic field sensor with high interrogation performance and large measurement range based on an optoelectronic oscillator (OEO) merging a Mach–Zehnder interferometer (MZI) is proposed and experimentally demonstrated. In the OEO loop, a finite impulse response (FIR)-microwave photonic filter (MPF) and an infinite impulse response-MPF are cascaded to select the oscillating frequency and further suppress the side mode. The center frequency of the FIR-MPF, which is composed of a non-coherent broadband optical source, a MZI, a dispersion compensating fiber (DCF), and a photodetector, is determined by dispersion of DCF and the free spectral range (FSR) of the MZI jointly. In one arm of the MZI, a section of optical fiber is bonded with a giant magnetostrictive material (GMM) to achieve the magnetic field sensing, where the GMM is acted as a magnetic field-strain transducer. When the magnetic field varies, the FSR of the MZI will be changed, resulting in an oscillating frequency shift of the OEO. Therefore, a high interrogation performance magnetic field measurement can be achieved by simply monitoring frequency change of microwave signal generated by OEO in the microwave domain. Moreover, by placing a section of unprocessed fiber with appropriate length in the other arm of the MZI, the temperature cross-talk for the magnetic field can be alleviated greatly. In the experiment, the magnetic field sensitivity of 1.33 MHz/mT with a large range of 20.9 mT to 58 mT is obtained and the measurement error induced by temperature is as low as 0.09 mT.

Here are many challenges for target detection in the complex scenes. In the real scene, such as the diversity of the type, quantity and shape of the parts on the workpiece plates, the model construction and rapid detection need to deal with the complex and changeable scene, and the large-scale massive point cloud data challenges the operational efficiency and accuracy of visibility analysis technology. In this paper, the 3D modeling method based on computer graphics is proposed by using the displacement laser sensor as the digital representation of 3D complex scene on the scanning point cloud, which realizes the fast extraction of semantic target feature parameters under complex conditions. The multi-dimensional parameter-based saliency feature and fusion multiple filtering algorithm is built to obtain a fast and high-precision intelligent template recognition detection method. Based on SOC embedded engineering technology, the detection algorithm is realized by software programming. The two-dimensional mechanical motion platform is developed to test the workpiece plate applied to wheel hub of high-speed rail train, and the recognition accuracy is more than 99%.

This paper reports that the effect of Co 60 gamma-radiation on the attenuation variation of rare earth doped fibers – Er-Al codoped fiber and Yb-Al codoped fiber. These fibers were fabricated using modified chemical vapor deposition method in the ILT lab. The team has found that in contrast with standard single mode fiber, the rare earth fibers have twenties times more ability of anti radiation. And the attenuation increment/decrement rates for radiation/recovery of all kind of fibers is depending on type and operating wavelength band of fiber. The experiment results show that the Al-doped fiber has highest ability of anti radiation and the Er-Al codoped fiber has better recovery ability from radiation.

A strain sensor implemented by cascading a Sagnac interferometer (SI) and a fiber modal interferometer (FMI) was proposed and experimentally demonstrated. The SI serving as the fixed part comprises a length of polarization maintaining fiber (PMF), and the FMI serving as the sliding part comprises single mode fiber (SMF) and a length of few mode fiber (FMF) with core-offset structure. By closing the free spectral ranges (FSRs) of the SI and FMI, Vernier-effect exists and makes contribution to magnify the sensitivity. Through monitoring the FSR of the spectral envelope, the strain sensing is realized. A high sensitivity of 65.71 pm/μe which is more than 20 times higher than that of the single FMI is obtained experimentally. Moreover, thanks to the polarization insensitivity of FMF, the proposed sensor is immune to environmental disturbance and suitable for physical sensing applications.

The characteristics of chirped fiber Bragg gratings (CFBGs) are optimized so that the ripple coefficient of the power reflectivity spectrum and group time delay are less than 1 dB and |± 15| ps, group delay is about 2600 ps/nm, polarization module dispersion is very small, PMD

In this paper, a theoretical model is proposed for the analysis of timing jitter induced by intrachannel interactions in optical fiber communication systems using chirped fiber grating (CFG) as dispersion compensator. And for the first time, the impact of group-delay ripple (GDR) on timing jitter is taken into account in detail, theoretically and numerically. Results show that the GDR may increase or decrease the timing jitter of certain pair of adjacent pulses, deciding by the ripple parameters. The maximum influence will be obtained when ripple period is about 2/5 of the input pulse width. In practical systems, the GDR enhance the timing jitter for some adjacent pulses while reduce it for some other adjacent pulses, depending on the pulse pattern and the GDR parameters. In our simulation, the GDR guarantees a 3.04 ps increase of the standard deviation of the timing jitter.

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 8 × 10 Gb/s 2 560 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 2 560 km error-free experiment. The results also show that CSRZ will help to optimize the transmitted results and reduce the transmitted penalty further.

The cascaded chirp fiber Bragg gratings (CFBGs) with ITU-T standard wavelengths and wavelength grid are applied to compensate the dispersion of 8×10 Gb/s WDM system. The ASE of the EDFA could be reduced, the OSNR of the transmitted signal can be increased and the fluctuation of the EDFA gain can be restrained in a certain scope by the CFBG employed in the system. Experiment of error-free 8×10 Gb/s 2015 km transmission without FEC and electric regeneration is demonstrated in this paper. In this system, only EDFA is used as amplifier, and no other form of dispersion compensator is adopted except CFBG. The experimental result showed that after 2015 km transmission, the consistency of the dispersion compensating for each channel is perfect.

Based on linear-system theory, a method to obtain the total group-delay characteristics of the cascaded chirped fiber Bragg grating (FBG) from the measured group delays of each grating is proposed. The method is then used to characterize cascaded chirped FBGs used as the dispersion compensators of an experimental eight-channel 10-Gb/s NRZ system over 1500-km G.652 fiber. The inband total local-dispersion deviation curve is calculated and shows good consistency with the tendency of the inband BER fluctuations, which indicates that the inband local dispersion deviation may be the main reason for the dependence of such a system performance on signal wavelength, and its RMS value can be taken as the indicator of performance tolerance to wavelength instability. Numerical simulation is also performed, by which a near linear scaling of the simulated EOP with total local-dispersion deviation is shown. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 343–346, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21165

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.

The bias drift effect in the packaged LiNbO 3 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. Keywords: LN modulator, bias control, optical transmission system, dither signal 1. INTRODUCTION In order to improve the receiver sensitivity or enhance the tolerance for chromatic dispersion and polarization mode dispersion, coding format is one of the most important factors in designing optical fiber transmission system. Return-to-zero (RZ) formats with various modulation techniques have better performance than conventional nonreturn-to-zero (NRZ) format 1,2,3,4 . Therefore, Multiple LiNbO

The effect of non-ideal dispersion and reflection characteristics of chirped fiber Bragg gratings (CFBG) on the 40-Gb/s and 10-Gb/s transmission is investigated. The effect of group delay ripple (GDR) on eye-opening penalty (EOP) of carrier-suppressed return-to-zero (CSRZ) and return-to-zero (RZ) formats is analyzed and compared. The system penalty for different amplitude and period ripples are quantified.

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.

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.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

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.

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.

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.

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 15ps 2 second-order PMD are compensated. The PMD compensating time is less than 100ms.

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.

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 dyeing of silk fabric with liquid sulphur dyes has been investigated. The results show the dyeings with good exhaustion and colour fastness are theoretically possible. Under weakly alkaline, low–temperature dyeing conditions damage to silk fabric was slight.

We report on a 40 Gbit/s NRZ (non-return-to-zero) code transmission experiments including an dynamic Polarization mode dispersion (PMD) compensation. The dynamic PMD compensator is made up of two-stage four degrees. The first stage adopts polarization controller and fixed time-delayed line. The second stage is variable Differential Group Delay (DGD) element. The PMD monitoring technique is based on degree of polarization (DOP) as error signal. A novel practical adaptive optimization algorithm was introduced in dynamic adaptive PMD compensation. The experimental results show that the performance of the PMD compensator is excellent for 40Gbits/s NRZ transmission systems with the large the DGD. With this compensator, a significant improvement of system performance can be achieved in the eye pattern of a received signal.

A modified carrier suppressed return-to-zero (CSRZ) format was forward in this paper, and it helps to improve the extinct ration (ER) and signal-to-noise ration (SNR) of the transmitted signal. Experiment of 2560km error-free transmission in straight line without forward error correction (FEC) and electric regeneration was demonstrated in this paper to evaluate the performance of modified CSRZ, and chirped fiber Bragg grating (CFBG) employed as the dispersion compensator in this transmission system. The experiment result showed that if the modified CSRZ format was applied in this 2560km transmission, less than 2.5dB power penalty was cost after 2560km transmission, and on the other hand, error-free transmission could not be got in the conventional NRZ-based CFBG-compensated system.

Using dispersion compensation CBG, 2500km-10Gbps RZ and CSRZ transmission system on G.652 fiber is successfully demonstrated without electric regenerator and without Raman amplifier. At 2080km and 2560km, power penalty for RZ is about 3dBm and 5dBm (condition: RZ signal, BER=10 -12 , PRBS=10 23-1 ); And power penalty for CSRZ is about 1dBm and 3dBm. The result indicates it is superior to the system using CSRZ signal under same condition.

Group velocity delay ripple (GDR) and reflectivity ripple (RR) are the main nonideal characteristics for chirped Bragg fiber grating (CFBG). The influence of these nonideal characteristics on the CFBG-based transmission systems with carrier suppressed return-to-zero (CSRZ) format was investigated, and the performance of the transmission system was evaluated by the eye opening penalty (EOP) in this paper. In additional, the impact of the phase difference between the central wavelength of the transmitted signal and the GDR on the transmission system which make the transmission performance fluctuate randomly was also studied. The analysis helps to conduct a practical 10Gb/s 2560km error-free transmission experiment in straight line with low power penalty, and no electronics regenerator and forward error correction (FEC) were employed in this system. The experiment result is so attractive in long haul transmission field.

Dynamic programming, the ordinary adaptive compensation in the operational research, is used to resolve extremum of functions under the constraint condition. In this paper, it is introduced that, fundamentals, methods and steps about the first-order PMD compensation by dynamic programming. The result shows that, for the first-order PMD compensation, dynamic programming is used to carry out optimized design, and the result is satisfied. Beginning with recursive relation of PMD vectors in the fiber and the compensation devices, mathematical model of the first-order PMD compensation is established. Through optimized algorithm using dynamic programming, simulation and experiment for PMD adaptive compensation are both implemented. Some optimized algorithms once used in the PMD adaptive compensation have slow speed to approximate the optimal value and tends to become the local optimal solution; but if optimized algorithm using dynamic programming can approximate the global optimal solution directly. Therefore, it has the advantage of fast optimized speed. On this basis, the image of optimal solution is given and analyzed. PMD compensation scheme, based on PMD compensation vector, is proposed. The algorithm principle of adjusting control and the direction of improvement are also put forward. These results are benefit for dynamic adaptive compensation of PMD.

A novel wavelength-routing all-fiber 10Gb/s WDM network with four nodes in a ring topology is forwarded, and at each node data can be transmitted at different wavelength according to the destined node which it wants to transmit. The main character of the system is that the stable-packed chirp fiber Bragg gratings (CFBG) used in this network utilize two functions: route and dispersion compensation. Meanwhile, a modified measuring method of power penalty including cross-talk penalty, ASE penalty and dispersion penalty is illustrated, and the experiment conducted in this paper shows the measuring method can be perfectly applied in this wavelength-routing all-fiber WDM network system mentioned above. All these measures ensure that optimum system performance would be achieved.