Abstracts:As natural disasters (e.g., earthquake, tsunami, hurricane, etc.) frequently threaten and damage the widely-deployed telecom infrastructure, maintaining the connectivity, transmission bandwidth, and reliability of various service connections becomes a crucial concern in post-disaster telecom networks (such as optical backbone networks). Based on a probabilistic failure model, in this paper we proposed a reliability threshold based service bandwidth recovery (RBR) scheme for recovering the bandwidth and reliability of the impacted service connections after a disaster. Here, the impacted service connections include the ones completely disrupted and/or the ones undisrupted but their reliability decreased beyond the corresponding reference thresholds. Since there is severe lack of bandwidth resource in the post-disaster network, some connections are difficult to obtain enough bandwidth. Under the resource crunch case, RBR employs relaxation policies based on reliability thresholds to explore reliable routes for the impacted connections and to optimize their bandwidth resource utilization. Simulation results show that RBR scheme can make a good trade-off between the bandwidth resource utilization and service connection reliability. It can also achieve satisfactory performance in terms of connection loss ratio, traffic loss ratio, and average connection reliability.

Abstracts:In this work, a compact high energy fiber chirped pulse amplification system with matched pair of a chirped fiber Bragg grating stretcher and a chirped volume Bragg grating compressor is presented. Chirped pulses of 230 ps duration were amplified in a single mode Yb-doped fiber amplifiers to 10 µJ pulse energy and re-compressed to 349 fs duration corresponding to the peak power of 26 MW. Gain saturation was demonstrated when pumping with tandem of single mode laser diodes due to small mode area of the single mode fiber. Such laser source could be used in applications where high peak power is required but moderate average power is sufficient.

Abstracts:In this paper, we present systematic experimental demonstrations of Q-switched all-fiber lasers generating cylindrical vector beam (CVB) outputs with 2D-material-based saturable absorbers, including graphene and black phosphorus (BP). The graphene and BP saturable absorbers are both fabricated by an optically driven method. Both radially and azimuthally polarized CVB laser pulses are realized by adjusting a pair of polarization controllers combined with an offset splice spot and a few-mode fiber Bragg grating. Our experimental effort provides a concise, reliable, and complete all-fiber laser route towards pulsed CVB emissions based on 2D-material saturable absorbers.

Abstracts:In order to develop an efficient, accurate and richly functional intrusion discrimination scheme in the optical fiber perimeter security, this paper proposed a fully modelling based scheme for the DMZI vibration system. In this scheme, data modelling is applied in both the feature extraction stage and the pattern classification stage. By means of incorporating the coefficients of AR modelling into the feature vector, the intrusion characteristics are described in a brief, overall and essential way, which helps to recognize more intrusion types than the existing schemes. Moreover, owing to that the sigmoid modelling is applied in the classifier design, the proposed scheme is endowed with a particular function of estimating occurrence probabilities for all intrusion types. Besides, the adoption of AdaBoostSVM technique further enhances the classification rate. Experimental results showed that, with the above techniques incorporated, our proposed discrimination scheme can identify 6 intrusion types with the average classification rate $87.14\%$ using only 4-length feature patterns, which presents vast potentials for DMZI applications.

Abstracts:Transient response accuracy of the fiber optic seismic accelerometer influences greatly the seismic reservoir monitoring in the smart oilfield fields. This study demonstrates the transient response analysis of an optimized fiber optic seismic accelerometer, and the effects of damping on the transient response are experimentally verified. The silicone oil is injected into the accelerometer structure to increase the damping, and an additional elastic rubber ring is used to provide an adjustable damping. The experimental results show that the injected silicone oil increases obviously the stamper damping, and the variations of torsional moment also modify slightly the damping of the accelerometer. The increase of the damping avoids the oscillation tailing phenomenon, and therefore largely improves the transient response, which is confirmed by the commercial piezoelectric accelerometer. This study can be used to modify the measurement error and improve the accuracy of the seismic reservoir monitoring in the smart oilfield applications.

Abstracts:A non-adiabatic tapered fiber sensor was fabricated, and its applications in refractive index (RI) and temperature sensing were investigated in both theory and experiment. The experiment results demonstrated that the tapered fiber sensor with a diameter of 8 μm had RI sensitivity as high as 1800 nm/RIU and temperature sensitivity of about −300 pm/°C. Then, taking advantage of its high refractive index sensitivity property, an improved temperature sensor structure was proposed by encapsulating it in a glass microtube and filling the microtube with high thermo-optical coefficient liquid. This improved sensor structure showed a higher temperature sensitivity of around −900 pm/°C. The improved sensor structure is simple, low cost and easily fabricated. Besides, this temperature sensor has high sensitivity, good mechanical strength and strong anti-disturbance ability.

Abstracts:A multi-peak detection algorithm based on the Hilbert Transform is proposed to overcome the shortage of traditional single peak detection algorithms, which can extract the Bragg wavelengths from the reflection spectrum in WDM systems. This algorithm introduces the thought of Divide and Conquer, including splitting the reflection spectrum and single peak detection. The multi-peaks can be pre-positioned by splitting the input reflection spectrum after the Hilbert Transform and derivation. Besides, theoretical analysis and the experimental results show that this algorithm using zero as threshold of splitter can greatly enhance the algorithmic portability under different dimensions as well as improve demodulation speed and accuracy. This implies that the proposed algorithm provides a precise demodulation algorithm for the distributed FBG sensor network.

Abstracts:We evaluate the impact of optical amplifier failure on the achievable information rate (AIR) of a transmission link. We consider two scenarios to avoid link failure. First, we consider that after amplifier failure the optical signals are switched to a redundant passive optical line card which surpasses the damage amplifier. Second, we assume that the optical signals are switched to a redundant amplifier card. From the evolution of the AIR with the position in the link where the failure occurs we demonstrate which are the critical amplifiers that demand amplifier cards redundancy to avoid a link failure, and in which place a redundant passive optical line card is admissible. We consider polarization multiplexing (PM) quadrature amplitude modulation (QAM) constellations. To evaluate the AIR, we consider the optical amplified spontaneous emission noise and the nonlinear interference optical noise coherent, as well as the receiver thermal and shot noise sources. Results show that for the first scenario the maximum value attainable by the AIR is strongly dependent on the position of the amplifier failure on the transmission link, being the first amplifiers more critical for the performance of the link. Findings also show that a failure of the last amplifier tends to not affect the AIR. We also observe that it is possible to partially compensate the AIR decrease after an amplifier failure in the first scenario, by optimizing the gain of the remain available amplifiers on the transmission link and by optimizing the transmitter power.

Abstracts:Sensing characteristics of Ho (1, 3 and 5% mol) – doped Bi2O3 clad-modified fibre optic gas sensor are studied for ammonia, ethanol, methanol and acetone gases at ambient temperature. Bi2O3 doped with all concentrations of Ho shows good gas response to acetone, whereas, 1% and 3% mol of Ho show to methanol. Ammonia and ethanol show very poor gas response for all the doping concentrations. The highest gas sensitivity and gas selectivity property are shown with 3% mol of Ho with acetone. Time response characteristics of the sensor are also reported.

Abstracts:Wavelength-selective-switching based reconfigurable optical add-drop multiplexers are the essential components of current and next generation dynamic optical networks. A proof-of-concept 1 × 25 wavelength selective switch is demonstrated experimentally based on liquid crystal on silicon (LCOS) technology and 2-foptical system. Each of the input C-band wavelength channel can be independently selected and switched into arbitrary output ports. The channel passband and channel spacing can be adjusted flexibly by applying holograms onto an LCOS chip. The insertion loss for polarized beam ranges from 5.4 to 7.5 dB for 1–20 output ports and increases up to 9.6 dB at side ports for 100 GHz spaced ITU-T channels over the C-band. The general channel crosstalk is below −20 dB. The minimum resolution of center frequency for each channel is 5 GHz (0.04 nm). The performance can be further improved by using an LCOS chip with smaller pixel pitch, higher-quality optical components and accurate alignment of the fiber-lenslet array.