Design and Development of a Fiber Break Monitoring System in Optical Fiber Communications

Fiber optic cable has been used widely in network communications system.It has being a favorable choice since it offers many advantages,such as immunity to electrical interference, lightening, high bandwidth and security. Due to the massive deployment of optical fiber cable, networks based on this medium needs significantly good monitoring and protection scheme to ensure its availability, especially for critical networks.Current approach uses a system known as Remote Fiber Testing System (RFTS) or Remote Fiber Monitoring System (RFMS).RFMS allows an operator to remotely monitor the condition of a fiber cable by using Optical Time Domain Reflectometer (OTDR). The requirements to place OTDR permanently for continuous monitoring force the line owners to place a high investment to the system.Moreover, placing OTDR is overkill since most of the faults in the fiber optic cable are due to the fiber break.This thesis presents a new approach of monitoring and detecting fiber break by using a simpler device, significantly less expensive yet gives an appropriate measurement to the distance break in place of the OTDR–based RFMS. The design and development of the system, namely Fiber Break Monitoring System (FBMS) will continuously monitor the optical signals in the live fiber cable. The device automatically measures the distance when it detects the break. The distance is measured by analyzing the propagation time of the Fresnel reflection, occurred at the end of the surface break to be detected by the detector module inside FBMS. The study is carried out in both simulation and experiment. The typical performances for analyzing the performance of FBMS are the length resolution, event deadzone, sampling resolution, accuracy, dynamic range and pulsewidth. Those performances were compared to the typical OTDR. This study has proved that FBMS is practicable for a real time monitoring, detecting a fiber break and giving an acceptable result to the distance measure

Assessment of Student Program Outcomes through a Comprehensive Exit Strategy

AbstractChoosing methods to assess student program outcomes is a matter of balancing best practices against the constraints imposed by the respective education authorities mainly the Engineering Accreditation Council (EAC) for engineering degrees offered by institutions of higher education in Malaysia. Methods that directly measure student learning and yield the most rigorous results are usually the most time consuming and may require the expertise of educational researchers or outside consultants. Currently, the Department of Electrical, Electronics and Systems Engineering at UKM use their classroom and existing grading practices to collect data that will contribute to assess student learning directly, but this requires extra time and effort. In addition, mechanisms to adequately report the findings need to be properly implemented. Another mechanism that could be used to assess student program outcomes is through a thoroughly designed student exit strategy. The exit strategy implemented this academic year involves two parts; exit survey and exit test. This is a Continuous Quality Improvement (CQI) effort done since the past two academic years that enables the department to assess student program outcomes directly and indirectly in one approach. The exit strategy has proven successful as a valid measurement of student program outcomes. The exit strategy which combines both direct and indirect assessment forms a comprehensive and robust tool to effectively measure student program outcomes

Enhancement of chitosan-graphene oxide SPR sensor with a multi-metallic layers of Au–Ag–Au nanostructure for lead(II) ion detection

We demonstrate the enhancement of surface plasmon resonance (SPR) technique by implementing a multi-metallic layers of Au–Ag–Au nanostructure in the chitosan-graphene oxide (CS-GO) SPR sensor for lead(II) ion detection. The performance of the sensor is analyzed via SPR measurements, from which the sensitivity, signal-to-noise ratio and repeatability are determined. The nanostructure layers are characterized using field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). We showed that the proposed structure has increased the shift in the SPR angle up to 3.5° within the range of 0.1–1 ppm due to the enhanced evanescent field at the sensing layer-analyte interface. This sensor also exhibits great repeatability which benefits from the stable multi-metallic nanostructure. The SNR value of 0.92 for 5 ppm lead(II) ion solution and reasonable linearity range up to that concentration shows that the tri-metallic CS-GO SPR sensor gives a good response towards the lead(II) ion solution. The CS-GO SPR sensor is also sensitive to at least a 10−5 change in the refractive index. The results prove that our proposed tri-metallic CS-GO SPR sensor demonstrates a strong performance and reliability for lead(II) ion detection in accordance with the standardized lead safety level for wastewater

Single-stage gain-clamped L-band EDFA with C-band ASE self-oscillation in ring cavity

We demonstrate single-stage gain-clamped L-band Er3+-doped fiber amplifier (EDFA) utilizing self-oscillation modes as the control light. The amplifier structure exploits the characteristics of C/L-band coupler to isolate between lasing modes and L-band signal. The self-lasing cavity modes are obtained without any tunable bandpass filter in the loop and generated from the amplified spontaneous emission in the C-band region. The amplifier configuration has lower noise figures as opposed to a dual-stage partially gain-clamped amplifier. The gain and noise figure fluctuations are less than ±0.4 dB in the gain clamping region. The transient analysis confirms that the maximum power excursion is less than 0.3 dB for 10-dB add/drop

Analytical study of nonlinear phase shift through stimulated Brillouin scattering in single mode fiber with the pump power recycling technique.

We present a theoretical study of nonlinear phase shift through stimulated Brillouin scattering in single mode optical fiber. Analytical expressions describing the nonlinear phase shift for the pump and Stokes waves in the pump power recycling technique have been derived. The dependence of the nonlinear phase shift on the optical fiber length, the reflectivity of the optical mirror and the frequency detuning coefficient have been analyzed for different input pump power values. We found that with the recycling pump technique, the nonlinear phase shift due to stimulated Brillouin scattering reduced to less than 0.1 rad for 5km optical fiber length and 0.65 reflectivity of the optical mirror, respectively, at an input pump power equal to 30mW

Detection of back-scattered signal for optical fibre resonant scanner

We report the development of optical fibre resonant scanner that was developed using two multi-mode optical fibres that are attached side-by-side, producing a cantilevered optical fibre scanner. The optical fibre is mounted on photodiode and a small piezoelectric disk using polymer. The piezoelectric disk is driven with a sinusoidal signal that will then vibrate the mounted optical fibre, producing a single axis scan line. This paper reports on experimental detection of the back-scattered signal through dual-numerical aperture conFigureuration and identification of fibre position from a single scan line with respect to the optical reflections from the apertured reflector. The apertured reflector used was a brass metal with 1 mm of diameter that is placed before the imaging lens as a mechanism to differentiate the position of scan line. The single scan was obtained at its maximum length of 4.8mm with resonant frequency of 2.033kHz. The back-scattered signal from a target object is coupled back into the cladding of the optical fibre. The cladding mode is then stripped and detected by photodiode. The back scattered signal from the aperture is used to differentiate the position of fibre between the aperture and the target object itself. Differences in the position of the slots resulted pulses with different height and width, allowing the two backscattered signals to be distinguished. The experimental result is verified and compared with the theory back-scattered signal produced by such scanner

Multiwavelength Brillouin-Raman ring-cavity fiber laser with 22-GHz spacing.

We experimentally demonstrate a multi-wave length Brillouin-Raman fiber laser configured in a ring-cavity resonator. Interactions between stimulated Brillouin scattering and Raman amplification in a dispersion compensating fiber, attributed to the generation of 16 output channels at injected Raman pump unit power of 650 mW and Brillouin pump power of 2.0 mW. The first output channel has a peak power of 14.8 mW. By discriminating the even-order Brillouin Stokes signals from circulating in the resonator, the generated output channels were found to have wavelength spacing of ∼22 GHz. The output channels were also found to have average optical signal-to-noise ratio value of 11.7 dB

Single stage gain-clamped L-band EDFA with C-band ASE saturating tone.

We demonstrate a single-stage gain-clamped L-band Erbium-doped fiber amplifier with 1480 nm pump wavelength. The gain-clamping technique is achieved by utilizing the backward propagation of C-band amplified spontaneous emission (ASE). This unwanted noise is reflected back into the optical amplifier and its intensity is adjusted using the variable optical attenuator. The C-band ASE sets the population inversion level along the Erbium doped-fiber and limits the L-band signal amplification to a specific value. The whole optical bandwidth in L-band can be employed for signal amplification since the saturating tone is out of the band. The gain dynamic range of 11.7 dB is obtained between 21.7 and 10.0 dB with noise figure of less than 5.5 dB for signal power up to 2 dBm

Opto-optical gain-clamped L-band Erbium-doped fiber amplifier with C-band control signal

We demonstrate an opto-optical gain-clamped L-band erbium-doped fiber amplifier by manipulating the C-band lasing wavelength as the control signal. The L-band gain-clamped value is achieved by tuning the control laser in the C-band wavelength range that propagates in the opposite direction to the L-band signal. Within the wavelength range of 1538 nm and 1560 nm , the L-band gain decreases linearly with the increment of the C-band lasing wavelength. The L-band gain dynamic range decreases with the increment of the cavity loss. By combining two different levels of cavity loss, the gain dynamic range of 10 dB from 11 dB to 21 dB is achieved with an average noise figure of less than 5.9 dB . The whole gain spectrum of the L-band can be used for multiple-channel amplification because the laser is created outside its signal band

Motion Artifacts Correction from Single-Channel EEG and fNIRS Signals using Novel Wavelet Packet Decomposition in Combination with Canonical Correlation Analysis

The electroencephalogram (EEG) and functional near-infrared spectroscopy (fNIRS) signals, highly non-stationary in nature, greatly suffers from motion artifacts while recorded using wearable sensors. This paper proposes two robust methods: i) Wavelet packet decomposition (WPD), and ii) WPD in combination with canonical correlation analysis (WPD-CCA), for motion artifact correction from single-channel EEG and fNIRS signals. The efficacy of these proposed techniques is tested using a benchmark dataset and the performance of the proposed methods is measured using two well-established performance matrices: i) Difference in the signal to noise ratio ({\Delta}SNR) and ii) Percentage reduction in motion artifacts ({\eta}). The proposed WPD-based single-stage motion artifacts correction technique produces the highest average {\Delta}SNR (29.44 dB) when db2 wavelet packet is incorporated whereas the greatest average {\eta} (53.48%) is obtained using db1 wavelet packet for all the available 23 EEG recordings. Our proposed two-stage motion artifacts correction technique i.e. the WPD-CCA method utilizing db1 wavelet packet has shown the best denoising performance producing an average {\Delta}SNR and {\eta} values of 30.76 dB and 59.51%, respectively for all the EEG recordings. On the other hand, the two-stage motion artifacts removal technique i.e. WPD-CCA has produced the best average {\Delta}SNR (16.55 dB, utilizing db1 wavelet packet) and largest average {\eta} (41.40%, using fk8 wavelet packet). The highest average {\Delta}SNR and {\eta} using single-stage artifacts removal techniques (WPD) are found as 16.11 dB and 26.40%, respectively for all the fNIRS signals using fk4 wavelet packet. In both EEG and fNIRS modalities, the percentage reduction in motion artifacts increases by 11.28% and 56.82%, respectively when two-stage WPD-CCA techniques are employed.Comment: 25 pages, 10 figures and 2 table