Performance of Gallium-Erbium Fiber Amplifier in a Double-Pass Configuration

In a previous amplifier setup, a Gallium co-doped Erbium fiber (Ga-EDF) with a length of 2 m has been used as a gain medium. The amplifier which was designed as a single-pass configuration, achieving a highest gain of 22.45 dB. In this paper, the Ga-EDF amplifier is designed as a double-pass setup. The gain and noise figure at the input signal’s wavelength of 1520 nm - 1580 nm is investigated at various input powers, which are from -30 dBm to 0 dBm. This study compares the performance of the amplifiers as it is pumped by a laser signal at the wavelength of 980 nm and 1480 nm, with a power of 140 mW. The amplifier obtained the highest gain of 36.62 dB and 35.77 dB for the pump wavelength of 980 nm and 1480 nm, respectively. The corresponding noise figures are 3.48 dB and 5.01 dB, which occurs at the input signal’s wavelength of 1555 nm. The results indicate that the double-pass Ga-EDF amplifier pumped at 1480 nm outperforms the single pass Ga-EDF amplifier by 15.08 dB, with a comparable noise figure. The results also show that the double-pass Ga-EDF’s performance are comparable at both pump wavelengths

Review on Digital Signal Processing (DSP) Algorithm for Distributed Acoustic Sensing (DAS) for Ground Disturbance Detection

Fiber break because of third-party intrusion has become one of the challenges in maintaining the fiber-based communication link, especially those buried underground. Hence, we investigate the feasibility of using Distributed Acoustic Sensing (DAS) system to sense possible surrounding activities that might cause fiber break. This paper reviews the current digital signal processing (DSP) algorithm used in the DAS system designed to detect ground disturbance, highlighting the specific design parameters for each technique. These parameters include identification rate, classification accuracy, detection accuracy, training time, and signal-to-noise ratio (SNR). The algorithms used are near-field beamforming, phased-array beamforming, image edge detection, gaussian mixture model (GMM), gaussian mixture model - hidden Markov model (GMM-HMM), faster region-based convolutional neural networks (R-CNN), transfer learning, dual-stage recognition network, group convolutional neural network (100G-CNN), and support vector machine (SVM). By reviewing the existing techniques used in the DAS system for ground disturbance detection, we can determine the best DSP algorithm that should be implemented for fiber break prevention, enabling us to design a DAS system specifically for it in the near future

Optical Characterisations of Bi-Phosphosilicate Fiber for O Band Amplification

We report on the optical properties of Bi-doped phosphosilicate fiber. The fiber with a core and a clad diameter of 7.75 µm and 125 µm, respectively, is fabricated in-house using the modified chemical vapor deposition (MCVD) with in-situ solution doping technique. The spectroscopic properties of the fabricated fiber are characterized in terms of absorption, emission and lifetime. The lifetime decay is measured to be 800 µs; indicating a good potential optical amplification in the range of 1300 to 1500 nm. A Bismuth-doped fiber amplifier (BDFA) operating within the O-band region was successfully demonstrated. At 1340 nm, a 14.8 dB gain is achieved with 300 mW pumping power

Effects of bandpass filter bandwidth on multiwavelength Brillouin Erbium Fiber Laser performance

The Brillouin-Erbium Fiber Laser (BEFL) has shown great potential as a multiwavelength source for the dense wavelength division multiplexing system. However, mode competition that exists in the laser cavity confines the wavelength tunability and number of Stokes of the BEFL. In the literature, a Tunable Bandpass Filter (TBF) was adopted in the linear BEFL to improve the tuning range and number of Stokes. This research works examines the effects of different bandwidths of TBF in a multiwavelength BEFL. The linear gain medium was provided by a 13 m long Erbium Doped Fiber (EDF) pumped by a 980 nm laser diode. A 7 km Single Mode Fiber (SMF) was placed in the cavity between the EDF and TBF, and a Brillouin Pump (BP) was externally pumped to produce a non-linear gain from the SMF fiber. The measurements were carried out to study the performance of the multiwavelength BEFL with and without the utilisation of the TBF. Two TBF bandwidths were used in this experiment, namely 3 nm and 1 nm

Double Brillouin frequency shifted L-band multi-wavelength Brillouin Raman fiber laser utilizing dual laser cavity

We experimentally demonstrated a multi-wavelength Brillouin Raman fiber laser with 20 GHz spacing utilizing a dual laser cavity that operated in the L-band wavelength region. In this laser configuration, 11 km long dispersion compensating fiber provided Brillouin gain medium. At Brillouin pump (BP) wavelength of 1580 nm, BP power of 7 dBm and Raman pump power of 1259 mW, 102 Brillouin stokes signals were produced over 14.3 nm of bandwidth. By adjusting appropriate BP wavelength within 1580–1600 nm a tuning range over 20 nm was obtained. In additional, average OSNR of 21.7, 17.8, 16.9, 15.5 and 16.9 dB are recorded for wavelength at 1580, 1585, 1590, 1595 and 1600 nm respectively

Optical Amplifier Utilising Bi-Phosphoslicate Fiber

An optical amplifier utilizing Bi-phosphoslicate fiber producing an on/off gain of 14 dB at 1320 nm. An LD at 1240 nm acting as the main pump providing a maximum power of 200 mW. The length for the fiber under test is 31 m

Tapered optical fibre coated with chitosan for lead (II) ion sensing

This Letter reports a lead (II) ion sensor composed of a tapered multimode fibre (MMF) coated with chitosan. The diameter and length of the tapered fibre region is 20 μm and 1 cm, respectively. Tapered MMF is used because it is more flexible and compact compared with plastic clad silica. Chitosan is chosen as the sensing layer because it can absorb heavy metal ions due to its unique properties as polyelectrolyte and chelating agent. The refractive index of the chitosan layer changes as it absorbs lead (II) ion and this leads to an increase in the absorbance measured by the spectrophotometer. This is tested by immersing the sensor in a solution that contains lead (II) ion with different concentrations, from 0.2 to 1 ppm. The results show that the absorbance measured by the spectrophotometer increased as the concentration of the lead (II) ion increased. The sensor's average sensitivity is measured as 40.554 abs/ppm. This sensor is simpler compared with surface plasmon resonance-based lead (II) ion sensor because it does not require metal coating prior to the sensing layer coating

Effect of bandpass filter bandwidth on the performance of linear cavity multiwavelength BEFL

We have investigated the self-lasing effect of the linear multiwavelength Brillouin-Erbium fiber laser with different tunable bandpass filter's bandwidth. Two 3dB bandwidth of 1 nm and 3 nm filter were used in this study. The experimental results show that the width of the TBF bandwidth plays an important role in shaping the self-lasing effect. By using the tunable bandpass filter with a broader bandwidth, the self-lasing effect can be suppressed efficiently thus producing higher Brillouin Stokes lines. At 0 dBm Brillouin pump power, up to 11 stable output laser channels can be obtained with the utilization of the 3 nm TBF as compared to only 5 output channels with the utilization of 1 nm TBF

Optical Characterisations of Bi-Phosphosilicate Fiber for O Band Amplification

We report on the optical properties of Bi-doped phosphosilicate fiber. The fiber with a core and a clad diameter of 7.75 µm and 125 µm, respectively, is fabricated in-house using the modified chemical vapor deposition (MCVD) with in-situ solution doping technique. The spectroscopic properties of the fabricated fiber are characterized in terms of absorption, emission and lifetime. The lifetime decay is measured to be 800 µs; indicating a good potential optical amplification in the range of 1300 to 1500 nm. A Bismuth-doped fiber amplifier (BDFA) operating within the O-band region was successfully demonstrated. At 1340 nm, a 14.8 dB gain is achieved with 300 mW pumping power

Performance Analysis of an EDFA Utilizing a Partially Doped Core Fiber (PDCF)

The effect of transversal design in Erbium-doped fiber amplifiers’ gain and noise figure performance is illustrated in this work. In this work, we investigate experimentally a single pass 980 nm pumped EDFA with partially doped Erbium core fiber (PDCF), which has the core partially doped with Erbium ions. Later, the enumerated results for PDCF are compared with a standard fully doped EDF, having similar Erbium ion doping concentration. The PDCF Amplifier gain and noise figure performance is studied against different pump power and signal power at different operating wavelengths. The noise figure indicates improvement due to reduced spontaneous emission from un-doped region of the core