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Performance analysis of long band passive optical network using amplifier spontaneous noise and fiber Bragg gratings
Abstract
Long band (L-Band) passive optical networks (PONs) are attracting a lot of attention these days, thanks to rising capacity demands. Because of PONs requesting more and more channels, fault detection/monitoring is critical. Fault detection in the conventional band (C-Band) employing reflecting Fiber Bragg Gratings (FBGs) and a probe signal integrating an additional amplified spontaneous noise (ASEN) source has been frequently demonstrated. However, interference occurs when ASEN and transmitter signals are in the same wavelength band, and adding additional ASEN sources to the network raises the overall cost. So, in L-Band PONs, a cost-effective, low-complexity fault detection/monitoring system is required. Therefore, in this work, a fault detection/monitoring system for L-Band PON using C-Band ASEN from inline erbium doped fiber amplifier (EDFA) and dual purpose FBG, i.e. (1) ASEN reflection for fault monitoring and (2) dispersion compensation is proposed. A 4 × 10 Gbps L-Band PON is investigated over 40 km feeder fiber (FF) and 1 km drop fibers (DFs) that serve 32 optical network units (ONUs)/different input powers, dispersion values, and laser linewidths in terms of reflective power of FBGs, eye opening factor, and bit error rate (BER), respectively.
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In this study a technique for a centralized fault monitoring and detection in Gigabit-capable Passive Optical Network (G-PON) using fiber Bragg grating (FBG) sensor is proposed. The technique detects fault once it occurs at the vulnerable locations in the fiber optic distribution link by the proposed FBG devices. Monitoring signal in the C-band is reflected by a uniform FBG with different Bragg wavelengths and reflectivities. The FBGs serve as branch identifiers in the network. The reflected signal from the FBGs is analyzed at the Optical Line Terminal (OLT) in the Central Office (CO) by an Optical Spectrum Analyzer (OSA), to identify the branch with rupture in the network. The simulated result obtained shows that the system can monitor, and detect a fault in the physical layer of the optical distribution network with negligible effects on data signal transmission.
A scheme for mitigation of Rayleigh backscattering in RoF-WDM-PON with self-coherent detection by using bi-directional crossed network has been projected and investigated. In this paper, 10 Gbps 16-QAM signal transmits via two different carrier frequencies for downstream and upstream transmission, such that impairment due to re-modulation noise can be mitigated effectively in upstream transmission. This architecture increases the tolerance limit against Rayleigh backscattering noise as it does not allow the signals of same wavelength to propagate through a same feeder fiber. Less noisy information for wired link and 15 m wireless link are detected by homodyne and heterodyne detection respectively in coherent detector. Reliability of the proposed scheme is evaluated by low bit-error-rate, low error vector magnitude, low power penalty, clear constellations and open eye diagrams. Therefore, acceptable performance of the proposed system proves the potential to be a prominent solution for optimising noise and also it has application even in platform of multiservice network in communication field.
It is 21 years since the first passive optical network (PON) was standardized as an asynchronous transfer mode passive optical network (APON) with same optical distribution network scheme as we know in current networks. A lot of PON networks were standardized in the following years and became an important part of telecommunication. The general principles of these PON networks are described in many papers and books, but only a little information about used lasers is available. The aim of this tutorial is to describe lasers used in PON networks and principles of their operation. The paper describes the principles of single longitudinal mode (SLM), multi longitudinal mode (MLM), distributed-feedback (DFB), and Fabry–Pérot (FP) lasers. Furthermore, the lasers are compared by their usage in optical line termination (OLT) for passive optical networks. The second part of this tutorial deals with activation process of optical network unit. The described principle is the same for connection of a new customer or blackout scenario. The end unit is not able to communicate until reach the operational state; each state is defined with physical layer operation and administration and maintenance (PLOAM) messages sequence and their processing.
Fiber Bragg grating has embraced the area of fiber optics since the early days of its discovery, and most fiber optic sensor systems today make use of fiber Bragg grating technology. Researchers have gained enormous attention in the field of fiber Bragg grating (FBG)-based sensing due to its inherent advantages, such as small size, fast response, distributed sensing, and immunity to the electromagnetic field. Fiber Bragg grating technology is popularly used in measurements of various physical parameters, such as pressure, temperature, and strain for civil engineering, industrial engineering, military, maritime, and aerospace applications. Nowadays, strong emphasis is given to structure health monitoring of various engineering and civil structures, which can be easily achieved with FBG-based sensors. Depending on the type of grating, FBG can be uniform, long, chirped, tilted or phase shifted having periodic perturbation of refractive index inside core of the optical fiber. Basic fundamentals of FBG and recent progress of fiber Bragg grating-based sensors used in various applications for temperature, pressure, liquid level, strain, and refractive index sensing have been reviewed. A major problem of temperature cross sensitivity that occurs in FBG-based sensing requires temperature compensation technique that has also been discussed in this paper. © 2020 Society of Photo-Optical Instrumentation Engineers (SPIE).
We present a low-cost embedded Optical Time Domain Reflectometer (OTDR) solution for link monitoring of direct modulation analog Radio over Fiber (a-RoF) systems transporting Long Term Evolution Advance (LTE-A) signals. Experimental results show that monitoring can be performed in-service and offline in order to detect fiber faults and quantify losses. A trade-off between the OTDR peak power and the data transmission power has been identified; nevertheless, it is proven that with proper configuration of the system, the required values of Error Vector Magnitude (EVM) for different modulation formats are not surpassed. Offline monitoring using this configuration setup showed a Dynamic Range of ~24 dB with 10 meters spatial resolution.
Optical link fault detection and localization are significant in the Passive optical network (PON) due to the passive nature of the network elements involved. A single failure in the optical link can resort to a huge amount of data loss in the network. However, deployment of fault detection and localization devices is extremely limited due to the extra cost network operators need to pay and the reliability of the devices. PON fault monitoring solutions have been investigated by the researchers over the decades; the challenges for these monitoring techniques are the cost and complexity of their deployment. Thus, this work proposes a technique for the detection and localization of fault in the optical link of a PON Fiber-to-the-x (FTTx) network using optical reflectors. The real-time back-reflected signal from the reflectors in the network will be utilized to determine the optical link with fault. Experimental results obtained show that multiple optical link impairments can be detected and localized in the PON FTTx based network in-service, over a distance of 20 km, in a cost-effective manner. Measurements from a standard Optical Time-Domain Reflectometer (OTDR) is used to prove the validity of our technique.
An enhanced triple-pass hybrid optical fiber amplifier in a dual-stage configuration is presented
by utilizing a combination of hafnium-bismuth erbium-doped fiber (HB-EDF) and bismuth erbium-
doped fiber (Bi-EDF) as gain medium. The total Erbium-doped fiber length was only
199 cm, and both HB-EDF and Bi-EDF were forward pumped by 1480 nm with an optimum pump
power of 170mW and 110 mW, respectively to provide flat gain and wideband amplification. At
high input power of -10 dBm, a flat gain of about 19 dB with gain fluctuation of less than 2 dB was
observed over wideband ranging from 1555–1600 nm. On the other hand, the noise figure varied
from 4.8–9.3 dB within the flat gain region. The triple-pass Erbium-doped fiber amplifier has
been enhanced by utilizing distribution pumping scheme in the configuration. This improvised
configuration minimised the cost of the amplifier yet having the comparable performance with
the dual-pump configuration. A flat gain of 17.2 dB with the corresponding noise figure below
8 dB was obtained within 1555–1600 nm.
We demonstrated a full duplex hybrid passive optical network and indoor optical wireless system employing coherent optical frequency division multiplexing. To accomplish reliable transmission in passive optical networks integrated visible-light communication (VLC), yellow light-emitting diode and infrared LED is used in downstream and upstream, respectively, for intra building network. In order to support high data rate, pulse-width reduction scheme based on dispersion compensation fiber is incorporated and system successfully covered the distance of 50 km. A data stream at the rate of 30 Gb/s is transmitted for each user out of eight users. VLC-supported users are catered with the bit rate of 1.87 Gb/s over 150 cm and in order to realize a low-cost system, visible and infrared LEDs are used in downlink and uplink, respectively.
This paper presents a centralized and fault localization technique for Ethernet Passive Optical Access Network. This technique employs L-band Amplified Spontaneous Emission (ASE) as the monitoring source and various fiber Bragg Gratings (FBGs) as the fiber's identifier. An FBG with a unique combination of Bragg wavelength, reflectivity and bandwidth is inserted at each distribution fiber. The FBG reflection spectrum will be analyzed using an optical spectrum analyzer (OSA) to monitor the condition of the distribution fiber. Various FBGs reflection spectra is employed to optimize the limited bandwidth of monitoring source, thus allows more fibers to be monitored. Basically, one Bragg wavelength is shared by two distinct FBGs with different reflectivity and bandwidth. The experimental result shows that the system is capable to monitor up to 32 customers with OSNR value of ∼1.2 dB and monitoring power received of −24 dBm. This centralized and simple monitoring technique demonstrates a low power, cost efficient and low bandwidth requirement system.
We explore the performance of a tunable optical time domain reflectometer based on single photon detection for fault location and quantification in wavelength division multiplexing (WDM)-passive optical networks based on a 32-channel cyclic arrayed waveguide grating using the S- and C-bands for upstream (156 Mb/s) and downstream (2.5 Gb/s) transmission and the L-band for monitoring. Downstream Rayleigh and Raman scattering contributions to the dark count noise were evaluated and properly filtered out with a total WDM + filter rejection ratio of 90 dB. Upstream power was found to generate the greatest contribution to the noise floor and is the limiting factor to the upstream transmission data rate. In-service monitoring experiments with full upstream and downstream power show that the proposed scheme is able to achieve dynamic range levels of up to 32 dB with 5-m spatial resolution and no measurable penalty in data transmission.
A new technique of fiber-break detecting and monitoring in optical communication network systems is proposed and experimentally demonstrated. The subsystem, namely fiber-break monitoring system is designed to be simpler, significantly less expensive and yet gives an appropriate measurement to the distance break in place of the optical time domain reflectometer. This new approach has a bright prospect to be utilized in existing optical communication network systems. The proposed technique gives a minimal insertion loss of 1.7 dB and measurement accuracy of 0.285 km.
We propose and demonstrate a new in-service fault-localization method for a wavelength division multiplexing passive optical network (WDM-PON). This scheme uses a tunable OTDR realized by a wavelength-locked Fabry-Perot laser diode. We successfully detect the faults both at the feeder fiber and the drop fibers. The resolution and the dynamic range are 100 m and 12 dB, respectively. In addition, the crosstalk induced by the OTDR signal to the transmission data is negligible. (c) 2007 Optical Society of America.
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