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Fiber to the home (FTTH) passive optical network is one of the cost effective and effortlessly planning systems in the current era of communication systems. However, one of the substantial limitations of this optical communication network is the monitoring operation. It is essential to locate the fault branch in the network in order to take the required action to overcome the problem. Unfortunately, since the network is all passive, it is necessary to introduce a technique that should be passive and has the capacity to locate the fault location inside the network. In this paper, a methodology to localize the fault line was introduced, where a combination of Fiber Bragg Gratings was suggested, using this approach, the fault location can be easily determined among 36-branch, distributed in eight groups. Simulation results show that the broken line can be determined through monitoring the reflected signals from all the branches in the Central Office without paying any power to locate the leakage. In other words, it is easy to recognize the fault location by monitoring the power of the reflected signals, where after comprehensive simulations and power calculations, it was possible to put a threshold for that reflected power, hence, the fault branch, for any reason, may reflect power of less than that threshold, otherwise, the branch is not considered as broken.

The Intrusion Detection System (IDS) is an important feature that should be integrated in high density sensor networks, particularly in wireless sensor networks (WSNs). Dynamic routing information communication and an unprotected public media make them easy targets for a wide variety of security threats. IDSs are helpful tools that can detect and prevent system vulnerabilities in a network. Unfortunately, there is no possibility to construct advanced protective measures within the basic infrastructure of the WSN. There seem to be a variety of machine learning (ML) approaches that are used to combat the infiltration issues plaguing WSNs. The Slime Mould Algorithm (SMA) is a recently suggested ML approach for optimization problems. Therefore, in this paper, SMA will be integrated into an IDS for WSN for anomaly detection. The SMA’s role is to reduce the number of features in the dataset from 41 to five features. The classification was accomplished by two methods, Support Vector Machine with polynomial core and decision tree. The SMA showed comparable results based on the NSL-KDD dataset, where 99.39%, 0.61%, 99.36%, 99.42%, 99.33%, 0.58%, and 99.34%, corresponding to accuracy, error rate, sensitivity, specificity, precision, false positive rate, and F-measure, respectively, are obtained, which are significantly improved values when compared to other works.

In line fiber Mach–Zehnder inferometer (MZI) pulse compression was designed three different lengths of single mode-polarization maintaining fiber with (8, 16, 24) cm after splicing them between two single mode fibers (SMF-28e) with (23 and 13) cm and applying different weights on splicing region and the cross sectional area of SM-PM fiber, the designed performance of the in line fiber compressor system was studies in terms of compressor factor. Two minima pulse compression factor were obtained, one is 1.13 with FWHM 251.584 pm, centered wavelength 1547.394 nm, 52 cm interferometer length and 5 g was applied on the micro-cavity splicing region, and the second is equal 1.10 with FWHM 259.730 pm, centered wavelength 1547.120 pm and, 68 cm interferometer length and 10 g was applied on the cross sectional area of the second PMFs, in the case of single and cascaded interferometers, respectively. The input of the all interferometers was pulsed laser source with peak power 1.2297 mW, 286 pm spatial FWHM, 10 ns temporal FWHM, 3 kHz repetition rate and centered at 1546.7 nm.

In this work, we demonstrate a tunable optical frequency comb (OFC) source based on a cascaded frequency modulator (FM) and two Mach–Zehnder modulators (MZMs). The setup includes one FM and two MZMs, and a sinusoidal RF signal source that directly drive all these modulators. A Flat OFC source with a high number of comb lines, and tunable frequency spacing and center wavelength is analytically modelled and simulated. The results reveal that 51 comb lines with a frequency spacing of 25 GHz are generated when only FM is used. Thirteen of these lines have power variations of 1 dB. Next, by cascading FM with two MZMs, 127 comb lines are obtained. In addition, 101 of these lines have power variations of 1 dB. An optical frequency comb, with tunable frequency spacing ranging from 10 to 40 GHz is successfully generated. Moreover, the center wavelength of the generated OFC can be tuned from 1310 to 1610 nm.

To create a new transmission phenomenon, the availability of good data rates, the development of the internet of things (IoT), and different machine type communications (MTC) developed the ability to converse without synchronization, or the need for routing overhead in the form of synchronization overhead, while using mixed legacy fourth generation (4G) systems, based on orthogonal frequency division multiplexing, cannot meet these requirements (OFDM). Many waveform alternatives for OFDM have been proposed, including FBMC, GFDM, UFMC, and filtering-OFDM, in order to meet the criteria of the next generation system F-OFDM. As a consequence, a revolutionary filter based on a flat top weighted window is described in this work, where simulation results indicate that the suggested method outperforms prior designs in regard to spectral adeptness increased substantially acrros the deminish in the required side-information as overhead of the synchronization process. The trasitional F-OFDM uses root-raised-cosine filter. However, in this paper, novel filter design was proposed, whis is simple and real-time construction capability. This new filter is built around legacy filters, where the new filter is a combination of different filters to make use of various advantages of the old filters and get rid of the disadvangages. The power spectral density (PSD), -157.2 dBW/Hz, which is outstanding CP-OFDM-PSD, -50 dBW/Hz.

Optical frequency comb (OFC) sources, for their highly desirable properties, they have revolutionized a wide range of applications specifically orthogonal frequency-division multiplexing (OFDM) system. OFC sources based on femtosecond erbium fiber laser has emerged as the most commonly used in many applications owing to their advantages of low cost, robustness, compactness, high performance, and flexibility. Here, 300 fs soliton mode-locked pulses were achieved using erbium fiber oscillator based on an efficient Graphene saturable absorber and an external all-fiber pulse compressor consisted of erbium-doped fiber amplifier (EDFA) and 200 m long single-mode fiber (SMF). The proposed system works with a central wavelength of 1557 nm at the desirable communication band. The output power of the system and its corresponding pulse energy were 9.29 mW and 1.858 nJ, respectively, at a maximum pump power of 92.6 mW. The designed system is entirely fiber based, with no free-space optics and uses only standard telecommunication equipment. The results of this experiment demonstrate that the simple design of mode-locked fiber oscillator with an external compressor can provide a compact, portable, robust, reliable and high-performance femtoseconds frequency comb.

In this study, an optical frequency comb source (OFCS) based on a dual-drive Mach–Zehnder modulator (MZM) is constructed and theoretically demonstrated. A mathematical model of the constructed OFCS is then built to investigate the effect of the peak-to-peak radio frequency (RF) signals applied to the MZM arms on the generated optical frequency comb (OFC) lines at the MZM output. A dual-drive MZM, a continuous wave laser source, and an RF signal source are included in the OFCS. The chirp parameter can be controlled and 64 comb lines generated at a comb spacing of 25 GHz by regulating voltages applied to the MZM arms. The developed OFCS is relatively simple but valuable. The generated OFC lines can be used for high data-rate transmission.

A passively pulsed fiber laser using saturable absorbers such as graphene has been increased dramatically in recent years. Up to now, researchers have been proposed many methods to fabricate graphene saturable absorber such as (evanescent coupling structure, electrochemical exfoliation, and mechanical exfoliation) for light pulse generation in a fiber laser. However, each of these methods has got some limitations which reduce the saturable absorber performance and restrict its range of applications. In this paper, we propose a simple but very efficient fabrication way of graphene saturable absorber by converting graphene Nano powder into a thin film using polyvinyl alcohol (PVA) as a host material. The fabricated film can then be easily sandwiched between two fiber pigtails and inserted inside the laser cavity to form the saturable absorber. when compared with other methods, this method is much preferable because it provides saturable absorber with combat structure, maximum interaction area, reasonable insertion loss, polarization insensitive, controllable concentration, and safe to handle. The fabricated graphene saturable absorber in this paper was characterized and found to have a uniform distribution of the graphene nanomaterial in the PVA and have a modulation depth of 6.1% which make it a very promising saturable absorber for ultra-fast fiber laser demonstration.