optical signal
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Author(s):  
Yazan Alkhlefat ◽  
Sevia Mahdaliza Idrus Sutan Nameh ◽  
Farabi M. Iqbal

Current and future wireless communication systems are designed to achieve the user’s demands such as high data rate and high speed with low latency and simultaneously to save bandwidth and spectrum. In 5G and 6G networks, a high speed of transmitting and switching is required for internet of things (IoT) applications with higher capacity. To achieve these requirements a semiconductor optical amplifier (SOA) is considered as a wavelength converter to transmit a signal with an orthogonal frequency division multiplexing with subcarrier power modulation (OFDM-SPM). It exploits the subcarrier’s power in conventional OFDM block in order to send additional bits beside the normally transmitted bits. In this paper, we optimized the SOA’s parameters to have efficient wavelength conversion process. These parameters are included the injection current (IC) of SOA, power of pump and probe signals. A 7 Gbps OFDM-SPM signal with a millimeter waves (MMW) carrier of 80 GHz is considered for signal switching. The simulation results investigated and analyzed the performance of the designed system in terms of error vector magnitude (EVM), bit error rate (BER) and optical signal-to-noise ratio (OSNR). The optimum value of IC is 0.6 A while probe power is 9.45 and 8.9 dBm for pump power. The simulation is executed by virtual photonic integrated (VPI) software.


Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 609
Author(s):  
Roman Meshcheryakov ◽  
Andrey Iskhakov ◽  
Mark Mamchenko ◽  
Maria Romanova ◽  
Saygid Uvaysov ◽  
...  

The paper proposes an approach to assessing the allowed signal-to-noise ratio (SNR) for light detection and ranging (LiDAR) of unmanned autonomous vehicles based on the predetermined probability of false alarms under various intentional and unintentional influencing factors. The focus of this study is on the relevant issue of the safe use of LiDAR data and measurement systems within the “smart city” infrastructure. The research team analyzed and systematized various external impacts on the LiDAR systems, as well as the state-of-the-art approaches to improving their security and resilience. It has been established that the current works on the analysis of external influences on the LiDARs and methods for their mitigation focus mainly on physical (hardware) approaches (proposing most often other types of modulation and optical signal frequencies), and less often software approaches, through the use of additional anomaly detection techniques and data integrity verification systems, as well as improving the efficiency of data filtering in the cloud point. In addition, the sources analyzed in this paper do not offer methodological support for the design of the LiDAR in the very early stages of their creation, taking into account a priori assessment of the allowed SNR threshold and probability of detecting a reflected pulse and the requirements to minimize the probability of “missing” an object when scanning with no a priori assessments of the detection probability characteristics of the LiDAR. The authors propose a synthetic approach as a mathematical tool for designing a resilient LiDAR system. The approach is based on the physics of infrared radiation, the Bayesian theory, and the Neyman–Pearson criterion. It features the use of a predetermined threshold for false alarms, the probability of interference in the analytics, and the characteristics of the LiDAR’s receivers. The result is the analytical solution to the problem of calculating the allowed SNR while stabilizing the level of “false alarms” in terms of background noise caused by a given type of interference. The work presents modelling results for the “false alarm” probability values depending on the selected optimality criterion. The efficiency of the proposed approach has been proven by the simulation results of the received optical power of the LiDAR’s signal based on the calculated SNR threshold and noise values.


Author(s):  
Aayush Kumar Jaiswal ◽  
Ari Hokkanen ◽  
Markku Kapulainen ◽  
Alexey Khakalo ◽  
Nonappa ◽  
...  

Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 90
Author(s):  
Yuhang Hu ◽  
Zihao Yang ◽  
Nuo Chen ◽  
Hanwen Hu ◽  
Bowen Zhang ◽  
...  

Information capacity of single-mode fiber communication systems face fundamental limitations imposed by optical nonlinearities. Spatial division multiplexing (SDM) offers a new dimension for upgrading fiber communication systems. Many enabling integrated devices, such as mode multiplexers and multimode bending with low crosstalk, have been developed. On the other hand, all-optical signal processing (AOSP) can avoid optical to electrical to optical (O–E–O) conversion, which may potentially allow for a low cost and green operation for large-scale signal processing applications. In this paper, we show that the system performance of AOSP can be pushed further by benefiting from the existing technologies developed in spatial mode multiplexing (SDM). By identifying key technologies to balance the impacts from mode-dependent loss, crosstalk and nonlinearities, three-channel 40 Gbit/s optical logic operations are demonstrated using the first three spatial modes in a single multimode waveguide. The fabricated device has a broadband four-wave mixing operation bandwidth (>20 nm) as well as high conversion efficiency (>−20 dB) for all spatial modes, showing the potential for a large-scale signal processing capacity with the combination of wavelength division multiplexing (WDM) and SDM in the future.


2022 ◽  
Author(s):  
Yi-Chi Chen ◽  
Chien-Hung Yeh ◽  
Wen-Piao Lin ◽  
Li-Hung Liu ◽  
Han-Shin Ko ◽  
...  

Abstract In this paper, an erbium-doped fiber (EDF) laser with symmetric Sagnac dual-ring scheme is experimentally studied to achieve tunable and stable continuous-wave (CW) single-longitudinal-mode (SLM) presentation. In the measurement, the obtained wavelength-tuning bandwidth can be reached from 1518.0 to 1578.0 nm based on a C-band EDF gain-medium. Moreover, the corresponding output power, optical signal to noise ratio (OSNR) and wavelength linewidth of the designed EDF laser are studied and performed simultaneously.


Author(s):  
Md Anowar Hossain

Chromatic and achromatic (AC) assessments of camouflage textiles have been critical to the defense researchers for concealment, detection, recognition, and identification (CDRI) of target signature against multidimensional combat background (CB). AC assessment and camouflage measurement techniques are simulated and experimented for assessment of camouflage textiles against CB. This model has been demonstrated for color measurement spectrophotometer, scanning electron microscopy (SEM), digital imaging, hyperspectral imaging, and image processing software (ImageJ) for the advancement and establishment of AC camouflage textiles assessment. The chromatic variations of 48 artificial target objects (TOBs) have been synthesized by image processing; the technique can be implemented for defense CB-CDRI assessment. Microstructural variation versus optical signal of woodland, desertland and stoneland CB materials have been elucidated by SEM magnification. The achromatic variation of CB materials have been demonstrated for the replacement of optical signal against modern remote sensing device to the imaging sensor. Color difference (Δ E), microstructural variations, pixel variations to imaging signal and standard deviation of CB materials have been represented for remote sensing surveillance of defense applications against TOB-CB-CDRI. Technical simulation of color, texture, gloss, and pixel intensity has been derived for AC-CDRI assessment of camouflage textiles in TOBs-CB environment.


2022 ◽  
Author(s):  
Shayan Mookherjee

Multi-microresonator photonic circuits can improve the conversion efficiency of nonlinear optics, realize higher-order, implement programmable filters, and other advances in optical signal processing. However, such structures are challenging to realize in practice. Through a deeper understanding of disorder effects in photonics, we have greatly advanced the state-of-the-art in CROW structures and their applications in linear, nonlinear and quantum optics.


2021 ◽  
Author(s):  
Jayashree Pradhan ◽  
Pratiksha Holey ◽  
Vinod Kiran Kappala ◽  
Santos Kumar Das

Abstract Visible light communication (VLC) is seeking a lot of attention in the recent years due to high bandwidth, low cost, ease of implementation. VLC can be used for illumination as well as communication at the same time. Light emitting diode (LED) acts as a transmitter for data transmission and photo detector is used at the receiver side. Intensity Modulation (IM) is used to convert electrical signal into optical signal where only real and positive signal need to be transmitted. Optical orthogonal frequency division multiplexing (O-OFDM) is used in the VLC to enhance the bandwidth limitation due to LED. Using OOFDM for VLC does not provide the massive connectivity in an multi-user environment. A Non orthogonal multiple access (NOMA) is the further expansion where user can use both the time and frequency resources but distinguished in power domain with successive interference cancellation (SIC) at the receiver to decode the signal of each user. Also, Asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) is used to get positive signal with enhanced spectral efficiency. The proposed method is evaluated analytically and using simulation in terms of bit error rate (BER).


2021 ◽  
Vol 7 (4) ◽  
pp. 18-30
Author(s):  
A. Bourdine ◽  
S. Pashin

This article presents results of approbation of developed model of piece-wise regular fiber optic link, operating in a few-mode regime, with series-connected couple of special multimode optical crypto-fibers “encryptor-decoder”. Unlike the previously developed solution, the model was modified with an ability to take into account influence of fiber optic connector end-face contamination on laser-excited optical signal launching conditions. We present comparison results of computed optical pulse response envelops, distorted during propagation over 10GBase-LX network fiber optic links, containing optical crypto-fibers, depending on various conditions of transceiver laser source connector ferrule end-face contamination.


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