Combined Effect of ASE Noise and SRS Induced Crosstalk on the BER Performance of a Single Span WDM System with Raman Amplifier Using Heterodyne Coherent Detection

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
F.H. Tithi ◽  
S.P. Majumder

AbstractAnalysis is presented to evaluate numerically the combined effect of amplified spontaneous emission (ASE) and stimulated Raman scattering (SRS) on the bit error rate performance of a WDM transmission system with Raman amplifier using heterodyne receiver. The results are compared with those for a WDM system reported with direct detection receiver for different system parameters. It is observed that coherent heterodyne system is less affected by the crosstalk due to combined effect of ASE and SRS compared to direct detection. It is noticed that allowable transmission distance is 170 km, and 166 km of WDM channels for 8, and 16, respectively, when coherent heterodyne receiver is and with pump power of 10 mW and channel bandwidth of 12.5 GHz. The corresponding transmission distance is 60 km and 10 km, respectively, for direct detection system already reported.

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Sunil Kumar Dahiya ◽  
Amit Kumar Garg

AbstractOptical transmission impairments are most critical reason to reduce both capacity and achievable transmission distance in optical communication system. Advanced modulation formats are important keys to reduce optical transmission impairments in digital signal processing (DSP) based coherent wavelength division multiplexed (WDM) system. These formats are more robust to non-linearity of optical fiber and results in increasing both spectral efficiency and bandwidth. Coherent detection technique increases sensitivity of receiver up to 30 dB in comparison of direct detection. Simulink seems to be the best cost-effective platform for analyzing mathematical modeling of optical coherent system. In this paper, mathematical model has been developed to analyze the optical transmission impairments by employing the advanced polarization multiplexed QPSK modulation in DSP based WDM coherent system. The simulation results have shown bit error rate (BER) improvement up to 10−6 and enhanced transmission distance to 150 km. These values have seen to be in close proximity with experimental results. The developed mathematical model seems to be more useful for extending the existing WDM optical system for longer distances with acceptable BER.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yousuke Nishida ◽  
Naoki Nishigami ◽  
Sebastian Diebold ◽  
Jaeyoung Kim ◽  
Masayuki Fujita ◽  
...  

AbstractTowards exploring advanced applications of terahertz (THz) electromagnetic waves, great efforts are being applied to develop a compact and sensitive THz receiver. Here, we propose a simple coherent detection system using a single resonant tunnelling diode (RTD) oscillator through self-oscillating mixing with an RTD oscillator injection-locked by a carrier wave. Coherent detection is successfully demonstrated with an enhancement in the sensitivity of >20 dB compared to that of direct detection. As a proof of concept, we performed THz wireless communications using an RTD coherent receiver and transmitter. We achieved 30-Gbit/s real-time error-free transmission, which is the highest among all electronic systems without error correction to date. Our results show that the proposed system can reduce the size and power consumption of various THz systems including sensing, imaging and ranging, which would enable progress to be made in a wide range of fields in such as material science, medicine, chemistry, biology, physics, astronomy, security, robotics and motor vehicle.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Rabiu Imam Sabitu ◽  
Nafizah Goriman Khan ◽  
Amin Malekmohammadi

AbstractThis report examines the performance of a high-speed MDM transmission system supporting four nondegenerate spatial modes at 10 Gb/s. The analysis adopts the NRZ modulation format to evaluate the system performance in terms of a minimum power required (PN) and the nonlinear threshold power (PTH) at a BER of 10−9. The receiver sensitivity, optical signal-to-noise ratio, and the maximum transmission distance were investigated using the direct detection by employing a multimode erbium-doped amplifier (MM-EDFA). It was found that by properly optimizing the MM-EDFA, the system performance can significantly be improved.


Photonics ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 38
Author(s):  
Moshe Nazarathy ◽  
Ioannis Tomkos

In optical transmitters generating multi-level constellations, optical modulators are preceded by Electronic Digital-to-Analog-Converters (eDAC). It is advantageous to use eDAC-free Optical Analog to Digital Converters (oDAC) to directly convert digital bitstreams into multilevel PAM/QAM optical signals. State-of-the-art oDACs are based on Segmented Mach-Zehnder-Modulators (SEMZM) using multiple modulation segments strung along the MZM waveguides to serially accumulate binary-modulated optical phases. Here we aim to assess performance limits of the Serial oDACs (SEMZM) and introduce an alternative improved Multi-Parallel oDAC (MPoDAC) architecture, in particular based on arraying multiple binary-driven MZMs in parallel: Multi-parallel MZM (MPMZM) oDAC. We develop generic methodologies of oDAC specification and optimization encompassing both SEMZM and MPMZM options in Direct-Detection (DD) and Coherent-Detection (COH) implementations. We quantify and compare intrinsic performance limits of the various serial/parallel DD/COH subclasses for general constellation orders, comparing with the scant prior-work on the multi-parallel option. A key finding: COH-MPMZM is the only class synthesizing ‘perfect’ (equi-spaced max-full-scale) constellations while maximizing energy-efficiency-SEMZM/MPMZM for DD are less accurate when maximal energy-efficiency is required. In particular, we introduce multiple variants of PAM4|8 DD and QAM16|64 COH MPMZMs, working out their accuracy vs. energy-efficiency-and-complexity tradeoffs, establishing their format-reconfigurability (format-flexible switching of constellation order and/or DD/COH).


2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yibeltal Chanie Manie ◽  
Run-Kai Shiu ◽  
Peng-Chun Peng ◽  
Bao-Yi Guo ◽  
Mekuanint Agegnehu Bitew ◽  
...  

A fiber Bragg grating (FBG) sensor is a favorable sensor in measuring strain, pressure, vibration, and temperature in different applications, such as in smart structures, wind turbines, aerospace, industry, military, medical centers, and civil engineering. FBG sensors have the following advantages: immune to electromagnetic interference, light weight, small size, flexible, stretchable, highly accurate, longer stability, and capable in measuring ultra-high-speed events. In this paper, we propose and demonstrate an intensity and wavelength division multiplexing (IWDM) FBG sensor system using a Raman amplifier and extreme learning machine (ELM). We use an IWDM technique to increase the number of FBG sensors. As the number of FBG sensors increases and the spectra of two or more FBGs are overlapped, a conventional peak detection (CPD) method is unappropriate to detect the central Bragg wavelength of each FBG sensor. To solve this problem, we use ELM techniques. An ELM is used to accurately detect the central Bragg wavelength of each FBG sensor even when the spectra of FBGs are partially or fully overlapped. Moreover, a Raman amplifier is added to a fiber span to generate a gain medium within the transmission fiber, which amplifies the signal and compensates for the signal losses. The transmission distance and the sensing signal quality increase when the Raman pump power increases. The experimental results revealed that a Raman amplifier compensates for the signal losses and provides a stable sensing output even beyond a 45 km transmission distance. We achieve a remote sensing of strain measurement using a 45 km single-mode fiber (SMF). Furthermore, the well-trained ELM wavelength detection methods accurately detect the central Bragg wavelengths of FBG sensors when the two FBG spectra are fully overlapped.


2013 ◽  
Vol 52 (22) ◽  
pp. 7282-7288 ◽  
Author(s):  
Wan-Joong Kim ◽  
Sanghee Kim ◽  
Ae Rhan Kim ◽  
Dong Jin Yoo

Author(s):  
Victor Parusov ◽  
Boris Ovchinnikov

Gas electron multipliers (GEMs) with wire (WGEMs) or metal electrodes (MGEMs), which don’t use any plastic insulators between electrodes are created. The chambers containing MGEMs (WGEMs) with pin-anodes are proposed as detectors for searching of spin-dependent interactions between Dark Matter (DM) particles and gases with nonzero-spin nuclei (H2, D2, 3He, 21Ne, CF4, CH4, etc.). In this paper, we present a review of such chambers. For investigation of the gas mixtures Ne+10%H2, H2 (D2) +3ppmTMAE, the chamber containing WGEM with pin-anode detection system was constructed. In this paper we present the results of an experimental study of these gaseous mixtures exited by an α - source. Mixture of Ar + 40 ppm C2H4 and mixture 50% Xe + 50%CF4 have been investigated. The spatial distributions of photoelectron clouds produced by primary scintillations on α- and β-particle tracks, as well as the distributions of photoelectron clouds due to photons from avalanches at the pin-anode, have been measured for the first time. In our experiments as another filling of the chambers for search of low-mas WIMP (<10 GeV/c2), solar neutrino and solar axions with spin-dependent interaction we propose to use the mixtures: D2 + 3ppmTMAE, 3He + 3%CH4, 21Ne + 10%H2, at pressure 10-17 bar. And in our experiment with liquid gases is used the mixtures with 19F (LAr + CF4, LXe + CF4) and mixture LCH4 + 40ppm TMAE. The time projection chamber (TPC) with the mixture D2 + 3ppmTMAE filling allow to search of spin-dependent interactions of solar axions and deuterium. As well as we present the detecting systems for search of narrow pp-resonances (quarks) in accelerators experiments.


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