scholarly journals Optical Transmitters without Driver Amplifiers—Optimal Operation Conditions

2018 ◽  
Vol 8 (9) ◽  
pp. 1652 ◽  
Author(s):  
Arne Josten ◽  
Benedikt Baeuerle ◽  
Romain Bonjour ◽  
Wolfgang Heni ◽  
Juerg Leuthold
Keyword(s):  
Single Channel ◽  
Direct Detection ◽  
Signal To Noise Ratio ◽  
Optical Signal ◽  
Optimal Operation ◽  
Signal Quality ◽  
Root Mean Square Amplitude ◽  
Operation Conditions ◽  
Communication Links ◽  
Eye Opening

An important challenge in optical communications is the generation of highest-quality waveforms with a Mach–Zehnder modulator with a limited electrical swing (Vpp). For this, we discuss, under limited Vpp, the influence of the waveform design on the root-mean-square amplitude, and thus, the optical signal quality. We discuss the influence of the pulse shape, clipping, and digital pre-distortion on the signal quality after the electrical-to-optical conversion. Our simulations and experiments, e.g., suggest that pre-distortion comes at the expense of electrical swing of the eye-opening and results in a lower optical signal-to-noise ratio (OSNR). Conversely, digital post-distortion provides operation with larger eye-openings, and therefore, provides an SNR increase of at least 0.5 dB. Furthermore, we find that increasing the roll-off factor increases the electrical swing of the eye-opening. However, there is negligible benefit of increasing the roll-off factor of square-root-raised-cosine pulse shaped signals beyond 0.4. The findings are of interest for single-channel intensity modulation and direct detection (IM/DD) links, as well as optical coherent communication links.

40 Gb/s High-speed mode-division multiplexing transmission employing NRZ modulation format

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Rabiu Imam Sabitu ◽  
Nafizah Goriman Khan ◽  
Amin Malekmohammadi
Keyword(s):  
System Performance ◽  
High Speed ◽  
Direct Detection ◽  
Signal To Noise Ratio ◽  
Optical Signal ◽  
Threshold Power ◽  
Modulation Format ◽  
Transmission Distance ◽  
Mode Division Multiplexing ◽  
Speed Mode

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.

scholarly journals In-Band OSNR Measurement Method for All-Optical Regenerators in Optical Domain

2019 ◽  
Vol 9 (24) ◽  
pp. 5438
Author(s):  
Feng Wan ◽  
Baojian Wu ◽  
Feng Wen ◽  
Kun Qiu
Keyword(s):  
Measurement Method ◽  
Signal To Noise Ratio ◽  
Optical Signal ◽  
Error Vector Magnitude ◽  
Regeneration System ◽  
Data Rates ◽  
All Optical ◽  
Communication Links ◽  
Shift Keying ◽  
Nonlinear Devices

We propose an in-band measurement method of optical signal-to-noise ratio (OSNR) output from an all-optical regeneration system with a nonlinear power transfer function (PTF) according to the fact that there are different average gains of signal and noise. For the all-optical quadrature phase-shift keying (QPSK) regenerator as an example, the output OSNR is derived from the input OSNR and the total gain of the degraded QPSK signal. Our simulation shows that the OSNR results obtained by this method are in agreement with those calculated from the error vector magnitude (EVM) formula. The method presented here has good applicability for different data rates but is also useful for analyzing the OSNR degradation of other nonlinear devices in optical communication links.

Efficient Blind Adaptive CSE to Reduce Cyclic Prefix Length in Direct Detection Optical OFDM Systems

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Asmaa Benieddi ◽  
Sid Ahmed Elahmar
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Group Velocity Dispersion ◽  
Signal To Noise Ratio ◽  
Single Mode ◽  
Optical Signal ◽  
Single Mode Fiber ◽  
Cyclic Prefix ◽  
Ofdm Systems ◽  
Blind Adaptive

AbstractDirect detection optical orthogonal frequency division multiplexing (DDO-OFDM) systems for a long-reach of standard single mode fiber (SSMF) require a large length of cyclic prefix (CP) to avoid the inter-symbol interference (ISI) effect caused by group velocity dispersion (GVD). Unfortunately, this method is inefficient due to the energy wasted in CP samples. In order to reduce the CP length and to mitigate the residual ISI, a novel blind adaptive channel shortening equalizer (CSE) is proposed in this paper. Based on the orthogonality between subcarriers in the fast Fourier transform (FFT) property, the proposed algorithm attempts to minimize the sum-squared correlation (SSCM) between each sample located in a well-defined window to update the CSE coefficients. Thus, the combined channel-CSE response is shortened. Therefore, it can cancel the residual ISI effect due to the GVD and the short CP length. The performance of the system is evaluated on basis of bit error rate (BER) versus optical signal to noise ratio (OSNR) for different CP lengths. The simulation results validate the new algorithm SSCM and show that it can reduce the CP length with a much better system improvement than existing algorithms.

All-Optical XOR Logic Gates: Insights and Comparisons

2015 ◽  
Vol 815 ◽  
pp. 353-358 ◽  
Author(s):  
Mohd Azarulsani Md Azidin ◽  
M.H.A. Wahid ◽  
N.A.M. Ahmad Hambali ◽  
M.M. Shahimin ◽  
A. Zakiah Malek
Keyword(s):  
Phase Modulation ◽  
Signal To Noise Ratio ◽  
Logic Gate ◽  
Extinction Ratio ◽  
Logic Gates ◽  
Optical Amplifier ◽  
Optical Signal ◽  
Signal Quality ◽  
Gain Modulation ◽  
All Optical

Three XOR photonics logic gate configurations namely semiconductor optical amplifier-Mach Zender interferometer cross phase modulation (SOA-MZI XPM), SOA-MZI cross gain modulation (XGM) and terahertz optical asymmetrical demultiplexer (TOAD) XOR are analysed and compared in terms of generated power, optical signal-to-noise ratio (OSNR) values and bit error rate (BER) signal quality. The highest generated power is possessed by the TOAD at 23.5 dBm, the SOA-MZI XPM showed the most extinction ratio or OSNR with 109.6 dB whereas the best BER is recorded in the SOA-MZI XGM at 4.42 x 10-22.

A Study of Clustering for the Enhancement of Image Resolution in Dynamic Photon Emission

2019 ◽  
Author(s):  
S. Chef ◽  
C. T. Chua ◽  
C. L. Gan
Keyword(s):  
Signal To Noise Ratio ◽  
Photon Emission ◽  
Optical Signal ◽  
Image Resolution ◽  
Time Dimension ◽  
Processing Scheme ◽  
3D Space ◽  
Initial Acquisition ◽  
Resolution Limits ◽  
Emission Microscopy

Abstract Limited spatial resolution and low signal to noise ratio are some of the main challenges in optical signal observation, especially for photon emission microscopy. As dynamic emission signals are generated in a 3D space, the use of the time dimension in addition to space enables a better localization of switching events. It can actually be used to infer information with a precision above the resolution limits of the acquired signals. Taking advantage of this property, we report on a post-acquisition processing scheme to generate emission images with a better image resolution than the initial acquisition.

Comparative analysis of SISO and wavelength diversity-based FSO systems at different transmitter power levels

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Varun Srivastava ◽  
Abhilash Mandloi ◽  
Dhiraj Kumar Patel
Keyword(s):  
Optical Signal ◽  
Free Space Optical ◽  
Optical Source ◽  
Transmit Power ◽  
Single Input Single Output ◽  
Transmitter Power ◽  
Single Output ◽  
Communication Links ◽  
Single Input ◽  
Matching Performance

AbstractFree space optical (FSO) communication refers to a line of sight technology, which comprises optical source and detector to create a link without the use of physical connections. Similar to other wireless communication links, these are severely affected by losses that emerged due to atmospheric turbulence and lead to deteriorated intensity of the optical signal at the receiver. This impairment can be compensated easily by enhancing the transmitter power. However, increasing the transmitter power has some limitations as per radiation regulations. The requirement of high transmit power can be reduced by employing diversity methods. This paper presents, a wavelength-based diversity method with equal gain combining receiver, an effective technique to provide matching performance to single input single output at a comparatively low transmit power.

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