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[IEEE 2018 International Conference on Advanced Science and Engineering (ICOASE) - Duhok (2018.10.9-2018.10.11)] 2018 International Conference on Advanced Science and Engineering (ICOASE) - An ICI Reduction Based on PAPR Clipping in Coherent Optical OFDM System
摘要： The Inter-Carrier Interference (ICI) compensation for Coherent Optical Orthogonal Frequency Division Multiplexing (CO-OFDM) system has been studied in this paper. The purpose behind is to investigate the presence of ICI due to the impact of Laser Phase Noise (LPN) and Fiber Non-Linearity (FNL). Thereby, we propose a simple clipping scheme which represents an effective distortion algorithm to decrease the Peak to Average Power Ratio (PAPR) for 4QAM system. The method exhibits a significant process on ICI cancellation in CO-OFDM system. The OFDM signal is basically transmitted along 550km distance rated at 10Gbps single mode fiber for the coherent optical mode. The new findings show that the receiver sensitivity is highly improved below 10-3 FEC for laser power 5dBm; and archives about 1dBm to 2.4dBm when laser power becomes 8dBm at a typical clipping ratio of 0.6. In particular, the system exhibits a good performance over a 385km transmission distance in comparison to the conventional CO-OFDM. As a result, the proposed clipping shows that the system can enhance its the performance by reducing ICI in the CO-OFDM system; in addition to present a high robustness in BER metric against FNL by a clear reduction in PAPR.
关键词： Coherent Optical Orthogonal Frequency Division Multiplexing (CO-OFDM),Inter-Carrier Interference (ICI),Peak to Average Power Ratio (PAPR),Fiber Nonlinearity (FNL),Bit Error Rate (BER),Laser Phase Noise (LPN)
更新于2025-09-23 15:22:29
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OFDM tolerance to additive white Gaussian and laser phase noises in optical heterodyning systems accompanied by the feasible pilot-assisted equalization
摘要： It is well known that the performance of orthogonal frequency division multiplexing (OFDM) is limited by phase noise, which depends on the laser linewidths for coherent-detection radio over fiber (RoF) systems. In this manuscript, we present numerical and theoretical results to analyze the combined effects of phase and additive white Gaussian noises in the performance of RoF-OFDM schemes with the feasible pilot-based channel corrector. This phase-noise compensator is adopted due to its effectiveness as well as simplicity. It is shown that as the subcarrier modulation format increases, the required radio frequency linewidth for overcoming the FEC limit decreases by a factor of 10 times. Also, there is a signal–noise ratio penalty of 7 dB. Furthermore, it is demonstrated that the bit error rate enhances as the product of the laser linewidths and OFDM symbol period decreases because the pilot-assisted equalization method acts as a high-pass filter for phase noise. We finally discovered that the intermediate-frequency (IF) carrier suppression is not mandatory; the system performance is not affected by selecting properly the carrier–signal ratio and IF. To confirm the previous observation, a novel way to measure phase noise in RoF-OFDM signals accompanied by the IF carrier is proposed. The mean integral phase noise comes from the adaptation of the root mean square phase deviation of the single-carrier systems. This work serves as a guideline for the study and design of OFDM-based RoF schemes susceptible to direct and coherent detections.
关键词： Laser phase noise,Additive white Gaussian noise,Intermediate frequency suppression,Orthogonal frequency division multiplexing,Radio over fiber systems
更新于2025-09-19 17:13:59
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Compensation of Laser Phase Noise Based on Polar-Coordinates Decision
摘要： In this work, we proposed and experimentally demonstrated a phase-noise-mitigation scheme based on polar coordinates decision in the 16-QAM coherent optical communication system. The BER curves are measured to verify the feasibility of the scheme.
关键词： Polar coordinate,Decision,Laser phase noise
更新于2025-09-16 10:30:52
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Resolved-Sideband Cooling of a Levitated Nanoparticle in the Presence of Laser Phase Noise
摘要： We investigate the influence of laser phase noise heating on resolved sideband cooling in the context of cooling the center-of-mass motion of a levitated nanoparticle in a high-finesse cavity. Although phase noise heating is not a fundamental physical constraint, the regime where it becomes the main limitation in Levitodynamics has so far been unexplored and hence embodies from this point forward the main obstacle in reaching the motional ground state of levitated mesoscopic objects with resolved sideband cooling. We reach minimal center-of-mass temperatures comparable to Tmin ? 10 mK at a pressure of p ? 3 × 10?7 mbar, solely limited by phase noise. Finally we present possible strategies towards motional ground state cooling in the presence of phase noise.
关键词： levitated nanoparticle,laser phase noise,resolved sideband cooling,ground state cooling,optomechanical cooling
更新于2025-09-16 10:30:52
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Laser Phase Noise Tolerance of Uniform and Probabilistically-shaped QAM Signals for High Spectral Efficiency Systems
摘要： We numerically and experimentally investigate the laser phase noise tolerance of probabilistically shaped (PS) and uniformly shaped (US) quadrature amplitude modulation (QAM) signals. In the simulations, we compare PS-64QAM to US-16QAM, PS-256QAM to US-64QAM, and PS-1024QAM to US-256QAM under the same information rate (IR). We confirm that a sufficient shaping gain is observed with narrow linewidth lasers, whereas degradation of the shaping gain is clearly observed when large phase noise and high order modulation formats are assumed. We also evaluate the pilot ratio dependency of the required optical signal-to-noise ratio at the forward error correction limit and the achievable information rate. Additionally, we compare the performance of two types of CPR updating schemes: updating phase estimation at only the pilot symbol or at all symbols.
关键词： Digital coherent,high order quadrature amplitude modulation,laser phase noise,probabilistic shaping,optical fiber communication
更新于2025-09-16 10:30:52
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Assessment of the Combined Effect of Laser Phase Noise and Intercore Crosstalk on the Outage Probability of DD OOK Systems
摘要： We study the influence of the combined effect of laser phase noise and intercore crosstalk on the outage probability of direct-detection 10 Gbit/s on-off keying optical communication systems. We show that the laser phase noise can affect significantly the outage probability, for lasers with linewidths in the MHz range, for low and high skew-bit rate products. We also show that the laser phase noise effect on the received eye-pattern is qualitatively similar to the one found for high skew-bit rate product in the absence of laser phase noise.
关键词： intercore crosstalk,on-off keying,multicore fiber,laser phase noise,outage probability
更新于2025-09-12 10:27:22
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Phase Noise Characterization and EEPN of a Full C-band Tunable Laser in Coherent Optical Systems
摘要： We perform phase noise characterization of a tunable laser source that is capable of tuning to 103 channels between 1527.6-1568.36 nm with 50 GHz grid spacing between the channels. The measured frequency modulation (FM) noise power spectral density (PSD) is reproduced by simulations in order to investigate the impact of equalization-enhanced phase noise (EEPN) in a coherent transmission system. The simulations are performed on a 30 Gbaud channel with 16 quadrature amplitude modulation (16QAM) and using pilot-based carrier phase estimation with 3% overhead. By performing extensive system simulations, we show the impact of different accumulated dispersion. Furthermore, we show the possibility to overcome EEPN related penalties by using a local oscillator (LO) with reduced low frequency phase noise or flat FM-noise PSD profiles with lower linewidths.
关键词： Equalization-Enhanced Phase Noise,coherent systems,Laser Phase Noise,FM-noise power spectral density,Tunable Laser Source
更新于2025-09-11 14:15:04
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Precision locking CW laser to ultrastable optical frequency comb by feed-forward method
摘要： We locked a 1064 nm continuous wave (CW) laser to a Yb:fiber optical frequency comb stabilized to an ultrastable 972 nm CW laser with the feed-forward method. Consequently, the stability and coherent properties of the ultrastable laser are precisely transferred to the 1064 nm CW laser through the frequency comb’s connection. The relative linewidth of the frequency-stabilized 1064 nm CW laser is narrowed to 1.14 mHz, and the stability reaches 1.5 × 10?17/s at the optical wavelength of 1064 nm. The phase noise characterization in the 1 mHz–10 MHz range is presented to indicate that feed-forward locking a CW laser to an ultrastable comb will offer a potential technique for many important applications, such as optical frequency synthesis and gravitational wave detection.
关键词： feed-forward method,continuous wave laser,phase noise,frequency stability,optical frequency comb
更新于2025-09-11 14:15:04