- 标题
- 摘要
- 关键词
- 实验方案
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Coherent detection of ultraweak electromagnetic fields
摘要： We explore the application of heterodyne interferometry for a weak-field coherent detection scheme. The methods detailed here will be used in ALPS II, an experiment designed to search for weakly interacting, sub-eV particles. For ALPS II to reach its design sensitivity this detection system must be capable of accurately measuring fields with equivalent amplitudes on the order of 10?5 photons=s or greater. We present initial results of an equivalent dark count rate on the order of 10?5 photons=s as well as successful generation and detection of a signal with a field strength equivalent to 10?2 photons=s.
关键词： axionlike particles,heterodyne interferometry,ALPS II,weak-field detection,coherent detection
更新于2025-09-23 15:23:52
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Optical and Digital Key Enabling Techniques for SDM-Based Optical Networks
摘要： In order to support, in a cost-effective way, the data capacity demand in the context of future 5G networks, a new set of advanced technologies need to be explored, as it is the case of space-division multiplexing (SDM) along with energy efficient coherent detection based modulation formats. This paper presents the recent results on enabled optical networks based on SDM for high capacity optical networks compatible with 5G network infrastructure and data center connectivity. In particular, we demonstrate the viability of using Long-Period Gratings (LPGs) in multi-core fibers (MCFs) to develop different components for multicore-based SDM systems, such as pump couplers and core/wavelength selective multi-core switches and couplers. Moreover, we also present and characterize the performance of different digital signal processing (DSP) algorithms and subsystems supporting optical coherent detection in SDM systems.
关键词： Coherent detection,long period grating,generalized Stokes space,digital signal processing,space-division multiplexing,space-division demultiplexing
更新于2025-09-23 15:23:52
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Analytic and simulative comparison of turbulent FSO system with different modulation techniques
摘要： In this paper, we characterize the performance of Intensity Modulation/Direct Detection (IM/DD) and coherent detection modulation techniques in free-space optical (FSO) communication system in terms of bit error rate (BER). The system of interest includes M-ary Pulse Position Modulation (M-PPM) in correspondence to IM/DD and M-ary Phase Shift Keying (M-PSK) and M-ary Quadrature Amplitude Modulation (M-QAM) with respect to coherent detection. The system is subjected to weak turbulence regime of log-normal channel with scintillation index less than 0.75. Coherent techniques involve the amount of signal pulses transmitted in a particular time as the major component of their generation, except IM/DD which is a result of photon intensity, i.e. the number of photons forming a pulse. It is worth mentioning that in previous studies, the performance of IM/DD techniques had been evaluated in terms of photon-count fluctuation statistics and thus the impact of fading strength of channel on signal intensity was not discussed anywhere. In this work, an objective equivalence has been achieved between these two kinds of detection by deriving the BER expression of M-PPM in terms of probability density function of signal intensity, while considering fading strength, scintillation index, thermal noise and outage probability as system parameters for numerical analysis.
关键词： M-ary Pulse Position Modulation (MPPM),M-ary Phase Shift Keying (MPSK),M-ary Quadrature Amplitude Modulation (M-QAM),Intensity Modulation/Direct Detection (IM/DD),Scintillation index,Coherent detection
更新于2025-09-19 17:15:36
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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) - SDN-Enabled Adaptive Modulation and Coding in Hybrid C-RANs
摘要： In this invited paper, we describe our recently proposed software-defined networking (SDN)-enabled, adaptive resource allocation framework, including hybrid signalling schemes, for mobile fronthaul (MFH) networks that employ both coherent detection (CD) and direct detection (DD) technologies. To optimize application performance and network efficiency, we propose phase-coded three-level pulse amplitude modulation (PAM-3) for multicast traffic delivery to CD and DD nodes. We implement several connectivity scenarios based on both typical and improved PAM-3 in an SDN fronthaul testbed and examine the pre-forward error correction (FEC) bit error rate (BER) performance for 25 Gbaud signals. Using low-density parity-check (LDPC) codes to achieve the desired post-FEC BER levels, we study the performance gains due to code rate adaptation in dynamic wavelength-routing MFH networks.
关键词： coherent detection (CD),centralized radio access network (C-RAN),mobile fronthaul (MFH),software-defined networking (SDN),direct detection (DD),low-density parity-check (LDPC) coding
更新于2025-09-16 10:30:52
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[IEEE 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Sao Paulo, Brazil (2019.10.7-2019.10.9)] 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Comparative Study of 1-Tb/s Single Laser Coherent Optical Systems based on OFDM and Nyquist FDM
摘要： Two multiplexing techniques, digitally frequency multiplexed Nyquist FDM and OFDM, are evaluated in high-data rate coherent optical transmissions. Simulations are carried out to achieve a net data rate of 1 Tb/s through dual-polarization 64QAM and 256QAM at 100 GBd and 75 GBd, respectively. The systems’ performance were evaluated in terms of OSNR versus Tx and Rx laser linewidths, number of subcarriers, and DAC/ADC quantization and bandwidths. Despite similar performance for both techniques, CO-NFDM may allow a lower-cost implementation.
关键词： Metro,OFDM,Long-haul,coherent detection,digital signal processing,NFDM
更新于2025-09-16 10:30:52
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Performance enhancement of high-capacity coherent DWDM free-space optical communication link using digital signal processing
摘要： In this paper, 1.28 Tbps (32 × 40 Gbps) high-capacity DWDM-FSO link has been investigated for performance enhancement using coherent detection and digital signal processing (DSP). The DP-16QAM-modulated proposed DWDM-FSO link has been analyzed for both adverse weather and turbulent atmospheric conditions. It is observed that when link is subjected to strong turbulence along with adverse weather conditions, the DSP-aided coherent DWDM-FSO receiver achieves target bit error rate (BER) of 10?4 at signal-to-noise ratio (SNR) of 36.4 dB, while for similar conditions, the SNR requirements for IM/DD-based DWDM-FSO link shoots by 12.8 dB to 49.2 dB. Also, in terms of operational link range, the proposed link even under strong turbulent conditions serves 1.88 km, whereas IM/DD link was restricted to mere 1.12 km for target of BER of 10?4, thus producing a decent range increment of 760 m. The proposed link has been designed and investigated using OptiSystem? 14.2.
关键词： Atmospheric turbulence,Coherent detection,Digital signal processing,Free-space optical communication,Gamma–Gamma channel modeling,DWDM
更新于2025-09-16 10:30:52
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Advanced DSP for Coherent Optical Fiber Communication
摘要： In this paper, we provide an overview of recent progress on advanced digital signal processing (DSP) techniques for high-capacity long-haul coherent optical fiber transmission systems. Not only the linear impairments existing in optical transmission links need to be compensated, but also, the nonlinear impairments require proper algorithms for mitigation because they become major limiting factors for long-haul large-capacity optical transmission systems. Besides the time domain equalization (TDE), the frequency domain equalization (FDE) DSP also provides a similar performance, with a much-reduced computational complexity. Advanced DSP also plays an important role for the realization of space division multiplexing (SDM). SDM techniques have been developed recently to enhance the system capacity by at least one order of magnitude. Some impressive results have been reported and have outperformed the nonlinear Shannon limit of the single-mode fiber (SMF). SDM introduces the space dimension to the optical fiber communication. The few-mode fiber (FMF) and multi-core fiber (MCF) have been manufactured for novel multiplexing techniques such as mode-division multiplexing (MDM) and multi-core multiplexing (MCM). Each mode or core can be considered as an independent degree of freedom, but unfortunately, signals will suffer serious coupling during the propagation. Multi-input–multi-output (MIMO) DSP can equalize the signal coupling and makes SDM transmission feasible. The machine learning (ML) technique has attracted worldwide attention and has been explored for advanced DSP. In this paper, we firstly introduce the principle and scheme of coherent detection to explain why the DSP techniques can compensate for transmission impairments. Then corresponding technologies related to the DSP, such as nonlinearity compensation, FDE, SDM and ML will be discussed. Relevant techniques will be analyzed, and representational results and experimental verifications will be demonstrated. In the end, a brief conclusion and perspective will be provided.
关键词： coherent detection,neural network,space division multiplexing,digital signal processing,nonlinearity compensation,machine learning,optical fiber communication,equalization
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Optical Computing of Mathematical Derivatives using Dispersion and Coherent Detection
摘要： Early attempts in the field of optical computing were futile because they aimed to construct an all-optical equivalent of the digital computer [1]. However, photonics does have potential for performing certain computing functions in the analog domain [1]. These analog photonic hardware accelerators precede an optical-to-electrical conversion and alleviate bandwidth, dynamic range and power consumption bottlenecks on the subsequent electronics [2]. Far from a general purpose computer, photonic hardware accelerators are custom designed to perform specific signal transformations in real time and in analog domain. The computational operations that have already been realized by these analog optical computing primitives include integration [3], data compression [4], range compression [7]. Optical time~bandwidth implementation of temporal differentiation has been demonstrated in two ways: field differentiators realized using a micro-ring resonator [8] and intensity differentiators implemented using phase modulation [9]. Inspired by the physics of Photonic Time Stretch technology [10], and its spin-off in the form of the Phase Stretch Transform [11, 12] we propose a novel computational approach for calculating mathematical derivatives. The proposed all-optical differentiator consists of group delay dispersion primitives and coherent detection as shown in Figure 1. The re-configurability to compute different orders of differentiation is realized simply by controlling the applied group delay dispersion spectrum. The simulation results presented in Figure 2 demonstrate that the computation of any-order of differentiation of the input signal is possible. As shown in Figure 2, the imaginary component of the output gives the m-th order of differentiation while the real component of the output recovers the input signal. The proposed approach has promising applications in signal classification and is also easy to implement enabling realization of a real-time, low power and broad band optical differentiation functions.
关键词： photonic time stretch,coherent detection,phase stretch transform,optical computing,mathematical derivatives,dispersion
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - VCSEL Technologies for High-Capacity Dense WDM Networks
摘要： Long-wavelength vertical cavity surface emitting laser (VCSEL) technologies can represent an alternative solution for the development of transmitters with reduced cost, power consumption and footprint for very-high capacity metropolitan area systems. Exploiting direct modulation (DM) and advanced modulation formats, such as discrete multitone (DMT), and aggregating multiple DM-VCSELs emitting in the C-band with dense wavelength division multiplexers (WDM) in SOI chips allows to achieve multi-Tb/s transmitter module with 25 GHz granularity [1]. The interplay between the frequency chirp induced by VCSELs DM and the tight filtering of network WDM multiplexers plays a crucial role in the transmission performance. In this paper, we compare the adoption of two different long-wavelength InP VCSEL technologies: high-bandwidth short-cavity devices and MEMS-based widely-tuneable VCSELs [1]. We evaluate their performance in case of DM employing DMT modulation, providing more than 50-Gb/s capacity per wavelength; coherent detection (COH-D) is used to target hundreds of kilometres distances thanks to DSP chromatic dispersion (CD) compensation.
关键词： WDM,DMT,direct modulation,coherent detection,VCSEL
更新于2025-09-11 14:15:04
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Performance analysis of 349-element adaptive optics unit for a coherent free space optical communication system
摘要： As a continuation of our previous work [Optics Express.25, 15229(2017)] in which we have verified the performance of a coherent free space optical communication (FSOC) system with a 97-element adaptive optics (AO) system, in this paper, we evaluated the performance improvement of the coherent FSOC system using a large-scale high-speed AO system with a 349-element continuous surface deformable mirror. The mixing efficiency (ME) and bit-error-rate (BER) under different Greenwood frequency (GF) were calculated as the performance metric of coherent FSOC system. The performance of FSOC system using such a large-scale AO system was quantitatively verified for the first time. The obtained results showed that the performance was obviously improved when a larger-scale high-speed AO system is employed in coherent FSOC system. This analysis result provides a performance verification for large-scale high-speed AO systems used in FSOC system which is beneficial for coherent FSOC system parameters design.
关键词： bit-error-rate,adaptive optics,free space optical communication,coherent detection,mixing efficiency
更新于2025-09-11 14:15:04