啁啾管理调制格式中光谱整形滤波器优化

讨论了啁啾管理调制中光谱整形滤波器的作用及对直接调制激光器输出啁啾的影响,并对光谱整形滤波器种类、带宽、中心频率、阶数及滤波器在系统中的位置等进行了系统性的优化。结果表明优化后带宽为8.4 GHz、中心频率为193.1237 THz的1阶高斯型滤波器在滤波器前置无色散补偿啁啾管理光纤传输系统中性能最好,其1dB眼开度代价所对应的色散容限为5047 ps/nm。     

基于PolSK调制格式的FWM型全光比较器

文章提出了一种利用偏振移位键控(PolSK)信号光,基于半导体光放大器(SOA)中的四波混频(FWM)效应的超快全光比较器方案.该方案由于采用了功率恒定的PolSK信号光,可以消除SOA中的码型效应.通过数值模拟,研究了两输入信号光功率、SOA注入电流以及有源区长度对超快全光比较器输出特性的影响.     

基于OFDM调制和Nyquist滤波的超宽通道大容量光传输

文章首先概述了产生超宽通道的行业背景,接着介绍了产生超宽通道的两种主要方式;分别阐述了OFDM(正交频分复用)调制方式和Nyquist(奈奎斯特)滤波方式的基本原理和产生途径,分析了这两种方式的优劣特点并进行了比较;最后综述了两种方式的研究现状及今后展望。     

A simplified optical millimeter-wave generation scheme based on frequency-quadrupling

This paper analyzes and demonstrates a simplified frequency quadrupling configuration for optical millimeter-wave(mm-wave)generation,in which the electrical phase shifter and optical filter are omitted.Theoretical analysis is given to reach the optimum operating conditions including direct current(DC)bias voltage,optical transmission point of the dual-parallel Mach-Zehnder modulator(MZM)bias voltage,optical transmission point of the dual-parallel Mach-Zehnder modulator(DP-MZM),amplitude of the radio frequency(RF)driving signal and the impact of the extinction ratio(EF)on the optical sideband suppression ratio(OSSR)and radio frequency spurious suppression ratio(RFSSR).Experiments prove an OSSR of 15 dB and an RFSSR of 26 dB for the new frequency quadrupling scheme at 6 GHz,8 GHz and 10 GHz of RF driving signal without any electrical phase shifter or optical filter.This system exhibits the advantage of low wavelength dependence and large frequency tunable range.     

一种光通信系统中基于16-QAM的LDPC编码调制方案

设计了一种适用于16-QAM( quadrature amplitude modulation)系统的LDPC(low density parity check)级联编码调制方案。方案采 用了 本文所设计的一种低复杂度的软解调与二进制LDPC结合的算法,降低译码复杂度并增加方 案的实用性;同时方案 兼容当前OUT-4帧的级联码结构,这样可以利用级联码巧妙有效地解决LDPC码的错误平层问 题。仿真结果表明,本文 提出的LDPC级联编码调制方案,在误码率(BER)为10－8时,较G.709标准中的RS(255,9)的NCG(net code gain) 提高了2.8dB;同时,较ITU-T G.975.1标准 中两种码率相近的RS(255,9)+CSOC(n/k=7/6,J=8) 级联码和正交级联BCH码,在BER为10 －8时, 本文方案的NCG分别提高了1.3dB和0.2dB,且冗余度较两种方 案都低。此外,本文方案实现了3.28bits/symbol的SE (spectra l efficiency)。在BER为10－8时 ,本文方案较频谱效率低 于它的4-QAM、8-QAM以及8-QAM-RS(255,9)分别有着3.5、6.4和2dB的增益 。比较标准中建议的FEC(forward error correction)方案,本文提出的方案在NCG和SE两方面性能上都有所提升。     

Tunable modulation format conversion based on spectral line-by-line pulse shaper for all-optical signal processing

A tunable modulation format converter based on spectral line-by-line pulse shaper is proposed to realize different format conversions. The pulse shaper works as a format converter by setting its frequency response equivalent to the transform function between two formats. The working principles show that the format converter is suitable for different formats by adjusting its frequency response. Examples of format conversion from return to zero differential phase-shift keying （RZ-DPSK） to on-off keying （OOK） with different data packets and from return to zero （RZ） to non-return to zero （NRZ） are given. The results show that the format converter is not only suitable for different formats but also for random data packets.     

基于可编程光处理器的可调UWB信号产生方案

介绍了UWB信号产生的原理,提出了一种基于可编程光处理器(POP)的可调超宽带(UWB)信号产生方案,建立了完整的理论模型,并且对这种方案进行了仿真验证,实验结果表明该方案性能稳定,对偏振态、偏置电压漂移等问题都不敏感。     

Multi-level modulation scheme based on PAK algorithm for optical camera communications

In an optical camera communication (OCC) system, multi-level modulation is essential for data rate enhancement with the finite frame rate of the receiving camera constraint, where the K-means algorithm is widely used as a thresholding scheme. The result of K-means clustering is sensitive to initial cluster centers. In this paper, we propose a multi-level modulation scheme utilizing the pilot-aided K-means (PAK) algorithm. PAK algorithm innovates in both obtaining the state of the stripes propagated through the optical channel under different environments and overcoming the susceptibility of K-means. Our scheme could prompt data rate and improve the performance of OCC. Finally, non-orthogonal multiple access (NOMA) pattern is designed based on the proposed scheme to achieve multiplex communications.     

基于调制边带法的高次倍频光毫米波产生

提出了利用外调制技术的调制边带法的六倍频和八倍频光毫米波产生方案。方案仅采用一个马赫曾德尔调制器,并利用其非线性传输特性,通过调节MZM 的偏置电压和调制电压,控制边带的强度,仅保留三阶边带或四阶边带,从而实现六倍频及八倍频光毫米波的产生。采用将基带数据信号仅调制在一个三阶边带或四阶边带分量的方式,有效防止走离。数值分析结果表明,提出的方案仅需10 GHz 及7.5 GHz 的调制信号频率就能得到60 GHz 毫米波,大大减小了调制信号频率,增加了上变频系数,传输距离可达160 km,而功率代价变化不大。与提出的其他高倍频技术相比,由于系统仅采用一个马赫曾德尔调制器,提出的方案系统结构更为简单,且此方案色散影响较小,传输距离更长。     

一种改进的载波抑制调制光毫米波信号的产生方案

为了克服光纤无线(ROF)系统中色散对光载波抑制(OCS)调制光毫米波信号传输的影响,提出一种改进的OCS调制方案。使用双驱动马赫-曾德尔调制器(MZM),通过调整两路输入射频信号相位、基带信号增益和直流偏置电压将2.5Gbit/s数据信号仅调制到(OCS)信号的一个边带上传输。理论分析表明,与传统OCS调制光毫米波信号产生方案相比,本文方案解决了色度色散引起的码元走离问题,大大增加了传输距离。仿真实验结果表明,经过110km光纤传输后信号的眼图仍然十分清晰,在BER=10-10条件下,信号经过20、40和60km光纤传输后的功率代价分别为0.78、1.7和1.9dB。     

80-Gb/s wavelength conversion based on cross-phase modulation inhigh-nonlinearity dispersion-shifted fiber and optical filtering

Using cross-phase modulation in a 1-km high-nonlinearity dispersion-shifted fiber with subsequent filtering by a tunable optical filter, 80-Gb/s pulsewidth maintained wavelength conversion is realized. Penalty-free transmission over 80-km conventional single-mode fiber and 12-km dispersion-compensating fiber for 80-Gb/s converted signal is realized     

10-Gb/s external modulation in optical CPFSK format

We demonstrated a synchronous control technique for external optical modulation in a format of continuous-phase frequency-shift keying (CPFSK) at 10 Gb/s. In this method, the FSK signal in the upper- or lower-sideband state synchronously shifts to the other state at the timing when their phases are the same. We investigated the accuracy of the timing control required for the synchronous control. Experimental results show that the allowable timing misalignment to keep power penalty of the receiver sensitivity less than 1 dB was more than 25 ps, 25% of each bit period.     

一种基于D8PSK／ASK正交调制的新型光标记方案研究

深入研究了差分八相移键控（I）8PSK）j幅移键控（AsK）正交调制格式的机理,提出了一种基于D8PsKjASK正交调制的新型光标记方案,利用D8PSK作为载荷的调制方式,ASK作为标记的调制方式,仿真实现了载荷120Gb／s、标记10Gb／s的传输速率。分析了信号的消光比（ER）对误码率（BER）的影响,仿真结果表明...     

Block mapping spatial modulation scheme for MIMO systems

In this paper,a block mapping spatial modulation(BMSM)scheme is proposed to increase the transmit rate of multiple-input multiple-output(MIMO)wireless communication systems.In the BMSM scheme,the information to be transmitted is mapped into different combinations of transmit antenna indices and distinct constellation symbols at each time instant.Multiple transmit antennas are activated,which is different from spatial modulation(SM)and generalised spatial modulation(GSM)techniques,and also the information bi...     

A modulation scheme for 100 Gb/s modified minimum-shift keying format based on imbalanced bias in IQ components

We propose a modified minimum-shift keying (MSK) modulation scheme by applying the imbalanced bias on the in-phase and quadrature components of a MZM-based MSK modulator. This scheme enables constant envelope and continuous temporal phase shift of 100 Gb/s optical MSK signal by driving the MZMs with traditional sinusoidal signal instead of triangle signal. The principle of generating the optical MSK signal by this imbalanced scheme is presented. Theoretical analysis is given to modulated spectra, BER performance, residual dispersion tolerance and SPM tolerance. It is demonstrated that compared to the existing solutions the proposed scheme is able to decrease 2 dB receiver power penalty and improve SPM tolerance by 2 dB.     

Non-data-aided joint bit-rate and modulation format identification for next-generation heterogeneous optical networks

A novel and cost-effective technique for simultaneous bit-rate and modulation format identification (BR-MFI) in next-generation heterogeneous optical networks is proposed. This technique utilizes an artificial neural network (ANN) in conjunction with asynchronous delay-tap plots (ADTPs) to enable low-cost joint BR-MFI at the receivers as well as at the intermediate network nodes without requiring any prior information from the transmitters. The results of numerical simulations demonstrate successful identification of several commonly-used bit-rates and modulation formats with estimation accuracies in excess of 99.7%. The effectiveness of proposed technique under different channel conditions i.e. optical signal-to-noise ratio (OSNR) in the range of 14–28 dB, chromatic dispersion (CD) in the range of −500 to 500 ps/nm and differential group delay (DGD) in the range of 0–10 ps, is investigated and it has been shown that the proposed technique is robust against all these impairments.     

New modulation scheme based on elliptic functions

A new modulation scheme is proposed which modulates the signal shape. It is based on elliptic functions and retains two main features from amplitude and angular-modulation. Methods for modulation and demodulation are also given.     

Improved optical coding method for orthogonal ASK/DPSK modulation format

Orthogonal ASK/DPSK labeling, which encodes label information on optical carriers in a modulation format, is regarded as a competing scheme to subcarrier multiplexed optical labeling. However, the inherent cross-talk limits the extinction ratio (ER) of the payload and label sensitivity. In this paper, two optical coding methods-Manchester coding and 8B10B coding-which can remarkably improve the system quality to obtain acceptable ER are discussed. A novel optical packet encoding methodmark-insertion coding-is demonstrated to significantly reduce cross-talk between the amplitude shift keying ASK) payload and the differential phase shift keying (DPSK) label through spectrum shaping. The performance of mark-insertion coding depends on the number of inserted 'marks'. Finally, the transmission over a 40 km single mode fiber (SMF) is compared with optical label swapping for a. 40 Gbit/s ASK payload and 2.5 Gbit/s DPSK label under these coding schemes. The experimental result is consistent with the theoretical analysis.     

光纤通信系统中两种新型调制格式的比较

给出了光差分正交相移键控(DQPSK)和光八差分相移键控(8DPSK)调制格式的调制和解调方式,并用Matlab仿真得到了DQPSK和8DPSK调制的NRZ、RZ33和CSRZ系统的频谱图以及解调后的眼图.结果表明,DQPSK和8DPSK作为新型调制格式,具有更窄的频谱宽度、更高的频谱效率,经传输后的眼图性能也很好.