Investigation on the combined orthogonal FSK/ASK labeled signal based on cross gain modulation in a SOA

An optical frequency shift keying(FSK) transmitter performed by the cross gain modulation(XGM) in a semiconductor optical amplifier(SOA) is used in an optical label switching(OLS) system with 622 Mbit/s FSK label and 10 Gbit/s amplitude shift keying(ASK) payload.The key parameters in this system are optimized to achieve the best performance of FSK/ASK signal,including the input power of LD,the extinction ratio(ER) of the control light and that of the ASK payload.Besides,the transmission performance of ASK p...     

多种调制格式微波信号的光学产生方案

提出了一种基于偏振调制器（PolM）和Sagnac环级联的多调制格式微波信号的光学产生方案。理论分析了PolM在基带编码信号的驱动下产生偏振键控（PolSK）信号的基本原理,Sagnac环中嵌有两个马赫增德尔调制器（MZM）,分别对顺时针和逆时针传输的PolSK信号进行独立调制。通过合理调整两个MZM的驱动信号,实现了幅移键控（ASK）、频移键控（FSK）和相移键控（PSK）微波信号的产生。在仿真实验中,产生了比特率为2 Gbit/s的40 GHz ASK信号、20/40 GHz FSK信号和20 GHz PSK信号,同时验证了比特率和载波频率的宽带可调谐性。Sagnac环结构提升了系统的稳定性,并且针对每种调制格式的微波信号,在不改变链路结构的情况下其比特率和载波频率都可以通过控制基带编码信号和MZM的射频驱动来进行独立且灵活的调谐。     

ASK／FSK光标记交换系统中的OBPF谱均衡法

基于幅移键控／频移键控（ASK／FSK）正交调制光标记交换（0LS）系统工作原理,提出了一种利用光带通滤波器（OBPF）对FSK标记进行谱均衡的方法,从而有效改善ASK净荷接收灵敏度。利用仿真,对40Gb／sASK／FSK正交调制OLS系统,在使用3种不同类型OBPF进行谱均衡时的传输性能进行了验证与比较分析。结果表明...     

Joint Maximum Likelihood Sequence Estimation for Chromatic-Dispersion Compensation in ASK-DPSK Modulation Format

We determine the fundamental impairment mechanism in the chromatic-dispersion (CD)-limited hybrid amplitude shift keying (ASK)-differential phase-shift keying (DPSK) modulation format and propose the employment of joint maximum likelihood sequence estimation (J-MLSE) for CD compensation to extend the transmission reach of such format. We find that it is not the intrasubchannel interference of the ASK or DPSK subchannel but the interaction between these two subchannels that limits the transmission distance. Therefore, electronic equalization of the two subchannels separately cannot improve the overall CD tolerance of the ASK-DPSK signal. J-MLSE, however, exploits the correlation information between the detected ASK and DPSK signals and is numerically shown to improve the CD tolerance of the ASK-DPSK signal significantly     

Dispersion-tolerant transmission using a duobinarypolarization-shift keying transmission scheme

We demonstrate a novel dispersion-tolerant transmission scheme based on a three-level duobinary-encoded polarization-shift keying (PoISK) transmission format. Simulations over standard single-mode fiber demonstrate an improvement in the chromatic dispersion-limited transmission distance from ~65 km, using conventional nonreturn to zero intensity modulation to ~195 km for duobinary PoISK     

一种简单多径信道下的调制识别方法

为解决简单多径条件下调制识别类型少、难以工作于低信噪比下的问题,提出了一种基于联合特征参数的调制识别方法。根据简单多径下不考虑多普勒效应影响这一条件,利用调制信号的延迟相关和瞬时自相关特性,并结合高阶累积量特征对幅移键控(ASK)、相移键控(PSK)、频移键控(FSK)共8种信号进行分类识别。仿真结果表明,在信噪比大于4 dB时,简单多径条件下的各类调制信号正确识别率接近100%。     

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...     

All-optical modulation format conversion from PSK to ASK based on phase-sensitive amplification

With the development of the optics communication system and optical signal modulation technology, the amplitude-shift keying (ASK) and phase-shift keying (PSK) are both used in different optical communication sub-networks. In this paper, a novel all-optical modulation format from PSK to ASK based on phase-sensitive amplification is proposed and demonstrated. Using the nonlinear interference of the single-pump phase-sensitive amplification, the signal wavelength can be preserved while the modulation format is conversed. The proposed scheme provides the flexible intermediate node interface transformation in future optical networks.     

M-ary amplitude shift keying OFDM system

Coherent M-ary amplitude-shift keying (MASK) is proposed for use in orthogonal frequency-division multiplexing (OFDM) systems. The frequency separation between subcarriers is only 1/2T instead of 1/T. With a slightly wider bandwidth, an /spl radic/M-ary ASK OFDM can achieve the same bit-error rate (BER) of M-ary quadrature amplitude modulation (QAM) OFDM and a better BER than that of M-ary phase-shift keying (MPSK) OFDM. The /spl radic/M-ary ASK OFDM has the same peak-to-average-power ratio as that of the M-ary QAM OFDM. The MASK OFDM can be implemented digitally and efficiently by fast cosine transform and demodulated by inverse fast cosine transform. Comparisons show that implementation complexity is reduced for additive white Gaussian noise channels with the use of the new scheme.     

A novel orthogonal modulation format of D8PSK/ASK with differential bi-phase encoding and its application in a label switching optical network

The principle of a novel orthogonal modulation format of differential 8-level phase-shift keying amplitude-shift keying (D8PSK/ASK) with differential bi-phase encoding (DBC) is introduced. Based on it, an optical labeling scheme, in which the payload is 100 Gbit/s D8PSK signal and the label is 10 Gbit/s DBC-ASK signal, is proposed and simulated. The results are compared with other current schemes, and the effects of transmission range, modulation extinction ratio (ER) and received power on system performance are analyzed, respectively. The results show that the spectrum efficiency and bit error rate (BER) are improved greatly, and when the modulation ER is increased to 11 dB, the balanced performance between the payload and label is achieved.     

Stimulated Brillouin scattering excited by a modulated pump wave insingle-mode fibers

The effects of modulation on the gain of stimulated Brillouin scattering (SBS) are discussed. Three different modulation techniques, i.e. frequency shift keying (FSK), amplitude shift keying (ASK), and phase shift keying (PSK) are considered. The results show that the SBS threshold depends on the ratio between the spontaneous Brillouin linewidth and the bit rate. The SBS threshold for ASK and FSK is 6 dB higher at high bit rates, whereas the SBS threshold for PSK increases by 10dB for each factor of 10 increase in the bit rate     

Link-16信号MSK调制模式识别方法

针对Link-16信号采用的最小频移键控(MSK)调制模式,提出了一种基于瞬时特征参量与频谱特征的识别方法。该方法分2个层次进行调制识别,首先利用瞬时特征参量对幅移键控(ASK)、频移键控(FSK)和相移键控(PSK)、MSK信号进行识别,然后再利用频谱特征对MSK、PSK信号进行识别。最后,在特定的数据长度、信号幅度和信噪比的条件下,理论分析与仿真验证该算法易于实现、识别性能较好(90%)。     

CF-RZ-DPSK for suppression of XPM on dispersion-managed long-hauloptical WDM transmission on standard single-mode fiber

We present a new optical modulation format chirp-free return-to-zero differential phase shift keying (CF-RZ-DPSK), which enables wavelength-division-multiplexing (WDM) transmission at 10 Gb/s/ch at a channel spacing of 100 GHz over 3000 km without significant impairments due to cross-phase modulation (XPM). A transmitter setup is presented, which allows a simple implementation of CF-RZ-DPSK with two Mach-Zehnder modulators in push-pull operation. The robustness toward XPM is shown theoretically with the help of a simple analytical model for the XPM-induced phase modulation. The superior performance of CF-RZ-DPSK over other modulation formats [RZ-ampfitude shift keying (ASK), nonreturn-to-zero (NRZ)-DPSK, and NRZ-ASK, respectively] is clarified. Finally, simulation results for CF-RZ-DPSK in comparison to RZ-ASK show the superior performance of the newly proposed modulation format in a dense WDM setup     

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.     

Sensitivity penalty in multichannel coherent optical communications

The error rates and sensitivity penalties for multichannel coherent optical communications systems are evaluated for amplitude-shift keying (ASK), phase-shift keying (PSK), and frequency-shift keying (FSK) modulation, taking into account adjacent channel interference. Both time-domain and frequency-domain analysis are used, the latter being based on a Gaussian approximation. Both techniques yield similar results for sensitivity penalties below 1 dB. For FSK systems, larger values of the modulation index Δ do not necessarily lead to larger channel spacings. ASK and PSK systems both require larger channel spacings than FSK systems with Δ=1. The study was conducted for sources with linewidths narrow enough so that phase noise does not degrade the performance of receivers with matched filter demodulators     

Dynamic stimulated Brillouin scattering analysis

We present a new simple analysis-including the effect of spontaneous emission-of the (dynamic) influence of stimulated Brillouin scattering (SBS) on the detected receiver eye diagram. It applies in principle for general types of modulation formats such as the digital formats of amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK). The analysis is formulated for a determination of the signal power depiction and intersymbol interference (ISI) caused by the combined effect of fiber dispersion, fiber attenuation and nonlinear fiber effects such as the effect of self-phase modulation (SPM) and SBS. The analysis allows a quantification of the dithering influence on the SBS threshold. Representative numerical examples are presented for two single-channel ON-OFF modulated 10-Gh/s systems utilizing Franz-Keldysh and Mach-Zehnder-type modulators     

Transmission Performance Comparison of Direction Detection‐Based 100‐Gb/s Modulation Formats for Metro Area Optical Networks

Transmission performances of direct detection‐based 100‐Gb/s modulation formats are investigated and compared for metro area optical networks. The effects of optical signal‐to‐noise ratio sensitivity, chromatic dispersion, cross‐channel nonlinearity, and transmission distance on the performance of differential 8‐ary phase‐shift keying (D8PSK), differential phase‐shift keying plus three‐level amplitude‐shift keying (DPSK+3ASK), and dual‐carrier differential quaternary phase‐shift keying (DC‐DQPSK) are evaluated. The performance of coherent dual‐polarization quadrature phase‐shift keying (DP‐QPSK) with block phase estimation and coherent DP‐QPSK with digital differential detection are also presented for reference. According to our analysis, all three direct detection modulation formats could transmit a 100‐Gb/s signal over several hundred kilometers of a single‐mode fiber link. The results also show that DC‐DQPSK outperforms D8PSK and DPSK+3ASK, and the performance of DC‐DQPSK is comparable to that of coherent DP‐QPSK with digital differential detection. The maximum transmission distance of DC‐DQPSK is over 1,000 km, which is enough distance for metro applications.     

fso中一种光载波外差dpsk系统的设计

介绍了自由空间光通信中的相干通信系统,通过对相干光通信中振幅键控(ASK),频移键控(FSK),相移键控(PSK),差分相移键控(DPSK)四种光载波相干调制方式性能的分析和比较,仿真结果得出PSK调制误码性能更好,提出了一种光载波外差差分相移键控(DPSK)系统.     

A 46-GHz Direct Wide Modulation Bandwidth ASK Modulator in 0.13-μm CMOS Technology

A 46-GHz direct wide modulation bandwidth amplitude shift keying (ASK) modulator with an embedded voltage controlled oscillator (VCO) is proposed in this letter. This circuit is fabricated using a standard commercial bulk 0.13-mum CMOS technology and exhibits a modulation bandwidth wider than 1 GHz with a chip size of 390 times 480 mum². The recovered time-domain waveform shows a very good eye-pattern opening. To the best of the authors' knowledge, this is the first direct ASK modulator with an embedded VCO in the millimeter-wave regime using CMOS processes.     

8 Gbit/s FSK modulation of DFB lasers with optical demodulation

Single-contact DFB lasers were frequency modulated by pseudorandom data at rates up to 8 Gbit/s by direct current modulation with no pre-equalisation of the modulation signal. The signals were optically demodulated by Fabry-Perot interferometers for conversion to ASK signals which were detected by a direct-detection receiver. At 8 Gbit/s the receiver sensitivity was -22 dBm.<>