Crosstalk Power Research Articles

Time and Modulation Frequency Dependence of Crosstalk in Homogeneous Multi-Core Fibers

This study presents an evaluation of the time and modulation frequency-varying power transfer of crosstalk in a homogeneous multi-core fiber (MCF). Experimental observations using a seven-core MCF over a period of 10 h show that, unlike localized crosstalk, distributed crosstalk power transfer has a pronounced modulation frequency response which changes substantially over time. This response is described using an adaptation of previous crosstalk models for MCFs showing that it results from the random time-varying interference between crosstalk contributions generated at a discrete number of phase matching points along the fiber. The model is used to produce simplified empirical models to characterize its average and variance. It is shown that both these quantities are nonzero and nearly constant for modulation frequencies above the inverse of the time skew between cores. These observations are validated by experimental data.

Effects of non-Kolmogorov turbulence on the spiral spectrum of Hypergeometric-Gaussian laser beams.

We study the effects of non-Kolmogorov turbulence on the orbital angular momentum (OAM) of Hypergeometric-Gaussian (HyGG) beams in a paraxial atmospheric link. The received power and crosstalk power of OAM states of the HyGG beams are established. It is found that the hollowness parameter of the HyGG beams plays an important role in the received power and crosstalk power. The larger values of hollowness parameter give rise to the higher received power and lower crosstalk power. The results also show that the smaller OAM quantum number and longer wavelength of the launch beam may lead to the higher received power and lower crosstalk power.

Analytical Analysis of In-Band Crosstalk, Out-of-Band Crosstalk and GVD-Based Power Penalties in DWDM and TDM/DWDM-PONS

In addition to the ever-increasing demand for broader bandwidth per user, which results from the continuous development of new bandwidth-hungry services and applications, the consequent upgrade from the currently deployed Time-Division Multiplexing Passive Optical Networks (TDM-PONs) to Next-Generation Optical Access Networks (NG-OANs) has become inevitable. Different architectures for creating a NG-OAN have been proposed in the literature. Among those architectures, the DWDM and TDM/DWDM-Based OANs are very promising candidates. They were mainly proposed to exploit the large wavelength counts available in the fibre (its virtual unlimited bandwidth) to achieve a significant increase in the system capacity. Moreover, they allow coexistence in an open access environment among different network operators. In this study, we first analyze the impact of in-band crosstalk, out-of-band crosstalk to evaluate the performance of the Arrayed Waveguide Grating (AWG). The reason to focus on the AWG is due to this optical device is used almost in all DWDM and TDM/WDM-PONs. We then turn our attention to analyze the impact of group velocity dispersion GVD to estimate the maximum allowable bit rate for optical transmission without the need for using a Dispersion Management Technique (DMT) and/or a Forward Error Correction Technique (FECT). The analysis was performed using Matlab software (The Math works, Inc., Natick, MA, USA) and confirms that the in-band crosstalk has a stronger effect than the out-of-band crosstalk because its noise floor is reached at a lower crosstalk noise and with fewer crosstalk components. The in-band crosstalk noise should be kept below -37 dB and -34 dB to maintain a power penalty of less than 1 dB if 15 and 7 in-band crosstalk components are considered, respectively. The out-of-band crosstalk noise should be kept below -20.3 dB and -17.18 dB to maintain a power penalty of less than 1 dB if 240 and 56 out-of-band crosstalk components are considered, respectively. It was observed that the GVD noise floor is reached at a shorter fiber length as the bit rate increases and it was confirmed that a significant improvement in which the GVD noise floor is reached at longer fiber can be achieved if an externally modulated, small spectral-width source is used when a bit rate of 622 Mbps, 1 Gps, or 2.5 Gbps is used. However, a dispersion management technique becomes necessary if the bit rate increases to 10 Gbps or more.

Properties of power dependence on low-crosstalk waveband conversion with an apodized multiperiod-QPM LiNbO_3 device

Quasi-phase-matched (QPM) LiNbO₃ devices having a multiperiod-periodically-poled structure, which we call multiperiod-QPM LiNbO₃ devices, are capable of shifting the idler waveband during waveband conversion via cascaded difference-frequency generation (cascaded DFG). However, these multiperiod-QPM devices have a problem that they produce extra ripples between QPM peaks in the phase-matching curve. These ripples cause crosstalk between wavebands arising from sum-frequency generation (SFG) between the signal and idler wavebands and subsequent DFG between the SFG wavelength and the signal waveband. To decrease the size of the ripples and thus that of the crosstalk, an apodized multiperiod-QPM device is developed. In demonstrating waveband conversion for low crosstalk with this device, we measure the dependence of the idler power, the crosstalk power, and their ratio on the signal power. This measurement shows that it agrees well with theoretical prediction and that the obtained feature of crosstalk reduction is kept even for decreased signal power.

Capacitively-Coupled SQUID Bias for Time Division Multiplexing

The multiplexing scheme presented in this paper is part of the readout chain of the QUBIC instrument devoted to cosmic microwave background polarization observations. It is based on time domain multiplexing using superconducting quantum interference devices (SQUIDs) to read out a large array of superconducting bolometers. The originality of the multiplexer presented here lies in the use of capacitors for the SQUID addressing. Capacitive coupling allows us to bias many SQUIDs in parallel (in a 2D topology), with low crosstalk and low power dissipation of the cryogenic front-end readout. However, capacitors in series with the SQUID require a modification of the addressing strategy. This paper presents a bias reversal technique adopted to sequentially address the SQUIDs through capacitors using a cryogenic SiGe integrated circuit. We further present the different limitations of this technique and how to choose the proper capacitance for a given multiplexing frequency and current source compliance.

Verification of the analytical equation for power penalty measurement in OXADM device

This paper presents a computational investigation of OXADM device for measuring power penalty. The OXADM are located in the nodes, which have more than two switching directions in ring networks. The function of OXADM is to flexibly switch the wavelengths among the different input and output ports. Because of the OXADM’s imperfect performance, the insertion loss and crosstalk are induced in the system. This paper highlights the verification of analytical modeling method which is used to analyze the OXADM structure in crosstalk or leakage power that leads to the power penalty. The power penalty depends on few parameters but our investigation here focused on a number of operating wavelengths input and output ports, ratio of optical power as well as, the Q factor.The variation of this parameters will affect the amount of the desired power penalty. Key words: OXADM, analytical, verification, power penalty, crosstalk.

In-Band Crosstalk Transmission Penalties on 112-Gb/s PDM-QPSK Optical Links

We demonstrate a method of quantifying the penalty of in-band crosstalk that accounts for the varying spectral content. Experimentally evaluated penalties for widely varying crosstalk spectral content are shown to be readily predetermined based on the crosstalk spectral content and power within a single 112 Gb/s polarization-division multiplexing quadrature phase-shift keying (PDM-QPSK) link. Optical signal-to-noise ratio (OSNR) penalties predicted using a weighted crosstalk correlated with experimental results to within 1 dB for 8 spans AllWave [standard single-mode fiber (SSMF)] or TrueWave [nonzero dispersion fiber (NZDF)] links with different dispersion maps. Moreover, we identify a nonlinearity-enhanced crosstalk effect that is evident in the nonlinear transport regime and induce additional crosstalk-induced ONSR penalty.

Power Penalty Assessment of OXADM Device Model - Analytical Analysis

This OXADM are located in the nodes, which have more than two switching directions in ring networks. The function of OXADM is to flexibility switch the wavelengths among the different input and output ports. Because of the OXADM's imperfect performance, the insertion loss and crosstalk are induced in the system. Analytical modeling method is using to analyze the OXADM structure in crosstalk or power leakage that lead to the power penalty. To overcome this problem, power penalty is needed to be supplied. The insertion of this power penalty depends on few parameters. The parameters that we going to investigate here will be in term of number of operating wavelengths and number of input/output ports as well as the Q factor. The variation of this parameters will affects the amount of the desired power penalty. Simulation results in higher crosstalk or higher power penalty needed as the number of OXADM increases. As the sum of the wavelength and the number of input/output for each OXADM increases, the power penalty will increased as well. Investigation on the maximum Q factors is 6 to get the minimum power penalty at the lowest BER for most of the combination of the sum of the wavelength and the number of input/output for each OXADM.

Reliable network-on-chip design for multi-core system-on-chip

Network-on-chip (NoC) architectures must deliver good latency-through put performance in the face of tight power and area budgets. However, in high-performance chip design, a significant design challenge is how to fulfill the requirements of circuit noise elimination, since the faults will slow down performance and dissipate much of the overall system power. This paper presents a simple coding scheme for reducing power dissipation, crosstalk noise, and crosstalk delay on the bus while simultaneously detecting errors at runtime. It uses a simple bus-invert encoding technique to reduce the prohibited transitions in terms of crosstalk noise and power dissipation. We also design a corresponding detector to detect errors at the input of the NoC routers. It can save energy by interrupting communications without storing and routing the packets when errors occur during transmissions. The experimental results for various multimedia applications show significant reduction in the number of patterns that are most likely to produce crosstalk errors. The results also show that it is attractive in terms of cost to apply the detecting logic to routers in the NoC with respect to the power consumption.

Interferometric Crosstalk Reduction in an RSOA-Based WDM Passive Optical Network

Reflection and Rayleigh backscattering-induced interferometric crosstalk in a link employing a reflective semiconductor optical amplifier (RSOA) may cause significant power penalty and, thus, limit the performance of the system. In this paper, we investigate interferometric crosstalk suppression in a centralized light generation wavelength division multiplexing-passive optical network (WDM-PON) by single-tone phase modulation either by utilizing the nonlinear behavior of the RSOA at the optical network unit (ONU) or by applying an external phase modulator at the source side. 6- and 7-dB reduction in power penalty for reflection-induced crosstalk is achieved, respectively. For Rayleigh backscattering-induced crosstalk power penalty is improved with 3 and 4.5 dB, respectively. The results show that an RSOA is very sensitive to reflections and backscattering and the tolerance to these impairments can be significantly improved by appropriate phase modulation. A comparison with advantages and disadvantages of both methods together with final recommendation is also given in the paper.

Performance Limitations of Subcarrier Multiplexed WDM Signal Transmissions Using QAM Modulation

We theoretically investigate the performance limitations of subcarrier multiplexed (SCM) wavelength-division-multiplexing (WDM) systems using optical double-sideband (DSB) modulated, 16-quadrature amplitude-modulated (QAM) signals. The performance limitations are investigated using crosstalk power and SCM channel spacing for various transmission conditions, including impairment factors such as dispersion and fiber nonlinearities for a single wavelength channel first. The effects of WDM channel spacing on SCM systems with multiwavelength channels are also evaluated via the calculated bit error rate (BER) performance, based on the performance limitations found in the single-wavelength simulation. This enables us to provide guidelines for the design of SCM/WDM systems for fiber-to-the-home (FTTH) network in WDM-passive optical network (PON) architecture, based on the performance limitations.

Crosstalk-free design for the intersection of two dielectric waveguides

We propose an efficient method to reduce the crosstalk, reflection and radiation at the crossing of two dielectric waveguides in a on-chip optical interconnect network. By increasing the vertical thickness of the guides locally in the crossing region, we create better mode-matching interfaces that dramatically reduce losses. The idea is demonstrated using numerical simulations. More than 95% crosstalk power reduction and 90% reflection power reduction are observed, while the radiation power can be reduced by 40%. The method is compatible with the planar integrated circuit technique.

광 이중 측파대 변조 방식과 16 QAM 신호를 이용한 부반송파/파장 분할 다중화 시스템의 성능 분석에 대한 연구

본 논문에서는 광 이중 측파대역 변조 방식과 16 QAM(Quadrature Amplitude Modulation) 신호를 이용한 부반송파/파장 분할 다중화 시스템의 성능을 부반송파 채널 간격, 누화 전력 량(crosstalk power), BER(Bit-Error Rate) 특성을 통해 연구하고 있다. 광 전송 링크에서 분산 특성과 자기 위상 변조, 상호 위상 변조와 같은 비선형 현상을 고려하였을 때 BER특성을 살펴보았다. 컴퓨터 시뮬레이션 결과, 부반송파/파장 분할 다중화 시스템의 성능을 결정짓는 주도적인 인자는 마흐-젠더 변조기의 비선형 특성과 부반송파 채널 간격으로 관찰되었다. 광섬유의 분산에 의한 영향만 고려했을 때는 전송거리가 증가함에 따라 높은 주파수에 있는 부반송파 채널의 BER 성능이 나빠졌으나, 분산과 비선형 효과를 함께 고려되었을 경우 광섬유에 입사하는 전력이 클 때 높은 주파수에 있는 부반송파 채널에서 약간의 BER 성능 향상을 확인할 수 있었다. In this paper, we investigate the performance limitations of SubCarrier Multiplexed(SCM) WDM systems using optical Double-Side Band(DSB) modulated 16 QAM signals. The Bit-Error Rate(BER) performance is evaluated under various optical transmission links including the effects of the dispersion and fiber nonlinearities such as SPM(Self-Phase Modulation) and XPM(cross-phase modulation). After simulation of SCM-WDM systems, the dominant factors determining the entire system performance are appeared to be the nonlinearity of MZ(Mach-Zehnder) modulator and the SCM channel spacing. The BER performance of subcarrier channels in the higher frequencies was degraded with the large dispersion effect only, however, the performance was improved a little with a combined effect of fiber dispersion and nonlinear effect when the hish fiber launching power was applied.

A 3.125Gbit/s Parallel Optical Receiver in 0.13-{mu} CMOS with Direct Crosstalk Power Penalty Measurement Capability

We introduce a new method to measure the crosstalk power penalty in an arrayed environment by using an on-chip pseudorandom-bit-sequence generator to drive the aggressors. The proposed method is implemented in a three-channel 3.125-Gbit/s/ ch parallel receiver. Experimental results are presented including measurements of bit-error rate and crosstalk power penalty for 2.5and 3.125-Gbit/s operations. The measured crosstalk power penalty is less than 1 dB at both data rates. The test chip was designed in a standard 0.13-mum CMOS process

DELAY AND ENERGY EFFICIENT CODING TECHNIQUES FOR CAPACITIVE INTERCONNECTS

In the current era of deep-submicron technology (DSM), minimizing the propagation delay and energy consumption on buses is the most important design objective in system-on-chip (SOC) designs. In particular, coupling effects between wires on the bus can cause serious problems such as cross-talk delay, noise, and power dissipation. Most of the work reported in literature so far concentrates on either minimizing the energy consumption or the delay. In this paper, the authors propose two coding techniques for achieving energy and delay efficiency in data transmission on on-chip buses. It is shown, using SPEC 2000 benchmark suit, that the proposed techniques achieve an energy saving of 35% or over the un-encoded data on the data bus and eliminate cross-talk-delay classes 6, 5, and 4.

All-optical multi-wavelength conversion using absorption modulation of an injection-locked FP-LD

An all-optical multi-wavelength converter using absorption modulation of an injection-locked Fabry-Perot laser diode (FP-LD) is demonstrated at 2.5Gb/s. The multi-wavelength converter can simultaneously provide 1 to 4 channel outputs and support both inverted and non-inverted conversion. By optimizing the wavelength of pump signal and polarization states of pump, probes, and the FP-LD, all converted outputs show high extinction ratio and negligible crosstalk power penalty. The results guarantee to increase the number of output channels. The proposed scheme can be applied to multicasting functions as well as 1xN wavelength conversion in an all-optical wavelength division multiplexed network.

A 3.125-Gbit/s Parallel Optical Receiver in 0.13-<formula formulatype="inline"><tex>$\mu{\hbox {m}}$</tex></formula> CMOS With Direct Crosstalk Power Penalty Measurement Capability

We introduce a new method to measure the crosstalk power penalty in an arrayed environment by using an on-chip pseudorandom-bit-sequence generator to drive the aggressors. The proposed method is implemented in a three-channel 3.125-Gbit/s/ ch parallel receiver. Experimental results are presented including measurements of bit-error rate and crosstalk power penalty for 2.5and 3.125-Gbit/s operations. The measured crosstalk power penalty is less than 1 dB at both data rates. The test chip was designed in a standard 0.13-mum CMOS process

Crosstalk Models for Short VDSL2 Lines from Measured 30 MHz Data

In recent years, there has been a growing interest in hybrid fiber-copper access solutions, as in fiber to the basement (FTTB) and fiber to the curb/cabinet (FTTC). The twisted pair segment in these architectures is in the range of a few hundred meters, thus supporting transmission over tens of MHz. This paper provides crosstalk models derived from measured data for quad cable, lengths between 75 and 590 meters, and frequencies up to MHz. The results indicate that the log-normal statistical model (with a simple parametric law for the frequency-dependent mean) fits well up to MHz for both FEXT and NEXT. This extends earlier log-normal statistical modeling and validation results for NEXT over bandwidths in the order of a few MHz. The fitted crosstalk power spectra are useful for modem design and simulation. Insertion loss, phase, and impulse response duration characteristics of the direct channels are also provided.

Performance analysis for an all-optical wavelength converter using four-wave mixing (FWM) in a single mode fiber

An analytical approach is presented to determine the performance of a tunable wavelength converter based on four wave mixing (FWM) in a single mode fiber (SMF) with two pump lasers. The analysis is carried out for an intensity modulated (IM) signal taking into considerations the effects of spectral broadening due to FWM and laser phase noise. The results evaluated at a bit rate of 10 Gb/s show that the signal power is substantially higher at lower values of wavelength separation. For example, for input powers of 10 mW each, wavelength separation of 4 nm between the pump-2 and the input signal, the output converted power is found to be -10 dBm corresponding to wavelength separation of 2 nm between pump-1 and converter signal. The corresponding crosstalk power is found to be -25 dBm at a channel separation of 3 times bit rate.

Methods of summing crosstalk from mixed sources .II. Performance results

For pt.I see ibid., vol.50, p.453-61, (Mar. 2002). In a companion paper, the problem of summing crosstalk from mixed sources has been deeply analyzed. The problem of determining a good model for the summation of mixed crosstalk is becoming more important now that many digital subscriber line (DSL) services are being deployed in the field. The straightforward application of the usual 1% worst-case model for only one kind of disturber to all the individual worst-case contributions is overly pessimistic. The most well-known methods of summing mixed crosstalk, the FSAN and the Mean PSD methods, are less pessimistic. Also, the two new summation methods presented previously, the Minkowski-bound and the Holder-bound methods, are less pessimistic and offer the appealing feature of choosing the level of pessimism or optimism through a parameter. However, the accuracy of these methods has never been quantified in the past. As more and more types of DSLs are deployed by multiple service providers, it is imperative to gain confidence in the methods of modeling worst-case mixed crosstalk and to understand their limitations. In this paper, the problem of defining an accurate statistical modeling of the pair-to-pair crosstalk power coupling losses is addressed first. This has been accomplished by exploiting a large measurement campaign performed on real cables. The results of a large simulation campaign that compares the accuracy of known and newly proposed methods of summing mixed crosstalk are then presented. In addition, it is proposed here to use the signal-to-noise ratio (SNR) as the metric for determining the actual system performance in the presence of mixed crosstalk. A Monte Carlo simulation is run that assigns randomly each disturber to a pair-to-pair NEXT coupling which matches the statistics of measured cables. The Monte Carlo method accurately determines the I % worst-case impact on the SNR of DSL systems affected by mixed crosstalk. ISDN, HDSL, HDSL2, T1 and ADSL are each simulated with many different numbers and types of mixed crosstalk.