Jitter Reduction Research Articles

SYNTHESIS OF STRUCTURES OF OPERATING DEVICES IMPLEMENTATION CRYPTOGRAPHIC ALGORITHMS IPSEC OF OPTIMIZED FOR MEDIA PACKAGES PROCESSIN

In the paper the operating device of IPSec protocol optimized for treatment media of packages is investigated. Analytical expressions which describe time of media packages processing depending on the parameters of operating device structure are offered, the mathematical model of operating device of IPSec processor is developed. On the basis of mathematical model, with the purpose of reduction of delay and jitter, which rise up during the generation of media package, software is developed for optimization of structures descriptions of processor IPSec operating device. The row of the optimized structures of operating device is got for different services of given IPSec treatment at different technological descriptions of component base. The analysis of results allowed to set that in most cases, the least time of treatment media of packages is observed at iterative and iterative-conveyer realization of IPSec operating device.

Coherent combining of multimillijoule parametric-amplified femtosecond pulses

We report on the first experimental realization of the coherent combining of multimillijoule parametric-amplified femtosecond pulses. An original two-channel laser system based on parametric amplification in β-BaB2O4 and LiB3O5 crystals was created. High-contrast laser pulses, with up to 100 mJ of energy and with a pulse duration of 23 fs, were generated in both channels. An original setup for active timing-jitter stabilization was developed. It allowed reduction of the relative timing jitter of the amplified pulses to 40 as, which enabled coherent combining with an efficiency as high as 95%. At the present time, this work demonstrates coherent combining of femtosecond pulses with both the highest energy and the shortest pulse duration.

Jitter reduction using native fiducials in rotating mirror ultra-fast microphotography.

Rotating mirror cameras represent a workhorse technology for high speed imaging in the MHz framing regime. The technique requires that the target image be swept across a series of juxtaposed CCD sensors, via reflection from a rapidly rotating mirror. Employing multiple sensors in this fashion can lead to spatial jitter in the resultant video file, due to component misalignments along the individual optical paths to each CCD. Here, we highlight that static and dynamic fiducials can be exploited as an effective software-borne countermeasure to jitter, suppressing the standard deviation of the corrected file relative to the raw data by up to 88.5% maximally, and 66.5% on average over the available range of framing rates. Direct comparison with industry-standard algorithms demonstrated that our fiducial-based strategy is as effective at jitter reduction, but typically also leads to an aesthetically superior final form in the post-processed video files.

Passive energy jitter reduction in the cascaded third harmonic generation process

In free electron laser (FEL) systems with ultraviolet (UV) laser driven injectors, a highly stable UV source generated through cascaded third harmonic generation (THG) from an infrared (IR) source is a key element in guaranteeing the acceptable current jitter at the undulator. In this letter, the negative slope of the THG efficiency for high intensity ultrashort IR pulses is revealed to be a passive stabilization mechanism for energy jitter reduction in UV. A reduction of 2.5 times the energy jitter in UV is demonstrated in the experiment and simulations show that the energy jitter in UV can be reduced by more than one order of magnitude if the energy jitter in IR is less than 3%, with proper design of the THG efficiency curve, fulfilling the challenging requirement for UV laser stability in a broad scope of applications such as the photoinjector of x-ray FELs.

0.6–2.7-Gb/s Referenceless Parallel CDR With a Stochastic Dispersion-Tolerant Frequency Acquisition Technique

A 0.6-2.7-Gb/s phase-rotator-based four-channel digital clock and data recovery (CDR) IC featuring a low-power dispersion-tolerant referenceless frequency acquisition technique is presented. A quasi-periodic reference clock signal extracted directly from a dispersed input signal is distributed to digitally controlled phase rotators in the CDR ICs for phase acquisition. A multiphase frequency acquisition scheme is employed for the reduction of the clock jitter. The measurement results show that the proposed design offers a lower frequency offset and clock noise floor under channel dispersion, as compared with conventional designs. The proposed four-channel digital CDR IC is fabricated in a 90-nm CMOS process. The figure of merit for a single channel is 8 mW/Gb/s such as a feedforward equalizer, a decision-feedback equalizer, and a referenceless CDR.

Generation of mode-locked optical pulses at 1035 nm from a fiber Bragg grating stabilized semiconductor laser diode

We report the generation of transform-limited, ~18 ps optical pulses from a fiber Bragg grating (FBG) stabilized semiconductor laser diode. Up to 7.2 pJ of pulse energy and a peak power of 400mW were achieved when operating at a repetition frequency of 832.6 MHz, a multiple of the cavity (diode + FBG) free spectral range (FSR). A small detuning in the repetition frequency resulted in broader optical pulses. We have shown experimentally the transition from a gain-switched regime of operation to mode-locked operation once the injection current modulation frequency is set to match a harmonic of the cavity FSR. The transition also results in a reduction in the timing jitter of the optical pulses.

Merkle tree‐based wormhole attack avoidance mechanism in low power and lossy network based networks

ABSTRACTSmart metering application has received a lot of attention from the research community lately. Usually, low power and lossy network runs on routing protocol for low power and lossy networks protocol, which constructs a directed acyclic graph structure for its normal operation. In this paper, we devise a wormhole attack scenario in such a network. Furthermore, we propose a Merkle tree‐based authentication mechanism, which runs on the notion of constructing a tree of hashed security information. We analyze the approach by formulating the wormhole attack scenario as a graph theoretic problem and show the effectiveness of the proposed Merkle tree‐based approach for authenticating communications. Furthermore, we perform simulations in network simulator 2 to observe the network performance by adopting a Merkle tree‐based approach to prevent from disrupting the links, and we observe better throughput, reduction in jitter, and end‐to‐end delay as compared with scenarios with wormhole attacks and no avoidance mechanism. In the end, we take a step toward optimizing the performance of the mechanism by proposing an effective tree traversal algorithm, which works on the notion of electing nodes as a root in a large scale network from where a Merkle tree will be originated. The mechanism with the traversal algorithm assists in managing the authentication in a huge network, which is broken down into many trees avoiding wormhole attacks in the network. Copyright © 2014 John Wiley & Sons, Ltd.

Optical beam transport to a remote location for low jitter pump-probe experiments with a free electron laser

In this paper we propose a scheme that allows a strong reduction of the timing jitter between the pulses of a free electron laser (FEL) and external laser pulses delivered simultaneously at the FEL experimental stations for pump-probe--type experiments. The technique, applicable to all seeding-based FEL schemes, relies on the free-space optical transport of a portion of the seed laser pulse from its optical table to the experimental stations. The results presented here demonstrate that a carefully designed laser beam transport, incorporating also a transverse beam position stabilization, allows one to keep the timing fluctuations, added by as much as 150 m of free space propagation and a number of beam folding mirrors, to less than 4 femtoseconds rms. By its nature our scheme removes the major common timing jitter sources, so the overall jitter in pump-probe measurements done in this way will be below 10 fs (with a margin to be lowered to below 5 fs), much better than the best results reported previously in the literature amounting to 33 fs rms.

Breakthroughs in Photonics 2013: Passive Mode-Locking of Quantum-Dot Lasers

Most recent achievements in passive mode-locking of quantum-dot lasers, with the main focus on jitter reduction and frequency tuning, are described. Different techniques, leading to record values for integrated jitter of 121 fs and a locking range of 342 MHz, are presented for a 40-GHz laser. Optical feedback is observed to be the method of choice in this field. For the first time, five different optical-feedback regimes are discovered, including the resonant one yielding a radio-frequency linewidth reduction by 99%.

Hybrid approach for loss recovery mechanism in OBS networks

This letter reports a study of a hybrid burst assembly and a hybrid burst loss recovery scheme (delay-based burst assembly and hybrid loss recovery (DBAHLR)) which selectively employs proactive or reactive loss recovery techniques depending on the classification of traffic into short term and long term, respectively. Traffic prediction and segregation of optical burst switching network flows into the long term and short term are conducted based on predicted link holding times using the hidden Markov model (HMM). The hybrid burst assembly implemented in DBAHLR uses a consecutive average-based burst assembly to handle jitter reduction necessary in real-time applications, with variations in burst sizes due to the non-monotonic nature of the average delay handled by additional burst length thresholding. This dynamic hybrid approach based on HMM prediction provides overall a lower blocking probability and delay and more throughput when compared with forward segment redundancy mechanism or purely HMM prediction-based adaptive burst sizing and wavelength allocation (HMM-TP).

단일 에지 이진위상검출기를 사용한 저 지터 클록 데이터 복원 회로 설계

본 논문은 CDR회로의 지터 감소를 위해 변형된 이진 위상검출기(뱅뱅위상 검출기- BBPD) 회로를 제안하였다. 제안된 PD는 하나의 에지를 사용함으로써 전압리플을 줄여, 제안한 PD를 적용하여 설계한 CDR회로는 감소된 지터 특성을 보였다. CMOS 0.13um 공정을 사용하여 설계하였고 제안한 위상검출기를 포함하는 클럭데이터 복원회로는 모의실험결과 16.9mW 전력소비에 peak-peak 지터는 10.96ps, rms 지터는 0.89ps을 보였다. This paper describes a modified binary phase detector (Bang-Bang phase detector - BBPD) for jitter reduction in clock and data recovery (CDR) circuits. The proposed PD reduces ripples in the VCO control voltage resulting in reduced jitter for CDR circuits. A 2.5 Gbps CDR circuit with a proposed BBPD has been designed and verified using Dongbu <TEX>$0.13{\mu}m$</TEX> CMOS technology. Simulation shows the CDR with proposed PD recovers data with peak-to-peak jitter of 10.96ps, rms jitter of 0.86ps, and consumes 16.9mW.

Phase noise and jitter reduction by optical feedback on passively mode-locked quantum-dot lasers

The noise properties of the pulse trains of passively mode-locked 40 GHz quantum-dot lasers subject to optical feedback are investigated in detail. Five different feedback regimes are discovered and the clearly identified regime of resonant optical feedback is further examined. The feedback parameters yielding minimum phase noise are determined. Here, the radio-frequency (RF)-line-width is reduced from its original value by 99% to 1.9 kHz. The corresponding pulse-to pulse jitter of 23 fs is a record low value for passively mode-locked 40 GHz quantum-dot lasers.

Analysis of Self-Pulsating Sources Based on Regenerative SPM: Ignition, Pulse Characteristics and Stability

We provide design guidelines and resulting outputs of a self-pulsating source based on regenerative self-phase modulation and offset band-pass filtering. We assess the conditions for self-pulsation and discuss the output pulse properties under the influence of spectral separation between the filters and their bandwidth. We also examine the source behavior when the central wavelength of the bandpass filters are subject to increasing spectral separation in the pulse-buffering regime. The results emphasize the role of chromatic dispersion for the reduction of amplitude and timing jitter.

A 5 Gb/s Single-Ended Parallel Receiver With Adaptive Crosstalk-Induced Jitter Cancellation

This paper presents an adaptive far-end crosstalk cancellation scheme for a single-ended parallel receiver. The adaptation engine is embedded in a single representative channel CDR, and the receiver efficiently reduces the crosstalk noise with a minimal cost in hardware and power consumption. In addition, the proposed scheme can be applied to any given CDR and equalizing circuits. The receiver is fabricated in 0.13 μm CMOS technology and achieves a reduction of FEXT-induced jitter up to 75%. The receiver consumes 65 mW at 5 Gb/s (4.3 mW/Gb/s/pin) including a PLL for global clock distribution.

Procedure for applying QoS mechanisms in NGN's access layers, for voice services

Currently all services converge into a Next Generation Network and considering that today the requirements about quality of service are more stringent because of the same user requirements, it is necessary to propose a procedure of QoS to ensure an efficient operation of transporting the most critical services and real time; as the voice, ensuring the reduction of latency, jitter, packet loss and Eco. The CRC (Regulatory Commission of Communications) in Colombia applies the provisions of QoS for they can be used by telecommunications operators and they must be conform to the recommendations Y.1540 and Y.1541 ITU-T (International Telecommunication Union). The aim of this paper is to present a procedure for applying QoS mechanisms in NGN network in xDSL access in order to maintain quality of service in Voice over IP (VoIP), which allows economic and technically efficient provision of VoIP for customer and the telecommunications operator.

Timing jitter reduction of passively mode-locked semiconductor lasers by self- and external-injection: Numerical description and experiments

In this paper the influence of different feedback (FB) and synchronization schemes on the timing phase noise (TPN) power spectral density (PSD) of a quantum-dot based passively mode-locked laser (MLL) is studied numerically and by experiments. The range of investigated schemes cover hybrid mode-locking, an opto-electrical feedback configuration, an all-optical feedback configuration and optical pulse train injection configuration by means of a master MLL. The mechanism responsible for TPN PSD reduction in the case of FB is identified for the first time for monolithic passively MLL and relies on the effective interaction of the timing of the intra-cavity pulse and the time-delayed FB pulse or FB modulation together with an statistical averaging of the independent timing deviations of both. This mechanism is quantified by means of simulation results obtained by introducing an universal and versatile simple time-domain model.

A 6.5-Gb/s 1-mW/Gb/s/CH Simple Capacitive Crosstalk Compensator in a 130-nm Process

A capacitive crosstalk compensator (CXC) at a transmitter is presented. It employs double-path capacitive coupling to cancel accurately crosstalk-induced jitter. A mode detector and an additional clock for compensation are eliminated, and only buffers and capacitors are used. The simple architecture consumes low power (1 mW/Gb/s/CH) and occupies small area (0.009 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /CH). The chip was fabricated in a 130-nm CMOS process. CXC has the maximum jitter reduction of 34.1 ps (90.5%) and the maximum voltage improvement of 26.6 mV. CXC operates at up to 6.5 Gb/s.

Feedback and harmonic locking of slot-type optomechanical oscillators to external low-noise reference clocks

We demonstrate feedback and harmonic locking of chip-scale slot-type optomechanical oscillators to external low-noise reference clocks, with suppressed timing jitter by three orders of magnitude. The feedback and compensation techniques significantly reduce the close-to-carrier phase noise, especially within the locking bandwidth for the integral root-mean-square timing jitter. Harmonic locking via high-order carrier signals is also demonstrated with similar phase noise and integrated root-mean-square timing jitter reduction. The chip-scale optomechanical oscillators are tunable over an 80-kHz range by tracking the reference clock, with potential applications in tunable radio-frequency photonics platforms.

Analog Circuit for Timing Measurements With Large Area SiPMs Coupled to LYSO Crystals

The most common method for time pick-off from signals coming from SiPMs coupled to scintillator crystals in PET applications is the Leading Edge Triggering. In this work we propose a new filtering scheme to be applied before the discriminator. It implements a type of baseline compensation aimed at the reduction of the time jitter due to the dark counts of the detector and is based on a simple analog filter, which is well suited for an ASIC implementation. We describe a circuit, built with discrete components, that implements the filter. Finally we report on the Coincidence Resolving Time measurements performed coupling the circuit to the real detector, composed of a SiPM built at FBK and a LYSO crystal, for the detection of 511 keV photons. The results obtained are promising, showing that the method is quite effective in reducing the impact of the detector noise on the timing performance of the system.

Jitter reduction of a reaction wheel by management of angular momentum using magnetic torquers in nano- and micro-satellites

Nowadays, nano- and micro-satellites, which are smaller than conventional large satellites, provide access to space to many satellite developers, and they are attracting interest as an application of space development because development is possible over shorter time period at a lower cost. In most of these nano- and micro-satellite missions, the satellites generally must meet strict attitude requirements for obtaining scientific data under strict constraints of power consumption, space, and weight. In many satellite missions, the jitter of a reaction wheel degrades the performance of the mission detectors and attitude sensors; therefore, jitter should be controlled or isolated to reduce its effect on sensor devices. In conventional standard-sized satellites, tip-tilt mirrors (TTMs) and isolators are used for controlling or isolating the vibrations from reaction wheels; however, it is difficult to use these devices for nano- and micro-satellite missions under the strict power, space, and mass constraints. In this research, the jitter of reaction wheels is reduced by using accurate sensors, small reaction wheels, and slow rotation frequency reaction wheel instead of TTMs and isolators. The objective of a reaction wheel in many satellite missions is the management of the satellite’s angular momentum, which increases because of attitude disturbances. If the magnitude of the disturbance is reduced in orbit or on the ground, the magnitude of the angular momentum that the reaction wheels gain from attitude disturbances in orbit becomes smaller; therefore, satellites can stabilize their attitude using only smaller reaction wheels or slow rotation speed, which cause relatively smaller vibration. In nano- and micro-satellite missions, the dominant attitude disturbance is a magnetic torque, which can be cancelled by using magnetic actuators. With the magnetic compensation, the satellite reduces the angular momentum that the reaction wheels gain, and therefore, satellites do not require large reaction wheels and higher rotation speed, which cause jitter. As a result, the satellite can reduce the effect of jitter without using conventional isolators and TTMs. Hence, the satellites can achieve precise attitude control under low power, space, and mass constraints using this proposed method. Through the example of an astronomical observation mission using nano- and micro-satellites, it is demonstrated that the jitter reduction using small reaction wheels is feasible in nano- and micro-satellites.