Dispersion-managed solitons: a new paradigm for high data rate

The WDM properties of dispersion managed (DM) solitons and the reduction in Gordon-Haus jitter means that it is possible to contemplate multiple channels each at 10 Gbit/s for transoceanic distances without the need for elaborate soliton control. This paper will concentrate on fundamental principles of DM solitons, but will use these principles to indicate optimum maps for future high-speed soliton systems.

Calculation of non-Gaussian statistics and bit error rate degradation due to pulse-to-pulse interaction

We develop a theoretical method to calculate jitter statistics of interacting solitons. Applying this approach, we have derived the non-Gaussian probability density function and calculated the bit-error rate as a function of noise level, initial separation and phase difference between solitons.

Optimum phase noise reduction and repetition rate tuning in quantum-dot mode-locked lasers

Competing approaches exist, which allow control of phase noise and frequency tuning in mode-locked lasers, but no judgement of pros and cons based on a comparative analysis was presented yet. Here, we compare results of hybrid mode-locking, hybrid mode-locking with optical injection seeding, and sideband optical injection seeding performed on the same quantum dot laser under identical bias conditions. We achieved the lowest integrated jitter of 121 fs and a record large radio-frequency (RF) tuning range of 342 MHz with sideband injection seeding of the passively mode-locked laser. The combination of hybrid mode-locking together with optical injection-locking resulted in 240 fs integrated jitter and a RF tuning range of 167 MHz. Using conventional hybrid mode-locking, the integrated jitter and the RF tuning range were 620 fs and 10 MHz, respectively. © 2014 AIP Publishing LLC.

Dynamics of quantum-dot mode-locked lasers with optical injection

We present the dynamics of quantum-dot passively mode-locked semiconductor lasers under optical injection. We discuss the benefits of various configurations of the master source including single, dual, and multiple coherent frequency sources. In particular, we demonstrate that optical injection can improve the properties of the slave laser in terms of time-bandwidth product, optical linewidth, and timing jitter.

Passively harmonic mode locked erbium doped fiber soliton laser with carbon nanotubes based saturable absorber

We have proposed and demonstrated passive harmonic mode locking of an erbium doped fiber laser with soliton pulse shaping using carbon nanotubes polyvinyl alcohol film. Two types of samples prepared by using filtration and centrifugation were studied. The demonstrated fiber laser can support 10th harmonic order corresponding to 245 MHz repetition rate with an output power of ~12 mW. More importantly, all stable harmonic orders show timing jitter below 10 ps. The output pulses energies are between 25 to 56 pJ. Both samples result in the same central wavelength of output optical spectrum with similar pulse duration of ~1 ps for all harmonic orders. By using the same laser configuration, centrifugated sample exhibits slightly lower pulse chirp. © 2012 Optical Society of America.

A lower bound on the per soliton capacity of the nonlinear optical fibre channel

A closed-form expression for a lower bound on the per soliton capacity of the nonlinear optical fibre channel in the presence of (optical) amplifier spontaneous emission (ASE) noise is derived. This bound is based on a non-Gaussian conditional probability density function for the soliton amplitude jitter induced by the ASE noise and is proven to grow logarithmically as the signal-to-noise ratio increases.

Realization of Differentiated Quality of Service for Wideband Code Division Multiple Access Core Network

The development of 3G (the 3rd generation telecommunication) value-added services brings higher requirements of Quality of Service (QoS). Wideband Code Division Multiple Access (WCDMA) is one of three 3G standards, and enhancement of QoS for WCDMA Core Network (CN) becomes more and more important for users and carriers. The dissertation focuses on enhancement of QoS for WCDMA CN. The purpose is to realize the DiffServ (Differentiated Services) model of QoS for WCDMA CN. Based on the parallelism characteristic of Network Processors (NPs), the NP programming model is classified as Pool of Threads (POTs) and Hyper Task Chaining (HTC). In this study, an integrated programming model that combines both of the two models was designed. This model has highly efficient and flexible features, and also solves the problems of sharing conflicts and packet ordering. We used this model as the programming model to realize DiffServ QoS for WCDMA CN. ^ The realization mechanism of the DiffServ model mainly consists of buffer management, packet scheduling and packet classification algorithms based on NPs. First, we proposed an adaptive buffer management algorithm called Packet Adaptive Fair Dropping (PAFD), which takes into consideration of both fairness and throughput, and has smooth service curves. Then, an improved packet scheduling algorithm called Priority-based Weighted Fair Queuing (PWFQ) was introduced to ensure the fairness of packet scheduling and reduce queue time of data packets. At the same time, the delay and jitter are also maintained in a small range. Thirdly, a multi-dimensional packet classification algorithm called Classification Based on Network Processors (CBNPs) was designed. It effectively reduces the memory access and storage space, and provides less time and space complexity. ^ Lastly, an integrated hardware and software system of the DiffServ model of QoS for WCDMA CN was proposed. It was implemented on the NP IXP2400. According to the corresponding experiment results, the proposed system significantly enhanced QoS for WCDMA CN. It extensively improves consistent response time, display distortion and sound image synchronization, and thus increases network efficiency and saves network resource.^

A multimodal and adaptive real-time human -computer interface for peoples with severe motor disability

This dissertation introduces the design of a multimodal, adaptive real-time assistive system as an alternate human computer interface that can be used by individuals with severe motor disabilities. The proposed design is based on the integration of a remote eye-gaze tracking system, voice recognition software, and a virtual keyboard. The methodology relies on a user profile that customizes eye gaze tracking using neural networks. The user profiling feature facilitates the notion of universal access to computing resources for a wide range of applications such as web browsing, email, word processing and editing. ^ The study is significant in terms of the integration of key algorithms to yield an adaptable and multimodal interface. The contributions of this dissertation stem from the following accomplishments: (a) establishment of the data transport mechanism between the eye-gaze system and the host computer yielding to a significantly low failure rate of 0.9%; (b) accurate translation of eye data into cursor movement through congregate steps which conclude with calibrated cursor coordinates using an improved conversion function; resulting in an average reduction of 70% of the disparity between the point of gaze and the actual position of the mouse cursor, compared with initial findings; (c) use of both a moving average and a trained neural network in order to minimize the jitter of the mouse cursor, which yield an average jittering reduction of 35%; (d) introduction of a new mathematical methodology to measure the degree of jittering of the mouse trajectory; (e) embedding an onscreen keyboard to facilitate text entry, and a graphical interface that is used to generate user profiles for system adaptability. ^ The adaptability nature of the interface is achieved through the establishment of user profiles, which may contain the jittering and voice characteristics of a particular user as well as a customized list of the most commonly used words ordered according to the user's preferences: in alphabetical or statistical order. This allows the system to successfully provide the capability of interacting with a computer. Every time any of the sub-system is retrained, the accuracy of the interface response improves even more. ^

56 Gb/s multi-band CAP for data center interconnects up to an 80 km SMF

We present the first (to the best of our knowledge) experimental demonstration of a 56 Gb/s multi-band carrierless amplitude and phase modulation (CAP) signal transmission over an 80-km single-mode fiber link with zero overhead pre-FEC signal recovery and enhanced timing jitter tolerance for optical data center interconnects.

Valores de referência de parâmetros acústicos para a voz normal no português europeu

O presente estudo tem como objetivo a caraterização acústica da voz normal para os falantes do Português Europeu, em termos de frequência fundamental, jitter, shimmer e relação sinal-ruído. São também analisadas as caraterísticas individuais que possam ter influência sobre a qualidade vocal, nomeadamente idade, género, índice de massa corporal, hábitos tabágicos e uso da voz no canto. Para tal, foram recolhidas amostras de fala de 363 indivíduos com uma voz avaliada como normal: 113 homens e 250 mulheres com idades compreendidas entre os 18 e os 91 anos. Amostras da produção sustentada da vogal /a/ foram analisadas acusticamente com o programa Praat, tendo sido extraídos os valores da média, mediana e desvio-padrão da frequência fundamental, jitter (ppq5), shimmer (apq11) e relação sinal-ruído. Os resultados obtidos apontam no sentido do género e a idade do indivíduo serem os fatores que maior influência exercem na voz, sendo que ambos os géneros apresentam um declínio da qualidade vocal ao longo da vida. As mulheres, globalmente, apresentam valores de frequência fundamental de 193,4±28,5 Hz (média ± desvio padrão da média), significativamente mais elevados que os homens, com valores de 120,7±22,3 Hz. Em termos de jitter, as mulheres obtiveram valores de 0,214±0,126 %, significativamente mais reduzidos que os 0,247±0,190 % obtidos para os homens. O shimmer não apresentou diferenças significativas entre géneros, sendo que os valores apresentados foram de 5,403±2,652 % para homens e 5,174±2,696 % para as mulheres. Relativamente à relação sinal-ruído, foram obtidos valores significativamente mais elevados nas mulheres, com 17,335±3,958 dB, tendo-se obtido para os homens 16,315±3,267 dB. Não foi encontrado um efeito significativo do índice de massa corporal, hábitos tabágicos e uso da voz no canto. Este trabalho disponibiliza novos dados para que a avaliação da voz em contexto clínico seja mais objetiva e eficaz.

ENABLING HARDWARE TECHNOLOGIES FOR AUTONOMY IN TINY ROBOTS: CONTROL, INTEGRATION, ACTUATION

The last two decades have seen many exciting examples of tiny robots from a few cm3 to less than one cm3. Although individually limited, a large group of these robots has the potential to work cooperatively and accomplish complex tasks. Two examples from nature that exhibit this type of cooperation are ant and bee colonies. They have the potential to assist in applications like search and rescue, military scouting, infrastructure and equipment monitoring, nano-manufacture, and possibly medicine. Most of these applications require the high level of autonomy that has been demonstrated by large robotic platforms, such as the iRobot and Honda ASIMO. However, when robot size shrinks down, current approaches to achieve the necessary functions are no longer valid. This work focused on challenges associated with the electronics and fabrication. We addressed three major technical hurdles inherent to current approaches: 1) difficulty of compact integration; 2) need for real-time and power-efficient computations; 3) unavailability of commercial tiny actuators and motion mechanisms. The aim of this work was to provide enabling hardware technologies to achieve autonomy in tiny robots. We proposed a decentralized application-specific integrated circuit (ASIC) where each component is responsible for its own operation and autonomy to the greatest extent possible. The ASIC consists of electronics modules for the fundamental functions required to fulfill the desired autonomy: actuation, control, power supply, and sensing. The actuators and mechanisms could potentially be post-fabricated on the ASIC directly. This design makes for a modular architecture. The following components were shown to work in physical implementations or simulations: 1) a tunable motion controller for ultralow frequency actuation; 2) a nonvolatile memory and programming circuit to achieve automatic and one-time programming; 3) a high-voltage circuit with the highest reported breakdown voltage in standard 0.5 μm CMOS; 4) thermal actuators fabricated using CMOS compatible process; 5) a low-power mixed-signal computational architecture for robotic dynamics simulator; 6) a frequency-boost technique to achieve low jitter in ring oscillators. These contributions will be generally enabling for other systems with strict size and power constraints such as wireless sensor nodes.

Acoustic analysis of vocal dysphonia

Voice acoustic analysis is becoming more and more usefúl in diagnosis of voice disorders or laryngological pathologies. The facility to record a voice sigiial is an advantage over other invasive techniques. This paper presents the statistical analyzes ofa set of voice parameters like jitter, shimmer and HNR over a 4 groups of subjects vvith dysphonia, fünctional dysphonia, hyperfünctional dysphonia, and psychogenic dysphonia and a control group. No statistical signifícance differences over pathologic groups were found but clear tendencies can be seen between pathologic and control group. The tendencies indicates this parameters as a good features to be used in an intelligent diagnosis system, moreover the jitter and shimmer parameters measured over different tones and vowels.

The effects of ILFN-exposure on voice acoustic parameters of commercial cabin crewmembers

Background: Long-term exposure to infrasound and low frequency noise (ILFN <500 Hz, including infrasound) can lead to the development of vibroacoustic disease (VAD). VAD is a systemic pathology characterized by the abnormal growth of extracellular matrices in the absence of inflammatory processes, namely of collagen and elastin, both of which are abundant in the basement membrane zone of the vocal folds. ILFN-exposed workers include pilots, cabin crewmembers, restaurant workers, ship machinists and, in previous studies, even though they did not present vocal symptoms, ILFN-exposed workers had significant different voice acoustic patterns (perturbation and temporal measures) when compared with normative population. Study Aims: The present study investigates the effects of age and years of occupational ILFN-exposure on voice acoustic parameters of 37 cabin crewmembers: 12 males and 25 females. Specifically, the goals of this study are to: 1) Verify if acoustic parameters change over the age and years of ILFN-exposure and 2) Determine if there is any interaction between age and years of ILFNexposure on voice acoustic parameters of crewmembers. Materials and Methods: Spoken phonatory tasks were recorded with a C420III PP AKG head-worn microphone and a DA-P1 Tascam DAT. Acoustic analyses were performed using KayPENTAX Computer Speech Lab and Multi-Dimensional Voice Program. Acoustic parameters included speaking fundamental frequency, perturbation measures (jitter, shimmer and harmonicto- noise ratio), temporal measures (maximum phonation time and s/z ratio) and voice tremor frequency. Results: One-way ANOVA analysis revealed that as the number of ILFN-exposure years increased male cabin crewmembers presented significant different shimmer values of /i/ as well as tremor frequency of /u/. Females presented significantly different jitter % of /i, a, O/ (p <0.05). Lastly, Two-way ANOVA analysis revealed that for females, there was a significant interaction between age and occupational ILFN-exposure for voice acoustic parameters, namely for jitter’s mean for /a, O/ and shimmer’s (%) mean for /a, i/ (p <0.05). Discussion and Conclusion: These perturbation measure patterns may be indicative of histological changes within the vocal folds as a result of ILFN-exposure. The results of this study suggest that voice acoustic analysis may be an important tool for confirming ILFN-induced health effects.

Voice acoustic profi le of males exposed to occupational infrasound and low-frequency noise

Background: Vibroacoustic disease (VAD) is a systematic pathology characterized by the abnormal growth of extra-cellular matrices in the absence of infl ammatory processes, namely collagen and elastin, both of which are abundant in the basement membrane zone of the vocal folds. VAD can develop due to long-term exposure to infrasound and low-frequency noise (ILFN, <500 Hz). Mendes et al. (2006, 2008 and 2012) revealed that ILFN-exposed males and females presented an increased fundamental frequency (F0), decreased jitter %, and reduced maximum phonation frequency range, when compared with normative data. Temporal measures of maximum phonation time and S/Z ratio were generally reduced. Study Aims: Herein, the same voice acoustic parameters of 48 males, 36 airline pilots and 12 cabin crewmembers (age range 25-60 years) were studied, and the effects and interaction of age and years of ILFN exposure were investigated within those parameters. ILFN-exposure time (i.e. years of professional activity) ranged from 3.5 to 36 years. Materials and Methods: Spoken and sung phonatory tasks were recorded with a DA-P1 Tascam DAT and a C420III PP AKG head-worn microphone, positioned at 3 cm from the mouth. Acoustic analyses were performed using KayPENTAX Computer Speech Lab and Multi-Dimensional Voice Program. Results: Results revealed that even though pilots and cabin crewmembers were exposed to occupational environments with distinct (ILFN-rich) acoustical frequency distributions and sound pressure levels, differences in the vocal acoustic parameters were not evident. Analyzing data from both professional groups (N = 48) revealed that F0 increased signifi cantly with the number of years of professional activity. Conclusion: These results strongly suggest that the number of years of professional activity (i.e. total ILFN exposure time) had a signifi cant effect on F0. Furthermore, they may refl ect the histological changes specifi cally observed on the vocal folds of ILFN-exposed professionals.

Holistic Design In High-Speed Optical Interconnects

Integrated circuit scaling has enabled a huge growth in processing capability, which necessitates a corresponding increase in inter-chip communication bandwidth. As bandwidth requirements for chip-to-chip interconnection scale, deficiencies of electrical channels become more apparent. Optical links present a viable alternative due to their low frequency-dependent loss and higher bandwidth density in the form of wavelength division multiplexing. As integrated photonics and bonding technologies are maturing, commercialization of hybrid-integrated optical links are becoming a reality. Increasing silicon integration leads to better performance in optical links but necessitates a corresponding co-design strategy in both electronics and photonics. In this light, holistic design of high-speed optical links with an in-depth understanding of photonics and state-of-the-art electronics brings their performance to unprecedented levels. This thesis presents developments in high-speed optical links by co-designing and co-integrating the primary elements of an optical link: receiver, transmitter, and clocking.

In the first part of this thesis a 3D-integrated CMOS/Silicon-photonic receiver will be presented. The electronic chip features a novel design that employs a low-bandwidth TIA front-end, double-sampling and equalization through dynamic offset modulation. Measured results show -14.9dBm of sensitivity and energy efficiency of 170fJ/b at 25Gb/s. The same receiver front-end is also used to implement source-synchronous 4-channel WDM-based parallel optical receiver. Quadrature ILO-based clocking is employed for synchronization and a novel frequency-tracking method that exploits the dynamics of IL in a quadrature ring oscillator to increase the effective locking range. An adaptive body-biasing circuit is designed to maintain the per-bit-energy consumption constant across wide data-rates. The prototype measurements indicate a record-low power consumption of 153fJ/b at 32Gb/s. The receiver sensitivity is measured to be -8.8dBm at 32Gb/s.

Next, on the optical transmitter side, three new techniques will be presented. First one is a differential ring modulator that breaks the optical bandwidth/quality factor trade-off known to limit the speed of high-Q ring modulators. This structure maintains a constant energy in the ring to avoid pattern-dependent power droop. As a first proof of concept, a prototype has been fabricated and measured up to 10Gb/s. The second technique is thermal stabilization of micro-ring resonator modulators through direct measurement of temperature using a monolithic PTAT temperature sensor. The measured temperature is used in a feedback loop to adjust the thermal tuner of the ring. A prototype is fabricated and a closed-loop feedback system is demonstrated to operate at 20Gb/s in the presence of temperature fluctuations. The third technique is a switched-capacitor based pre-emphasis technique designed to extend the inherently low bandwidth of carrier injection micro-ring modulators. A measured prototype of the optical transmitter achieves energy efficiency of 342fJ/bit at 10Gb/s and the wavelength stabilization circuit based on the monolithic PTAT sensor consumes 0.29mW.

Lastly, a first-order frequency synthesizer that is suitable for high-speed on-chip clock generation will be discussed. The proposed design features an architecture combining an LC quadrature VCO, two sample-and-holds, a PI, digital coarse-tuning, and rotational frequency detection for fine-tuning. In addition to an electrical reference clock, as an extra feature, the prototype chip is capable of receiving a low jitter optical reference clock generated by a high-repetition-rate mode-locked laser. The output clock at 8GHz has an integrated RMS jitter of 490fs, peak-to-peak periodic jitter of 2.06ps, and total RMS jitter of 680fs. The reference spurs are measured to be –64.3dB below the carrier frequency. At 8GHz the system consumes 2.49mW from a 1V supply.