This thesis reports an experimental characterization of the ultrafast gain and refractive index dynamics of a novel InAs/InGaAsP/InP quantum-dot (QD) semiconductor optical amplifier (SOA) operating near 1.55-µm wavelengths, assessing its high-speed performance characteristics for the first time. The thesis also studies the influence of the degree of quantum confinement on the dynamics of SOAs by comparing the zero-dimensional (0-D) QD's dynamics to those in 1-D InAs/InAlGaAs/InP quantum-dash (QDash), and 2-D InGaAsP/InGaAsP/InP quantum-well (QW) SOAs, both of which also operate near 1.55-µm wavelengths, and are made with matching or similar materials and structures. The ultrafast (around 1 ps) and long-lived (up to 2 ns) amplitude and phase dynamics of the SOAs are characterized via advanced heterodyne pump-probe measurements with 150-femtosecond resolution. It is found that the QD SOA has an 80-picosecond amplitude, and 110-picosecond phase recovery lifetime in the gain regime, 4-6 times faster than the QDash and QW recovery lifetimes, as well as reduced ultrafast transients, giving it the best properties for high-speed (> 100 Gb/s) all-optical signal processing in the important telecommunications wavelength bands. An impulse response model is developed and used to analyze the dynamics, facilitating a comparison of the gain compression factors, time-resolved linewidth enhancement factors (alpha-factors), and instantaneous dynamic coefficients (two-photon absorption and nonlinear refractive-index coefficients) amongst the three structures. The quantum-dot device is found to have the lowest effective alpha-factor, 2-10, compared to 8-16 in the QW, as well as time-resolved alpha-factors lower than in the QW—promising for reduced-phase-transient operation at high bitrates. Significant differences in the alpha-factors of lasers with the same structure are found, due to the differences between gain changes that are induced optically or through the electrical bias. The relative contributions of stimulated transitions and free-carrier absorption to the total carrier heating dynamics in SOAs of varying dimensionality are also reported for the first time. Examining the QD electroluminescence and linear gain spectra in combination with the carrier dynamics also brings about conclusions on the nature of the quantum confinement, dot energy-level structure, and density of states—aspects of the material that have not been previously well understood.

Shoulder arthroplasty surgery has shown remarkable progress during the last few decades. A number of factors affect postoperative range of motion, pain and prosthetic durability. Among these factors, the length of the lever arm and joint stability is the ones that can be altered by the selected prosthetic component. It is uncertain how much of the normal anatomy needs to be re-established. Stemless prostheses with total reliance on metaphyseal fixation were introduced in France in 2004 (TESS, Zimmer Biomet). The goals were to avoid stem-related complications. Stemless implants have other potential benefits, including the ability to restore shoulder anatomy. Study I: This is a prospective cohort study of 49 patients with one of two versions of the TESS prosthesis (anatomical or reverse) with clinical and radiological follow-up ranging from 9–24 months. The TESS prosthesis showed short-term results that were comparable with other shoulder prosthetic systems. Study II: This is a prospective comparative non-randomised study of 37 patients (40 shoulders) who underwent TESS reverse shoulder arthroplasty (RSA) with a follow-up ranging from 15–66 months. We found a significant improvement in functional outcome and reduction of pain in both stemmed and stemless groups. Glenoid overhang influenced the occurrence of scapular notching (SN). Study III: This is a radiological study showing that CT had a good reliability and reproducibility in estimating LHO. Study IV: This is a prospective radiological study of 69 patients (70 shoulders) with primary osteoarthritis (OA) who had undergone stemless total anatomical shoulder arthroplasty (TSA). This study showed that stemless anatomical TSA could be useful in restoring shoulder anatomy. Study V: This is a prospective study of 44 patients with OA who had undergone stemless anatomical TSA with a clinical and radiological follow up ranging from 12 – 50 months. Our study showed that LHO reconstruction close to the anatomy of a healthy contralateral shoulder improved shoulder function. Stemless anatomical TSA help to restore LHO. Increasing LHO may have a negative effect on shoulder function at three months but had no effect at 12 months. The main conclusions of this thesis are: 1. TSA (anatomic and reverse) using stemless humeral components is reliable if bone quality is adequate. The complication rate is comparable with other shoulder prosthetic systems. 2. Glenoid overhang decreased complications in RSA. 3. LHO measurement on AP radiographs is less reliable and underestimates the distance when compared with CT. 4. Stemless TSA could be of help in reconstructing shoulder anatomy. 5. Shoulder reconstruction close to the anatomy of a healthy contralateral shoulder improves shoulder function. / Axelprotes kirurgi har visat avsevärd utveckling under de senaste decennierna. Ett antal faktorer påverkar postoperativt rörelseomfång, smärta och proteshållbarhet. Bland dessa faktorer utgör längden av hävarmen och ledstabilitet de faktorer som kan ändras genom val av proteskomponent. Det är osäkert om den normala anatomin måste återupprättas. Oskaftad protes med eliminering av humerusstamm och tillit till metafysär fixering introducerades i Frankrike år 2004 (TESS, Zimmer Biomet). Målen var att undvika stam relaterade komplikationer. Oskaftat implantat har andra potentiella fördelar, inklusive möjligheten att återställa axelnsanatomi. Syftet med denna avhandling var: (1) Att undersök radiologisk stabilitet av oskaftade axelproteser. (2) Att studera effekten av protes placering vid omvänd axelartroplastik både radiologiska och kliniskt utfall. (3) Att studera tillförlitlighet av mätningen av den laterala humeral offset (LHO), avståndet mellan processus coracoideus till laterala kanten av tuberkulum majus, med användning av CT eller röntgen. (4) Att studera oskaftad axelprotes förmåga att återställa axelnsanatomi. (5) Att studera den kliniska betydelsen av LHO återställning i för det funktionella resultatet efter axelartroplastik. Studie I: Detta är en prospektiv kohortstudie av 49 patienter med en av de två versionerna av TESS (anatomisk eller omvänd) med klinisk och radiologisk uppföljning från 9-24 månader. TESS protes visade lovande resultat på kort sikt med komplikationer som var jämförbar med andra axelprotessystem. Studie II: Detta är en prospektiv jämförande icke-randomiserad studie av 37 patienter (40 skuldror) som opererades med TESS omvänd axelartroplastik med en uppföljning från 15-66 månader. Vi fann en signifikant förbättring av funktion och minskning av smärta i både skaftad och oskaftad grupper. Glenoid overhang bedöms påverka risken för scapular notching (SN). Studie III: Detta är en radiologisk studie som visade att CT hade god tillförlitlighet och reproducerbarhet att mäta LHO. Studie IV: Detta är en prospektiv radiologisk studie av 69 patienter (70 skuldror) med primär artros som hade genomgått oskaftad total anatomisk axelprotes. Denna studie visade att oskaftad axelprotes kan vara till hjälp att återställa axelnsanatomi. Studie V: Detta är en prospektiv studie av 44 patienter med unilateral primär artros som hade genomgått oskaftad total axelprotes med en klinisk och radiologisk uppföljning från 12 - 50 månader. Vår studie visade att LHO rekonstruktion till den friska axeln förbättrar axelfunktion. Oskaftat implantat kan vara av hjälp till att återställa LHO. Ökad LHO kan ha en negativ effekt på axelnsfunktion vid tre månader, men denna effekt påvisade ej vid 12 månader. De viktigaste slutsatserna i denna avhandling är: 1. Oskaftad total axel artroplastik (anatomisk och omvänd) är tillförlitlig om benkvalitén är god med komplikationer som var jämförbar med andra axelprotessystem. 2. Glenoid overhang minskar komplikationer vid omvänd axelartroplastik. 3. LHO mätningen på röntgen är mindre tillförlitlig och underskattar avståndet jämfört med CT. 4. Oskaftad axelprotes skulle kunna vara till hjälp för att rekonstruera axelnsanatomi. 5. Axel rekonstruktion inom anatomi till att efterlikna anatomi på den friska kontralaterala axeln förbättrar axelfunktion.

Abstract Aim: The aim of this study was to investigate if treatment with “dry needling” in myofascial triggerpoints (MTrPs) in the rotatorcuff muscles may affect impingement symptoms such as pain during provocative tests, shoulder mobility, and function. The research questions were: Does the value of pain change on the Visual Analog Pain Scale (VAS) between before and after treatment? Do the positive provocative tests for impingement change between before and after treatment? Does the active shoulder mobility change between before and after treatment? Does the self-rated function change between before and after treatment? Method: The study was a prospective randomized intervention study and 19 persons with impingement symptoms (mean ± standard deviation; 58 ± 18 years, and shoulder pain duration 3.9 ± 1.6 months) were randomized into two groups. The groups were tested before, directly after and 3 weeks after treatment. The intervention group was treated twice, with a week in between, with “dry needling” in MTrPs. The control group was also treated on two occasions but was instead given a superficial needle in the infraspinatus muscle. All subjects were treated by the same physiotherapist. Pain was evaluated on the VAS when subjects performed active shoulder flexion before and after treatment. Provocative tests for shoulder impingement (Neer sign, Hawkins-Kennedy test and Jobe test) as well as range of motion tests were performed before, after and three weeks after treatment. The frequencies of positive/negative provocative tests were presented. Shoulder function was evaluated with the QuickDASH questionnaire. Significance level p≤0.05 was used in the study and a tendency was identified between 0.05 ≤ p &lt; 0.1. Results: There was a tendency (p=0.086) with decreased pain (VAS) in the intervention group after the treatment. Among the impingement tests only significant improved results was observed for Neer sign test three weeks after the treatment (p=0.025) No significant difference could be seen on the active shoulder mobility between before and after the treatment. The perceived function in the intervention group, measured with the Quick DASH questionnaire, showed a tendency (p=0.086) towards a better function. Conclusions: The study showed a tendency towards that”dry needling”  in MTrPs may affect impingement symptoms such as pain and function. The provocative tests for shoulder impingement, Neer sign, showed a significant decrease in pain after treatment. More studies with larger population is needed to make a statement about the effect of “dry needling” in MTrPs as a treatment for shoulder impingement symptoms. / Sammanfattning Syfte och frågeställningar: Syftet med studien var att undersöka om behandling med ”dry needling” (intramuskulär nålstimulering) i myofasciella triggerpunkter (MTrPs) i rotatorcuffmuskulaturen kan påverka impingementsymptom såsom smärta vid provokationstester, axelledsrörlighet och funktion. Frågeställningarna var: Förändras smärtskattning på visuell analog skala(VAS) vid aktiv axelflexion efter jämfört med före behandling? Förändras de positiva provokationstesterna för impingement efter jämfört med före behandling? Förändras den aktiva axelledsrörligheten efter jämfört med före behandling? Förändras den självskattade funktionen efter jämfört med före behandling? Metod: Studien var en prospektiv randomiserad interventionsstudie, 19 forskningspersoner (fp) med impingementsymptom, (medelålder 58 ± 18 år, besvärsdurationens medeltid 3.9 ± 1.6 mån), randomiserades till två grupper. Grupperna undersöktes före, direkt efter och tre veckor efter avslutad behandling. Interventionsgruppen behandlades vid två tillfällen, med en veckas mellanrum, med ”dry needling” i MTrPs medan kontrollgruppen vid två tillfällen istället fick en ytlig akupunkturnål i m infraspinatus. Behandlingen av alla fp utfördes av en och samma fysioterapeut. Smärta utvärderades med (VAS) vid aktiv axelflexion direkt före och efter behandling. Provokationstester (Neer sign, Hawkins-Kennedy test och Jobe test) samt rörlighetsmätning utfördes före, efter och tre veckor efter avslutad behandling. Frekvensen positiva/negativa provokationstesttest summerades. Funktionen utvärderades med frågeformuläret QuickDASH. Signifikansnivå p&lt; 0.05 används i studien och en tendens identifierades mellan 0.05 ≤ p &lt; 0.1. Resultat: Det fanns en tendens (p=0.086) till minskad smärta (VAS) i interventionsgruppen efter jämfört med före behandling. Bland impingementtesterna sågs enbart ett signifikant förbättrat resultat för Neers sign tre veckor efter avslutad behandling jämfört med före behandling (p=0.025). Ingen signifikant skillnad kunde ses gällande rörligheten före och efter behandling. Den upplevda funktionsförmågan mätt med frågeformuläret QuickDASH visade en tendens (p=0.086) mot bättre funktion i interventionsgruppen. Slutsats: Studien har visat tendenser på att ”dry needling” i MTrPs kan påverka impingementsymptom såsom minskad smärta och bättre självskattad funktion efter behandling jämfört med före. Impingementtestet Neer sign visade en signifikant minskad smärta efter behandling. Fler studier med större grupper, större ålderspann och längre behandlingstid behövs för att kunna uttala sig om effekten av ”dry needling” i MTrPs som behandlingsmetod vid impingementsymptom i axeln. / <p>Fristående kurs i Idrottsvetenskap inriktning idrottsmedicin 2013-2015</p>

Video streaming is widely recognized as the next Internet killer application. It was not one of the Internet's original target applications and its protocols (TCP in particular) were tuned mainly for e efficient bulk file transfer. As a result, a significant effort has focused on the development of UDP-based special protocols for streaming multimedia on the Internet. Recently, there has been a shift in video streaming from UDP to TCP, and specifically to HTTP. HTTP streaming provides a very attractive platform for video distribution on the Internet mainly because it can utilize all the current Internet infrastructure. In this thesis we make the argument that the marriage between HTTP streaming and the current Internet infrastructure can create many problems and inefficiencies. In order to solve these issues, we provide a set of techniques and protocols that can help both the network and end-hosts to make better decisions to improve video streaming quality. The thesis makes the following contributions: - We conduct a characterization study of popular commercial streaming services on mobile platforms. Our study shows that streaming services make different design decisions when implementing video players on different mobile platforms. We show that this can lead to several inefficiencies and undesirable behaviors specially when several clients compete for bandwidth in a shared bottleneck link. - Fairness between traffic flows has been preserved on the Internet through the use of TCP. However, due to the dynamics of adaptive video players and the lack of standard client adaptation techniques, fairness between multiple competing video flows is still an open issue of research. Our work extends the definition of standard bitrate fairness to utility fairness where utility is the Quality of Experience (QoE) of a video stream. We define QoE max-min fairness for a set of adaptive video flows competing for bandwidth in a network and we develop an algorithm that computes the set of bitrates that should be assigned to each stream to achieve fairness. We design and implement a system that can apply QoE fairness in home networks and evaluate the system on a real home router. - A well known problem that has been associated with TCP traffic is the buffer bloat problem. We use an experimental setup to show that adaptive video flows can cause buffer bloat which can significantly harm time sensitive applications sharing the same bottleneck link with video traffic. In addition, we develop a technique that can be used by video players to mitigate this problem. We implement our technique in a real video player and evaluate it on our testbed. - With the increasing popularity of video streaming on the Internet, the amounts of traffic on the peering links between video streaming providers and Internet Service Providers (ISPs) have become the source of many disputes. Hybrid CDN/P2P streaming systems can be used to reduce the amounts of traffic on the peering links by leveraging users upload bandwidth to redistribute some of the load to other peers. We develop an analysis for hybrid CDN/P2P systems that broadcast live adaptive video streams. The analysis helps the CDN to make better decisions to optimize video quality for its users.

Syfte och frågeställning Syftet med studien är att studera hur svenska elitlöpares totaltider förhåller sig till de olika variablerna markkontakt, flygtid, hastighet, stegfrekvens och steglängd, med största fokus på hur markkontakterna påverkar hastigheten. Studiens två frågeställningar var: (1) Hur ser sambandet ut mellan de fyra variablerna markkontakt, flygtid, steglängd samt stegfrekvens vid den maximala hastigheten vid upprätt löpning hos elitlöpare verksamma inom sprintdistansen 100 meter? (2) Hur korrelerar markkontakt och hastighet hos elitlöpare verksamma inom sprintdistansen 100 meter? Metod En kvantitativ studie genomfördes där 33 manliga och 20 kvinnliga försökslopp på flygande 30 kartlades med mätutrustningen Optojump. Dessa mätvärden analyserades i SPSS för att jämföra korrelation mellan varje mätvärde, ett sambandsdiagram mellan markkontakt och hastighet gjordes samt den översiktliga statistiken analyserades. Resultat Resultaten visar att kortare markkontakter kan ge en högre hastighet, att flygtiden mellan män och kvinnor är lika, att genomsnittet av löparna i studien hade än lägre stegfrekvens och steglängd än litteraturen som presenteras i studien. Slutsatser Resultatet i studien visar att, i likhet med forskningsstudier, att en kortare markkontakt kan ge en höge horisontell löphastighet än en lång. Studien åskådliggör dock att betydligt fler variabler, än endast markkontakt, har stor inverkan på hastighet och totaltid. Jämfört visar detta att mer forskning inom området behövs för att kunna optimera träningsupplägg för löpare. / Purpose and question The purpose of the study is to show how Swedish elit runners total times relate to the different variables ground contact, flight time, speed, step rate and step length, with the main focus on how the ground contacts time affect speed. The study's two main questions were: (1) What is the relationship between the four variables: ground contact, flight time, step length and the velocity at the maximum speed at upright running (2) How do the variable ground contact and velocity correlate between elite runners competing within the track and field event 100 meters? Method A quantitative study was conducted in which 33 male and 20 female runs attempts were mapped with the measuring equipment Optojump. These measured values were analyzed in SPSS to compare correlation between each measurement value, a scatterplot between ground contact and speed, and the summary statistics were taken out. Results The results show that shorter ground contacts times can provide a faster running velocity, that the flight time between men and women is equal, the average of the runners in the study have lower step rate and step length then the literature presented in the study. Conclusions The result of the study shows that, like research studies, a shorter ground contact time can provide a higher horizontal running speed than a longer ground contact. However, the study illustrates that significantly more variables, than only ground contact, have a major impact on velocity and total time. In comparison, this shows that more research in the field is needed to optimize training for runners.

Cette thèse porte sur la conception, la réalisation et la caractérisation de diodes lasers de puissance, faible bruit à 1.5 µm sur InP pour des applications d’optique hyperfréquence, notamment pour des liaisons optiques analogiques de grande dynamique pour les systèmes radar. La première partie du travail a consisté à modéliser et concevoir des structures laser DFB ayant de faibles pertes internes. Ces structures, appelées lasers à semelle, incorporent une couche épaisse de matériaux entre la zone active et le substrat pour agrandir et délocaliser le mode propre optique des zones dopées p. La complexité de la conception résidait dans le bon compromis à trouver entre les performances statiques et dynamiques. Nous avons réalisé des diodes-lasers DFB avec une puissance > 150 mW, un rendement de 0.4 W/A, un niveau de bruit de 160 dB/Hz et une bande passante de modulation à 3 dB de 7.5 GHz. Les composants ont ensuite été caractérisés puis évalués dans des liaisons analogiques. Nous avons démontré des performances de gain de liaison, de dynamique et de point de compression à l’état de l’art mondial. En bande L (1-2 GHz) par exemple, nous avons montré des liaisons avec 0.5 dB de gain, un point de compression de 21 dBm et une dynamique (SFDR) de 122 dB.Hz2/3.En utilisant la même méthodologie de conception, la dernière partie du travail de thèse a été consacrée à la réalisation et à la caractérisation de lasers de puissance à verrouillage de modes pour la génération de train d’impulsions ultra-courts et la génération de peignes de fréquences. Ces structures présentent de très faibles largeurs de raie RF (550 Hz) et de très fortes puissances optiques (> 18 W en puissance crête). / This work focuses on the design, realization and characterization of high power, low noise 1.5 µm diode lasers for microwave applications and more particularly for high dynamic optical analog link for radar systems. The first part of this study deals with modeling and design of low internal losses DFB laser structures. These specific structures are called slab-coupled optical waveguide lasers, and are composed of a thick layer between the active layer and the substrate. The aim of this waveguide is to enlarge the optical eigenmode and to move the optical mode away from p-doped layers. The main difficulty was to find the good trade-off between laser static performances (optical power, efficiency) and dynamic performances (RIN and modulation bandwidth). We have succeeded in developing high efficiency (0.4 W/A), low noise (RIN ≈ 160 dB/Hz) DFB lasers with more than 150 mW and a 3 dB modulation bandwidth up to 7.5 GHz. We have then characterized our components on wide band and narrow band analog links. We have demonstrated state of the art gain links, dynamic and 1 dB compression power. In the L band (1-2 GHz) for example, we have obtained an optical link with a gain of 0.5 dB, a compression power of 21 dBm and a dynamic (SFDR) of 122 dB.Hz2/3.Finally we have applied the methodology and the design of slab-coupled optical waveguide structures to develop high power mode-locked lasers for ultra-short pulses generation and for optical and electrical comb generation. We have demonstrated narrow RF linewidth (550 Hz) lasers with very high power (continuous power > 400 mW and peak power > 18 W).

Ce travail de thèse présente une étude sur les propriétés de nanostructures de type bâtonnets quantiques et de leur application pour les télécommunications optiques. Durant la dernière décennie, ces nanostructures, ont démontré des propriétés optiques et électroniques intéressantes en raison notamment d’un fort confinement quantique dans les trois dimensions d'espace. Cette thèse porte sur la conception et la fabrication d'émetteurs optiques intégrés à base de ce matériau et de leur implémentation dans des systèmes de communication. La première partie de ce travail analyse les propriétés de ces nanostructures, théorique et expérimentale. Elles sont utilisées comme matériau actif de lasers modulés directement en amplitude. Les propriétés dynamiques de ces lasers sont ensuite évaluées et des transmissions sur fibre optique entre 0 et 100 km sont ensuite démontrées en utilisant un filtre étalon permettant d’augmenter en particulier le taux d’extinction dynamique. En s’appuyant sur cette démonstration basée sur des éléments discrets, une version monolithique intégrant un laser et un résonateur en anneaux a été réalisée. La dernière partie de ce travail porte sur des lasers à blocage de mode à base de ce matériau et en particulier sur les méthodes d’intégration sur substrat InP. En particulier, un design de miroir de Bragg innovant a été développé à cet effet et une démonstration d'un laser a blocage de mode intégré avec un amplificateur optique à semi-conducteur a finalement été réalisée / This PhD dissertation presents a study on the properties of the novel quantum dash nanostructures and their properties for application in optical telecommunications. Over the last decade, scientific community has gained considerable interest over these nanostructures and several demonstrations have been made on their interesting optical and electronic properties, notably owing to their strong quantum confinement. This dissertation focuses on conception, fabrication and system demonstration of integrated optical transmitters based on quantum dash material. A first part of this work analyses the properties of qdashes theoretically and experimentally for their use as an active material in directly modulated lasers. The dynamic properties of this material are then evaluated leading to an optical transmission distances in range of 0-100km under direct modulation. The transmission is particularly studied with a passive optical filter to enhance the dynamic extinction ratio, the use of such passive filters is studied in detail. An innovative and fully integrated optical transmitter is finally demonstrated by integrating a ring-resonator filter to a distributed feedback laser. The second part of this work focuses on mode locked lasers based on this material and in particular the methods of integration of such devices on InP are explored. Thus an innovative Bragg mirror design is developed leading to a mode locked laser integrated with a semiconductor optical amplifier

Les peignes de longueurs d'onde, produisant des dizaines de porteuses optiques régulièrement espacées à partir d'une seule source laser, présentent un grand intérêt pour les systèmes de communication à haut débit. Ce travail de thèse porte sur les peignes générés par les diodes laser à blocage de modes basées sur des nanostructures semi-conductrices à basse dimensionnalité. Dans cette étude, les performances en verrouillage de modes de lasers Fabry-Pérot mono-section basés sur différents systèmes de matériaux sont comparées sur la base de la largeur du spectre optique d'émission et de la capacité à produire des impulsions courtes à faible gigue temporelle. En remarquant que les lasers à base de bâtonnets quantiques InAs sur InP présentent de meilleures caractéristiques par rapport aux autres matériaux examinés, leurs propriétés spécifiques en termes de stabilité des peignes de fréquences optiques et de chirp des impulsions sont étudiées plus en détail. Le chirp est d'abord étudié par la technique FROG (frequency-resolved optical gating). Ensuite, la dispersion chromatique du matériau laser est évaluée afin de vérifier si elle peut expliquer les grandes valeurs de chirp mesurées par FROG. Pour cela la technique de réflectométrie optique dans le domaine fréquentiel est utilisée et ses capacités uniques de mesure ont été étudiées et validées. Enfin, ces lasers sont employés avec succès pour les transmissions haut débit à l'aide de la technique de modulation optique OFDM (orthogonal frequency-division multiplexing) en détection directe. Débits de l'ordre du térabit par seconde, ainsi que le faible coût de l’architecture du système, sont très prometteurs pour les data centers / Optical frequency combs, generating tens of equally spaced optical carriers from a single laser source, are very attractive for next-generation wavelength division multiplexing (WDM) communication systems. This PhD thesis presents a study on the optical frequency combs generated by mode-locked laser diodes based on low-dimensional semiconductor nanostructures. In this work, the mode-locking performances of single-section Fabry-Pérot lasers based on different material systems are compared on the basis of the optical spectrum width, the timing jitter and pulse generation capabilities. Then, noticing that InAs quantum dashes grown on InP exhibit on average better characteristics than other examined materials, their unique properties in terms of comb stability and pulse chirp are studied in more detail. Laser chirp, in particular, is first investigated by frequency resolved optical gating (FROG) characterizations. Then, chromatic dispersion of the laser material is assessed in order to verify whether it can account for the large chirp values measured by FROG. For that, a high sensitivity optical frequency-domain reflectometry setup is used and its measurement capabilities are extensively studied and validated. Finally, the combs generated by quantum dash mode-locked lasers are successfully employed for high data rate transmissions using direct-detection optical orthogonal frequency division multiplexing. Terabit per second capacities, as well as the low cost of this system architecture, appear to be particularly promising for future datacom applications

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