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1.
Eur Arch Paediatr Dent ; 20(3): 277-284, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30879261

RESUMO

AIM: To improve the oral health of children and teenagers with autism spectrum disorder (ASD) by using an iPad®-based training programme. METHODS: Fifty-two children and teenagers with ASD (aged 3-19 years) educated in schools or in care centres participated in this cohort study and followed for 8 months. A training programme for teaching toothbrushing behaviours was proposed to the educational staff. Quotation grids enabled assessment of the programme's efficacy. RESULTS: Showed an improvement in toothbrushing. The children's autonomy increased and oral care was more easily implemented when steps were taken by the caregivers. Wilcoxon analysis showed significant improvement in each variable related to toothbrushing. CONCLUSIONS: The iPad® is an attractive and easy device for people with ASD to use. Its use in a training programme for teaching toothbrushing behaviours was efficient.


Assuntos
Transtorno do Espectro Autista , Transtorno Autístico , Adolescente , Adulto , Criança , Pré-Escolar , Estudos de Coortes , Humanos , Saúde Bucal , Escovação Dentária , Adulto Jovem
2.
Eur Arch Paediatr Dent ; 20(2): 113-121, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30542908

RESUMO

AIM: To present a training programme for teaching children and adolescents with autism spectrum disorder (ASD), to be compliant with a dental examination. METHODS: Fifty-two children and adolescents with ASD (age range 3-19 years) with a parent-signed consent form were enrolled. Dental examinations were performed once a month in education centres by a paediatric dentist using a visual activity schedule on an iPad® that was created with a digital application, çATED. Achievement and anxiety were evaluated using scales and grids every 2 months for 8 months. RESULTS: Showed an improvement in oral assessment; the children became compliant and less anxious. The percentage of individuals who underwent the entire dental exam process increased over time; it was 25% at the beginning of the study and 65.4% after 8 months. Only 7.7% of the sample was not anxious at the beginning, while 59.6% of the sample was not anxious after 8 months. Wilcoxon analysis also showed significant improvement in the studied variables. CONCLUSIONS: Training children and adolescents with ASD to undergo dental examination was efficient. The use of the iPad® is attractive and easy for practitioners and people with ASD.


Assuntos
Transtorno do Espectro Autista , Ansiedade ao Tratamento Odontológico , Adolescente , Adulto , Ansiedade , Criança , Pré-Escolar , Ansiedade ao Tratamento Odontológico/prevenção & controle , Assistência Odontológica , Humanos , Pais , Adulto Jovem
3.
Rev Epidemiol Sante Publique ; 66(2): 107-116, 2018 Mar.
Artigo em Francês | MEDLINE | ID: mdl-29530440

RESUMO

BACKGROUND: The oral diseases of people with disabilities are the same as those observed in the general population but occur earlier and more intensely. Primary prevention, especially toothbrushing, is at the forefront of the appropriate management of these patients. The aim of this study is to evaluate the use of a digital application on iPad® as mediator for learning toothbrushing in children with disabilities. METHODS: Twelve children from a care-center were included in this preliminary study. A training program for toothbrushing was conducted, using a visual activity schedule on iPad®. Quotation grids enabled to assess the initial situation and the program efficacy over an 11-month period. RESULTS: The children progressed over time in their autonomy and in their compliance during toothbrushing. Wilcoxon's analysis showed that these progresses were significant, although some steps remained more difficult to achieve. Three months after the end of the program, the children maintained their skills. CONCLUSIONS: The integration of the iPad® as a support for visual pedagogy and learning is useful in a dental context, for children with cognitive disabilities.


Assuntos
Recursos Audiovisuais , Transtornos Cognitivos , Computadores de Mão , Crianças com Deficiência/educação , Saúde Bucal/educação , Educação de Pacientes como Assunto/métodos , Escovação Dentária , Criança , Transtornos Cognitivos/psicologia , Crianças com Deficiência/psicologia , Feminino , França , Humanos , Masculino , Doenças da Boca/prevenção & controle , Cooperação do Paciente , Projetos Piloto , Prevenção Primária/métodos , Escovação Dentária/métodos , Escovação Dentária/normas , Tato
4.
Biol Sport ; 33(1): 23-8, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26985130

RESUMO

Leptin and adiponectin play an essential role in energy metabolism. Leptin has also been proposed as a marker for monitoring training load. So far, no studies have investigated the variability of these hormones in athletes and how they are regulated during cumulative exercise. This study monitored leptin and adiponectin in 15 endurance athletes twice daily in the days before, during and after a 9-day simulated cycling stage race. Adiponectin significantly increased during the race (p = 0.001) and recovery periods (p = 0.002) when compared to the baseline, while leptin decreased significantly during the race (p < 0.0001) and returned to baseline levels during the recovery period. Intra-individual variability was substantially lower than inter-individual variability for both hormones (leptin 34.1 vs. 53.5%, adiponectin 19% vs. 37.2%). With regards to exercise, this study demonstrated that with sufficient, sustained energy expenditure, leptin concentrations can decrease within the first 24 hours. Under the investigated conditions there also appears to be an optimal leptin concentration which ensures stable energy homeostasis, as there was no significant decrease over the subsequent race days. In healthy endurance athletes the recovery of leptin takes 48-72 hours and may even show a supercompensation-like effect. For adiponectin, significant increases were observed within 5 days of commencing racing, with these elevated values failing to return to baseline levels after 3 days of recovery. Additionally, when using leptin and adiponectin to monitor training loads, establishing individual threshold values improves their sensitivity.

5.
Opt Lett ; 40(6): 1030-3, 2015 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-25768174

RESUMO

We report on a coherent wind lidar built with two coherently-beam-combined fiber amplifiers. The lidar performances of the combined-amplifier and the single-amplifier are compared using two criterions: carrier-to-noise ratio and wind speed noise floor. In both cases, lidar performances are not degraded with a combined source and are close to the theoretical optimum. Combined sources are well suited to improve coherent wind lidar accuracy, range, and integration time.

6.
Appl Opt ; 53(8): 1493-502, 2014 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-24663405

RESUMO

We introduce orthogonally coded modulations for active coherent beam combining (CBC), and show how using Walsh codes enables the increase of the number of combined channels. Analytical, numerical, and experimental results are presented and compared to the standard multifrequency dithering technique, demonstrating that at least 5 times more fibers can be combined using the same modulation frequency. The modulation format excluded, no particular changes in the system need to be introduced and the benefits of active coherent beam combing, such as atmospheric turbulence compensation capability, are kept unchanged. Finally, we point out that this approach can be applied in partially CBC.

7.
J Sports Med Phys Fitness ; 54(2): 179-85, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24509989

RESUMO

AIM: Hematological and biochemical parameters of 160 Middle Eastern adolescent male athletes (aged from 12-18 years) were tested in order to investigate their iron status and to establish reference values for this population. A focus of this study was also the investigation of Reticulocyte hemoglobin (RetHe) and soluble transferrin receptor (sTfR). METHODS: Complete blood count, reticulocyte and sera parameters were analyzed at the beginning of the training season for these adolescent athletes. As the diagnosis of iron deficiency in adolescents is extremely difficult subjects were subdivided in three age groups (12-13, 14-15, 16-18). RESULTS: For most of the parameters our results confirmed the existing reference values reported in young athletes. Exceptions were however found with lower Mean Cell Volumes (79.9±4.3 fl) in this group when compared to other age matched data. RetHe, ferritin and sTfR levels were monitored for the interpretation of the iron status in this population and reference values for these parameters were also established. CONCLUSIONS: Information to help evidence based decision making about the need for supplementation or further investigations is provided to physicians and nutritionists. RetHe with a proposed threshold value of 25 pg expands the list of parameters which can be used to monitor athletes.


Assuntos
Atletas , Hemoglobinas/metabolismo , Ferro/sangue , Receptores da Transferrina/sangue , Reticulócitos/metabolismo , Adolescente , Contagem de Células Sanguíneas , Criança , Humanos , Masculino , Catar , Valores de Referência
8.
Int J Sports Med ; 35(2): 89-94, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23868682

RESUMO

The athlete biological passport for the fight against doping is currently based on longitudinal monitoring for abnormal changes in cellular blood parameters. Serum parameters related to altered erythropoiesis could be considered for inclusion in the passport. The aim of this study was to quantify the changes in such parameters in athletes during a period of intense exercise.12 highly trained cyclists tapered for 3 days before 6 days of simulated intense stage racing. Morning and afternoon blood samples were taken on most days and analysed for total protein, albumin, soluble transferrin receptor and ferritin concentrations. Plasma volume was determined via total haemoglobin mass measured by carbon-monoxide rebreathing. Percent changes in means from baseline and percent standard errors of measurement (analytical error plus intra-athlete variation) on each measurement occasion were estimated with mixed linear modelling of log-transformed measures. Means of all variables changed substantially in the days following the onset of racing, ranging from -13% (haemoglobin concentration) to +27% (ferritin). After the second day, errors of measurement were generally twice those at baseline. Plasma variables were affected by heavy exercise, either because of changes in plasma volume (total protein, albumin, haemoglobin), acute phase/inflammatory reactions (ferritin) or both (soluble transferrin receptor). These effects need to be taken into consideration when integrating a plasma parameter into the biological passport model for athletes.


Assuntos
Ciclismo/fisiologia , Proteínas Sanguíneas/metabolismo , Comportamento Competitivo , Eritropoese/fisiologia , Volume Plasmático , Adulto , Comportamento Competitivo/fisiologia , Dopagem Esportivo , Ferritinas/sangue , Hemoglobinas/metabolismo , Humanos , Masculino , Receptores da Transferrina , Albumina Sérica/metabolismo , Adulto Jovem
9.
Br J Sports Med ; 47 Suppl 1: i59-69, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24282209

RESUMO

OBJECTIVES: To examine with a parallel group study design the performance and physiological responses to a 14-day off-season 'live high-train low in the heat' training camp in elite football players. METHODS: Seventeen professional Australian Rules Football players participated in outdoor football-specific skills (32 ± 1°C, 11.5 h) and indoor strength (23 ± 1°C, 9.3 h) sessions and slept (12 nights) and cycled indoors (4.3 h) in either normal air (NORM, n=8) or normobaric hypoxia (14 ± 1 h/day, FiO2 15.2-14.3%, corresponding to a simulated altitude of 2500-3000 m, hypoxic (HYP), n=9). They completed the Yo-Yo Intermittent Recovery level 2 (Yo-YoIR2) in temperate conditions (23 ± 1°C, normal air) precamp (Pre) and postcamp (Post). Plasma volume (PV) and haemoglobin mass (Hb(mass)) were measured at similar times and 4 weeks postcamp (4WPost). Sweat sodium concentration ((Na(+))(sweat)) was measured Pre and Post during a heat-response test (44°C). RESULTS: Both groups showed very large improvements in Yo-YoIR2 at Post (+44%; 90% CL 38, 50), with no between-group differences in the changes (-1%; -9, 9). Postcamp, large changes in PV (+5.6%; -1.8, 5.6) and (Na(+))sweat (-29%; -37, -19) were observed in both groups, while Hb(mass) only moderately increased in HYP (+2.6%; 0.5, 4.5). At 4WPost, there was a likely slightly greater increase in Hb(mass) (+4.6%; 0.0, 9.3) and PV (+6%; -5, 18, unclear) in HYP than in NORM. CONCLUSIONS: The combination of heat and hypoxic exposure during sleep/training might offer a promising 'conditioning cocktail' in team sports.


Assuntos
Altitude , Futebol Americano/fisiologia , Aclimatação/fisiologia , Desempenho Atlético/fisiologia , Pressão Atmosférica , Austrália , Volume Sanguíneo/fisiologia , Exercício Físico/fisiologia , Hemoglobinas/metabolismo , Temperatura Alta , Humanos , Hipóxia/fisiopatologia , Corrida/fisiologia , Sono/fisiologia
10.
Growth Horm IGF Res ; 23(4): 105-8, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23608056

RESUMO

OBJECTIVE: The major objective of this study was to investigate the effects of several days of intense exercise on growth hormone (hGH) testing using the World Anti-Doping Agencies hGH isoform differential immunoassays. Additionally the effects of circadian variation and exercise type on the isoform ratios were also investigated. STUDY DESIGN: 15 male athletes performed a simulated nine day cycling stage race. Blood samples were collected twice daily over a period of 15 days (stage race+three days before and after). hGH isoforms were analysed by the official WADA immunoassays (CMZ Assay GmbH). RESULTS: All measured isoform ratios were far below the WADA decision limits for an adverse analytical finding. Changes in the isoform ratios could not be clearly connected to circadian variation, exercise duration or intensity. CONCLUSIONS: The present study demonstrates that the hGH isoform ratios are not significantly affected by exercise or circadian variation. We demonstrated that heavy, long term exercise does not interfere with the decision limits for an adverse analytical finding.


Assuntos
Dopagem Esportivo , Exercício Físico/fisiologia , Hormônio do Crescimento Humano/sangue , Detecção do Abuso de Substâncias/métodos , Adulto , Hormônio do Crescimento Humano/administração & dosagem , Humanos , Imunoensaio , Masculino , Isoformas de Proteínas , Fatores de Tempo
11.
J Sci Med Sport ; 16(6): 550-5, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23332540

RESUMO

OBJECTIVES: To examine the usefulness of selected physiological and perceptual measures to monitor fitness, fatigue and running performance during a pre-season, 2-week training camp in eighteen professional Australian Rules Football players (21.9±2.0 years). DESIGN: Observational. METHODS: Training load, perceived ratings of wellness (e.g., fatigue, sleep quality) and salivary cortisol were collected daily. Submaximal exercise heart rate (HRex) and a vagal-related heart rate variability index (LnSD1) were also collected at the start of each training session. Yo-Yo Intermittent Recovery level 2 test (Yo-YoIR2, assessed pre-, mid- and post-camp, temperate conditions) and high-speed running distance during standardized drills (HSR, >14.4 km h(-1), 4 times throughout, outdoor) were used as performance measures. RESULTS: There were significant (P<0.001 for all) day-to-day variations in training load (coefficient of variation, CV: 66%), wellness measures (6-18%), HRex (3.3%), LnSD1 (19.0%), but not cortisol (20.0%, P=0.60). While the overall wellness (+0.06, 90% CL (-0.14; 0.02) AU day(-1)) did not change substantially throughout the camp, HRex decreased (-0.51 (-0.58; -0.45)% day(-1)), and cortisol (+0.31 (0.06; 0.57) nmol L(-1)day(-1)), LnSD1 (+0.1 (0.04; 0.06) ms day(-1)), Yo-YoIR2 performance (+23.7 (20.8; 26.6) m day(-1), P<0.001), and HSR (+4.1 (1.5; 6.6) m day(-1), P<0.001) increased. Day-to-day ΔHRex (r=0.80, 90% CL (0.75; 0.85)), ΔLnSD1 (0.51 (r=0.40; 0.62)) and all wellness measures (0.28 (-0.39; -0.17)

Assuntos
Futebol Americano/fisiologia , Condicionamento Físico Humano , Fadiga/psicologia , Futebol Americano/psicologia , Humanos , Masculino , Psicometria , Corrida/fisiologia , Adulto Jovem
12.
Int J Sports Med ; 34(2): 101-10, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22960988

RESUMO

The purpose of this study was to quantify match play intensity distribution in young soccer players in relation to age, playing position and physical fitness. Distance covered and heart rate were measured (global positioning system) on 103, highly-trained young players (Under13 to Under 18) during 42 international club games. Maximal sprinting speed (MSS), estimated maximal aerobic speed (MAS) and maximal heart rate (HRmax) were assessed via field test measures. Distance covered and heart rate (HR) were categorized into 5 intensity zones relative to MSS and MAS and HR(max), respectively. Intensity distribution was significantly influenced by both age and playing position with younger groups, wide-midfielders and strikers covering the greatest distance above the MAS. There was a significant, negative, large-to-very large correlation (r= -0.52-0.74) between MAS and the distance run at speeds above MAS for all positions except strikers. HR responses were not different across age groups and playing positions. Distance covered below MAS were lower in the second half for all positions (P<0.05; 0.08<η(2)<0.20), while distance covered at intensities above MAS were maintained (P>0.1; 0.00<η(2)<0.03). This reduction in distance covered below MAS was not related to a player's physical capacity. Except for strikers, a superior aerobic fitness level was unlikely to affect total distance covered but was associated with a reduced individual running demand during the game.


Assuntos
Desempenho Atlético/fisiologia , Esforço Físico/fisiologia , Aptidão Física/fisiologia , Futebol/fisiologia , Adolescente , Fatores Etários , Análise de Variância , Criança , Sistemas de Informação Geográfica , Frequência Cardíaca , Humanos , Corrida/fisiologia , Estudos de Tempo e Movimento
13.
Int J Lab Hematol ; 34(6): 641-7, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22805050

RESUMO

INTRODUCTION: Dehydration, fluid shifts or changes in coagulation occurring during air travel can trigger distinct reactions in the haematological system. Athletes are concerned that these effects might impair sporting performance, increase the risk of thrombosis or cause abnormalities in blood values that might be mistaken for doping in the 'Athlete's biological passport' (ABP) a longitudinal monitoring of haematological variables in antidoping. The aim of the study was to investigate key variables of the ABP before and after a long-haul flight in athletes. METHODS: Fifteen endurance athletes were submitted to ABP blood samples in the morning before and after arrival of an 8 h flight. Two additional samples were obtained in the morning and the evening 3 days after the travel. Twelve nontravelling subjects served as controls. RESULTS: Haemoglobin concentration was higher before than after travel in athletes (+0.5 g/dL, P = 0.038), a similar pattern was observed 3 days after the travel. No difference was observed in the control group. Reticulocyte% did not show any significant changes in neither of the groups. CONCLUSION: The observed changes are in line with normal diurnal variations. There is no indication that travel will affect haematological variables in way that might be mistaken for blood doping.


Assuntos
Viagem Aérea , Atletas , Biomarcadores/sangue , Medicina Esportiva/métodos , Adulto , Ritmo Circadiano , Testes Hematológicos/métodos , Hemoglobinas/análise , Humanos , Contagem de Reticulócitos , Fatores de Tempo , Adulto Jovem
14.
Opt Lett ; 37(4): 650-2, 2012 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-22344136

RESUMO

We experimentally investigate the impact of spectral phase mismatch on the coherent beam combining of two femtosecond fiber chirped-pulse amplifiers. By measuring the differential spectral phase, both linear and nonlinear contributions are identified. An accumulated nonlinear phase as high as 6 rad has been measured, for which a combination efficiency of 91% can be obtained by symmetrizing the pump and injection powers. This also allows us to quantitatively separate the spatial and temporal contributions of the nonperfect combining efficiency.

15.
Int J Sports Med ; 33(4): 253-7, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22318561

RESUMO

Haemoglobin mass (Hbmass) determination using CO rebreathing may assist to detect illegal blood doping practices, however variations in Hbmass with periods of intensive training and detraining must be quantified. This study aimed to determine the effect of a 30-day period of detraining on Hbmass in ultra-endurance triathletes. 9 male recreational triathletes (29-44 years) participated in the study. Hbmass was assessed using CO rebreathing 30 days and 10 days before an ultra-endurance triathlon and after ~10, 20 and 30 days of detraining following the race. V˙O2max was assessed 10 days before the race and also after the 30-day detraining period, which consisted of an 87% reduction in training hours. After 30-days of detraining there was a 3.1% decrease in mean Hbmass from 868±99 to 840±94 g, (p=0.03), and a 4.7% decrease in mean V˙O2max from 4.83±0.29 to 4.61±0.41 L/min as well as a 2.8% increase of body mass from 75.1±6.4 to 77.1±6.1 kg and a 28% increase in skinfold total from 43.9±14.2 to 55.1±14.0 mm. Individual decreases in Hbmass following detraining would need to be considered if using Hbmass for anti-doping purposes.


Assuntos
Ciclismo/fisiologia , Hemoglobinas/fisiologia , Consumo de Oxigênio/fisiologia , Educação Física e Treinamento , Corrida/fisiologia , Natação/fisiologia , Adulto , Volume Sanguíneo , Carboxihemoglobina/análise , Dopagem Esportivo/prevenção & controle , Humanos , Masculino , Resistência Física/fisiologia , Fatores de Tempo
16.
Eur J Appl Physiol ; 112(2): 711-23, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21656232

RESUMO

The aim of the present study was to verify the validity of using exercise heart rate (HRex), HR recovery (HRR) and post-exercise HR variability (HRV) during and after a submaximal running test to predict changes in physical performance over an entire competitive season in highly trained young soccer players. Sixty-five complete data sets were analyzed comparing two consecutive testing sessions (3-4 months apart) collected on 46 players (age 15.1 ± 1.5 years). Physical performance tests included a 5-min run at 9 km h(-1) followed by a seated 5-min recovery period to measure HRex, HRR and HRV, a counter movement jump, acceleration and maximal sprinting speed obtained during a 40-m sprint with 10-m splits, repeated-sprint performance and an incremental running test to estimate maximal cardiorespiratory function (end test velocity V (Vam-Eval)). Possible changes in physical performance were examined for the players presenting a substantial change in HR measures over two consecutive testing sessions (greater than 3, 13 and 10% for HRex, HRR and HRV, respectively). A decrease in HRex or increase in HRV was associated with likely improvements in V (Vam-Eval); opposite changes led to unclear changes in V (Vam-Eval). Moderate relationships were also found between individual changes in HRR and sprint [r = 0.39, 90% CL (0.07;0.64)] and repeated-sprint performance [r = -0.38 (-0.05;-0.64)]. To conclude, while monitoring HRex and HRV was effective in tracking improvements in V (Vam-Eval), changes in HRR were moderately associated with changes in (repeated-)sprint performance. The present data also question the use of HRex and HRV as systematic markers of physical performance decrements in youth soccer players.


Assuntos
Desempenho Atlético/fisiologia , Frequência Cardíaca/fisiologia , Monitorização Ambulatorial/métodos , Aptidão Física/fisiologia , Futebol/fisiologia , Análise e Desempenho de Tarefas , Adolescente , Humanos , Masculino
17.
Scand J Med Sci Sports ; 22(6): 722-8, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21477205

RESUMO

A high hemoglobin mass (Hb(mass)) is associated with a high maximum aerobic power (VO(2max)), however, the extent to which Hb(mass) is influenced by training is currently unclear. Accordingly, this study monitored changes in Hb(mass) and VO(2max) in 12 previously untrained adults (aged 18-25 years) following 40 days of regular physical activity. Hb(mass) and VO(2max) were assessed at the start and end of a 40-day physical activity program, which comprised of approximately 40 min of daily, moderate-intensity physical activity. Relative VO(2max) increased by 11.3%, yet there was no significant change in relative Hb(mass) (1.7%) and body mass (0.2%) during the 40-day period. There was a significant correlation between Hb(mass) and VO(2max) at the start of the study (r=0.58, P=0.05), but not between the change in relative VO(2max) and the change in relative Hb(mass) (r=-0.07, P=0.83). Our results support the concept of relative stability in Hb(mass) with approximately 1 month of moderate-intensity physical activity suggesting that Hb(mass) may be used for talent identification and possibly for anti-doping purposes.


Assuntos
Exercício Físico/fisiologia , Hemoglobinas/metabolismo , Consumo de Oxigênio/fisiologia , Adolescente , Adulto , Volume Sanguíneo , Dopagem Esportivo/prevenção & controle , Feminino , Humanos , Masculino , Adulto Jovem
18.
Opt Lett ; 36(15): 2859-61, 2011 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-21808338

RESUMO

Cascaded Raman wavelength shifting up to the fourth order ranging from 2092 to 2450 nm is demonstrated using a nanosecond pump at 1995 nm in a low-loss As(38)Se(62) suspended-core microstructured fiber. These four Stokes shifts are obtained with a low peak power of 11 W, and only 3 W are required to obtain three shifts. The Raman gain coefficient for the fiber is estimated to (1.6±0.5)×10(-11) m/W at 1995 nm. The positions and the amplitudes of the Raman peaks are well reproduced by the numerical simulations of the nonlinear propagation.

19.
Opt Lett ; 36(5): 621-3, 2011 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-21368927

RESUMO

We demonstrate coherent beam combining of two femtosecond fiber chirped-pulse amplifiers seeded by a common oscillator. Using a feedback loop based on an electro-optic phase modulator, an average power of 7.2 W before compression is obtained with a combining efficiency of 90%. The spatial and temporal qualities of the oscillator are retained, with a recombined pulse width of 325 fs. This experiment opens up a way to scale the peak/average power of ultrafast fiber sources.

20.
Opt Lett ; 36(4): 523-5, 2011 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-21326443

RESUMO

We report what we believe to be the first experimental demonstration of coherent beam combining of two fiber amplifiers in a 100 ns pulse regime using a signal leak between the pulses. Pulses of ∼100 W stimulated-Brillouin-scattering limited peak power are combined with 95% efficiency, a residual phase error of λ/27, and no significant beam quality degradation.

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