Miniaturizing a coherent beam combining system into a compact laser diode module.

We present a laser module with dimensions of 76×43×15m m 3 that for the first time to our knowledge realizes a coherent beam combination in such a compact device, using two tapered amplifiers seeded by a distributed Bragg reflector ridge waveguide laser diode operating at 761 nm in a single longitudinal mode. The generated combined optical power is up to 5 W continuous wave with a combing efficiency of 85%. The phase of the system is controlled by the current in the ridge waveguide section of one of the tapered amplifiers. The phase-stabilization process is automated using a reverse hill-climbing algorithm and an ATmega328P microcontroller.

UV generation via periodically poled MgO:LiTaO3 circular waveguide crystal and diode-based master oscillator power amplifier.

Lasers with emission wavelengths in the near-ultraviolet (UV) spectral range have been used in many applications across various fields, and the demand for these lasers has been on the rise. For example, in medicine, near-UV light has been used for fluorophore excitation. Although laser diodes emitting in this region exist, single longitudinal mode lasers emitting at 380 nm with high optical power are limited. One of the solutions to this problem is the use of second harmonic generation by a non-linear crystal. In this work, single-longitudinal-mode laser emission at 380.5 nm with an optical power of up to 13 mW has been achieved. The emission was realized by frequency doubling using a periodically poled circular waveguide crystal of stoichiometric L i T a O 3 doped with MgO (PPMgSLT) pumped by a master oscillator power amplifier with optical power up to 5 W. A distributed Bragg reflector ridge waveguide laser diode at 761 nm was used as the master oscillator and a tapered amplifier as the power amplifier.

Recovery Kinetics Following Small-Sided Games in Competitive Soccer Players: Does Player Density Size Matter?

PURPOSE: To examine the recovery kinetics of exercise-induced muscle damage (EIMD), neuromuscular fatigue, and performance following small-sided games (SSGs) of different densities in soccer. METHODS: Ten male players randomly completed 3 trials: a control trial (no SSGs), 4v4 SSGs (62.5 m2/player), and 8v8 SSGs (284.4 m2/player). External and internal load were monitored using GPS technology, heart-rate monitors, and rating of perceived exertion. Delayed-onset muscle soreness (DOMS), creatine kinase (CK), isokinetic strength, countermovement jump (CMJ), and sprint were determined at baseline, as well as at 24, 48, and 72 hours post-SSGs. Neuromuscular fatigue was assessed at baseline and at 1, 2, and 3 hours post-SSGs. RESULTS: DOMS increased (P < .05) in 4v4 for 72 hours and in 8v8 for 24 hours with that of knee flexors being more pronounced than that of extensors. CK increased (P < .05) in 4v4 for 72 hours and in 8v8 for 24 hours. Neuromuscular fatigue increased (P < .05) in 4v4 for 2 hours and in 8v8 for 3 hours. Strength declined (P < .05) in 4v4 for 48 hours and in 8v8 for 72 hours. CMJ decreased (P < .05) in 4v4 for 24 hours and in 8v8 for 48 hours. Sprint decreased (P < .05) for 48 hours in 4v4 and for 72 hours in 8v8. CONCLUSIONS: SSGs are associated with a prolonged rise of EIMD and induce short-term neuromuscular fatigue and slow recovery kinetics of strength, jump, and sprinting performance. The time for complete recovery is longer for SSGs of lower density.

Injury prevalence and risk factors in a Greek team's professional football (soccer) players: a three consecutive seasons survey.

This study investigated the prevalence and risk factors of injuries on a cohort of 123 Greek team's professional football players during three consecutive seasons, 2015/16-to-2017/18. Injuries were assessed and regression analysis was used to evaluate the potential risk factors. Three-quarters of the players were recorded as injured with 2.3 injuries/injured player, and the injury incidence was 55 injuries/1,000 match-playing-exposure-hours. The mean rehabilitation days were 29.3/injured player (95%CI 22.4-36.8) and 13.0/injury (95%CI 8.6-17.4). The majority of injured players has been found to have moderate-to-major/severe injuries and most of the injuries were traumatic than overuse (p < 0.05). The number of injuries were related to the recurrence of injury (beta = 0.646, p < 0.001) and the rehabilitations days (beta = 0.271, p < 0.001). High prevalence of injuries was found as the recurrence of injury and rehabilitation days were their main predictive risk factors. In order to reduce the risk of injuries, continuous effort is required in the rehabilitation of players.