Abstract
Fast semiconductor shutters based on coupled wells were designed in the search for reliable, compact and cheap key element of GHz repetition rate NIR lasers passive mode-locking. Stable 0.98 ...GHz repetition rate 200-fs Yb:KYW laser pulses were demonstrated for SESAM including semiconductor reflector and a layer of quantum wells. The damage threshold estimate for the SESAM is ∼ 8.87 mJ/cm
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. Other type of shutter – DSAM – was developed with dielectric reflector and the layer of quantum wells transferred over reflector. The measured recovery time was about 2-3 ps for both types of saturable absorbers. The efficiency relative to the incident pump power was 57% for the SESAM and 19% for the DSAM. Average output power of 2.54 W for the all-semiconductor shutter (SESAM) and of 0.92 W for the dielectric mirror with a saturable absorber (DSAM) were obtained. Actual state of the art for the shutters design is considered.
A stable passive mode-locking regime for a Yb3+ :KY(WO4)2 laser with optical pumping by a continuous diode laser was obtained using two types of optical shutter with a saturable absorber based on ...coupled GaAs/In0.25Ga0.75As/GaAs quantum wells. The shutters differed in their reflecting part: the first type was a semiconductor mirror and the second type was a dielectric one. The typical parameters of the mode-locking regime were as follows: a pulse duration of about 200 fs for both types of shutter, an average power of 2.54 W for the all-semiconductor shutter (SESAM) and 0.92 W for the dielectric mirror with a saturable absorber (DSAM). The efficiency relative to the incident pump power was 57% for the SESAM and 19% for the DSAM. The maximum pulse repetition rate was 982 MHz. The measured recovery time was about 2 ps for both saturable absorbers. The mirror damage threshold estimate for the SESAM was at least 8.87 mJ cm−2.
The primary objective of the present study was to estimate the effectiveness of the new methods of physical rehabilitation for mountain ski athletes designed to optimize and accelerate restoration of ...their professional capabilities after arthroscopic plastic reconstruction of anterior cruciate ligament (ACL). This open controlled prospective study involved 26 alpine skiers aged from 18 to 25 who were recruited into the regular follow up program based at our Centre during the last 3 years. The athletes proved able to start balance training on the Biodex platform 4 weeks earlier than with the use of the conventional approach. These exercises were supplemented by the training of speed endurance on the Speed Courte tensor platform and Sky Teck ski simulators. Control studies were carried out on the 16th and 24th weeks of the rehabilitation period. Their results were compared with the results shown by the same athletes before injury. It was found that the early introduction of exercises designed to normalize proprioception into the rehabilitative treatment allowed the injured mountain ski athletes to restore the strength of femoral muscles and specific professional skills by the 4th month of the rehabilitation period. It is concluded that the combination of classical rehabilitative techniques with balance training, Speed Court training, and training on the alpine ski simulator makes it possible to begin special of alpine ski training on the snow 2 months earlier than with the use of conventkional methods.
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