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Single-pass and double-pass pre-chip managed (PCMA) fiber amplifier systems were designed and constructed for amplification of femtosecond pulses from Yb:KGW oscillator „Flint“. Spatial, temporal and power characteristics of amplified light was measured. A PCMA fiber amplifier was demonstrated for the first time, in which pulse pre-chirping and pulse compression is done using Gires – Tournois interferometric (GTI) mirror pairs. Such a combination of GTI’s and PCMA allowed to achieve 75 fs almost transform limited amplified pulses with average power of 19 W. Moreover, the use of GTI mirrors in the PCMA system is attractive due to its easy adjustment, high energy efficiency (>93%) and compactness. Also, the features of PCMA nonlinear amplification method were determined – broadened spectrum of amplified pulses due to self-phase modulation and optimal pre-chirping group delay dispersion at which the highest quality shortest pulses were determined. In addition, a double-pass PCMA amplification system has been demonstrated for the first time, which not only retains the advantages of the single-pass PCMA method but has an even higher gain and efficiency. Such a PCMA amplifier will be used as a high power and high pulse quality laser system for further nonlinear optics experiments.

Pakistaną bei Afganistaną skirianti Durand linija yra pati pavojingiausia šių valstybių pasienio riba. Kabulas niekada nepripažino šios linijos kaip tarptautinės tarpvalstybinės sienos tvirtindamas, kad puštūnų teritorijos Pakistane – FATA (Federally Administered Tribal Areas) ir dalis NWFP (North West Frontier Province) yra neteisėtai atskirtos nuo Afganistano. Teroristinio smurto banga Pakistano – Afganistano pasienio ruože pastebimai augo nuo Talibano režimo nuvertimo Kabule 2001 m. Dalyje pasienio teritorijos įsitvirtino džihadistų grupuotės bei teroristinių tinklų vadai. Paskutiniuosius keletą metų Jungtinių Amerikos Valstijų žvalgybos tarnybų ataskaitose vis didesnis dėmesys skiriamas Pakistano – Afganistano pasienio regione atgimstančiam ir stiprėjančiam Talibanui bei stiprėjančiai al-Qaeda grupuotei. Vašingtono bei NATO strategams darosi akivaizdu, kad norint laimėti karą Afganistane, negalima ignoruoti chaoso Pakistano gentinėse teritorijose. Pakistan and Afghanistan share border – Durand Line, it remains the most dangerous portion of both countries international borders. Kabul has never recognized the line as an international border, instead claiming that Pashtun territories in Pakistan that comprise the Federally Administered Tribal Areas (FATA) and parts of North West Frontier Province along the border, were illegally separated from Afghanistan. The Afghan government insists Pakistan increase security and stop incursions by Taliban insurgents into country. As the tribal lands continue to serve as a training base for terrorists and the Taliban, deploying Pakistani troops into the region has harmed efforts to integrate the tribal areas into Pakistan. The wave of militant violence have increased on both sides of the Pakistan-Afghanistan border since 2001, when a US-led military coalition invaded Afghanistan and the Taliban regime collapsed. In the last several years, United States intelligence reports have repeatedly attributed the growing strength and resurgence of Taliban and al- Qaeda to safe havens in this border region. There is growing consensus in Washington and NATO headquarters that to win the war in Afghanistan, it had to address the chaos in Pakistan’s tribal areas. Pakistan’s civilian politicians are not strong enough to accept U.S. demands if it means contradicting the army’s policies. Pakistan’s premier intelligence service, Inter-Services Intelligence (ISI), has been accused of arming, training, and... [to full text]