ABSTRACT
We report the first short-pulse amplification results to several hundred millijoule energies in ceramic Yb:LuAG. We have demonstrated ns-pulse output from a diode-pumped Yb:LuAG amplifier at a maximum energy of 580 mJ and a peak optical-to-optical efficiency of 28% at 550 mJ. In cavity dumped operation of a nanosecond oscillator we obtained 1 mJ at up to 100 Hz repetition rate. A gain bandwidth of 5.4 nm was achieved at room temperature by measuring the small-signal single-pass gain. Furthermore, we compared our results with Yb:YAG within the same amplifier system.
Subject(s)
Amplifiers, Electronic , Ceramics/chemistry , Lasers, Solid-State , Energy Transfer , Equipment Design , Equipment Failure AnalysisABSTRACT
We report on spectral combination of four high repetition rate 5 ns pulsed Yb-doped fiber amplifiers at 1 microm wavelength. The output beam is spatially and temporally superposed by use of an all-reflective diffraction grating. 1.1 kW average power and 220 microJ pulse energy were extracted with a combining efficiency of 99%.
ABSTRACT
We report on beam combining of four narrow-linewidth fiber amplifier chains, running at different wavelengths and each delivering 500 W optical output power. The main amplifier stage consists of a large mode area photonic crystal fiber. The four output beams of the amplifier chains are spectrally (incoherent) combined using a polarization-independent dielectric reflective diffraction grating to form an output beam of 2 kW continuous-wave optical power with good beam quality (M(2)x = 2.0, M(2)y = 1.8).
ABSTRACT
This article deals with the physical principles of the Doppler ultrasonography. It also describes the performance specification of present-day ultrasonic devices used in clinical practice to diagnose cerebral vessel disorders. In addition, this article presents typical blood-flow indices for different regions of extra- and intracranial vessels under normal or stenotic conditions.
