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Schneider W.,Ludwig Maximilians University of Munich | Schneider W.,Max Planck Institute of Quantum Optics | Ryabov A.,Ludwig Maximilians University of Munich | Ryabov A.,Max Planck Institute of Quantum Optics | And 7 more authors.
Optics Letters | Year: 2014

Yb:YAG thin-disk lasers offer extraordinary output power, but systems delivering femtosecond pulses at a repetition rate of hundreds of kilohertz are scarce, even though this regime is ideal for ultrafast electron diffraction, coincidence imaging, attosecond science, and terahertz (THz) spectroscopy. Here we describe a regenerative Yb:YAG amplifier based on thin-disk technology, producing 800-fs pulses at a repetition rate adjustable between 50 and 400 kHz. The key design elements are a short regenerative cavity and fast-switching Pockels cell. The average output power is 130 Wbefore the compressor and 100 W after compression, which at 300 kHz corresponds to pulse energies of 430 and 330 μJ, respectively. This is sufficient for a wide range of nonlinear conversions and broadening/compression schemes. As a first application, we use optical rectification in LiNbO3 to produce 30-nJ single-cycle THz pulses with 6W pump power. The electric field exceeds 10 kV/cm at acentral frequency of 0.3 THz, suitable for driving structural dynamics or controlling electron beams. © 2014 Optical Society of America.

Adam P.,Hungarian Academy of Sciences | Adam P.,University of Pecs | Mechler M.,MTA PTE High Field Terahertz Research Group | Santa I.,University of Pecs | Koniorczyk M.,University of Pecs
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014

We introduce a theoretical framework which is suitable for the description of all spatial and time-multiplexed periodic single-photon sources realized or proposed thus far. Our model takes into account all possibly relevant loss mechanisms. This statistical analysis of the known schemes shows that multiplexing systems can be optimized in order to produce maximal single-photon probability for various sets of loss parameters by the appropriate choice of the number of multiplexed units of spatial multiplexers or multiplexed time intervals and the input mean photon pair number and reveals the physical reasons of the existence of the optimum. We propose a time-multiplexed scheme to be realized in bulk optics, which, according to the present analysis, would have promising performance when experimentally realized. It could provide a single-photon probability of 85% with a choice of experimental parameters which are feasible according to the experiments known from the literature. © 2014 American Physical Society.

Adam P.,Hungarian Academy of Sciences | Adam P.,University of Pecs | Mechler M.,MTA PTE High Field Terahertz Research Group | Szalay V.,Hungarian Academy of Sciences | Koniorczyk M.,University of Pecs
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014

Recently a new uncertainty relation was found as an alternative to a number-phase uncertainty relation for a harmonic oscillator. In this paper we determine numerically, via the discrete-variable-representation method known from quantum chemistry, the exact states that saturate this new uncertainty relation. We analyze the physical properties of the states and compare them to the intelligent states of the Pegg-Barnett uncertainty relation. We find that for a given set of expectation values of the physical parameters, which are the particle number and the two quadratures, the two kinds of intelligent states are equivalent. The intelligent states are the eigenstates corresponding to the lowest eigenvalue of a Hermitian operator, which, when interpreted as a Hamiltonian of a physical sytem, describes a nonlinear driven harmonic oscillator, for example, a Duffing oscillator for a certain parameter range. Hence, our results can be interpreted as the determination of the ground state of such physical systems in an explicit analytic form as well. As the Pegg-Barnett intelligent states we use are expressed in terms of a coherent-state superposition facilitating experimental synthesis, we relate the states determined here to experimentally feasible ones. © 2014 American Physical Society.

Kovacs L.,Hungarian Academy of Sciences | Szaller Z.,Hungarian Academy of Sciences | Lengyel K.,Hungarian Academy of Sciences | Peter A.,Hungarian Academy of Sciences | And 5 more authors.
Optics Letters | Year: 2013

Several optical methods including ultraviolet absorption, infrared absorption of the hydroxyl ions, Raman spectroscopy, and the Z-scan method have been used to determine the damage resistance threshold in 0-0.72 mol. % Zr-containing, flux-grown, nearly stoichiometric LiNbO3 single crystals. All spectroscopical methods used indicate that samples containing at least ̃0.085 mol: % Zr in the crystal are above the threshold while Z-scan data locate the photorefractive damage threshold between 0.085 and 0.314 mol. % Zr. © 2013 Optical Society of America.

Vicario C.,Paul Scherrer Institute | Monoszlai B.,Paul Scherrer Institute | Monoszlai B.,University of Pecs | Lombosi C.,University of Pecs | And 5 more authors.
Optics Letters | Year: 2013

We present a study on THz generation in lithium niobate pumped by a powerful and versatile Yb:CaF2 laser. The unique laser system delivers transform-limited pulses of variable duration (0.38-0.65 ps) with pulse energies up to 15 mJ and center wavelength of 1030 nm. From previous theoretical investigations, it is expected that such laser parameters are ideally suited for efficient THz generation. Here, we present experimental results on both the conversion efficiency and the THz spectral shape for variable pump pulse durations and for different crystal temperatures, down to 25 K. We experimentally verify the optimum pump parameters for the most efficient and broadband THz generation. © 2013 Optical Society of America.

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