Search results for "PUMP"
showing 10 items of 471 documents
Modelling of Laser Operation in RPE Nd3+:LiNbO3 Channel Waveguides
2006
In this work, laser action in RPE Nd3+:LiNbO3 is modelled by using the overlapping integrals method. Different pumping schemes, TE or TM, have been considered in order to reproduce the experimental measurements. Calculated results indicate that the slope efficiency remains basically independent on the pumping scheme while the threshold pump power increases for TE pumping.
Physicochemical characteristics and phenotypic diversity of sicilian winter pumpkin (Cucurbita maxima) populations
2017
Six pumpkin genotypes (G1, G2, G3, G4, G5 and G6) were evaluated for their morphological, agronomical and physico-chemical properties under ecological conditions of Sicily (Italy). Considering the agronomical, morphological and physicochemical data including fiber, humidity, pH, total acidity, soluble solids, carotenoids, phenolic and ascorbic acid content, it was possible to differentiate among genotypes. The morphological analysis showed that the pumpkin genotypes did not have a homogenous morphology and present a large physico-chemical characteristic variability. Furthermore, high contents of carotenoids and dietary fiber, soluble solids, phenolic and ascorbic acid were observed with the…
Near-IR-to-visible emission in ytterbium-doped silica fiber at in-core 488-nm pumping
2008
We report near-IR-to-visible broadband emission in Ytterbium-doped silicate fiber (YF) at 488-nm in-core excitation. This emission is revealed to originate from Yb3+-Yb3+ pair clusters (900 – 1200-nm band), whose presence is proved by a separate study of cooperative processes in the fiber, and Yb2+ phototropic centers (600 – 900-nm band) provisionally accepted to be present in the YF.
Mode-locked Yb-doped all-fiber laser based on in-fiber acoustooptic modulation
2011
We show what we believe is the first demonstration of an ytterbium-doped strictly all-fiber active mode-locking laser. The active control of the laser is based on in-fiber amplitude modulation at 11 MHz, which is achieved by using an all-fiber acoustooptic superlattice modulator driven by standing acoustic waves. In our experiments, the laser was operated at 1091.3 nm and had two stable regimes producing either a train of mode-locked single pulses or a train of pulse pairs. Best results for the mode-locked train of single pulses were 740 ps of time width and 26 mW of average power, at a pump power of 480 mW.
SELECTIVE AMPLIFICATION OF NARROW RESONANCE FORMED IN TRANSMISSION SPECTRUM OF Rb NANO-CELL IN MAGNETIC FIELD
2012
Recently it was shown that "λ-Zeeman Technique" (λ-ZT) is a convenient tool to study individual transitions between the Zeeman sublevels of hyperfine levels in an external magnetic field. λ-ZT is based on resonant transmission spectrum of nanometric thin cell (NTC) of thickness L = λ, where λ is the resonant wavelength 794 nm for Rb D1 line. Narrow velocity selective optical pumping (VSOP) resonances in the transmission spectrum of the NTC are split into several components in a magnetic field. Examination of VSOP resonances allows one to identify and investigate an atomic transition in the range of magnetic fields 10 - 5000 G. Here we present a new method for selective addressing of VSOP r…
Lāčplēša tēma latviešu apziņā, literatūrā, mākslā un LU mācībspēku pētījumos
2022
Atzīmējot Andreja Pumpura eposa “Lāčplēsis” 135. gadadienu, kas aprit 2023. gada jūnijā, Humanitāro zinātņu bibliotēkā tika izveidota izstāde "Lāčplēša tēma latviešu apziņā, literatūrā, mākslā un LU mācībspēku pētījumos". Eposs tika publicēts 1888. gada jūnijā saistībā ar Trešo Vispārējo latviešu dziesmu svētku norisēm. Darbs tapis, sintezējot teikas, pasakas un laikabiedru priekšstatus par senatni, saskaņā ar 19. gs. nacionālā romantisma idejām Eiropā laikā, kad eposa esamība tika uztverta kā nācijas eksistences apliecinājums. Izstāde izkārtota 4 plauktos. Pirmajā plauktā izstādīts eposa 1888.gada izdevums. Otrajā plauktā redzami Latvijas Universitātes mācībspēku pētījumi, skatot Lāčplēsi …
Transient collisionally excited X-ray laser in nickel-like zirconium pumped with the PHELIX laser facility
2004
A transient collisionally excited X-ray laser has been put into operation using the front end of the PHELIX laser system as a pump laser. Strong lasing at 22 nm has been observed in nickel-like zirconium.
Passively mode-locked laser based on an ultra-large dispersion Yb-doped fiber
2013
Summary form only given. We report on the first realization of a passively mode-locked oscillator featuring an ultra-large dispersion Yb-doped Bragg fiber. The gain medium is a double-clad Bragg fiber featuring a 20 μm Yb-doped core surrounded by a 120 μm inner cladding [1]. The 2 m long gain fiber is cladding-pumped with a fiber-coupled laser diode emitting at 976 nm. Passive mode locking is achieved by the combined actions of nonlinear polarization evolution and a SESAM. Mode-locking is initiated by optimizing the saturation criteria on the saturable absorber mirror using an adequate focusing lens. The emission wavelength of the oscillator is controlled using a passive spectral filter int…
Nanobox array for silicon-on-insulator luminescence enhancement at room temperature
2006
We report the light extraction enhancement obtained at room temperature from a square lattice of crystalline silicon nanoboxes etched in a silicon-on-insulator substrate. Luminescence spectra recorded under optical pumping show a 125 times emission enhancement as compared with the reference unpatterned silicon-on-insulator emission. In light of band diagram calculations, it is demonstrated that the emission enhancement partially results from the coupling between electron-hole recombination inside the silicon boxes and low group velocity optical modes of the array. Moreover, it is observed that these modes present different decoupling lengths and that a complete extraction of luminescence ca…
Si and Si-rich silicon-nitride waveguides for optical transmissions and nonlinear applications around 2 µm
2019
We show that cm-long silicon and silicon-rich silicon nitride waveguides with subwavelength transverse dimensions can efficiently sustain high-speed transmissions at 2 μm. We report the transmission of a 10 Gbit/s signal with negligible power penalty. Parametric conversion in both continuous and pulsed pump regimes is also demonstrated, as well as the spectral broadening of picosecond pulses.