A passively Q-switched Tm,Ho:GdVO4 laser operating at cryogenic temperature with a Cr(2+):ZnS saturable absorber pumped with continuous wave LDs was demonstrated. The performance of the laser was investigated through changing the distance between Cr(2+):ZnS and output coupler. The maximum pulse energy of 70.5 μJ was obtained at 10 W input power. The maximum average output power of PQS laser was up to 3.2 W at the pump power of 22.8 W, corresponding to CW output power of 7.4 W, pulse repetition frequency of 52 kHz, and a pulse width of 389 ns. The M(2) factor measured by the traveling knife-edge method was ~1.1 in x and y directions with near-diffraction limited beam quality.
Durable solar cells with tunable color and diaphaneity are very promising for building integrated photovoltaic applications. In this paper we employ donor−acceptor organic dyes U3, U4, U5, and R6 featured by polycyclic heteroaromatics 6,12 and 9,19 [3,4-d]thiophene (BPT2) to fabricate semitransparent dyesensitized solar cells (DSSCs). The U3-, U4-, U5-, and R6-based cells are goldenrod, crimson, red, and sapphire blue, with power conversion efficiencies of 3.5%, 8.2%, 7.6%, and 10.1% at the AM1.5G conditions, respectively. Density functional theory calculations reveal that lateral π-extension of the polycyclic heteroaromatic brings forth a downward displacement of lowest unoccupied molecular orbital, affording a highmolar-extinction-coefficient, low-energy-gap blue dye. Femtosecond fluorescence decay measurements of dyed titania and alumina films unravel the electron injection yields of photoexcited dye molecules, which are well correlated with the maximal values of external quantum efficiencies of DSSCs. After 1000 h full sunlight soaking at 60 °C, the red and blue DSSCs exhibit stable photocurrents, owing to the strong bonding and photochemical stability of dye molecules adsorbed on the surface of titania as well as the retention of close-to-unity electron collection yield.
A stable diode-pumped passively Q-switched Tm,Ho:YVO4 laser with Cr:ZnS saturable absorber is reported. The shortest pulse duration of ∼500 ns with the central wavelength of 2041 nm is obtained at the pump power of 7.4 W, corresponding to the pulse energy of 3.5 𝜇J at repetition rate of 65 kHz.
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