Guangyong Zhou

Growth and properties of (Cr3+, Nd3+) doped GdCa4O(BO3)3 crystals

Abstract Optical quality Nd:GdCa 4 O(BO 3 ) 3 (Nd:GdCOB) crystal and chromium sensitized crystal of Cr:Nd:GdCa 4 O(BO 3 ) 3 (Cr:Nd:GdCOB) were grown by the Czochralski (CZ) method. The transmittance spectra was measured at room temperature on 7at%Nd:GdCOB and lat%Cr:7at%Nd:GdCOB samples. The absorption in the blue-UV region of Cr:Nd:GdCOB was larger than that of Nd:GdCOB, which matched the xenon flash lamp very well. A 3×3×10mm 3 Nd:GdCOB sample without any antireflective coating was sidepumped using a pulsed dye-laser tuned to 595.4nm. The green-light output energy was 1.35mJ at a pump energy of 17.5mJ. The conversion efficiency was 7.7%, and the threshold energy was less than 1.2mJ which are the best results up to now to our knowledge. 3×3×7mm 3 Nd:GdCOB and Cr:Nd:GdCOB samples without antireflective coatings were pumped using a flash pump source. The threshold for Cr:Nd:GdCOB was 0.9J while for Nd:GdCOB it was I.O.J. The output green light energy was 2.46mJ for Cr:Nd:GdCOB at a 10J flash pump energy and was 1.96mJ for Nd:GdCOB at the same pump energy, which clearly shows that Cr 3+ ions have the sensitizing effect on the Nd 3+ ions in Nd:GdCOB crystal.

Two-photon-absorption and upconverted superradiance properties of organic dye HEASPS-doped linear homogeneous polymer at several wavelengths

The spectral and temporal properties of single- and two-photon fluorescence of a dye-doped linear homogeneous polymer are reported. The dopant is a new organic dye, trans-4-[p-(N-hydroxyethyl-N-ethylamino)styryl]-N-methylpyridinium p-toluene sulfonate (HEASPS), synthesized by researchers at the State Key Laboratory, Jinan China. When the dye is excited by near-infrared laser radiation, strong upcoverted fluorescence and superradiance can be observed. The difference in the blueshift of two-photon superradiance compared with that of two-photon fluorescence is explained by the use of different reabsorption coefficients under different conditions. The lifetime of two-photon fluorescence in a solid was measured to be 4.14 ns, which was much longer than that in solution. Two-photon transmittance and upconversion efficiencies at different wavelengths were measured with an optical parameter amplifier as the pump source. The strongest two-photon absorption occurred at 930 nm. The highest upconversion efficiency was 4.05% at 1030 nm. A possible mechanism is discussed.

Two-photon pumped frequency up-converted lasing properties of a new material DEASMPI

A new dye Trans-4-[p-(N,N-diethylamino) styryl]-N- methylpyridinium iodide (abbreviated as DEASMPI) has been synthesized. The two-photon absorption (TPA), TPA-induced frequency up- conversion emission, and two-photon pumped (TPP) frequency up- converted lasing properties of this new dye have also been experimentally studied. This new dye has a moderate TPA cross section of ?2 = 6.9x 10-48 cm4.s/photon at 1064-nm, but exhibits a high lasing efficiency. The net conversion efficiency from the absorbed 1064-nm pump pulse energy to the 628-nm up-converted lasing energy is 3.2% at the pump energy level of 3 mJ.

Properties of picosecond two-photon-absorption induced amplified spontaneous emission and cavity lasing of a new organic dye PSPS

Abstract The properties of picosecond two-photon-absorption induced amplified spontaneous emission (ASE) and cavity lasing of a newly synthesized organic dye, trans-4-(4′-pyrrolidinyl styryl)- N -methyl pyridinium methyl sulfate (abbreviated as PSPS), has been reported in this letter. There is 5 nm red-shift for the central wavelength of two-photon-absorption (TPA) induced lasing compared to that of ASE. The temporal behavior of TPA induced fluorescence, ASE and lasing has been studied. An obvious oscillation can be obtained due to the feedback of the external surface of the cuvette. The oscillation time is more than 200 ps, which is much longer that the pump laser duration (50 ps). The reason why the oscillation time is longer that the pump laser duration has also been given.

Studies on the two-photon pumped upconverted fluorescence and superradiance of a new organic dye material in solutions

The linear and nonlinear optical properties of a new organic dye, trans-4-[p-(N-ethyl-N-ethylamino)-styryl]-N-methyl-pyridinium tris(thiocyanato) cadmates (II), are reported in this paper. When pumped with a picosecond laser at the wavelength range of 850-1200 nm, intense upconversion fluorescence can be obtained. The upconversion efficiencies at different pump energies were measured when pumped with a 1064-nm laser beam from a mode-locked Nd:YAG laser. The highest upconversion efficiencies were measured to be 5.8% and 7.6% in dimethyl formamide (DMF) and methanol. The lifetime of the dye in DMF was measured to be 75 ps. The strongest nonlinear absorption was at the wavelength of 940 nm, and the highest upconversion efficiency was at the wavelength of 1030 nm. The difference of the two wavelengths was caused by excited state absorption in the dye at wavelengths shorter than 1000 nm. The dye solution in DMF and methanol show a clear optical power limiting effect.

Temporal and spectral properties of two-photon pumped upconverted fluorescence and cavity lasing of an organic dye PSPI

Two-photon pumped cavity lasing is firstly operated based on an organic dye, trans-4-[p-(pyrrolidinyl)styryl]-N-methylpyridium iodide, using mode-locked picosecond laser beam at 1064 nm as pump source. There is an obvious blue shift for the central wavelength of cavity lasing compared with that of the two-photon absorption (TPA) induced fluorescence. This phenomenon is explained by using the difference of the re-absorption coefficient at different condition. The lifetime of the fluorescence is measured to be 89 ps. The temporal properties of TPA induced cavity lasing are measured and obvious oscillations can be obtained.

Two-photon pumped upconversion and nonlinear optical properties of a new lasing dye: HMASPS

Abstract Two-photon pumped frequency upconversion optical properties and two-photon absorption (TPA) induced nonlinear absorption of a new dye, trans-4-[p-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium ptoluene sulfonate (abbreviated to HMASPS) have been experimentally investigated. This new dye exhibits strong superradiation properties when the pumping power is above its threshold. The superradiation upconversion efficiency from 900 to 1150 nm and the nonlinear absorption from 720 to 1100 nm have been measured. The largest effective molecular TPA cross-section was measured to be 44.3 × 10−48 cm4·s·photon−1at 920 nm. At 1064 nm, it was 2.77 × 10−48 cm4·s·photon−1, much smaller than that at 920 nm. The highest conversion efficiency is 7% at 990 nm, whereas 4.2% at 1064 nm.

Two-photon absorption and frequency-upconversion properties of a new organic dye HMASPS

Two-photon absorption (TPA) and frequencyupconversion properties of a new upconversion laser dyetrans-4-[p-(N-hydroxyethyl-N-methyl-amino)styryl]-N-methylpyridinium toluene-p-sulfonate (abbreviated to HMASPS) were reported in this note. The linear absorption, TPA, single-photon induced fluorescence, TPA induced fluorescence and TPA induced upconverted lasing spectra of HMASPS solution in dimethyl formamide (abbreviated to DMF) were measured at room temperature. The red shift for the central wavelength of TPA induced fluorescence peak, which was compared with that of the single-photon induced fluorescence peak, and the blue shift for that of TPA induced upconverted lasing compared with that of TPA induced fluorescence, were explained by using re-absorption effect. TPA peak was at 930 nm. There is an 11 nm blue shift for two-photon energy of TPA peak compared with the linear absorption peak. The molecular TPA cross-section σ29′ at 1064 nm was measured to be 6.0×10−48 cm4 · s/photon by using the open aperture Z-scanning system. The highest upconversion efficiency was measured to be 8.4% at 1064 nm.

Optical properties of a new two-photon absorbing chromophore

A new dye, trans-4-[p-(pyrrolidinyl)styryl]-N-methylpyridinium iodide, has been synthesized, and the two-photon-absorption (TPA), TPA-induced frequency upconversion emission, and two-photon-pumped (TPP) frequency upconverted lasing properties of this new dye were experimentally studied. This new dye has a moderate TPA cross section of varsigma(2) = 5.7 x 10(-48) (cm(4) s(-1))/photon at 1064 nm but exhibits high lasing efficiency. The slope efficiency of the TPP cavity laser with this new dye as the laser medium is 1.6%.

Synthesis, growth and doped properties of PbWO4 crystals

Abstract High purity polycrystalline PbWO4 (PWO) has been synthesized by a chemical method. Pure and doped PWO crystals were grown by using a Czochralski technique. Transmittance spectra, light yield and decay constants of the crystal were measured. The effect of PWO crystal quality and doped ions on its scintillating properties is discussed in this paper.