N-methylpyridinium P-toluene Sulfonate Research Articles

Influence of Salt on the Self-Organization in Solutions of Star-Shaped Poly-2-alkyl-2-oxazoline and Poly-2-alkyl-2-oxazine on Heating.

The water–salt solutions of star-shaped six-arm poly-2-alkyl-2-oxazines and poly-2-alkyl-2-oxazolines were studied by light scattering and turbidimetry. The core was hexaaza[26]orthoparacyclophane and the arms were poly-2-ethyl-2-oxazine, poly-2-isopropyl-2-oxazine, poly-2-ethyl-2-oxazoline, and poly-2-isopropyl-2-oxazoline. NaCl and N-methylpyridinium p-toluenesulfonate were used as salts. Their concentration varied from 0–0.154 M. On heating, a phase transition was observed in all studied solutions. It was found that the effect of salt on the thermosensitivity of the investigated stars depends on the structure of the salt and polymer and on the salt content in the solution. The phase separation temperature decreased with an increase in the hydrophobicity of the polymers, which is caused by both a growth of the side radical size and an elongation of the monomer unit. For NaCl solutions, the phase separation temperature monotonically decreased with growth of salt concentration. In solutions with methylpyridinium p-toluenesulfonate, the dependence of the phase separation temperature on the salt concentration was non-monotonic with minimum at salt concentration corresponding to one salt molecule per one arm of a polymer star. Poly-2-alkyl-2-oxazine and poly-2-alkyl-2-oxazoline stars with a hexaaza[26]orthoparacyclophane core are more sensitive to the presence of salt in solution than the similar stars with a calix[n]arene branching center.

Wavelength tunable two-photon-pumped distributed feedback zirconia waveguide lasers

Two-photon-pumped distributed feedback laser action of narrow linewidth output was demonstrated in zirconia waveguides doped with trans-4-[p-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium p-toluene sulfonate, a compound showing strong two-photon upconverted emission around 620 nm. Transient gratings were generated in the waveguides by crossing two nanosecond 1.06 µm beams. Operated at the third-order Bragg resonance condition, tunable narrow linewidth laser emission was observed from 618 to 640 nm by varying the intersection angle of the crossing beams around 61°. Tunable lasing at the second-order Bragg condition was also obtained when the zirconia waveguides were pumped at 532 nm.

Two-photon-pumped amplified spontaneous emission and cavity lasing of an organic dye HEASPS in PHEMA polymer

Two-photon-absorption (TPA)-induced upconverted amplified spontaneous emission (ASE) and cavity lasing of a styrylpyridinium dye: trans-4-[p-(N-hydroxyethyl-N-ethylamino)styryl]-N-methylpyridinium p-toluene sulfonate (abbreviated as HEASPS) in poly(2-hydroxyethyl methacrylate) (abbreviated as PHEMA) polymer were observed under a picosecond pump condition. The spectral and temporal behaviors of TPA-induced fluorescence, ASE and cavity lasing were studied. The cavity lasing with a total oscillation time of more than 200 ps was achieved when pumped with 1064-nm, 50-ps laser irradiation. The population inversion could persist for three times longer than the duration of the pump pulse. The gain coefficients of the dye-doped polymer at various wavelengths were calculated based on cavity lasing spectra and one-photon fluorescence spectra.

Two-photon-pumped distributed feedback zirconia waveguide lasers

Distributed feedback laser action of narrow line-width output was demonstrated in zirconia waveguides doped with trans-4-[p-(N-hydroxyethyl-N-methylamino) styryl]-N-methylpyridinium p-toluene sulfonate, a compound of strong two-photon up-converted emission near 620 nm. Single-beam pumping at 1.06 μm led to intense up-converted amplified spontaneous emission at 620 nm. Transient gratings for coherent scattering were generated in the waveguides by crossing two 1.06-μm beams. Narrow line-width distributed feedback laser emission was observed at 627 nm.

Two-photon-pumped short-cavity lasing properties of the dye <bold>trans</bold>-4-[<bold>p</bold>-(<bold>N</bold>-hydroxyethyl-<bold>N</bold>-methylamino)styryl]-<bold>N</bold>-methylpyridinium <bold>p</bold>-toluene sulfonate

Upconverted lasing pulses could be achieved when 0.01-mol/l trans-4-[p-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium p-toluene sulfonate (HMASPS) solution in dimethyl formamide was pumped in a 5-mm-path glass cell by picosecond lasing pulses from a mode-locked Nd:YAG laser. The upconverted fluorescent time of the solution was measured to be 108 ps. Because of the reflections at the surfaces of the cell, pulse oscillation can be observed in the output lasing pulses. Both the spectral and the temporal behavior of the lasing pulse have been analyzed. As a comparison, the superradiance and lasing from the 5-mm uncoated glass cell are also given.

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.

One- and two-photon absorption induced emission in HMASPS doped polymer

The new laser dye trans-4-[ p-( N-hydroxyethyl- N-methylamino)styryl]- N-methylpyridinium p-toluene sulfonate (abbreviated as HMASPS) doped in a linear homogenous polymer has been studied by the picosecond pulses from mode-locked Nd:YAG laser. The emission wavelengths of the dye in the polymer are all blue-shifted relative to those in the solution. The fluorescence lifetime of the dye in the polymer after the two-photon excitation is 4.4 ns, which is about 60 times longer than that in solution. Several lasing pulses can be burst from the polymer after one pump pulse, in contrast to the amplified spontaneous emission, where only single pulses are observed.

Temporal and spectral properties of picosecond two-photon pumped cavity lasing of an organic dye HEASPS

The operation of cavity lasing of a two-photon absorption (TPA) organic dye, trans-4-[p-(N-hydroxyethyl-N-ethylamino)styryl]-N-methylpyridinium p-toluene sulfonate (abbreviated as HEASPS), by using a picosecond infrared laser as the pump source, is reported. The lifetimes of TPA fluorescence of this dye in different solvents were measured. Temporal profiles of cavity lasing show obvious oscillations and magnification of the feedback light. By using the difference of re-absorption coefficients at different conditions, we explained the blue shift for cavity lasing and superradiance compared with TPA-induced fluorescence. The long lifetime of fluorescence is helpful to the generation of cavity lasing.

Linear and nonlinear optical properties of two-photon absorption dye doped linear copolymer

2-hydroxyethyl methacrylate (abbreviated as HEMA) and acrylonitrile have been used as the monomers to form a trans-4-[p-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium p-toluene sulfonate (abbreviated as HMASPS) doped linear copolymer. The spectra of one and two-photon excited fluorescence and two-photon pumped superradiance and two-photon pumped lasing of the polymer all shifted to short wavelengths compared with the solution sample of the dye. The copolymer shows much longer one- and two-photon excited fluorescence lifetimes of nanoseconds. When pumped by the picosecond Nd:YAG laser, the superradiance and lasing can be simultaneously obtained. The maximum two-photon pumped lasing conversion efficiency is 3.3%. The place of the maximum upconversion efficiency of the copolymer does not coincide with that of the maximum nonlinear absorption.

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

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.

LASING PROPERTIES OF A NEW TWO-PHOTON-ABSORBING MATERIAL TRANS-4-[p- (N-HYDROXYETHYL-N-ETHYLAMINO)STYRYL]- N-METHYLPYRIDINIUM p-TOLUENE SULFONATE

A new dye trans-4-[p-(N-hydroxyethyl-N-ethylamino)styryl]-N-methylpyridinium p-toluene sulfonate (HEASPS) 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 were experimentally studied. This new dye has a TPA cross-section of σ2 = 4.7 × 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 625 nm up-converted lasing energy is 3.6% at the pump energy level of 4 mJ.

Synthesis and Properties of a New Two-photon-absorbed Material Heasps

A new dye Trans-4-[p-(N-hydroxyethyl-N-ethyiamino)styryl]-N-methylpyridinium p-toluene sulfonate (HEASPS) was synthesized, and 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 were experimentally studied. This new dye has a moderate TPA cross-section of\\sigma2 = 4.7 × 10−48 cm4 .s/photon at 1064nm, but exhibits a high lasing efficiency. The net conversion efficiency from the absorbed 1064 nm pump pulse energy to the 626 nm up-converted lasing energy is 18.2% at the pump energy level of 1.9 mJ.

Nonlinear optical properties of a new two-photon-absorption organic dye: HEASPS

Trans-4-[p-(N-hydroxyethyl-N-ethylamino)styryl]-N-methylpyridinium p-toluene sulfonate (abbreviated as HEASPS) is a two-photon-absorption (TPA) dye newly synthesized by our research group. It possesses a much larger TPA cross-section and much stronger upconversion fluorescence emission than those of common organic dyes (such as rhodamine) when excited with near-infrared (IR) radiation. TPA spectrum and upconversion efficiency spectrum of HEASPS solution at different wavelengths have been measured. The largest molecular TPA cross-section σ2 ′ is measured to be 2.06×10-47 cm4 s/photon at 930 nm. At 1064 nm, σ2 ′ is 2.71×10-48 cm4 s/photon, which is only one-ninth of that at 930 nm. The upconverted lasing efficiency spectrum has been measured at different wavelengths. The highest efficiency is 5.1% at 1020 nm, whereas it is 3.5% at 1064 nm. Its optical-power-limiting properties at 930 nm have also been illustrated.

Two-photon Absorption and Nonlinear Optical Properties of a New Organic Dye Trans-4-[p-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium p-toluene Sulfonate

Trans-4-[p-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium p-toluene sulfonate (abbreviated as HMASPS) is a newly synthesized dye that possesses a much greater two-photon-absorption (TPA) cross-section and much stronger upconversion fluorescence emission than common dyes (such as rhodamine) when excited with near infrared laser radiation. TPA induced upconverted lasing has been obtained in HMASPS solution in dim eth ylformamide (abbreviated as DMF) pumped by near infrared laser beam from 900 to 1150 nm. The central wavelength and bandwidth of the lasing are 626 nm and 26 nm. The upconversion efficiencies of 1cm-path HMASPS solution in DMF at 0.05 mol/l concentration at different wavelengths from 900 to 1150 nm were measured. The net upconversion efficiency from the absorbed pump energy to the upconverted lasing output was 14% at the pump energy level of 2.04 mJ when the pump laser beam was provided by Nd:YAG laser. The molecular TPA cross-section at 1064 nm was σ2=6.0×10-48 cm4·s/photon measured by using an open aperture Z-scan system. The linear absorption, single-photon induced fluorescence, two-photon induced fluorescence and two-photon induced upconverted lasing properties have also been studied in this paper.