Jie Xu

Optical amplification of Eu(DBM)3Phen-doped polymer optical fiber

A preform technique is used to prepare a step-index (SI) polymer optical fiber (POF) doped with Eu(DBM)3Phen. The gain (5.7 dB) at 613 nm of the doped SI POF with Eu3+ content of 4000 in 10(6) wt., 0.4-mm core diameter, and 30-cm fiber length is observed at ambient temperature by end pumping with a YAG at 355 nm. The input signal light is approximately 0.2 W. The results show the possibility of signal gain in a rare-earth-doped POF amplifier and the potential of a polymer doped with rare-earth ions as an active optical device.

Radiative properties of Eu(DBM)3Phen-doped poly(methyl methacrylate)

Eu(DBM) 3 Phen-doped poly(methyl methacrylate) (PMMA) with different doping concentrations was prepared. Judd–Ofelt parameters Ω 2 and Ω 4 and the fluorescence intensity ratio R were computed from the fluorescence emission spectra and were analyzed. The radiative properties, such as transition probabilities, emission cross section (46.47 × 10 −22 cm 2 ), fluorescence branching ratios (90.34%), and radiative lifetime (1.704 ms), reveal that Eu(DBM) 3 Phen-doped PMMA has potential use as a laser material.

Sm(DBM)~3Phen-doped poly(methyl methacrylate) for three-dimensional multilayered optical memory

We report on the formation of submicrometer voids within Sm(DBM)3Phen-doped poly(methyl methacrylate) (PMMA) under multiphoton absorption excited by an infrared laser beam. An ultrashort-pulsed laser beam with a pulse width of 200 fs at a wavelength of 800 nm is focused into doped PMMA. The large changes in refractive index and the fluorescence associated with a void allow conventional optical microscopy and reflection-type confocal microscopy to be used as detection methods. Voids can be arranged in a three-dimensional multilayered structure for high-density optical data storage.

Nano-scale study of microstructure of Eu(DBM) 3 phen-doped poly(methyl methacrylate) by near-field scanning microscopy and optical properties

Eu(DBM) 3 phen-doped poly(methyl methacryate) (PMMA) with different doping concentration were prepared. The highest doping concentration sample (10000 ppm) was examined by near-field scanning optical microscopy (NSOM) with a resolution of 50 nm; and the result showed that there were no aggregates larger than 50 nm in the doped polymer. This result was further confirmed by optical properties of the doping material. Concentration quenching was not detected by metastable-state lifetime measurements, indicating that no aggregates existed. According to the fluorescence spectra analysis, the relative intensity ratio (R) of 5 D 0 → 7 F 2 to 5 D 0 → 7 F 1 transition was not shown to be significantly changed with the increasing of Eu 3+ content. The analysis reflected that the local structure and asymmetry in the vicinity of europium ions were not changed, and that the Eu 3+ ions in PMMA were homogeneously dispersed.

Optical Properties of Polymethyl Methacrylate Doped with Neodymium Chelates

Abstract The luminescence of Nd(DBM)3(H2O)2‐, Nd(DBM)3Phen‐, and Nd(DBM)3(TOPO)2‐doped polymethyl methacrylate (PMMA) was investigated under excitation at 17,100xa0cm−1 (4I9/2→4G7/2). The 4F3/2→4I11/2 transition of the Nd(DBM)3(TPPO)2‐doped PMMA showed the strongest intensity. In order to predict the radiative properties of Nd(DBM)3(TOPO)2‐doped PMMA, its absorption spectrum was measured and Judd‐Ofelt parameters (Ω2,xa0Ω4,xa0Ω6) were calculated. The values of the radiative lifetime and the emission cross‐section of 4F3/2→4I11/2 transition are comparable with those shown by glasses used in solid state laser applications. It can be concluded that Nd(DBM)3(TOPO)2‐doped PMMA is an efficient luminescent material.

Unique Free‐Volume Change During the Phase Separation of Poly(N‐isopropylacrylamide) Aqueous Solution Studied by Positron Annihilation Lifetime Spectroscopy

Abstract The change in free‐volume during phase separation of poly(N‐isopropylacrylamide) (PNIPAM) aqueous solution was studied in situ by positron annihilation lifetime spectroscopy. The average size of a free‐volume nanohole exhibited a co‐nonsolvent change, affirming the trans‐to‐gauche conformational change of PNIPAM chains during phase separation. The results obtained for the ortho‐positron (o‐Ps) intensity accounted for the competitive effects of the variations in composition of the free C˭O group and the free amino group on the o‐Ps formation.