Dacheng Zhou

Effect of photonic bandgap on upconversion emission in YbPO 4 :Er inverse opal photonic crystals

We obtained upconversion (UC) light-emitting photonic materials (YbPO(4):Er) with an inverse opal structure by the self-assembly technique in combination with a solgel method. The effect of the photonic stopband on the UC luminescence of the (2)H(11/2), (4)S(3/2)→(4)I(15/2), and (4)F(9/2)→(4)I(15/2) transitions of Er(3+) has been observed in the inverse opals of the Er(3+)-doped YbPO(4). Significant suppression of the UC emission was detected if the photonic bandgap overlapped with the Er(3+) ions emission band, while enhancement of the UC emission occurs if the emission band appears at the edge of the bandgap.

Optical properties of Ce3+–Nd3+ co-doped YAG nanoparticles for visual and near-infrared biological imaging

Ce(3+)-Nd(3+) co-doped Y3Al5O12 (YAG) nanoparticles, an average size of 20-30 nm clusters aggregated by 8-10 nm YAG nanoparticles, were synthesized by a solvothermal method. When excited by blue irradiation source, strong and broad yellow luminescence (centered at 526 nm) from Ce(3+) as well as near-infrared (NIR) luminescence (890, 1066 and 1335 nm) of Nd(3+) was observed simultaneously. It occurred by the effective dipole-dipole energy transfer from Ce(3+) to Nd(3+). Energy transfer efficiency from Ce(3+) to Nd(3+) was also calculated to be 50%. The optical property suggests that Ce(3+)-Nd(3+) co-doped YAG nanoparticles can be used as an efficient fluorescence imaging agent for not only visual but also near-infrared imaging.

Synthesis and upconversion emission properties of Pb0·9La0·1TiO3:Yb, Tb inverse opals by sol–gel technique

Abstract Inverse opal photonic crystals of Yb3+, Tb3+ codoped Pb0·9La0·1TiO3 were synthesised by a sol–gel technique in combination with a self-assembly method. Opal template was self-assembled from suspensions of monodisperse polystyrene microspheres with a mean diameter of 400 nm via a vertical deposition process. After infiltrating the Yb3+, Tb3+ codoped Pb0·9La0·1TiO3 sol into the opal template, the polystyrene microspheres were removed by calcination at 670°C, and Yb3+, Tb3+ codoped Pb0·9La0·1TiO3 inverse opal photonic crystals were formed. The effect of photonic band gap on upconversion emissions was investigated in the Yb3+, Tb3+ codoped Pb0·9La0·1TiO3 inverse opals. Significant suppression of the upconversion emission was detected if the photonic band gap overlapped with the Tb3+ ions emission band, leading to colour tuneable upconversion photonic crystals with applications in solid state colour displays.

Influence of B2O3 on broad infrared emissions from aluminosilicophosphate glass

Abstract Abstract Influence of B2O3 on broadband near infrared luminescence properties from Bi doped aluminosilicophosphate glass was investigated. It is interesting that the near infrared luminescence showed different behaviour under different pumping sources. In the case of 808 nm excitation, the infrared emission located at 1290 nm was observed, whose intensity increased with increasing B2O3 concentration. However, under a 690 nm excitation, the luminescence at 1110 nm decreased with increasing B2O3 concentration. We ascribed the infrared emissions at 1290 nm to X2(3/2)→X1(1/2) transition of Bi+ and the infrared emissions at 1110 nm to X3A→X1A transition of Bi2+ based on the energy matching conditions. The broadband infrared luminescent characteristics of the glasses indicate that they are promising for broadband optical fibre amplifiers and tunable lasers.