Qiu Jianrong

Broadband infrared luminescence from bismuth-doped GeS2-Ga2S3 chalcogenide glasses

Near-infrared luminescence is observed from bismuth-doped GeS2—Ga2S3 chalcogenide glasses excited by an 808 nm laser diode. The emission peak with a maximum at about 1260 nm is observed in 80GeS2-20Ga2S3:0.5Bi glass and it shifts toward the long wavelength with the addition of Bi gradually. The full width of half maximum (FWHM) is about 200 nm. The broadband infrared luminescence of Bi-doped GeS2-Ga2S3 chalcogenide glasses may be predominantly originated from the low valence state of Bi, such as Bi+. Raman scattering is also conducted to clarify the structure of glasses. These Bi-doped GeS2-Ga2S3 chalcogenide glasses can be applied potentially in novel broadband optical fibre amplifiers and broadly tunable laser in optical communication system.

Femtosecond Laser-Written Waveguides in a Bismuth Germanate Single Crystal

We demonstrate the fabrication of symmetric waveguides in a bismuth germanate (BGO) single crystal using a double line approach by an 800 nm femtosecond laser. The optical attenuation of the single mode waveguide is measured to be 4.2 dB/cm at 633 nm. The influence of pulse energy and focal depth on the end facet of the irradiated region is also studied. This technique is promising to fabricate buried BGO waveguide arrays used in positron emission tomography systems.

Cooperative Quantum Cutting of Nano-Crystalline BaF2:Tb3+, Yb3+ in Oxyfluoride Glass Ceramics

We report on cooperative quantum cutting in Tb3+-Yb3+ codoped glass ceramics. Precipitation of BaF2 nano-crystals is confirmed by XRD and HRTEM analysis. Near-infrared emission due to transition of Yb3+ ions under 485 nm excitation indicates cooperative energy transfer from Tb3+ to Yb3+. The quantum efficiency of this process reaches 145%. The realization of quantum cutting in glass ceramics may have promising applications in solar cells.

Transparent Ni2+-Doped MgO-Al2O3-SiO2 Glass Ceramics with Broadband Infrared Luminescence

We report transparent Ni2+-doped ZnO-Al2O3-SiO2 system glass-ceramics with broadband infrared luminescence. After heat-treatment, ZnAl2O4 crystallite was precipitated in the glasses, and its average size increased with increasing heat-treatment temperature. No infrared emission was detected in the as-prepared glass samples, while broadband infrared luminescence centered at 1310 nm with full width at half maximum (FWHM) of about 300 nm was observed from the glass-ceramics. The peak position of the infrared luminescence showed a blue-shift with increasing heat-treatment temperature, but a red-shift with an increase in NiO concentration. The mechanisms of the observed phenomena were discussed. These glass-ceramics are promising as materials for super broadband optical amplifier and tunable laser. (c) 2006 Elsevier Ltd. All rights reserved.

Tunable Infrared Luminescence and Optical Amplification in PbS Doped Glasses

PbS-doped glasses are prepared. Absorption and luminescence spectra show that both the absorption and infrared emission can be tuned widely by thermal treatment conditions. Optical amplification at 1300nm is observed, and amplified spontaneous emission (ASE) spectrum is also measured to confirm the optical gain from PbS quantum dots.

Self-assembled quasi-periodic voids in glass induced by a tightly focused femtosecond laser

Multiple refocusing of a tightly focused femtosecond laser due to the dynamic transformation between self-focusing and self-defocusing is employed to provide a novel method to produce quasi-periodic voids in glass. It is found that the diameter or the interval of the periodic voids increases with the increasing pulse energy of the laser. The detailed course for producing periodic voids is discussed by analysing the damaged track induced by the tightly focused femtosecond laser pulses. It is suggested that this periodic structure has potential applications in fabrication of three-dimensional optical devices.

Blue-to-Orange Tunable Luminescence from Europium Doped Yttrium–Silicon–Oxide–Nitride Phosphors

Europium-doped yttrium–silicon–oxide–nitride phosphors are synthesized by carbothermal reduction and nitri-dation method. The crystal structure of the phosphors changed gradually from oxide Y2 Si2 O7 to nitride YSi3 N5 state with increasing dosage of Si3N4 and carbon powder. The Y2 Si2 O7: Eu phosphor shows a blue emission at 465nm with 300nm excitation and a characteristic red emission of Eu3+ at 612nm with 230nm excitation. The YSi3 N5: Eu phosphor shows a broad emission band centred at 595nm with some sharp peaks of Eu3+ with 325nm excitation. The absorption of the studied phosphors increases from 450 to 700 nm with an increment in nitrogen content. Blue-to-orange tunable luminescence is observed with 390 nm excitation.

Nd3+ Doped Silicate Glass Photonic Crystal Fiber with Random Hole Distributions

Abstract The fabrication of one kind of large core area Nd 3+ doped silicate glass photonic crystal fiber, and demonstration of the fibers waveguidence properties were reported. This fiber owns a random air hole distribution in the cladding. The measured minimum loss of this kind of fiber is 10 dB· m −1 at 660 nm. These fibers can sustain only a single mode at least over wavelength ranging from 660 nm to 980 nm.

Broadband Near-Infrared Emission from Transparent Ni2+-Doped Sodium Aluminosilicate Glass Ceramics

Broadband near-infrared emission from transparent Ni2+-doped sodium aluminosilicate glass-ceramics is observed. The broad emission is centred at 1290 nm and covers the whole telecommunication wavelength region (1100–1700 nm) with full width at half maximum of about 340 nm. The observed infrared emission could be attributed to the 3T2(F)→3A2(F) transition of octahedral Ni2+ ions that occupy high-field sites in nanocrystals. The product of the lifetime and the stimulated emission cross section is 2.15×10−24 cm2s. It is suggested that Ni2+-doped sodium aluminosilicate glass ceramics have potential applications in tunable broadband light sources and broadband amplifiers.

Structural Change in Au3+-Doped BK7 Glass Irradiated by Femtosecond Laser

We report on structural change in an Au3+-doped BK7 glass irradiated by an infrared femtosecond laser at 800 nm. A grating structure is inscribed in the glass sample. The glass sample is then annealed at various temperatures. Structural change of the grating is observed by an optical microscope. Absorption spectra indicate that colour centres are induced after the laser irradiation, and they decrease with increasing annealing temperature. Au nanoparticles are precipitated at high temperatures (≥600°C). The mechanisms of the phenomena are discussed.