Broadband optical amplification near 1300 nm in bismuth-doped germanate glass

In this paper, we present the broadband optical amplification in bismuth-doped germanate glass, at the second telecommunication window when excited with 808 nm and 980 nm laser diodes, respectively. The amplification range is from 1272 nm to 1348 nm wavelength, which is within the O-band of silica fiber communication. This bismuth-doped glass can be used as ultra broadband amplification material for wavelength-division-multiplexing (WDM) at the second telecommunication window.

Intense infrared luminescence in transparent glass-ceramics containing beta-Ga2O3 : Ni2+ nanocrystals

Transparent glass-ceramics containing beta-Ga2O3:Ni2+ nanocrystals were synthesized and characterized by X-ray diffraction, transmission electron microscopy, and electron energy loss spectroscopy. Intense broad-band luminescence centering at 1200 nm was observed when the sample was excited by a diode laser at 980 nm. The room-temperature fluorescent lifetime was 665 mu s, which is longer than the Ni2+-doped ZnAl2O4 and LiGa5O8 glass-ceramics and is also comparable to the Ni2+-doped LiGa5O8 single crystal. The intense infrared luminescence with long fluorescent lifetime may be ascribed to the high crystal field hold by Ni2+ and the moderate lattice phonon energy of beta-Ga2O3. The excellent optical properties of this novel material indicate that it might be a promising candidate for broad-band amplifiers and room-temperature tunable lasers.

Transparent Ni2+-doped lithium-alumino-silicate glass-ceramics for broadband near-infrared light source

Broadband infrared luminescence centred at around 1300 nm with full-width at half maximum of about 342 nm was observed from transparent Ni2+-doped lithium-alumino-silicate glass-ceramics embedded with beta-eucryptite crystallines. The room temperature fluorescent lifetime was 98 mu s. The transparent glass-ceramics may have potential applications in a widely tunable laser and a super-broadband optical amplifier for optical communications.

Ridge optical waveguide in an Er3+/Yb3+ co-doped phosphate glass produced by He+ ion implantation combined with Ar+ ion beam etching

This paper reports on the fabrication and characterization of a ridge optical waveguide in an Er3+/Yb3+ co-doped phosphate glass. The He+ ion implantation (at energy of 2.8 MeV) is first applied onto the sample to produce a planar waveguide substrate, and then Ar+ ion beam etching (at energy of 500 eV) is carried out to construct rib stripes on the sample surface that has been deposited by a specially designed photoresist mask. According to a reconstructed refractive index profile of the waveguide cross section, the modal distribution of the waveguide is simulated by applying a computer code based on the beam propagation method, which shows reasonable agreement with the experimentally observed waveguide mode by using the end-face coupling method. Simulation of the incident He ions at 2.8 MeV penetrating into the Er3+/Yb3+ co-doped phosphate glass substrate is also performed to provide helpful information on waveguide formation.

Mechanisms of Yb3+ sensitization to Tm3+ for blue upconversion luminescence in fluorophosphate glass

The sensitization mechanisms of Yb3+ to Tm3+ for the blue upconversion luminescence in fluorophosphate glass were studied. Two different mechanisms exist in the sensitization. One is the sequential sensitization that Tm3+ is excited from H-3(6) to (1)G(4) through absorbing three photons transferred from Yb3+ one by one. Another is the cooperative sensitization that two Yb3+ ions form a couple cluster firstly, and then the couple cluster Yb3+ ions transfer their energy to Tm3+ and excite it to (1)G(4). With the increment of the concentration of Yb3+ ions, the sequential sensitization becomes weak and the cooperative sensitization becomes intense, and the transformation trend of sensitization mechanism with the increment of Yb3+ concentration can be clarified by the introduction of Th3+ ions in the glass. (c) 2006 Elsevier B.V. All rights reserved.

Multicolor upconversion of Er3+/Tm3+/Yb3+ doped oxyfluoride glass ceramics

Er3+/Tm3+/Yb3+ tricloped oxyfluoride glass ceramics was synthesized in a general way. Under 980 nm LD pumping, intense red, green and blue upconversion was obtained. And with those primary colors, multicolor luminescence was observed in oxyfluoride glass ceramics with various dopant concentrations. The red and green upconversion is consistent with F-4(9/2) -> I-4(15/2) and H-2(11/2), S-4(3/2) -> I-4(15/2) transition of Er3+ respectively. While the blue upconversion originates from (1)G(4) -> H-3(6) transition of Tm3+. This is similar to that in Er3+/Yb3+ and/or Tm3+/Yb3+ codoped glass ceramics. However the upconversion of Tm3+ is enhanced by the energy transfer between Er3+ and Tm3+. (c) 2006 Published by Elsevier B.V.

Tuning the Eu luminescence in glass materials synthesized in air by adjusting glass compositions

The doped Eu3+ ions can be partly reduced to Eu2+ in a series of MO-B2O3: Eu (M=Ba, Sr, Ca) glasses synthesized in air atmosphere, but not in the 12CaO-7Al(2)O(3): Eu glass. The different redox-behavior of Eu ions in these two glass systems is attributed to the different host optical basicity. It is found that a lower valence state of Eu2+ is more favorable in acidic glasses, which have lower optical basicities. A notion of the critical value of optical basicity is introduced empirically, which can be used as a guide for the selection of glass composition suitable to incorporate Eu2+ for luminescence. (C) 2006 Elsevier B.V. All rights reserved.

New transparent Er3+-doped oxyfluoride tellurite glass ceramic with improved near infrared and up-conversion fluorescence properties

Transparent glass ceramics have been obtained by nucleation and growth of Y2Te6O15 or Er2Te5O13 cubic phase in a new Er3+-doped oxyfluoride tellurite glass. Effect of beat treatment on absorption spectra, luminescence and up-conversion properties in the oxyfluoride tellurite glass has been investigated. With heat treatment the ultraviolet absorption edge red shifted evidently for the oxyfluoride telluride glass. The near infrared emission that corresponds to Er3+:I-4(13/2)-> I-4(15/2) can be significantly enhanced after heat treatment. Under 980 nm LD pumping, red and green up-conversion intensity of Er3+ in the glass ceramic can be observed much stronger than that in the base glass. (C) 2006 Elsevier B.V. All rights reserved.

Broadband optical amplification in silicate glass-ceramic containing beta-Ga2O3 : Ni2+ nanocrystals

We demonstrate broadband optical amplification at 1.3 mu m in silicate glass-ceramics containing beta-Ga2O3:Ni2+ nanocrystals with 980 nm excitation for the first time. The optical gain efficiency is calculated to be about 0.283 cm(-1) when the excitation power is 1.12 W. The optical gain shows similar wavelength dependence to luminescence properties. (C) 2007 Optical Society of America.

Bismuth-doped zinc aluminosilicate glasses and glass-ceramics with ultra-broadband infrared luminescence

Broadband infrared luminescence covering the optical telecommunication wavelength region of 0, E and S bands was observed from bismuth-doped zinc aluminosilicate glasses and glass-ceramics. The spectroscopic properties of the glasses and glass-ceramics depend on the thermal-treatment history. With the appearance of gahnite (ZnAl2O4) crystalline phase, the fluorescent peak moves to longer wavelength, but the fluorescent intensity decreases. The similar to 1300 nm fluorescence with a FWHM larger than 250 nm and a lifetime longer than 600 mu s possesses these optical materials with potential applications in laser devices and broadband amplifiers. The broad infrared luminescence from the bismuth-doped zinc aluminosilicate glasses and glass-ceramics might be from BiO or bismuth clusters rather than from Bi5+ and Bi3+. (c) 2005 Elsevier B.V. All rights reserved.

Blue upconversion Luminescence in Tm3+/Yb3+-Codoped New Oxyfluoride Tellurite Glass

The thermal stability, Raman spectrum and upconversion properties of Tm^(3+)/Yb^(3+) co-doped new oxyfluoride tellurite glass are investigated. The results show that Tm^(3+)/Yb^(3+) co-doped oxyfluoride tellurite glass possesses good thermal stability, lower phonon energy, and intense upconversion blue luminescence. Under 980-nm laser diode (LD) excitation, the intense blue (475 nm) emission and weak red (649 nm) emission corresponding to the 1G4 -> 3H6 and 1G4 -> 3F4 transitions of Tm^(3+) ions respectively, were simultaneously observed at room temperature. The possible upconversion mechanisms are evaluated. The intense blue upconversion luminescence of Tm^(3+)/Yb^(3+) co-doped oxyfluoride tellurite glass can be used as potential host material for the development of blue upconversion optical devices.

Gain characteristics of Er3+-doped phosphate glass fibres

An erbium-doped phosphate glass fibre has been drawn by the rod-in-tube technique in our laboratory. The gain for the Er3+-doped phosphate glass fibre with different pump powers and with different input signal wavelengths is investigated. The 2.2-cm-long fibre, pumped by a single-mode 980-nm fibre-pigtailed laser diode, can provide a net gain per unit length greater than 1.8dB/cm. The pump threshold is about 50 mW at the wavelength of 1534 nm, and below 70 mW at 1550 nm. The gain linewidth of the Er3+-doped phosphate glass fibre is greater than 34 nm and can cover the C band in optical communication networks.

Special effects of YbF3 on the structural changes for fluorophosphate glass

From Raman and IR spectra, obvious differences of the glass structure were observed in non-Yb3+-doped and Yb3+ -doped fluorophosphate glasses. Results showed that Yb3+ ions can induce, in a better glass, polymerization and network uniformity. Compared with the monophosphate-mastered Yb3+-free glass, Yb3+-doped glass has a pyrophosphate environment. The main building blocks in Yb3+ -doped samples are metaphosphate groups, pyrophosphate groups (P-2(O,F)(7),PO3F), Al[F-6]+Al[O,F](6) and F3Al-O-AlF3 while those of the Yb3+ -free glasses are monophosphate groups P(O,F)(4), little pyrophosphate groups, Al[F-4]+Al[F-6]+Al[O,F](4)+Al[O,F](6) and F3Al-O-AlF3. The DSC analysis also showed a slight increase in crystallization stability. (c) 2005 Elsevier B.V. All rights reserved.

Efficient frequency upconversion emission in Er3+-doped novel strontium lead bismuth glass

Er3+ -doped strontium lead bismuth glass for developing upconversion lasers has been fabricated and characterized. The Judd-Ofelt intensity parameters Omega(1) (t = 2,4,6), calculated based on the experimental absorption spectrum and Judd-Ofelt theory, were found to be Omega(2) = 2.95 x 10(-20), Omega(4) = 0-91 X 10(-20), and Omega(6) = 0.36 x 10(-20) cm(2). Under 975 nm excitation, intense green and red emissions centered at 525, 546, and 657 nm, corresponding to the transitions H-2(11/2) --> I-4(15/2), S-4(3/2) I-4(15/2), and F-4(9/2) --> I-4(15/2) respectively were observed. The upconversion mechanisms are discussed based oil the energy matching and quadratic dependence on excitation power, and the dominant mechanisms are excited state absorption and energy transfer upconversion for the green and red emissions. The long-lived I-4(11/2) level is supposed to serve as the intermediate state responsible for the upconversion processes. (C) 2004 Published by Elsevier B.V.