Upconversion of infrared-to-visible light in Pr 3+–Yb 3+ codoped fluoroindate glass (original) (raw)
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Journal of Applied Physics, 2000
Infrared-to-visible upconversion emission enhancement through thermal effects in Yb 3ϩ-sensitized Pr 3ϩ-doped fluoroindate glasses excited at 1.064 m is investigated. A twentyfold increase in the 485 nm blue emission intensity as the sample temperature was varied from 20 to 260°C was observed. The visible upconversion fluorescence enhancement is ascribed to the temperature dependent multiphonon-assisted anti-Stokes excitation of the ytterbium sensitizer and excited-state absorption of the praseodymium acceptor. A model based upon conventional rate equations considering a temperature dependent effective absorption cross section for the 2 F 7/2 → 2 F 5/2 transition of the Yb 3ϩ and 1 G 4 → 3 P 0 excited-state absorption of the Pr 3ϩ , agrees very well with the experimental results.
Journal of Applied Physics, 2000
Infrared-to-visible upconversion emission enhancement through thermal effects in Yb 3ϩ-sensitized Pr 3ϩ-doped fluoroindate glasses excited at 1.064 m is investigated. A twentyfold increase in the 485 nm blue emission intensity as the sample temperature was varied from 20 to 260°C was observed. The visible upconversion fluorescence enhancement is ascribed to the temperature dependent multiphonon-assisted anti-Stokes excitation of the ytterbium sensitizer and excited-state absorption of the praseodymium acceptor. A model based upon conventional rate equations considering a temperature dependent effective absorption cross section for the 2 F 7/2 → 2 F 5/2 transition of the Yb 3ϩ and 1 G 4 → 3 P 0 excited-state absorption of the Pr 3ϩ , agrees very well with the experimental results.
Infrared, blue and ultraviolet upconversion emissions in Yb3+–Tm3+-doped fluoroindate glasses
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 1999
Intense ultraviolet (362.5 nm), blue (479 nm) and IR (800 nm) upconversion emissions were obtained in fluoroindate glasses co-doped with Yb 3 + and Tm 3 + ions pumped at 975 nm. The dependence of these upconversion emissions on excitation intensity has been studied and it is concluded that emissions come from Tm 3 + ions excited by successive energy transfers from Yb 3 + ions. The temporal evolution of the 800 nm upconversion emission obtained under flash excitation at 975 nm cannot be described using the energy migration model. This indicates that at this concentration of Yb 3 + , the rapid migration regime among these ions has not been reached. A model is proposed in order to explain the temporal evolution of this emission, taking into account back-transfer processes from Tm 3 + to Yb 3 + ions.
Visible to infrared energy conversion in Pr 3+–Yb 3+ co-doped fluoroindate glasses
Processes involving visible to infrared energy conversion are presented for Pr 3+ -Yb 3+ co-doped fluoroindate glasses. The emission in the visible and infrared regions, the luminescence decay time of the Pr 3+ : 3 P 0 ? 3 H 4 (482 nm), Pr 3+ : 1 D 2 ? 3 H 6 (800 nm), Yb 3+ : 2 F 5/2 ? 2 F 7/2 (1044 nm) transitions and the photoluminescence excitation spectra were measured in Pr 3+ samples and in Pr 3+ -Yb 3+ samples as a function of the Yb 3+ concentration. In addition, energy transfer efficiencies were estimated from Pr 3+ : 3 P 0 and Pr 3+ : 1 D 2 levels to Yb 3+ : 2 F 7/2 level. Down-Conversion (DC) emission is observed due to a combination of two different processes: 1-a one-step cross relaxation (Pr 3+ : 3 P 0 ? 1 G 4 ; Yb 3+ : 2 F 7/2 ? 2 F 5/2 ) resulting in one photon emitted by Pr 3+ ( 1 G 4 ? 3 H 5 ) and one photon emitted by Yb 3+ ( 2 F 7/2 ? 2 F 5/2 ); 2-a resonant two-step first order energy transfer, where the first part of energy is transferred to Yb 3+ neighbor through cross relaxation (Pr 3+ : 3 P 0 ? 1 G 4 ; Yb 3+ : 2 F 7/2 ? 2 F 5/2 ) followed by a second energy transfer step (Pr 3+ : 1 G 4 ? 3 H 4 ; Yb 3+ : 2 F 7/2 ? 2 F 5/2 ). A third process leading to one IR photon emission to each visible photon absorbed involves cross relaxation energy transfer (Pr
Infrared-to-visible CW frequency upconversion in Er 31 -doped fluoroindate glasses
2000
We report on efficient frequency upconversion in Er 3ϩ -doped fluoroindate glasses. The process is observed under 1.48 m laser diode excitation and results in the generation of strong blue ͑ϳ407 nm͒, green ͑ϳ550 nm͒, and red ͑ϳ670 nm͒ radiation. The main mechanism that allows for upconversion appears to be the energy transfer among Er 3ϩ ions in excited states. The results illustrate the large potential of this new class of glasses for photonic applications.
Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications VII, 2008
There has recently been a great deal of interest in searching for new vitreous materials for application as hosts in infrared-to-visible light upconverters or optical amplifiers based upon rare-earth doped systems. Some of their many applications include: color displays, high density optical recording, biomedical diagnostics, infrared laser viewers and indicators, fiber lasers and amplifiers. Fluorophosphate-based glasses have recently emerged as auspicious candidates for such photonic devices applications. These glasses are advantageous because they present low nonlinear refractive indeces, better mechanical strength, chemical durability, and thermal stability than fluoride-based glasses and are suitable for developing low-loss, high strength, and low-cost optical fibers. It has recently been shown also that the fluorophosphate-based glass is an excellent candidate for high power lasers and broadband amplifiers in the eye-safe region around 1.5 µm for applications in communication, medicine, and meteorology. The present work involves the investigation of optical transitions and upconversion fluorescence spectroscopy of trivalent lanthanide ions Er3+ and Tm3+ codoped with Yb3+ in P2O5-PbO-MgF2 glass, excited with near-infrared diode lasers. The dependence of the upconversion luminescence upon the Yb3+-concentration and diode laser power, and the upconversion excitation mechanisms involved are also investigated. The viability of using these glasses as host for practical applications in optical temperature sensors will also be presented.
Optical amplification by upconversion in Tm–Yb fluoroindate glass
Optical Materials, 2010
Evidence of a positive optical gain at 650 nm is observed in Tm 3+-Yb 3+ codoped fluoroindate glass in an upconversion pump and probe experiment. The 1 G 4 level of the Tm 3+ ions is populated by an upconversion mechanism under excitation of the Yb 3+ ions at 975 nm with high power pulsed laser and give rise to an intense emission from the 1 G 4 to the 3 F 4 levels. The 1 G 4 ? 3 F 4 electronic transition is stimulated with a low signal at 650 nm as a probe. Under this condition, we reach the population inversion necessary between the Tm 3+ levels of the transition 1 G 4 ? 3 F 4 and we observed an increase of the emission intensity at the signal wavelength due to the stimulated emission. Transient positive optical gain around 3 cm À1 ($12 dB/cm) has been measured in Tm-Yb codoped fluoroindate glass during the first 400 ls.
Infrared-to-visible CW frequency upconversion in Er3+-doped fluoroindate glasses
Applied Physics Letters, 1996
We report on efficient frequency upconversion in Er 3ϩ -doped fluoroindate glasses. The process is observed under 1.48 m laser diode excitation and results in the generation of strong blue ͑ϳ407 nm͒, green ͑ϳ550 nm͒, and red ͑ϳ670 nm͒ radiation. The main mechanism that allows for upconversion appears to be the energy transfer among Er 3ϩ ions in excited states. The results illustrate the large potential of this new class of glasses for photonic applications.
Optical Components and Materials, 2004
Blue, green, red, and near-infrared upconversion luminescence in the wavelength region of 480-740 nm in Pr 3þ /Yb 3þ -codoped lead-cadmium-germanate glass under 980 nm diode laser excitation, is presented. Upconversion emission peaks around 485, 530, 610, 645, and 725 nm which were ascribed to the 3 P 0 -3 H J (J ¼ 4, 5, and 6), and 3 P 0 -3 F J (J ¼ 2, 3, and 4), transitions, respectively, were observed. The population of the praseodymium upper 3 P 0 emitting level was accomplished through a combination of groundstate absorption of Yb 3þ ions at the 2 F 7=2 , energy-transfer Yb 3þ ( 2 F 5=2 )-Pr 3þ ( 3 H 4 ), and excited-state absorption of Pr 3þ ions provoking the 1 G 4 -3 P 0 transition. The dependence of the upconversion luminescence upon the Yb 3þ -concentration and diode laser power, is also examined, in order to subsidize the proposed upconversion excitation mechanism.
Spectroscopic properties and upconversion mechanisms in Er3+-doped fluoroindate glasses
Physical Review B, 1996
Fluorindate glasses containing 1,2,3,4 ErF 3 mol % were prepared in a dry box under argon atmosphere. Absorption, Stokes luminescence ͑under visible and infrared excitation͒, the dependence of 4 S 3/2 , 4 I 11/2 , and 4 I 13/2 lifetimes with Er concentration, and upconversion under Ti-saphire laser excitation at ϭ790 nm were measured, mostly at Tϭ77 and 300 K. The upconversion results in a strong green emission and weaker blue and red emissions whose intensity obeys a power-law behavior Iϳ P n , where P is the infrared excitation power and nϭ1.6, 2.1, and 2.9 for the red, green, and blue emissions, respectively. The red emission exponent nϭ1.5 can be explained by a cross relaxation process. The green and blue emissions are due to excited state absorption ͑ESA͒ and energy transfer ͑ET͒ processes that predict a factor nϭ2 and nϭ3 for the green and blue emissions, respectively. From transient measurements we concluded that for lightly doped samples the green upconverted emission is originated due to both processes ESA and ET. However, for heavily doped samples ET is the dominant process.