3+ 3+ Upconversion luminescence properties of Yband Tm
codoped amorphous fluoride ZBLAN thin film prepared by
pulsed laser deposition 1,211115 He Chunfeng, Qin Guanshi, Zhao Dan, Chuai Xiaohong, Wang Lili, 1Qin Weiping
(1. State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and
Engineering, Jilin University, ChangChun 130012;
2. College of physics, Jilin University, ChangChun 130012)3+ 10 Abstract: This paper reports on the spectroscopic properties and energy transfer analysis of Yb3+ and Tmco-doped 55.98ZrF-28BaF-2.5LaF-4AlF-7NaF-2.5YbF-0.02TmFamorphous 423333
fluoride film prepared by pulsed laser deposition. This glass thin film has the potential application for integrated optical waveguide amplifier and laser. Ultraviolet and visible up-conversion emissions were observed under infrared excitation at 980 nm. In comparison with that of the target,
15 the upconversion emissions are enhanced greatly. The possible mechanism of the emissions was given.
Keywords: physicas; pulsed laser deposition; ZBLAN; film; upconversion
20 Over the past decade there has been a renewed interest in the spectroscopic properties of the
3+thulium (Tm) ion, particularly in application areas such as optical data storage, optical communications, color display, high power lasers, medicine and sensing. Of particular interest to
[1-4] this work is the application for all-solid short wavelength compact laser devices.The optical
thin films doping high refractive index dielectric materials with rare-earth (RE) ions for integrated
[5-13] 25 gain devices is useful for device miniaturization. In order to fabricate upconversion
wave-guide device on one substrates, pulsed laser deposition (PLD) is induced, which is a developed technique can deposit in gas environment and can successfully to grow
[14,15]multi-component thin films.
In this work ？ we report the upconversion emission properties of the
30 55.98ZrF-28BaF-2.5LaF-4AlF-7NaF-2.5YbF-0.02TmF(ZBLAN) amorphous fluoride film. 423333
With the excitation of 980 nm laser diode, ultra-violet, violet and visible emissions were observed. The mechanism of the emissions was given. Excited state absorption and energy transfer may be the efficient up-conversion mechanisms in this RE doped materials.
35 The following condition for depositing ZrF-BaF-LaF-AlF-NaF layers was employed in all 4233
cases: The light source for PLD is a pulsed Nd:YAG laser whose radiation wavelength is 1064 nm？ the pulse width is 10 ns and the repetition rate is 10 Hz. The laser beam, whose peak power
5 of 10W, was focused onto the target (55.98ZrF-28BaF-2.5LaF-4AlF-7NaF-2.5YbF- 42333
0.02TmFglass prepared by solid-state reaction) at an incidence angle of about 45? in air. The 3 240 laser spot at the target was ~3mm.The target-to-substrate (K9 glass) distance was kept at 15 mm
at room temperature. The duration of exposure of the target for the formation of the film is about
20 min. As shown in Fig.1.
60908031, 61077033 , 51072065？
Fig.1 Schematic diagram of the PLD setup
The film is amorphous. And the components of the film are the same as those of the target.
Upconversion luminescence spectra were recorded with a Hitachi F-4500 fluorescence
spectrophotometer which equipped with a 980 nm continuous wave diode laser as excitation
50 2 Results and discussion
Under 980 nm excitation, all samples with different intensity present intense upconversion
emissions at room temperature. Fig.2 shows the upconversion spectrum of visible light region
13recorded under different pump currents. Blue and green emission peaks from the D?Fand 24 13G?Htransitions were detected at approximately 451 nm and 474nm respectively. The red and 46
55 NIR emissions were observed to be centered at 646 nm and 803 nm, which were from the
1333G?Fand H?Htransitions respectively. The upconversion luminescence intensity reached 44 46
the maximum when the pump current was 0.75A. The possible reason may be the
saturation phenomenon of the upconversion luminescence at high excitated density. The
3+ 3+3+ unusually intense ultra violet (UV) emissions of Tmwere observed in ZBLAN: Yb/Tmfilms,
60 as shown in Fig.3.These UV emissions were observed to be centered at 291 nm, 347 nm and 361 131313nm, which were attributed to the I?H, I?Fand D?Htransitions, respectively. They 6664 26 3+ were all the characteristic emission lines of Tmions excited by the energy transfer (ET) form 3+ excited Ybions.  G.Qin et.al.explained why intense UV upconversion fluorescence can be observed in films. 65 The auther gave the most possible mechanism responsible for the enhancement of the UV
emission was the change of structure coupled with RE ions during PLD.
0.75A 3000 0.70A 0.65A
0400 500 600 700 800
Fig.2 the UC spectrum of visible light region recorded under different pump currents.
0 260 280 300 320 340 360 380 400
3+3+ 70 Fig.3 upconversion luminescence spectrum of ZBLAN: Yb/Tmfilm in the range of 260?400 nm under
980 nm excitation. 3+ 3+3+ 33The pump light excited only the Ybions in ZBLAN: Yb, Tmthin film, the H, Fand 52 13+ 3+3Glevels were populated by three successive ETs from Ybto Tm. The populated Flevel 4 2 33175 might non-radiative relax to Fand Hlevels producing 699 nm and 803 nm emissions. The G3 4 4 33level might radiatively depopulate to Hand Flevels, which caused 474 nm and 646 nm 6 4 13+ 3+ emissions. The Dlevel of Tmcannot be populated by the fourth photon energy from Ybvia 2 1-1ET to the Glevel due to the large energy mismatch (about 3500cm) between them. So the cross 4 33313+ relaxation process of F+ H?H+Dbetween Tmions might alternatively play an important 246 2 11380 role in populating the Dlevel. The radiative transitions of the populated Dlevel to the Fand 2 2 3 33+ Hlevels caused 361 nm and 451 nm emissions, respectively. In addition, the Tmions in the 4 11Dstate might be excited to the higher Ilevel via another ET process and then caused 291 nm 2 6 3+ 3+ and 347 nm emissions at the same time. Fig.4 shows energy level diagrams of Tmand Ybions.
40 3 -1 X10 cm 3 3 P , P 2 1 3 1 P , I0 6 35 30 1 D 2
1 G 4 2 0 3 3 F , F 2 15 3 3 2 H 4 F 5/ 2 10 3 H 5 5 3 F 4 2 F 7/ 2 3 H 6 0 3+ 3+ Yb Tm 3+3+ 85 Fig.4 Energy level diagrams of Yb, and Tmions, and possible upconversion processes.
3+3+ In conclusion, Yb/Tmcodoped ZBLAN films were successfully received using pulsed
laser deposition method at low temperature. Under 980 nm excitation, 291 nm UV upconversion
3+ 90 emission of Tmions was observed in the Yb–Tm codoped ZBLAN film for the first time. The
intense UV upconversion film has the potential in building short-wavelength waveguide lasers.
This work was supported by the National Natural Science Foundation of China (NNSFC)
(Grants 61108023, 60908031, 61077033 and 51072065) and the Doctor project for young teachers
95 of Ministry of Education (grant 20110061120056).
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PLD 法制备的铥镱共掺 ZBLAN 薄膜的上转换特性
研究 1,211111 120 何春凤？秦冠仕？赵丹？揣晓红？王丽丽？秦伟平
；1. 吉林大学电子科学与工程学院集成光电子国家重点实验室？长春 130012！
2. 吉林大学物理学院？长春 130012？ 3+3+ 摘要 ， 本文采 用 PLD 法成 功制备 了 Yb/Tm共 掺 杂 的 55.98ZrF -28BaF -2.5LaF -4 2 3 -7NaF-2.5YbF-0.02TmF薄膜。这种 ZBLAN 玻璃薄膜在波导放大器和激光器小型化的方 4AlF333
125 面具有潜在的应用价值。测量了其在 980 nm 激光激发下的上转换发光光谱？得到了较强的 361 nm , 347nm 和 291 nm 的紫外上转换发光,以及中心位于 451 nm, 474 nm, 646 nm 和 804 nm 的上转换荧光发射.通过对光谱性质的分析得出了此材料中体系的上转换发光的机 理。 关键词，电子物理学！脉冲激光沉积！ZBLAN！薄膜！上转换