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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 15, Iss. 11 — May. 28, 2007
  • pp: 6883–6888
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Multi-photon absorption upconversion luminescence of a Tb3+-doped glass excited by an infrared femtosecond laser

Songmin Zhang, Bin Zhu, Shifeng Zhou, Shiqing Xu, and Jianrong Qiu  »View Author Affiliations


Optics Express, Vol. 15, Issue 11, pp. 6883-6888 (2007)
http://dx.doi.org/10.1364/OE.15.006883


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Abstract

In this paper we presents the near infrared to visible upconversion luminescence in a Tb3+-doped ZnO-B2O3-SiO2 glass excited with 800nm femtosecond laser irradiation. The upconversion luminescence is attributed to 5D4 to 7F j (j=3, 4, 5, 6) transitions of Tb3+.The relationship between upconversion luminescence intensity and the pump power indicates that a three-photon simultaneous absorption process is dominant in this upconversion luminescence. The calculated value of the three-photon absorption cross section σ3 of the glass is 1.832×10-81cm6s2. Also, three-dimensional display is demonstrated based on the multiphoton absorption upconversion luminescence for the first time.

© 2007 Optical Society of America

1. Introduction

In this paper, we have been reported the upconversion luminescence in a Tb3+-doped ZnO-B2O3-SiO2 glass under femtosecond laser irradiation. We have selected this glass because of its bright luminescence when excited with ultraviolet source at 267nm (which is one third of the wavelength of Ti: sapphire femtosecond laser) compared with other Tb3+-doped oxide glasses. In addition, it is important to study the multiphoton absorption upconversion luminescence in glass for the realization of three dimensional displays because glass can be fabricated as a plate with large size. The value of the three-photon absorption cross section is calculated. We also demonstrated the three-dimensional display based on multiphoton absorption upconversion luminescence.

2. Experimental

The chemical composition of the glass sample prepared was 65ZnO-20B2O3-15SiO2-0.5Tb2O3 (mol %). Reagent grade ZnO, B2O3, SiO2 and Tb4O7 were used as the starting materials. Tb3+ was doped as the luminescent center. Approximately 30g batch was mixed and melted in Pt crucibles in an electronic furnace at 1300 °C for 2 h in an ambient atmosphere. The melt was then quenched to obtain transparent glass. The glass was cut and polished for optical measurements.

A regeneratively amplified 800nm Ti: sapphire laser system with 1 kHz repetition rate and approximately 120fs pulse duration was used as an irradiation source. The laser beam was focused onto samples through optical lens in order to obtain higher power density. The focal point can be monitored by a confocal microscope system linked to a charge coupled device system when objective lens is used. The position of the focal point was on the interior of the glass. By choosing appropriate objective lens or optical lens and adjusting the power density of laser beam, we can control the spot size below several microns. The fluorescence spectra excited with femtosecond laser were measured from the side of the glass sample by a spectrophotometer of ZOLIX SBP300. The scanning rate of this spectrophotometer was 100nm/min.The photoluminescence spectra were measured on a Hitachi F-4500 fluorescence spectrophotometer with a Xe lamp as an excitation source. In addition, the absorption spectrum was measured on Hitachi UV-4100 spectrophotometer. All the measurements were carried out at room temperature.

3. Results and discussion

An intense green emission has been observed near the focal point during the femtosecond laser irradiation. Fig. 1 presents the emission spectra of the glass irradiated with the femtosecond laser focused by an optical lens with focal length of 10cm.and excited with 267nm from a xenon lamp. This spectra consist of four emission peaks at about 490nm, 545nm, 580nm and 620nm wavelengths and are assigned to the transitions from 5D4 to 7Fj (j=3, 4, 5, 6) of Tb3+ions, respectively. The emission spectra appear to be similar for both excitation wavelengths. The excitation spectrum of the glass is also shown in Fig. 1. All the peaks can be assigned to the 4f-4f transitions of Tb3+ and the strongest excitation peak at 382nm could be assigned to the 7F05D3 transition of Tb3+[15

15. B. V. Shulgin, K. Taylor. A. Hoaksey, and R. Hunt, “Optical characteristics of Tb3+ ions in soda glass,” J. Phys. C: Solid State Phys. 5, 1716–26(1972). [CrossRef]

]. The inset of Fig. 1 is the photograph of emission state of the glass irradiated with the focused femtosecond laser. Highly localized green emission is observed in the glass.

Fig. 1. Emission spectra of glass under 800nm femtosecond laser irradiation (a) with 267nm excitation (b) excitation spectrum when the emission at 545nm is monitored(c). The inset shows the emission state of the glass sample irradiated by the focused femtosecond laser. The arrow indicates the propagation direction of the laser beam.

As far as the multiphoton process is concerned, the relationship between the emission intensity and the exciting pump power can be expressed as follows:

IPn
(1)

where I is the integrated intensity of the upconversion luminescence, P is the pump power of the femtosecond laser, and n is the photon number. The n can be experimentally determined. Fig. 2 presents a series of luminescence spectra by changing the excitation pump power of femtosecond laser at a fixed focused point. The number of photons n can be determined from the slope coefficient of the linear fitted line by plotting the logarithmic transformation of the pumping power and fluorescence intensity. Fig. 3 presents the relationship of the femtosecond laser pumping power and luminescent intensity of the glass. The slope of the logarithmic fitted line is about 3.093 and the correlation coefficient is 0.998, which indicates that the upconversion process is a three-photon excitation process.

Fig. 2. Emission spectra of the glass under 800nm femtosecond laser irradiation with different pump powers.
Fig. 3. Upconversion luminescence intensity of the 5D4- 7F5 transition of Tb3+ ions in the glass as a function of the femtosecond laser pump power.

The absorption spectrum of the Tb3+ doped ZnO-B2O3-SiO2 glass is shown in Fig. 4.This spectrum has shown a strong absorption band at about 267nm,which could be due to 4f-5d transition of Tb3+ in the ZnO-B2O3-SiO2 glass.

Fig. 4. Absorption spectrum of the glass

It is well known that upconversion processes involve mechanisms of excited-state absorption, energy transfer, cooperative upconversion and photon avalanche [16

16. J. Chivian, W. Case, and D. Eden, “The photon avalanche: A new phenomenon in Pr3+ -based infrared quantum counters,” Appl. Phys. Lett. 35, 124–125 (1979). [CrossRef]

, 17

17. F. Auzel, “Upconversion and anti-stokes processes with f and d ions in solids,” Chem. Rev. 104, 139–173 (2004). [CrossRef] [PubMed]

]. The mechanisms of energy transfer, excited-state absorption and cooperative upconversion could be considered only when the energy separation between the intermediate state and the excited state correspond to the photon energy of pumping laser. This means the glass should have an absorption band near 800nm, if one of them dominated the upconversion processes. However, there is no obvious absorption band near 800nm for the studied glass (see Fig. 4). Therefore, the multiphoton absorption upconversion luminescence process can not be accounted for these mechanisms. The photon avalanche as a mechanism of the upconversion can also be ruled out because there is no intermediate metastable state between the ground state and the excited state. Moreover, the upconversion luminescence is not a femtosecond laser induced defect-assisted process because there was no detectable change in the absorption of the glass in the 200-800nm wavelength range, after the femtosecond laser irradiation under our experimental conditions. Another upconversion mechanism is that the Tb3+ absorbs two-photons simultaneously to a level first and then absorbs the last photon. In this case, the Tb3+ doped ZnO-B2O3-SiO2 glass should have an intermediate state corresponding to absorption at 400nm. However, the Tb3+ions are lack of intermediate state between the ground states and the excited states and thus there is no absorption band at 400nm (see Fig.4).

Therefore, the only upconversion mechanism is a three-photon simultaneous absorption process. The active ions have excited states that can simultaneously absorb three pumping photons and also the pumping photon density is high that leads to efficient three-photon simultaneous absorption. Femtosecond laser used in our experiment could obtain high pumping photon density for efficient three-photon simultaneous absorption. In our study, the glass has an absorption band at about 267nm, which implies that the energy of three photons of infrared pumping laser can be efficiently and simultaneously absorbed. Pumping the Tb3+ by using focused 800nm femtosecond laser causes population of electrons in the excited state, the excited electrons nonradiatively relaxes to the 5D4 state, and then radiatively return to the 7Fj (j=3, 4, 5, 6) states, leading to the characteristic green emission of Tb3+.

We have also measured the three-photon absorption coefficient of Tb3+-doped ZnO-B2O3-SiO2 glass with an excitation wavelength 800nm by using the intensity-dependent transmission measurement. The transmitted intensity of the laser beam as a function of incident intensity can be expressed as [18

18. F. E. Hernandez, K.D. Belfield, and I. Cohanoschi, “Three-photon absorption enhancement in a symmetrical charge transfer fluorene derivative,” Chem. Phys. Lett. 391, 22–26(2004). [CrossRef]

]:

I(z)=I0(1+2γzI02)1/2
(2)

where γ is the three-photon absorption coefficient of Tb3+-doped ZnO-B2O3-SiO2 glass, z is the optical propagation path and I0 is the incident intensity of excitation beam. Equation (1) is adequate for a pulsed beam with a rectangular temporal profile. In our case the incident pulses have a quasi-Gaussian temporal profile. The measured transmitted intensity as a function of incident intensity is shown in Fig 5. The best-fit parameter of γ is 8.24×10- 24cm3W-2 .

Fig.5. Transmitted intensity vs excitation intensity for Tb3+-doped ZnO-B2O3-SiO2 glass.

Based on the known γ value of the measured glass, the absorption cross section for the Tb3+-doped ZnO-B2O3-SiO2 glass is obtained as [18

18. F. E. Hernandez, K.D. Belfield, and I. Cohanoschi, “Three-photon absorption enhancement in a symmetrical charge transfer fluorene derivative,” Chem. Phys. Lett. 391, 22–26(2004). [CrossRef]

]

σ3=(γNAd0)(hcλ)2
(3)

where NA is the Avagadro constant, d0 is the concentration of doped Tb3+ ions(moles per cm3), and (hc/λ) is the energy of an incident photon at 800nm.The calculated value of the three-photon cross section of Tb3+-doped ZnO-B2O3-SiO2 glass σ3=1.832×10-81cm6s2.

Fig. 6. Photograph of a simple mark through scanning the femtosecond laser into the glass.

As the Tb3+-doped glass has shown highly localized green emission when excited with focused femtosecond laser, this observed phenomenon can be used for three dimensional solid state displays. Fig. 6 presents the photograph of a simple mark through scanning the 800nm femtosecond laser into the Tb3+-doped glass at a scanning rate of 300pixes/s via computer controlled scanning type galvanometer. The femtosecond laser beam was focused onto the the glass by a lens with focal length of 2cm. We have observed a three dimensional green elliposoidal shape image with 13 horizontal lines inside the glass. It should be possible to realize three-dimensional, solid state, three color display based on multiphoton absorption upconversion luminescence if we could design and control the combination of doping species and microstructure of the glass.

4. Conclusions

In summary, it is concluded that an intense green upconversion luminescence in the Tb3+ doped ZnO-B2O3-SiO2 glass has been observed under infrared femtosecond laser irradiation. The upconversion luminescence is a three photon excitation process from the relationship between the fluorescence intensity and the pump power where the upconversion mechanism is a three-photon simultaneous absorption process. The value of the three-photon absorption cross section σ3 of Tb3+-doped ZnO-B2O3-SiO2 glass is about 1.832×10-81cm6s2. We also demonstrated the three dimension display based on multiphoton upconversion luminescence. There results have potential applications in the three-color, solid state, three dimensional display systems.

Acknowledgements

This work was financially supported by National Natural Science Foundation of China (Grant No.50672087) and High Technology Research and Development Program of China (G20060914), and was partially supported by the China Postdoctoral Science Foundation (2005038020).

References and links

1.

G. S. He, P. P. Markowicz, T. C. Lin, and P. N. Prasad, “Observation of stimulated emission by direct three-photon excitation,” Nature 415, 767–770 (2002). [CrossRef] [PubMed]

2.

G. S. He, J. M. Dai, T.C. Lin, P. P. Markowicz, and P. N. Prasad, “Ultrashort 1.5-mu m laser excited upconverted stimulated emission based on simultaneous three-photon absorption ,” Opt. Lett. 28, 719–721 (2003). [CrossRef] [PubMed]

3.

S. K. Sundaram and E. Mazur, “Inducing and probing non-thermal transitions in semiconductors using femtosecond laser pulses,”Nat. Mater. 1, 217–224 (2002). [CrossRef]

4.

K. Wong, W. Kwok, W. Wong, D. Phillips, and K. Cheah, “Green and red three-photon upconversion from polymeric lanthanide(III) complexes,” Angew. Chem. Int. Ed. 35, 4659–62 (2004) [CrossRef]

5.

E. Downing, L. Hesselink, J. Ralston, and R. Macfarlane, “A three color, Solid state, Three-Dimensional display,” Science 273, 1185–89 (1996). [CrossRef]

6.

D. A. Parthenopoulos and P. M. Rentzepis, “Three-Dimensional Optical Storage Memory,” Science 245, 843–845 (1989). [CrossRef] [PubMed]

7.

S. Juodkazis, A.V. Rode, E.G. Gamaly, S. MatsuoS, and H. Misawa, “Recording and reading of three-dimensional optical memory in glasses,” Appl.Phys.B: Lasers Opt. 77,361–368(2003). [CrossRef]

8.

D. Mihailovic, D. Dvorsek, V. V. Kabanov, J. Demsar, L. Forro, and H. Berger, “Femtosecond data storage, processing, and search using collective excitations of a macroscopic quantum state,” Appl. Phys. Lett. 80, 871–873 (2002). [CrossRef]

9.

J. Qiu, P. Kazansky, J. Si, K. Miura, T. Mitsuyu, K. Hirao, and A. L. Gaeta, “Memorized polarization-dependent light scattering in rare-earth-ion-doped glass,” Appl. Phys. Lett. 77, 1940–42 (2000). [CrossRef]

10.

H. You and M. Nogami, “Three-photon-excited fluorescence of Al2O3-SiO2 glass containing Eu3+ ions by femtosecond laser irradiation,” Appl. Phys. Lett. 84, 2076–78 (2004). [CrossRef]

11.

Y. Shimotsuma, P.G. Kazansky, J. Qiu, and K. Hirao,”Self organized nanogratings in Glass irradiated by ultrashort light pulses”,Phys.Rev.Lett. 91,247405(2003). [CrossRef] [PubMed]

12.

J. Qiu, K. Miura, H. Inouye, Y. Kondo, T. Mitsuyu, and T, K. Hirao, “Femtosecond laser-induced three-dimensional bright and long-lasting phosphorescence inside calcium aluminosilicate glasses doped with rare earth ions,” Appl. Phys. Lett. 73, 1763–65 (1998). [CrossRef]

13.

M. Watanabe, S. Juodkazis, H. Sun, S. Matsuo, and H. Misawa “Luminescence and defect formation by visible and near-infrared irradiation of vitreous silica,” Phys. Rev. B 60, 9959–64 (1999). [CrossRef]

14.

J. Qiu, K. Miura, T. Suzuki, T. Mitsuyu, and K. Hirao “Permanent photoreduction of Sm3+ to Sm2+ inside a sodium aluminoborate glass by an infrared femtosecond pulsed laser,” Appl. Phys. Lett. 74, 10–12 (1999). [CrossRef]

15.

B. V. Shulgin, K. Taylor. A. Hoaksey, and R. Hunt, “Optical characteristics of Tb3+ ions in soda glass,” J. Phys. C: Solid State Phys. 5, 1716–26(1972). [CrossRef]

16.

J. Chivian, W. Case, and D. Eden, “The photon avalanche: A new phenomenon in Pr3+ -based infrared quantum counters,” Appl. Phys. Lett. 35, 124–125 (1979). [CrossRef]

17.

F. Auzel, “Upconversion and anti-stokes processes with f and d ions in solids,” Chem. Rev. 104, 139–173 (2004). [CrossRef] [PubMed]

18.

F. E. Hernandez, K.D. Belfield, and I. Cohanoschi, “Three-photon absorption enhancement in a symmetrical charge transfer fluorene derivative,” Chem. Phys. Lett. 391, 22–26(2004). [CrossRef]

OCIS Codes
(120.2040) Instrumentation, measurement, and metrology : Displays
(160.2750) Materials : Glass and other amorphous materials
(190.4180) Nonlinear optics : Multiphoton processes
(320.7090) Ultrafast optics : Ultrafast lasers

ToC Category:
Nonlinear Optics

History
Original Manuscript: February 27, 2007
Revised Manuscript: May 7, 2007
Manuscript Accepted: May 9, 2007
Published: May 18, 2007

Citation
Songmin Zhang, Bin Zhu, Shifeng Zhou, Shiqing Xu, and Jianrong Qiu, "Multi-photon absorption upconversion luminescence of a Tb3+-doped glass excited by an infrared femtosecond laser," Opt. Express 15, 6883-6888 (2007)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-15-11-6883


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References

  1. G. S. He, P. P. Markowicz, T. C. Lin, P. N. Prasad, "Observation of stimulated emission by direct three-photon excitation," Nature 415, 767-770 (2002). [CrossRef] [PubMed]
  2. G. S. He, J. M. Dai, T.C. Lin, P. P. Markowicz, P. N. Prasad, "Ultrashort 1.5-mu m laser excited upconverted stimulated emission based on simultaneous three-photon absorption, " Opt. Lett. 28, 719-721 (2003). [CrossRef] [PubMed]
  3. S. K. Sundaram and E. Mazur, "Inducing and probing non-thermal transitions in semiconductors using femtosecond laser pulses,"Nat. Mater. 1, 217-224 (2002). [CrossRef]
  4. K. Wong, W. Kwok, W. Wong, D. Phillips, and K. Cheah, "Green and red three-photon upconversion from polymeric lanthanide(III) complexes," Angew. Chem. Int. Ed. 35, 4659-4662 (2004) [CrossRef]
  5. E. Downing, L. Hesselink, J. Ralston, and R. Macfarlane, "A three color, Solid state, Three-Dimensional display," Science 273, 1185-1189 (1996). [CrossRef]
  6. D. A. Parthenopoulos and P. M. Rentzepis, "Three-dimensional optical storage memory," Science 245, 843-845 (1989). [CrossRef] [PubMed]
  7. S. Juodkazis, A. V. Rode, E. G. Gamaly, S. MatsuoS, H. Misawa, "Recording and reading of three-dimensional optical memory in glasses," Appl. Phys. B: Lasers Opt. 77, 361-368(2003). [CrossRef]
  8. D. Mihailovic, D. Dvorsek, V. V. Kabanov, J. Demsar, L. Forro, H. Berger, "Femtosecond data storage, processing, and search using collective excitations of a macroscopic quantum state," Appl. Phys. Lett. 80, 871-873 (2002). [CrossRef]
  9. J. Qiu, P. Kazansky, J. Si, K. Miura, T. Mitsuyu, K. Hirao, A. L. Gaeta, "Memorized polarization-dependent light scattering in rare-earth-ion-doped glass," Appl. Phys. Lett. 77, 1940-1942 (2000). [CrossRef]
  10. H. You and M. Nogami, "Three-photon-excited fluorescence of Al2O3-SiO2 glass containing Eu3+ ions by femtosecond laser irradiation," Appl. Phys. Lett. 84, 2076-78 (2004). [CrossRef]
  11. Y. Shimotsuma, P. G. Kazansky, J. Qiu, and K. Hirao, "Self organized nanogratings in glass irradiated by ultrashort light pulses," Phys. Rev. Lett. 91, 247405 (2003). [CrossRef] [PubMed]
  12. J. Qiu, K. Miura, H. Inouye, Y. Kondo, T. Mitsuyu T, K. Hirao, "Femtosecond laser-induced three-dimensional bright and long-lasting phosphorescence inside calcium aluminosilicate glasses doped with rare earth ions," Appl. Phys. Lett. 73, 1763-1765 (1998). [CrossRef]
  13. M. Watanabe, S. Juodkazis, H. Sun, S. Matsuo, H. Misawa "Luminescence and defect formation by visible and near-infrared irradiation of vitreous silica," Phys. Rev. B 60, 9959-9964 (1999). [CrossRef]
  14. J. Qiu, K. Miura, T. Suzuki, T. Mitsuyu, K. Hirao "Permanent photoreduction of Sm3+ to Sm2+ inside a sodium aluminoborate glass by an infrared femtosecond pulsed laser," Appl. Phys. Lett. 74, 10-12 (1999). [CrossRef]
  15. B. V. Shulgin, K. Taylor. A. Hoaksey, and R. Hunt, "Optical characteristics of Tb3 + ions in soda glass," J. Phys. C: Solid State Phys. 5, 1716-1726 (1972). [CrossRef]
  16. J. Chivian, W. Case, and D. Eden, "The photon avalanche: A new phenomenon in Pr3+ -based infrared quantum counters," Appl. Phys. Lett. 35, 124-125 (1979). [CrossRef]
  17. F. Auzel, "Upconversion and anti-stokes processes with f and d ions in solids," Chem. Rev. 104, 139-173 (2004). [CrossRef] [PubMed]
  18. F. E. Hernandez, K. D. Belfield, and I. Cohanoschi, "Three-photon absorption enhancement in a symmetrical charge transfer fluorene derivative," Chem. Phys. Lett. 391, 22-26 (2004). [CrossRef]

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