OSA's Digital Library

Optics Express

Optics Express

  • Editor: Michael Duncan
  • Vol. 13, Iss. 6 — Mar. 21, 2005
  • pp: 2040–2046
« Show journal navigation

Upconversion effect on fluorescence quantum efficiency and heat generation in Nd3+-doped materials

Carlos Jacinto, Samuel L. Oliveira, Tomaz Catunda, Acácio A. Andrade, John D. Myers, and Michael J. Myers  »View Author Affiliations


Optics Express, Vol. 13, Issue 6, pp. 2040-2046 (2005)
http://dx.doi.org/10.1364/OPEX.13.002040


View Full Text Article

Acrobat PDF (121 KB)





Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations

Abstract

The thermal lens technique was carried out to experimentally determine the influence of the energy transfer upconversion (ETU) processes on fluorescence quantum efficiency (η) in Nd3+-doped materials. The samples with high Nd3+concentration present a considerable reduction in η with the increasing excitation power due to the efficient ETU processes. Besides, the energy migration was identified as the mechanism responsible for the upconversion losses. In addition, it was verified that the critical inversion density is not concentration independent, as previously stated, but it decreases with the Nd concentration. Our results point out the approach based on TL technique as a valuable alternative because of its sensitivity allowing the measurements to be performed in a pump power regime that avoids damages in the investigated material.

© 2005 Optical Society of America

1. Introduction

Intense diode pumping of active materials doped with Nd3+ is a common approach to produce efficient, reliable, and compact high-power laser systems. The high efficiency of diode pumping can develop large population inversion densities in the 4F3/2 upper level that can be lased at either ~1.06 or ~1.3 µm. The upper-state fluorescence quantum efficiency (η) is an important parameter for engineering such lasers since it affects the achievable energy storage density for a given pumping scheme and ultimately determines the output energy of the laser. The intense-pumping regime brings new effects into prominence, which may change the system parameters, required for optimum performance. Some of these effects are upconversion losses [1

1. S. A. Payne, G. D. Wilke, L. K. Smith, and W. F. Krupke, “Auger upconversion losses in Nd-doped laser glasses,” Opt. Commun. 111, 263–268 (1994). [CrossRef]

11

11. D. C. Brown, “Heat, fluorescence, and stimulated-emission power densities and fractions in Nd:YAG,” IEEE J. Quantum Electron. 34, 560–572 (1998). [CrossRef]

].

The aim of this work is the determination of upconversion parameter (γ) and its effect on η of Nd-doped materials using the thermal lens (TL) technique.

2. Theoretical background and experiment

The dynamics of 4F3/2 level considering the ETU mechanisms can be described by:

dNedt=σIhνexNgNeτγNe2
(1)

where Ne, Ng , and Nt≈Ne+Ng are the excited metastable state (4F3/2), ground state (4I9/2), and total population, respectively. σ is the absorption cross-section at the pump photon energy ex , I is the pump intensity, and γ(cm3/s) is the upconversion parameter. In the low pump regime (γNe<<τ-1 ) the fluorescence decay is basically exponential with the measured decay rate (τ-1 ) given mainly by the sum of radiative (τrad1 ), multiphonon, and cross relaxation decay rates. The ETU mechanisms causes an additional decay rate Wup=γNe . Since Wup increases with Ne , it results in nonexponential fluorescence decay.

In the absence of ETU, i.e., in the regime of very low pump power, the fluorescence quantum efficiency of a given level is given by η?=τ/τrad (the ratio between its radiative and total rates). As the pump rate increases and consequently Ne , ETU becomes significant and the total decay rate can be written as Wt-1+γNe. In this case η is given by [3

3. V. Pilla, T. Catunda, H. P. Jenssen, and A. Cassanho, “Fluorescence quantum efficiency measurements in the presence of Auger upconversion by the thermal lens method,” Opt. Lett. 28, 239–241 (2003). [CrossRef] [PubMed]

]:

η=ηo1+βne
(2)

φ=1ηνemνex,
(3)

since part of the absorbed excitation photon energy (ex ) is converted into heat and the remaining energy is converted into fluorescence, generating a photon with average energy hνem 〉. Eq. (2) shows that as ne is increased by the excitation power, η is reduced due to the factor 1+β.ne associated with ETU. Therefore, by measuring the η dependence on the excitation power, it is possible to evaluate the influence of ETU on η and φ.

In the TL experiment, the sample is exposed to an excitation laser beam with a Gaussian intensity profile. A fraction of absorbed energy is converted into heat, generating a radial temperature profile ΔT(r,t). Since the refractive index of the sample changes with temperature, a refractive index gradient is produced, creating a lens-like optical element-the so-called TL. The presence of such TL is detected by its effect on the propagation of a probe beam passing through the sample. The temporal evolution of the on-axis probe beam intensity is measured in the far field using a circular aperture in front of a photodiode detector [12

12. S. M. Lima, A. A. Andrade, R. Lebullenger, A. C. Hernandes, T. Catunda, and M. L. Baesso, “Multiwavelength thermal lens determination of fluorescence quantum efficiency of solids: Application to Nd3+-doped fluoride glass,” Appl. Phys. Lett. 78(21), 3220–3222 (2001). [CrossRef]

16

16. M. L. Baesso, J. Shen, and R. D. Snook, “Mode-mismatched thermal lens determination of temperature coefficient of optical path length in soda lime glass at different wavelengths,” J. Appl. Phys. 75(8), 3732–3737 (1994). [CrossRef]

]. The TL signal is proportional to the phase difference, θ, of the probe beam between the beam center r=0 and r=√2we , induced by the TL [16

16. M. L. Baesso, J. Shen, and R. D. Snook, “Mode-mismatched thermal lens determination of temperature coefficient of optical path length in soda lime glass at different wavelengths,” J. Appl. Phys. 75(8), 3732–3737 (1994). [CrossRef]

]. Here, r is the radial distance from the beam center in the sample. Since θ is proportional to the absorbed power of the excitation beam, Pabs , it is convenient to use the normalized parameter:

Θ=θPabs=φKλpdsdT
(4)

in which λp is the probe beam wavelength, K=ρ.c.D is the thermal conductivity, ρ is the density, c is the specific heat, D is the thermal diffusivity, and ds/dT is the temperature coefficient of the optical path length. More details can be found in references [12

12. S. M. Lima, A. A. Andrade, R. Lebullenger, A. C. Hernandes, T. Catunda, and M. L. Baesso, “Multiwavelength thermal lens determination of fluorescence quantum efficiency of solids: Application to Nd3+-doped fluoride glass,” Appl. Phys. Lett. 78(21), 3220–3222 (2001). [CrossRef]

16

16. M. L. Baesso, J. Shen, and R. D. Snook, “Mode-mismatched thermal lens determination of temperature coefficient of optical path length in soda lime glass at different wavelengths,” J. Appl. Phys. 75(8), 3732–3737 (1994). [CrossRef]

].

Considering the ETU effect on η, the expression for Θ becomes (see Eqs. 24):

Θ=C[1(ηo1+βne)νemνex]
(5)

where C=(p )-1 ds/dT. A closed expression for ne can be obtained in steady state regime from Eq. (1). It is convenient to express the power dependence of ne through the saturation parameter S=I/Is , in which Is=hνex/στ is the saturation intensity and I is the excitation intensity. Therefore, Eq. (5) allows the determination of the β parameter and thus of γ, by means of a fitting procedure of Θ as a function of the S parameter.

The TL measurements were performed in the dual beam mode-mismatched configuration. A He:Ne laser at 632.8nm was used as probe beam and a Ti:sapphire as excitation beam. The Ti:sapphire laser was tuned in resonance with the Nd3+ (4F5/2+2H9/2) level (~800nm), which decay nonradiatively, pumping the 4F3/2 metastable state. The TL measurements were recorded in the transient regime, where the parameters θ and tc=we2/4D (TL formation characteristic time) were obtained from transients curves through theoretical fit using the TL equation. Details of experimental procedure can be found elsewhere [13

13. S. M. Lima, J. A. Sampaio, T. Catunda, A. C. Bento, C. M. Miranda, and M. L. Baesso, “Mode-mismatched thermal lens spectrometry for thermo-optical properties measurement in optical glasses: a review,” J. Non-Cryst. Solids 273, 215–227 (2000). [CrossRef]

,16

16. M. L. Baesso, J. Shen, and R. D. Snook, “Mode-mismatched thermal lens determination of temperature coefficient of optical path length in soda lime glass at different wavelengths,” J. Appl. Phys. 75(8), 3732–3737 (1994). [CrossRef]

]. The study was performed in a Nd:YLF crystal and three sets of glasses: Phosphate (Q-98), Fluoroindate (PGIZCa), and Fluorozirconate (ZBLAN) with different Nd concentrations. The glass composition of PGIZCa and ZBLAN glasses were described previously [12

12. S. M. Lima, A. A. Andrade, R. Lebullenger, A. C. Hernandes, T. Catunda, and M. L. Baesso, “Multiwavelength thermal lens determination of fluorescence quantum efficiency of solids: Application to Nd3+-doped fluoride glass,” Appl. Phys. Lett. 78(21), 3220–3222 (2001). [CrossRef]

,13

13. S. M. Lima, J. A. Sampaio, T. Catunda, A. C. Bento, C. M. Miranda, and M. L. Baesso, “Mode-mismatched thermal lens spectrometry for thermo-optical properties measurement in optical glasses: a review,” J. Non-Cryst. Solids 273, 215–227 (2000). [CrossRef]

,15

15. C. Jacinto, S. L. Oliveira, L. A. O. Nunes, J. D. Myers, M. J. Myers, and T. Catunda, “Normalized lifetimes thermal lens method for determination of luminescence quantum efficiency and thermo-optical coefficients: Application to Nd3+-doped glasses,” (submitted).

]. The phosphate glasses were manufactured by Kigre Inc.

3. Results and discussion

Figure 2(a) depicts the concentration dependence of γ values, calculated from β(Nt) and τ(Nt). It is interesting to compare the γ values determined by TL technique and those obtained from transient emission measurements reported elsewhere. For instance, for a ZBLAN sample with Nt =2.5x1020 cm-3, Payne et al. [1

1. S. A. Payne, G. D. Wilke, L. K. Smith, and W. F. Krupke, “Auger upconversion losses in Nd-doped laser glasses,” Opt. Commun. 111, 263–268 (1994). [CrossRef]

] obtained γ=(4.6±1.4)x10-17cm3/s. For this same concentration, we estimate γ=(6.0±0.5)x10-17cm3/s from our data. It is worth noting that, in order to obtain reasonable accuracy (error ~30%), the measurements of Ref. [1

1. S. A. Payne, G. D. Wilke, L. K. Smith, and W. F. Krupke, “Auger upconversion losses in Nd-doped laser glasses,” Opt. Commun. 111, 263–268 (1994). [CrossRef]

] were performed at high excitation levels (βS≈0.63), near the damage threshold of the samples. In our experiments, γ was determined with higher accuracy (error~10%) with much lower excitation levels, corresponding to the βS in the range of 0.015-0.06. For YLF doped with 2.0x1020 ions/cm3 of Nd3+, Guyot et al. [7

7. Y. Guyot, H. Manaa, J. Y. Rivoire, R. Moncorgé, N. Garnier, E. Descroix, M. Bon, and P. Laporte, “Excited-state-absorption and upconversion studies of Nd3+-doped single crystals Y3Al5O12, YLiF4, and LaMgAl11O19,” Phys. Rev. B 51, 784–798 (1995). [CrossRef]

] have achieved γ=(1.7±1.0) x10-16 cm3/s. We achieved γ=(1.9±0.2)x10-16 cm3/s for an YLF crystal with 1.7x1020 ions/cm3.

Fig. 1. (a) TL amplitude, θ; (b) θ normalized by the absorbed power, Θ and (c) η normalized by ηo , versus excitation parameter S=I/Is at λex=801.6 nm for phosphate Q-98 glasses doped with 1.1 (closed circles), 3.3 (closed squares), 6.7 (open circles), and 10.3 (open squares) x1020 ions/cm3 of Nd3+. The lines in (b) represent the theoretical fit of experimental data.

Table 1. β parameter for Phosphate (Q-98), Fluoroindate (PGIZCa), and Fluorozirconate (ZBLAN) glasses and Nd:YLF crystal. The τ and ηo values were gathered from refs. [12,13,15].

table-icon
View This Table

We will now analyze the physical mechanisms involved in ETU. The upconversion processes involve static transfer (Förster-Dexter-“FD” model) and migration-assisted energy transfer (Burstein-“B” model) [1

1. S. A. Payne, G. D. Wilke, L. K. Smith, and W. F. Krupke, “Auger upconversion losses in Nd-doped laser glasses,” Opt. Commun. 111, 263–268 (1994). [CrossRef]

,2

2. J. L. Doualan, C. Maunier, D. Descamps, J. Landais, and R. Moncorgé, “Excited-state absorption and up-conversion losses in the Nd-doped glasses for high-power lasers,” Phys. Rev. B 62, 4459–4463 (2000); (and references therein). [CrossRef]

]. In the FD theory the initially excited Nd ions remain fixed in space, in other words, the donor excitation is transferred to an acceptor directly. In the B model, the excitation migrates over donors before it reaches an acceptor, from where energy can be transferred to acceptors in the most efficient way, so the migration mechanism causes an enhancement of the energy transfer to acceptors. The total upconversion rate is given by:

Wup=WFD+WB=(γFD+γB)neNt
(6)

where γFD =2(4/3)2 π 3(RupFD )6 Nerad and γB=2π(2π/3)5/2(RupB )3(Rmig )3 Ngrad . Rup is called the critical radius for Auger upconversion and Rmig is the critical radius for the energy migration mechanism [1

1. S. A. Payne, G. D. Wilke, L. K. Smith, and W. F. Krupke, “Auger upconversion losses in Nd-doped laser glasses,” Opt. Commun. 111, 263–268 (1994). [CrossRef]

]. Note that a factor of two has been added to both equations to account for the indistinguishability of Nd excited states. Our measurements were performed at low excitation such that ne <0.04, so Ne <<NgNt . Therefore, in this regime, migration (γB ) should give the main contribution to ETU. This hypothesis is corroborated by the linear behavior of γversus Nt observed for all studied glasses, shown in Fig. 2(a). From linear adjustments of data in Fig. 2(a), the following information were obtained:

• Q-98: γ=[(-0.2±0.3)x10-17+(3.49±0.05).Ntx10-37] cm3/s

• PGIZCa: γ=[(0.8±0.5)x10-17+ (2.8±0.1).Ntx10-37] cm3/s

• ZBLAN: γ=[(0.8±0.5) x10-17+ (2.1±0.2).Ntx10-37] cm3/s

These γ values can also be calculated from the excited-state absorption spectra. Using the data from Doualan et. al. [2

2. J. L. Doualan, C. Maunier, D. Descamps, J. Landais, and R. Moncorgé, “Excited-state absorption and up-conversion losses in the Nd-doped glasses for high-power lasers,” Phys. Rev. B 62, 4459–4463 (2000); (and references therein). [CrossRef]

] for phosphate glass LHG-8, γ=3.2Ntx10-37 cm3/s was evaluated for low excitation regime (ne<<1). Note that ref. [2

2. J. L. Doualan, C. Maunier, D. Descamps, J. Landais, and R. Moncorgé, “Excited-state absorption and up-conversion losses in the Nd-doped glasses for high-power lasers,” Phys. Rev. B 62, 4459–4463 (2000); (and references therein). [CrossRef]

] presents a general theoretical expression for γ, i.e., for low and high excitation densities. This γ value of the LHG-8 glass is very similar to our experimental result for Q-98, (3.49±0.05). Ntx10-37 cm3/s.

Fig. 2. (a) Upconversion parameter (γ) and (b) inversion density (γτ)-1 for Phosphate (Q-98), Fluoroindate (PGIZCa), and Fluorozirconate (ZBLAN) glasses as a function of the Nd3+ concentration (Nt). The values for only one concentration are showed for YLF. The lines in (a) are linear fitting, and in (b) are only guides for eyes.

For the modeling of Nd:glass lasers it is interesting to define a critical inversion density Nec=(γ.τ)-1, i.e., the Ne value where Wup=τ-1 =Wt/2. Fig. 2(b) shows that (γ.τ)-1 is not concentration independent as previously suggested for high power regime [1

1. S. A. Payne, G. D. Wilke, L. K. Smith, and W. F. Krupke, “Auger upconversion losses in Nd-doped laser glasses,” Opt. Commun. 111, 263–268 (1994). [CrossRef]

], but it decreases with Nt for all studied glasses. It should be noticed that for Fig. 2(b) data Nt increases by a factor 6–10 whereas τ decreases by ~2, indicating that (γ.τ)-1 is proportional to (Ntτ)-1 (B model) and it should really diminish. However, for high intensity this behavior could be different, since γ will be proportional to Ng and Ne.

It is very important to note that due to high sensitivity of the TL technique, the power levels used for γ determination are very low, corresponding to low inversion regime, ne<0.1. It should also be noticed that in this regime static (FD) processes are negligible while in the high excitation regime both FD and B mechanisms are relevant.

4. Conclusions

In summary, we have demonstrated that the nonlinear dependence of the TL signal with excitation power can be used to study the energy-transfer upconversion in Nd-doped materials. As a photothermal technique, this method does not require any knowledge on fluorescence kinetics, which is usually a complex phenomenon. The samples with high Nd3+ concentration present a considerable reduction in η with the increasing excitation power due to the efficient ETU processes. Migration-assisted energy transfer (Burstein) is the main mechanism responsible for the upconversion losses in our measurements. Besides, it was verified that the critical inversion density (γ.τ)-1 decreases with increasing Nd content. The approach based on TL technique appears as a good alternative for γ determination because of the high sensitivity of the method. Consequently, the measurements can be performed in a pump power regime that avoids damages in the investigated materials. Another advantage is the use of a cw pump source instead of a pulsed one. This reduces uncertainties in the pump intensity (related to beam power and waist) increasing the experiment accuracy.

Acknowledgments

We are thankful to CNPq and FAPESP for the financial support of this work. The authors thank to A. S. S. de Camargo, M. J. V. Bell, and D. N. Messias for careful reading of the manuscript.

References and links

1.

S. A. Payne, G. D. Wilke, L. K. Smith, and W. F. Krupke, “Auger upconversion losses in Nd-doped laser glasses,” Opt. Commun. 111, 263–268 (1994). [CrossRef]

2.

J. L. Doualan, C. Maunier, D. Descamps, J. Landais, and R. Moncorgé, “Excited-state absorption and up-conversion losses in the Nd-doped glasses for high-power lasers,” Phys. Rev. B 62, 4459–4463 (2000); (and references therein). [CrossRef]

3.

V. Pilla, T. Catunda, H. P. Jenssen, and A. Cassanho, “Fluorescence quantum efficiency measurements in the presence of Auger upconversion by the thermal lens method,” Opt. Lett. 28, 239–241 (2003). [CrossRef] [PubMed]

4.

M. Pollnau, P. J. Hardman, M. A. Kern, W. A. Clarkson, and D. C. Hanna, “Upconversion-induced heat generation and thermal lensing in Nd:YLF and Nd:YAG,” Phys. Rev. B 58, 16076–16092 (1998). [CrossRef]

5.

S. A. Payne, L. K. Smith, R. J. Beach, B. H. T. Chai, J. H. Tassano, L. D. DeLoach, W. L. Kway, R. W. Solarz, and W. F. Krupke, “Properties of Cr:LiSrAlF6 crystals for laser operation,” Appl. Opt. 33, 5526–5536 (1994.) [CrossRef] [PubMed]

6.

S. Guy, C. L. Bonner, D. P. Shepherd, D.C. Hanna, A. C. Tropper, and B. Ferrand, “High-inversion densities in Nd:YAG: Upconversion and Bleaching,” IEEE J. Quantum Electron. 34, 900–909 (1998). [CrossRef]

7.

Y. Guyot, H. Manaa, J. Y. Rivoire, R. Moncorgé, N. Garnier, E. Descroix, M. Bon, and P. Laporte, “Excited-state-absorption and upconversion studies of Nd3+-doped single crystals Y3Al5O12, YLiF4, and LaMgAl11O19,” Phys. Rev. B 51, 784–798 (1995). [CrossRef]

8.

P. J. Hardman, W. A. Clarkson, G. J. Friel, M. Pollnau, and D. C. Hanna, “Energy-transfer upconversion and thermal lensing in high-power end-pumped Nd:YLF laser crystals,” IEEE J. Quantum Electron. 35, 647–655 (1999). [CrossRef]

9.

J. L. Blows, T. Omatsu, J. Dawes, H. Pask, and M. Tateda, “Heat generation in Nd:YVO4 with and without laser action,” IEEE Phot. Technol. Lett. 10, 1727–179 (1998). [CrossRef]

10.

M. Pollnau, D. R. Gamelin, S. R. Lüthi, H. U. Güdel, and M. P. Hehlen, “Power dependence of upconversion luminescence in lanthanide and transition-metal-ion systems,” Phys. Rev. B 61, 3337–3346 (2000). [CrossRef]

11.

D. C. Brown, “Heat, fluorescence, and stimulated-emission power densities and fractions in Nd:YAG,” IEEE J. Quantum Electron. 34, 560–572 (1998). [CrossRef]

12.

S. M. Lima, A. A. Andrade, R. Lebullenger, A. C. Hernandes, T. Catunda, and M. L. Baesso, “Multiwavelength thermal lens determination of fluorescence quantum efficiency of solids: Application to Nd3+-doped fluoride glass,” Appl. Phys. Lett. 78(21), 3220–3222 (2001). [CrossRef]

13.

S. M. Lima, J. A. Sampaio, T. Catunda, A. C. Bento, C. M. Miranda, and M. L. Baesso, “Mode-mismatched thermal lens spectrometry for thermo-optical properties measurement in optical glasses: a review,” J. Non-Cryst. Solids 273, 215–227 (2000). [CrossRef]

14.

M. L. Baesso, A. C. Bento, A. A. Andrade, J. A. Sampaio, E. Pecoraro, L. A. O. Nunes, T. Catunda, and S. Gama, “Absolute thermal lens method to determine fluorescence quantum efficiency and concentration quenching of solids,” Phys. Rev. B. 57, 10545–10549 (1998). [CrossRef]

15.

C. Jacinto, S. L. Oliveira, L. A. O. Nunes, J. D. Myers, M. J. Myers, and T. Catunda, “Normalized lifetimes thermal lens method for determination of luminescence quantum efficiency and thermo-optical coefficients: Application to Nd3+-doped glasses,” (submitted).

16.

M. L. Baesso, J. Shen, and R. D. Snook, “Mode-mismatched thermal lens determination of temperature coefficient of optical path length in soda lime glass at different wavelengths,” J. Appl. Phys. 75(8), 3732–3737 (1994). [CrossRef]

OCIS Codes
(140.6810) Lasers and laser optics : Thermal effects
(160.3380) Materials : Laser materials
(160.4760) Materials : Optical properties
(190.7220) Nonlinear optics : Upconversion

ToC Category:
Research Papers

History
Original Manuscript: January 20, 2005
Revised Manuscript: March 4, 2005
Published: March 21, 2005

Citation
Carlos Jacinto, Samuel Oliveira, Tomaz Catundab, Acácio Andrade, John Myers, and Michael Myers, "Upconversion effect on fluorescence quantum efficiency and heat generation in Nd3+-doped materials," Opt. Express 13, 2040-2046 (2005)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-13-6-2040


Sort:  Journal  |  Reset  

References

  1. S. A. Payne, G. D. Wilke, L. K. Smith, W. F. Krupke, �??Auger upconversion losses in Nd-doped laser glasses,�?? Opt. Commun. 111, 263-268 (1994). [CrossRef]
  2. J. L. Doualan, C. Maunier, D. Descamps, J. Landais, and R. Moncorgé, �??Excited-state absorption and upconversion losses in the Nd-doped glasses for high-power lasers,�?? Phys. Rev. B 62, 4459-4463 (2000); (and references therein). [CrossRef]
  3. V. Pilla, T. Catunda, H. P. Jenssen, A. Cassanho, �??Fluorescence quantum efficiency measurements in the presence of Auger upconversion by the thermal lens method,�?? Opt. Lett. 28, 239-241 (2003). [CrossRef] [PubMed]
  4. M. Pollnau, P. J. Hardman, M. A. Kern, W. A. Clarkson, and D. C. Hanna, �??Upconversion-induced heat generation and thermal lensing in Nd:YLF and Nd:YAG,�?? Phys. Rev. B 58, 16076-16092 (1998). [CrossRef]
  5. S. A. Payne, L. K. Smith, R. J. Beach, B. H. T. Chai, J. H. Tassano, L. D. DeLoach, W. L. Kway, R. W. Solarz, and W. F. Krupke, �??Properties of Cr:LiSrAlF6 crystals for laser operation,�?? Appl. Opt. 33, 5526-5536 (1994.) [CrossRef] [PubMed]
  6. S. Guy, C. L. Bonner, D. P. Shepherd, D.C. Hanna, A. C. Tropper, and B. Ferrand, �??High-inversion densities in Nd:YAG: Upconversion and Bleaching,�?? IEEE J. Quantum Electron. 34, 900-909 (1998). [CrossRef]
  7. Y. Guyot, H. Manaa, J. Y. Rivoire, R. Moncorgé, N. Garnier, E. Descroix, M. Bon, and P. Laporte, �??Excited-state-absorption and upconversion studies of Nd3+-doped single crystals Y3Al5O12, YLiF4, and LaMgAl11O19,�?? Phys. Rev. B 51, 784-798 (1995). [CrossRef]
  8. P. J. Hardman, W. A. Clarkson, G. J. Friel, M. Pollnau, and D. C. Hanna, �??Energy-transfer upconversion and thermal lensing in high-power end-pumped Nd:YLF laser crystals,�?? IEEE J. Quantum Electron. 35, 647-655 (1999). [CrossRef]
  9. J. L. Blows, T. Omatsu, J. Dawes, H. Pask, and M. Tateda, �??Heat generation in Nd:YVO4 with and without laser action,�?? IEEE Phot. Technol. Lett. 10, 1727-179 (1998). [CrossRef]
  10. M. Pollnau, D. R. Gamelin, S. R. Lüthi, H. U. Güdel, and M. P. Hehlen, �??Power dependence of upconversion luminescence in lanthanide and transition-metal-ion systems,�?? Phys. Rev. B 61, 3337-3346 (2000). [CrossRef]
  11. D. C. Brown, �??Heat, fluorescence, and stimulated-emission power densities and fractions in Nd:YAG,�?? IEEE J. Quantum Electron. 34, 560-572 (1998). [CrossRef]
  12. S. M. Lima, A. A. Andrade, R. Lebullenger, A. C. Hernandes, T. Catunda, M. L. Baesso, �??Multiwavelength thermal lens determination of fluorescence quantum efficiency of solids: Application to Nd3+-doped fluoride glass,�?? Appl. Phys. Lett. 78(21), 3220-3222 (2001). [CrossRef]
  13. S. M. Lima, J. A. Sampaio, T. Catunda, A. C. Bento, C. M. Miranda, and M. L. Baesso, �??Mode-mismatched thermal lens spectrometry for thermo-optical properties measurement in optical glasses: a review,�?? J. Non-Cryst. Solids 273, 215-227 (2000). [CrossRef]
  14. M. L. Baesso, A. C. Bento, A. A. Andrade, J. A. Sampaio, , E. Pecoraro, L. A. O. Nunes, T. Catunda, and S. Gama, �??Absolute thermal lens method to determine fluorescence quantum efficiency and concentration quenching of solids,�?? Phys. Rev. B. 57, 10545-10549 (1998). [CrossRef]
  15. C. Jacinto, S. L. Oliveira, L. A. O. Nunes, J. D. Myers, M. J. Myers, and T. Catunda, �??Normalized lifetimes thermal lens method for determination of luminescence quantum efficiency and thermo-optical coefficients: Application to Nd3+-doped glasses,�?? (submitted).
  16. M. L. Baesso, J. Shen, and R. D. Snook, �??Mode-mismatched thermal lens determination of temperature coefficient of optical path length in soda lime glass at different wavelengths,�?? J. Appl. Phys. 75(8), 3732-3737 (1994). [CrossRef]

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

Figures

Fig. 1. Fig. 2.
 

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited