Transient and persistent spectral hole burning in
3+
Eu -doped sol-gel produced SiO2 glass
Transient and Persistent Holes
D. M. Boye1, T. S. Valdes1, J. H. Nolen1 , A.J. Silversmith2,
K.S. Brewer2, R. E. Anderman2 and R. S. Meltzer3
Type of hole burning depends strongly on
the final annealing temperature and
weakly on the organosilicate precursor.
1Davidson
College, Davidson, NC 28036 USA
2 Hamilton College, Clinton, NY 13323 USA
3University of Georgia, Athens, GA 30602 USA
Abstract
Tann
Transient and persistent spectral hole burning (TSHB and PSHB) experiments were performed on
Eu3+ ions in sol-gel SiO2 glasses with aluminum co-doping. Differences in the hole burning
behavior were observed among samples made from two organosilicate precursors that were
annealed to a series of final temperatures. All glasses exhibited persistent spectral holes when
annealed to 800C but, as the annealing temperature was raised to 1000C, an increasing number of
Eu3+ ions exhibited TSHB with a corresponding decrease in the number showing PSHB behavior.
This is consistent with a reduction in metastable configurations with an increased final annealing
temperature. The TSHB behavior is similar to that observed for Eu3+-doped silicate melt glass.
TEOS
Transient and Persistent Hole Profiles
T = 1.65K
=578nm
TMOS
800°C
PSHB only
P and T SHB
900°C
P and T SHB
P and T SHB
75MHz
1000°C
P and T SHB
TSHB only
290MHz
•There is less likelihood of photo-induced
rearrangement.
Fluorescence (arb. units)
TEM Images for TEOS and TMOS sol-gel precursors
All samples annealed to 900°C
TEOS
7F 5D
0
0
900 TEOS
Fluorescence
•As Tann is raised, the glass becomes denser.
Eu Local Environment
80MHz
excitation
540MHz
5% Al 1000C
Persistent Holes
565
570
575
580
585
-2
590
-1
0
1
2
Frequency [GHz]
TMOS
Transient Hole Width [MHz] Antihole position [MHz]
Transient Hole Behavior
Silicon
Oxygen
Al - network modifier
Europium
The average pore size in the TMOS samples is
smaller and there is a narrower range of sizes than in
the TEOS samples.
•Antihole position and hole width
vary systematically across the
7F 5D excitation line due to a
0
0
linear variation in A02 .
Persistent Hole Behavior
0
3500
Persistent Hole Profiles
800TEOS 1.5K Feofilov
800TEOS 2.2K
900TEOS 1.6K
900TMOS 1.4K
Persistent Hole Width [MHz]
3000
10 sec
30 sec
2 min
Fluorescence
800 TMOS
Transient Holes
5 min
10 min
2500
2000
•Transient hole width in sol-gel
glasses shows weaker dependence
on ex than the melt glass,
indicating weaker crystal field
coupling. This may be because the
sol-gel glasses are not fully
densified.
1500
1000
500
0
570
572
574
576
578
580
200
175
150
125
100
75
160
140
120
100
80
60
900 TEOS 1.6K
40
900 TMOS 1.4 K
20
1000 TMOS 2K
Schmidt et al
0
571
582
573
575
577
579
581
Excitation Wavelength [nm]
T=1.7K
=578nm
800 TEOS
-2
-1
0
1
2
3
4
Constant fluence experiments show PSHB is 1-photon process.
5
Proposed mechanisms for PSHB:
35
1
 Photo-induced rearrangement of local environment
Frequency [GHz]
a) Fluorescence level decreases
in time as the hole is
burned. The long tail is fit to
an exponential with a time
constant of 2.5s-1.
a
0.75
x Photoionization of Eu3+
0.62e-2.5t
Fluorescence
x Photo-reduction of Eu3+ to Eu2+
Experiment
Ingredients:
Er(NO3)3•6H2O
Al(NO3)3•9H2O
H2O (deionized)
C3H6O
HNO3
Tetraethylorthosilicate (TEOS)
Titanium n-butoxide (TBOT)
Hole recovery time dependence
0.5
b) The fast component has a
time constant 10x faster.
b
0.38e-24t
0.25
% Hole Depth
-3
Hole burning time dependence
30
% Hole Depth
-4
25
20
35
30
25
20
15
10
5
0
0
15
200
400
600
800
1000
Delay Time [ms]
10
5
Reaction
- Hydrolysis and
condensation
- Room temp.
- pH 1.5 to 3.5
Gelation
- Polymeric gel forms
- Supports stress
elastically
-”Wet” gel
- 2 days, 40°C
Aging
- Solvent escapes
- Pore contraction
- Shrinkage
- 2 days, 60°C
Drying
- Shrinkage
- Cracking
- Densification
- Pore collapse
- 2 days, 90°C
0
0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0
2
Time [s]
4
6
8
10
Delay Time [s]
Both hole burning and recovery rates indicate:
• Fast component – affects 1/3 of ions in first 100ms.
• Slow component - ~10 times slower than fast component.
Experimental Setup
Annealing Process
Conclusions
1000
Temperature (oC)
-5
Excitation Wavelength [nm]
• Transient hole burning observed on Eu 3+ sol-gel produced glass for first time.
800
Argon
Laser
600
Dye Laser
Cryostat with
sample @ 77K
• TSHB mechanism: redistribution of electron population among hyperfine levels.
400
• Combination of PSHB and TSHB observed with the proportion of the two being strongly
dependent on the final annealing temperature.
Waveform
Synthesizer
200
0
0
2
4
6
8
10
Ammeter
time (days)
PMT
Computer with
Labview software
Oscilloscope
Monochromator
• PSHB mechanism: photo-induced rearrangement of local environment. Regions at or near
a pore boundary are ripe for metastable configurations having a range of barrier energies.
References
S.P. Feofilov, K.S. Hong, R.S. Meltzer, W. Jia and H. Liu, Phys. Rev. B60, 9406 (1999).
Corresponding author:
Dr. Dan Boye
Physics Department
Davidson College
P.O. Box 7133
Davidson, NC 28035-7133
daboye@davidson.edu
T.T.Schmidt, R.M. Macfarlane, and S. Volker, Phys. Rev. B50, 15707 (1994).
Acknowledgements
AJS and DMB thank the NSF for a Research Opportunity Award associated with NSF DMR 9871864.
Thanks to H.Y. Fang, currently of Sandia National Laboratories, for performing the TEM and x-ray diffraction work.
12
Transient and persistent spectral hole burning in
3+
Eu -doped sol-gel produced SiO2 glass
Transient and Persistent Holes
D. M. Boye1, T. S. Valdes1, J. H. Nolen1 , A.J. Silversmith2,
K.S. Brewer2, R. E. Anderman2 and R. S. Meltzer3
Type of hole burning depends strongly on
the final annealing temperature and
weakly on the organosilicate precursor.
1Davidson
College, Davidson, NC 28036 USA
2 Hamilton College, Clinton, NY 13323 USA
3University of Georgia, Athens, GA 30602 USA
Abstract
Tann
Transient and persistent spectral hole burning (TSHB and PSHB) experiments were performed on
Eu3+ ions in sol-gel SiO2 glasses with aluminum co-doping. Differences in the hole burning
behavior were observed among samples made from two organosilicate precursors that were
annealed to a series of final temperatures. All glasses exhibited persistent spectral holes when
annealed to 800C but, as the annealing temperature was raised to 1000C, an increasing number of
Eu3+ ions exhibited TSHB with a corresponding decrease in the number showing PSHB behavior.
This is consistent with a reduction in metastable configurations with an increased final annealing
temperature. The TSHB behavior is similar to that observed for Eu3+-doped silicate melt glass.
TEOS
Transient and Persistent Hole Profiles
T = 1.65K
=578nm
TMOS
800°C
PSHB only
P and T SHB
900°C
P and T SHB
P and T SHB
75MHz
1000°C
P and T SHB
TSHB only
290MHz
•There is less likelihood of photo-induced
rearrangement.
Fluorescence (arb. units)
TEM Images for TEOS and TMOS sol-gel precursors
All samples annealed to 900°C
TEOS
7F
0
5D
0
900 TEOS
Fluorescence
•As Tann is raised, the glass becomes
denser.
Eu Local Environment
80MHz
excitation
540MHz
5% Al 1000C
Persistent Holes
565
570
575
580
585
-2
590
-1
0
1
2
Frequency [GHz]
TMOS
Transient Hole Width [MHz] Antihole position [MHz]
Transient Hole Behavior
Silicon
Oxygen
Al - network modifier
Europium
The average pore size in the TMOS samples is
smaller and there is a narrower range of sizes than in
the TEOS samples.
•Antihole position and hole width
vary systematically across the
Persistent Hole Behavior
0
7F
3500
Persistent Hole Profiles
Persistent Hole Width [MHz]
10 sec
30 sec
2 min
5 min
10 min
2500
0
5D
0
excitation line due to a
linear variation in A 02 .
800TEOS 1.5K Feofilov
800TEOS 2.2K
900TEOS 1.6K
900TMOS 1.4K
3000
Fluorescence
800 TMOS
Transient Holes
2000
•Transient hole width in sol-gel
glasses shows weaker dependence
1500
on  ex than the melt glass,
indicating weaker crystal field
coupling. This may be because the
sol-gel glasses are not fully
densified.
1000
500
0
570
572
574
576
578
580
200
175
150
125
100
160
75
140
120
100
80
60
900 TEOS 1.6K
40
900 TMOS 1.4 K
20
1000 TMOS 2K
Schmidt et al
0
571
582
573
575
577
579
581
Excitation Wavelength [nm]
T=1.7K
=578nm
800 TEOS
-2
-1
0
1
2
3
4
Constant fluence experiments show PSHB is 1-photon process.
5
Proposed mechanisms for PSHB:
35
1
 Photo-induced rearrangement of local environment
Frequency [GHz]
a) Fluorescence level decreases
in time as the hole is
burned. The long tail is fit to
an exponential with a time
constant of 2.5s-1.
a
0.75
x Photoionization of Eu3+
0.62e-2.5t
Fluorescence
x Photo-reduction of Eu3+ to Eu2+
Experiment
Ingredients:
Er(NO3)3•6H2O
Al(NO3)3•9H2O
H2O (deionized)
C3H6O
HNO3
Tetraethylorthosilicate (TEOS)
Titanium n-butoxide (TBOT)
Hole recovery time dependence
0.5
b) The fast component has a
time constant 10x faster.
b
0.38e-24t
0.25
% Hole Depth
-3
Hole burning time dependence
30
% Hole Depth
-4
25
20
35
30
25
20
15
10
5
0
0
15
200
400
600
800
1000
Delay Time [ms]
10
5
Reaction
- Hydrolysis and
condensation
- Room temp.
- pH 1.5 to 3.5
Gelation
- Polymeric gel forms
- Supports stress
elastically
-”Wet” gel
- 2 days, 40°C
Aging
- Solvent escapes
- Pore contraction
- Shrinkage
- 2 days, 60°C
Drying
- Shrinkage
- Cracking
- Densification
- Pore collapse
- 2 days, 90°C
0
0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0
2
Time [s]
4
6
8
10
Delay Time [s]
Both hole burning and recovery rates indicate:
• Fast component – affects 1/3 of ions in first 100ms.
• Slow component - ~10 times slower than fast component.
Experimental Setup
Annealing Process
Conclusions
1000
Temperature (oC)
-5
Excitation Wavelength [nm]
• Transient hole burning observed on Eu 3+ sol-gel produced glass for first time.
800
Argon
Laser
600
Dye Laser
Cryostat with
sample @ 77K
• TSHB mechanism: redistribution of electron population among hyperfine levels.
400
• Combination of PSHB and TSHB observed with the proportion of the two being strongly
dependent on the final annealing temperature.
Waveform
Synthesizer
200
0
0
2
4
6
8
10
Ammeter
time (days)
PMT
Computer with
Labview software
Oscilloscope
Monochromator
• PSHB mechanism: photo-induced rearrangement of local environment. Regions at or near
a pore boundary are ripe for metastable configurations having a range of barrier energies.
References
S.P. Feofilov, K.S. Hong, R.S. Meltzer, W. Jia and H. Liu, Phys. Rev. B60, 9406 (1999).
Corresponding author:
Dr. Dan Boye
Physics Department
Davidson College
P.O. Box 7133
Davidson, NC 28035-7133
daboye@davidson.edu
T.T.Schmidt, R.M. Macfarlane, and S. Volker, Phys. Rev. B50, 15707 (1994).
Acknowledgements
AJS and DMB thank the NSF for a Research Opportunity Award associated with NSF DMR 9871864.
Thanks to H.Y. Fang, currently of Sandia National Laboratories, for performing the TEM and x-ray diffraction work.
12