fluoride glasses – materials for bulk lasers and fibre optical amlifiers
Post on 19-Mar-2016
38 Views
Preview:
DESCRIPTION
TRANSCRIPT
FLUORIDE GLASSES – MATERIALS FOR BULK LASERS AND
FIBRE OPTICAL AMLIFIERS
Michał Żelechower, Silesian University of Technology, Katowice, Poland
1. What are fluoride glasses?
2. The role of rare earth elelments
3. Interaction of electromagnetic radiation with mattera. Scattering, absorption, spontaneous and stimulated emission
b. Reconstruction of electron energy structure
c. Radiative and non-radiative transitions
4. Real structure of fluoride glasses
5. Applications – advantages and disadvantages (drawbacks)
What is it?
Fluoride glasses can be formed by total replacement of oxygen atoms in oxide glasses
by fluorine atoms
They are manufactured by melting of high purity single element fluorides mixture
HEISENBERG’S UNCERTAINTY PRINCIPLE
tE
E~2·10-19 eV t~1h
E~10 eV t~10-15s
FREE ATOM SOLID
ENER
GY
Energy diagram showing two
atoms encountering and resulting in a new
molecule
DIELECTRICS
VALENCE BAND
FORBIDDEN BAND(ENERGY GAP)
CONDUCTION BAND
ENER
GY
Eg > 2 eV
EMPTY
FULL
EF
DOPED DIELECTRICS
VALENCE BAND
CONDUCTION BAND (EMPTY)
DOPED IONS LEVELS USED IN LASER ACTION
FOR INSTANCE RARE EARTH ELEMENTS IN
GLASSES
http://www.gel.ulaval.ca/~copgel/conferences/edfa1/tsld001.htm
RARE EARTH IONS IN CRYSTALS AND GLASSES
RARE EARTH IONS IN CRYSTALS AND GLASSES
RARE EARTH IONS IN CRYSTALS AND GLASSES
RARE EARTH IONS IN CRYSTALS AND GLASSES
TABLE 1. CONVERSION FACTORS FOR ENERGY UNITS
Unit joule electron volt cm–1
joule 1 6.24 × 1018 5.034 × 1022
electron
volt1.602 × 10–19 1 8065.73
cm–1 1.9864 × 10–23 1.24 × 10–4 1
][cmE
10000600nmλ
eVE1240nmλ
1
[nm]λ10000600][cmE
nmλ1240eVE
1
EXAMPLE : CONVERSION OF ENERGY IN JOULES TO CM-1
Given: A HeNe laser photon has a wavelength of 632.8 nanometersFind: (a) Photon energy in joules
(b) Photon energy in cm–1
Solution:
(a) find energy of HeNe laser photon in joules.
Where h=6.625´ 10-34J · secc=3´ 108m/sec =632.8nm=632.8´ 10-9m
(b) Use Table 1 to convert 3.14´ 10-19 joules to cm-1. Locate "joule" in the first row in the left hand column. Follow this row over to the column headed "cm-1." At the intersection of the row and column, find the conversion factor 5.034´ 1022 cm-1/joule. Multiply this factor by 3.14´ 10-19 joules to change the energy from joules to cm-1.
The "joule" units cancel, and you get E=15,806.8cm-1
THE INTERACTION OF RADIATION WITH MATTER
Small no. of states-almost transparent
Large no. of states -strongly absorbed
Energy
X-rays
Ultraviolet
Visible
Infrared
Microwaves
Ionisation energy
Rotation
Vibration
Electronic level changes
Phototionisation
Scattering
ATOM MUST RETURN FROM EXCITED STATE TO GROUND STATE.
HOW?
SEVERAL WAYS TO RETURN TO GROUND STATE
QUANTUM YIELD OF LUMINESCENCE
SEVERAL WAYS TO RETURN TO GROUND STATE.
LIFETIMES
FLUORESCENCE VERSUS PHOSPHORESCENCE
Spin multiplicity
A state can be specified by its spin multiplicity (2S+1).
No. unpaired electrons S Multiplicity State
0 S = 0 2S + 1 = 1 singlet1 S = 1/2 2S + 1 = 2 doublet2 S = 1 2S + 1 = 3 triplet3 S = 3/2 2S + 1 = 4 quartet
S0 ground state singletS1, S2……excited state singletsT1, T2….…excited state triplets
SYMBOLS USED IN ATOMIC PHYSICS
Pr
Eu
Ho
Er
Tm
Wavelength [nm]
Wavenumber [cm-1]A
bsor
banc
e
3H6
3F2
3F3
3F4
1G4
7F6
5D0
5D1
5D2
5D3
5L6
5I75I6
5F5
5S2 , 5F4
5F2
5F33K8
5G6
5G5
5G4
3K7
30000 20000
1D2
3P0
3P1,1I6
3P2
4I13/24I11/24I9/2
4F9/2
4S3/2
2H11/2
4F7/2
4F5/2
4F3/22G9/2
4G11/2
4G9/2
2K15/2
300 400 500 600 700 800
3F4
3H5
3H4
3F2 , 3F3
1G4
1D2
1000 2000
10000 5000
REE ABSORPTION SPECTRA IN FLUORIDE GLASSES
EACH ABSORPTION LINE CORRESPONDS TO THE RESPECTIVE ELECTRON TRANSITION BETWEEN
TWO ENERGY LEVELS (GROUND STATE AND EXCITED STATE)
WE ARE ABLE TO RECONSTRUCT THE ELECTRON ENERGY STRUCTURE ON THE BASE OF
ABSORPTION SPECTRA
Pr Eu Ho Er Tm
RECONSTRUCTED ELECTRON ENERGY LEVELS IN FLUOROINDATE GLASSES
Ener
gy [c
m-1]
0
5000
10000
15000
20000
25000
30000
4I15/23H4
1D2
1G4
3F23F3
3H4
3H5
3F4
3H6
2K15/24G9/24G11/2
2G9/2
4F3/24F5/2
4F7/22H11/24S3/2
4F9/2
4I9/2
4I11/2
4I13/2
3K7
5G4
5G5
5G63K85F25F3
5S25F4
5F5
5I5
5I6
5I7
5I8
5D45G45G25L65D3
5D2
5D1
5D0
3F0
3F63H6
3F2
3F3
3F4
1G4
1D2
3P0
3P1
1I6
3P2
SPONTANEOUS EMISSION
E3
E2
E1
Pij = Pji
P23 > P13 >> P12
INVERSION
N2 >> N1
2 >> 3
THREE-LEVEL LASER (TRANSITION PROBABILITIES AND LIFETIMES)
STIMULATED EMISSION
Stimulated EmissionStimulated emission is the exact analogue of absorption. An excited species interacts with the oscillating electric field and gives up its energy to the incident radiation.
Emission of Radiation
Stimulated emission is an essential part of laser action.
U
L
h
L
hU
2h
LIFETIMES OF EXCITED STATES
FOUR-LEVEL LASER (Cr3+ doped ruby)
E3
E2
E1
E = h· = E2 – E1
THREE-LEVEL LASER (quantum amplifier)
OPTICAL PUMPING
10-8 s
10-3 s
Time-schedule of laser action
To amplify number of photons going through the atoms we need more atoms in upper energy level than in lower.
Amplification or loss is just Nupper-Nlower.
Nupper > Nlower, more out than in
Nupper < Nlower, fewer out than in
PRINCIPLE OF LASER ACTION
PRINCIPLE OF LASER ACTIONNUMBER OF PHOTONS ~ 2N (N – ACTIVE ELEMENT CONTENT)
LASER RESONANCE SYSTEM
First commercial fluoride glass – about 1990
FLUOROZIRCONATE GLASS
ZrF4-BaF2-LaF3-AlF3-NaF
Acronym - ZBLANFLUOROINDATE GLASS
InF3-ZnF2-BaF2-SrF2-GaF3-NaF
Acronym - IZBSGN
1974 - Marcel & Michel Poulain and Jacques Lucas discovered first fluoride glass
(Univ. Rennes, France)
HISTORY
Accidentally !!!
ADVANTAGES
1. Low phonon energy
2. Low absorption in IR range
3. Wide transmission band
4. High refraction index
Comparison of various glasses properties to those of silica glasses
A PIECE OF PHYSICS
Phonons in a lattice Acoustic branch-wide frequency band
Optical branch - almost constant frequency
THIS FREQUENCY IS MUCH LOWER IN FLUORIDE GLASSES THAN IN SILICA GLASSES
IR light absorbtion in fluoride glasses is much lower than in silica glasses
VIBRATIONS OF DIATOMIC CHAIN – OPTICAL PHONONS
Equation of motion (Newton’s second principle)
Disperssion relations
0 3000 6000 9000 12000 15000
DŁUGOŚĆ FALI [nm]Wavelength
TRANSMISSION BAND
FLUOROZIRCONATE GLASSES
SILICAGLASSES
FLUOROINDATE GLASSES
Wavelength [m]
Wavenumber [cm-1]
Tran
smis
sion
[%]
TRANSMISSION BAND – FLUOROINDATE GLASS
0
100
4000 3000 2000 1000
6 12 18243
800 600 400
14
12 16 20 24
Pr Eu Ho Er Tm
ELECTRON ENERGY LEVELS
Ener
gy [c
m-1]
0
5000
10000
15000
20000
25000
30000
4I15/23H4
1D2
1G4
3F23F3
3H4
3H5
3F4
3H6
2K15/24G9/24G11/2
2G9/2
4F3/24F5/2
4F7/22H11/24S3/2
4F9/2
4I9/2
4I11/2
4I13/2
3K7
5G4
5G5
5G63K85F25F3
5S25F4
5F5
5I5
5I6
5I7
5I8
5D45G45G25L65D3
5D2
5D1
5D0
3F0
3F63H6
3F2
3F3
3F4
1G4
1D2
3P0
3P1
1I6
3P2
Wavenumber [cm-1]
Wavelength [nm]
Lum
ines
cenc
e in
tens
ity [a
.u.]
LUMINESCENCE (IZBSGN) Ho
9000 10000 11000 12000 13000 14000 15000
5F5-5I8
5S2-5I7
5I4-5I8
5I5-5I8
5F5-5I75S2-
5I6
5I6-5I8
1200 1100 1000 900 800 700
0.5 % mol.
6 % mol.
0.5 % mol.
E [cm-1]E [cm-1]
6 % mol.
EMISSION
E [cm-1] 0.5 % mol
EMISSION (IZBSGN)
Ho
Wavenumber [cm-1]
Wavelength [nm]
Lum
ines
cenc
e in
tens
ity [a
.u.]
LUMINESCENCE (IZBSGN) Pr
14000 15000 16000 17000 18000 19000
3P1 |3F3
3P0 |3F2
3P1 |3F4
1D2 |3H5
3P0 |3H6
3P1 |3H6
1D2 |3H4
3P0 |3H5
3P1 |3H5
720 680 640 600 560 520
EMISSION
E [cm-1]
EMISSION (IZBSGN)
Pr
Wavenumber [cm-1]
Wavelength [nm]
Lum
ines
cenc
e in
tens
ity [a
.u.]
LUMINESCENCE (IZBSGN) Er
14400 15000 15600
4S3/2-4I15/2
4S3/2-4I13/2
4F9/2-4I15/2
11600 12000
4I11/2-4I15/2
9600 10000 10400
690 660 630
1050 1000 950
870 840
18000 18600 19200
560 540 520
EMISSION
E [cm-1]Er
EMISSION (IZBSGN)
Wavenumber [cm-1] Wavenumber [cm-1]
Lum
ines
cenc
e in
tens
ity [a
.u.]
Inte
nsyw
ność
lum
ines
cenc
ji [j.
wzg
l.]
LUMINESCENCE (IZBSGN)
Tm Tm + Tb
EMISSION
12000 14000 16000 18000 20000 22000 24000
wzb. = 470nm (1G4)
wzb. = 355nm (1D2)
0.5% Tm
0.5% Tm
1G4- 3F4
1G4- 3H5
wzb. = 470nm (1G4)
wzb. = 355nm (1D2)
1% Tm + 3% Tb
1% Tm + 3% Tb
(Tb)
(Tm)1G4-
3H5
(Tb)5D4-
7F5
5D4 |7F4
5D4 | 7F3
1G4- 3F4 (Tm)
1D2-3F2
1D2-3F3 1D2-
3H4
1D2-3H5
1D2-3F4
1D2-3F4 (Tm)
(Tb)5D4-
7F5
12000 14000 16000 18000 20000 22000
EMISSION (IZBSGN)
Tm E [cm-1]
E [cm-1]
EMISSION (IZBSGN)
Tm - Tb
useless
Czas życia [ms] Aktywator Poziom Stężenie [%mol] Zmierzony m Obliczony rad
Wydajność kwant.
=m/rad [%] 0.5 0.012 36.4 3P0 2 0.012
0.033 36.4
0.05 0.400 92.6
Pr 1D2
2 0.005
0.432
1.2 Eu 5D0 2 0.370 6.320 5.9
1 0.140 31.7 Ho 5S2 6 0.078
0.442 17.6
2 0.183 34.8 4S3/2 8 0.028
0.526 5.3
2 0.299 40.3 4F9/2 8 0.261
0.741 35.2
2 6.680 99.6
Er 4I11/2
8 3.550 6.710
52.9 0.1 0.048 66.7 0.5 0.048 66.7
1D2
5 0.005
0.072
6.9 0.1 0.634 77.8 0.5 0.313 38.4
1G4
5 0.004
0.815
0.5 0.1 1.287 99.0 0.5 1.000 76.9
3H4
5 0.020
1.300
1.5 0.1 4.400 55.0
Tm
3F4 5 0.700
8.000 8.8
Lifetime [ms] Dopant Level Concentr. [%mol] Experimental m Computed rad
Quantumefficiency
= m / rad [%] 0.5 0.012 36.4
LIFETIMES & QUANTUM YIELDS OF DOPED FLUOROINDATE GLASSES
DISADVANTAGES (DRAWBACKS)
1. Substrates are hygroscopic (built-in OH groups result in additional absorption band in IR range)
2. Difference of TX and Tg is low ( 100 0C)
3. Crystallization susceptibility is high
Tg – glass transformation temperatureTX – crystallization temperature (beginning)
TP - crystallization temperature (peak)
T = Tx – Tg
HRUBY PARAMETER
H = (TX – TG) / TG
SAAD PARAMETER :
S = [(TX – TG) (TP – TX)] / TG
PARAMETERS OF STABILITY
Szkło fluoroindowe domieszkowane Ln3+
Tg [0C] Tx [0C] Tp [0C] T [0C] H S
A
K
T
Y
W
A
T
O
R
1 % mol PrF3 (*)
2 % mol EuF3 (**)
2 % mol EuF3 (*)
8 % mol EuF3 (*)
0.5 % mol HoF3 (*)
6 % mol HoF3 (*)
2 % mol ErF3 (***)
8 % mol ErF3 (***)
0.5 % mol TmF3 (*)
5 % mol TmF3 (*)
294
294
294
307
294
306
305
310
294
300
408
402
406
389
410
386
423
375
409
388
434
426
431
398
430
399
457.5
382
430
394
114
108
112
82
116
80
118
65
115
88
0.39
0.37
0.38
0.27
0.39
0.26
0.39
0.21
0.39
0.29
10.08
8.82
9.52
2.40
7.89
3.40
13.35
1.47
8.21
1.76
(*) IZBSGN (**) IZBS (***) IZBSGL
Various dopants in fluoride glass
108 112
116
118
115
CHARACTERISTIC TEMPERATURES OF FLUORINDATE GLASSES
GLOVE DRY PREPARATION BOX
GLOVE DRY MELTING BOX
Pr3+ doped fluoroindate glass
REVERSE MONTE CARLO MODELLING (RMC)
RIETVELD MODELLING
STRUCTURE OF FLUORIDE GLASSES
VARIATION OF GIBBS FREE ENERGY DURING VITRIFICATION AND CRYSTALLIZATION
liquid
Overcooled liquid
glass
Single crystal
Stable glass
Range of structural order
STRUCTURE OF FLUOROZIRCONATE
GLASS (ZBLAN)
POULAIN & LUCAS
1974
PROJECTION OF THE RMC CUBIC BOX SHOWING THE 300 [MF6] POLYHEDRA NETWORK.
EXAMPLE OF RMC MODELLING (NaPbM2F9)
NaPbFe2F9
[MF6] octahedra are in blue; Na atoms in green and Pb atoms in red
Five [MF6] polyhedra linked by edges as found in the RMC model
NaPbM2F9
EXPERIMENTAL VERIFICATION BY NEUTRON DIFFRACTION OR
LOW ANGLE X-RAY SCATTERING
SiO2 - crystallineI coordination zone – 3 at
II coordination zone – 3 at
III coordination zone – 6 at
SiO2 - amorphousI coordination zone – 3 at
II coordination zone – 4 at
III coordination zone – 4 at
EXAMPLE
LEAST SQUARES FIT TO EXPERIMENTAL RESULTS (NEUTRON DIFFRACTION AND X-RAY
SCATTERING)
NaPbM2F9 : neutron data for M = Fe
neutron data for M = V
LEAST SQUARES FIT TO EXPERIMENTAL RESULTS (NEUTRON DIFFRACTION AND X-RAY
SCATTERING)NaPbM2F9 (M = Fe, V)
X-ray data for M = Fe
LEAST SQUARES FIT TO EXPERIMENTAL RESULTS (NEUTRON DIFFRACTION AND X-RAY
SCATTERING)NaPbM2F9 (M = Fe, V)
REFERENCEShttp://www.studsvik.uu.se/Software/RMC/mcgr.htmhttp://tigger.phy.bris.ac.uk/~liqwww/links.htmlhttp://www.cristal.org/glasses/glassvir.html
http://www.cis.tugraz.at/ptc/specmag/struct/s.htmhttp://www.materials.leeds.ac.uk/Groups/Photonics/photonic.htm
http://www.gel.ulaval.ca/~copgel/conferences/edfa1/sld001.htm
http://irfibers.rutgers.edu/ir_rev_intro.htmlhttp://www.mete.metu.edu.tr/PEOPLE/FACULTY/aydinol/gfa/sld001.htm
top related