Luminescence in the fluoride-containing phosphate-based glasses: A possible origin of their high resistance to nanosecond pulse laser-induced damage

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Abstract Fusion power offers the prospect of an almost inexhaustible source of energy for future generations. It was reported that fusion fuel gains exceeding unity on the National Ignition Facility (NIF) were achieved, but so far great deal of scientific and engineering challenges have to be overcome for realizing fusion power generation. There is a bottleneck for color-separation gratings in NIF and other similar inertial confinement fusion (ICF) lasers. Here we show a series of high performance phosphate-based glasses that can transmit the third harmonic frequency (3ω) laser light with high efficiency meanwhile filter the fundamental (1ω) and the second harmonic frequency (2ω) laser lights through direct absorption and especially they exhibit excellent damage threshold induced by nanosecond pulse laser compared with that of the fused silica used in NIF. Yellowish-orange fluorescence emits during the laser-material interaction process and it can be tailored through regulating the glass structure. Study on its structural origin suggests that the fluorescence emission is a key factor that conduces to the high laser-induced damage resistance of these glasses. The results also indicated the feasibility of utilizing these high performance glasses in novel color separation optics, allowing novel design for the final optics assembly in ICF lasers.

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### OPEN

SUBJECT AREAS:

STRUCTURE OF SOLIDS

AND LIQUIDS

OPTICAL MATERIALS AND

STRUCTURES

Received
7 October 2014

Accepted
27 January 2015

Published
26 February 2015

Correspondence and

requests for materials

should be addressed to

[B.P. (bpeng@opt.ac.](mailto:bpeng@opt.ac.cn)

[cn) or P.F.W.](mailto:bpeng@opt.ac.cn)

[(pfwang@opt.ac.cn)](mailto:pfwang@opt.ac.cn)

## Luminescence in the fluoride-containing phosphate-based glasses: A possible origin of their high resistance to nanosecond pulse laser-induced damage

Pengfei Wang 1, Min Lu 1, Fei Gao 1, Haitao Guo 1, Yantao Xu 1, Chaoqi Hou 1, Zhiwei Zhou 2 & Bo Peng 1,3

1State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of
Sciences, 710119, Xi’an, P. R. China, 2 Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing100084, P. R.
China, 3 Institute of Advanced Materials, Nanjing University of Posts & Telecommunications, Nanjing, 210023, P. R. China.

Fusion power offers the prospect of an almost inexhaustible source of energy for future generations. It was
reported that fusion fuel gains exceeding unity on the National Ignition Facility (NIF) were achieved, but so
far great deal of scientific and engineering challenges have to be overcome for realizing fusion power
generation. There is a bottleneck for color-separation gratings in NIF and other similar inertial confinement
fusion (ICF) lasers. Here we show a series of high performance phosphate-based glasses that can transmit the
third harmonic frequency (3v) laser light with high efficiency meanwhile filter the fundamental (1v) and
the second harmonic frequency (2v) laser lights through direct absorption, and especially they exhibit
excellent damage threshold induced by nanosecond pulse laser compared with that of the fused silica used in
NIF. Yellowish-orange fluorescence emits during the laser-material interaction process, and it can be
tailored through regulating the glass structure. Study on its structural origin suggests that the fluorescence
emission is a key factor that conduces to the high laser-induced damage resistance of these glasses. The
results also indicated the feasibility of utilizing these high performance glasses in novel color separation
optics, allowing novel design for the final optics assembly in ICF lasers.

he attraction of perspective inexhaustible clean energy source from nuclear fusion has stimulated worldwide
intensive research on giant lasers similar to the NIF for many years. The US NIF is thought to be the first step
on the way to achieve potential unlimited fusion energy through laser-driven controlled inertial confine# T
ment fusion 1,2 . A most promising fusion shot on the NIF took place on last September 3, followed by a latest report
on achievement of fusion fuel gains exceeding unity on the NIF 4 . But the existing unexpected technical problems
still forced the ICF researchers to accept that the ignition is still a long way off to carry the far-off promise of clean
energy 3,5,6 . Meanwhile, the NIF fusion researchers are trying to identify some of these obstacles and addressing the
challenges to getting to ignition 7 .

It is known to fusion scientists that the color phase separation in final optics assembly (FOA) plays a key role in
high-energy and high-peak-power laser systems like the NIF for color management at target that primarily
controls the 3v laser beam conditioning. In ICF laser systems around the world, most of the glass lasers employ
non-linear frequency conversion for converting fundamental wave to its second harmonic and third harmonic
lights 8 . Inevitably, the remnant energy of 1v and 2v frequency lights remains in optical path after frequency
conversion. The unconverted lights as enter fusion target are harmful to ICF experiments, and they should be
filtered out as clean as possible. At present, color phase separation in the NIF is realized through color-separation
gratings (CSGs) in fused silica substrates to transmit 3v light while redirecting unconverted 1v and 2v lights
away from the fusion target 9–11 . However, in fact both the unconverted 1v and 2v lights will continuously
propagate into the target chamber and have a resultant offset focus near the fusion target. The envelope of
unconverted light extends out from target chamber center, potentially affecting the target back lighter structures
and diagnostics 12,13 . Besides these technical problems, the diffractive optical elements used in the FOA that are
made from fused silica glass are always damaged by stimulated Brillouin scattering under high laser fluence 14 . In
addition, to fabricate the large aperture (43 cm 3 43 cm) optics in the FOA, such as color-separation gratings and
silica wedge focus lens, must suffer most harsh processing techniques 11 and therefore is time consuming and

expensive. Now, these related problems due to existing color phase
separation technique, together with the limit of improving the laser
damage resistance of the fused silica glasses, has become one of the
most significant bottlenecks to further increase the output fluence of
ICF laser systems.

As early as in 1999, the NIF council had pointed out that the
catastrophic damage of fused silica at high fluence in a vacuum
fundamentally calls into the question whether fused silica can ever
go the distance to reliable operation at full NIF fluence or above 15 .
Thus they recommended that the effort should be undertaken to
develop some better materials for operation at 8–9 joules/cm 2, and
to determine under what conditions existing materials can operate
reliably at such levels. And the materials should be developed with an
eye towards replacing or protecting the silica optical elements
between the DKDP crystal and the target. To develop replacement
options for fused silica will allow more novel designs for the FOA 15 .

There are a variety of conceptual candidates to replace fused silica,
such as fluoride crystals, fluoride glasses, and others 15, among which
the fluoride-phosphate glasses are verified to the potentially good UV
transmitting materials 16 . On the other hand, because of the increasing demands of the high performance UV transmitting materials to
be applied for lens system in UV microlithography equipments,
excimer laser systems and other special UV optics, since the early
1990’s, researchers has already begin systematic investigations 17–30

on the optical performance of various fluoride-phosphate and other
phosphate-based glasses due to the existence of intrinsic defects,
extrinsic impurity ions or under the irradiations of UV-lamp, excimer lasers, in order to explore the applicability of these glass materials. Recently, we also noticed that a kind of ultraviolet transmitting
near infrared cut filter boron-containing phosphate-based glasses
doped with CuO as absorptive agent 31, which had a high UV transmittance and a low near infrared transmittance were proposed for
the solid-state imaging elements or use in high power lasers for
lithography, laser processing and possible use in laser fusion, but
there is no report of their laser-induced damage property, which is
a necessity for potential use in the ICF laser systems.

In order to solve the above problem relating to the existing color
phase separation technique and meanwhile to explore novel designs
for the FOA in ICF lasers, here we reported a series of new ultraviolet
transmitting, 1v and 2v absorptive fluoride-containing phosphatebased glasses, which are not only highly transparent to the 3v laser
wavelength but selectively intense absorptive to the 1v and 2v laser
lights, therefore 1v and 2v laser lights can be more easily separated
through direct absorption method, which is completely different
from the present color phase separation technique using the color
separation gratings. More worthy of mention is the proposed
phosphate-based glasses also maintain excellent performance in resistance to nanosecond pulse laser-induced damage, for which the
laser-induced surface damage threshold and growth damage threshold at 351 nm (8 ns@3v) is testified to be as high as that of fused
silica and even higher. At relative lower laser beam fluence the new
phosphate-based glass has a comparable damage growth rate with
that of the fused silica, and under larger beam fluence irradiations its
damage grows faster than fused silica. It may suggest that the 3v
transparent fluoride-containing phosphate-based glass should have
high comprehensive resistance to nanosecond pulse laser-induced
damage, which is better than or at least compariable with that of the
fused silica under the same boundary conditions. From the systematic analysis in this work, it suggests that their high 3v laser-induced
damage threshold is attributed to the special laser-induced fluorescence character that was verified through contrast experiments
can be realized through special tailoring on the glass structure.

Results
Spectroscopic property and laser-induced damage thresholds of
the series of phosphate based glasses Fig 1 shows the spectroscopic

and laser-induced damage probability of the series of phosphatebased glasses with specially tailored structure. As seen from Fig. 1a,
the glasses maintain high 3v (351 nm) internal transmittance
(t351 nm). The t351 nm reaches up to 99.5% for the 3v transparent
glass, and it is about 98.6% and 99.2% for the 1v and 2v absorptive
glass, respectively. The internal transmittance at 1053 nm (t1053 nm)
is as low as 0.14% for the 1v absorptive glass and the internal
transmittance at 527 nm (t527 nm) is about 0.51% for the 2v
absorptive glass.

Besides the feature of intense absorption towards 1v or 2v laser
lights, these phosphate-based glasses also possess excellent performance of damage resistance to nanosecond pulse laser irradiation. As
shown in Fig. 1b, the LIDT values (8 ns@3v) corresponding to zero
damage probability of the 3v transparent glass at 351 nm laser wavelength is 13.5 J/cm 2, but it is 6.3 J/cm 2 for the fused silica. The 2v
absorptive glass has a LIDT value of 17.6 J/cm 2 at 527 nm, and it is
16.5 J/cm 2 for the fused silica (Fig. 1c). As can be seen from Fig. 1d,
only at the wavelength of 1053 nm, the LIDT value of the 1v absorptive glass is (36.6 J/cm 2 ) is relatively lower than that of the fused silica,
45.1 J/cm 2 .
The contrast LIDT test (8 ns@3v) results in Fig. 1e indicate that,
under the irradiation of 351 nm pulse laser, the LIDT value corresponding to zero damage probability of the series of phosphate-based
glasses on the rear surface decreases in the order of the 3v transparent glass (13.5 J/cm 2 ), the 2v absorptive glass (12.7 J/cm 2 ) and the
1v (12.5 J/cm 2 ) absorptive glass, which is due to the increasing
absorption coefficient at the 3v wavelength. And each value is nearly
twice that of the fused silica (6.3 J/cm 2 ). As irradiated by 527 nm
nanosecond pulse laser, it is viewed that the LIDT values of these
glasses (23.3 J/cm 2, 17.6 J/cm 2 and 19.8 J/cm 2 for the 3v transparent,
2v and 1v absorptive glasses, respectively) are also higher than that
of fused silica (16.5 J/cm 2 ). Furthermore, the zero probability LIDT
at 1053 nm increases to 53.5 J/cm 2 and 47.8 J/cm 2 for the 3v transparent glass and the 2v absorptive glass, respectively. Generally, the
more intense absorption of the material at the laser wavelength, the
easier it will be damaged by the laser due to more serious thermal
effects. Therefore, it is reasonable that the zero probability LIDT at
3v wavelength is high because of the higher 3v internal transmittance, i.e. lower absorption coefficient at 3v wavelength. However,
the series of glasses generally exhibit higher LIDT as compared with
that of fused silica glass, except in the case of 1v absorptive glass
under 1053 nm laser irradiation.

Laser-induced fluorescence (LIF) and its effect on the laserinduced damage threshold (LIDT). More interesting, we
occasionally found that the series of glasses display distinct
fluorescent characteristics during their LIDT experiments. As
shown in Fig. 2a–c, yellowish-orange laser-induced fluorescence
are captured by the panchromatic camera, and the fluorescence
intensity of their corresponding 8 th frame as indicated by the high
speed monochrome camera photographs differs largely for these
three glasses (Fig. 2d–f). By means of the high speed monochrome
camera, the decay times of the laser-induced fluorescence are
estimated to be as long as tens of millisecond and the estimated
decay time of the 1v absorptive glass is much longer than that of
the 3v transparent and 2v absorptive glass. The corresponding laserinduced fluorescence spectra are shown in Fig. 2g–i. Under the
351 nm laser irradiation, one broad fluorescence band centered
close to 600 nm is observed for the 1v absorptive glass, and the
fluorescence peak position shift to about 776 nm for both the 3v
transparent and the 2v absorptive glass but their fluorescence
intensity become relative weak.

For further investigation on the interrelation between LIF and
LIDT, first we have taken contrast experiments on the 3v transparent glass that has no absorption towards 1v or 2v light. Fortunately,
we found that the 3v transparent glass which was prepared in an

Figure 1 | Spectroscopic and damage resistance properties of the series of phosphate-based glasses with specially tailored structure. (a) Internal
transmission spectra. Each sample has a path length of 10 mm, both surfaces uncoated. (b)–(e) Zero damage probability of the series of phosphate-based
glasses and fused silica (with a thickness of 7 mm, uncoated) under different laser irradiation wavelengths: (b) 3v transparent glass and fused silica at
351 nm, (c) 2v absorptive glass and fused silica at 527 nm, (d) 1v absorptive glass and fused silica at 1053 nm, and (e) comparison of the laser-induced
damage threshold between the phosphate-based glasses and fused silica glass under three laser irradiation wavelengths.

ambient air atmosphere did not show any visible fluorescence under
the 351 nm laser shots, as indicated in Fig. 3a, but in clear contrast
the laser-induced fluorescence is notable for the 3v transparent glass
prepared in a special reducing atmosphere. Accordingly, the former’s
LIDT at 351 nm (8 ns@3v) was measured to be 8.4 J/cm 2, which is
much lower than that of the latter one (13.5 J/cm 2 ). For easy comparison, hereafter the 3v transparent glass prepared in the special
reducing atmosphere is named as the 3v transparent glass with
tailored structure and the one melted in an ambient air atmosphere
labeled as the 3v transparent glass without tailored structure.

From the above significant change of LIDT with its different fluorescent character for the 3v transparent glasses, it is clear to see that
the fluorescence is an important factor contributing to the glasses’
high laser-induced damage threshold. We further deduced that the
striking decrease of the LIDT value, which depends on the glass’s
fluorescence character rather than the glass composition, most probably originates from their difference in the glass structure. It is clear
that further research leading to a better understanding of the glass
structure will continue to benefit development of the glasses with
high LIDT values

Glass structure characterization and micro-defects analysis for the
3v transparent glasses. What kind of difference in the structure or
micro-defects inside the glasses will lead to the apparent contrast in
the fluorescence character? Firstly, it is observed that the ultraviolet
absorption edge of the former one shifts to the long wavelength side
obviously even the transmittance at 351 nm changes very little
(Fig. 3b). Because the reducing glass melting atmosphere
suppressed the formation of Fe 31 impurity and defects in the glass
that have absorption in the ultraviolet region. These are very small
fluoride contents in these glasses, and the fluoride will be evaporated
during the glas melting process. So we have examined the glass
especially with respect to the fluoride concentration of the two asprepared 3v transparent glass samples with and without specially
tailored structure by means of the energy dispersive spectrometer
(EDS). The EDS spectra are shown in Fig. 3c and comparative
analyses of the elemental composition in the two samples are
presented in Table 1. As EDS is not very sensitive to the light
elements with an atomic number smaller than boron (B), the
lithium (Li) element is not found here. The EDS spectra of the asprepared glasses still indicates the presence of the fluoride element in

Figure 2 | Laser-induced fluorescence phenomenon of the series of phosphate-based glasses under the 351 nm pulse laser irradiation. (a)–(c) Captured
synchronously by a panchromatic camera, (d)–(f) Captured synchronously by a high speed monochrome camera for the 3v transparent glass, 1v
absorptive and 2v absorptive glass, respectively. (g)–(i) Laser-induced fluorescence spectra for the series of glasses.

the glass after the long time duration at the high melting temperature
(1200uC). As seen from Table 1, with regard to the fluoride content in
the two undoped phosphate-based glass (3v transparent glass), it is
4.88 wt% and 3.36 wt% for the glass that was melted in a closed
iraurite crucible in a reducing atmosphere and the one in a silica
crucible at the ambient air atmosphere, respectively. It is regarded
that the closed melting conditions in the iraurite crucible to some
extent prohibits the evaporation of fluoride. As the glass was melted
in a silica crucible, Si was introduced due to the crucible corrosion.
For the Raman spectra (Fig. 3d), the first broad peak in the low
wavenumber region between 200–600 cm 21 is due to complex
internal deformation bending modes of phosphate chains (both in
chain PO2 and O-P-O bending). Peaks at,706 cm 21 are assigned to
the P-O-P symmetric stretching (Q 2 ) mode of bridging oxygens
between two phosphate tetrahedra, (POP)sym. The most intense
peaks at,1202 cm 21 indicate the symmetric resonances
associated with the O-P-O non-bridging oxygens on Q 2 phosphate
tetrahedra, (PO2)sym. The small peak at,1262 cm 21 that sits on the
shoulder of the,1202 cm 21 peak is the asymmetric stretching of
non-bridging oxygens on Q 2 phosphate tetrahedra, (PO2)asym. And
no (PO3)sym stretching (Q 1 ) mode or (PO4)sym stretching (Q 0 )
mode of the P-O-P linkage which is supposed to be near 1030–
1100 cm 21 and 990–1010 cm 21 respectively is observed in the
Raman spectra 32,33 . The 31 P NMR spectra (Fig. 3e) of the two types
of 3v transparent glasses further reveal their difference in the fine
glass structure. The chemical shifts peaks near,31 ppm,,20 ppm
and,13 ppm are related to metaphosphate (Q 2 ) tetrahedron 34 and
those near,7 ppm and,2 ppm are assigned to pyrophosphate
(Q 2 ) tetrahedron 35 .

In further experiments, we have investigated their absorption
spectra through Gaussian peak fitting method and ESR spectra, in

order to detect the impurity or micro defects in these glasses, which
are always the essential origin of a fluorescence emission. Fig. 4a and
Fig. 4b present the Gaussian peak fitting of the absorption spectra for
those two 3v transparent glasses with and without specially tailored
structure, respectively. The absorption peaks identified from the
Gaussian peak fitting of the absorption spectra are shown in Table 2.

The O1s X-ray photoelectron spectra (XPS) collected from these
two glasses are given in Fig. 4c and Fig. 4d. The XPS spectra were
decomposed into a sum of Gaussian components in order to evaluate
the bridging-to-terminal oxygen ratio in these two different glasses.
The O1s spectra are best fitted with three or four Voigt peaks, indicating the bonding of oxygen atoms is complicated. The bands peaking at the lower binding energy (,531–535 eV) are assigned to the
non-bridging oxygen (NBO) bonding to the glass modifier ions, and
the peak at the higher binding energy (,536 eV) is related to
bridging oxygen (BO) bonding to the glass former ions in the glass
network 36, representing distinct P 5 O, P-O-R 1 /R 21 and P-O-P, etc.
In addition, the EPR spectra of these two 3v transparent glasses after
3v laser irradiation are measured (Fig. 4e). After laser irradiation, the
3v transparent glass without tailored structure shows a typical character of POHC defects in EPR spectra 22,37, which indicate the easier
formation of POHC defects for this type of glass under the 3v laser
irradiations.

At last, we have further measured the growth damage and bulk
damage properties of the fluoride-containing phosphate-based glass
(3v transparent glass), as shown in Fig. 5. In this stage we can only get
a rough view of the growth damage property of the new phosphatebased glass, which is calculated to be about 6.5 J/cm 2 (8 ns@3v)
through the x-intercept of plot of growth coefficients vs. beam fluence, as shown in Fig. 5a. The fitted slope of the data in Fig. 5a is
about 0.075 per shot per J/cm 2 . The bulk damage threshold (8 ns@

Figure 3 | Contrast investigations on the 3v transparent glasses with and without specially tailored structure. (a) Laser-induced fluorescence spectra,
(b) The transmission spectra (with Fresnel reflection), (c) EDS spectra, (d) Raman spectra and (e) 31 P nuclear magnetic resonance (NMR) spectra.

351 nm) of the 3v transparent phosphate-based glass is measured to
be about 9.6 J/cm 2, as shown in Fig. 5b), which is lower than that of
the fused silica (14.1 J/cm 2 ) measured under similar conditions.

Discussion
For the two absorptive samples, the 3v internal transmittance
decreases compared with that of the 3v transparent glass, and their
transmission edges in the UV spectral range shift both toward the
long-wavelength. The red-shift of UV transmission edge is due to the
doping of the absorptive ions in the absorptive glasses, i.e. Co 21 and
Fe 21, which present different degrees of effect on the UV absorption
and therefore make the internal transmittance at 351 nm variant.
The trivalent ions of the 1v absorptive ions, i.e. Fe 31 have obvious
absorption in UV and near-UV range, but the 2v absorptive ions

(Co 21 ) don’t 38 . Thus the 1v absorptive glass shows a much larger redshift value than the 2v absorptive one.

However, the attention should also be paid that the 3v absorptive
coefficient will increase with higher doping levels of these absorptive
ions. So a balance must be made between the 3v internal transmittance and the specific absorptive coefficient at 1v and 2v laser wavelength. For example, with regard to the 1v absorptive glass, the
optical absorption at 1053 nm is due to Fe 2125,26 . Therefore, the contrast result in Figure. 1d that 1v absorptive glass’s laser-induced
damage thresholds at 1053 nm is lower than that of fused silica glass
is attributed to its serious absorption of the 1053 nm laser light,
which contributed to a more intense thermal damage 39 . Previous
investigations on some aluminum potassium barium phosphate
glasses indicate that the optical absorption at 1053 nm is due to

Table 1 | Comparative analyses of the elemental composition in the two 3v transparent glass samples with and without specially tailored
structure by means of the energy dispersive spectrometer (EDS)

Glass O F P K Mg Ba Al Y La Si

3v glass(tailored) 45.98 4.88 15.35 3.73 0.61 9.27 2.01 16.17 2.01 0
3v glass(nontailored) 47.49 3.36 14.07 3.80 0.48 9.68 2.24 16.39 1.90 0.59

Figure 4 | The absorption spectra, X-ray photoelectron spectra (XPS) and electron paramagnetic resonance (EPR) spectra for the 3v transparent glasses
with and without specially tailored structure: (a), (b) Absorption spectra with Gaussian peak fittings, (c), (d) O1s XPS spectra, and (e) EPR spectra of the
3v transparent glasses after 3v laser irradiations.

the change of Fe 21 /Fe 31 ratio in the glasses, which depends on a shift
in the redox equilibrium between Fe 21 and Fe 31 that changes with
the composition and the oxygen activity. The latter is related closely
to the redox states of melting 27, glass composition 25, melting temperature 28, oxidizing and reducing additives to the raw materials.
Therefore, the balance between the internal transmission at 3v
and 1v/2v absorption coefficient can be realized through adjusting
the doping concentration of absorptive ions in the glass batches and
the control of the glass melting environment and other melting
parameters.

With regard to the UV transmittance, as compared with the copper doped phosphate filter glasses 31, here the investigated phosphate

based glasses show much higher 3v internal transmittance and a
blue-shift of the ultraviolet absorption edge, which is due to the
introduction of fluorides and the reducing melting atmosphere that
suppress the influence of Fe 31 impurity on the glasses’ ultraviolet
absorption. In addition to their featured absorption, the 1v absorptive glass can also absorb little amount of the 2v light, and the 2v
absorptive glass also shows much stronger absorption to the 1v light.
The features of ultraviolet (3v) transmitting but intense absorption
to 1v and 2v laser lights for these two phosphate-based glasses
endow them with evident merits of selective absorption towards
1v and 2v laser wavelength light, respectively. If we can replace
the color-separation grating optics in the FOA with the 1v and 2v

Table 2 | Absorption peaks identified from the Gaussian peak fitting of the absorption spectra for the two 3v transparent glasses with and
without specially tailored structure

Phosphor electron hole centers Phosphor oxygen bonded hole center Impurity related defects
Glass

PO2-EC (eV) PO3-EC (eV) PO4-EC (eV) POHC (eV) Fe 31 (eV)

3v glass (tailored) 4.56 5.86 5.60 5.25 5.06 - 3v glass (nontailored) 4.51 5.94 - 5.14 5.04 2.22 4.77

Figure 5 | The growth damage and bulk damage properties of the fluoride-containing phosphate-based glass (3v transparent glass): a) Measured
exponential growth coefficient and b) Bulk damage probability as a function of beam fluence.

absorptive optics, it is possible to filter the unconverted 1v and 2v
lights clean after the 3v laser light passes these two filter glasses.

The endowment of the selectively absorptive feature at 1v and 2v
laser wavelength but meanwhile especially higher LIDT performance
prior to the fused silica glass gives these two absorptive glasses potential high specific color phase separation ability by directly absorbing
the 1v or 2v wavelength lights and therefore makes the 1v and 2v
lights be separated from the 3v laser light. Thus, using these new
glass materials as color separation optics, just like the color separation gratings presently used in the US NIF 40, it can also make the
minimum NIF specifications satisfied that for transmitting .95% of
3v light and,5% of 1v and 2v light, to the zero order. At the same
time, to process the parallel-plate optics will not suffer so many
processing difficulty compared with making the color separation
gratings or silica wedge focus lens used in the US NIF.

For further analysis on the glass structure difference of the 3v
transparent glasses, firstly, the Raman signals measured for those
two glasses (Fig. 3d) indicate their glass networks base mainly on
Q 2 tetrahedra, i.e. the basic structure for these 3v transparent glasses
can be described as a network of metaphosphate tetrahedral that are
linked together through covalent bonding of oxygen atoms to form
very long metaphosphate chains 32,33 . And the NMR spectra (Fig. 3e)
in further suggest that both Q 2 and Q 2 phosphate related species are
evident in these two 3v transparent glasses. The most distinct difference is that the peak near,31 ppm disappears for the 3v transparent glass without tailored structure. This obvious decrease in
shielding (less negative chemical shift) suggests a decreasing polymerization tendency of the glass network from the main component
of metaphosphate tetrahedrons to pyrophosphate tetrahedrons to
some extent. Therefore, the 3v transparent glasses with tailored
structure have relatively more densified glass network as compared
with the ones without tailored structure.

Analyzed from the Gaussian peak fitting of the absorption spectra
(Fig.4a and b), phosphor electron hole centers including PO2-EC,
PO3-EC and PO4-EC are detected from both the 3v transparent glass
samples. Phosphorous oxygen bonded hole center (POHC) and Fe 31

related defects absorption 41 are confirmed by the fitted absorption
band at about 2.22 eV (558.8 nm) and 4.77 eV (260.0 nm), but only
for the 3v transparent glass without tailored structure (see Table 2).
It is also regarded that the special reducing glass melting atmosphere
helped decrease the POHC and Fe 31 related defects in the 3v transparent glass, which directly results in the blue-shift of the ultraviolet
absorption edge as indicated in Fig. 3b. On the other hand, the
addition of polyvalent ions, e.g. Co 21 or Fe 21 can suppress the coloring effects due to the POHC formation, which absorb in the visible
spectral range 41 . That is why the red-shift of the UV transmission
edges for these two absorptive glasses is not so large.

From the XPS spectra in Fig. 4c and d, the ratio of the bridging
oxygens to the total oxygens in the glasses BO/(BO 1 NBO) that is

calculated referring to the method by M. Karabulut et al. 36, varies
slightly. It decreases from 0.15 for the 3v transparent glass with
tailored structure to 0.13 for the one without tailored structure.
This confirms the NMR analysis from another side that the 3v transparent glass with tailored structure have more densified glass network due to the increase of bridged oxygens, compared with the one
without tailored structure.

The 3v transparent glass without tailored structure has more
POHC and Fe 31 related defects but no visible fluorescence and is
more prone to form POHC defects under the 351 nm laser irradiation, and the key point is that it has much lower LIDT value, as
compared with the one with tailored structure. Thus, we can generally come to a conclusion by considering the above experimental
facts that a notable laser-induced fluorescence results in a high LIDT
value for the 3v transparent glass, and the fluorescence band at
,776 nm does not originate from the POHC or Fe 31 related defects
inside the glasses but should be closely related with the glass’ special
structure.

With regard to the laser-induced damage mechanism of these
phosphate-based glasses, from present study results, we can come
out a hypothesis that under the laser irradiations, the photons have
direct interactions with these glasses to produce the original heat
energy, the dense glass structure are not very easily to be broken
apart under the laser irradiation, at the same time it can release part
of the absorbed laser energy through the radioluminescence process,
especially on the surfaces, thus to mitigate the direct deposited heat
induced damage for these glasses, leading to the improvement of
their resistance to the laser-induced surface damage. It needs more
detailed work to analyze the contribution of the heat release by means
of laser induced fluorescence among those heat mitigation methods.

It can be found that the growth damage threshold of the phosphate-based glass is larger than that of the fused silica 46, which is
about 5.0 J/cm 2 . However, the fitted slope of the data in Fig. 5a is as
large as about 0.075 per shot per J/cm 2 . It is much higher than that of
the fused silica 46 that is between 0.03 and 0.05 per shot per J/cm 2 . It
can be found that the exponential coefficients corresponding to a
fluence of 8.0 J/cm 2 are very close for the fluoride-containing phosphate-based glass and fused silica, under which the new phosphatebased glass maintains a relative smaller growth rate. However, its
growth coefficient increases more rapidly as the beam fluence is
larger than 8.0 J/cm 2, and the value almost doubles as beam fluence
increases from10.0 J/cm 2 to 14 J/cm 2 . It suggests that at relative
lower laser beam fluence the new phosphate-based glass has a comparable damage growth rate with that of the fused silica, and under
larger beam fluence irradiations its damage grows faster than fused
silica.

The bulk damage threshold (8 ns@351 nm) of the 3v transparent
phosphate-based glass is measured to be about 9.6 J/cm 2, which is
lower than that of the fused silica (14 1 J/cm 2 ) measured under sim

ilar conditions. This may have close relationship with the laserinduced fluorescence observed in the bulk of these fluoridecontaining phosphate-based glasses. It is thought that the effect of
the radioluminescence process to release part of the absorbed laser
energy and mitigate the direct deposited heat induced damage in the
bulk of these glasses will become less important as compared with the
condition of rear surface damage. On the contary, the influence of
defects should be stressed. Gnerally, a luminescence phenomenon
indicates the presence of some defects in the materials. These fluoride-containing phosphate-based glasses have multi-components
including alkaline and alkali earth metals, thus sufficient P-O-R 1 /
R 21 bonds will exist together with the P 5 O and P-O-P bonds in the
glasses. The former’s bonding strength is weaker compared with that
of the latter ones, thus it is much weaker than that of the Si-O bonds
in the fused silica glasses. Compared with the fused silica glass, the
complex and non-perfect glass structure of these fluoride-containing
phosphate-based glasses make them more liable to produce large
amount of new defects in the bulk under the high dose of laser
irradiation, which contributes to their lower bulk damage threshold.
Besides, the researches on the other contributing factors, for instance
the nonlinear refrective index and self-focusing, the mechnical and
thermal properties of the glasses, etc, are underway.

In addition, under the same experimantal conditions, the bulk
damage threshold of the 3v transparent fluoride-containing phosphate-based glass is near 70% of that of the examined fused silica,
but its surface damage threshold and growth damage threshold is
higher than those of fused silica. By considering these factors comprehensively, we think the 3v transparent fluoride-containing phosphate-based glass should have high resistance to nanosecond pulse
laser-induced damage, which is better than or at least compariable
with that of the fused silica under the same boundary conditions.
Comprehensive test of these fluoride-containing phosphate-based
glasses on the SG-III prototype system is under consideration.

Finally, even these phosphate-based glasses have shown some
advantages over fused silica, it deserves attention that there still exist
some drawbacks to overcome. Such as, the luminescence restricts
them being used in other fields like UV microlithography, and they
are difficult to manufacture in large aperture in industry. There is lots
of work to be done. For example, to further increase their UV internal
transmittance through improving the purity of raw materials, to
confirm the interrelation between the laser-induced fluorescence
with the glasses’microstructure and configurations in order to
deplete the laser induced defects by means of the material structure
engineering, and finally to regulate the glass composition and
develop the appropriate continuous melting technology for producing the series of glasses in industry, etc. It demands many
cooperative efforts before these types of fluoride-containing phosphate-based glass materials are developed to fulfill the requirements
for engineering applications in ICF systems.

We have engineered a new series of ultraviolet transmitting, 1v
and 2v absorptive fluoride-containing phosphate-based glasses with
high pulse laser-induced surface damage thresholds. The 1v and 2v
absorptive glasses are capable of separating third harmonic frequency from the fundamental and the second harmonic frequencies
through selectively direct absorption, and their improved high
damage threshold to the 351 nm nanosecond laser pulses, compared
to standard fused silica glasses, is noteworthy. Use of these high
performance glasses as color separation optics in ICF laser systems
will be a radical departure from conventional color separation
approaches by means of fused silica CSGs, thus novel designs of
the FOA will be achieved. The studies on the relations between the
laser-induced fluorescence, laser-induced damage threshold and the
glass structure indicated that the laser induced fluorescence property
is closely related to the glass structure, and it is a key factor that
conduces to the high laser-induced damage resistance of the series
of glasses

Methods
Preparation of the fluoride-containing phosphate-based glasses. The undoped
phosphate-based glasses (3v transparent glasses) with little content of fluoride were
prepared as references with high purity raw materials having a weight composition
(wt%) of (0.5-2)Li2O-(3-5)K2O-(3-5)MgO-(7-10)BaO-(8-11)
Al2O3-(59-64)P2O5-(0-1)YF3-(0-2)LaF3. The iron and cobalt ions as 1v and 2v
absorptive agents are introduced into the 3v transparent glasses to produce the 1v
and 2v absorptive glasses, respectively. The series of fluoride-containing phosphatebased glasses were prepared in a 1.2 L iraurite crucible under reducing H2/N2
atmosphere to endow them with specially tailored material structure. In contrast, the
3v transparent glass with same composition was intentionally made in an ambient air
atmosphere in a 1.2 L silica crucible, which was named as the one without tailored
structure, in order to compare its glass structure with that of the above glasses
prepared in reducing atmosphere. For preparation of the samples, the mixed raw
materials with each weight of 2600 g were melted in a 1.2 L iraurite crucible or silica
crucible at 950uC. And the glass melts were refined and homogenized through
mechanical stirring at 1200uC for 120 min and then cooled down to 980uC within
60 min. the homogenized glass melts were cast into a mold preheated at 300uC, then
annealed at 400uC through a precision annealing process with a cooling rate of 0.2uC/h from 400uC to 300uC, followed by -1uC/h from 300uC to 150uC.

Spectral characterization. Transmission spectroscopy measurements of the glass
samples were carried out with a UV-VIS-NIR spectrophotometer (Shimadzu UV3101) and the internal transmittance at investigated wavelength (tl) was achieved
using two polished samples of the same glass but with different thickness (5 and
15 mm for each one) to compensate for Fresnel surface losses. Raman spectra were
collected with a Jobin-Yvonne LabRam microscope with a 514 nm laser excitation in
the range of 100–1600 cm 21 . The 31 P nuclear magnetic resonance (NMR) spectra were
acquired at room temperature on Bruker MSL 360 and Chemagnetics CMX 240
spectrometers at 121.4 MHz using a 9.4 T magnet at typical spinning frequencies of
10 kHz. Analyses of the elemental composition in the two 3u` transparent glass
samples with and without specially tailored structure were carried out by means of the
energy dispersive spectrometer (EDS). The X-ray photoelectron spectroscopy
measurements were conducted on a Thermo Advantage X-ray photoelectron
spectrometer (XPS) at room temperature using Al Ka (1486.6 eV) as the radiation
source. The acceleration voltage was 12 kV, and the emission current was 10 mA.
Electron paramagnetic resonance (EPR) spectra were recorded at 100 K using a
Bruker EMX spectrometer operating in the X-band frequency (9.677 GHz) with field
modulation 100 kHz. The microwave power used was 20 mW.

Laser-induced damage thresholds and laser-induced fluorescence measurements.
The precision annealing glass samples were cut into 25 mm 3 25 mm 3 7 mm for
the surface LIDT measurements and precisely polished using zirconia (ZrO2) microparticles. Here nonuse of cerium polishing power (CeO2) is because it has large
influence on the laser-induced damage at 351 nm due to its strong absorption of the
ultraviolet light 42,43 . After precision polishing, the glass samples were measured to
have a parallelism less than 19, a surface flatness with,l/6 at 632.8 nm in the 90%
area of central aperture and high surface quality with 20–10 scratch-dig. The surface
roughness (Rq) of these samples was about 0.8 nm. All the samples used for the LIDT
measurements had no any coating in both surfaces.

1-on-1 laser induced surface damage studies of these investigated glasses were
carried out using a Q-switched Nd-glass pulse laser according to ISO 11254-1 44,
which provided the test beam of 351 nm, 527 nm and 1053 nm with a pulse width at
half maximum of 8–12 ns. The laser beam of 1053 nm was first generated at a small
aperture master oscillator stage and amplified to several joules using Nd doped laser
glass. The fundamental frequency light was then converted to its second harmonic
(527 nm) and third harmonic (351 nm) lights through the frequency converters
(KDP crystals). The incident beam energy was measured in proportion by a calibrated
energy probe (Ophir PE50BF) before the test sample with a silica wedge. The laser
energy ratio of sample to power meter was 26.3. The peak energy density fluctuation
was,5%. A lens with the focus length of 1498 mm was used to focus the laser on the
rear surface of the measured samples. The profile of the pump beam is near-Gaussian
with 1/e 2 diameter of about 4.12 mm, 3.63 mm and 2.56 mm at 1053 nm, 527 nm
and 351 nm on the rear surface of the glass sample. The damage of the measured
samples was diagnosed by a real time observation system composed of a 3 megapixel
CCD camera and a set of long working distance objectives in dark field mode. The
damage was defined to be any visible change in the laser irradiated site by measurement of the scattering light under the dark field. Per fluence, at least ten laser shots
were tested at separate sites. Repeat this procedure for other pulse energies to develop
a plot of damage probability versus laser fluence. Linear extrapolation of the damage
probability data to zero damage probability yields the threshold laser fluence for each
sample. Fused silica samples that have the same thickness (25 mm 3 25 mm 3
7 mm) and similar surface polishing level were used as reference material under
similar excitation conditions.

The damage growth on the rear surface of the 3v transparent glass was parameterized by the growth threshold (Fth) and the measured growth coefficient (a) 45 . The
growth coefficient was obtained through an exponential growth fitting of the damage
area as a function of the beam fluence (F) 46 . The laser damage was initiated at 351 nm
with a single shot at laser pulse fluence levels of about 25 J/cm 2 and the increase in
damage area was measured in terms of gray scaling due to subsequent shots at lower
fluence

The bulk damage threshold of the 3v transparent glass and the fused silica were
measured using a Q-switched Nd-YAG laser with a 9.3 ns FWHM Gaussian pulse at
355 nm by means of an R-on-1 measuring mode. The pump beam is near-Gaussian
with 1/e 2 diameter of about 13 mm after the spatial filtering. The precisely polished
samples with size of 50 mm 3 50 mm 3 20 mm were used. The laser beam was
focused with a lens of 70-cm focal length and the focal plane was 26 cm apart from the
rear surface of the sample. Change in the laser irradiated site in the bulk near the rear
surface was observed by a CCD for determination of the bulk damage in the testes
samples.

The laser-induced luminescence phenomenon was captured synchronously during
the LIDT experiments by a digital panchromatic camera (30 frames per second) and a
Phantom v9.1 high speed digital camera (500 frames per second), respectively. The
laser-induced fluorescence spectra were investigated by setting a time-resolved fiber
spectrometer (ANDOR TECHNOLOGY SR-303i) aside the tested samples perpendicular to the laser beam propagation path and recorded with a CCD (DU-897E-CS0#BV) from a side view. A high-bandpass filter (at 400 nm) was set up in the front of
the fiber spectrometer to avoid the incoming light of the 351 nm laser beam. The
details of the experimental setup of the LIDT and LIF testing system referred to our
previous research 47 .

1. Hand, E. Laser fusion nears crucial milestone. Nature 483, 133–134 (2012).
2. Miller, G. H., Moses, E. I. & Wuest, C. R. The National Ignition Facility: enabling
fusion ignition for the 21 st century. Nucl. Fusion. 44, S228–S238 (2004).
3. Clery, D. The NIF breakthrough that wasn’t. Science 342, 295 (2013).
4. Hurricane, O. A. et al. Fuel gain exceeding unity in an inertially confined fusion
implosion. Nature 506, 343–348 (2014).
5. Moses, E. I. et al. The National Ignition Campaign: status and progress. Nucl.
Fusion. 53, 104020 (2013).
6. Brumfiel, G. Ignition switch. Nature 491, 159 (2012).
7. Brumfiel, G. Laser lab shifts focus to warheads. Nature 491, 170 (2012).
8. Dixit, S. N. et al. Color separation gratings for diverting the unconverted light
away from the NIF target. SPIE, 3047, 463–470 (1997).
9. Honig, J. et al. Optics performance at 1v, 2v, and 3v: final report on LDRD
Project 03-ERD-071, February 7, 2006.
10. Doskolovich, L. L. et al. Design and investigation of color separation diffraction
gratings. Appl. Opt. 46, 2825 (2007).
11. Dixit, S., Menapace, J., Yu, J., Britten, J. & Hyde, R. Large-aperture diffractive
optical elements for high power laser and space applications, in Diffractive Optics
and Micro-Optics, Rochester, New York, October 10, 2004.
12. Moody, J. D. et al. Backscatter measurements for NIF ignition targets (invited).
Rev. Sci. Instrum. 81, 10D921 (2010).
13. Ahmed, M. et al. X-ray diffraction diagnostic design for the National Ignition
Facility. Proc. SPIE 8850, Target Diagnostics Physics and Engineering for Inertial
Confinement Fusion II, 88500N ( September 26 2013).
14. Parham, T. G. et al. Large aperture optics performance. Livermore, CA, LLNL-TR410955, (February 25 2009).
15. John, L. E., William, F. K., William, W. S. & Clive, G. W. NIF Technology Review,
from technology resource group of the NIF council, Nov. 4, 1999.
16. Natura, U., Feurer, T. & Ehrt, D. Kinetics of UV laser radiation defects in high
performance glasses. Nucl. Instrum. Methods Phys. Res., Sect. B 166–167, 470–475
(2000).
17. Kitamura, N., Hayakawa, J. & Yamashita, H. Optical properties of
fluoroaluminate glasses in the UV region. J. Non-Cryst. Solids 126, 155–160
(1990).
18. Ehrt, D. & Seeber, W. Glass for high-performance optics and laser technology.
J. Non-Cryst. Solids 129, 19–30 (1991).
19. Duffy, J. A. Charge transfer spectra of metal ions in glass. Phys. Chem. Glasses 38,
289–292 (1997).
20. Zou, X. & Toratani, H. Radiation resistance of fluorophosphate glasses for high
performance optical fiber in the ultraviolet region. J. Appl. Phys. 81, 3354–3362
(1997).
21. Hosono, H. et al. Solarization of AlF3-based fluoride glasses for VUV optics by
ArF excimer laser irradiation. SPIE 3424, 146–156 (1998).
22. Ehrt, D., Ebeling, P. & Natura, U. UV transmission and radiation-induced defects
in phosphate and fluoride-phosphate glasses. J. Non-Cryst. Solids 263&264,
240–250 (2000).
23. Natura, U. & Ehrt, D. Generation and healing behavior of radiation-induced
optical absorption in fluoride phosphate glasses: The dependence on UV
radiation sources and temperature. Nucl. Instrum. Methods Phys. Res., Sect. B 174,
143–150 (2001).
24. Campbell, J. H. Damage resistant optical glasses for high power lasers: A
continuing glass science and technology challenge. First International Workshop
on Glass and the Photonics Revolution, Bad Soden, Germany, 27–29 May, 2002.
25. Ehrmann, P. R. et al. Optical loss and Nd31-non-radiative relaxation by Cu, Fe,
and several rare earth impurities in phosphate laser glasses. J. Non-Cryst. Solids
263&264, 251–262 (2000).
26. Ehrmann, P. R. & Campbell, J. H. Nonradiative energy losses and radiation
trapping in neodymium-doped phosphate laser glasses. J. Am. Ceram. Soc. 85,
1061–1069 (2002).
27. Arbuzov, V. I., Voroshilova, M. V., Gusev, P. E., Nikitina, S. I. & Fedorov, Y. K.
Influence of the redox conditions of melting on the quantitative ratio of ions

Fe21/Fe31 in aluminum potassium barium phosphate glass. Glass Phys. Chem.
33, 556–561 (2007).
28. Arbuzov, V. I. & Gusev, P. E. Influence of the melting temperature and rate of
cooling the melt to the glass making temperature on the redox equilibria Fe 21 «
Fe 31 and Cu 1 « Cu 21 in aluminum potassium barium phosphate glasses. Glass
Phys. Chem. 35, 463–467 (2009).
29. Gusev, P. E. et al. Effect of coloring impurities on the absorption in neodymium
phosphate laser glass at a lasing wavelength. Glass Phys. Chem. 32, 146–152
(2006).
30. Arbuzov, V. I., Semenov, A. D., Fedorov, Y. K. & Gusev, P. E. Influence of melting
conditions on the equilibrium of copper ions in aluminum potassium barium
phosphate glass. Opt. Zh. 74, 54–59 (2007).
31. Ogawa, T., Koike, A., Kondo, Y. & Ohkawa, H., inventors; Asahi Glass Company
Ltd., assignee. Ultraviolet transmitting near infrared cut filter glass. United States
patent US 2013/0105744 A1. 2013 May 2.
32. Brow, R. K. Review: the structure of simple phosphate glasses. J. Non-Cryst. Solids
263&264, 1–28 (2000).
33. Fletcher, L. B. Photonic device fabrication inside phosphate glasses using
femtosecond laser waveguide writing techniques. Ph. D. Dissertation, University
of California, Davis, 2011.
34. Turner, G. L., Smith, K. A., Kirkpatrick, R. J. & Oldfieldt, E. Structure and cation
effects on phosphorus-31 NMR chemical shifts and chemical-shift anisotropies of
orthophosphates. J. Magn. Reson. 70, 408–415 (1986).
35. Brow, R. K., Kirkpatrick, R. J. & Turner, G. L. The short range structure of sodium
phosphate glasses I. MAS NMR studies. J. Non-Cryst. Solids 116, 39–45 (1990).
36. Karabulut, M. et al. X-Ray photoelectron and mo¨ssbauer spectroscopic studies of
iron phosphate glasses containing U, Cs, and Bi. J. Non-Cryst. Solids 249, 106–116
(1999).
37. Mo¨ncke, D. & Ehrt, D. Irradiation induced defects in glasses resulting in the
photoionization of polyvalent dopants. Opt. Mater. 25, 425–437 (2004).
38. Paul, A. Chemistry of Glasses Ch.7 (Colored glasses), 204–276 (Chapman and
Hall Ltd, London, United Kingdom; New York, U.S.A., 1982).
39. Stuart, B. C., Feit, M. D., Rubenchik, A. M., Shore, B. W. & Perry, M. D. Laserinduced damage in dielectrics with nanosecond to subpicosecond pulses. Phys.
Rev. Lett. 74, 2248 (1995).
40. English, R. E., Miller, J., Laumann, C. & Seppala, L. ICF Annual Report 1997
(UCRL-LR-105821-97) from LLNL ICF Annual Report, Jason, C. and Don, C.
(ed.), 112–131 (ICF International Inc. CA, 1997).
41. Mo¨ncke, D. & Ehrt, D. Materials Science Research Horizons: Photonization of
polyvalent ions, Editor: Hans P. Glick Ch. 1. (Nova Science Publishers, Inc. New
York, USA. 2007).
42. Bloembergen, N. Role of cracks pores and absorbing inclusions on laser induced
damage threshold at the surface of transparent dielectrics. Appl. Opt. 12, 661–664
(1973).
43. Suratwala, T. I. HF-Based etching processes for improving laser damage resistance
of fused silica optical surfaces. J. Am. Ceram. Soc. 94, 416–428 (2011).
44. ISO11254-1:2000(E), Laser and laser-related equipment—Determination of laser[induced damage threshold of optical surfaces–Part 1: 1-on-1 test. http://www.iso.](http://www.iso.org/iso/catalogue_detail.htm?csnumber=43001)
[org/iso/catalogue_detail.htm?csnumber543001.](http://www.iso.org/iso/catalogue_detail.htm?csnumber=43001)
45. Parham, T. G. et al. Large Aperture Optics Performance, LLNL-TR-410955
[(2009), https://e-reports-ext.llnl.gov/pdf/370414.pdf, Date of access: 25/02/2009.](https://e-reports-ext.llnl.gov/pdf/370414.pdf)
46. Hunt, J. T. National Ignition Facility Performance Review 1999, UCRL-ID[138120-99 (2000), https://e-reports-ext.llnl.gov/pdf/240043.pdf, Date of access:](https://e-reports-ext.llnl.gov/pdf/240043.pdf)
30/09/2000.
47. Hou, C. H. et al. Preparation of the oxyfluoride glass with high 3v laser induced
damage threshold. Optics & Laser Tech. 56, 88–91 (2014).

Acknowledgments
The authors acknowledge the financial support by the National Natural Science Foundation
of China (NSFC NO.61307046, NO.61205039 and NO.61177086) and West Light
Foundation of the Chinese Academy of Sciences. We gratefully thank Prof. Doris Ehrt at
Otto-Schott-Institute, Friedrich Schiller University Jena for her stimulating discussions on
the fluorescence phenomenon and reviewing the manuscript. We would like to thank Mr.
Junfeng Xiang at Institute of Chemistry, Chinese Academy of Sciences and Ms. Lajia Yu at
Xiamen University for their help with the NMR and EPR spectra measurement.

Author contributions

B.P. conceived the project; B.P., M.L. and P.F.W. designed the experiments; M.L., P.F.W.,
C.Q.H., F.G. and H.T.G. performed the experiments; P.F.W., Y.T.X. and Z.W.Z. analyzed
the data; P.F.W., Z.W.Z. and B.P. wrote the main manuscript text. All authors reviewed the
manuscript.

Additional information
Competing financial interests: The authors declare no competing financial interests.

How to cite this article: Wang, P.F. et al. Luminescence in the fluoride-containing
phosphate-based glasses: A possible origin of their high resistance to nanosecond pulse
laser induced damage Sci Rep 5 8593; DOI:10 1038/srep08593 (2015)

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