Advances in Glass and Optical Materials, Volume 173

113 Pages·2006·5.325 MB·English

Advances in Glass and
Optical Materials
Advances in Glass and
Optical Materials
Ceramic Transactions Volume 173
Proceedings of the 107th Annual Meeting
of The American Ceramic Society,
Baltimore, Maryland, USA (2005)
Editor
Shibin Jiang
Published by
The American Ceramic Society
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Westerville, Ohio 43081
www.ceramics.org
Advances in Glass and Optical Materials
Copyright 2006. The American Ceramic Society. All rights reserved.
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ISBN 1-57498-243-5
10 09 08 07 06 5 4 3 2 1
IV Advances in Glass and Optical Materials
Contents
Preface vii
Development of Highly Nonlinear Extruded Lead Silicate Holey Fibers with
Novel Dispersive Properties 1
Julie Y.Y. Leong, Periklis Petropoulos, Heike Ebendorff-Heidepriem, Symeon Asimakis,
Roger C. Moore, Ken Frampton, Vittoria Fmazzi, Xian Feng, Jonathan H.V. Price,
Tanya M. Monro, and David J. Richardson
Fabrication of Photonic Crystal Slabs and Microstructures by Electrophoretic
Deposition(EPD) - What are the Fabrication Limits? 11
Johannes Zeiner and Rolf Clasen
Glass Ceramics for Solid State Lighting 19
SetsuhisaTanabe
Electrical and Optical Properties of Phosphate Glasses Containing
Multiple Transition Ions 27
Biprodas Dutta, Niveen A. Fahmy and Ian L. Pegg
Incorporation of Biological Agents in Random Hole Optical Fibers 39
Gary R. Pickrell and Navin J. Manjooran
Bioapplications for Photo-Hydrolyzed Glass Surfaces 47
Rebecca L. DeRosa, Ashleigh Cooper, and Jean A. Cardinale
A Tunable Inorganic Blotting Membrane for Analysis of Gel Separated
Biomolecules by MALDI-MS 59
Mark A. Lewis, Julie E. Fajardo, Robert R. Hancock, Robert S. Burkhalter, and Carrie L. Hogue
Formation of Metallic Copper Clusters in Silica Based Glasses 71
Neva Capra, Luca Pederiva, and Roberto Dal Maschio
In-Situ Observation of Relaxation Process in F-Doped Silica Glass by
Raman Spectroscopy 79
N. Shimodaira, K. Saito, E. H. Sekiya, and A. J. Ikushima
Selective Batching for Improved Commercial Glass Melting 87
Ungsoo Kim, Eric J. Nichols, William M. Carty, and Christopher W. Sinton
Glass Fibers Industry: Evolutions of Glass Compositions 95
Alain de Meringo
Patents: Tapping a Valuable Resource 105
Pat LaCourse
Author Index 113
Advances in Glass and Optical Materials v
Preface
This proceedings volume is devoted to manuscripts in glass and optical materials, which were presented at the
Glass and Optical Materials Division (GOMD) symposium during the 107th Annual Meeting and Exposition of
The America Ceramic Society, April 10-13,2005, in Baltimore, MD. Twenty invited talks, forty-five con-
tributed talks and thirteen posters were presented in addition to an extremely successful session on developing
and commercializing high-risk technologies.
The well-attended meeting indicates that the research activity in the field of glass and optical materials is still
very active and innovative, although the photonics industry, especially the optical fiber communication indus-
try, is going through a difficult time. As an engineer in photonics industry I am strongly encouraged to see the
high level activity in GOMD community. Hard work is probably the only way to turn the situation around
because great innovation and successful commercialization will result in a blooming industry.
This volume reflects the current research and development status of glass and optical material. A few of them
are highlighted here. Exceptional progresses have been made in micro-structured fibers and photonic crystal
fibers, which provide unique optical and photonic properties that are not obtainable previously. Many scientists
believe that the benefit of micro-structured materials, especially in photonics area, will go beyond our imagina-
tion. Glass ceramics for solid-state lighting illustrates a new way to save our precious energy resource, which is
widely realized as a critical factor for our society in the near future. Glass for bio-applications is emerging as
important subject of research. Three papers in this volume address the development of glass for bio-applica-
tions.
I am honored to have the privilege to serve as program chair of this GOMD meeting. It was a great experience
to interact with the staff at The America Ceramic Society, the GOMD session chairs, the invited speakers, and
contributed authors. Because of my need to travel to Shanghai for the acceptance of the Gottardi Prize from
International Commission on Glass during the meeting, I am especially grateful for the help of the GOMD
organizers for managing such a successful symposium. United together, we can make the GOMD symposium
better each year.
Shibin Jiang
Advances in Glass and Optical Materials vu
Advances in Glass and Optical Materials
Edited by Shibin Jiang
Copyright © 2006. The American Ceramic Society
DEVELOPMENT OF HIGHLY NONLINEAR EXTRUDED LEAD SILICATE HOLEY
FIBERS WITH NOVEL DISPERSIVE PROPERTIES
Julie Y.Y. Leong, Periklis Petropoulos, Heike Ebendorff-Heidepriem*, Symeon Asimakis, Roger
C. Moore, Ken Frampton, Vittoria Finazzi, Xian Feng, Jonathan H.V. Price, Tanya M. Monro*,
David J. Richardson
Optoelectronics Research Centre, University of Southampton, Southampton SO 17 1BJ, UK
[email protected]
ABSTRACT
We describe the development and fabrication of small-core high-NA lead silicate glass
holey fibers. These fibers exhibit the lowest ever losses and highest ever nonlinearities reported
for a HF in this glass. Both theoretical modeling and experimental demonstrations of broadband
supercontinuum generation at 1.06 urn achieved using pulse energies of just -100 pJ confirm
that these fibers have a zero-dispersion wavelength around 1 um.
INTRODUCTION
Holey Fibers (HFs) were first developed in 1996 and have subsequently generated
enormous interest for use in areas as diverse as spectroscopy, metrology, biomedicine, imaging,
telecommunications, industrial machining and the military. Recently, advances in optical fiber
technology have allowed the fabrication of fibers with levels of effective nonlinearity per unit
length (/) that would generally have been deemed practically unrealizable just a few years ago.
Central to this rapid progress have been both the development of glasses with high Kerr
nonlinearity coefficients and good thermal stability, and the development of HF fabrication
technology. The emergence of HF technology is particularly enabling as it allows the fabrication
of extremely small core, high Numerical Aperture (NA) fibers capable of providing far tighter
mode confinement than conventional solid core fibers. Moreover, it allows fibers to be made
from just a single material, eliminating the need for two thermally, chemically and optically
compatible glasses to form the fiber core and cladding as otherwise required. HF technology thus
provides a simple and convenient route to realizing fibers in high nonlinearity glasses that
otherwise might not be able to be drawn into fiber form.
To date, highly nonlinear soft glass HFs have been demonstrated for lead silicate(1,2),
bismuth silicate(3) and tellurite(4) glasses. Recent progress in bismuth-oxide based glasses has
been particularly noteworthy with reports of a bismuth-oxide HF with a /of 1100 W1km",(3), and
a step-index bismuth-oxide glass fiber, made of an even more nonlinear bismuth borate glass,
exhibiting a /value of 1360 W"1 km"1 with a lower loss of ~ldB/m(5). These numbers represent
the current state-of-the-art to the best of our knowledge in terms maximum reported fiber
nonlinearity for both fabrication approaches. Note that, although the step-index bismuth-oxide
glass fiber has demonstrated a very high nonlinearity, the large normal fiber dispersion resulting
from the large normal material dispersion of this material restricts the applicability o fthis fiber.
In contrast, the novel waveguiding properties of HFs offer the possibility of overcoming the
large normal material dispersion of high-index glasses. Indeed, soft glass HFs with near-zero or
anomalous dispersion at 1550 nm have been demonstrated(M).
Here we report on our recent progress on the development o fHFs with high nonlinearity
and shifted dispersion characteristics using lead silicate glass SF57 from Schott Glass Co.
Advances in Glass and Optical Mater 1
Among the high-nonlinearity soft glasses, lead silicate glass has proven to be particularly
promising for high-nonlinearity HFs(1"2). Previously, we reported a lead-silicate (Schott SF57
glass) HF with y=640 W"!km"1( \ By improving our fabrication process, and optimizing our fiber
design, a value of 7=1860 W^km"1 at 1.55 urn and at the same time improved fiber losses have
been achieved. This y value approaches the ultimate limit for this material and represents the
highest value of nonlinearity yet reported for an optical fiber. In addition we show, that through a
slight modification in our design, we can tune the dispersion characteristics of the fiber to
improve its performance for supercontinuum generation when pumped at wavelengths around
1.06 urn. This wavelength region is technologically significant in that it can be readily addressed
using Yb-doped fiber lasers to realize fully fiberized supercontinuum sources.
FABRICATION AND FIBER STUCTURE
Lead silicate glasses are excellent materials for highly nonlinear HFs due to their suitable
combination of properties. Lead silicate glasses offer higher thermal and crystallization stability
and less steep viscosity-temperature-curves, although their material nonlinearity is lower than in
chalcogenide and heavy metal oxide glasses(6). They also exhibit low softening temperatures of
~500°C(7), which allow the utilization of extrusion for fiber preform processing. Schott SF57
glass exhibits the highest nonlinearity among the commercially available lead silicate glasses.
The high lead concentration of this glass leads to the high linear refractive index of 1.81 at
1550nm with losses in the bulk glass as low as 0.3dB/m at 1550nm(8). The nonlinear refractive
index has been measured to be 4.1xl0"19 m2/W at 1060nm(8). This glass is a promising candidate
for the fabrication of high nonlinearity small core HFs and we used it in our experiments.
We used a three-step procedure for the production of our first fibers (Fig.l). A block of
cylindrical shaped glass of outer diameter (OD) =30mm and height=30mm is cut out from a
block of SF57 bulk glass by ultrasonic drilling. Firstly, the structured preform and the jacketing
tube are to be extruded. Secondly, the structured preform, which has an OD of ~16mm, is
annealed and then drawn on a fiber drawing tower into a smaller scale fiber called cane of about
lmm OD. The jacketing tube is extruded with OD of 10mm and inner diameter (ID) of about
-lmm (preferably the same as the cane size). Finally, the annealed cane is inserted within the
extruded jacketing tube and the assembly is again drawn down to an end fiber. Extrusion is
possible for this glass because of its low melting temperature, and excellent thermal stability
characteristics. Microstructured preforms, rod and tubes fabricated in this way are reproducible
and good dimensional control can be achieved. The feasibility of this approach for very small
core high NA HFs fabrication has been proven in the ORC ^t9\ Careful adjustment of the
tension applied during fiber drawing allowed us to accurately control the outer diameter of the
fiber, and hence the dimensions of the inner core itself. HFs with core diameter in the range of
1.0-1.3 um were produced from 2 different assemblies. From a single preform of length of
-15 cm, we produced fiber lengths of ~200 m, wound on a spool in several bands of uniform
outer diameter in the range 100 to 150 urn. Note that, the ratio between core size and fiber
diameter can be changed via the choice of jacketing geometry and corresponding cane size,
which allow the fiber diameter for a certain core size to be set to the desired value.
We produced small-core high-NA HFs, where the core is optically isolated from the outer
glass region by three fine struts, which ensures maximum index contrast between the core and
cladding regions and allows the formation of extremely small cores (1.0 - 1.4 urn in this case)
with low confinement loss (estimated < lO^dB/m). A typical Scanning Electron Microscopy
(SEM) image of the resulting fiber cross-section is shown in Fig.2. All the HFs demonstrate
2 Advances in Glass and Optical Materie
similar transverse index profiles. The three fine struts that join the core to the outer section of the
fiber have the length in the range of 3-5 urn (depending on the core size and the hole shapes) and
thickness of <250 nm.
EXTREMELY HIGH NONLINEARITY FIBER
We first performed a range of design calculations for a triangular core, SF57 HF structure
(see Fig.2) in order to establish the variation in effective nonlinearity with core diameter of the
HFs. The calculations were performed using FEMLAB, a commercial full-vector modal solver,
based on the Finite Element Method (FEM). The results of these calculations are summarized in
Fig.3 where we plot y versus core diameter for both operating wavelengths of 1550 nm and
1060 nm. From this plot, we determined that a HF with a value of y approaching 2000 W^km"1 at
1550 nm is possible for core diameters in the range 0.6-1.0 urn. This fiber type is interesting for
several nonlinear applications, offering the prospect for the realization of compact nonlinear
devices operating at low powers. Our smallest core fiber with a core diameter of 1 urn (Fiber#l)
is close to the peak of the nonlinearity curve that corresponds to 1.55 um in Fig.3. Note that, we
targeted a diameter of 1 um as this provides a reasonable trade-off in terms of nonlinearity and
ease and efficiency of coupling into the fiber.
We first determined the guidance characteristics of Fiber#l at both 1 urn and 1.55 urn,
both experimentally by imaging the near-field of the guiding mode with an infrared camera and
theoretically by calculating the mode profile from the SEM image. For both wavelengths, the
predicted fundamental mode profile has a triangular shape (Fig. 4a, b), in good agreement with
the measured mode profile (Fig. 4c). The predicted effective mode areas are 0.84 um2 at 1.06 um
and 1.1 urn2 at 1.55 urn. A white light loss measurement was performed which snowed a loss of
2.1 dB/m at 1.06 urn and 2.3 dB/m at 1.55 urn (Fig.5). The reduced losses o tfhis HF represent a
gradual improvement from our earlier demonstrations (~9dB/m(1)), which we attribute to
advances in the fabrication through the use of ultrasonic cleaning of the preform. To explore the
impact of the microstructure on the fiber properties, we also produced unstructured and unclad
fibers (so-called bare fibers), which were drawn directly from extruded rods. For this heavily
multimode solid SF57 fiber, we measured a loss of 1.0 dB/m at 1 um (Fig.5) indicating a modest
increase in the background loss in going from bulk glass to fiber.
The effective mode area Aff and effective nonlinearity y of a fiber at a wavelength A are
e
related via(10)
y = 2nn/(AAeff) (1)
2
where rt2 is the nonlinear refractive index of the glass. The effective nonlinear coefficient, y, of
the small-core HF at 1550nm was estimated from the measurement of the nonlinear phase shift
that was induced through self-phase modulation on a continuous wave, dual frequency, optical
beat signal which propagated through the fiber(9). The results of this measurement are
summarized in Fig.6 and yield an estimate of y = 1860 W^km"1, establishing this HF as the most
nonlinear fiber ever produced. This number is slightly higher than our predicted value and we
estimate it to be within 10-20% of the maximum value possible in this glass.
DISPERSION MANAGEMENT AND OPTIMIZED SUPERCONTINUUM GENERATION
AT 1.06uM
In order to assess the dependence of the fiber dispersion characteristics on the core
diameter of the HFs, the group velocity dispersion of a range of HFs of various core dimensions
was calculated from the index profile of the fibers using FEM-based calculations. The zero-
Advances in Glass and Optical Materü 3
dispersion wavelength for this glass is -1.97 urn, however the strong waveguiding properties of
the HF allow to overcome the large normal material dispersion at short wavelengths. For a given
wavelength, the dispersion value of small-core HFs increases with a decreasing core size due to
enhanced waveguide dispersion. As a result, the zero-dispersion wavelength is shifted towards
shorter wavelengths. The results of our calculations are summarized in Fig.7 where we plot the
corresponding dispersion curves for different core diameters. The plots show that a fiber with a
zero-dispersion wavelength at 1060 nm (and also exhibiting a y = -2000 W"1 km"1 at these
wavelengths) is possible for a core diameter of 1.3 urn. This HF exhibiting an extremely small
solid glass core and a very high air-filling fraction, not only displays unusual chromatic
dispersion properties but also yields very high optical intensities per unit power. Thus it can be
extremely well suited for nonlinear optic applications, where high effective nonlinearities,
together with excellent control of chromatic dispersion, are essential for power-efficient devices.
During the pull described in the previous section, we also fabricated a fiber with a slightly larger
core (1.3 urn - Fiber#2), in accordance to these specifications. This fiber had similar properties
in terms of mode shape and loss to Fiber#l.
At present we have no ready way to measure the dispersion profile of short lengths of our
fibers around 1 urn, so we chose to directly perform spectral broadening/supercontinuum
experiments to highlight the fact that these HFs have a low dispersion in the 1 urn range. We
launched 200 fs pulses at a repetition rate of 80 MHz and a wavelength of 1.06 um with pulse
energies up to 200pJ into short lengths of the two fibers. The pulses were first launched into
-3 m of the 1.0 urn core HF (Fiber#l). Note, this length is far longer than required for the
generation of supercontinuum and that so far we have made no attempt to optimize our set-up in
terms of fiber length. For modest power levels (launched pulse energies below -45 pJ) we saw
clear evidence of Raman soliton formation (Fig.8a). As we increased the power further, the
spectral extent of the newly generated frequencies became broader (extended mainly towards the
longer wavelength side) and the spectrum became smoother. We achieved a spectral broadening
in excess of 600 nm for launched pulse energies as low as 80 pJ. The spectral dip observed
around 1.44 um is due to the OH' absorption in the fiber which peaks at this wavelength (see
Fig.5).
We next experimented with a -50 cm long piece of the 1.3 urn core HF (Fiber#2). The
zero-dispersion wavelength of this HF was much closer to the operating wavelength of the laser.
This is most clearly evidenced by the significant spectral broadening due to SPM and four wave
mixing at both longer and the shorter wavelengths relative to the pump observed at reduced pulse
energy levels (see the 8 pJ plot in Fig.8b). No such broadening is observed for Fiber#l (see the
14 pJ plot in Fig.8a). At higher pulse energies (100 - 130 pJ) the spectral components in Fiber#2
spanned more than an octave and extended well into the snorter wavelength IR/visible regions of
the spectrum.
CONCLUSION
We have produced small-core lead silicate HFs of extremely high effective nonlinearity
coefficient with the value of /= 1860 W^km'1, which we believe it is the highest value achieved
in a fiber to date. The value of /= 1860 W^km"1 that we have measured for a 1.0 urn core HF at
a wavelength of 1.55 urn approaches the maximum that can be achieved in this glass. We have
used this HF, and another modified design offering improved dispersion characteristics, for
supercontinuum generation at 1.06 urn. Using just -100 pJ energy pulses we observed a
bandwidth of -600 nm (for Fiber#l) and an even broader bandwidth (>750nm) for Fiber#2.
4 Advances in Glass and Optical Materie
These results demonstrate that lead silicate HF are indeed promising fibers for the development
of compact nonlinear devices operating at low powers and offering appropriate dispersion.
Application of the same fabrication approach to other more nonlinear glass materials than SF57
should ultimately allow for fibers with even higher values of effective nonlinearity per unit
length.
ACKNOWLEDGEMENTS
J.Y.Y. Leong is supported by a Malaysian Government Studentship. S. Asimakis is supported by
the Greek State Scholarships Foundation.
* The current address of H. Ebendorff-Heidepriem and T.M. Monro is School of Chemistry and
Physics, University of Adelaide, Australia.
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Advances in Glass and Optical Materials 5