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This PDF file contains the front matter associated with SPIE Proceedings Volume 8249, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.
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Multiphoton absorption polymerization (MAP) is a powerful photolithographic technique that is capable of producing
complex, three-dimensional structures. One key to improving the resolution of MAP is to employ photoinitiators that
can be photodeactivated. This approach is known as resolution augmentation through photo-induced deactivation
(RAPID). To enhance the efficiency and resolution of RAPID, it is necessary to develop a deeper understanding of the
photochemistry of the molecules used to initiate polymerization. To study the nature of the active intermediate species
capable of self-deactivation, here we present experiments in which the exposure and the timing of excitation and
deactivation are varied for photopolymerization reactions occurring at a single location within a photoresist as well as
experiments in which the dependence of feature size on fabrication velocity is determined.
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Progress in materials for radical initiated, radical inhibited super-resolution lithography is reported. The photochemistry
and optical system is described, with a brief discussion on the theory of operation. A motivation
is presented for developing a new material that may be used as a spinnable photoresist, and qualitative resist
requirements are discussed. Results from FTIR experiments suggest how viscosity and monomer type may affect
resist performance. Finally, focused beam photoinhibition experiments on a novel photoresist are presented.
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We describe synthesis of a new super-dense phase of aluminum under extreme pressure and temperature conditions
created by laser-induced microexplosions in sapphire. Micro explosions in sub-micrometer sized regions
of sapphire were induced by tightly-focused femtosecond laser pulses with a temporal length of ~ 100 fs and
an energy of ~ 100 nJ. Fast, explosive expansion of photogenerated high-density plasma created strong heating
and pressure transients with peak temperature and pressure of ~ 105 K and 10 TPa, respectively. Partial
decomposition of sapphire in the shock-compressed sapphire led to formation of nanocrystalline bcc-Al phase,
which is different from ambient fcc-Al phase, and was permanently preserved by fast quenching. The existence
of super-dense bcc-Al phase was confirmed using X-ray diffraction technique. This is the first observation of
bcc-Al phase, which so far has been only predicted theoretically, and a demonstration that laser-induced micro
explosions technique enables simple, safe and cost-efficient access to extreme pressures and temperatures
without the tediousness typical to traditional techniques that use diamond anvil cells, gas guns, explosives, or
megajoule-class lasers.
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The Femtosecond laser micromachining is a versatile tool for fabrication of microfluidic channel network; we exploit the
fast prototyping capability of this technology to produce various channel configurations and study the alignment and
topological defects in microchannels filled with Liquid crystals. The configurations consist of multiple intersections of
microchannels to form networks both in 2D and 3D. The effect of each configuration on the defect formations is also
studied.
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Resonant subwavelength gratings have been designed and fabricated as wavelength-specific reflectors for application as
a rotary position encoder utilizing ebeam based photolithography. The first grating design used a two-dimensional
layout to provide polarization insensitivity with separate layers for the grating and waveguide. The resulting devices had
excellent pattern fidelity and the resonance peaks and widths closely matched the expected results. Unfortunately, the
gratings were particularly angle sensitive and etch depth errors led to shifts in the center wavelength of the resonances.
A second design iteration resulted in a double grating period to reduce the angle sensitivity as well as different materials
and geometry; the grating and waveguide being the same layer. The inclusion of etch stop layers provided more accurate
etch depths; however, the tolerance to changes in the grating duty cycle was much tighter. Results from these devices
show the effects of small errors in the pattern fidelity. The fabrication process flows for both iterations of devices will be
reviewed as well as the performance of the fabricated devices. A discussion of the relative merits of the various design
choices provides insight into the importance of fabrication considerations during the design stage.
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An efficient monolithic fabrication technique of multiple Guided-Mode Resonance Filter (GMRF) devices on a single
substrate is presented. The devices consist of two crossed linear sub-wavelength grating (SWG) dielectric layers, formed
by etching deposited silicon oxide films, separated by a silicon nitride waveguide. The buried SWG duty cycle is
lithographically modulated to control the device resonance wavelengths, independent of the top SWG. This is because
the buried SWG acts as a tunable effective index layer, controlling the waveguide mode coupling wavelength into the
silicon nitride waveguide layer. The two SWG have different spatial periods, to further reduce resonance coupling
between them. The fabrication is accomplished using existing photolithographic technology, and conventional PECVD
coating techniques.
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We design and fabricate arrays of diffractive optical elements (DOEs) to realize neutral atom micro-traps for
quantum computing. We initialize a single atom at each site of an array of optical tweezer traps for a customized
spatial configuration. Each optical trapping volume is tailored to ensure only one or zero trapped atoms.
Specifically designed DOEs can define an arbitrary optical trap array for initialization and improve collection
efficiency in readout by introducing high-numerical aperture, low-profile optical elements into the vacuum
environment.
We will discuss design and fabrication details of ultra-fast collection DOEs integrated monolithically and coaxially
with tailored DOEs that establish an optical array of micro-traps through far-field propagation. DOEs, as mode
converters, modify the lateral field at the front focal plane of an optical assembly and transform it to the desired field
pattern at the back focal plane of the optical assembly. We manipulate the light employing coherent or incoherent
addition with judicious placement of phase and amplitude at the lens plane. This is realized through a series of
patterning, etching, and depositing material on the lens substrate. The trap diameter, when this far-field propagation
approach is employed, goes as 2.44λF/#, where the F/# is the focal length divided by the diameter of the lens
aperture. The 8-level collection lens elements in this presentation are, to our knowledge, the fastest diffractive
elements realized; ranging from F/1 down to F/0.025.
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This paper presents a narrow spectral filter based on a monolithic material system. Guided-mode resonance is
achieved by embedding a periodic array of air holes within a similar-index material. Microvoids created in the lowindex
substrate during deposition of the waveguide give a relatively high index contrast for guided-mode resonance.
One and two-dimensional gratings are used to examine polarization dependence of the device. Theoretical and
experimental results are provided, demonstrating a roughly six nanometer resonance at the full width half-maximum for
both geometries.
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We investigated an affordable, accurate and large scale production method to fabricate sub-wavelength grating structures
by replication in polycarbonate substrates by hot embossing. We used hydrogen silsesquioxane (HSQ) a high resolution,
binary, inorganic, negative electron beam resist, on silicon substrate to make a stamp for replication. We fabricated the
stamp on silicon by using HSQ-resist without any etching process with simple process steps. The process starts by
depositing an HSQ-resist layer on a silicon substrate and by a measurement of the desired film thickness by adjusting the
spinning speed and time. The resist material is then subjected to e-beam writing followed by a heat treatment to enhance
the hardness and to reveal properties analogous to solid SiO2 as a hot embossing stamp material. A comparison study is
made with and without the etching process with different etching rates. We demonstrate that an effective and inexpensive
stamp for thermal nano-imprint lithography (NIL) for optical gratings is provided without an etching process, which
gives a uniform imprinting density over the entire grating surface and high imprint fidelity. The reflectance spectra of
replicated grating structures are also shown to be in agreement with theoretical calculations.
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In this paper, we will present the concept, fabrication methods, and simulation results of a novel type of Graded
Transmissivity Optic based on a space variant Guided Mode Resonance Filter (GMRF). This GMRF comprised of a
single dielectric layer deposited on a transparent substrate. The layer is PECVD grown Silicon Nitrirde with a
subwavelength grating (SWG) partially etched through it. The unetched portion of the layer is termed the waveguiding
region. When light is incident upon the GMRF at the resonant wavelength, the SWG couples light into a waveguide
mode. However, due to the SWG on the waveguide, this mode is leaky and re-couples the light back towards the source.
The resonance of the GMRF is a function of the optical properties of the materials used; the thickness of the dielectric
layers; and the period and fill-fraction of the SWG. The resonance will change across the device by slowly varying the
thickness of the waveguiding layer. Previous work has varied the resonance across the structure by varying the fill
fraction of the grating. The methods involved in the previous work made that process usable for only a very narrow
range of wavelengths, however this new method will be scalable to a larger wavelength range. The waveguiding layer
will be sculpted using Additive Lithography and ICP etching. Afterwards the SWG will be patterned into the Silicon
Nitride Layer.
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We report on a combined differential scanning calorimetric (DSC) and Raman scattering study of thermal
polymerization of sol-gel organic-inorganic SZ2080 and SU-8 resists. In SZ2080, endothermic peak at 95°C
signify drying of the resist and justifies the required pre-bake at around 100°C for 1-2 h for the best performance
during femtosecond (fs-)direct laser writing. A strong exothermic peak at 140°C (under 2 K/min heating rate)
completes polymerization of the resist. It is revealed that 1wt% of photoinitiators change Raman scattering
intensity of SZ2080 and can contribute efficiently to heating and cross-linking of photo-polymers. In the case
of SU-8, a 65°C DSC feature related to solvent evaporation was observed. The strongest changes in Raman
spectrum occurs at a narrow 895 cm-1 band which is linked to polymerization. Raman scattering taken during
DSC revealed spectral changes following the polymerization; an applicability of this method for monitoring photopolymerization
induced by ultra-fast laser sources and feasibility of a laser-modulated calorimetry is discussed.
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Three-dimensional (3D) microstructures are fabricated by prism-assisted inclined ultraviolet (UV) lithography. The
exposure angles of slanted structures ranging from 0° to 65° in SU-8 photoresist can be easily achieved without
immersion in index matching liquid. The sample surface reflection of UV light can be utilized for the fabrication of
symmetric structures. Tripod structures have been fabricated by one-step UV exposure with corner prism. Examples
of various achievable 3D microstructures are presented.
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We outline recent research into the application of adaptive optical techniques to the laser fabrication of threedimensional
structures with sub-micrometer precision. Aberration correction can be implemented using deformable
mirrors or liquid crystal spatial light modulators (LCSLMs). The correction ensures that the quality
of the laser focus is maintained when focussing at depth into a material with high refractive index. Flexible
parallel fabrication methods have been implemented using a LCSLM through both holographic beam shaping
and an addressable microlens array. Applications have been shown in a range of high index materials, including
diamond, lithium niobate and glasses.
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Extremely short near infrared laser pulses (e.g. 10 fs) offer the possibility of precise sub-100nm processing without
collateral side effects. Furthermore, the can be employed to excite a variety of absorbers simultaneously due to their
broad 100 nm emission band. We demonstrate two-photon fluorescence imaging of green and red fluorescent proteins in
living cells as well as two-photon nanolithography with 12 fs laser pulses (750-850 nm) at low microwatt mean power
using an 85 MHz laser resonator. At a minimum of 400 μW mean power, direct nanoprocessing in blood cells was
realized. Multiphoton ablation in biological specimens follows a P2/τ relation. We were able to create sub-100nm ripples
in silicon wafers, to cut glass, gold, and polymers as well as to create transient nanoholes in the membranes of living
stem cells and cancer cells for targeted transfection.
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The demand for large area and low cost nanopatterning techniques for optical coatings and photonic devices has
increased at a tremendous rate. At present, it is clear that currently available nanopatterning technologies are unable to
meet the required performance, fabrication-speed, or cost criteria for many applications requiring large area and low cost
nanopatterning. Rolith Inc proposes to use a new nanolithography method - "Rolling mask" lithography - that combines
the best features of photolithography, soft lithography and roll-to-plate printing technologies. We will report on the first
results achieved on a recently built prototype tool and cylindrical mask, which was designed to pattern 300 mm wide
substrate areas.
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We report on the fabrication of an eight-channel single-mode waveguide array via vacuum assisted microfluidic soft
lithographic technique. The incorporation of sectional flow tapers perpendicular to the waveguide direction allows
for the realization of long single-mode channel waveguide arrays, thus overcoming the waveguide length limitation
set by the viscosity of the UV curable resin. The refractive index and other properties of the synthesized UV curable
core waveguide resin can be tuned through the reformulation of material composition.
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A novel technique for the fabrication of high resolution sub-micrometer patterns by diffractive proximity lithography in a
mask-aligner is presented. The technique is based on the use of specially designed diffractive photo-masks. It requires
some small modifications of the mask-aligner, especially for the mask illumination and the settings of the proximity gap
between mask and substrate. The huge potential of this novel technique is demonstrated at the example of structures
having lateral feature sizes in the sub-500nm range printed with mask-to-substrate distances of several ten micrometers.
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One and two dimensional grating structures with submicron period have a huge number of applications in optics and
photonics. Such structures are conventionally fabricated using interference or e-beam lithography. However, both
technologies have significant drawbacks. Interference lithography is limited to rather simple geometries and the
sequential writing scheme of e-beam lithography leads to time consuming exposures for each grating. We present a novel
fabrication technique for this class of microstructures which is based on proximity lithography in a mask aligner. The
technology is capable to pattern a complete wafer within less than one minute of exposure time and offers thereby high
lateral resolution and a reliable process. Our advancements compared to standard mask aligner lithography are twofold:
First of all, we are using periodic binary phase masks instead of chromium masks to generate an aerial image of high
resolution and exceptional light efficiency at certain distances behind the mask. Second, a special mask aligner
illumination set-up is employed which allows to precisely control the incidence angles of the exposure light. This degree
of freedom allows both, to shape the aerial image (e. g. transformation of a periodic spot pattern into a chessboard
pattern) and to increase its depth of focus considerably. That way, our technology enables the fabrication of high quality
gratings with arbitrary geometry in a fast and stable wafer scale process.
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Optical surface structuration is of primary interest for applications such as photovoltaics or photodetectors.
Over last years, periodical patterns allowing antireflective effects with efficient properties have been designed
and fabricated. Some specific issues such as diffraction of undesired high energy orders are a direct consequence
of the periodical nature of this kind of pattern.
Random rough surfaces allow the antireflective effect without these undesired diffraction effects. By tuning
their statistics, random rough surfaces offer new degrees of freedom for antireflection but also for controlling
the scattering (polarization, spatial distribution). The two main parameters of such surfaces are the height
probability density function and the autocorrelation function. The height probability density function carries
information about height of the structures. The autocorrelation function is a representation of the lateral
distribution of the surface.
Our photofabrication method uses a speckle pattern recorded on a photoresist. By controlling the exposure
parameters, such as the number of exposure and the beam intensity distribution, one is able to control the
statistics of the speckle, and so of the photofabricated surfaces. Using a chromatic confocal sensor, height
mapping of these surfaces are performed. From these mappings, the height probability density and the
correlation function are calculated.
The experimental statistics are compared with the predicted theoretical ones showing a good agreement.
Results are presented showing a significant modification of the statistics of the photofabricated surfaces.
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Miniaturized optical systems like endoscopy or cell phone lenses systems comprise several optical elements like lenses,
doublets and plane optics. To receive a good imaging quality the distances and angles between the different optical
elements have to be as accurate as possible. In the first step we will describe how the distances and angles between
different elements can be monitored and finally we will describe a technique to actively align small optics (diameter
approx. 1mm and smaller) with respect to each other. For the measurement electronic autocollimators combined with
white-light-interferometers are used. The electronic autocollimator reveals the exact centration errors between optical
elements and the low coherence interferometer reveals the distances between surfaces. The accuracy of the centration
error measurement is in the range of 0.1μm and the accuracy of the distance measurement is 1μm. Both methods can be
applied to assembled multi-element optics. That means geometrical positions of all single surfaces of the final optical
system can be analysed without loss of information. Both measurement techniques complement one another.
Once the exact x,y,z - Position of each optical surface and element is known computer controlled actuators will be used
to improve the alignment of the optics. For this purpose we use piezo-electric-actuators. This method had been applied
to cement e.g. doublets for endoscope optics. In this case the optical axis of one lens has been aligned with respect to the
optical axis of a second reference lens. Traditional techniques usually rely on an uncertain mechanical reference.
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Photonic crystals (PC) can fundamentally alter the emission behavior of light sources by suitably modifying the
electromagnetic environment around them. Strong modulation of the photonic density of states especially by full three-dimensional
(3D) bandgap PCs, enables one to completely suppress emission in undesired wavelengths and directions
while enhancing desired emission. This property of 3DPC to control spontaneous emission, opens up new regimes of
light-matter interaction in particular, energy efficient and high brightness visible lighting. Therefore a 3DPC composed
entirely of gallinum nitride (GaN), a key material used in visible light emitting diodes can dramatically impact solid state
lighting. The following work demonstrates an all GaN logpile 3DPC with bandgap in the visible fabricated by a template
directed epitaxial growth.
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In this paper we present a 45-degree mirror created for optical applications utilizing CMOS high-volume manufacturing
processes with a gray-scale lithography technique. The process that is presented here was done by creating a 3D pattern
in the photoresist and then by transferring the photoresist profile to the Si/SiO2 substrate by specific dry etch processing.
We discuss the optimization of the half-tone pattern to achieve the desired resist profile. We achieved smooth sidewalls
with various sidewall angles and show that different 3D angles and profiles can be achieved and processed
simultaneously.
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We present an immersion hybrid optics specially designed for focusing ultrashort laser pulses into a polymer
for direct laser writing via two-photon polymerization. The hybrid optics enables well corrected focusing over a
working distance range of 577 μm with a numerical aperture (NA) of 1.33 thereby causing low internal dispersion.
We combine the concepts of an aplanatic solid immersion lens (ASIL) for achieving a high NA with the correction
of aberrations with a diffractive optical element (DOE). To demonstrate the improvements for volume structuring
of the polymer, we compare achievable feature sizes of structures written with our optics and a commercial
available oil immersion objective (100x, NA=1.4).
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In this paper, we proposed a tapered hollow tube which can produce a near diffraction-limit spot and focus the incident
light in far-field region. From previous researches, the sub-wavelength annular aperture (SAA) made on metallic film
generates a Bessel beam in far-field region. Also, the traditional tapered fiber has been widely used in near-field
scanning optical microscope (NSOM) to achieve super-resolution in near-field. Combining these two concepts, tapered
hollow tube was shown to have great potential in creating a small sub-micron spot size and long depth of focus (DOF)
emitted light beam. By using the commercially available capillary and fiber heat-pulling method, it was found that tube
processed per design to be disclosed in this paper can achieve Bessel beam as well. It will be shown that the SAA-like
structure was actually implemented by the geometry of the tube tip. From FDTD simulation and experiment, the emitted
beam was identified to have more than 10 μm DOF and 250-300 nm focal spot excited by using the 408 nm laser source.
These results not only can help us pursue lithography applied to create through silicon via (TSV) process in far-field
region while maintaining near diffraction-limit spot size. The high throughput and side lobe became a serious problem
when continuous incident light was used. To circumvent this problem, the incident light from was changed from
continuous to pulse type and a suitable lithography experimental system designed by using three-axis displacement
platform was developed. All results will be detailed in this paper.
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The magnetostatic response of a variety of 3D metallic loop traces are studied numerically by evaluating the Biot-
Savart law as a first step in understanding the radiative behavior of such structures. These numerical studies confirm
that the magnetostatic behavior of localized planar and non-planar current distributions are equivalent to magnetic
dipoles in the far field, however the near-field behavior of these traces can be quite different.
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Large arrays of periodic nanostructures are widely used for plasmonic applications, including ultrasensitive
particle sensing, optical nanoantennas, and optical computing; however, current fabrication
processes (e.g., e-beam lithography and nanoimprint lithography) remain time consuming and expensive.
Previously, researchers have utilized double casting methods to effectively fabricate large-scale arrays of
microscale features. Despite significant progress, employing such techniques at the nanoscale has
remained a challenge due to cracking and incomplete transfer of the nanofeatures. To overcome these
issues, here we present a double casting methodology for fabricating large-scale arrays of nanostructures.
We demonstrate this technique by creating large (0.5 cm × 1 cm) arrays of 150 nm nanoholes and 150 nm
nanopillars from one silicon master template with nanopillars. To preclude cracking and incomplete
transfer problems, a hard-PDMS/soft-PDMS (h-PDMS/s-PDMS) composite stamp was used to replicate the
features from: (i) the silicon template, and (ii) the resulting PDMS template. Our double casting technique
can be employed repeatedly to create positive and negative copies of the original silicon template as
desired. By drastically reducing the cost, time, and labor associated with creating separate silicon
templates for large arrays of different nanostructures, this methodology will enable rapid prototyping for
diverse applications in nanotechnological fields.
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Three dimensional metamaterials are fabricated using direct laser writing in SU-8 polymer followed by an electroless
coating process. A method has been developed to allow for selective electroless plating of SU-8 microstructures
with a smooth conformal coating of Ag. The process utilizes radio frequency plasma pretreatment
to modify the SU-8 surface so that Ag ions can nucleate on the surface, leaving the substrate uncoated. An array
of split ring resonators and other 3D microstructures are used to demonstrate how the technique can be applied
to metamaterials applications.
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An Exposure Controlled Projection Lithography (ECPL) process with the ability to fabricate microlenses on
transparent substrates is presented. This process (also referred to as maskless lithography) can be used to
create polymer microlenses on flat or curved substrates without involving hard tooling. Incident radiation,
patterned by a dynamic mask, passes through a transparent substrate to cure photopolymer resin that grows
progressively from the substrate surface. A process planning algorithm which incorporates the effects of
optical aberrations present in the ECPL system and photopolymer's response to irradiation is presented. An
interferometric process monitoring system is also presented which can be used to control the process in real
time. Samples of micro optical elements fabricated on flat and non-planar substrates using the ECPL system
are also presented, which demonstrate the wide range of fabrication capability of our ECPL process.
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Proton beam writing (PBW) is a high-resolution direct write lithographic technique suitable for the fabrication of
micro/nano optical components with smooth vertical sidewalls. In the present work PBW was used to fabricate smooth
micro cavities in negative tone photoresist SU-8 and Rhodamine B doped SU-8. Two different laser cavities based on
whispering gallery mode resonators were fabricated using PBW. The laser cavities in Rhodamine B doped SU-8 resist
were optically pumped with a pulsed frequency doubled Nd: YAG laser, and emits light in the chip plane at 643 nm. The
presented laser cavities showed pump threshold as low as 3 μJ/mm2, which is the lowest threshold reported in planar
cavities fabricated in Rhodamine B dye based polymer laser cavities.
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The formation of an photosensitive device due to the local breakdown in an MOS structure with an impurity
containing oxide layer has been monitored. A stepwise breakdown of the oxide layer resulted in the formation
of a diode like characteristics with further on stable current-voltage characteristics. Under illumination with
white and blue light we found a high photosensitivity of the resulting structure, probably due to the formation
of a local p-n junction due to out-diffusion from the oxide of n-type dopants into the underlying silicon
substrate. Using a blue light LED illumination during the monitoring of the device formation enables the
identification of the moment, when a high ratio between photo- and dark current is obtained.
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This paper discusses the use of ALD thin films as Bragg mirror structure materials in MEMS Fabry-Perot
interferometers in the visible spectral range. Utilizing polyimide sacrificial layer in the FPI fabrication process is also
presented as an alternative method to allow higher temperature (T= 300 °C) ALD FPI processing. ALD Al2O3 and TiO2
thin films grown at T= 110 °C are optically characterized to determine their performance in the UV - visible range
(λ>200nm) and effects of the ALD temperature on the thin film stacks and the FPI process is discussed. Optically
simulated 5-layer Bragg mirror stacks consisting of ALD Al2O3 and TiO2 for wavelengths between 420 nm and 1000 nm
are presented and corresponding MEMS mirror membrane structures are fabricated at T= 110 °C and tested for their
release yield properties. As a result, the applicable wavelength range of the low-temperature ALD FPI technology can be
defined.
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We present the fabrication and optical characterization of nano-scale solid immersion lenses (nano-SILs) with sizes
down to a subwavelength range. Submicron-scale cylinders fabricated by electron-beam lithography (EBL) are thermally
reflowed to form a spherical shape. Subsequent soft lithography leads to nano-SILs on transparent substrates, i.e. glass,
for optical characterization with visible light. The optical characterization is performed using a high-resolution
interference microscope (HRIM) with illumination at 642 nm wavelength. The measurements of the 3D amplitude and
phase fields provide information on the spot size and the peak intensity. In particular, the phase measurement is a more
convincing proof of the Airy disc size reduction rather than the full-width at half maximum (FWHM) spot size. The focal
spots produced by the nano-SILs show both spot-size reduction and enhanced optical intensity, which are consistent with
the immersion effect. In this way, we experimentally confirm the immersion effect of a subwavelength-size SIL (d = 530
nm and h = 45 nm) with a spot reduction ratio of 1.35, which is less than the expected value of 1.5, most likely due to the
slightly non-ideal shape of the nano-SIL.
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We have developed a direct laser lithography system for fabrication of precision diffractive optical elements such as
Fresnel zone plates and computer-generated holograms. The developed lithography system has possible working area up
to 360 mm and minimum linewidth of 0.5 μm. To assure the performance of the lithography system, the performance
evaluation was carried out on the moving stages, the writing head module, and the light source, respectively. In this
paper, we report the performance evaluation including the standard uncertainties of each part, the combined standard
uncertainty, and finally the expanded uncertainty to give a particular level of confidence.
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Focused femtosecond laser pulses can be used for fabricating photonic devices inside transparent materials. However,
the processing mechanisms are not fully clarified. Previously, we investigated the local and rapid temperature dynamics
of fused silica during femtosecond laser microprocessing by Raman temperature measurement. In this paper, we report
on the energy-dependent temperature dynamics and the spatiotemporal evolution of heat. In the experiment, a
Ti:sapphire laser system generated 80-fs pulses and a frequency-doubled Nd:YAG laser system generated 10-ns pulses.
These pulses were used for microprocessing and Raman excitation, respectively. They were focused into the sample by a
microscope objective. The sample was transferred mechanically during the processing to prevent multiple irradiations.
The temperature at the focus was calculated from the ratio of the intensity of Stokes and anti-Stokes Raman scattering
components of the measured spectrum. The measured temperature near the focal point decreased with different delays
depending on the pulse energy. The spatial distribution of the temperature showed heat diffusion and temperature
decrease. The measured temperature fitted well with the thermal diffusion model. In this way, energy-dependence of
temperature dynamics and spatiotemporal evolution of heat were successfully investigated by using the present system.
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Poly(styrene-b-2-vinyl pyridine) (PS-b-P2VP) lamellar film which is hydrophobic block hydrophilic polyelectrolyte
block polymer of 52 kg/mol -b- 57 kg/mol and PS-b-P2VP film with reactive monomer (RM257) were prepared for
photonic gel films. The lamellar stacks, which is alternating layer of hydrophilic and hydrophobic part of PS-b-P2VP.
We reported about the influence of reactive monomer on those photonic gel films. Added reactive monomer photonic gel
film had higher absorbance than pure photonic gel films. And band gaps of the lamellar films shifted by the time of UV
light irradiation. That Photonic gel films were measured with the UV spectrophotometer. As a result the photonic gel
film with reactive monomer had more clear color. The lamellar films were swollen by DI water, Ethyl alcohol (aq) and
calcium carbonate solution. Since the domain spacing of dried photonic gel films were not showing any color in visible
wavelength. The band gap of the lamellar films were drastically shifted to longer wavelength swollen by calcium
carbonate solution (absorbance peak 565nm→617nm). And the lamellar films were shifted to shorter wave length
swollen by ethanol (absorbance peak 565nm→497nm). So each Photonic gel film showed different color.
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Effects of electric fields on the self-assembly of block copolymers have been investigated for thin films of polystyrene-bpoly(
2-vinyl pyridine); PS-b-P2VP, 52 kg/mol-b-57 kg/mol and 133 kg/mol-b-132 kg/mol. Block copolymers of
polystyrene and poly(2-vinyl pyridine) have been demonstrated to form photonic crystals of 1D lamellar structure with
optical band gaps that correspond to UV-to-visible light. The formation of lamellar structure toward minimum freeenergy
state needs increasing polymer chain mobility, and the self-assembly process is accelerated usually by annealing,
that is exposing the thin film to solvent vapor such as chloroform and dichloromethane. In this study, thin films of block
copolymers were spin-coated on substrates and placed between electrode arrays of various patterns including pin-points,
crossing and parallel lines. As direct or alternating currents were applied to electrode arrays during annealing process, the
final structure of thin films was altered from the typical 1D lamellae in the absence of electric fields. The formation of
lamellar structure was spatially controlled depending on the shape of electrode arrays, and the photonic band gap also
could be modulated by electric field strength. The spatial formation of lamellar structure was examined with simulated
distribution of electrical potentials by finite difference method (FDM). P2VP layers in self-assembled film were
quaternized with methyl iodide vapor, and the remaining lamellar structure was investigated by field emission scanning
electron microscope (FESEM). The result of this work is expected to provide ways of fabricating functional structures
for display devices utilizing photonic crystal array.
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We report the fabrication of silver plasmon-enhanced photodiodes with a single active layer
sandwich mixture, using ITO with Ag nanoparticles and poly (2-methoxy-5-(20-ethylhexyloxy)-
1,4-phenylenevinylene) (MEH-PPV):fullerene-C60 blend. Ag nanoparticles were created first by ebeam
depositing 20 Å of Ag on ITO followed by RTA annealing under nitrogen at 250 °C for 30
min. Devices were fabricated using spin casting the blend over the ITO/Ag nanoparticles. After
baking, Al metal was deposited on top of MEH-PPV fullerene-C60 blend using e-beam evaporation
for the metal contacts. We observed enhanced absorbance due to the Ag nanoparticles and increased
photo response by the fabricated photodetector. I-V characterization allowed us to determine the
barrier height, diode ideality factor, and series resistance. The diode shows a non-ideal I-V behavior
due to a high probability of electron and whole recombination in the depletion region or existence
of tunneling current, or perhaps due to the presence of interfacial layer or series resistance. The
photocurrent and the photoconductive behavior indicate that these devices can be used as solar cells.
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Dynamic maskless holographic lithography (DMHL) is a new micro-manufacturing technique that uses holograms
to create patterns on a substrate instead of a mask. In DMHL, gratings and Fresnel lenses are displayed on
nematic liquid crystal spatial light modulators (SLMs) to steer light to desired locations to expose sensitive
photopolymers. Micro-manufacturing can be done in two modes, serial or parallel. Serial refers to a beam being
scanned through a set of points and parallel refers to an entire intensity pattern being created at once. The
field over which patterning can be performed is affected by the diffraction efficiency of the displayed hologram,
the maximum possible spatial frequency of the SLM, and aliasing (light being steered to unintended spots due
to mismatches between designed and displayed phase patterns). This paper presents a technique to compensate
for these inherent inefficiencies by properly adjusting the amount of time spent by the beam at each point
in the desired feature, the dwell-time, during the lithographic process. The relationship between the spatial
frequency of the appropriate grating or Fresnel lens and the dwell time is discussed. Experiments are presented
with and without this technique applied, and results show that feature uniformity is improved with dwell-time
compensation.
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The roughness on the surface of phase-only micro-optical elements can limit their performance. An optical vortex phase
element was fabricated by using additive lithography with an optimized process to have minimal surface roughness.
Thick photoresist was used in order to obtain the appropriate dynamic range for the desired phase profile. We
investigated the effects of both post applied and post exposure baking processes, as well as the effects of surfactant in the
developer. We found the resist surface roughness to be a function of both the temperature and the time of the respective
bakes, as well as the developer surfactant content.
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