This PDF file contains the front matter associated with SPIE Proceedings Volume 6645, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing

SiN is a promising candidate for the fabrication of photonic crystals (PCs) with band gaps in the wavelength range between 550 nm and 850 nm. Here, we investigate the optical properties of cavities in SiN PC membranes by fluorescence spectroscopy of embedded emitters. For this purpose a dye solution is spin-cast on top of the PC membranes and the fluorescence is studied using a confocal microscopy setup. We observe strong emission resonances of molecules spatially and spectrally coupled to the cavity modes. These resonances are compared to finite-difference time-domain simulations of the PC structures, allowing an optimization of the cavity geometry to achieve high quality factors (several hundreds to nearly one thousand). Furthermore, we study routes to selectively incorporate single emitting particles into the cavities applying scanning probes. In this way we introduce SiN PC cavities as universal tools for the manipulation of the emission properties of a huge variety of different emitters in the visible.

The paper presents our experimental results achieved on the field of investigation of LPCVD silicon nitride based two dimensional photonic crystals for visible wavelengths. Our research concentrates on the photonic band gap and defect engineering with respect to the use of silicon nitride based photonic crystals as optical resonators in the visible range of electromagnetic spectra. In order to optically characterize the fabricated photonic crystals, transmission setup utilizing broad band white light source is being used. Using this setup, photonic band gaps in the range between 500 and 900 nm, and thus covering the entire transmission range of LPCVD silicon nitride in the visible range, could be identified for various values of the slab thickness. By incorporating line defects, we fabricated and investigated several photonic crystal filter demonstrators. By optimizing the defect geometry, we achieved transmission values of over 85%.

To overcome the restriction of the density of optical memory systems due to diffraction limit, we have been studying photonic DNA memory, which utilizes photonic technologies and the DNA computing methodology. Our scheme is on the basis of local DNA reaction using laser irradiation and transportation of DNA using parallel optical tweezers with fabricating DNA clusters by attaching DNA onto beads. This paper reports on a new dynamic optical tweezers system, which combines a spatial light modulator (SLM) and a diffractive optical element (DOE) for manipulating DNA clusters. With this combination, real-time programmable manipulation of DNA clusters is achievable in a large spatial range. We also can choose simple patterns for the SLM, and decrease computation cost. In this experiment, a laser beam (633nm wavelength) illuminates a SLM (Hamamatsu Photonics K. K.; PPM8267), which is imaged on an 80-lp/mm transmission-type grating, then the beam is focused with a water immersible objective lens (x 100, NA 1). Simple blazed-phase patterns have different grating constants that are perpendicular to that of the grating are displayed on the SLM. We succeeded in lifting up three 6-micron-diameter polystyrene beads on a glass slide with light spots duplicated by the grating, then transporting the beads in three dimensions simultaneously with changing the grating constants on the SLM. We demonstrated that a same manipulation was implemented at different positions by duplicating a pattern that was generated when only using the SLM. This is usable in implementing a same operation for different data at multiple positions with a single instruction. The promising applications of the method include a nano-scale image memory with encryption.

Interferometric lithography is one of the techniques used to produce micro and nano-scale periodic patterns like gratings in polymers and other substrates of interest. In this work, holographic surface relief gratings are optically inscribed on spin coated azo-dye (NBD)-labeled phospholipid (phosphatidylcholine) thin films using a low-intensity (10 mW) 244 nm frequency-doubled Ar+ laser. A systematic study of growth and decay of phospholipid grating is reported.

Diatoms are single-celled algae which possess silica shells called "frustules" that contain periodic submicron scale features. A diatom cell culture process was used to fabricate a two-dimensional photonic crystal slab of Ge-doped biosilica that possessed 120 nm holes, 330 nm lattice constant, and dielectric constant of 8.5. This material was integrated into an electroluminescent (EL) device by spin coating of the frustules onto indium tin oxide, followed by atomic layer deposition of 400 nm hafnium silicate. No photonic band gap was predicted. However, the EL spectrum possessed resonant UV line emissions that were consistent with photonic band calculations. An EL band gap between 500-640 nm was also observed between blue and red EL line emissions. These EL characteristics have not been observed previously, and are unique to the diatom photonic crystal. This study represents a first step towards the realization of optoelectronic devices which utilize nanoscale components fabricated through cell culture.

The discovery of tunneling magnetoresistance (TMR) has enhanced the magnetoresistance (MR) ratio from the giant magnetoresistance (GMR) regime of around 10% to over 400% at room temperature. A combination of magnetic tunnel junctions with high magnetoresistance ratio and soft magnetic layers enables the development of ultra-low magnetic field sensor with sensitivity down to the scale of picoTesla. A magnetic field sensor with such high sensitivity would have important applications in biomedicine, information storage, and remote sensing such as higher resolution images for cardiograph and magnetic resonance imaging and thus earlier detection of abnormal health condition; higher hard-disk density; and remote sensing of metallic objects. We have constructed an automated four-probe electrical measurement system for measuring TMR of magnetic tunnel junctions with high throughput, enabling us to optimize the properties of the devices. Magnetron sputtering is used to deposit thin films with thickness ranged from angstroms to nanometers. Photolithography and ion plasma etching are applied to pattern the devices. The devices have a range of size from 10 μm x 10 μm to 80 μm x 80 μm. The device is composed of the bottom electrode, free soft magnetic layer, insulating oxide layer, pinned layer, pinning layer, and top electrode. The magnetization of the free layer can be rotated by the external magnetic field which in turn changes the resistance of the device and provide the sensing capability. The system structure, design consideration, fabrication process, and preliminary experimental results are discussed and presented in this paper.

A platform that enables optical coupling from fiber-ribbon connectors to planar lightwave circuits (PLCs) is described. Flexible optical waveguides are used to form a variable length directional coupler that inserts and extracts light from a waveguide located arbitrarily inside the chip. The contact length can be adjusted for optimal coupling allowing manufacturing variation in materials, widths and cladding thicknesses present on a chip. This approach may be ideal for packaging WDM devices as the 3dB bandwidth of the coupling covers the whole 1300 -1700 nm fiber-optic telecommunication range. Coupling length control in the range of 0.05-0.2 μm leads to maximum coupling in excess of 80% for the range of conditions investigated. Simulations of the performance are discussed and initial fabrication and optical coupling results are presented.

Slot-waveguides have attracted considerable attention recently due to the high-intensity electric fields and power densities that can be achieved in very small volumes of low-index materials. Latest applications of this concept have led to new designs of photodetectors, modulators and CMOS-compatible light-emitting devices. However, the coupling of light to and from fiber optics and slot-waveguides remains a challenge. In this paper we present the numerical analysis of a slotted nanotaper for coupling between a fiber and the horizontal slot-waveguide. We used numerical simulations to study the coupling process and found a minimum mismatch loss of 0.4 dB for a tip width of 105 nm. The mode conversion from the tip of the coupler to the full width of the slot-waveguide was performed with a loss less than 0.2 dB when the length was at least 80 microns. This inverse taper increases significantly the coupling efficiency, compared to other approaches such as direct butt coupling and an improved rectangular silicon nanotaper.

The efficiency of light emitting diode (LED) is limited because large amount of generated light is confined inside of it by total internal reflection. A photonic crystal (PC) layer embedded in LED structure substantially modifies the guiding properties inside the chip and prevents the lateral propagation of light, so that it largely increases the output power of an LED. In this paper, we present both numerical and experiment studies on the enhancement of light extraction of GaN-based light-emitting diodes (LEDs) with hexagonal PC layer. By finite difference time domain (FDTD) simulation, the PC parameters were varied in order to evaluate the enhancement. Best extraction efficiency was obtained with the lattice constant of 400 - 600 nm, the PC thickness of 150 - 200 nm and the ratio of hole radius to lattice constant of 0.3 - 0.4 for the 465 nm LED based on GaN. Furthermore, hexagonal PC GaN-based LED was fabricated using anodic aluminum oxide (AAO) method. The PC layer is located below quantum well active layer and the efficiency was improved more than 20%. It was shown that these numerical results agree reasonably well with the experimental results.

We designed a compact optical resonator with two distributed Bragg reflectors (DBR) embedded on single mode polymer ridge waveguide structure towards micro-scale polymer lasers. Single DBR is made up of alternating layers with λ/4 thickness of air and polymer. Numerical simulation of the device was carried out with 3D FDTD. We investigated the reflectance of single DBR as a function of order and number of periods and found a maximum of 97.8%, achieved for a TE mode with air cladding in material with low refractive index 1.54. Focused ion beam (FIB) lithography was used to open periodic air gaps on a 3 um wide ridge waveguide consisting of 1 um thick polymer layer doped with disperse red 1 (n=1.54) structure. Single DBR with five periods are optically characterized by observing the transmission through the device.

Micro-ring resonators have been traditionally fabricated using expensive III-V materials such as InP or GaAs. Device tuning is typically to utilize the electro-optic effect of the III-V materials that usually leads to complex device layer structures. As another tuning approach, thermo-optic tuning of micro-ring resonators is commonly achieved by heating up the whole chip. In general, it is more challenging to achieve highly localized heating on a common chip for independent tuning of multiple micro-ring resonators residing on the same substrate. To address these issues, we describe the development of wavelength reconfigurable photonic switching using thermally tuned micro-ring resonators fabricated on a low-cost silicon-on-insulator substrate. Independent tuning of multiple micro-ring resonators, spaced at 250 µm, is realized with highly localized micro heaters (50×50 μm² per heater area) fabricated on the same silicon substrate. Owing to the large thermo-optic effect of silicon (Δn/ΔT=1.8×10^-4 K^-1), 8 mA heating current is sufficient to tune a micro-ring resonator with a 3-dB spectral line width of 0.1 nm by 2.5 nm while creating a minor peak shift of less than 0.04 nm for an adjacent resonator. The switching response time is about 1 ms. A 1×4 wavelength reconfigurable photonic switch device has been demonstrated. With a resonator diameter of approximately 10 μm (greater than 18 nm in free spectral range of each micro-ring resonator), larger port-count switch matrix with wavelength reconfiguration on a small device foot print is feasible for the development of large-scale integrated photonics.

Transparent electrically-conductive nanoporous thin films can be used as electrodes to attract dye ions from solution to modulate the reflectance of a surface. Here we demonstrate that this technique can be used to create diffraction gratings that can be modified by the application of a small electrical potential with a selected spatial distribution. Using nanoporous ITO films fabricated by Glancing Angle Deposition, we have produced variable diffraction gratings, fabricated by a variety of methods, including lithography combined with etching techniques or direct patterning using focused ion beam etching. We demonstrate modulation of the diffraction pattern by employing electric force to attract the dye ions into the nanoporous electrode, thereby introducing a substantial local change in the effective refractive index value and thus altering the resultant diffraction pattern and, in some cases, yielding diffractive orders that lie between those associated with the underlying grating. These new orders are easily distinguished and their intensity can be substantially modified by controlling the applied voltage. Because this technique can work with very small pitch gratings, this approach has the potential to enable new applications that may not be readily achieved using conventional liquid crystal technology.

We seek to incorporate enhanced electro-optic (EO) materials into mmW imaging systems. EO based mmW detection systems have demonstrated sub-picowatt noise equivalent power while overcoming many of the drawbacks inherent in other systems including size, cooling, and cost. Current EO imaging systems rely on LiNbO3 modulators because of its strong EO effect. The linear EO effect, which only exists in non-centro-symmetric materials, has been shown to increase by orders of magnitude in quantum confined materials. III-V quantum dot materials offer the potential for a stronger EO effect than LiNbO3 while providing the advantages of III-V semiconductor integration. We focus on MBE grown InAs quantum dots in a GaAs matrix and offer XRD and AFM characterization These quantum dot materials are incorporated into an external Mach-Zehnder Interferometer setup where the Vπ is measured experimentally allowing us to extract an EO coefficient for the InAs/GaAs quantum dot layer of 39.4pm/V, an order of magnitude improvement relative to the bulk coefficients.

We have performed a systematic study of nanoparticle generation using near infrared ultrafast pulsed laser ablation. The materials we have studied include metal, metal alloy, and metal oxide. We find that by optimizing the ablation conditions, as a direct result of ultrafast pulsed laser ablation, polycrystalline and single-crystalline nanoparticles can be abundantly produced without intermediate nucleation and growth processes. Combining with different background gases, versatile structural forms have been obtained for the nanocrystals. Using metal nickel as a sample material, we have produced Ni/NiO core/shell nano-spheres and NiO nano-cubes. In the study of generation of alloy nanoparticles, which has been challenging in fabrication, we demonstrate production of binary alloy NiFe nanoparticles that have the same composition as the target material. Metal alloy nanoparticles containing up to three elements are also produced. For metal oxide nanoparticles, two important oxide materials are studied, including TiO₂ and ZnO. All nanoparticle samples are examined using high resolution transmission electron microscopy for morphological, structural, and chemical analysis. An ion probe is used in situ to study the laser ablation process in real-time.

Magnetic tunnel junctions (MTJs) have received tremendous interest since the discovery of substantial room temperature tunneling magnetoresistance (TMR) due to spin-dependent tunneling, and have been intensively investigated for applications in next-generation memory devices, hard disk drives, and magnetic sensors. In the fabrication of MTJs, etching is needed to remove the top cap layers, upper magnetic layers, and the middle oxide layer in order to form a tunneling junction. In view of this, we have devised an innovative, simple, low-cost endpoint detection method for fabricating MTJs. In this method, the endpoint is detected by measurement of the sheet resistance of the MTJ stack. Only a multimeter is needed in this method, hence it provides a simple low-cost alternative for spintronic device researchers to explore the research field of magnetic tunnel junctions. This technique is also of great use in other kinds of metallic stack etching experiments.

In this paper, we discuss the structural design including the materials, junction areas, and magnetic layers thicknesses, and various noise sources including Johnson noise, shot noise, 1/f noise, and thermal magnetic noise, that must be considered when building a magnetic tunnel junction (MTJ) magnetic field sensor with the goal of SQUID-like sensitivity. Analytical derivations of the sensor sensitivity and different noise sources are provided. A highly-portable software design tool is developed to optimize the various parameters of the sensor design, while also predicting the expected sensitivity, operating frequency range, operating current and power of the finished sensor. The functions and operations of this design tool are described. The relationships between the sensor detectivity and some critical design parameters are studied with this design tool. A possible design for the construction of an ultrasensitive magnetic field sensor is proposed.

This paper (SPIE Paper 66450V) has been retracted by the author and removed from the SPIE Digital Library on 20 October 2009. The original paper was published without the knowledge or consent of other collaborators, for which the author apologizes. As stated in the SPIE Guidelines for Professional Conduct and Publishing Ethics, "SPIE considers it the professional responsibility of all authors to ensure that the authorship of submitted papers properly reflects the contributions and consent of all authors." A serious violation of these Guidelines has occurred, necessitating that the paper be expunged from the conference proceedings.

The principle of interaction of light waves incident on a surface with a subwavelength nanostructure is a key question in the development of solar cells. Efficient thin-film solar cells based on microcrystalline silicon (μc-Si:H) or amorphous silicon (a-Si:H) with an absorber layer in the micrometer range require effective light trapping and an optimal incoupling of the entire sun spectrum. The established approach to achieve this is the application of randomly textured transparent conductive oxides (TCOs). Previous investigations of light trapping in thin-film devices have been conducted with often misleading far field measurements. Optical simulations based on the Finite Integration Technique (CST Microwave Studios) are a valuable approach to analyze the light propagation in thin-film devices and enable the study the subwavelength optics of nano-textured interfaces by solving the Maxwell equations rigorously in 3D. However, the question regarding the optimized lateral feature size, vertical height, resulting interface angle and shape of the texture is essential to reach high energy conversion efficiencies. Various texture designs are studied by numerical modeling. We present a 3D simulation analysis of thin-film silicon solar cell nano-optics that gives clear design criteria to reach high efficiencies.

Chiral sculptured thin films (STFs) of TiO₂ deposited by the serial bi-deposition method can be modified post-deposition to tailor the circular Bragg phenomenon which occurs due to their periodic helical morphology. This post-deposition tailoring is accomplished through annealing and/or wet chemical etching. Annealing of the chiral STF in spectral-hole-filters (SHFs) transforms the material structure from non-crystalline to an anatase structure which is more stable and provides better optical performance. The transformation causes a blue-shift of the circular Bragg phenomenon (CBP) which is quantified and correlated with material properties. Further annealing causes a significant change in morphology, which resembles a "string of pearls", and may be the cause of a loss of transmission. Wet chemical etching is also capable of blue-shifting the Bragg regime of a non-crystalline SHF, while having very little effect on a crystalline SHF. The spectral shift of the Bragg regime is limited by the ability of the nanowires, of which the STFs are composed, to remain attached to the substrate. Wet chemical etching and annealing can be used in combination to allow more control of post-deposition processing.

Silicon based light emitting materials are of particular interest for integrating electric and photonic devices into an all-silicon platform. The progress of nano-scale fabrication has led to the ability to realize silicon emitters based on quantum confinement mechanisms. Quantum confinement in nano-structured silicon overcomes the indirect bandgap present in bulk silicon allowing for radiative emissions. Two common structures that utilize the quantum mechanisms leading to light emission in silicon are nanocrystals embedded in silicon dioxide and silicon/silicon dioxide super lattices. Nanocrystals employ quantum confinement in three dimensions while the super lattice structure induces two-dimensional confinement. Strong photoluminescence (PL) has been demonstrated in both structures, confirming the presence of quantum confinement effects. Our super lattice structures are grown using plasma enhanced chemical vapor deposition (PECVD) with alternating layers of silicon and silicon dioxide. We present here sub-10nm period superlattices confirmed via transmission electron microscopy and x-ray diffraction and reflectivity. We also present a new design for an electrically pumped device along with preliminary current-voltage characteristics.

In this paper, functions of bubble pit that is formed in a recording process of a super-resolution near-field structure (super-RENS) disk are discussed. The result shows that the recorded bubble pit has a greatly influence on both writing and reading for super-RENS disk. The relationship between the bubble pit and readout signal is also investigated.

A composite structure obtained by depositing a Columnar Thin Film (CTF) on a transparent substrate with a periodic array of rectangular grooves of infinite length can function as a narrowband, linear-polarization rejection filter. This device discriminates between the linear-polarization states of an incident plane wave, so that linearpolarization high-quality filters with extremely narrow bandwidths can be designed. Furthermore, the filter response can be tuned by varying the angle of incidence.

Using a scanning near-field optical microscope coupled to a UV laser, an approach we term scanning near-field photolithography (SNP), structures as small as 9 nm (ca. λ/30) may be fabricated in self-assembled monolayers of alkanethiols on gold surfaces. Selective exposure of the adsorbate molecules in the near field leads to photoconversion of the alkylthiolate to a weakly bound alkylsulfonate which may be displaced readily be a contrasting thiol, leading to a chemical pattern, or used as a resist for the selective etching of the underlying metal. A novel ultra-mild etch for gold is reported, and used to etch structures as small as 9 nm. Photopatterning of oligo(ethylene glycol) (OEG) terminated selfassembled monolayers facilitates the fabrication of biomolecular nanostructures. Selective removal of the protein-resistant OEG terminated adsorbates created regions that may be functionalized with a second thiol and derivatized with a biomolecule. Finally, the application of SNP to nanopatterning on oxide surfaces is demonstrated. Selective exposure of monolayers of phosphonic acids adsorbed onto aluminum oxide leads to cleavage of the P-C bond and desorption of the adsorbate molecule. Subsequent etching, using aqueous based, yields structures as small as 100 nm.

We have found that a polymer nano-wire with a radius of around 100 nm has a shear modulus three order of magnitude smaller than that measured from the bulk of the same material. This large difference in shear modulus indicates that elasticity of nano-scale structures is not scalable from bulk material. To understand the elasticity of polymer nano-scale structures, we evaluated influence of fabrication conditions on elasticity of photopolymer nano-wires. We fabricated a nano-wire by two-photon polymerization into a shape of a coil spring: geometry capable to magnify mechanical deformations. We stretched the spring by laser trapping, and from force-strain relation we calculated the shear modulus of the polymer wire. When the laser power for fabrication increased by 20 % from polymerization threshold, the shear modulus increased from 0.39 MPa and saturated at 0.77 MPa. We used Raman spectroscopy to investigate the progress of polymerization reaction for each laser power. From the Raman spectra, the cause of lower shear modulus in the nano-wire fabricated by lower laser power was remarked as inadequate polymerization process. Additional UV irradiation hardened the nano-wire fabricated by lower laser power¹. The result demonstrates that the combinative use of two-photon fabrication and subsequent UV irradiation makes it possible to control both the spatial resolution in two-photon fabrication and elasticity of polymer structures.

We report optical polarizer made of single-wall carbon nanotubes/poly(vinyl alcohol) composite. The film of the composite was mechanically stretched to form uniaxial alignment of carbon nanotubes in the polymer matrix. In order to obtain well-aligned carbon nanotubes efficiently, we used single-wall carbon nanotubes shortened into the length of less than 200 nm. Thanks to π plasmon-originated broad absorption spectrum and strong anisotropy of single-wall carbon nanotubes, the film exhibits the degree of polarization of ~ 95 % with keeping flat transmittance through spectral region from 350 nm to 800 nm. We also observed enhancement of the degree of polarization at the wavelengths of van Hove singularities.

In this paper, we report, for the first time, the effect of the lowered freezing point in a 50% water / 50% antifreeze coolant (PAC) or 50% water / 50% ethylene glycol (EG) solution by the addition of carbon nanotubes and other particles. The experimental results indicated that the nano materials are much more efficient (hundreds fold) in lowering the freezing point than the regular ionic materials (e.g. NaCl). The possible explanation for this interesting phenomenon is the colligative property of fluid and relative small size of nano material. It is quite certain that the carbon nanotubes and metal oxide nano particles could be a wonderful candidate for the nano coolant application because they could not only increase the thermal conductivity, but also efficiently lower the freezing point of traditional coolants.

In this work we report a new carbon nanotubes field emission (CNT-FED) light source with nanocrystalline phosphors. The nanocrystalline powders of cerium doped yttrium aluminum garnet were obtained by modified Pechini method. The phosphor has been electrophoretically deposited on ITO-glass substrates. The cathode composed of carbon nanotubes was fabricated in the same manner. A light source was assembled and tested. Low-voltage cathodoluminescent spectra and I-V characteristics of fabricated cathodes were measured. A possibility of application of Ce doped nanocrystalline YAG phosphor in the field emission displays (FEDs) was discussed.

Self-sensing and actuation were investigated for carbon nanofiber (CNF) and Ni nanowire/polymer composites. Electro-micromechanical techniques can be used for evaluating self-sensing and interfacial properties indirectly under loading/subsequent unloading. Apparent modulus and contact resistivity for CNF/epoxy composites were evaluated as functions of different aspect ratio. CNF/epoxy composites with smaller aspect ratio shown to be higher apparent modulus due to high volume content in case of short aspect ratio. Surface energy via dynamic contact angle measurement was evaluated to obtain interfacial adhesion between nano-materials embedded matrix and carbon fiber sensor. Interfacial properties of CNF/epoxy with different aspect ratios were also obtained indirectly. CNF-PVDF, Ni nanowire-CNF-silicone and Ni nanowire-cellulose actuator were made successfully. Electrochemical actuator of CNF-PVDF was responded in electrolyte solution. Magnetic actuators of Ni nanowire-CNF-silicone and Ni nanowire-cellulose composites were monitored under electro-magnetic field with different frequency, wave function and voltage. Ni nanowire-CNF-silicone actuator with lightness and Ni nanowire-cellulose actuator with rapid frequency response having meaningful merits can be applied for various new smart structural materials.

Optofluidic dye lasers have recently attracted much interest as potentially efficient light sources for integration on lab-on-a-chip micro-systems. However, dye bleaching resulting in limited life-time could limit the applications of such devices in lab-on-a-chip technology. Typically, the problem of dye bleaching is addressed by employing a continuous convective flow of liquid-dissolved dye molecules, compensating the bleaching caused by the external optical pump. In previously reported optofluidic light sources the required convective dye replenishing flow has been achieved by external fluid handling apparatus (syringe pumps), on-chip microfluidic pumps, or by means of capillary effect. We have investigated the bleaching dynamics that occur in optofluidic light sources where a liquid laser dye in a micro-fluidic channel is locally bleached due to optical pumping. A simple one-dimensional diffusion model is used to explore the characteristic evolution of the local un-bleached dye concentration in the optically pumped or bleached volume of the device. In the absence of convective flow, the decay of the local dye concentration in the optically pumped volume is governed by the diffusion rate and the resulting lifetime of the device is mainly limited by the capacity of the fluidic reservoirs. Generic microfluidic platforms typically allow for device layouts with a large volume ratio between the fluidic reservoir and the region being optically pumped. These conclusions drawn from the simple model are supported by basic experiments. Our investigations reveal the possibility that such optofluidic dye laser devices may potentially be operated for days by diffusion without the need for a convective flow. Relying on diffusion rather than convection to generate the necessary dye replenishment significantly simplifies optofluidic dye laser device layouts, omitting the need for cumbersome and costly external fluidic handling or on-chip microfluidic pumping devices.

Holographic lithography is one of the promising techniques that can create three-dimensional (3D) periodic nanostructures without extensive lithography and etching steps. This proceeding discusses novel hybrid lithographic methods based on the holographic lithography in conjunction with photolithography to generate hierarchically-patterned structures. Using various types of photoresists including positive, negative and hydrogel, we fabricated 3D nanopatterns by holographic lithography. Then, two-dimensional (2D) photolithography was combined to pattern the 3D structures. Eventually, we created a microfluidic channel with 3D periodic patterns. Since the 3D structure possess photonic bandgap properties as well as interconnected pore networks, this kind of microfluidic channel can be applied to optical sensors, mixers and filters.

Assays used in pharmaceutical research require a system that can not only detect biochemical interactions with high sensitivity, but that can also perform many measurements in parallel while consuming low volumes of reagents. While nearly all label-free biosensor transducers to date have been interfaced with a flow channel, the liquid handling system is typically aligned and bonded to the transducer for supplying analytes to only a few sensors in parallel. In this presentation, we describe a fabrication approach for photonic crystal biosensors that utilizes nanoreplica molding to produce a network of sensors that are automatically self-aligned with a microfluidic network in a single process step. The sensor/fluid network is inexpensively produced on large surface areas upon flexible plastic substrates, allowing the device to be incorporated into standard format 96-well microplates. A simple flow scheme using hydrostatic pressure applied through a single control point enables immobilization of capture ligands upon a large number of sensors with 220 nL of reagent, and subsequent exposure of the sensors to test samples. A high resolution imaging detection instrument is capable of monitoring the binding within parallel channels at rates compatible with determining kinetic binding constants between the immobilized ligands and the analytes. The first implementation of this system is capable of monitoring the kinetic interactions of 11 flow channels at once, and a total of 88 channels within an integrated biosensor microplate in rapid succession. The system was initially tested to characterize the interaction between sets of proteins with known binding behavior.

We present the design and operation of low-threshold and widely tunable polymer-based nanofluidic distributed feedback (DFB) dye lasers. The devices rely on light-confinement in a nanostructured polymer film embedded between two substrates. An array of nanofluidic channels forms a Bragg grating DFB laser resonator relying on the third order Bragg reflection. The lasers are fabricated by Combined Electron beam and UV Lithography (CEUL) in a thin film of SU-8 resist and polymer mediated wafer bonding. The devices are operated without the need for external fluidic handling apparatus. Capillary action drives the liquid dye infiltration of the nanofluidic DFB lasers and accounts for dye replenishment. The low Bragg reflection order yields: (i) low out-of-plane scattering losses, (ii) low coupling losses for the light when traversing the dye-filled nanofluidic channels due to the sub-wavelength dimensions of the resonator segments, and (iii) a large free spectral range (FSR). Points (i)+(ii) enable a low threshold for lasing, point (iii) facilitates wavelength tuning over the full gain spectrum of the chosen laser dye without mode-hopping. By combining different grating periods and dye solution refractive indices, we demonstrate a tuning range of 45 nm using a single laser dye and obtain laser threshold fluences down to ~ 7 μJ/mm². The lasers are straightforward to integrate on lab-on-a-chip microsystems, e.g. for novel sensor concepts, where coherent light in the visible range is desired.

Here we present our work towards the development of Nanoscale Optofluidic Sensor Arrays (NOSA), which is an optofluidic architecture for performing label free, highly parallel, detections of biomolecular interactions. The approach is based on the use of optically resonant devices whose resonant wavelength is shifted due to a local change in refractive index caused by a positive binding event between a surface bound molecule and it solution phase target. A special two stage micro-/nanofluidics architecture is used to first functionalize the devices and then to deliver the targets. Two variants of the NOSA will be presented here. The first approach utilizes a 1D resonant cavity in a 1D silicon-on-insulator (SOI) waveguide with a unique differential size functionalization approach. This approach allows binding events at one or at a combination of the many sensing sites which causes a unique shift in the output resonator spectrum. The latter approach consists of a SOI waveguide evanescently coupled to multiple 1-D photonic crystal resonators of different sizes along the length, each of which is functionalized with a different oligonucleotide probe. These devices have an extremely low limit of detection and are compatible with aqueous environments. The primary advantage of these devices over existing technology is that it combines the sensitivity (limit of detection) of nanosensor technology with the parallelism of the microarray type format. Our initial application is in the detection of viral RNA of Dengue virus.

We propose and demonstrate a new type of a photonic crystal nanolaser integrated into a microfluidic chip, which is fabricated by multilayer soft lithography. Experimentally, continuous-wave operation of the lasing action has been observed owing to efficient water-cooling. Characteristics of wavelength tuning by the fluid are investigated using both theory and experiment. In addition, we propose that dynamic modulation of far-field radiation pattern can be achieved by introducing a bottom reflector and by flowing the fluid on it. Especially, by choosing effective one-wavelength distance between the reflector and the cavity, efficient unidirectional emission can be obtained.

In this paper we theoretically discuss how a strongly dispersive photonic crystals environment may be used to enhance the light-matter interactions, thus potentially compensating for the reduced optical path in typical lab-on- a-chip systems. Combining electromagnetic perturbation theory with full-wave electromagnetic simulations we address the prospects for slow-light enhancement of Beer-Lambert absorption and photonic band-gap based refractometry.

Current optical storage devices such as DVDs have their read/write capabilities fundamentally restricted by the diffraction limit of light. We present an optofluidic architecture for storing cocktails of colloidal quantum dots in electroactive nanowell structures. One application of these devices is the development of a fluidic memory approach which could enable the generation, reading and erasing of multiple bit information packages on single light diffraction limited data marks by spectral and intensity multiplexing of quantum dot cocktails. Here we focus on the development of the electroactive nanowell trapping architecture. Briefly, we have shown that by applying an electric potential between a top and bottom Indium Tin Oxide (ITO) electrodes, particles ranging from 5μm polystyrene spheres to 5nm quantum dots suspended in solution can be attracted, stored and rejected from a targeted well structure by electrokinetic actuation. Nanowells 100 nm in diameter and 1 μm deep were fabricated by depositing silicon and a small oxide thin film on top of an ITO cover slip, patterning the wells on electron beam resist followed by a series of dry etching steps that leave the ITO substrate exposed in the well sites. When the quantum dots are electrokinetically transported to their sensing sites, they are then excited by a UV-blue light, and their discrete fluorescent signal is captured by a fiber spectrometer. Data erasure can be selectively performed by reversing the polarity of the field and ejecting the quantum dots from the nanowell data marks.

Fluids with magnetic characteristics have important values for today applications. This fluids, so called ferrofluids or magnetic fluids are in general formed by small nanoparticles with mean diameters about 10 nm and a carrier liquid. In our work we present nanopowders obtained by laser pyrolysis, which have characteristics for magnetic fluids applications. The important feature of powder was determined by means of XRD and electron microscopy techniques. The nanopowders have sizes distributed in interval from 2 nm to 10 nm. The high resolution images exhibits single particles with magnetic monodomain. Also, we investigate nanoparticles for defects. The nanoparticles forms nanoclusters, and high resolution image show adjacent particles without interface, the coupling mode is only magnetic not chemical. The powders are composed by magnetite and maghemite phase determined from XRD data, and confirmed by SAED and HRTEM work. The cell parameter calculated from the (220), (311), (511) (440) peaks of sample SF32 is 0.835 nm equal to the maghemite cell parameter.

Biocompatibility of photoluminescent silicon nanocrystals was tested using standard cytotoxicity protocols with murine macrophage cell line RAW 264.7. We investigated the cytotoxicity and inflammatory responses of cells exposed to silicon nanocrystals by several biological endpoints. Cell death ratio, morphological changes, and the levels of nitric oxide production were studied. Spatial position of the nanoparticles relative to cell body was investigated using fluorescent microscopy. No statistically significant cytotoxicity or inflammatory response was detected with autoclaved silicon nanoparticles at concentrations up to 20 μg/ml in RAW 264.7 cells. The present study of murine macrophages, exposed to autoclaved silicon nanocrystals, will help define safety requirements for comparable nanoparticle biomedical applications.

Light-induced inactivation of dynamic response of somatic frog nerve on electrical pulsed excitation was study ex vivo. The light-sensitive Indocianin Green has been used on photodynamic induced inactivation of the processes generation nerve pulses. Inactivation of consequence action potential of somatic frog nerve using excitation of electrical pulsed was achieved by irradiation with diode laser light in a IR spectral region (λ=810 nm, P~1W/cm²) in the case of Indocianin green. It was discovered that Indocianine green decrease of the amplitude compound action potential of the ensemble neurons. Experiments show effective destruction of cancer cells of ear, mouth and skin by local injection of plasmon resonant gold nanoshells and semiconductor laser (810 nm) irradiation. For destruction such tumors pulse duration was not less than 1microsecond and pulse separation 10 at average power density 1-3 W/sm² and energy density 100-200 J/sm²

In this paper, two lithographic fabrication processes for magnetic tunnel junctions (MTJs) with different mask designs and etching technologies are discussed. The advantages and disadvantages of both processes are compared. The crucial steps to protect the oxide insulating barriers and avoid side-wall redepositions (which may lead to short circuits) are developed, and important design considerations of the mask patterns and the device geometric structures are elaborated. We show that implementing the strategies developed greatly increases the successful manufacturing yield of MTJ magnetoelectronics devices.

Bragg reflecting waveguide devices are fabricated on a flexible substrate by using a post lift-off process in order to provide highly uniform grating patterns on a wide range. In this process, the flexible substrate spin-coated on silicon wafer is released after the final fabrication process of chip dicing. The fabricated flexible Bragg reflector shows very sharp transmission spectrum with 3-dB bandwidth of 0.1 nm and 10-dB bandwidth of 0.4 nm, which proves the Bragg reflector has excellent uniformity. To achieve athermal operation of the flexible Bragg reflector, thermal expansion property of the plastic substrate is controlled by the thickness of two polymer materials constructing the plastic substrate. The flexible substrate with 0.7-μm SU-8 layers sandwiching 100-μm NOA61 layer provides an optimized thermal expansion property to compensate the thermo-optic effect of the waveguide made of ZPU polymer. The temperature dependence of the Bragg reflector is decreased to -0.011 nm/°C through the incorporation of the plastic substrate.

Aluminum fluoride thin films have been deposited by magnetron sputtering of aluminum target with CF₄ , or CF₄ mixed 5% O₂ as working gas. To obtain low optical loss and high packing density, the films were investigated under different sputtering power and substrate temperatures. Their optical properties (including the transmittance, refractive index, and extinction coefficient) in the UV range and microstructure (including the cross section morphology, surface roughness, and crystallization) have been studied. AlF₃ thin films deposited at low temperature and low sputtering power have better optical quality. The extinction coefficient of AlF₃ thin films coated by 25W with CF₄ mixed 5% O₂ as working gas is smaller than 6.5×10^-4 in the wavelength range of 190nm to 300nm

Oblique deposition of lanthanum fluoride thin films was prepared by thermal resistance evaporation. The characteristics (including microstructure, coefficient of tangent rule, birefringence at 193nm and stress) of lanthanum fluoride thin films of have been investigated. The deposition angles increased from 20 to 70 degree, the coefficient of tangent rule decreased from 0.7 to 0.37. When the deposition angles larger than 60 degree, the coefficient held a constant, 0.37. The refractive index at 193nm of oblique deposition films decreased with the deposition angles was larger than 40 degree. The residual stress of films achieved the minimum value at 20-degree deposition angle.

A nanoscale linked-crater structure was fabricated on an Al surface by chemical and electrochemical combination processes. The surface of an Al plate was treated with Semi Clean and was successively processed in anodization in H₂SO₄. Dynamic force microscopy image (DFM) showed that a linked-crater structure was formed on the Al surface. At the next stage, the authors conducted the thin film growth of conducting polymer polythiophene on the Al surface by an electrochemical method. The electrochemical polymerization on the Al surface was performed in acetonitrile containing thiophene monomer and (Et)₄NBF₄ as a supporting electrolyte. After being electrochemically processed, the contour image of each crater was still recognized implying that the polymer nanofilm was grown on the nanoscale structured Al surface. The cross section analysis demonstrated that the nanofilm was grown along the linked-crater structure because the contour of each crater became thick. X-ray photoemission spectroscopy measurement also supported the polymer nanofilm growth because C 1s and S 2p lines were detected. Furthermore, copper phthalocyanine (CuPc) molecules are injected into the polymer nanofilm grown on the nanoscale structured Al surface by diffusing method in order to functionalize the nanoscale hybrid material.

In this work we report on the study of the photopolymerization process in hybrid organic-inorganic films containing photopolymerizable acrylic and methacrylic groups and. The films are doped with a proper photo-initiator for radical polymerization of (meth)acrylic units and are prepared using the sol-gel technique. The photo-initiator is activated by using continuum (single-photon polymerization) or pulsed (two-photon polymerization) laser sources at different wavelengths. After the development of the unexposed regions with a suitable solvent, the photopolymerized structures are observed with microscopy techniques. The effects of the composition of the photopolymerizable mixture, the irradiation parameters (laser power and exposure time) and the external atmosphere in which the photopolymerization is performed are investigated. The fabrication of 3D microstructures using multiphoton absorption processes is a promising technique that involves low amount of incident exposure dose with potentially high spatial resolution.

We present a theoretical analysis and numerical design of bent and branched sections of coupled resonator optical waveguides (CROWs) composed of side-coupled whispering-gallery (WG) mode microdisk resonators. Our analysis is based on a rigorous Muller boundary integral equations method that enables accurate treatment of CROWs consisting of both identical and different microdisks as well as studying CROW finite-size effects. Differences in WG modes coupling in the vicinity of bends in CROWs composed of optically-large and wavelength-scale microcavities are revealed and discussed. We propose possible ways of pre- and post-fabrication tuning of bent CROW sections. At the pre-fabrication design stage, adjusting the radius of the microdisk positioned at the CROW bend may yield significant reduction of bend losses for any chosen CROW bend angle. Post-fabrication tuning capability of the designed structures is also discussed.

We have covalently attached multiple fluorescent silicon nanocrystals (SNs) to streptavidin molecule. Selective conjugation of SNs to a target protein is accomplished using sequential silicon surface termination chemistry. In the first step, freshly prepared hydrogen terminated surfaces of SNs are substituted with alkane monolayer that serves as a platform for chemical linkage to hetero bifunctional crosslinker (4-azido-2,3,5,6-tetrafluorobenzoic acid, succinimidyl ester), and provides optical and chemical stabilities against oxidation and aggregation of nanoparticles. Next, an open end of bifunctional cross linker - diazirine succinimidyl ester forms an amide bond with a carboxyl of target protein. Gel electrophoresis of SNs labeled streptavidin clearly show separate elution of conjugation product and neat protein. Conjugate functionality was verified by allowing it to interact with biotinylated micro beads. A bright fluorescence, characteristic to SN's was observed from vigorously washed micro beads showing selective attachment of nanoparticle bearing streptavidin to biotinylated micro beads. High quantum yield of streptavidin-SN conjugate in combination with the biocompatibility of silicon nanoparticles presents an attractive platform for the fluorescent tagging in diverse bioassays.

Microstructure manipulation is a fundamental process to further the study of biology and medicine, as well as to advance micro- and nano-system applications. The manipulation of micro and nanostructures has been achieved through various microgripper devices developed recently, which lead to advances in single cell manipulation and micromachine assembly. However, the physical, mechanical, optical and chemical information about the microstructure under study is usually extracted from macroscopic instrumentation, such as confocal microscopy and Raman spectroscopy. In this paper we describe the design, simulation, fabrication and characterization (mechanical and optical) of a novel Micro-Opto-Electro-Mechanical-System (MOEMS) optical microgripper. This is the first device of this kind, which enables the direct manipulation, mechanical characterization, and simultaneous optical characterization of microstructures. Optical fluorescence measurements or identification, as well as absorption spectroscopy are possible with this new device. The device is implemented in SU-8 due to its suitable optical and mechanical properties. The current generation of the device was designed to manipulate structures with dimensions lower than ~5 μm.

The collecting and sorting micro size particles by electric force is easy to integrate with other bioassays. There are many forms of electric forces such as electrophoresis, dielectrophoresis and electroosmosis which can be used to manipulate particles. In an attempt to understand the role of electroosmosis and dielectrophoresis in the collection of micro size particles, a small device made of two parallel plates is used to study the particle movement under AC electric field. The device is fabricated by a top electrode and a bottom electrode separated by a spacer. The top electrode is made from an ITO glass where the bottom electrode is made of Corning 1737 glass sputtered with chromium. A dielectric layer is fabricated by spin coating a thin photo-resist (0.5~1μm) on the bottom electrode and a spacer made of curing PDMS is utilized to separate these electrodes. A 900μm × 900μm collecting chamber is fabricated on the bottom electrode via photolithography. The amine-modified polystyrene fluorescent particles whose average size is 1 μm were used for collection experiments. Different frequency and power were applied to generate the non-uniform electric field. It was found that frequency is the critical factor for electroosmotic velocity. There seems to be an optimum frequency that leads to largest particle velocity. The underlying mechanism is believed to the competing forces among dielectrophoresis and electroosmosis. This device demonstrates that the electroosmosis force is suitable for collecting bio-particles in AC electric field.

In the paper, we design a sub-wavelength level polarizer to replace the traditional polarizer in various optical applications. The structure of the polarizer is a one-dimension periodic grating. It has three layers with different materials. We do the basic design by using "Effective Medium Theorem." And we verify and improve the result by using rigorous couple-wave analysis (RCWA). In the range of visible wavelength, the polarizer has high contrast and high tolerance of incident angle in three-dimension space.

The prediction of the effects on the dielectric constant in thin film dielectrics is of interest in a variety of electronic applications ranging from microelectronics to displays and MEMS applications. This paper discusses the link between the molecular structure of a silicate spin-on dielectric and the final processed dielectric constant by relating trends in the calculated dielectric constant using Density Functional Theory to measurements made on thin films produced during formulation and cure studies. For this investigation, silanol and water content, film density and stress were varied both computationally and experimentally in order to understand the trade-off contributing toward the final dielectric constant. It was found that there is a non-trivial relationship between all these variables which relates back to the molecular structure of the final material, expressed by the density and the stress state of the material. This underlines the importance of finding stable processes in order to produce reproducible films.