http://www.hindawi.comThe latest articles from Hindawi Publishing Corporation© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/134215.htmlStoyan Tanev, Brian C. Wilson, Valery V. Tuchin, and Dennis Matthews© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/727418.htmlA new 3D simulation method based on the finite-difference time domain (FDTD) approach in combination with Fourier optic techniques is applied to the modeling of optical phase contrast microscope (OPCM) imaging of gold nanoparticles (NPs) in singe biological cells. We consider a realistic size 3D cell model at optical immersion conditions, that is, when the refractive index values of the cytoplasm and of the extracellular medium are equal. For the first time, an FDTD-based OPCM model is applied to visualize the presence of a cluster of gold NPs in the cytoplasm at both resonant and nonresonant conditions. The results demonstrate the capability to model OPCM image enhancement by optically controlling the resonant properties of the NPs. Our research study extends the applicability of the FDTD modeling approach into a new biomedical optics research area.Stoyan Tanev, James Pond, Paul Paddon, and Valery V. Tuchin© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/417976.htmlThe color image quality of presentation programs is evaluated and measured using S-CIELAB and CIEDE2000 color difference formulae. A color digital image in its original format is compared with the same image already imported by the program and introduced as a part of a slide. Two widely used presentation programs—Microsoft PowerPoint 2004 for Mac and Apple's Keynote 3.0.2—are evaluated in this work.Edison Valencia and María S. Millán© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/532368.htmlA 3-chip CCD imaging system has been developed for quantitative in vivo fluorescence imaging. This incorporates a ratiometric algorithm to correct for the effects of tissue optical absorption and scattering, imaging “geometry” and tissue autofluorescence background. The performance was characterized, and the algorithm was validated in tissue-simulating optical phantoms for quantitative measurement of the fluorescent molecule protoporphyrin IX (PpIX). The technical feasibility to use this system for fluorescence-guided surgical resection of malignant brain tumor tissue was assessed in an animal model in which PpIX was induced exogenously in the tumor cells by systemic administration of aminolevulinic acid (ALA).Eduardo H. Moriyama, Anthony Kim, Arjen Bogaards, Lothar Lilge, and Brian C. Wilson© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/862081.htmlDelta-aminolevulinic acid/protoporphyrin IX is applied for fluorescent tumor detection in the upper part of gastrointestinal tract. The 5-ALA is administered per os six hours before measurements at dose 20 mg/kg weight. High-power light-emitting diode at 405 nm is used as an excitation source. Special opto-mechanical device is built to use the light guide of standard video-endoscopic system. Through endoscopic instrumental channel a fiber is applied to return information about fluorescence to microspectrometer. In such way, 1D detection and 2D visualization of the lesions' fluorescence are received, and both advantages and limitations of these methodologies are discussed in relation to their clinical applicability. Comparison of the spectra received from normal mucosa, inflammatory, and tumor areas is applied to evaluate the feasibility for development of simple but effective algorithm based on dimensionless ratio of the fluorescence signals at 560 and 635 nm, for differentiation of normal/abnormal gastrointestinal tissues.Ekaterina Borisova, Borislav Vladimirov, and Latchezar Avramov© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/797214.htmlAutonomic dysreflexia (AD) is an inappropriate response of the sympathetic nervous system that commonly occurs when individuals with spinal cord injury (SCI), at or above the sixth thoracic (T6) vertebra, are subjected to a noxious stimulus below the level of injury. An AD event can be put into motion by something as simple as an ingrown toenail or a full bladder, with symptoms ranging from headache, high blood pressure, and even stroke. We have characterized the onset of AD and resulting autonomic events in an individual with SCI using a fiberoptic-based probe. Two probes were located above and below the injury level, on the subjects forearm and thigh, respectively, and were connected to a dual channel spectrophotometer. Oxygen saturation was calculated using the reflectance spectra and an algorithm based on melanin and hemoglobin absorption. We noticed that during an AD event the amount of oxygen in the skin below the injury level dropped by as much as 40%, while above the injury level, skin oxygenation remained constant. In addition, we found that the level of skin perspiration below the level of injury increased significantly. We hypothesize that the combination of AD-related ischemia with pressure-related ischemia and increased perspiration places individuals with spinal cord injury level at T6 or above at an elevated risk for developing a pressure sore below the injury site.J. C. Ramella-Roman and J. M. Hidler© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/510937.htmlPavel Cheben, Richard Soref, David Lockwood, and Graham Reed© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/359760.htmlNumerous models have been developed for calculating optimum decision rules for nitrogen fertilization based on remote sensing techniques. New technologies related to digital image analysis may provide an alternative method to estimate nutrient status faster and more efficiently than current techniques. A series of field studies was conducted to determine the applicability of digital image analysis for nitrogen demand estimates in broccoli plants. Digital images were taken under constant light conditions in various wavelength ranges (380–1300 nm) using a digital imager. Images were processed for the parameters a∗ and b∗ in the L∗a∗b∗ color system. The image analysis showed a close correlation between the nitrogen status of broccoli plants and the parameter b∗ of the L∗a∗b∗ color system especially in the wavelength ranges 510780 and 516780 nm. The relationship between nutrient concentration in leaf dry matter and the parameters b∗ was used to determine the N fertilizer demand within the cultivation period. Estimated N amounts were applied as top dressing four weeks after setting and were 100 kg ha−1 lower than the standard fertilizer rate. Calculated N balances indicated a total uptake of applied N amounts in the image-based N treatments without considerable yield loss. Thus, digital image analysis proved to be an effective means of determining nitrogen status and adjusting fertilizer applications to preserve or enhance crop quality and yield considering sustainability.Simone Graeff, Judit Pfenning, Wilhelm Claupein, and Hans-Peter Liebig© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/293531.htmlTransistor scaling alone can no longer be relied upon to yield the exponential speed increases we have come to expect from the microprocessor industry. The principle reason for this is the interconnect bottleneck, where the electrical connections between and within microprocessors are becoming, and in some cases have already become, the limiting factor in overall microprocessor performance. Optical interconnects have the potential to address this shortcoming directly, by providing an inter- and intrachip communication infrastructure that has both greater bandwidth and lower latency than electrical interconnects, while remaining safely within size and power constraints. In this paper, we review the requirements that a successful optical interconnect must meet, as well as some of the recent work in our group in the area of slow-light photonic crystal devices for on-chip optical interconnects. We show that slow-light interferometric optical modulators in photonic crystal can have not only high bandwidth, but also extremely compact size. We also introduce the first example of a multichannel slow light platform, upon which a new class of ultracompact optical devices can be built.Sean P. Anderson, Ashutosh R. Shroff, and Philippe M. Fauchet© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/685489.htmlFirst implementations of subwavelength gratings (SWGs) in silicon-on-insulator (SOI) waveguides are discussed and demonstrated by experiment and simulations. The subwavelength effect is exploited for making antireflective and highly reflective waveguide facets as well as efficient fiber-chip coupling structures. We demonstrate experimentally that by etching triangular SWGs into SOI waveguide facets, the facet power reflectivity can be reduced from 31% to <2.5%. Similar structures using square gratings can also be used to achieve high facet reflectivity. Finite difference time-domain simulations show that >94% facet reflectivity can be achieved with square SWGs for 5 μm thick SOI waveguides. Finally, SWG fiber-chip couplers for SOI photonic wire waveguides are introduced, including design, simulation, and first experimental results.J. H. Schmid, P. Cheben, S. Janz, J. Lapointe, E. Post, A. Delâge, A. Densmore, B. Lamontagne, P. Waldron, and D.-X. Xu© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/908246.htmlThe spectral properties of novel styryl dyes developed for the biomacromolecules (such as DNA) detection and imaging were investigated. The energy structures of dye molecules were examined. The spectral data prove that dyes aggregate and interact with DNA. The essential increase of the fluorescence intensity of dyes in the presence of DNA was observed. The photostability and phototoxic influence on the DNA of several styryl dyes were studied by analyzing absorption, fluorescence, and phosphorescence spectra of these dyes and dye-DNA systems. Changes of the optical density value of dye-DNA solutions caused by the irradiation were fixed in the DNA and dye absorption wavelength regions. Fluorescence emission of dye-DNA complexes upon two-photon excitation at wavelength 1064 nm with the 20-nanosecond pulsed YAG:Nd3+ laser and at 840 nm with the 90 famtosecond pulsed Ti:sapphire laser was registered. The values of two-photon absorption cross-sections of dye-DNA complexes were evaluated.V. M. Yashchuk, S. M. Yarmoluk, V. Yu. Kudrya, M. Yu. Losytskyy, V. P. Tokar, V. M. Kravchenko, V. B. Kovalska, A. O. Balanda, and D. V. Kryvorotenko© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/807457.htmlIntegrated photonics via Si CMOS technology has been a strategic area since electronics and photonics convergence should be the next platform for information technology. The platform is recently referred to as “Si photonics” that attracts much interest of researchers in industries as well as academia in the world. The main goal of Si Photonics is currently to reduce material diversity of photonic devices to pursuing CMOS-compatibility. In contrast, the present paper proposes another route of Si Photonics, reducing diversity of photonic devices. The proposed device unifying functionality of photonics is a microresonator with a pin diode structure that enables the Purcell effect and Franz-Keldysh effect to emit and to modulate light from SiGe alloys.Kazumi Wada© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/472305.htmlA brief overview of silicon photonics is given here in order to provide a context for invited and contributed papers in this special issue. Recent progress on silicon-based photonic components, photonic integrated circuits, and optoelectronic integrated circuits is surveyed. Present and potential applications are identified along with the scientific and engineering challenges that must be met in order to actualize applications. Some on-going government-sponsored projects in silicon optoelectronics are also described.Richard Soref© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/416926.htmlSilicon the material per excellence for electronics is not used for sourcing light due to the lack of efficient light emitters and lasers. In this review, after having introduced the basics on lasing, I will discuss the physical reasons why silicon is not a laser material and the approaches to make it lasing. I will start with bulk silicon, then I will discuss silicon nanocrystals and Er3+ coupled silicon nanocrystals where significant advances have been done in the past and can be expected in the near future. I will conclude with an optimistic note on silicon lasing.L. Pavesi© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/279502.htmlSilicon nanocrystals (NCs) represent one of the most promising material systems for light emission applications in microphotonics. In recent years, several groups have reported on the observation of optical gain or stimulated emission in silicon NCs or in porous silicon (PSi). These results suggest that silicon-NC-based waveguide amplifiers or silicon lasers are achievable. However, in order to obtain clear and reproducible evidence of stimulated emission, it is necessary to understand the physical mechanisms at work in the light emission process. In this paper, we report on the detailed theoretical aspects of the energy levels and recombination rates in doped and undoped Si NCs, and we discuss the effects of energy transfer mechanisms. The theoretical calculations are extended toward computational simulations of ensembles of interacting nanocrystals. We will show that inhomogeneous broadening and energy transfer remain significant problems that must be overcome in order to improve the gain profile and to minimize nonradiative effects. Finally, we suggest means by which these objectives may be achieved.V. A. Belyakov, V. A. Burdov, R. Lockwood, and A. Meldrum© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/254317.htmlThe technique of variable-angle total internal reflection fluorescence microscopy (TIRFM) and its application to nanotomography of cell surfaces are described. Present applications include (1) 3D imaging of chromosomes in their metaphase to demonstrate axial resolution in the nanometre range, (2) measurements of cell-substrate topology, which upon cholesterol depletion shows some loosening of cell-substrate contacts, and (3) measurements of cell topology upon photodynamic therapy (PDT), which demonstrate cell swelling and maintenance of focal contacts. The potential of the method for in vitro diagnostics, but also some requirements and limitations are discussed.Michael Wagner, Petra Weber, Wolfgang S. L. Strauss, Henri-Pierre Lassalle, and Herbert Schneckenburger© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/275080.htmlThe objective of this research program is to develop a novel, noninvasive, low-cost infrared (8–12 μm spectral range) imaging technique that would improve upon current methods using nanostructured core/shell magnetic/noble metal-based imaging and therapies. The biocompatible magnetic nanoparticles are able to produce heat under AC magnetic field. This thermal radiation propagates along the tissue by thermal conduction reaching the medium's (tissue's) surface. The surface temperature distribution is acquired by a thermal camera and can be analyzed to retrieve and reconstruct nanoparticles' temperature and location within the tissue. The technique may function as a diagnostic tool thanks to the ability of specific bioconjugation of these nanoparticles to tumor's outer surface markers. Hence, by applying a magnetic field, we could cause a selective elevation of temperature of the targeted nanoparticles up to 5∘C, which detects the tumor. Furthermore, elevating the temperature over 65∘C and up to 100∘C stimulates a thermo ablating interaction which causes a localized irreversible damage to the cancerous site with no harm to the surrounding tissue. While functioning as a diagnostic tool, this procedure may serve as a targeted therapeutic tool under thermal feedback control as well.Iddo M. Gescheit, Moshe Ben-David, and Israel Gannot© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/568936.htmlWe review our recent studies on all-optical switching and memory operations based on thermo-optic and carrier-plasma nonlinearities both induced by two-photon absorption in silicon photonic crystal nanocavities. Owing to high-Q and small volume of these photonic crystal cavities, we have demonstrated that the switching power can be largely reduced. In addition, we demonstrate that the switching time is also reduced in nanocavity devices because of their short diffusion time. These features are important for all-optical nonlinear processing in silicon photonics technologies, since silicon is not an efficient optical nonlinear material. We discuss the effect of the carrier diffusion process in our devices, and demonstrate improvement in terms of the response speed by employing ion-implantation process. Finally, we show that coupled bistable devices lead to all-optical logic, such as flip-flop operation. These results indicate that a nanocavity-based photonic crystal platform on a silicon chip may be a promising candidate for future on-chip all-optical information processing in a largely integrated fashion.Masaya Notomi, Takasumi Tanabe, Akihiko Shinya, Eiichi Kuramochi, and Hideaki Taniyama© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/780784.htmlIt is well known that robust and reliable photonic crystal structures can be manufactured with very high precision by electrochemical etching of silicon wafers, which results in two- and three-dimensional photonic crystals made of macroporous silicon. However, tuning of the photonic properties is necessary in order to apply these promising structures in integrated optical devices. For this purpose, different effects have been studied, such as the infiltration with addressable dielectric liquids (liquid crystals), the utilization of Kerr-like nonlinearities of the silicon, or free-charge carrier injection by means of linear (one-photon) and nonlinear (two-photon) absorptions. The present article provides a review, critical discussion, and perspectives about state-of-the-art tuning capabilities.Heinz-S. Kitzerow, Heinrich Matthias, Stefan L. Schweizer, Henry M. van Driel, and Ralf B. Wehrspohn© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/689715.htmlWe review the use of the oxide cladding stress-induced photoelastic effect to modify the polarization dependent properties in silicon-on-insulator (SOI) waveguide components, and highlight characteristics particular to this high index contrast (HIC) systems. The birefringence in SOI waveguides has its origin in the electromagnetic boundary conditions at the waveguide boundaries, and can be further modified by the presence of stress in the waveguiding materials. With typical stress levels in SiO2 films, which are often used as the upper cladding, the waveguide effective index can be altered anisotropically up to the order of 10−3 for ridges with heights ranging from 1 μm to 5 μm. This effect can be used effectively to counter the waveguide geometrical birefringence, allowing the waveguide cross-section profiles to be optimized for design criteria other than null geometrical birefringence. Design strategies are developed for using stress engineering to achieve a variety of functions. Polarization insensitive arrayed waveguide gratings (AWGs), polarization insensitive ring resonators, and polarization splitters and filters are demonstrated using these design principles.D.-X. Xu, W. N. Ye, S. Janz, A. Delâge, P. Cheben, B. Lamontagne, E. Post, and P. Waldron© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/725967.htmlWe review our work developing optical waveguide-based evanescent field sensors for the label-free, specific detection of biological molecules. Using high-index-contrast silicon photonic wire waveguides of submicrometer dimension, we demonstrate ultracompact and highly sensitive molecular sensors compatible with commercial spotting apparatus and microfluidic-based analyte delivery systems. We show that silicon photonic wire waveguides support optical modes with strong evanescent field at the waveguide surface, leading to strong interaction with surface bound molecules for sensitive response. Furthermore, we present new sensor geometries benefiting from the very small bend radii achievable with these high-index-contrast waveguides to extend the sensing path length, while maintaining compact size. We experimentally demonstrate the sensor performance by monitoring the adsorption of protein molecules on the waveguide surface and by tracking small refractive index changes of bulk solutions.A. Densmore, D.-X. Xu, S. Janz, P. Waldron, J. Lapointe, T. Mischki, G. Lopinski, A. Delâge, J. H. Schmid, and P. Cheben© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/615393.htmlWe propose a time-domain analysis of an active medium based on a coupled quantum mechanical and electromagnetic model to accurately simulate the dynamics of silicon-based photonic devices. To fully account for the nonlinearity of an active medium, the rate equations of a four-level atomic system are introduced into the electromagnetic polarization vector. With these auxiliary differential equations, we solve the time evolution of the electromagnetic waves and atomic population densities using the FDTD method. The developed simulation approach has been used to model light amplification and amplified spontaneous emission in silicon nanocrystals, as well as the lasing dynamics in a novel photonic crystal-based silicon microcavity.Shouyuan Shi, Brandon Redding, Tim Creazzo, Elton Marchena, and Dennis W. Prather© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/678948.htmlThis paper describes the recent advances made in silicon optical modulators employing the free carrier dispersion effect, specifically those governed by majority carrier dynamics. The design, fabrication, and measurements for two different devices are discussed in detail. We present an MOS capacitor-based modulator delivering 10 Gbps data with an extinction ratio of ∼4 dB and a pn-diode-based device with high-speed transmission of 40 Gbps and bandwidth greater than 30 GHz. Device improvements for achieving higher extinction ratios, as required for certain applications, are also discussed. These devices are key components of integrated silicon photonic chips which could enable optical interconnects in future terascale processors.Juthika Basak, Ling Liao, Ansheng Liu, Doron Rubin, Yoel Chetrit, Hat Nguyen, Dean Samara-Rubio, Rami Cohen, Nahum Izhaky, and Mario Paniccia© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/196572.htmlWe discuss our approach to monolithic intergration of Ge photodectors with CMOS electronics for high-speed optical transceivers. Receivers based on Ge waveguide photodetectors achieve a sensitivity of −14.2 dBm (10−12 bit error rate (BER)) at 10 Gbps and 1550 nm.Gianlorenzo Masini, Subal Sahni, Giovanni Capellini, Jeremy Witzens, and Cary Gunn© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/218032.htmlThree-dimensional SiGe nanostructures grown on Si (SiGe/Si) using molecular beam epitaxy or low-pressure chemical vapor deposition exhibit photoluminescence and electroluminescence in the important spectral range of 1.3–1.6 μm. At a high level of photoexcitation or carrier injection, thermal quenching of the luminescence intensity is suppressed and the previously confirmed type-II energy band alignment at Si/SiGe cluster heterointerfaces no longer controls radiative carrier recombination. Instead, a recently proposed dynamic type-I energy band alignment is found to be responsible for the strong decrease in carrier radiative lifetime and further increase in the luminescence quantum efficiency.L. Tsybeskov, E.-K. Lee, H.-Y. Chang, B. V. Kamenev, D. J. Lockwood, J.-M. Baribeau, and T. I. Kamins© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/412518.htmlPhotonics on CMOS is the integration of microelectronics technology and optics components to enable either improved functionality of the electronic circuit or miniaturization of optical functions. The integration of a photonic layer on an electronic circuit has been studied with three routes. For combined fabrication at the front end level, several building blocks using a silicon on insulator rib technology have been developed: slightly etched rib waveguide with low (0.1 dB/cm) propagation loss, a high speed and high responsivity Ge integrated photodetector and a 10 GHz Si modulators. Next, a wafer bonding of silicon rib and stripe technologies was achieved above the metallization layers of a CMOS wafer. Last, direct fabrication of a photonic layer at the back-end level was achieved using low-temperature processes with amorphous silicon waveguide (loss 5 dB/cm), followed by the molecular bonding of InP dice and by the processing in microelectronics environment of InP μsources and detector.J. M. Fedeli, L. Di Cioccio, D. Marris-Morini, L. Vivien, R. Orobtchouk, P. Rojo-Romeo, C. Seassal, and F. Mandorlo© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/682978.htmlThis paper reviews the recent progress of hybrid silicon evanescent devices. The hybrid silicon evanescent device structure consists of III-V epitaxial layers transferred to silicon waveguides through a low-temperature wafer bonding process to achieve optical gain, absorption, and modulation efficiently on a silicon photonics platform. The low-temperature wafer bonding process enables fusion of two different material systems without degradation of material quality and is scalable to wafer-level bonding. Lasers, amplifiers, photodetectors, and modulators have been demonstrated with this hybrid structure and integration of these individual components for improved optical functionality is also presented. This approach provides a unique way to build photonic active devices on silicon and should allow application of silicon photonic integrated circuits to optical telecommunication and optical interconnects.Hyundai Park, Alexander W. Fang, Di Liang, Ying-Hao Kuo, Hsu-Hao Chang, Brian R. Koch, Hui-Wen Chen, Matthew N. Sysak, Richard Jones, and John E. Bowers© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/383927.htmlIn the last two decades, we have witnessed a remarkable progress in the development of biosensor devices and their application in areas such as environmental monitoring, biotechnology, medical diagnostics, drug screening, food safety, and security, among others. The technology of optical biosensors has reached a high degree of maturity and several commercial products are on the market. But problems of stability, sensitivity, and size have prevented the general use of optical biosensors for real field applications. Integrated photonic biosensors based on silicon technology could solve such drawbacks, offering early diagnostic tools with better sensitivity, specificity, and reliability, which could improve the effectiveness of in-vivo and in-vitro diagnostics. Our last developments in silicon photonic biosensors will be showed, mainly related to the development of portable and highly sensitive integrated photonic sensing platforms.Kirill Zinoviev, Laura G. Carrascosa, José Sánchez del Río, Borja Sepúlveda, Carlos Domínguez, and Laura M. Lechuga© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/315724.htmlThe design and simulations of planar reflective gratings for building optical interconnects in silicon-on-insulator (SOI) were studied for a range of silicon core thicknesses of 0.1 to 10 μm. The verticality of the grating facets has been shown to be the main contributing factor to the cumulative crosstalk in thick silicon cores. The dispersion property of the slab was found to limit the minimal thickness of the core for polarization-insensitive gratings. The effects of polarization-dependent confinement on optical crosstalk were studied. The findings were used to design and simulate a polarization-insensitive 18-channel coarse wavelength division demultiplexer (CWDM) with a free spectral range of over 600 nm. The CWDM demultiplexer uses a 1.7 μm silicon core and combines a shallow-etch tapered rib structure and multimode silicon channels to produce box-like passbands for integrated receiver applications. The diffraction grating was constructed using double astigmatic point design with phase-corrected grating facets to reduce astigmatism. Optical properties of the planar gratings have been simulated using quasivectorial diffraction grating theory. The simulation results confirm that there is high diffraction efficiency and low optical crosstalk over the entire range of operation. Applications of planar silicon gratings to the synthesis of silicon interconnects are discussed.Ronald Millett, Jamie Ramsey, Przemek Bock, Julie Nkanta, Henry Schriemer, Trevor J. Hall, and Serge Bidnyk© 2010, Hindawi Publishing Corporation. All rights reserved.http://www.hindawi.com/journals/aot/2008/267867.htmlWe present experimental results on optical properties of cranial bone controlled by administration of propylene glycol and glycerol. Both transmittance and reflectance spectra of human and porcine cranial bone in vitro were measured. For estimation of absorption and reduced scattering coefficients of the bone, the inverse adding-doubling method was used. The decrease of reflectance of the samples under action of the immersion agents was demonstrated. The experiments have shown that administration of the immersion liquids allows for effective controlling of tissue optical characteristics that makes bone more transparent, thereby increasing the ability of light penetration through the tissue. The presented results can be used in developing of functional imaging techniques, including OCT.Elina A. Genina, Alexey N. Bashkatov, and Valery V. Tuchin© 2010, Hindawi Publishing Corporation. All rights reserved.