Advances In Optical Technology Research Articles

Reassessing the Role of Intra-Arterial Drug Delivery for Glioblastoma Multiforme Treatment.

Effective treatment for glioblastoma (GBM) will likely require targeted delivery of several specific pharmacological agents simultaneously. Intra-arterial (IA) delivery is one technique for targeting the tumor site with multiple agents. Although IA chemotherapy for glioblastoma (GBM) has been attempted since the 1950s, the predicted benefits remain unproven in clinical practice. This review focuses on innovative approaches to IA drug delivery in treating GBM. Guided by novel in vitro and in vivo optical measurements, newer pharmacokinetic models promise to better define the complex relationship between background cerebral blood flow and drug injection parameters. Advanced optical technologies and tracers, unique nanoparticles designs, new cellular targets, and rational drug formulations are continuously modifying the therapeutic landscape for GBM. Personalized treatment approaches are emerging; however, such tailored approaches will largely depend on effective drug delivery techniques and on the ability to simultaneously deliver multidrug regimens. These new paradigms for tumor-selective drug delivery herald dramatic improvements in the effectiveness of IA chemotherapy for GBM. Therefore, within this context of so-called “precision medicine,” the role of IA delivery for GBM is thoroughly reassessed.

Baseband unit cloud interconnection enabled by flexible grid optical networks with software defined elasticity

The evolution toward 5G mobile networks is characterized by supporting higher data rate, excellent end-to-end performance and ubiquitous user-coverage with lower latency, power consumption, and cost. To support this, the RANs are evolving in two important aspects. One aspect is “cloudification,” which is to pool baseband units to be centralized for statistical multiplexing gain. The other aspect is to use advanced optical technologies for digital and analog signal transmission in a cloud-based RAN. In this article, we focus on BBU cloud interconnection with optical layer technologies. Flexible grid optical networks with the enabling technologies are introduced to provide elastic, transparent, and virtualized optical paths between the BBU pools. To improve the elasticity and intelligence of C-RAN, we propose a software defined centralized control plane to coordinate heterogeneous resources from three domains: the BBU domain, radio domain, and optical domain. We report an experimental demonstration of elastic lightpath provision for cloud radio-over-flexible grid optical networks in a software-defined-networking-based testbed.

Multimodal Imaging Spectroscopy of Tissue.

Advanced optical imaging technologies have experienced increased visibility in medical research, as they allow for a label-free and nondestructive investigation of tissue in either an excised state or living organisms. In addition to a multitude of ex vivo studies proving the applicability of these optical imaging approaches, a transfer of various modalities toward in vivo diagnosis is currently in progress as well. Furthermore, combining optical imaging techniques, referred to as multimodal imaging, allows for an improved diagnostic reliability due to the complementary nature of retrieved information. In this review, we provide a summary of ongoing multifold efforts in multimodal tissue imaging and focus in particular on in vivo applications for medical diagnosis. We also discuss the advantages and potential limitations of the imaging methods and outline opportunities for future developments.

10 Best reviews and tutorials in Advanced Optical Technologies

10 Best reviews and tutorials in Advanced Optical Technologies

Fisheye lens conoscopy

Conoscopy is the visualisation of the birefringence of materials using depolarisation of light passing through with a broad range of incident orientations. In recent years, conoscopy has become an important optical tool in the science of soft materials, such as liquid crystals and polymers, and is widely applied in materials engineering and development, for example in technologies ranging from display optics to plastic food packaging. This paper reports ‘fisheye lens conoscopy’, a fundamentally new and broadly applicable optical approach to conoscopy that is particularly appropriate for the study of soft materials. These capabilities are illustrated using a fisheye lens system to characterise birefringent and polarising polymer films and liquid crystal test cells. In addition to birefringence measurement, fisheye conoscopic determination of the emission characteristics of commercial light emitting devices such as liquid crystal displays and the transmission of topographically patterned light control films is presented, demonstrating that fisheye methodology can be broadly applied to determine the angular dependence of light emission or transmission in advanced optical technologies and applications.

Evaluation of tooth preparations for Class II cavities using magnification loupes among dental interns and final year BDS students in preclinical laboratory.

Background:With the advances in optical technology, dentistry has been benefitted in varied ways over the ages.Aim:The aim of this study was to assess the effect of dental magnification loupes on psychomotor skill acquisition during preclinical operative exercise.Methods:40 Typhodont teeth tooth no. 36 and 46 (Frasaco - U.S.A.) were mounted on the acrylic lower jaw base of Phantom Head. Teeth are prepared for class II (MO) cavity with conservative design using micromotor, mouth mirror and probe. Tooth no.36 was prepared using magnifying loupes while tooth no.46 was prepared without the loupes. Data collected was statistically analyzed using Chi square test.Results:The results revealed that tooth preparations were better under magnifying loupes as compared to those without it with statistically significant difference with Kappa value 0.64 for samples with loupes and 0.76 for without loupes. Moreover, the study samples expressed their difficulty for using the magnifying loupes during the tooth preparation since they were using it for the first time.Conclusions:Magnifying loupes help the dental students to have better vision, thus improved dexterity with hands while preparing the tooth for restoration. However, dental students have to get adapted to the loupes for the ease of using loupes. Using loupes frequently may help them to get adapted to the loupes.

High-Speed Coherent Transmission Using Advanced Photonics in Terahertz Bands

SUMMARY A terahertz-wave communication system directly connected to an optical fiber network is promising for application to future mobile backhaul and fronthaul links. The possible broad bandwidth in the terahertz band is useful for high-speed signal transmission as well as radio-space encapsulation to the high-frequency carrier. In both cases, the low-latency feature becomes important to enhance the throughput in mobile communication and is realized by waveform transport technology without anydigital-signal-processing-based media conversion. A highlyprecise optical frequency comb signal generated by optical modulation and the vector signal demodulation technology adopted from advanced optical fiber communication technologies help perform modulation and demodulation with impairment compensation at just the edges of the link. Terahertz wave, radio over fiber, waveform transport, coherent detection, multilevel modu

Coherent Terahertz Wireless Signal Transmission Using Advanced Optical Fiber Communication Technology

Coherent terahertz signal transmission with multilevel modulation and demodulation is demonstrated using an optical sub-harmonic IQ mixer (SHIQM), which consists of optical components in advanced optical fiber communication technologies. An optical-frequency-comb-employed signal generator is capable of vector modulation as well as frequency tunability. Digital signal processing (DSP) adopted from the recently developed optical digital coherent communication can easily demodulate multi-level modulated terahertz signals by using electrical heterodyning for intermediate-frequency (IF) down conversion. This technique is applicable for mobile backhauling in the next-generation mobile communication technology directly connected to an optical fiber network as a high-speed wireless transmission link.

Varifocal MOEMS fiber scanner for confocal endomicroscopy.

Based on an advanced silicon optical bench technology with integrated MOEMS (Micro-Opto-Electro-Mechanical-System) components, a piezo-driven fiber scanner for confocal microscopy has been developed. This highly-miniaturized technology allows integration into an endoscope with a total outer probe diameter of 2.5 mm. The system features a hydraulically-driven varifocal lens providing axial confocal scanning without any translational movement of components. The demonstrated resolutions are 1.7 μm laterally and 19 μm axially.

Advances in arthroscopy-indications and therapeutic applications.

Advances in optical technology, instrumentation and implants now enable arthroscopic surgery to be performed on all large joints and most small joints of the limbs. Arthroscopic techniques are usually a development of surgical procedures previously performed through a large open incision, although the critical element of each procedure (for example removal of a torn meniscus) usually remains unchanged. The smaller size of incisions and reduction in tissue damage associated with arthroscopic surgery can reduce morbidity and complications. Therapeutic arthroscopy now encompasses excision, reconstruction and replacement of damaged or abnormal tissue. Improvements in the accuracy of MRI, CT and high-definition ultrasonography have limited the use of diagnostic arthroscopy to rare indications, but in the past 10 years the rates of some arthroscopic surgeries have increased by over 7-fold. Considerable variation in the type and utilization of arthroscopic procedures exists in practice, partly explained by the slow diffusion of new techniques and technology, but also by differences in clinician and patient beliefs and expectations. This Review reflects on both the success of arthroscopy and the general lack of evidence-based assessment of the efficacy and cost-effectiveness of arthroscopic procedures-a clear sign that more clinical trials in this field are required.

The BRAIN Initiative.

What is the first association that comes to mind when you hear “fiber optics”? Connecting one side of the Atlantic Ocean to the other, or high-definition television? For sure, it would not be manipulation of neuronal firing … unless you are a neuroscientist. While neuroscience has relied on optics to power discovery and advancement from the beginning of time, brain imaging remains an exotic application in mainstream optics and photonics. The Presidential BRAIN Initiative that launched in April of 2013 targets this disconnect by encouraging “hard core” technology experts to step up to the neuroscience quest. The goal of the Initiative is to develop new technologies driven by the needs of basic and translational neuroscience—easy to say, but difficult to do. The first challenge for the technology expert is to understand the needs of the endpoint application; for the neuroscientist, the challenge is to keep up with the rapidly developing technology and recognize its strengths and limitations. Generally speaking, brain tissue is an unfriendly environment for optics. Light is scattered by microscopic structures with different refractive indices and absorbed by natural chromophores. Red blood cells fly through capillaries, scattering and absorbing light along the way. The brain moves (slightly but noticeably on a microscopic scale) with respiration and heartbeat beyond what can be corrected for by rigid body registration. Furthermore, the duration of an action potential is only 1–2 ms, which imposes stringent constraints on the acquisition speed required for measurements of brain activity. In addition, brain tissue is sensitive to heating and photodynamic damage, placing limits on photon flux. Despite these limitations, consider this: arguably the most significant breakthroughs in neuroscience have been powered by advancements in optical technology, from the discovery of synaptic junctions by the father of modern neuroscience Ramon Y. Cajal in the 1880s, to contemporary advances in cell- and system-level neuroscience through utilization of two-photon microscopy, optogenetics, and superresolution microscopy. The BRAIN Initiative seeks to accelerate these efforts by scaling up the development of existing tools and encouraging exploration of new technological concepts to dramatically advance our understanding of how the brain works. Our first issue of Neurophotonics is published on the upswing of the initiative with a dedicated special section featuring a spectrum of papers on optical tools for measurement and manipulation of the brain’s neuronal, metabolic, and hemodynamic activity. This wide scope reflects the breadth of the arena and underscores collaborative opportunities for optics and photonics for targeted technology development rooted in the forefront of neuroscience research. In short, advances in the brain sciences require the attention of strong technology experts. The BRAIN Initiative has already succeeded in increasing the visibility of this seemingly exotic application within the optical community. The next step is to provide a path for a long-term multidisciplinary relationship enabling comprehensive technological developments emerging from proof of concept studies and leading to broad adoption by basic and clinical neuroscientists. Somewhere along this path, the brain application will become a little less exotic. However, the excitement will only grow as application-driven technology and technology-powered neuroscience evolve in a continual dialog.

Preface to Special Topic: Selected Papers from the Advances in Microfluidics and Nanofluidics 2014 Conference in Honor of Professor Hsueh-Chia Chang's 60th Birthday.

Preface to Special Topic: Selected Papers from the Advances in Microfluidics and Nanofluidics 2014 Conference in Honor of Professor Hsueh-Chia Chang's 60th Birthday.

Modern technologies for creating systems of optical and physical measurements of gas-dynamic fields with sizes up to 1000 mm

Basic technologies used to develop shadowgraphs, interference devices, and schlieren systems of the first and second generations failed to solve some problems of modern gas-dynamic experiments, first of all, creation of comparatively inexpensive and compact systems for optical and physical measurements of gas-dynamic fields (visualization fields) with sizes of 800–1000 mm and more. The demand for unique optical systems for wind tunnels and ballistic ranges is expected to increase in the near future: it is only these tools that can ensure adequate experimental investigations of flows around airplane, helicopter, future flying vehicle, car, and missile models whose scales are close to real ones. (In wind tunnels, the gas flow impinges onto a motionless model, e.g., of a flying vehicle; aeroballistic ranges allow direct modeling of the motion of examined bodies.) New capabilities of optical methods of gas flow research are implemented: a posteriori investigation of wave fields deformed after passing through the gas flow, increasing the sensitivity of optical measurements by one or two orders of magnitude, and manyfold increase in the amount of information obtained in a complex gas-dynamic experiment. Advanced optical technologies are used to solve these problems.

WDM Recirculation Buffer-Based Optical Fabric for Scalable Cloud Computing

Optical packet switching is the next-generation disruptive technology for massive cloud data centers. All-optical routers, supporting wavelength parallelism, accelerate the execution of applications and facilitate server virtualization. Despite the recent advances in optical technologies, the greatest challenge in the realization of optical routers is the lack of a mature solution for buffering optical signals. Fiber delay lines (FDLs) have been proposed to emulate electronic buffering by delaying contending optical packets for a fixed amount of time. However, the practical limitation on the number of FDLs in a router requires its ports to be run at low utilization, sacrificing a significant portion of network capacity. In this paper, we introduce a novel modular router architecture based on wavelength-division multiplexed (WDM) recirculation buffers as a solution to the problem of limited buffering capacity. We propose a load-balancing scheduler to maximize throughput. Our mathematical analysis and Monte Carlo simulations show that the consolidation of optical buffers in WDM FDLs accompanied with internal load balancing leads to a virtually lossless router, resilient to data center traffic anomalies. The load balancing further minimizes the number of packet recirculations, leading to negligible queueing latency. Our design supports physical layer scalability and is amenable to large-scale optical integration.

Invited: Heterogeneously Integrated III-V on Silicon Lasers

Silicon photonics has generated an outstanding interest for optical telecommunications and inter/intra-chip interconnects in microelectronic systems. This platform can address a wide range of applications from very short distance data communication to long haul optical transmission.Recent research has focused on the realization of silicon optoelectronic integrated devices using large scale, low-cost, and highly accurate CMOS technology. While silicon is now considered as the material of choice for passive optical components due to its low-loss beyond 1.1 µm and high-index-contrast with its native oxide, it is however a very poor light-emitting material. Today, practical Si-based light sources are still missing, despite the demonstration of an electrically pumped germanium laser.Silicon-based compounds are commonly used in commercial optical waveguide devices for applications such as passive optical interconnects and biomedical sensors. However, the integration of lasers together with Si integrated photonics-electronic circuits has proved to be much more challenging. The complexity lies in the fact that silicon is a poor light-emitting material due to its indirect energy bandgap. In addition, the direct growth of standard III-V materials on Si substrates is still a major obstacle because of the mismatch in lattice constants and in thermal expansion coefficients. Although light emission from silicon is not straightforward, the development of an efficient electrically pumped laser is essential to make silicon the material of choice for monolithic optoelectronic integration.A different way consists in coupling laser beams emerging from III-V heterostructures to silicon waveguides. This so-called hybrid integration can be done using different techniques like flip-chip bonding [1] or self-assembly [2]. Both approaches present the disadvantage of requiring submicron precision alignment to enable efficient coupling between lasers and silicon waveguides. Even if the cost of a silicon photonic circuit is generally low, aligning precisely a laser chip to a planar photonic circuit is quite expensive, time consuming and unsuitable for high-volume fabrication.A particularly promising approach instead is based on molecular bonding of III-V materials on top of a patterned Si-on-Insulator (SOI) substrate. This can be performed at the die or wafer level, depending on the application needs. Then, hybrid Si/III-V lasers are realized following a collective fabrication procedure, enabling complex photonic integrated systems onto the silicon platform [3]. Using this technology, Fabry–Pérot, racetrack, distributed feedback and Bragg reflectors lasers were demonstrated [4-5].In this communication, we describe the hybrid platform and we present the recent advances on III-V/Si lasers and transmitters. References K. Kato et al., IEEE J. Sel. Tops. Quantum Electron, 6, 4-13 (2000).J. Sasaki et al., IEEE Transactions on Advanced Packaging, 24, 569-575 (2001).J.M. Fedeli et al., Advances in Optical Technologies, 2008, 412518 (2008).B. Ben Bakir et al., Opt. Exp., vol. 19, no. 11, pp. 10317–10325 (2011).A. Descos et al. Eur. Conf. Opt. Commun., Th.1.B.2, pp. 687-689, London, U.K. (2013).

Wearable Photoplethysmographic Sensors—Past and Present

Photoplethysmography (PPG) technology has been used to develop small, wearable, pulse rate sensors. These devices, consisting of infrared light-emitting diodes (LEDs) and photodetectors, offer a simple, reliable, low-cost means of monitoring the pulse rate noninvasively. Recent advances in optical technology have facilitated the use of high-intensity green LEDs for PPG, increasing the adoption of this measurement technique. In this review, we briefly present the history of PPG and recent developments in wearable pulse rate sensors with green LEDs. The application of wearable pulse rate monitors is discussed.

Enhanced Electro-Optic Modulation Performance in Optical Buffers by Slowing Light in Optimized Photonic Crystal Slab Structures

Slow light holds the key to advanced optical bu ering and time-domain optical signal processing technologies. Photonic crystal based optical bu ers are particularly attractive due to their nanoscale size, room temperature operation, and enhanced eld dependent nonlinear response associated with the presence of slow light. In this study, the slow light and electro-optic modulation characteristics of a line-defect Si photonic crystal slab with triangular arrangement of holes lled with an electro-optic polymer (n = 1.6) are investigated by three-dimensional plane-wave expansion and nite-di erence time-domain methods. The rst rows adjacent to the line-defect are shifted gradually in the direction of light propagation and a slow light region with a high group index below the light-line is obtained for a shifting amount between 0.22a and 0.27a. For the photonic crystal con guration with 0.22a shifted rows, under modulated voltage change, the average group index is found to be decreasing with an increase in the bandwidth. The results show that the low group velocity supports a large delay time in a small modulated voltage variation. A linear change of group index with modulated voltage is obtained and the modulation sensitivity of central wavelength is obtained as 9.45 nm/V for a delay line length of 0.5 mm. Almost the same bu er capacity and bit length are found which provides the control of delay time exibly while keeping the bu er capacity and the bit length almost unchanged.

Advanced wireless and optical technologies for small-cell mobile backhaul with dynamic software-defined management

This article discusses novel wireless and optical technologies to address the radical new challenges of small cell mobile backhaul (MBH). Specifically, we examine 60 GHz and 70-80 GHz millimeter-wave technologies for high-capacity last mile and pre-aggregation backhaul, and orthogonal frequency-division multiple access passive optical networks as the optical technology complement for enabling flexible cost-efficient hybrid backhaul coverage. Flexible high-capacity hybrid millimeter wave/optical MBH network operation is next verified via network simulations in the context of a demanding, urban small-cell backhaul application. Finally, a novel software defined networking tool called the backhaul resource manager is introduced for automated dynamic resource provisioning and capacity-aware path computation that improves fairness, network utilization and end-to-end user quality of experience. The introduction of the novel wireless, optical, and software-defined technologies thus has the potential to truly revolutionize the future MBH network.

Quantitative Fluorescence Spectroscopy in Turbid Media: A Practical Solution to the Problem of Scattering and Absorption

The presence of practically unavoidable scatterers and background absorbers in turbid media such as biological tissue or cell suspensions can significantly distort the shape and intensity of fluorescence spectra of fluorophores and, hence, greatly hinder the in situ quantitative determination of fluorophores in turbid media. In this contribution, a quantitative fluorescence model (QFM) was proposed to explicitly model the effects of the scattering and absorption on fluorescence measurements. On the basis of the proposed model, a calibration strategy was developed to remove the detrimental effects of scattering and absorption and, hence, realize accurate quantitative analysis of fluorophores in turbid media. A proof-of-concept model system, the determination of free Ca(2+) in turbid media using Fura-2, was utilized to evaluate the performance of the proposed method. Experimental results showed that QFM can provide quite precise concentration predictions for free Ca(2+) in turbid media with an average relative error of about 7%, probably the best results ever achieved for turbid media without the use of advanced optical technologies. QFM has not only good performance but also simplicity of implementation. It does not require characterization of the light scattering properties of turbid media, provided that the light scattering and absorption properties of the test samples are reasonably close to those of the calibration samples. QFM can be developed and extended in many application areas such as ratiometric fluorescent sensors for quantitative live cell imaging.

Place des nouvelles techniques endoscopiques pour l’évaluation de la dysplasie sur endobrachyoesophage : quel intérêt en pratique ?

Recent technological advances in optics, computer-aided analysis, and miniaturization have allowed for the development of virtual chromoendoscopy and confocal laser endomicroscopy (CLE). CLE is based on the use of either a confocal scanning microscope integrated into a conventional flexible endoscope (eCLE or endoscopebased CLE) or trans-endoscopic probes (pCLE or probebased CLE). Both virtual chromoendoscopic techniques and CLE have enabled endoscopists to better characterize the gastrointestinal mucosa during endoscopy, and it has stimulated significant interest in the application of these techniques in clinical gastroenterology. This review aims to evaluate the current data on the technical aspects and the utility of these new technologies in Barrett’s esophagus.