Multiwavelength Transmission Research Articles

Reagentless Bacterial Identification Using a Combination of Multiwavelength Transmission and Angular Scattering Spectroscopy

Optics based technologies are being advanced by many diagnostic companies around the globe. This resurgence is being driven by several factors including novel materials, enhanced computer power, nonlinear optics, and advances in algorithmic and statistical analysis. This study expands on a previous paper that evaluated the capability of a reagent-free optical profiling platform technology that used multiwavelength transmission spectroscopy to identify bacterial pathogens from pure culture. This study combines multiwavelength angular scattering with transmission based analysis into a single algorithm that will identify bacterial pathogens. Six predominant organisms,S. aureus, E. coli,K. pneumoniaeandP. aeruginosa,E. faecalis,and coagulase negativeStaphylococcus, were analyzed from a total of 753 clinical isolates received from three large community hospital systems. The bacterial identification method used for comparison in this study was the Vitek-2 (bioMerieux) which utilizes a biochemically based identification system. All of the clinical isolates received were blinded as to their identification until completion of the optical analysis. Sensitivities ranged from 87.7 to 94.6% with specificities ranging from 97.2 to 99.9% indicating that optical profiling is a powerful and exciting new technology that could be developed for the rapid identification of pathogens without the use of chemical reagents.

Characterization of red blood cells with multiwavelength transmission spectroscopy.

Multiwavelength transmission (MWT) spectroscopy was applied to the investigation of the morphological parameters and composition of red blood cells (RBCs). The MWT spectra were quantitatively analyzed with a Mie theory based interpretation model modified to incorporate the effects of the nonsphericity and orientation of RBCs. The MWT spectra of the healthy and anemic samples were investigated for the RBC indices in open and blinded studies. When MWT performance was evaluated against a standard reference system, very good agreement between two methods, with R 2 > 0.85 for all indices studied, was demonstrated. The RBC morphological parameters were used to characterize three types of anemia and to draw an association between RBC morphology and anemia severity. The MWT spectra of RBCs infected with malaria parasite Plasmodium falciparum at different life cycle stages were analyzed for RBC morphological parameters. The changes in the RBC volume, surface area, aspect ratio, and hemoglobin composition were used to trace the morphological and compositional alterations in the infected RBCs occurring with parasites' development and to provide insights into parasite-host interactions. The MWT method was shown to be reliable for determination of the RBC morphological parameters and to be valuable for identification of the RBC pathologic changes and disease states.

Sub-THz Sensor Array With Embedded Signal Processing in 90 nm CMOS Technology

The architecture and the operation of a sub-THz sensor array are presented, which have been implemented in standard 90 nm CMOS technology. The integrated sensor array is arranged around of 12 silicon field effect plasma wave detectors with integrated planar antennas. The received signals are further processed by pre-amplifiers, analog to digital converters, and a time shared digital domain lock-in amplifier. The system automatically locks to external modulation and provides standard digital streaming output. Instead of building a uniform array, seven different antenna types with various polarization properties (horizontal and vertical linear; left and right handed circular polarization) and spectral responsivity have been integrated. The sensors altogether provide broadband response from 0.25 to 0.75 THz. The peak amplified responsivity of the sensors is 185 kV/W at 365 GHz and at the detectivity maximum, the noise equivalent power (NEP) is near to 40 pW/√Hz. Under nonzero drain current, the peak sensitivity rises above 1.2 MV/W with a moderate NEP ~ 200 pW/ Hz at 50 nA source-drain current. Application example is provided as a multi-wavelength transmission imaging case study.

Multiwavelength Transmission Spectroscopy Revisited for the Characterization of the Protein and Polystyrene Nanoparticle Mixtures

Multiwavelength Transmission (MWT) UV-Vis-NIR spectroscopy, an effective technique often underutilized for the characterization of processes involving particulates, such as protein aggregation, is systematically explored using bovine serum albumin and a set of NIST-traceable particle size (PS) standards having certified particle diameters over the nominal size range of 30 to 100 nm. The PS standards are used as surrogates for protein aggregates and other contaminants such as oils and microbubbles. Therefore, the standards can be used to quantitatively modify the optical properties of protein solutions and thus observe the effect of the presence of aggregates and other particulates on their wavelength-dependent transmission spectra. The experimental results demonstrate that the changes induced in the optical density spectra of proteins due to the presence of PS particles are detectable and consistent with the expectations set by light scattering theory. It is demonstrated that the size and relative concentrations of the particle populations present in the protein samples can be quantified. Because of the considerable dynamic range of MWT UV-Vis-NIR spectroscopy for particle analysis and its real-time measurement capabilities, this type of spectroscopy can be effectively used for the characterization of protein aggregates and for the continuous real-time monitoring of aggregation processes and for the identification and quantification of contaminants in protein-based products.

Multiwavelength Transmission Spectroscopy Revisited for the Characterization of the Protein and Polystyrene Nanoparticle Interactions

Multiwavelength transmission ultraviolet-visible-near-infrared (UV-Vis-NIR) spectroscopy is an effective technique that has not yet been fully exploited for the characterization of products of protein and particle interactions. Here, it is explored by using bovine serum albumin and National Institute of Standards and Technology-traceable particle size standard having a nominal diameter of 20 nm. Adsorption of bovine serum albumin to the particles is quantitatively ascertained through its effect on the wavelength-dependent transmission spectra of protein and particle mixtures. The experimental results demonstrate that the changes induced in the transmission spectra of protein and particle mixtures because of protein adsorption on particles are detectable and consistent with the expectations set by the light-scattering theory. The size, structure, composition, and relative concentrations of the particle populations present in the protein-particle mixtures can be quantified. Given the considerable dynamic range of multiwavelength transmission UV-Vis-NIR spectroscopy for particle analysis and its real-time measurement capabilities, this type of spectroscopy can be effectively used for the characterization of the products of protein-particle interaction and for the continuous real-time monitoring of interaction processes.

Performance Analysis of Multi-Wavelength Transmission Scanner for Polarized NIR Light

A system for small-object imaging, comprising a multiple-wavelength scanner for Near Infra-Red (NIR) light is under development in the Laboratory of Radiopharmaceuticals and Molecular Imaging (LRMI) at the National Laboratories of Legnaro, INFN, Italy. The System performs scanning of biological objects using NIR light in the interval of 900nm − 1700nm. The scanned region is a rectangular with dimensions of 50mm × 80mm and is performed by consecutive positioning of InGaAs linear image sensor sliding close to the scanned object. The scanning is carried out in two different modes. The first mode is performed in transmitted linearly polarized NIR light using a set of five light emitting diodes with fixed wavelengths. The process of scanning is realized by a consecutive positioning of the NIR sensor and signal acquisition at the corresponding position. In the second scanning mode the fluorescence emission of nanoparticles such as single-walled carbon nanotubes (SWCNTs), administered in the imaged object, is excited by NIR lasers with different wavelengths. Spatial resolution of the system for transmitted linearly polarized NIR at five fixed wavelengths has been determined. Polarimetric measurements of some optically active sugars such as fructose and lactose were conducted at some fixed wavelengths in the range of 900–1200nm. The system sensitivity with respect to the concentrations of these agents has been estimated.

Multi-Wavelength Transmission Spectroscopy Revisited for Micron and Submicron Particle Characterization

Multi-wavelength transmission (MWT) ultraviolet-visible-near-infrared (UV-Vis-NIR) spectroscopy, a technique underappreciated for particle characterization, is systematically explored using a set of NIST traceable standards over the nominal size range of 20 to 20,000 nm. Experimental results demonstrate that the particle size distributions obtained from MWT spectral data are in excellent agreement with the values reported by the manufacturer. In addition, it is shown that quantitative information on the particle concentration can be obtained--which is not currently accessible from commercially available light scattering instrumentation. The results validate that MWT UV-Vis-NIR spectroscopy has a considerable dynamic range for particle size measurements and offers significant advantages over other particle characterization techniques. Among these are the simplicity of the instrumentation and the measurements and the wealth of quantitative information contained in the MWT spectra. Most importantly, with standardized measurement protocols and standardized spectrometer configurations, MWT measurements can be used to provide the user and the manufacturer of particles with traceable data (i.e., the spectra and the quantitative analysis) for quality assurance.

Reagent-free bacterial identification using multivariate analysis of transmission spectra

The identification of bacterial pathogens from culture is critical to the proper administration of antibiotics and patient treatment. Many of the tests currently used in the clinical microbiology laboratory for bacterial identification today can be highly sensitive and specific; however, they have the additional burdens of complexity, cost, and the need for specialized reagents. We present an innovative, reagent-free method for the identification of pathogens from culture. A clinical study has been initiated to evaluate the sensitivity and specificity of this approach. Multiwavelength transmission spectra were generated from a set of clinical isolates including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. Spectra of an initial training set of these target organisms were used to create identification models representing the spectral variability of each species using multivariate statistical techniques. Next, the spectra of the blinded isolates of targeted species were identified using the model achieving >94% sensitivity and >98% specificity, with 100% accuracy for P. aeruginosa and S. aureus. The results from this on-going clinical study indicate this approach is a powerful and exciting technique for identification of pathogens. The menu of models is being expanded to include other bacterial genera and species of clinical significance.

Multi-Wavelength Transmission of Hollow-Core Bragg Fiber With Modified Binary One-Dimensional Photonic Crystal Cladding

To realize midinfrared multi-wavelength transmission within one octave, the modified binary one dimensional photonic crystal (MB-1DPC) is introduced to the hollow core Bragg fiber (HC-BF) as its cladding in this paper. Theoretical analysis shows that the MB-1DPC could provide wider higher-order PBGs than the B-1DPC; hence, the HC-BF with MB-1DPC cladding is prefer to realize multi-wavelength transmission within one octave by two adjacent higher-order PBGs. A HC-BF sample with MB-1DPC cladding was fabricated and measured. The fabricated fiber sample has two low loss transmission bands around 2137 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and 3016 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , with transmission losses of 3.50 dB/m and 3.79 dB/m, respectively. The multi-wavelength transmission within one octave of the HC-BF with MB-1DPC cladding has great potential in midinfrared multi-wavelength applications, such as multi-species gas sensing and infrared gas lasers.

High Speed Quantum Key Distribution System

Quantum key distribution (QKD) systems can generate unconditionally secure common keys between remote users. Improvements of QKD performance, particularly in key generation rate, have been required to meet current network traffic. A high-speed QKD system should be equipped with low-loss receivers with high visibility, highly efficient photon detectors with small dark count probability. A solution to these issues is to employ planar lightwave circuit (PLC) interferometers, single photon detection circuits and modules, together with multi-wavelength channels transmission using wavelength division multiplexing (WDM) technique.

Multiwavelength Transmission Microcavity in SOI Planar Ridge Waveguides

A novel waveguide-based 1-D photonic crystal (PhC) microcavity that simultaneously transmits light within the 1310- and 1550-nm wavelength telecommunications bands has been realized. A novel semianalytical model based on wave-vector diagrams was developed to enable rapid optimization of the 1-D PhC with complex periodicity to be etched into an SOI ridge waveguide. Measurements of the multiwavelength transmission characteristics of the resulting complex PhC microcavity revealed transmission peaks at 1321 and 1562 nm with nearly equal transmittivity that is close to the design specification.

Spectroscopy as a Tool for Characterization of Monomer Emulsions

The properties of the emulsions can be described by the droplet size distribution, which gives a statistical inventory of the dispersed phase fragmentation. This research reports measurements of droplet size distribution from multiwavelength transmission data and estimated of droplet size from electron microscope/osmium tetroxide technique. The quantitative interpretation of the transmission spectrum is performed in the spectral range (300–820 nm) leading to reliable estimated of droplet size populations in the range of 1–20 µm as function of the monomer concentration. The measurements reported are fast, highly reproducible and potential applicable to emulsification and polymerization processes. Abbreviations: Au absorbance units; UV‐vis ultraviolet‐visible; CMC, critical micellar concentration; Cm, monomer concentration calculated from dilution process; De, monomer concentration corresponding to electron microscope measurements; x¯, mean of the sample; s, standard deviation of the sample; DSD, droplet size distribution; PSD, particle size distribution.

Integrated optical 2 /spl times/ 2 switch for wavelength multiplexed interconnects

A highly compact integrated optical switch is proposed and demonstrated for broadband optical switching applications. Routing of 8 /spl times/ 10 Gb/s data channels is demonstrated using a low-cost 1250-Mb/s control scheme. The advantages of lossless operation, broad optical bandwidth, and nanosecond switching times are leveraged. Multichannel wavelength is exploited for reduced latency, enhanced capacity, and functionality, while retaining compatibility with existing off-the-shelf electronics and transceiver technology. The requirements for optical header processing, wavelength translation, and optical buffering are avoided. Low-penalty multiwavelength transmission is demonstrated for a highly compact sub-mm/sup 2/ amplifying 2 /spl times/ 2 switch. Pattern dependent gain and amplified spontaneous emission are minimized to facilitate 0.0-0.4 dB penalty. Mitigation techniques compatible with the architecture are deployed to reduce the penalty under adverse operating conditions. Control schemes are proposed and demonstrated to facilitate 8 /spl times/ 10 Gb/s optically switched networking.

Stability of Emulsions from Multiwavelength Transmission Measurements

Droplet populations are generated from the dynamic equilibrium between the breakup and coalescence phenomena occurring during the emulsification process. Adequate estimation of the droplet size and droplet size distribution is important, not only because they are related to the manufacturing process but also because the droplet size distribution provides information of the properties of the dispersed phase and the stability of the emulsions. This paper reports on a novel spectroscopy method that provides quantitative information for the assessment of the stability of liquid−liquid emulsions. The quantitative criterion is based on measurements of droplet populations as a function of the dispersed phase concentration. This technique is applied to fresh and aged emulsions of saturated hydrocarbons and monomers. The method reported for evaluation of the stability of emulsions is easy, inexpensive, and highly reproducible.

Multichannel soliton transmission and pulse shepherding in bit-parallel-wavelength optical fiber links

We study basic principles of the bit-parallel-wavelength (BPW) pulse transmission in multichannel single-mode optical fiber links for high-performance computer networks. We develop a theory of the pulse shepherding effect that allows simultaneous propagation of pulses in parallel bit slots by binding them into a multicomponent BPW soliton. We describe families of the BPW solitons and bifurcation cascades in a system of N incoherently coupled nonlinear Schrodinger equations that model the multichannel multiwavelength transmission in a single-mode optical fiber. We demonstrate high robustness of the composite BPW solitons, due to their underlying linear stability, to a moderate pulse walkoff.

Chaotic antiphase dynamics and synchronization in multimode semiconductor lasers

The dynamics of chaotic multimode semiconductor lasers is currently of considerable interest from the viewpoints of both fundamental physics and applications. Experimental observations and numerical simulations have been reported which show that multimode dynamics can play a significant role in a variety of complex dynamical phenomena, including low-frequency fluctuations ~LFF! and high-frequency chaotic oscillations @1‐6 #. Also, the synchronization of multimode dynamics in lasers has been considered as a mechanism for multiwavelength transmission of encoded data @7‐9#. A key issue in the behavior of multimode lasers is how the oscillations of different modes are related to each other. One general behavior that has been observed in multimode lasers is antiphase dynamics @10‐17#. Antiphase is a property related to coherence of the phases of the oscillations of the mode intensities rather than the optical phases. Alternating pulsations in two modes due to mode coupling is a simple example of antiphase dynamics. Antiphase dynamics have been shown to occur in the relaxation in a multimode class-B laser with cross saturation, where the lower-frequency components of oscillation of different longtitudinal modes cancel each other completely, so the total laser intensity oscillates with just a single oscillation frequency, resembling the relaxation of a single-mode laser @12,13#. Antiphase dynamics of multilongitudinal modes have been experimentally observed in various laser systems, including microchip lasers @12#, solid-state lasers @14,15#, fiber lasers @16#, and CO2 lasers @17#.

Continuously tunable multi-wavelength transmission filter based on a stabilised fibre-optic interferometer

We report the first successful demonstration, to our knowledge, of a continuously tunable multi-wavelength transmission filter based on environmentally stabilised fibre-optic Mach–Zehnder interferometer. The tunable scheme was achieved with a fine wavelength control through operating temperature adjustment of 1.3-μm laser diode used as light source for the stabilisation scheme. The transmission wavelength of the filter varied linearly with respect to the wavelength change of the stabilisation light source. The overall tuning range and the tuning sensitivity of the transmission wavelength of the tunable filter have been observed to be mainly dependent on those of the stabilisation light source itself.

Grating-assisted Mach-Zehnder OADM using photosensitive-cladding fibre for cladding mode coupling reduction

The realisation and systems performance of an optical add drop multiplexer (OADM) based on a grating-assisted Mach-Zehnder interferometer imprinted on photosensitive-cladding fibre are reported. This component provides low short wavelength losses, a high return loss at the input port, low chromatic dispersion and low PMD. A thorough characterisation is presented of the device and its system performance for multiwavelength transmission at 10 Gbit/s per channel, showing compatibility with 50 GHz grid dense WDM systems.

Multiwavelength Transmission of 980 nm-Pumped Erbium-doped Fiber Amplifier Cascaded Chain

Multiwavelength propagation of 980-nm-pumped EDFAs cascade based on an intrinsic gain-equalized method is investigated. We find that suppression of 1.53 μm amplified spontaneous emission power is an important issue to obtain small inter-channel power variations and high channel signal-to-noise ratios. Excellent system performance (negligible system penalty) of the 980-nm-pumped six-EDFA- cascede transmission was confirmed by means of a four-WDM-channel 365-km transmission experiment at 2.5 Gbit/s.

Optimum gain-equalised configuration of wideband erbium-doped fibre amplifier using inter-stage samarium-doped fibre and midway isolator

The optimum gain-equalised configuration for the erbium-doped fibre amplifier (EDFA) using a samarium-doped fibre (SDF) is investigated. The dual-pumping scheme with inter-stage SDF and midway isolator was found to be the optimum scheme for obtaining flattened high spectral gain with variation of ≤ ±0.7 dB and with a low noise figure of ≤ 5.6 dB within the 1530–1560 nm range. This amplifier is suitable for multiwavelength transmission systems containing EDFA cascades.