Optical Taper Research Articles

Design, Characterization, and Modeling for a Modular High-Resolution Solid-State X-Ray Image Intensifier (SSXII)

A high resolution x-ray imaging system designated the solid state x-ray image intensifier (SSXII) is being developed as a potential replacement of conventional lower-resolution x-ray detectors for neurovascular interventions. The SSXII consists of a CsI(Tl) phosphor to convert x-rays to light, a fiber optic taper to extend the field-of-view and to couple the phosphor to an Electron-Multiplying CCD (EMCCD) which has a built-in gain to boost the signal above the read-out noise floor. A parallel cascade linear-system model is explored and applied to quantitatively analyze the signal and noise transfer at each stage, and optimize the detector performance. The modulation transfer function (MTF), detective quantum efficiency (DQE) and frequency dependent instrumentation noise equivalent exposure (INEE) can be obtained from the theoretical model and experimental measurement. Agreement of these results validates the effectiveness of the model. Finally, compared with the traditional flat-panel detector (FPD), the SSXII exhibits better performance with higher spatial resolution, higher DQE and lower INEE.

Triple and Double Photons Absorption Process and Down-Conversion Laser Emitting Investigation of Er-Ion Doped Microsphere

We report a readily and cheap method to build taper optical fiber-Er3+ doped microsphere platform to investigate upconversion fluorescence emission and down-conversion laser oscillation with low threshold pump power. We demonstrate to dope Er3+ into silica microsphere surface by dipping a single-taper optical fiber into a certain concentration of erbium nitrate solution (Er(NO3)) , then dry it and use the electrical-arc of the optical fiber splicer to melt the tip of taper fiber to form the Er3+-doped silica microsphere due to surface tension induced. We also present a HF acid etching setup to fabricate low loss biconical optical taper fibers. We demonstrate the Er3+ doped silica microsphere triple photons and dual photons absorption process of up-conversion fluorescence emission and down-conversion laser oscillation spectra by using the optical tapered fiber to couple 976 nm/1534 nm pump light source.

Bioengineered bioluminescent magnetotactic bacteria as a powerful tool for chip-based whole-cell biosensors

This paper describes the generation of genetically engineered bioluminescent magnetotactic bacteria (BL-MTB) and their integration into a microfluidic analytical device to create a portable toxicity detection system. Magnetospirillum gryphiswaldense strain MSR-1 was bioengineered to constitutively express a red-emitting click beetle luciferase whose bioluminescent signal is directly proportional to bacterial viability. The magnetic properties of these bacteria have been exploited as "natural actuators" to transfer the cells in the chip from the reaction to the detection area, optimizing the chip's analytical performance. A robust and cost-effective biosensor for the evaluation of sample toxicity, named MAGNETOX, based on lens-free contact imaging detection, has been developed. A microfluidic chip has been fabricated using multilayered black and transparent polydimethyl siloxane (PDMS) in which BL-MTB are incubated for 30 min with the sample, then moved by microfluidics, trapped, and concentrated in detection chambers by an array of neodymium-iron-boron magnets. The chip is placed in contact with a cooled CCD via a fiber optic taper to perform quantitative bioluminescence imaging after addition of luciferin substrate. A model toxic compound (dimethyl sulfoxide, DMSO) and a bile acid (taurochenodeoxycholic acid, TCDCA) were used to investigate the analytical performance of the MAGNETOX. Incubation with DMSO and TCDCA drastically reduces the bioluminescent signal in a dose-related manner. The generation of bacteria that are both magnetic and bioluminescent combines the advantages of easy 2D cell handling with ultra sensitive detection, offering undoubted potential to develop cell-based biosensors integrated into microfluidic chips.

The Fabrication and Inspection of a Microball Made of Optical Fibre for Micro-Nano Coordinating Measuring Machine

The manufacture of micro-nano three-dimensional (3D) probe is a key factor for Micro-nano Coordinating Measuring Machine (Micro-nano CMM) to achieve the precise measurement. This paper proposes a method to fabricate a microball from an optical fibre using a fibre fusion splicer, which is used for Micro-nano CMM to measure miniature workpieces. Utilizing fused optical fibre tapering and choosing proper melting parameters, a microball with diameter of about 100μm and with roundness of less than 2μm could be fabricated. The offset distance between the microball centre and fibre stylus central line due to the gravity effect could be less than 1μm. This approach not only greatly reduces the time for the preparation of the probe, but also extends micro-nano CMM’s capability of measuring miniature workpieces.

光强局部选通成像器中光锥耦合技术研究

In order to distinguish details of the image under strong light,the optic taper is employed in the partially light-controlled imaging detector based liquid crystal,tender that the image is transferred from TFT-LCD(Thin Film Transistor-Liquid Crystal Display)to CCD(Charge-Coupled Device)in real time.Through theoretical analysis and calculation,the coupling efficiency with optical tapper to CCD is 14.24%,while,and the coupling efficiency with lens is 1.83%.MTF(modulation transfer function) of the system coupling with optical taper is 0.518 at Nyquist frequency,and the limit resolution is 34 lp/mm.The device produced with this method can distinguish details of the image under high illumination.It is better than the lens-coupled device significantly.The reasons that MTF drops in practical engineering is analyzed,and some methods solving the matter is put forward.

光强局部选通成像器中光锥耦合技术研究

光强局部选通成像器中光锥耦合技术研究

Selective polarization mode excitation in InGaAs/GaAs microtubes

We report on selective polarization mode excitation in InGaAs/GaAs rolled-up microtubes. The microtubes are fabricated by selectively releasing a coherently strained InGaAs/GaAs quantum dot layer from its host GaAs substrate. An optical fiber abrupt taper is used to pick up the microtube, while an adiabatically tapered optical fiber is used to couple light into the resonant optical modes of the microtube. By varying the polarization of the light in the adiabatically tapered fiber both transverse electric and transverse magnetic modes are observed in the microtube. We also show that the microtube can be used as a red (0.6 μm) to infrared light (1.5 μm) optical-optical modulator taking advantage of the thermal-optical effect.

Tunable Short Cavity 10-Gb/s 1550-nm DFB-Laser With Integrated Optical Amplifier and Taper

A novel tunable 1550-nm buried heterostructure (BH-) distributed feedback (DFB)-laser is presented consisting of a phase tuning section, a short cavity complex coupled DFB section, and an amplifier section with integrated optical taper. The device shows a narrow optical far-field, a high optical output power, up to 10-Gb/s direct modulation capability and a wavelength tuning range of several nanometers by varying the current in the phase section only.

Single rolled-up InGaAs/GaAs quantum dot microtubes integrated with silicon-on-insulator waveguides

We report on single rolled-up microtubes integrated with silicon-on-insulator waveguides. Microtubes with diameters of ~7 μm, wall thicknesses of ~250 nm, and lengths greater than 100 μm are fabricated by selectively releasing a coherently strained InGaAs/GaAs quantum dot layer from the handling GaAs substrate. The microtubes are then transferred from their host substrate to silicon-on-insulator waveguides by an optical fiber abrupt taper. The Q-factor of the waveguide coupled microtube is measured to be 1.5×10(5), the highest recorded for a semiconductor microtube cavity to date. The insertion loss and extinction ratio of the microtube are 1 dB and 34 dB respectively. By pumping the microtube with a 635 nm laser, the resonance wavelength is shifted by 0.7 nm. The integration of InGaAs/GaAs microtubes with silicon-on-insulator waveguides provides a simple, low loss, high extinction passive filter solution in the C+L band communication regime.

Portable Device Based on Chemiluminescence Lensless Imaging for Personalized Diagnostics through Multiplex Bioanalysis

A simple and versatile analytical device designed to perform, even simultaneously, different types of bioassays has been developed and optimized. A transparent microfluidics-based reaction chip, where analytes were quantitatively detected by means of biospecific reactions and chemiluminescence detection, was placed in contact with a thermoelectrically cooled CCD sensor through a fiber optic taper. Such a lensless contact imaging configuration combined adequate spatial resolution and high light collection efficiency within a small size portable device. The miniaturization of the reaction chamber ensured short analysis times (in the minutes range), while the use of chemiluminescence detection provided wide signal dynamic range and high detectability, down to attomole levels of protein and femtomole levels of nucleic acid analytes. A model hybrid panel test was realized by combining an enzyme assay for alkaline phosphatase activity, a nucleic acid hybridization assay for Parvovirus B19 DNA, and an immunoassay for horseradish peroxidase as a model antigen. The successful simultaneous quantification of the three targets demonstrated that a range of analytes, from enzymes to antigens, antibodies, and nucleic acids, can be measured in a single run, thus enabling the realization of a complete, personalized diagnostic panel test for early diagnosis of a given disease and patient follow-up.

Theoretic research on emergence angle of specialty solid coupled optical taper

The emergence angle of specialty solid coupled (SSC) optical taper is numerically studied by using ray-tracing method, which depends on the shape curve function. The relationships between the taper length, shape factor, large-end and small-end radii and the emergence angle are analyzed, respectively. The results show that the variation of small-end radius has great influence on the range of emergence angle for SSC optical taper. Therefore, given the shape curve function of the SSC optical taper, the emergence angle can be used for analyzing the transmission loss of SSC optical taper.

A portable bioluminescence engineered cell-based biosensor for on-site applications

We have developed a portable biosensing device based on genetically engineered bioluminescent (BL) cells. Cells were immobilized on a 4 × 3 multiwell cartridge using a new biocompatible matrix that preserved their vitality. Using a fiber optic taper, the cartridge was placed in direct contact with a cooled CCD sensor to image and quantify the BL signals. Yeast and bacterial cells were engineered to express recognition elements, whose interaction with the analyte led to luciferase expression, via reporter gene technology. Three different biosensors were developed. The first detects androgenic compounds using yeast cells carrying a green-emitting P. pyralis luciferase regulated by the human androgen receptor and a red mutant of the same species as internal vitality control. The second biosensor detects two classes of compounds (androgens and estrogens) using yeast strains engineered to express green-or red-emitting mutant firefly luciferases in response to androgens or estrogens, respectively. The third biosensor detects lactose analogue isopropyl β- d-1-thiogalactopyranoside using two E. coli strains. One strain exploits the lac operon as recognition element for the expression of P. pyralis luciferase. The other strain serves as a vitality control expressing Gaussia princeps luciferase, which requires a different luciferin substrate. The immobilized cells were stable for up to 1 month. The analytes could be detected at nanomolar levels with good precision and accuracy when the specific signal was corrected using the internal vitality control. This portable device can be used for on-site multiplexed bioassays for different compound classes.

Beam reception and data transmission performance analysis of optical taper used in a mobile wireless optical communication

Mobile wireless optical communication system was demonstrated experimentally by using a special solid coupling optical taper. The performance of special solid coupling optical taper and the data transmission performance with 240 Mbit/s were investigated on the rectilinear orbit between the mobile terminal and the fixed terminal. The experimental results shown that the scheme used in the mobile wireless optical communication system is reliable and quite simple, which could be widely used in future.

Acrylic and metal based Y-branch plastic optical fiber splitter with optical NOA63 polymer waveguide taper region

We proposed a simple low-cost acrylic and metal-based Y-branch plastic optical fiber (POF) splitter which utilizes a low cost optical polymer glue NOA63 as the main waveguiding medium at the waveguide taper region. The device is composed of three sections: an input POF waveguide, a middle waveguide taper region and output POF waveguides. A desktop high speed CNC engraver is utilized to produce the mold inserts used for the optical devices. Short POF fibers are inserted into the engraved slots at the input and output ports. UV curable optical polymer glue NOA63 is injected into the waveguide taper region and cured. The assembling is completed when the top plate is positioned to enclose the device structure and connecting screws are secured. Both POF splitters have an average insertion loss of 7.8 dB, coupling ratio of 55: 45 and 57: 43 for the acrylic and metal-based splitters respectively. The devices have excess loss of 4.82 and 4.73 dB for the acrylic and metal-based splitters respectively.

Near-field optical taper antennas fabricated with a highly replicable ac electrochemicaletching method

This paper describes a novel chemical etching method to fabricate high quality near-fieldoptical antennas—tapered metallic tips—from gold wire in a reproducible way foroptically probing a specimen on the nanoscale. A new type of an electrochemicalcell is introduced and different dc and ac etching regimes are studied in detail.The formation and dynamics of a meniscus around a gold wire immersed in anelectrolyte when supplying a square wave voltage are considered. We show that in situetching current kinetics allows one to improve a yield of tips with a well-definedgeometry up to 95% by filtering these on the basis of a cutoff current and a powerspectrum of etching current fluctuations. As a quantitative measure for estimating theyield we introduce a probability to find tips with curvature radii falling in therange of interest. Testing the tips for a plasmonic effect is implemented withtip-enhanced Raman spectroscopy and sub-wavelength imaging of a thin fullerene film.

A fiber-diffraction interferometer using a coherent fiber optic taper

We present a fiber-diffraction interferometer using a coherent fiber optic taper (FOT) for optical testing in an uncontrolled environment. We use a coherent FOT and a single-mode fiber (SMF) with a thermally expanded core. Part of the measurement wave coming from a test target is condensed through an FOT and spatially filtered from an SMF to be the reference wave. Vibration of the cavity between the target and the interferometer probe is common to both reference and measurement waves. Thus the interference fringe is stabilized in an optical way. Generation of the reference wave is stable even with the target movement. The focus shift of the input measurement wave is desensitized by a coherent FOT.

A high precision recipe for correcting images distorted by a tapered fiber optic

Images captured with a tapered fiber optic camera show significant spatial distortion mainly because the spatial orientation of the fiber bundles is not identical at each end of the taper. We present three different techniques for the automatic distortion correction of images acquired with a charge-coupled device (CCD) camera bonded to a tapered optical fiber. In this paper we report — (i) comparison of various methods for distortion correction (ii) extensive quantitative analysis of the techniques and (iii) experiments carried out using a high resolution fiber optic camera. A pinhole array was used to find control points in the distorted image space. These control points were then associated with their known true coordinates. To apply geometric correction, three different approaches were investigated — global polynomial fitting, local polynomial fitting and triangulated interpolation. Sub-pixel accuracy was achieved in all approaches, but the experimental results reveal that the triangulated interpolation gave the most satisfactory result for the distortion correction. The effect of proper alignment of the mask with the fiber optic taper (FOT) camera was also investigated. It was found that the overall dewarping error is minimal when the mask is almost parallel to the CCD.

Investigation of a shape curve function for a special solid coupled optical taper

For a special solid coupled optical taper, a differential equation of its shape curve is deduced using the curvature-shape matching relationship, and the closed-form solution of the equation can be acquired by its concrete initial curvature and shape boundary condition. Since the physical formation process in different tapering conditions can be described conveniently by the solution, the variation relationships among the taper length, shape factor, large-end radius, small-end radius, and shape function are analyzed. The results show that the theoretical simulation is basically in accordance with the experimental data and the errors are also given. Thus, given the shape factor parameters of the special solid coupled optical taper, the solution can be properly used to predict the taper shape curve for any taper length, large-end radius, and small-end radius.

MO‐E‐204C‐01: Radionuclide Imaging with a CCD‐Based, High‐Resolution X‐Ray Detector in Single Photon Counting Mode

Purpose: To demonstrate use of the high‐resolution Micro‐Angiographic Fluoroscopic (MAF) detector in single‐photon counting (SPC) mode for nuclear medicine imaging. Method and Materials: The MAF uses a CCD camera and fiber‐optic taper, has 1024 × 1024 pixels with effective pixel size of 35 microns and is capable of real‐time imaging. A 300 micron cesium iodide is coupled to a light image intensifier through a fiber optic taper. Large variable gain of the LII provides quantum‐limited operation with essentially no additive instrumentation noise and enables the MAF to operate in both energy‐integrating (EI) and the very‐sensitive low‐exposure SPC modes. To evaluate the MAF in SPC mode, a custom‐made phantom, with hot rods ranging from diameters 0.9mm to 2.3mm, filled with 1mCi of 125I was used as a test object. A medium‐energy, gamma‐camera collimator with 1‐mm diameter parallel holes was placed between the phantom and the MAF. Data was acquired at 20 fps. The collimator was used in two ways: (i) Stationary and (ii) Moving multiple times in random directions during data acquisition to blur the septal pattern with approximately the same number of counts detected per position. Each frame of the two sets was processed using two algorithms to localize events: (i) simple‐threshold and (ii) weighted‐centroid methods. The processed frames were added to give the final image. Results: (i) Stationary collimator: The image showed a grid‐like pattern corresponding to the septa walls of the collimator. All of the hot rods in the phantom can be identified, (ii) Moving collimator: The septal pattern is blurred out, and all of the rods can be clearly identified. Conclusion: The same MAF can be used in both nuclear‐medicine imaging and x‐ray imaging in SPC mode for dual‐mode imaging. Currently we are limited by collimator resolution for radionuclide imaging. Support from: NIH Grants R01EB002873 and R01EB008425.

WE-E-201C-06: The Next Generation Solid State X-Ray Image Intensifier (SSXII)

Purpose: We report on new advancements with a solid state x‐ray image intensifier (SSXII) to expand the field‐of‐view (FOV) and improve detector performance. Method and Materials: The SSXII is a new high‐resolution, high‐sensitivity radiographic and fluoroscopic imager based on electron‐multiplying CCDs (EMCCDs), which views a CsI:Tl phosphor through a fiber optic taper (FOT). The SSXII has demonstrated the capabilities to significantly improve upon the inherent limitations of current state‐of‐the‐art x‐ray image intensifiers and dynamic flat panel detectors(FPD), with superior performance in terms of MTF, instrumentation noise, and DQE. To expand the FOV, a modular array has been constructed. The EMCCD camera electronics have been designed to enable a 2 × 2 abuttable array configuration. The 27 mm center‐to‐center distance enables use of 3.4:1 magnification ratio FOTs, thereby providing a FOV of 5.44 × 5.44 cm (an increase in area of 290% over the initial single module prototype). Larger arrays can be constructed. Performance of this next generation SSXII was extrapolated based on measured MTFs and transmission efficiencies of the individual components that comprise the detector.Results: Calculations indicate an averaged improvement in the MTF of a factor of 1.2 across the higher spatial‐frequency range (5 to 10 cycles/mm). X‐ray sensitivities are expected to increase by 40% due to a reduction in the FOT magnification ratio (from 4:1 to 3.4:1). The instrumentation noise equivalent exposure (INEE) was calculated to decrease from 0.2 to 0.03 μR, which is two orders of magnitude lower than present FPDs. The DQE was determined to improve by an averaged factor of 2.2 from 5 to 10 cycles/mm. Conclusions: With an expanded FOV, the SSXII is a promising candidate to replace existing state‐of‐the‐art detectors, providing improved resolution, lower instrumentation noise, and better signal‐to‐noise ratio performance. (Support: NIH Grant RO1EB008425)