The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform

Abraham Katzir - One of the best experts on this subject based on the ideXlab platform.

  • Mid-Infrared Fiber-optic evanescent field spectroscopy for in situ monitoring of tetrahydrofuran hydrate formation and dissociation
    The Analyst, 2017
    Co-Authors: Matthias Schwenk, Abraham Katzir, Boris Mizaikoff
    Abstract:

    Tetrahydrofuran is a relevant auxiliary molecule when storing carbon dioxide or hydrocarbons as gas hydrates. The present study demonstrates the application of in situ mid-Infrared Fiber-optic evanescent field absorption spectroscopy for studying the formation and dissociation of THF hydrates. Thereby, the utility of this analytical technique for providing unique molecular-level insight even under harsh environmental conditions is evidenced.

  • Bonding surgical incisions using a temperature-controlled laser system based on a single Infrared Fiber
    Journal of biomedical optics, 2013
    Co-Authors: Ilan Gabay, Irina S. Barequet, David Varssano, Mordechai Rosner, Abraham Katzir
    Abstract:

    ABSTRACT. Although there has been great interest in laser heating for bonding of surgical incisions in tissues, it has not gained wide acceptance by surgeons. We argue that the main obstacle has been the lack of temperature control, which may lead to a weak bonding. We previously developed a laser bonding system based on two Infrared transmitting AgBrCl Fibers, one for laser heating and one for temperature control. In view of the inherent limitations of such systems observed in many animal experiments, we developed an improved system based on a single Infrared Fiber. Besides the decreased dimensions, this system offers many advantages over the two-Fiber system. It is less sensitive to accuracy of height and tilt of the Fiber distal tip above the tissue, ensuring more accurate heating that can potentially lead to stronger bonding with minimal thermal damage. The system is successfully tested in the soldering of 15 corneal incisions, ex vivo. Histopathology shows little thermal damage and good wound apposition. The average burst pressure is 100±30  mm Hg. These findings indicate the usefulness of the system for ophthalmic surgery as well as other surgical procedures, including endoscopic and robotic surgery.

  • CO2 Laser Welding of Corneal Cuts with Albumin Solder Using Radiometric Temperature Control
    Ophthalmic research, 2013
    Co-Authors: Eyal Strassmann, Abraham Katzir, Eitan Livny, Nino Loya, Noam Kariv, Avi Ravid, Dan D. Gaton
    Abstract:

    Purpose: To examine the efficacy and reproducibility of CO2 laser soldering of corneal cuts using real-time Infrared Fiber-optic radiometric control of

  • Mid-Infrared Fiber-optic attenuated total reflection spectroscopy of the solid-liquid phase transition of water.
    Applied spectroscopy, 2005
    Co-Authors: Arnon Millo, Yosef Raichlin, Abraham Katzir
    Abstract:

    Measurements of mid-Infrared (MIR) absorption spectra of water and heavy water were carried out by Fiber-optic evanescent wave spectroscopy, using silver halide (AgClBr) Infrared Fibers. Such measurements were performed for the first time on one sample, during the solid-liquid phase transition. From the variation of the spectra with temperature we found a new isosbestic point (at 3280 cm(-1) for H(2)O or at 2475 cm(-1) for D(2)O) and we identified five components of the O-H (O-D) stretch band. These phenomena have provided new information about the molecular structure of water.

  • Thermal imaging through Infrared Fiber/waveguides bundles
    Optical Fibers and Sensors for Medical Applications IV, 2004
    Co-Authors: Israel Gannot, Abraham Katzir, Alon Goren, Eran Rave, Veena Gopal, Gregory Revezin, James A. Harrington
    Abstract:

    Trans-endoscopic Infrared Imaging (IRI) relates the possibility to conduct IRI diagnosis of internal body surfaces under minimal invasiveness. It may also be utilized to control and to optimize the thermal interactions and the potential side effects during Minimally Invasive Surgeries (MIS). However, transferring the thermal images transendoscopically requires the usage of IR imaging bundles, which are neither yet mature nor commercially available. In our setup we have used two basic types of recently-developed imaging bundles: Ag/AgI-coated Hollow Glass Waveguide (HGW) bundles and Silver Halide (AgClBr) core-clad Fiber bundles. The optical setup system was consisted of IR optics (e.g. ZnSe lenses, reflective objectives) and a thermal IR camera. We have succeeded to image objects through the bundles, such as various shapes of electrically heated wires, ex-vivo biological phantoms (samples of porcine stomach) and in-vivo phantom models (mice) irradiated by CO2 laser. Measurements were conducted for both - static and dynamic object states.

Stuart D. Jackson - One of the best experts on this subject based on the ideXlab platform.

  • Erbium-doped mid-Infrared Fiber lasers
    Laser Technology for Defense and Security XV, 2019
    Co-Authors: Ori Henderson-sapir, Stuart D. Jackson, Andrew Malouf, Jesper Munch, Nathaniel Bawden, Elizaveta Klantsataya, Matthew R. Majewski, Hiraku Matsukuma, Shigeki Tokita, Sze Yun Set
    Abstract:

    The performance of mid-Infrared Fiber lasers operating on the 3.5 μm transition in erbium has improved significantly since the first demonstration that dual wavelength pumping allowed efficient operation. In this contribution, we will discuss the progress of Fiber lasers that operate on this transition with an emphasis on advances towards short pulse generation and wavelength agility. Mode-locked operation using saturable absorption is a robust means of achieving ultra-short pulse operation in the near Infrared but achieving this in the mid-Infrared has been elusive. We will also describe our characterization of the mid-Infrared performance of graphene, a material which has been very successfully applied to mode-locked pulse generation in the near Infrared.

  • Ultrafast mid-Infrared Fiber laser mode-locked using frequency-shifted feedback.
    Optics letters, 2019
    Co-Authors: Matthew R. Majewski, Robert I. Woodward, Stuart D. Jackson
    Abstract:

    We demonstrate ultrashort pulse generation from a fluoride Fiber laser co-doped with holmium and praseodymium. To date, the majority of work focused on short pulse generation from this class of Fiber laser has employed loss modulators in the cavity, both real and artificial. In this Letter, we alternatively employ a frequency shifting element: an acousto-optic modulator (AOM) in the cavity. This results in mode-locked output of sub-5 ps pulses with 10 nJ of energy at a center wavelength of 2.86 μm and a pulse repetition frequency of 30.1 MHz, equating to a peak power of 1.9 kW. Additional experimental investigation of the relationship between frequency shift and cavity round trip offer insight into the complex underlying dynamics. As a complementary mode-locking technique to conventional loss modulation, this method of pulse-formation may greatly expand the design flexibility of pulsed mid-Infrared Fiber lasers.

  • Swept-wavelength mid-Infrared Fiber laser for real-time ammonia gas sensing
    APL Photonics, 2019
    Co-Authors: Robert I. Woodward, Darren. D. Hudson, Matthew R. Majewski, Stuart D. Jackson
    Abstract:

    The mid-Infrared (mid-IR) spectral region holds great promise for new laser-based sensing technologies, based on measuring strong mid-IR molecular absorption features. Practical applications have been limited to date, however, by current low-brightness broadband mid-IR light sources and slow acquisition-time detection systems. Here, we report a new approach by developing a swept-wavelength mid-Infrared Fiber laser, exploiting the broad emission of dysprosium and using an acousto-optic tunable filter to achieve electronically controlled swept-wavelength operation from 2.89 to 3.25 {\mu}m (3070-3460 cm^-1). Ammonia (NH3) absorption spectroscopy is demonstrated using this swept source with a simple room-temperature single-pixel detector, with 0.3 nm resolution and 40 ms acquisition time. This creates new opportunities for real-time high-sensitivity remote sensing using simple, compact mid-IR Fiber-based technologies.

  • Generation of 70-fs pulses at 2.86 μm from a mid-Infrared Fiber laser.
    Optics letters, 2017
    Co-Authors: Robert I. Woodward, Darren. D. Hudson, Alexander Fuerbach, Stuart D. Jackson
    Abstract:

    We propose and demonstrate a simple route to few-optical-cycle pulse generation from a mid-Infrared Fiber laser through nonlinear compression of pulses from a holmium-doped Fiber oscillator using a short length of chalcogenide Fiber and a grating pair. Pulses from the oscillator with 265-fs duration at 2.86 μm are spectrally broadened through self-phase modulation in step-index As2S3 Fiber to 141-nm bandwidth and then re-compressed to 70 fs (7.3 optical cycles). These are the shortest pulses from a mid-Infrared Fiber system to date, and we note that our system is compact, robust, and uses only commercially available components. The scalability of this approach is also discussed, supported by numerical modeling.

  • Diode-pumped mid-Infrared Fiber laser with 50% slope efficiency
    Optica, 2017
    Co-Authors: Yigit Ozan Aydin, Stuart D. Jackson, Vincent Fortin, Frédéric Maes, Frédéric Jobin, Réal Vallée, Martin Bernier
    Abstract:

    Until now, the field of mid-Infrared Fiber laser research has been constrained by the limitation imposed by the Stokes efficiency limit. The conversion of high-power diode light emission operating at near-Infrared wavelengths into mid-Infrared light invariably results in the deposition of significant amounts of heat in the Fiber. This issue is compounded by the fact that mid-Infrared transmitting glasses are thermomechanically weak, which means scaling the output power has been a longstanding challenge. In this report, we show that by cascading the adjacent transitions of the erbium ion at 2.8 and 1.6 μm in combination with a low-loss fluoride Fiber, the slope efficiency for emission at 2.8 μm can reach 50%, thus exceeding the Stokes limit by 15%. We also show that by highly resonating the 1.6 μm transition, a highly non-resonant excited-state absorption process efficiently recycles the excitation back to the upper laser level of the mid-Infrared transition. This demonstration represents a significant advancement for the field that paves the way for future demonstrations that will exceed the 100 W power level.4 page(s

Darren. D. Hudson - One of the best experts on this subject based on the ideXlab platform.

  • Swept-wavelength mid-Infrared Fiber laser for real-time ammonia gas sensing
    APL Photonics, 2019
    Co-Authors: Robert I. Woodward, Darren. D. Hudson, Matthew R. Majewski, Stuart D. Jackson
    Abstract:

    The mid-Infrared (mid-IR) spectral region holds great promise for new laser-based sensing technologies, based on measuring strong mid-IR molecular absorption features. Practical applications have been limited to date, however, by current low-brightness broadband mid-IR light sources and slow acquisition-time detection systems. Here, we report a new approach by developing a swept-wavelength mid-Infrared Fiber laser, exploiting the broad emission of dysprosium and using an acousto-optic tunable filter to achieve electronically controlled swept-wavelength operation from 2.89 to 3.25 {\mu}m (3070-3460 cm^-1). Ammonia (NH3) absorption spectroscopy is demonstrated using this swept source with a simple room-temperature single-pixel detector, with 0.3 nm resolution and 40 ms acquisition time. This creates new opportunities for real-time high-sensitivity remote sensing using simple, compact mid-IR Fiber-based technologies.

  • Generation of 70-fs pulses at 2.86 μm from a mid-Infrared Fiber laser.
    Optics letters, 2017
    Co-Authors: Robert I. Woodward, Darren. D. Hudson, Alexander Fuerbach, Stuart D. Jackson
    Abstract:

    We propose and demonstrate a simple route to few-optical-cycle pulse generation from a mid-Infrared Fiber laser through nonlinear compression of pulses from a holmium-doped Fiber oscillator using a short length of chalcogenide Fiber and a grating pair. Pulses from the oscillator with 265-fs duration at 2.86 μm are spectrally broadened through self-phase modulation in step-index As2S3 Fiber to 141-nm bandwidth and then re-compressed to 70 fs (7.3 optical cycles). These are the shortest pulses from a mid-Infrared Fiber system to date, and we note that our system is compact, robust, and uses only commercially available components. The scalability of this approach is also discussed, supported by numerical modeling.

  • high power mid Infrared femtosecond Fiber laser in the water vapor transmission window
    Optica, 2016
    Co-Authors: Sergei Antipov, Darren. D. Hudson, Alexander Fuerbach, Stuart D. Jackson
    Abstract:

    The recent demonstrations of ultrafast mid-Infrared Fiber lasers emitting sub-picosecond pulses at 2.8 μm have created an exciting potential for a range of applications including mid-Infrared frequency combs and materials processing. So far, this new class of laser has been based on the I11/24-I13/24 transition in erbium-doped fluoride Fibers, which lies directly in a region of high water vapor absorption. This absorption has limited the achievable bandwidth, pulse duration, and peak power and poses a serious problem for transmission in free space. In this Letter, we present an ultrafast mid-Infrared Fiber laser that overcomes these limitations by using holmium as the gain medium. Holmium allows the central emission wavelength to shift to nearly 2.9 μm and avoid the strong water vapor lines. This laser, which represents the longest wavelength mode-locked Fiber laser, emits 7.6 nJ pulses at 180 fs duration, with a record peak power of 37 kW. At this power level, the laser surpasses many commercial free-space OPA systems and becomes attractive for laser surgery of human tissue, for industrial materials modification, and for driving broadband coherent supercontinuum in the mid-Infrared.

  • Ultrafast pulses from a mid-Infrared Fiber laser
    Optics Letters, 2015
    Co-Authors: Tomonori Hu, Stuart D. Jackson, Darren. D. Hudson
    Abstract:

    Ultrafast laser pulses at mid-Infrared wavelengths (2–20 μm) interact strongly with molecules due to the resonance with their vibration modes. This enables their application in frequency comb-based sensing and laser tissue surgery. Fiber lasers are ideal to achieve these pulses, as they are compact, stable, and efficient. We extend the performance of these lasers with the production of 6.4 kW at a wavelength of 2.8 μm with complete electric field retrieval using frequency-resolved optical gating techniques. Contrary to the problems associated with achieving a high average power, fluoride Fibers have now shown the capability of operating in the ultrafast, high-peak-power regime.

Bongsoo Lee - One of the best experts on this subject based on the ideXlab platform.

  • Development of a 2-channel embedded Infrared Fiber-optic temperature sensor using silver halide optical Fibers
    Sensors, 2011
    Co-Authors: Wook Jae Yoo, Jeong Ki Seo, Jinsoo Moon, Ki-tek Han, Jang-yeon Park, Kyoung Won Jang, Byung Gi Park, Bongsoo Lee
    Abstract:

    A 2-channel embedded Infrared Fiber-optic temperature sensor was fabricated using two identical silver halide optical Fibers for accurate thermometry without complicated calibration processes. In this study, we measured the output voltages of signal and reference probes according to temperature variation over a temperature range from 25 to 225 °C. To decide the temperature of the water, the difference between the amounts of Infrared radiation emitted from the two temperature sensing probes was measured. The response time and the reproducibility of the Fiber-optic temperature sensor were also obtained. Thermometry with the proposed sensor is immune to changes if parameters such as offset voltage, ambient temperature, and emissivity of any warm object. In particular, the temperature sensing probe with silver halide optical Fibers can withstand a high temperature/pressure and water-chemistry environment. It is expected that the proposed sensor can be further developed to accurately monitor temperature in harsh environments.

Bruno Bureau - One of the best experts on this subject based on the ideXlab platform.

  • Polymerisation of an industrial resin monitored by Infrared Fiber evanescent wave spectroscopy
    Sensors and Actuators B: Chemical, 2009
    Co-Authors: M.-l. Anne, E. Le Gal La Salle, Bruno Bureau, J. Tristant, F. Brochot, Catherine Boussard-plédel, Xianghua Zhang, Jean-luc Adam
    Abstract:

    In order to monitor the polymerisation process of an industrial resin, a study by Infrared Fiber evanescent wave spectroscopy has been carried out. To design the optical Fiber, a special glass composition has been optimized in the Se-Sb-Ge-Ga vitreous quaternary system. This glass exhibits a large transparency in the mid-Infrared range, and shows a temperature-viscosity behaviour that enables the preparation of optical Fibers. Most important is the glass transition temperature, which is high enough to allow Fiber measurement at about 200 °C. Infrared spectra have been recorded every 5 min during the curing process of the resin. A direct measurement of the integrated intensities of the relevant absorption band enabled to determine the times when the curing process started and when it finished. This direct analysis has been confirmed by principle component analysis, which is an unsupervised and very efficient method for applications at the industrial scale. Moreover, it has been shown that an autocatalytic kinetic model should be used to give a good account for the absorbency evolution versus time. From a practical point of view, the optical Fiber can be integrated directly into the mould and be considered as a consumable. The use of chalcogenide glass Fiber to record remotely Infrared signals, coupled with modern spectral analysis techniques constitute a very powerful route for monitoring the curing of thermo-hardening resins.

  • Optical analysis of Infrared spectra recorded with tapered chalcogenide glass Fibers
    Optical Materials, 2004
    Co-Authors: Steven Macdonald, Catherine Boussard-plédel, Karine Michel, David Le Coq, Bruno Bureau
    Abstract:

    Infrared Fiber evanescent wave spectroscopy (FEWS) spectra of water–ethanol mixtures are recorded and recon- structed thanks to a causal dispersion analysis technique. The complete expression of the complex reflection coefficients was used to determine the transmitted signal. The problems of shifting peaks or overlapping absorption bands from different chemical are well addressed. The effect of several parameters on the absorbance, such as the length of im- mersion and the diameter of the Fiber probe have been calculated and fit well with experimental data. More generally, the agreement between experimental and calculated spectra suggest the presented analysis technique is more accurate than other current analysis techniques.