The Experts below are selected from a list of 2919 Experts worldwide ranked by ideXlab platform

Linh Nguyen - One of the best experts on this subject based on the ideXlab platform.

  • simultaneous measurement of temperature and refractive index using an exposed core Microstructured Optical Fiber
    IEEE Journal of Selected Topics in Quantum Electronics, 2020
    Co-Authors: Linh Nguyen, Martin Becker, Heike Ebendorffheidepriem, Dinh Pham, Stephen C Warrensmith
    Abstract:

    We have demonstrated a novel scheme for simultaneous measurement of temperature and refractive index by using an exposed core Microstructured Optical Fiber (ECF). The ECF allows for high sensitivity to refractive index due to the small exposed-core, while being supported by a standard Fiber diameter cladding making it robust compared to Optical microFibers. The sensor combines a Fiber Bragg grating (FBG) inscribed into the core of the ECF and a multimode Mach–Zehnder interferometer (MZI). Both the FBG and MZI are sensitive to refractive index (RI) and temperature through a combination of direct access to the evanescent field via the exposed-core, the thermo-optic effect, and thermal expansion. The FBG and MZI respond differently to changes in temperature and RI, thus allowing for the simultaneous measurement of these parameters. In our experiment, RI sensitivities of 5.85 nm/RIU and 794 nm/RIU, and temperature sensitivities of 8.72 pm/°C and −57.9 pm/°C, were obtained for the FBG and MZI respectively. We demonstrate that a transfer matrix approach can be used to simultaneously measure both parameters, solving the problem of temperature sensitivity of RI sensors due to the high thermo-optic coefficient of aqueous samples.

  • high sensitivity sagnac interferometer biosensor based on exposed core Microstructured Optical Fiber
    Sensors and Actuators B-chemical, 2018
    Co-Authors: Yong Zhao, Heike Ebendorffheidepriem, Linh Nguyen, Stephen C Warrensmith
    Abstract:

    Abstract A novel, high sensitivity Sagnac-interferometer biosensor based on exposed core Microstructured Optical Fiber (ECF) has been designed and implemented in this paper. The exposed core Fiber has noncircular symmetry and thus exhibits birefringence and can form a sensing element within a Sagnac loop interferometer. The exposed-core Fiber design provides direct access to the evanescent field, allowing the measurement of bulk refractive index (RI) with a sensitivity of up to −3137 nm/RIU while maintaining the Fiber’s robustness. The sensor can also detect the localized refractive index changes at the Fiber core’s surface as the result of a biological binding event. We demonstrate the use of this sensor for label-free sensing of biological molecules by immobilizing biotin onto the Fiber core as the probe to capture the target molecule streptavidin.

  • Interferometric-type Optical biosensor based on exposed core Microstructured Optical Fiber
    Sensors and Actuators B-chemical, 2015
    Co-Authors: Linh Nguyen, Stephen C. Warren-smith, Kelly Hill, Tanya M Monro
    Abstract:

    Abstract This work presents a novel biosensor using the multimode interference effect in an exposed core Microstructured Optical Fiber (ECF). In this work biotin molecules are immobilized onto the ECF core surface to serve as the capturing probe for streptavidin, the target molecules. Since each distinct guided mode in the ECF interacts with the surrounding medium differently, the interference between any two specific modes will experience a fringe shift (or phase change) upon a change in the refractive index (RI) of the surrounding medium, or a localized RI change on the surface of the ECF core as a result of a biological binding event. In our experiment, the interferometric sensing platform was realized by splicing a section of ECF with lead-in and lead-out single mode Fibers (SMFs). An interference pattern is obtained in the transmission spectrum as the result of multiple excited modes (excited and re-collected at the lead-in and lead-out splicing points) propagating in the ECF with different propagation constants. The interference pattern is non-uniform, indicating that there are more than two modes involved. Fast Fourier transform (FFT) is used to separate individual interference patterns that contribute to this complex spectrum and monitor their phase changes upon RI variation of the surrounding medium. In this way multiple RI sensitivities can be realized because each spatial frequency possesses a distinct sensitivity with respect to the surrounding RI. The operation of this device was validated by measuring the phase changes that occur when the sensing platform was subjected to solutions of different RIs or functionalized with different molecules. A biosensor was demonstrated based on this novel platform using biotin as the capturing probe to specifically detect streptavidin with low non-specific adsorption. The proposed platform is reliable, cost-effective, and offers a potential label-free biosensing alternative to the widely used surface plasmon resonance (SPR) technique.

Benjamin John Eggleton - One of the best experts on this subject based on the ideXlab platform.

  • Ultrasensitive photonic crystal Fiber refractive index sensor
    Optics Letters, 2009
    Co-Authors: Darran K C Wu, Boris T Kuhlmey, Benjamin John Eggleton
    Abstract:

    We introduce a microfluidic refractive index sensor based on a directional coupler architecture using solid-core photonic crystal Fibers. The sensor achieves very high sensitivity by coupling the core mode to a mode in the adjacent fluid-filled waveguide that is beyond modal cutoff, and with strong field overlap. We demonstrate the device through the selective infiltration of a single hole with fluid along a Microstructured Optical Fiber. A detection limit of 4.6×10−7 refractive index units has been derived from measurements with a sensitivity of 30,100 nm per refractive index unit, which is the highest for a Fiber device to date.

  • Microfluidic tunable photonic band-gap device
    Applied Physics Letters, 2004
    Co-Authors: Peter Domachuk, Markus Straub, H. C. Nguyen, Benjamin John Eggleton, M Gu
    Abstract:

    We introduce a method for tuning a photonic band-gapmaterial by means of displacing microfluidic plugs. The fluid is introduced into air voids that constitute the structure of the photonic crystal and is displaced using a capillary heater. The photonic crystal geometry is obtained using a Microstructured Optical Fiber, comprising a periodically spaced array of air holes that is interrogated in the transverse direction, creating a “tall microchip.” Optical spectra are compared to band structure calculations of an idealized band-gapmaterial.

  • numerical analysis and experimental design of tunable birefringence in Microstructured Optical Fiber
    Optics Express, 2002
    Co-Authors: Charles Kerbage, Benjamin John Eggleton
    Abstract:

    We present detailed experimental and numerical results for birefringence tuning in Microstructured Optical Fibers. Index tunable polymer is infused into specific air-holes to obtain birefringence whose tunability is achieved by temperature tuning the polymer index. We also study the symmetry properties of the modes for different waveguide structures.

  • Highly tunable birefringent Microstructured Optical Fiber.
    Optics letters, 2002
    Co-Authors: Charles Kerbage, Paul Steinvurzel, A. Hale, Robert S. Windeler, P Reyes, Paul S Westbrook, Benjamin John Eggleton
    Abstract:

    We demonstrate a method for introducing and dynamically tuning birefringence in a Microstructured Optical Fiber. Waveguide asymmetry in the Fiber is obtained by selective filling of air holes with polymer, and tunability is achieved by temperature tuning of the polymer's index. The Fiber is tapered such that the mode field expands into the cladding and efficiently overlaps the polymer that has been infused into the air holes, ensuring enhanced tunability and low splice loss. Experimental results are compared with numerical simulations made with the beam propagation method and confirm birefringence tuning that corresponds to a phase change of 6pi for a 1-cm length of Fiber.

  • Microstructured Optical Fiber devices.
    Optics express, 2001
    Co-Authors: Benjamin John Eggleton, P Westbrook, Robert S. Windeler, Charles Kerbage, A. Hale
    Abstract:

    We present several applications of Microstructured Optical Fibers and study their modal characteristics by using Bragg gratings inscribed into photosensitive core regions designed into the air-silica microstructure. The unique characteristics revealed in these studies enable a number of functionalities including tunability and enhanced nonlinearity that provide a platform for Fiber device applications. We discuss experimental and numerical tools that allow characterization of the modes of the Fibers.

Stephen C Warrensmith - One of the best experts on this subject based on the ideXlab platform.

  • simultaneous measurement of temperature and refractive index using an exposed core Microstructured Optical Fiber
    IEEE Journal of Selected Topics in Quantum Electronics, 2020
    Co-Authors: Linh Nguyen, Martin Becker, Heike Ebendorffheidepriem, Dinh Pham, Stephen C Warrensmith
    Abstract:

    We have demonstrated a novel scheme for simultaneous measurement of temperature and refractive index by using an exposed core Microstructured Optical Fiber (ECF). The ECF allows for high sensitivity to refractive index due to the small exposed-core, while being supported by a standard Fiber diameter cladding making it robust compared to Optical microFibers. The sensor combines a Fiber Bragg grating (FBG) inscribed into the core of the ECF and a multimode Mach–Zehnder interferometer (MZI). Both the FBG and MZI are sensitive to refractive index (RI) and temperature through a combination of direct access to the evanescent field via the exposed-core, the thermo-optic effect, and thermal expansion. The FBG and MZI respond differently to changes in temperature and RI, thus allowing for the simultaneous measurement of these parameters. In our experiment, RI sensitivities of 5.85 nm/RIU and 794 nm/RIU, and temperature sensitivities of 8.72 pm/°C and −57.9 pm/°C, were obtained for the FBG and MZI respectively. We demonstrate that a transfer matrix approach can be used to simultaneously measure both parameters, solving the problem of temperature sensitivity of RI sensors due to the high thermo-optic coefficient of aqueous samples.

  • high sensitivity sagnac interferometer biosensor based on exposed core Microstructured Optical Fiber
    Sensors and Actuators B-chemical, 2018
    Co-Authors: Yong Zhao, Heike Ebendorffheidepriem, Linh Nguyen, Stephen C Warrensmith
    Abstract:

    Abstract A novel, high sensitivity Sagnac-interferometer biosensor based on exposed core Microstructured Optical Fiber (ECF) has been designed and implemented in this paper. The exposed core Fiber has noncircular symmetry and thus exhibits birefringence and can form a sensing element within a Sagnac loop interferometer. The exposed-core Fiber design provides direct access to the evanescent field, allowing the measurement of bulk refractive index (RI) with a sensitivity of up to −3137 nm/RIU while maintaining the Fiber’s robustness. The sensor can also detect the localized refractive index changes at the Fiber core’s surface as the result of a biological binding event. We demonstrate the use of this sensor for label-free sensing of biological molecules by immobilizing biotin onto the Fiber core as the probe to capture the target molecule streptavidin.

Yasutake Ohishi - One of the best experts on this subject based on the ideXlab platform.

Tanya M Monro - One of the best experts on this subject based on the ideXlab platform.

  • Interferometric-type Optical biosensor based on exposed core Microstructured Optical Fiber
    Sensors and Actuators B-chemical, 2015
    Co-Authors: Linh Nguyen, Stephen C. Warren-smith, Kelly Hill, Tanya M Monro
    Abstract:

    Abstract This work presents a novel biosensor using the multimode interference effect in an exposed core Microstructured Optical Fiber (ECF). In this work biotin molecules are immobilized onto the ECF core surface to serve as the capturing probe for streptavidin, the target molecules. Since each distinct guided mode in the ECF interacts with the surrounding medium differently, the interference between any two specific modes will experience a fringe shift (or phase change) upon a change in the refractive index (RI) of the surrounding medium, or a localized RI change on the surface of the ECF core as a result of a biological binding event. In our experiment, the interferometric sensing platform was realized by splicing a section of ECF with lead-in and lead-out single mode Fibers (SMFs). An interference pattern is obtained in the transmission spectrum as the result of multiple excited modes (excited and re-collected at the lead-in and lead-out splicing points) propagating in the ECF with different propagation constants. The interference pattern is non-uniform, indicating that there are more than two modes involved. Fast Fourier transform (FFT) is used to separate individual interference patterns that contribute to this complex spectrum and monitor their phase changes upon RI variation of the surrounding medium. In this way multiple RI sensitivities can be realized because each spatial frequency possesses a distinct sensitivity with respect to the surrounding RI. The operation of this device was validated by measuring the phase changes that occur when the sensing platform was subjected to solutions of different RIs or functionalized with different molecules. A biosensor was demonstrated based on this novel platform using biotin as the capturing probe to specifically detect streptavidin with low non-specific adsorption. The proposed platform is reliable, cost-effective, and offers a potential label-free biosensing alternative to the widely used surface plasmon resonance (SPR) technique.

  • Exposed core Microstructured Optical Fiber Bragg gratings: refractive index sensing.
    Optics Express, 2014
    Co-Authors: Stephen C. Warren-smith, Tanya M Monro
    Abstract:

    Bragg gratings have been written in exposed-core Microstructured Optical Fibers for the first time using a femtosecond laser. Second and third order gratings have been written and both show strong reflectivity at 1550 nm, with bandwidths as narrow as 60 pm. Due to the penetration of the guided field outside the Fiber the Bragg reflections are sensitive to the external refractive index. As different modes have different sensitivities to refractive index but the same temperature sensitivity the sensor can provide temperature-compensated refractive index measurements. Since these Bragg gratings have been formed by physical ablation, these devices can also be used for high temperature sensing, demonstrated here up to 800°C. The Fibers have been spliced to single mode Fiber for improved handling and integration with commercial interrogation units.

  • fabrication and supercontinuum generation in dispersion flattened bismuth Microstructured Optical Fiber
    Optics Express, 2011
    Co-Authors: Wen Qi Zhang, Tanya M Monro, Heike Ebendorffheidepriem, Shahraam V Afshar
    Abstract:

    We fabricated a Microstructured Optical Fiber with a dispersion profile that, according to calculations, is near-zero and flat, with 3 zero dispersion wavelengths in the mid-IR. To the best of our knowledge this is the first report of the fabrication of such a Fiber. Simulations of multimode supercontinuum generation were performed using a simplified approach. Strong agreement between experiments and simulations were observed using this approach.

  • highly efficient excitation and detection of whispering gallery modes in a dye doped microsphere using a Microstructured Optical Fiber
    Applied Physics Letters, 2011
    Co-Authors: Alexandre Francois, Kristopher J Rowland, Tanya M Monro
    Abstract:

    A technique for the excitation of whispering gallery modes (WGMs) has been demonstrated using a dye-doped microsphere positioned onto the tip of a suspended core Microstructured Optical Fiber. With this configuration, we have shown that both the excitation and collection efficiency of the WGMs modulated fluorescence spectra of the dye are greatly improved compared to a more conventional excitation scheme; an overall efficiency increase by a factor of 200 is demonstrated. It is also shown that positioning the resonator onto the Fiber tip does not impact its sensitivity, providing a compact and robust architecture for applications such as localized in-vivo/vitro biosensing.

  • extruded single mode high index core one dimensional Microstructured Optical Fiber with high index contrast for highly nonlinear Optical devices
    Applied Physics Letters, 2005
    Co-Authors: Xian Feng, Tanya M Monro, P Petropoulos, V Finazzi, D J Richardson
    Abstract:

    We report the fabrication of a high-index-core one-dimensional Microstructured Optical Fiber incorporating with high index-contrast layers, using extrusion technique for preform fabrication. Single mode guidance and a high effective nonlinearity of 260±30W−1km−1 were observed in the Fiber at 1.55μm, highlighting the potential of such Fibers for use in nonlinear Optical devices.