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1.
Opt Express ; 25(1): 39-58, 2017 Jan 09.
Article in English | MEDLINE | ID: mdl-28085810

ABSTRACT

Here we present a new generic opto-bio-sensing platform combining immobilised aptamers on an infrared plasmonic sensing device generated by nano-structured thin film that demonstrates amongst the highest index spectral sensitivities of any optical fibre sensor yielding on average 3.4 × 104 nm/RIU in the aqueous index regime (with a figure of merit of 330) This offers a single stage, solution phase, atto-molar detection capability, whilst delivering real-time data for kinetic studies in water-based chemistry. The sensing platform is based upon optical fibre and has the potential to be multiplexed and used in remote sensing applications. As an example of the highly versatile capabilities of aptamer based detection using our platform, purified thrombin is detected down to 50 attomolar concentration using a volume of 1mm3 of solution without the use of any form of enhancement technique. Moreover, the device can detect nanomolar levels of thrombin in a flow cell, in the presence of 4.5% w/v albumin solution. These results are important, covering all concentrations in the human thrombin generation curve, including the problematic initial phase. Finally, selectivity is confirmed using complementary and non-complementary DNA sequences that yield performances similar to those obtained with thrombin.


Subject(s)
Biosensing Techniques/instrumentation , Optical Fibers , Thrombin/analysis , Humans , Kinetics
2.
Opt Express ; 19(1): 363-70, 2011 Jan 03.
Article in English | MEDLINE | ID: mdl-21263575

ABSTRACT

We present a novel device for the characterisation of static magnetic fields through monitoring wavelength shifts of femtosecond inscribed fibre Bragg grating and micromachined slot, coated with Terfenol-D. The device was sensitive to static magnetic fields and can be used as a vectoral sensor for the detection of magnetic fields as low as 0.046 mT with a resolution of ± 0.3mT in transmission and ± 0.7mT in reflection. The use of a femtosecond laser to both inscribe the FBGs and micromachine the slot in a single stage prior to coating the device significantly simplifies the fabrication.

3.
Appl Opt ; 48(2): 276-86, 2009 Jan 10.
Article in English | MEDLINE | ID: mdl-19137038

ABSTRACT

We demonstrate surface plasmon resonance (SPR) fiber devices based upon ultraviolet inscription of a grating-type structure into both single-layered and multilayered thin films deposited on the flat side of a lapped D-shaped fiber. The single-layered devices were fabricated from germanium, while the multilayered ones comprised layers of germanium, silica, and silver. Some of the devices operated in air with high coupling efficiency in excess of 40 dB and an estimated index sensitivity of Delta lambda/Delta n=90 nm from 1 to 1.15 index range, while others provided an index sensitivity of Delta lambda/Delta n=6790 nm for refractive indices from 1.33 to 1.37.


Subject(s)
Optical Fibers , Surface Plasmon Resonance/instrumentation , Equipment Design , Germanium/chemistry , Models, Statistical , Optics and Photonics , Refractometry , Reproducibility of Results , Silicon Dioxide/chemistry , Silver/chemistry , Surface Plasmon Resonance/methods , Ultraviolet Rays
4.
Opt Lett ; 32(7): 835-7, 2007 Apr 01.
Article in English | MEDLINE | ID: mdl-17339953

ABSTRACT

We present a high-capacity ultrafast all-optical time demultiplexer that can be employed to retrieve 40 gigabits/second (Gb/s) base-rate channels from a 640 Gb/s single-polarized signal. The demultiplexer utilizes ultrafast effects of filtered chirp of a semiconductor optical amplifier. Excellent demultiplexing performance is shown at very low switching powers: +8 dBm (640 Gb/s data) and -14 dBm (40 GHz clock). The demultiplexer has a simple structure and, in principle, allows monolithic integration.

5.
Opt Express ; 15(26): 18318-25, 2007 Dec 24.
Article in English | MEDLINE | ID: mdl-19551129

ABSTRACT

The influence of the fiber geometry on the point-by-point inscription of fiber Bragg gratings using a femtosecond laser is highlighted. Fiber Bragg gratings with high spectral quality and strong first-order Bragg resonances within the C-band are achieved by optimizing the inscription process. Large birefringence (1.2x10(-4)) and high degree of polarization-dependent index modulation are observed in these gratings. Potential applications of these gratings in resonators are further illustrated.


Subject(s)
Optical Fibers , Refractometry/instrumentation , Computer-Aided Design , Equipment Design , Equipment Failure Analysis , Reproducibility of Results , Sensitivity and Specificity
6.
Opt Lett ; 31(17): 2559-61, 2006 Sep 01.
Article in English | MEDLINE | ID: mdl-16902618

ABSTRACT

Microchannels are fabricated into conventional single-mode fibers by femtosecond laser processing and chemical etching. Fabrication limitations imposed by the fiber geometry are highlighted and resolved through a simple technique without compromising fabrication flexibility. A microfluidic fiber device consisting of a 4 microm wide microchannel that intersects the fiber core for refractive index sensing is further demonstrated.

7.
Opt Lett ; 31(11): 1672-4, 2006 Jun 01.
Article in English | MEDLINE | ID: mdl-16688257

ABSTRACT

A femtosecond laser inscription technique is proposed for the fabrication of a fiber grating laser directly into a nonphotosensitive gain fiber. A distributed Bragg reflector fiber grating laser is realized in a conventional, untreated Er:Yb-codoped fiber as an illustration. Robust, single-mode, single-polarization laser operation at temperatures in excess of 600 degrees C is further achieved without compromising performance. A nonlinear, thermally induced wavelength shift is also observed at elevated temperatures.

8.
Opt Lett ; 28(24): 2446-8, 2003 Dec 15.
Article in English | MEDLINE | ID: mdl-14690110

ABSTRACT

We propose and demonstrate single- and multiple-passband fiber grating transmission filters that are remotely tunable by exploitation of the optical pump-induced thermal effects in Er/Yb-codoped fiber sections. A repeatable, wavelength-independent induced phase shift of 0.1 pi/mW is obtained without hysteresis and anisotropic effects. A transmission extinction ratio of >23 dB with a 3-mW change in pump power is achieved.

9.
Opt Lett ; 28(6): 387-9, 2003 Mar 15.
Article in English | MEDLINE | ID: mdl-12659255

ABSTRACT

We describe what is to our knowledge the first use of fiber Bragg gratings written into three separate cores of a multicore fiber for two-axis curvature measurement. The gratings act as independent, but isothermal, fiber strain gauges for which local curvature determines the difference in strain between cores, permitting temperature-independent bend measurement.

10.
Opt Lett ; 27(8): 586-8, 2002 Apr 15.
Article in English | MEDLINE | ID: mdl-18007870

ABSTRACT

We report the observation of abnormal spectral evolution in regenerated fiber Bragg gratings in hydrogenated B-Ge-codoped and standard telecom fiber with UV overexposure. The behavior of this new type of regenerated grating, which we have designated type IA, contrasts with that of the previously reported type IIA grating in nonhydrogenated fiber by exhibiting a large redshift in Bragg wavelength with increasing exposure of as much as 18 nm from a strong (16-dB) regenerated grating in B-Ge fiber.

11.
Opt Lett ; 26(11): 774-6, 2001 Jun 01.
Article in English | MEDLINE | ID: mdl-18040446

ABSTRACT

We present a novel scheme for simultaneous measurement of temperature and refractive index by use of a single sampled fiber Bragg grating (SFBG). The intrinsic nature of a SFBG that possesses both fiber Bragg grating and long-period grating spectral responses permits the temperature effect to the measured solely from the former, whereas the refractive-index information is extracted from the latter. Using such a dual-parameter sensor, we successfully demonstrated measurement of the dependence on temperature of the refractive index of an aqueous solution of sucrose.

12.
Opt Lett ; 26(22): 1755-7, 2001 Nov 15.
Article in English | MEDLINE | ID: mdl-18059688

ABSTRACT

We report a theoretical and experimental investigation of the dispersion property of long-period fiber gratings in B/Ge codoped fiber. A novel concept of a mode ultrasensitive zone defined by a region in which the phase-matching conditions are close to the dispersion turning points is proposed. The transition from a dual-resonance state to a dispersion turning point is revealed for a set of ultrasensitive-zone gratings during the UV-writing process. We explore the sensitivity characteristics near the dispersion turning points, with the aim of implementing two types of temperature sensor with sensitivity 2 orders of magnitude higher than that of the conventional long-period gratings.

13.
J Biomed Opt ; 5(1): 45-50, 2000 Jan.
Article in English | MEDLINE | ID: mdl-10938765

ABSTRACT

We describe the results of in-vivo trials of a portable fiber Bragg grating based temperature profile monitoring system. The probe incorporates five Bragg gratings along a single fiber and prevents the gratings from being strained. Illumination is provided by a superluminescent diode, and a miniature CCD based spectrometer is used for demultiplexing. The CCD signal is read into a portable computer through a small A/D interface; the computer then calculates the positions of the center wavelengths of the Bragg gratings, providing a resolution of 0.2 degree C. Tests were carried out on rabbits undergoing hyperthermia treatment of the kidney and liver via inductive heating of metallic implants and comparison was made with a commercial Fluoroptic thermometry system.


Subject(s)
Body Temperature/physiology , Carcinoma/physiopathology , Kidney/physiology , Liver Neoplasms/physiopathology , Thermography/instrumentation , Animals , Biocompatible Materials , Carcinoma/therapy , Electrodes, Implanted , Equipment Design , Hyperthermia, Induced/instrumentation , Image Processing, Computer-Assisted , Liver Neoplasms/therapy , Metals , Prostheses and Implants , Rabbits
14.
Opt Lett ; 24(12): 802-4, 1999 Jun 15.
Article in English | MEDLINE | ID: mdl-18073859

ABSTRACT

We show experimentally and numerically that in high-speed strongly dispersion-managed standard fiber soliton systems nonlinear interactions limit the propagation distance. We present results that show that the effect of these interactions can be significantly reduced by appropriate location of the amplifier within the dispersion map. Using this technique, we have been able to extend the propagation distance of 10-Gbit/s 2(31)-1pseudorandom binary sequence soliton data to 16, 500 km over standard fiber by use of dispersion compensation. To our knowledge this distance is the farthest transmission over standard fiber without active control ever reported, and it was achieved with the amplifier placed after the dispersion-compensating fiber in a recirculating loop.

15.
Opt Lett ; 23(21): 1665-7, 1998 Nov 01.
Article in English | MEDLINE | ID: mdl-18091877

ABSTRACT

High-rejection-low-loss single-passband filters have been successfully fabricated by the chirped-grating concatenation method in a cladding depressed fiber. The enhanced photosensitivity, the enlarged bandgap between the Bragg resonance and the cladding modes, and the effective suppression of the cladding-mode outcoupling of the cladding depressed fiber permitted what is to our knowledge the first achievement of an ~1-dB loss in the passband and 50-dB rejection for a 50-nm-wide stop band covering the entire amplified spontaneous emission spectral range of an Er-doped fiber amplifier.

16.
Appl Opt ; 37(34): 8120-8, 1998 Dec 01.
Article in English | MEDLINE | ID: mdl-18301706

ABSTRACT

We investigate the feasibility of using in-fiber Bragg gratings for measuring acoustic fields in the megahertz range. We found that the acoustic coupling from the ultrasonic field to the grating leads to the formation of standing waves in the fiber. Because of these standing waves, the system response is complex and, as we show, the grating does not act as an effective probe. However, significant improvement in its performance can be gained by use of short gratings coupled with an appropriate desensitization of the fiber. A noise-limited pressure resolution of approximately 4.5 x 10(-3) atm/ radicalHz was found.

17.
J Biomed Opt ; 3(1): 38-44, 1998 Jan.
Article in English | MEDLINE | ID: mdl-23015004

ABSTRACT

Two in-fiber Bragg grating (FBG) temperature sensor systems for medical applications are demonstrated: (1) an FBG flow-directed thermodilution catheter based on interferometric detection of wavelength shift that is used for cardiac monitoring; and (2) an FBG sensor system with a tunable Fabry-Perot filter for in vivo temperature profiling in nuclear magnetic resonance (NMR) machines. Preliminary results show that the FBG sensor is in good agreement with electrical sensors that are widely used in practice. A field test shows that the FBG sensor system is suitable for in situ temperature profiling in NMR machines for medical applications. © 1998 Society of Photo-Optical Instrumentation Engineers.

18.
Opt Lett ; 22(17): 1326-8, 1997 Sep 01.
Article in English | MEDLINE | ID: mdl-18188228

ABSTRACT

We demonstrate simultaneous demultiplexing, data regeneration and clock recovery at 10Gbits/s, using a single semiconductor optical amplifier-based nonlinear-optical loop mirror in a phase-locked loop configuration.

19.
Opt Lett ; 22(19): 1473-5, 1997 Oct 01.
Article in English | MEDLINE | ID: mdl-18188272

ABSTRACT

We report on the fabrication of in-fiber moiré filters by dual exposure of a nondedicated chirped phase mask. This simple technique produces broadband filters whose structure depends only on an intermediate stretch between two identical UV exposures. We demonstrate moiré filters with as many as four narrow passbands within a 2-nm stopband.

20.
Opt Lett ; 21(9): 683-5, 1996 May 01.
Article in English | MEDLINE | ID: mdl-19876124

ABSTRACT

A spatial/wavelength-division multiplexing topology with combination of a tunable-wavelength filter and an interferometric wavelength scanner is used to interrogate a range of fiber Bragg grating (FBG) strain sensors embedded in modern composite materials. A nine-element FBG sensor system based on this topology is demonstrated for quasi-static strain sensing of a carbon fiber reinforced plastic plate for aerospace applications. Preliminary experimental results show that a strain resolution of ~1.8micro rms with an ~30-Hz bandwidth (~0.32micro/ radicalHz) for quasi-static strain measurement has been achieved.

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