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Early Access Articles

Early Access articles are new content made available in advance of the final electronic or print versions and result from IEEE's Preprint or Rapid Post processes. Preprint articles are peer-reviewed but not fully edited. Rapid Post articles are peer-reviewed and edited but not paginated. Both these types of Early Access articles are fully citable from the moment they appear in IEEE Xplore.

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Displaying Results 26 - 50 of 133
  • Fiber Specklegram Multiplexed Sensor

    Publication Year: 2014 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (857 KB)  

    In this work, several multiplexing techniques have been combined to achieve a Fiber Specklegram Multiplexed Sensor (FSMS). Using a single CCD camera as detector, two lasers of different wavelengths have been launched into two multimode Polymer Optical Fibers (POFs) and then combined through a 2x2 coupler before their interrogation. Both coupler exit fibers have been projected to different CCD positions and by analyzing each color of the video sequence, the four fiber channels can be independently obtained. In addition, the speckle sensitivity has been also studied analyzing different properties of speckle patterns such as their contrast or the speckle size. The achieved results will be very useful to the development of new fiber specklegram sensors with several sensing areas using only a CCD camera as detector, making possible low cost sensing devices. View full abstract»

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  • Spectral Efficiency Optimization in Flexi-Grid Long-Haul Optical Systems

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (751 KB)  

    Flexible grid optical networks allow a better exploitation of fiber capacity, by enabling a denser frequency allocation. A tighter channel spacing, however, requires narrower filters, which increase linear intersymbol interference (ISI), and may dramatically reduce system reach. Commercial coherent receivers are based on symbol by symbol detectors, which are quite sensitive to ISI. In this context, Nyquist spacing is considered as the ultimate limit to wavelength-division multiplexing (WDM) packing. In this paper, we show that by employing a limited-complexity trellis processing at the receiver, either the reach of Nyquist WDM flexi-grid networks can be significantly extended, or a denser-than-Nyquist channel packing (i.e., a higher spectral efficiency (SE)) is possible at equal reach. By adopting wellknown information-theoretic techniques, we design a limitedcomplexity trellis processing and quantify its SE gain in flexigrid architectures where wavelength selective switches over a frequency grid of 12.5GHz are employed. View full abstract»

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  • Surface plasmon resonance based fiber optic chlorine gas sensor utilizing indium oxide doped tin oxide film

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (437 KB)  

    Fabrication and characterization of a surface plasmon resonance (SPR) based fiber optic chlorine gas sensor are carried out. The fiber optic probe is fabricated by depositing a thin layer of indium oxide doped tin oxide over a silver coated unclad core of the fiber. The SPR spectra of the chlorine gas for its different concentrations are obtained. It is observed that the resonance wavelength increases as the concentration of the chlorine gas increases and appears to saturate for higher concentrations of the gas. The sensitivity of the sensor depends on the thickness and the doping concentration of the indium oxide doped tin oxide film. The optimum thickness and the atomic weight percent doping concentration of the film are found to be 12 nm and 6 at. wt.% respectively. To compare the performance, experiments are also carried out on probes coated with indium oxide and tin oxide layers over silver coated unclad core of the fiber. The performance of both the probes is found to be inferior to the one coated with indium oxide doped tin oxide layer. Further, the indium oxide doped tin oxide layer based probe is highly sensitive to chlorine gas for low concentrations. The sensor has low response time and is reversible. The proposed probe has advantages of online monitoring and remote sensing. View full abstract»

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  • A High Spectral Efficiency Coherent Microwave Photonic Link Employing Both Amplitude and Phase Modulation With Digital Phase Noise Cancellation

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (743 KB)  

    A high spectral efficiency coherent microwave photonic link (MPL) supporting amplitude and phase modulation incorporating digital phase noise cancellation is proposed and experimentally demonstrated. At the transmitter, a continu-ous-wave (CW) light wave is amplitude- and phase-modulated by two microwave vector signals carried by a microwave carrier at an identical frequency. The modulated optical signal is polariza-tion multiplexed with an unmodulated optical carrier and trans-mitted over a length of single-mode fiber (SMF). At the receiver, the optical signal is detected coherently by a coherent receiver to which a local oscillator (LO) laser source is also applied. Through advanced digital signal processing (DSP), the microwave vector signals are recovered and the phase noise introduced by both the transmitter laser source and LO laser source is cancelled. An experiment is performed. The transmission of a 2.5-Gbps 16-QAM and a 1.25-Gbps QPSK microwave vector signals both at 2.5 GHz over a 25-km SMF is implemented. The total bit rate of the MPL is 3.75 Gbps. The transmission performance of the MPL in terms of error vector magnitudes (EVMs) and bit error rates (BERs) is evaluated. View full abstract»

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  • Gaseous oxygen detection using hollow-core fiber-based linear cavity ring-down spectroscopy

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (828 KB)  

    We demonstrate a method for the calibration-free and quantitative analysis of small volumes of gaseous samples. A 10m hollow-core photonic bandgap fiber is used as the sample cell (volume = 0.44 μL) and is placed inside a linear resonator setup. The application of cavity ring-down spectroscopy and in consideration of rather small coupling losses, this leads to an increased effective optical path length of up to 70m. This implies a volume per optical interaction path length of 6.3 nL m−1. We used tunable diode laser spectroscopy at 760 nm and scanned the absorption for oxygen sensing. The optical loss due to sample absorption is obtained by measuring the ring-down time of light propagating inside the cavity. The resultant absorption coefficient shows a discrepancy of only 5.1% comparing to the HITRAN database. This approach is applicable for sensitive measurements if only sub-microliter sample volumes are available. View full abstract»

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  • Fully-Switchable Multi-Wavelength Fiber Lasers Based on Random Distributed Feed-Back for Sensors Interrogation

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1698 KB)  

    In this paper, the experimental study and characterization of a novel real-time switchable multi-wavelength fiber laser has been carried out. Two different gain materials, such as a 50 km SMF and a 2.5 km DCF fibers were characterized and compared, respectively. The MWFL can generate any wavelength combination with an emission lines distance of 50, 100 and 200 GHz fitting the ITU grid specifications. By using both Er-doped fiber and Raman amplification, a ~30 nm wide lasing window at the C band can be utilized to create up to 30 different lasing wavelengths into the ITU Grid, that can be switched automatically and in real-time when desired. Utilization of such a laser for versatile interrogation of different sensing networks is also shown. View full abstract»

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  • An Electrically-Controlled Nematic Liquid Crystal Core Waveguide With a Low Switching Threshold

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (561 KB)  

    We demonstrate an electrically-controlled liquid crystal (LC) core waveguide, using 5CB (4-Cyano-4'-pentylbiphenyl) nematic liquid crystal, fabricated on a glass substrate. A negative photoresist, AZ15nXT layer was coated on the glass substrate to realize a channel waveguide of core thickness 4.8 μm. The LC core waveguide exhibits strong differential attenuation for propagation of the TE- (horizontal) and TM- like (vertical) polarizations of light. The experimental results show that the output power suddenly drops down by several dB at an applied voltage of 1 V, for a waveguide of length 10 mm, due to the re-orientation of the LC molecules. The waveguide can be used as an optical switch, as well as an optical attenuator. View full abstract»

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  • A Simultaneous Variable Optical Weight and Delay in a Semiconductor Optical Amplifier for Microwave Photonics

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2069 KB)  

    In this paper, we demonstrate how a single semiconductor optical amplifier can serve as a simultaneous variable optical weight and tunable optical delay for microwave photonics. The device weight, or power transmission, and delay can be controlled simultaneously and independently from each other by varying the input optical power and the semiconductor bias current. The dual functionality is achieved by combining the effects of slow and fast light with cross-gain modulation in the semiconductor. We experimentally demonstrate a tunable delay range of 100 ps and RF gain range of -6 dB to +3 dB for a 600 MHz microwave signal and show how the weight and delay of the device can be separately tuned. The delay range and bandwidth of the device are limited by the semiconductor carrier lifetime, characteristic of slow and fast light. As a simultaneous optical weight and delay, as well as a wavelength converter, a semiconductor optical amplifier operating in this manner can be a compact and versatile element in microwave photonics, radioover- fiber, and general analog optical signal processing. View full abstract»

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  • Noise and bias error due to polarization coupling in a fiber optic gyroscope

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (784 KB)  

    This paper reports a comprehensive model of the noise and drift induced by polarization coupling in a fiber optic gyroscope (FOG) interrogated with a laser of arbitrary linewidth. It includes the effects of dynamic phase biasing, a realistic description of laser phase noise, and polarization-dependent loss. This model yields concise analytical expressions for the noise and drift dependencies on the laser linewidth, the fiber length and holding parameter h, and the fractional power launched into the unwanted polarization at the input to the sensing coil. For all realistic FOG parameter sets the polarization-coupling noise is found to be insignificant. For a 1-km coil, a typical holding parameter (h = 10-5), and push-pull modulation, the drift is only ~1 μrad up to a linewidth of ~100 MHz, which is far lower than previously believed. The drift decreases to even lower values for larger linewidths. Experimental measurements of the noise and drift in a 150-m FOG and their dependence on laser linewidth support these predictions. Birefringence modulation can be brought to bear to reduce this residual drift enough to meet the requirement for aircraft inertial navigation. Ultimately, this analysis shows that low polarization coupling error can be obtained without the use of a broadband source. View full abstract»

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  • Optical Metasurfaces and Prospect of Their Applications including Fiber Optics

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1705 KB)  

    Metasurfaces have emerged in the recent years as a platform to design subwavelength-thick optical components (“flat optics”), which can be used to implement any optical function (beam deflection, focusing, waveplates, etc). These flat optical components can be fabricated using a single lithographic step. The approach is particularly suited for patterning nonconventional substrates, such as semiconductor laser facets and optical fiber facets. In this paper, we review recent applications of metasurfaces to flat optical devices, including their use in semiconductor lasers and fiber optics. Metasurfaces make it possible to design all properties of light (amplitude, phase, and polarization), which enable us to build a large variety of flat optical components, including planar lenses, quarter-wave plates, optical vortex plates, holograms for vector beam generation, and ultrathin perfect absorbers and color coatings. We also review flat collimating lenses integrated on the facets of mid-infrared and far-infrared (terahertz) quantum cascade lasers, and novel techniques to create large arrays of nanostructures on fiber facets. View full abstract»

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  • An optical fibre hydrogen sensor using a palladium coated ball lens

    Publication Year: 2014 , Page(s): 1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (632 KB)  

    A self-referenced optical fibre refractometer using a ball lens as a sensor head has been developed and characterised. A 350μm ball lens created at the tip of a single mode fibre has been coated with a 40nm optically thin layer of palladium that reacts with hydrogen to form a hydride, which has a lower reflectivity than pure palladium. Optical reflectance measurements from the tip of the ball lens were performed to determine the hydrogen response. The change in reflectivity is proportional to the hydrogen concentration in the range 0 to 1% hydrogen in air with a detection limit down to 10ppm (1σ) in air. This technique offers a simple sensor head arrangement, with a large sampling area (~40 times) than a typical single-mode fibre core. A statistical image analysis of a palladium film, with cracks created by accelerated failure, confirms that the anticipated sensor area for a ball lens sensor head has a more predictable reflectivity than that of a bare fibre core. View full abstract»

    Open Access
  • Stable multi-wavelength erbium fiber ring laser with optical feedback for remote sensing

    Publication Year: 2014 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (595 KB)  

    In this work, we demonstrate a stable fiber sensing system for remote temperature measurements, where the sensing element is an array of four fiber Bragg gratings (FBGs) and sensor interrogation is achieved with a multi-wavelength erbium fiber ring laser. By introducing a feedback fiber loop in a fiber ring cavity, four laser emission lines were obtained simultaneously in single-longitudinal mode operation (SLM). The power instability obtained was lower than 0.5 dB with an optical signal-to-noise ratio (OSNR) higher than 50 dB for all the emitted wavelengths. The application of this system for remote temperature measurements has been demonstrated even though the SLM regime cannot be preserved. View full abstract»

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  • Compound lasing fiber optic ring resonators for sensor sensitivity enhancement

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (969 KB)  

    In this work, a new method for increasing simultaneously the sensitivity and interrogation stability of fiberoptic intensity sensors is presented. The configuration is based on a double-coupler ring resonator. On one side, the attenuation sensitivity of the sensor is enhanced by placing it inside a ring resonator. On the other side, the stability of the interrogation method is widely improved by creating an external lasing ring resonator with matched spectral response. The combination of the wavelength selective response of the ring resonator and optical amplification from Er-doped fiber amplifier is used to create different fiber lasers. The resulting lasers present an impressive sensitivity enhancement and a dynamic range increment up to 15 dB. Simultaneously, the instability of the system is reduced to ±0.05 dB. In comparison with systems based on tunable laser interrogation, our method is >100 times more stable and also simpler, as no wavelength tunable elements are required. View full abstract»

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  • Integrated Silicon Photovoltaics on CMOS with MEMS Module for Catheter Tracking

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3738 KB)  

    This work presents an electromagnetic actuation based, optoelectronic active catheter tracking system for magnetic resonance imaging (MRI). The system incorporates a radio frequency (RF) micro electro mechanical system (MEMS) resonator array actuated by the Lorentz force induced due to the strong dc magnetic field available in MRI environment. Power transfer to the system and the actuation detection are done optically via fiber optic cables that replace conventional conductive transmission lines; thereby enabling the tracking system to function safely under MRI. The complementary metaloxide- semiconductor (CMOS) receiver, optically powered by a supply unit housing an on-chip silicon photovoltaic cell, detects the location of the catheter tip. The RF MEMS resonator array transmits the position data by transducing the electrical signal into a resonant mechanical vibration linearly. The optical reading of this actuation can be done by diffraction grating interferometry or laser Doppler vibrometry. The fabricated resonator array is tested with the optically powered CMOS chip (0.18 m UMC technology) in laboratory conditions. The driving electrical current supplied by the chip for resonator actuation is 25 A rms, where the magnetic field provided by the experimental setup is 0.62 T. The resonator array is observed to be functional with real world application by showing a frequency response of 10 dB, which will be enhanced further under the stronger magnetic field available in 3 T MRI. View full abstract»

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  • Frequency-Domain Channel Estimation for Polarization-Division-MultiplexedCO-OFDM/OQAM Systems

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (547 KB)  

    Intrinsic imaginary interference (IMI) induced by multiple-path fading channel is an important impairment for orthogonal frequency division multiplexing offset-quadrature amplitude modulation (OFDM/OQAM) systems. Therefore the accurate channel estimation is highly desired for such system. Recently both the simulation studies and the experimental demonstrations for coherent optical OFDM/OQAM (CO-OFDM/OQAM) have been reported. However, there are no theoretical discussions on the IMI effect and the channel estimation method for polarization-division-multiplexed (PDM) CO-OFDM/OQAM systems so far. In this paper, we systematically analyze the frequency-domain optical fiber channel transmission model for PDM CO-OFDM/OQAM systems with the IMI effect induced by chromatic dispersion (CD) and polarization mode dispersion (PMD). The full loaded (FL) and the half loaded (HL) frequency-domain channel estimation methods are discussed to mitigate the IMI effect. The computational complexities and robustness against CD and PMD are also compared for both of the FL and the HL methods. The theoretical analysis is validated by numerical Monte Carlo simulations of PDM CO-OFDM/OQAM systems. View full abstract»

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  • Compensation of the Dispersion-Induced Power Fading in an Analog Photonic Link based on PM-IM Conversion in a Sagnac Loop

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (253 KB)  

    An analog photonic link (APL) with the compensation of the dispersion-induced power fading is proposed and demonstrated based on phase modulation to intensity modulation (PM-IM) conversion in a Sagnac loop. Due to the velocity mismatch of the modulator, only the incident light wave along the clockwise direction is effectively modulated by the radio frequency (RF) signals, while the counter-clockwise light wave is not modulated. After combining the two light waves in a polarizer, an intensity modulated optical signal is generated, which can be directly detected. In addition, the phase difference between the two light waves can be adjusted through the polarization controller before the polarizer. This feature is used to shift the frequency response of a dispersive link to compensate the dispersion-induced power fading at any working frequency. Experimental results show that the power fading after transmission over both 25 and 50 km lengths of fiber in a conventional intensity modulated link can be successfully compensated in the proposed link, and thus a high and constant link gain over a large frequency range is achieved. The spur free dynamic ranges (SFDRs) of the link before and after fiber transmission are also measured. View full abstract»

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  • Experimental investigation of supercontinuum generation in photonic crystal fibers pumped with sub-ns pulses

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (842 KB)  

    We experimentally investigate a supercontinuum generation in a series of photonic crystal fibers pumped with sub-ns pulses. The fibers are designed to have zero dispersion wavelengths close to 1064 nm, but they differ with respect to the lattice constant and air hole size. We focus on the supercontinuum generation mechanism and on the shape of spectra generated with the use of these photonic crystal fibers. A comprehensive study on the influence of the fiber structural parameters on the supercontinuum outcome indicates how to tailor these parameters for specific application where particular spectral characteristics are desired. View full abstract»

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  • Designing a Plasmonic Optophoresis System for Trapping and Simultaneous Sorting/Counting of Micro- and Nano-particles

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1276 KB)  

    We are proposing a plasmonic-based optophoresis system that can trap and simultaneously sort and count metallic and dielectric micro- and nano-particles, in a simple microfluidic system. The operating principles of the proposed system are based on the particles intrinsic properties that modulate the in-duced optical force and the transmitted power. Particle manipu-lations, in this system, are based on the near-field optical forces excreted by leaky surface plasmons modes, excited on a gold stripe. Simulations show that the maximum potential depth sensi-tivity to the trapped PS/Au particles’ radius is ~ 0.09/0.03 (kBT / nm). The maximum transmission sensitivity in response to a change in radii of trapped Au and PS spheres are both ~0.01% per nm. Moreover, it is also shown that a minute change of ±1% in a refractive index of a 250-nm trapped dielectric particle re-sults in ±0.26 kBT and ∓0.13% variations in the potential depth and transmission, respectively. Furthermore, the proposed sys-tem that can be implemented simply and inexpensively, benefits from its small footprint for integration into lab-on-a-chip devices and low power consumption, with promising potentials for bio-logical applications. View full abstract»

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  • Ultrafast and Low-power Dynamically Tunable Plasmon Induced Transparencies in Compact Aperture-Coupled Rectangular Resonators

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3853 KB)  

    In this paper, ultrafast and low-power dynamically tunable single and multiple plasmon induced transparencies (PITs) in ultracompact rectangular resonators aperture-coupled metal-dielectric-metal (MDM) waveguide system with nonlinear optical Kerr medium is investigated both analytically and numerically. Multiple PITs are realized in this plasmonic waveguide structure based on bright-dark mode coupling mechanism. High tunability in transparency window magnitude, phase shift and group index is obtained when nonlinear optical Kerr material is embedded in the MDM waveguide. In order to reduce the pump intensity, traditional nonlinear optical Kerr material is replaced by graphene. A shift of 45 nm in the central wavelength of the single transparency window is achieved when the rectangular resonators are covered by monolayer graphene with pump intensity increasing from 6.7 to 7.5 MW/cm2. Calculated results show that whole structure is ultracompact with the footprint of < 0.5 μm2 and an ultrafast response time of the order of 1ps can be reached. View full abstract»

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  • Polarization diversity scheme for BOTDA sensors based on a double orthogonal pump interaction

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (415 KB)  

    We introduce a Brillouin optical time domain analysis (BOTDA) sensor deploying a novel polarization diversity technique based on the use of two orthogonal pump pulses which simultaneously interact with a phase-modulated probe wave. The orthogonallity of the two pump pulses guarantees that two complementary Brillouin interactions take place at each position of the fiber, so that polarization independent measurements are performed throughout the fiber even if no averaging is applied. This feature can be exploited in dynamic distributed BOTDA sensors to reduce the measurement time, as no extra averaging is required to compensate the polarization dependence of Brillouin interaction. Proof-of-concept experiments demonstrate the feasibility of the technique by employing a completely passive scheme to generate the orthogonal pump pulses. Furthermore, the technique is stable and easy to implement, making it a perfect candidate for practical sensor implementations. View full abstract»

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  • Collapsed-hole Ge-doped Photonic Crystal Fiber as a Diagnostic Radiation Dosimeter

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (721 KB)  

    A new type of microstructured optical fiber, fabricated by collapsing down the entire array of holes formed by a Photonic Crystal Fibre (referred to herein as PCF-collapsed), is used in this study as an ionizing radiation dosimeter. The performance of the optical fiber is evaluated for diagnostic applications, covering doses from a fraction of 1 mGy up to 10 Gy. The effect of different x-ray beam accelerating potentials from 40 kVp up to 125 kVp photon beam, 6 MeV electrons, and 6 MV photons are demonstrated. The performance of the PCF-collapsed is compared with the uncollapsed PCF (PCF-structured) and a conventional 20-μm-core-diameter Optical Fiber, all three types of fiber being fabricated from the same Ge-doped-preforms. It is shown that while a PCF-structured has relatively low sensitivity, by collapsing all of the holes in the PCF, the TL response of the fiber is increased by more than 16 times, being also more than 4 times greater than that of the conventional form Optical Fiber. The PCF-collapsed can detect a minimum dose as low as 0.6 mGy measured and 5.75 ±0.11 mGy calculated. The TL analysis suggests that a collapsed-hole-PCF enhances structural defects in an uncollapsed-hole-PCF, highly desirable for dosimeter applications. View full abstract»

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  • Distance Adaptive Dynamic Routing and Spectrum Allocation in Elastic Optical Networks with Shared Backup Path Protection

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (479 KB)  

    This paper considers distance adaptive dynamic routing and spectrum assignment (RSA) for elastic optical networks with shared backup path protection (SBPP). Efficient heuristic algorithms based on spectrum window planes (SWPs) are proposed for implementing distance and modulation format adaptive RSA so as to maximize spare capacity sharing among multiple protection lightpaths. A differentiated sharable frequency slot (FS) cost was also defined for the first time to more efficiently share protection resource. Network performance is evaluated in terms of bandwidth blocking probability (BBP) through simulations. The proposed SBPP technique is effective in reducing bandwidth blocking probability and improving spectral efficiency compared to conventional SBPP schemes and 1+1 path protection. The impact of transponder tunability on bandwidth blocking performance is also evaluated to show that a limited tuning range is sufficient to achieve a BBP performance close to that with full tunability. View full abstract»

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  • Quantum optical technologies for metrology, sensing and imaging

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6875 KB)  

    Over the past 20 years, bright sources of entangled photons have led to a renaissance in quantum optical interferometry. Optical interferometry has been used to test the foundations of quantum mechanics and implement some of the novel ideas associated with quantum entanglement such as quantum teleportation, quantum cryptography, quantum lithography, quantum computing logic gates, and quantum metrology. In this paper, we focus on the new ways that have been developed to exploit quantum optical entanglement in quantum metrology to beat the shot-noise limit, which can be used, e.g., in fiber optical gyroscopes and in sensors for biological or chemical targets. We also discuss how this entanglement can be used to beat the Rayleigh diffraction limit in imaging systems such as in LIDAR and optical lithography. View full abstract»

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  • Simplified BOTDA system based on Direct Modulation of a Laser Diode with an Extended Measurement Range

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2398 KB)  

    We demonstrate a simplified Brillouin optical time-domain analysis (BOTDA) system based on direct current modulation of a laser diode which is configured and optimized for long range measurement. A pre-compensated low-frequency RF wave is applied for time-division generation of Brillouin pump and probe waves without using any microwave device. Low-speed frequency dithering of the laser diode is additionally applied for the suppression of the coherent noise originating from Rayleigh scattering of the leakage probe wave. In experiments, distributed measurements of Brillouin frequency shift along a 25 km single-mode fiber are presented with a spatial resolution of 1.2 m and measurement accuracy (σ ) of 0.45 MHz, respectively. View full abstract»

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  • OFDM Allocation Optimization for Crosstalk Mitigation in Multiple Free-Space Optical Interconnection Links

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (398 KB)  

    The growing demand for high interconnection speed in next-generation computers is driving the technology-shift for communication from the electronic to the optic domain. One of the favored interconnection technologies for this task is the free-space optical interconnect (FSOI). FSOI technology uses laser links between computer components and provides a lower bound on propagation delay due to the low index of refraction of air, when compared with the indices common in waveguide technologies. FSOIs based on DC-biased optical orthogonal frequency-division multiplexing (DCO-OFDM) may provide excellent data throughput in intensity modulation/direct detection (IM/DD) systems. However, the main drawback limiting the implementation of FSOIs is the inevitable trade-off between interconnection density and the crosstalk level, resulting from the diffraction effect and from optical misalignment. The purpose of this paper is to promote improved interconnection density of such FSOIs by use of inherent DCO-OFDM resource allocation capabilities. The crosstalk-resulted interference was formulated as joint multi-link bit-and-power allocation optimization. The theoretical analysis reveals general guidelines for dense FSOI. Further, a reduced-complexity numerical sub-optimal algorithm for joint multi-link bit-and-power allocation was proposed. The simulation results show that the proposed suboptimal algorithm outcome is close to the theoretical optimal performance. View full abstract»

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Aims & Scope

The Journal of Lightwave Technology contains articles on current research, applications and methods used in lightwave technology and fiber optics.

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Editor-in-Chief
Peter J. Winzer
Alcatel-Lucent Bell Labs