Showing papers on "Dispersion-shifted fiber published in 1998"
TL;DR: A method of measuring strain over 30-cm intervals to an accuracy of10 microstrain in unaltered low-loss communications-grade single-modeoptical fiber is presented.
Abstract: A method of measuring strain over 30-cm intervals to an accuracy of10 microstrain in unaltered low-loss communications-grade single-modeoptical fiber is presented. The method uses a tunable external cavity diode laser to measure the reflected intensity of a reflector-fiber system as a function of wavelength. This measurement is performed with no strain applied to the fiber to produce a reference and then again after a strain has been induced. Cross correlation of the Rayleigh scatter spectra from a selected section of fiber in the strained and unstrained states determines the spectral shift resulting from the applied strain.
635 citations
TL;DR: In this paper, the waveguiding properties of a new type of low-loss optical waveguide have been reported, where the photonic crystal fiber can be engineered to support the fundamental guided mode at every wavelength within the transparency window of silica.
Abstract: We report on the waveguiding properties of a new type of low-loss optical waveguide. The photonic crystal fiber can be engineered to support only the fundamental guided mode at every wavelength within the transparency window of silica. Experimentally, a robust single mode has been observed over a wavelength range from 337nm to beyond 1550nm (restricted only by available wavelength sources). By studying the number of guided modes for fibers with different parameters and the use of an effective index model we are able to quantify the requirements for monomode operation. The requirements are independent of the scale of the fiber for sufficiently short wavelengths. Further support for the predictions of the effective index model is given by the variation of the spot size with wavelength,
411 citations
TL;DR: The dispersion properties of photonic crystal fibers are calculated by expression of the modal field as a sum of localized orthogonal functions to derive uniform dispersion values for single mode and double mode fibers.
Abstract: The dispersion properties of photonic crystal fibers are calculated by expression of the modal field as a sum of localized orthogonal functions. Even simple designs of these fibers can yield zero dispersion at wavelengths shorter than 1.27 µm when the fibers are single mode, or a large normal dispersion that is suitable for dispersion compensation at 1.55 µm.
375 citations
TL;DR: A novel application of a wavelength-swept fiber laser to fiber Bragg grating sensor-array interrogation and static-dynamic strain measurements with a resolution of 0.47mu?
Abstract: We demonstrate a novel application of a wavelength-swept fiber laser to fiber Bragg grating sensor-array interrogation. The laser provides high signal powers of >3 mW with <0.1-nm spectral resolution over a 28-nm wavelength span. Using time-interval counting, we demonstrate static-dynamic strain measurements with a resolution of 0.47mu? rms at a sampling rate of 250 Hz.
335 citations
TL;DR: In this paper, a periodic sine modulation of the refractive index profile in fiber Bragg gratings (FBGs) was demonstrated with multiple equally spaced and identical wavelength channels.
Abstract: Through a periodic sine modulation of the refractive index-profile in fiber Bragg gratings (FBGs), we demonstrate gratings with multiple equally spaced and identical wavelength channels. We show 10-cm-long gratings with 4, 8, and 16 identical uniform wavelength channels separated by the ITU spacing of 100 GHz and a 22.5-cm-long grating with four identical dispersion compensating channels with a 200-GHz separation designed to dispersion compensate 80-km data transmission through standard fiber at 1.55 /spl mu/m.
329 citations
TL;DR: The signal-gain characteristics of tellurite-based erbium-doped fiber amplifiers are clarified based on spectroscopic properties and signal- gain measurements.
Abstract: The signal-gain characteristics of tellurite-based erbium-doped fiber amplifiers are clarified based on spectroscopic properties and signal-gain measurements. The potential of tellurite-based erbium-doped fiber for use as a broadband light source is also described.
261 citations
TL;DR: In this paper, the properties and fiber dependence of distributed Raman pre-amplifiers and the effects of Rayleigh backscattering, which limits the sensitivity improvements that can be realized, are discussed.
Abstract: The properties and fiber dependence of distributed Raman pre-amplifiers and, in particular, the effects of Rayleigh backscattering, which limits the sensitivity improvements that can be realized, is discussed. Bit-error-rate (BER) measurements show improvements In the effective receiver sensitivity of 6.2 and 7.0 dB for dispersion shifted fiber (DSF) and silica-core fiber (SCF), respectively. Theoretical predictions of the effective noise figure based on measured fiber parameters indicate improvements of 6.6 dB for DSF and 7.4 dB for SCF in good agreement with the measured optical SNR. The optimum receiver sensitivity is obtained in DSF with less than 600 mW of pump power, whereas the 0.8-dB superior performance of the SCF requires approximately 1 W.
230 citations
TL;DR: In this paper, the effect of random fluctuations in the zero-dispersion wavelength is considered for fiber four-wave mixing and theoretical expressions for average parametric gain, phase-conjugation conversion efficiency, and gain bandwidth are obtained and found to be in good agreement with experiments.
Abstract: The effect of random fluctuations in the zero-dispersion wavelength is considered for fiber four-wave mixing. Theoretical expressions for average parametric gain, phase-conjugation conversion efficiency, and gain bandwidth are obtained and found to be in good agreement with experiments. Possible limitations on the noise figure in phase-sensitive amplifiers based on fiber four-wave mixing are also discussed.
207 citations
TL;DR: In this paper, a tellurite-based Er/sup 3+/-doped fiber amplifier (EDFA) with a flat amplification bandwidth of 76 nm and a noise figure of less than 7 dB was described.
Abstract: We describe a tellurite-based Er/sup 3+/-doped fiber amplifier (EDFA) with a flat amplification bandwidth of 76 nm and a noise figure of less than 7 dB. Furthermore, a parallel-type amplifier composed of this EDFA and a 1.45-/spl mu/m-band Tm/sup 3+/-doped fluoride fiber amplifier achieved a flat amplification bandwidth of 113 nm.
182 citations
Patent•
17 Aug 1998TL;DR: In this paper, a single mode optical waveguide fiber having a core refractive index profile in which the profile parameters are selected to provide an attenuation minimum is presented, and a set of profiles having the same general shape and dimensions is shown to have a group of profiles contained in a sub-set which exhibit a minimum of attenuation as compared to the remaining members of the set.
Abstract: Disclosed is a single mode optical waveguide fiber having a core refractive index profile in which the profile parameters are selected to providean attenuation minimum. A set of profiles having the same general shape and dimensions is shown to have a group of profiles contained in a sub-set which exhibit a minimum of attenuation as compared to the remaining members of the set. The members of the sub-set have been found to have the lowest effective group index, n geff, and the lowest change in .beta.2 under waveguide fiber bending.
181 citations
TL;DR: In this article, a theoretical analysis of the pump-induced temperature change and associated thermal phase shift occurring in a pumped doped fiber is presented, both in the dynamic and steady-state regimes.
Abstract: A theoretical analysis of the pump-induced temperature change and associated thermal phase shift occurring in a pumped doped fiber is presented. Although the primary devices targeted are all-optical switches based on doped fibers, where such effects can be detrimental, this analysis is also applicable to lasers, amplifiers, and other doped fiber devices. The effects of a single pump pulse, multiple pulses and continuous wave (CW) pumping are investigated, both in the dynamic and steady-state regimes. Simple expressions are derived for the thermal relaxation time constant of a fiber, and for its steady-state temperature rise and thermal phase shift under CW pumping. This study predicts that in all-optical fiber switches utilizing a reasonably good dopant the thermal effect due to a single short pulse is negligible in all interferometers, while the steady-state effect can be sizable in a standard fiber Mach-Zehnder but is negligible in a twin-core fiber, a two-mode fiber, and a specially designed Mach-Zehnder interferometer.
TL;DR: In simulations of a Yb(3+) -doped Fiber laser, ring doping increased the slope efficiency to 62%, up from 13% for a conventional core-doped fiber, and made the laser less sensitive to quenching of the laser-active dopant and to excited-state absorption of the lasing field.
Abstract: We propose and theoretically analyze three-level cladding-pumped fiber lasers in which the laser-active dopant is placed in a ring around a single-mode core. A ring-doped laser can work efficiently at wavelengths with strong small-signal absorption. This is otherwise difficult in a cladding-pumped fiber. Moreover, ring doping makes the laser less sensitive to quenching of the laser-active dopant and to excited-state absorption of the lasing field. In simulations of a Yb3+-doped fiber laser, ring doping increased the slope efficiency to 62%, up from 13% for a conventional core-doped fiber.
TL;DR: Self-pulsations detected in the output from the double-clad fiber laser may indicate the presence of ion-clustering effects.
Abstract: The operation of a diode-pumped Tm-doped silica fiber laser that uses the cladding-pumping arrangement to produce high-power cw output at wavelengths near 2 µm is reported. We obtained a maximum output power of 5.4 W at a slope efficiency of 31% with respect to the launched pump power at a total optical-to-optical efficiency of 22%. The fiber-laser output wavelength was tuned between 1.880 and 2.033 µm by adjustment of the fiber length, with >4 W of power obtainable from 1.94 to 2.01 µm. Self-pulsations detected in the output from the double-clad fiber laser may indicate the presence of ion-clustering effects.
TL;DR: In this paper, the dispersion characteristics of apodized, linearly chirped fiber Bragg gratings and their potential as dispersion compensators have been studied systematically, and it is shown that the positive hyperbolic-tangent profile results in an overall superior performance, as it provides highly linearized time-delay characteristics with minimum reduction in the linear dispersion.
Abstract: The dispersion characteristics of apodized, linearly chirped fiber Bragg gratings and their potential as dispersion compensators have been studied systematically. It is shown that the positive hyperbolic-tangent profile results in an overall superior performance, as it provides highly linearized time-delay characteristics with minimum reduction in the linear dispersion. To compensate for the linear dispersion of 100 km of standard telecom fiber over certain bandwidth (in nanometers), the required grating length is 19.24 cm/nm.
TL;DR: It is demonstrated that appropriately designed doped multimode fibers provide robust single-mode output when used within a fiber laser cavity, and offers significant scope for extending the range of single- mode output powers and energies that are achievable from fiber-laser-amplifier systems.
Abstract: We demonstrate that appropriately designed doped multimode fibers provide robust single-mode output when used within a fiber laser cavity. Using a novel large-mode-area fiber, we demonstrate what we believe to be record single-mode M2 0.5 mJ from a Q-switched fiber laser and even higher pulse energies (as high as 0.85 mJ) with slightly compromised spatial-mode quality M2<2.0. This approach offers significant scope for extending the range of single-mode output powers and energies that are achievable from fiber-laser–amplifier systems.
TL;DR: A novel, sensitive, simple, and robust strain interrogation technique is analyzed and experimentally tested, which achieves high dynamic strain sensitivity of 45 picostrain/ radicalHz rms at 3 kHz.
Abstract: A novel, sensitive, simple, and robust strain interrogation technique is analyzed and experimentally tested. By locking a laser wavelength to the midreflection wavelength of a standard fiber Bragg grating and measuring the error signal, we achieve high dynamic strain sensitivity of 45 picostrain/Hz rms at 3 kHz, where the dominant noise in the experiment is the laser frequency noise.
TL;DR: In this article, changes in coherence during the process of supercontinuum generation in a dispersion-shifted fiber (DSF) and DFF have been investigated in detail for the first time.
TL;DR: In this article, a spectrally efficient millimeter-wave (mm-wave) fiber-wireless transmission system is presented demonstrating downstream transportation of 155-Mb/s BPSK data at 38 GHz over 50 km of standard singlemode fiber and a 5m wireless link.
Abstract: A spectrally efficient millimeter-wave (mm-wave) fiber-wireless transmission system is presented demonstrating downstream transportation of 155-Mb/s BPSK data at 38 GHz over 50 km of standard single-mode fiber and a 5-m wireless link. The effect of fiber chromatic dispersion on the transmission of the mm-wave optical carrier was overcome by using a single dual-electrode Mach-Zehnder modulator to generate optical single-sideband (SSB) modulation with carrier. We also demonstrate a simple technique for obtaining electrical SSB that will allow the effect of fiber dispersion across the bandwidth of the information to be overcome with simple electrical delay equalization. We predict that this fiber-wireless system could permit the transportation of mm-wave signals with large bit rates over long optical fiber distances.
TL;DR: A novel cladding pumped Nd(3+) fiber laser operating in an enhanced Q-switched regime with a stable repetition rate is described and a peak power of 3.7 kW enhanced by an order of magnitude greater than that of conventional Q- Switched fiber devices is demonstrated.
Abstract: A novel cladding pumped Nd3+ fiber laser operating in an enhanced Q-switched regime with a stable repetition rate is described. By exploiting fiber nonlinearities in the laser cavity, we demonstrated a peak power of 3.7??kW enhanced by an order of magnitude greater than that of conventional Q-switched fiber devices. Pulse durations as short as 2??ns have been achieved.
TL;DR: In this paper, the effect of nonideal dispersion and reflection characteristics of chirped fiber gratings on the performance of 10-Gb/s non-return-to-zero-transmission systems operating over standard fiber is investigated.
Abstract: The effect of nonideal dispersion and reflection characteristics of chirped fiber gratings on the performance of 10-Gb/s nonreturn-to-zero-transmission systems operating over standard fiber is investigated. The system penalty for different amplitude and period ripples are quantified. Analyses of an experimental grating confirm that current fabrication technology can meet the requirements for <1-dB-penalty operation.
TL;DR: An all-fiber add-drop filter was developed and fabricated by recording a Bragg grating in the waist of an asymmetric mode converter-coupler formed by adiabatic tapering and fusing of two locally dissimilar, single-mode optical fibers.
Abstract: We developed and fabricated an all-fiber add–drop filter by recording a Bragg grating in the waist of an asymmetric mode converter–coupler formed by adiabatic tapering and fusing of two locally dissimilar, single-mode optical fibers. The insertion loss of the device was ~0.1 dB. A narrow spectral bandwidth ( 90%) were also demonstrated. In addition, the filter was polarization independent.
TL;DR: This work demonstrates nearly distortionless 2.5-km fiber transmission of sub-500-fs pulses, using a combination of standard single-mode fiber, dispersion-compensating fiber, and a programmable pulse shaper for simultaneous quadratic and cubic dispersion compensation.
Abstract: We demonstrate nearly distortionless 2.5-km fiber transmission of sub-500-fs pulses, using a combination of standard single-mode fiber, dispersion-compensating fiber, and a programmable pulse shaper for simultaneous quadratic and cubic dispersion compensation. The dispersion-compensating fiber corrects the bulk of the quadratic and the cubic phases for the single-mode fiber, and the fiber-pigtailed programmable pulse shaper exactly compensates the residual dispersion terms. Together these elements permit complete recompression of pulses, which first broaden by ?400 times in the single-mode fiber.
TL;DR: Using coupled-mode theory, a theoretical model shows that PMD can be reduced effectively by use of frequency-modulated spin profiles.
Abstract: Using coupled-mode theory, we develop a theoretical model to analyze the effects of fiber spin profiles on polarization mode dispersion (PMD). Constant, sinusoidal, and frequency-modulated spin profiles are examined, and phase-matching conditions are analyzed. Our analysis shows that PMD can be reduced effectively by use of frequency-modulated spin profiles.
TL;DR: In this article, the effects of introducing multiple phase shifts at various locations along a long-period fiber gratings (LPFG) were analyzed by the coupledmode theory together with the fundamental-matrix method.
Abstract: Phase-shifted long-period fiber gratings (LPFG's) are analyzed by the coupled-mode theory together with the fundamental-matrix method. The effects of introducing multiple phase shifts at various locations along a LPFG are highlighted. The results compare well with published experimental data.
TL;DR: In this paper, a method for controlling the chirp of a linearly chirped fiber Bragg grating (FBG) without a center wavelength shift by using beam bending was proposed.
Abstract: We propose a new method for controlling the chirp of a linearly chirped fiber Bragg grating (FBG) without a center wavelength shift by using beam bending. The beam consists of a plastic sleeve enclosing a 10-cm-long chirped FBG and a metal rod. The grating pitch could be varied to give positive or negative chirp as well as zero chirp (i.e. uniform pitch) as applying displacement to one end of the beam without rotation. The dispersion at the two extremes of mechanical displacement were -791 ps/nm and +932 ps/nm. The center wavelength shift of the FBG was as small as 0.09 nm over the dispersion tuning range.
Patent•
18 Aug 1998TL;DR: In this article, a remotely pumped erbium-doped fiber amplifier (EDFA) is de-tuned with respect to wavelength, the wavelength being selected longer than both the optimal wavelengths for pumping the EDFA and for producing Raman gain in the transmission fiber, respectively.
Abstract: The disclosed optical fiber communication system comprises a remotely pumped erbium-doped fiber amplifier (EDFA). The pump radiation is de-tuned with respect to wavelength, the wavelength being selected longer than both the optimal wavelengths for pumping the EDFA and for producing Raman gain in the transmission fiber, respectively. Such de-tuning results in improved over-all system performance through reduced multi-path interference. Exemplarily, the pump radiation has wavelength in the range 1490-1510 nm.
TL;DR: In this paper, a low-cost and compact wavelength division multiplexing scheme is demonstrated for achieving bit rates of 5 and 10 Gb/s through 300 and 100 m of 62.5/125/spl mu/m multimode fiber, respectively.
Abstract: Current local area network (LAN) bandwidth demands of >1 Gb/s are pushing the limit of the bandwidth-distance product of multimode fiber, the predominant fiber in LAN backbones. In order to overcome these limitations, a low-cost and compact wavelength division multiplexing scheme is demonstrated. Aggregate bit rates of 5 and 10 Gb/s are achieved through 300 and 100 m of 62.5/125-/spl mu/m multimode fiber, respectively. Four vertical-cavity surface-emitting lasers are used at wavelengths of 820, 835, 850, and 865 nm with each operating at a bit rate of 1.25 or 2.5 Gb/s. This technology provides a practical solution for reaching bit rates up to 10 Gb/s in the LAN.
01 Jan 1998
TL;DR: In this article, an all optical wavelength conversion of over 72 nm was achieved by four-wave mixing in a polarization- maintaining highly nonlinear dispersion-shijied fiber.
Abstract: An all optical wavelength conversion of over 72 nm is achieved by four-wave mixing in a polarization- maintaining highly nonlinear dispersion-shijied fiber. Simultaneous wavelength conversion and optical phase conjugation of 320 Gbls (32x10 Gbls) WDM signal between 1.55-jm band and 1.58-pm band is successfully demonstrated with a polarization-insensitive configuration.
Patent•
04 Sep 1998TL;DR: In this paper, the Fabry-Perot cavity of a fiber-optic laser with a gain medium, such as a semiconductor, half-cavity VCSEL, or an organic light emitting polymer, is described.
Abstract: This invention provides compact, fixed-wavelength and tunable fiber-optic lasers comprising a gain medium, for example a semiconductor, half-cavity VCSEL, or an organic light emitting polymer, within a Fabry-Perot cavity wherein one of the mirrors forming the cavity is a mirror integral with a fiber, for example a mirror (metallic or dielectric, for example) deposited at a fiber end, a reflective tap within an optical fiber, a fiber Bragg Grating (FBG), or a fiber loop mirror. Semiconductor gain material can be bulk semiconductor material or comprise a semiconductor multiple quantum well region. The gain medium itself is not confined to a fiber. The FP cavity of these lasers typically contains a thin active medium ranging up to about 10 μm in length, but more preferably about 1 to about 21 μm in thickness
TL;DR: In this paper, it has been made clear through model simulations that dispersion-flattened and decreasing fiber (DFDF) is one of the most suitable fibers for broadband supercontinuum (SC) generation.
Abstract: It has been made clear through model simulations that dispersion-flattened and decreasing fiber (DFDF) is one of the most suitable fibers for broad-band supercontinuum (SC) generation. SC generation In a bandwidth of 280 nm with intensity fluctuation less than 15 dB has been experimentally observed by using the DFDF designed and manufactured with an optimized dispersion profile.