Showing papers in "Journal of Lightwave Technology in 1994"
TL;DR: In this article, the optical bandwidth and fabrication tolerances of MMI couplers were derived for strong guided structures, and they were shown to be inversely proportional to the number of input and output ports and the length of the device.
Abstract: Analytical expressions are derived which relate the optical bandwidth and the fabrication tolerances of multimode interference (MMI) couplers to their most important design parameters. These expressions compare adequately with mode analysis simulations. For strong guided structures, the optical bandwidth is shown to he inversely proportional to the number of input and output ports N and to the length of the device. The fabrication tolerances are independent of N and proportional to the output channel separation D. Measurements on MMI couplers in InP/InGaAsP corroborate the theoretical predictions. >
314Â citations
TL;DR: In this article, a theoretical analysis of the self-mixing interference produced by an external optical feedback is found to be due to the variations in the threshold gain and in the spectral distribution of the laser output.
Abstract: This paper presents a theoretical analysis and a comparison with experimental results on self-mixing interference inside a single-longitudinal-mode diode laser. A theoretical model, based on the steady-state equations of the lasing condition in a Fabry-Perot type laser cavity, is described, and through it a satisfactory analysis of self-mixing interference for optical sensing applications is given. In this work, the self-mixing interference produced by an external optical feedback is found to be due to the variations in the threshold gain and in the spectral distribution of the laser output. The gain variation results in an optical intensity modulation, and the spectral variation determines both the modulation waveform and the coherence properties of the interference. The theoretical analysis of the self-mixing interference is seen to yield a simulation of the laser power modulation which is in good agreement with the experiment results reported. >
310Â citations
TL;DR: In this article, the temperature dependence of chromatic dispersion at any wavelength from UV to 1.7 nm/m was investigated for fused silica (SiO/sub 2/), aluminosilicate, and Vycor glasses.
Abstract: Temperature-dependent Sellmeier coefficients are necessary to optimize optical design parameters of the optical fiber transmission system. These coefficients are calculated for fused silica (SiO/sub 2/), aluminosilicate, and Vycor glasses for the first time to find the temperature dependence of chromatic dispersion at any wavelength from UV to 1.7 /spl mu/m. The zero dispersion wavelength /spl lambda//sub 0/ (1.273 /spl mu/m for SiO/sub 2/, 1.393 /spl mu/m for aluminosilicate, and 1.265 /spl mu/m for Vycor glasses at 26/spl deg/C) varies linearly with temperature, and d/spl lambda//sub 0//dT is 0.03 nm/K for aluminosilicate and Vycor glasses, whereas for SiO/sub 2/ it is 0.025 nm/K. This study interprets the recently observed experimental value of d/spl lambda//sub 0//dT for two dispersion shifted optical fibers; and the dominantly material origin of d/spl lambda//sub 0//dT is confirmed here as a fundamental property of the optical fiber glasses. >
307Â citations
TL;DR: In this paper, the polarization properties of stimulated brillouin scattering (SBS) in low birefringent optical fibers were evaluated using Stokes calculus, and it was found that the Brillouin gain for orthogonally polarized pump and probe wave is half (in dB) of the gain for identical polarization, and not equal as often mentioned in literature.
Abstract: The polarization properties of stimulated brillouin scattering (SBS) in low birefringent optical fibers were evaluated using Stokes calculus. It was found that the Brillouin gain for orthogonally polarized pump and probe wave is half (in dB) of the gain for identical polarization, and not equal as often mentioned in literature. Therefore the polarization factor is K=1/sub 1/2/ for complete polarization scrambling, and not K=2. The spontaneous SBS has the same state of polarization as the pump, and its degree of polarization is 33.3% for low pump powers and near 100% for high pump powers. The experimental results agree very well with the calculations. >
283Â citations
TL;DR: In this article, the effects of mode hopping in the optical-frequency sweep are compared to numerical simulations and a simple formula to predict the position of spurious peaks due to mode hopping is presented.
Abstract: Experimental and theoretical investigations of coherent optical-frequency-domain reflectometry using semiconductor laser sources are presented. Good agreement was found between the analysis of the signal-to-noise ratio due to the phase noise and the experimental results. The sensitivity limit due to the quantum noise is also described. Limitations due to the nonlinearity in the optical frequency sweep produced by the thermal-response time of the laser and mode hopping are investigated and compared with experimental results. Two interferometric methods to characterize the thermal-response time of the laser and their implementations are described. The effects of mode hopping in the optical-frequency sweep are compared to numerical simulations. A simple formula to predict the position of spurious peaks due to mode hopping are presented. A spatial resolution of 400 /spl mu/m over 10 cm was obtained by correcting the nonlinearity in the optical-frequency sweep by using an auxiliary interferometer. The Rayleigh backscattering was observed for the first time over more than 400 m of fiber using a DFB laser coupled to an external cavity. >
254Â citations
TL;DR: In this article, the extrema density and mean-level crossing densities of a single-mode fiber were derived for the measurement of the expected value of polarization-mode dispersion (PMD) in the transmission spectrum.
Abstract: Routine characterization of polarization-mode dispersion (PMD) in single-mode fiber, both at the manufacturing stage and in installed systems, requires an easy-to-implement measurement technique. One method that is particularly simple to implement involves counting the number of extrema (i.e., maxima and minima) per unit wavelength interval in the transmission spectrum measured through a polarizer (analyzer) placed at the output of a test fiber. In this paper, we establish accurate equations relating both the extrema density and mean-level crossing densities in such spectra to the expected value of PMD. These equations are used to measure several fiber samples, and are compared to measured values obtained with a commercially available test set. It is shown that measuring both mean-level crossings and extrema densities provides a simple means for establishing whether a fiber is scaling as /spl radic/L (long-length regime) or L (short-length regime). Using Monte Carlo simulations, the accuracy of the fixed-analyzer measurements is examined as a function of the width of the wavelength interval over which measurements are made. In addition, the simulations indicate that fixed-analyzer measurements are quite robust with respect to the presence of polarization-dependent loss (PDL) in the span, an important consideration for measurements in amplified systems. >
233Â citations
TL;DR: In this paper, a spatial mode-converter is used to selectively excite a higher order mode in specially designed multimode fiber, which can be used to compensate the positive dispersion in conventional single-mode fiber spans.
Abstract: Higher order spatial modes in optical fibers exhibit large, negative chromatic dispersion when operated near their cutoff wavelength. By using a spatial mode-converter to selectively excite a higher order mode in specially designed multimode fiber, this dispersion can be used to compensate the positive dispersion in conventional single-mode fiber spans. In this paper, issues related to compensating fiber and mode-converter design are explored. Experimental measurements in specially designed two-mode fibers operated in LP/sub 11/ mode show negative dispersion as large as -70 ps/nm/spl middot/km at 1555 nm. Pulse propagation and system experiments employing spatial mode-converters to excite LP/sub 11/ mode in a two-mode fiber demonstrate the feasibility of this technique for dispersion compensation in lightwave systems. >
233Â citations
TL;DR: In this article, the characteristics of 1.55 /spl mu/m Er-doped superfluorescent fiber sources (SFSs) intended for fiber-optic gyroscope (FOG) applications are explored theoretically and experimentally.
Abstract: The characteristics of 1.55 /spl mu/m Er-doped superfluorescent fiber sources (SFS's), intended for fiber-optic gyroscope (FOG) applications, are explored theoretically and experimentally. With proper selection of the source configuration, fiber length, pump wavelength, pump power, and fiber composition, we show that it is possible to meet the stringent requirements of the FOG, including a high output power, broad emission bandwidth, and excellent spectral thermal stability. Variations of the mean wavelength, spectral width, and output power of the SFS with fiber length, pump power, pump wavelength, and temperature are modeled for representative sources pumped near 980 nm or 1.48 /spl mu/m, and are shown to be in good agreement with experimental results. The effects of a multimoded pump, erbium ion pair, and optical feedback are also assessed. This study indicates that the Er-doped SFS is an excellent candidate for the FOG and for other applications requiring spatial coherence and low temporal coherence. >
226Â citations
TL;DR: In this paper, the design, fabrication and characterization of a traveling wave Ti:LiNbO/sub 3/Mach-Zehnder interferometric modulator are discussed, and the dependence of the velocity match condition on electrode thickness and wall angle is demonstrated experimentally and with finite element calculations.
Abstract: The design, fabrication and characterization of a traveling wave Ti:LiNbO/sub 3/ Mach-Zehnder interferometric modulator are discussed. The dependence of the velocity match condition on electrode thickness and wall angle is demonstrated experimentally and with finite element calculations. A set of test electrode structures is fabricated to study electrical losses in the modulator electrode. Loss coefficients are assigned to different sections of the device, and dielectric and radiative losses are shown to play an important role at high frequencies. This information is used in conjunction with finite-element calculations to develop accurate models for both the electrical and optical responses. The frequency dependence of the half-wave voltage is measured and shown to be in good agreement with a model. >
223Â citations
TL;DR: In this article, the effect of rib etch depth, width, and interface roughness on loss and mode characteristics have been studied at wavelengths of 1.15 and 1.523 microns.
Abstract: Optical rib waveguides with rib heights of 3.17 and 7.67 microns with various widths have been formed in separation by implantation of oxygen (SIMOX) based silicon-on-insulator (SOI) structures. The effect of waveguide rib etch depth, width, and interface roughness on loss and mode characteristics have been studied at wavelengths of 1.15 and 1.523 microns. The experimental results support the hypothesis that certain rib dimensions can lead to single mode SOI waveguides even though planar SOI waveguides of similar multimicron dimension are not single mode. Mode loss was found to be strongly dependent on interface roughness and mode confinement. >
199Â citations
TL;DR: In this paper, the advantages of a radio-based final drop for video delivery are outlined and spectral availability constraints that lead to the identification of the mm-wave region of the radio spectrum as the most appropriate for this application are discussed.
Abstract: Advantages of a radio-based final drop for video delivery are outlined and spectral availability constraints that lead to the identification of the mm-wave region of the radio spectrum as the most appropriate for this application are discussed. The possibility of simultaneously supporting other broadband services, such as B-ISDN and traffic information systems (IVHS), enhance the attractiveness of a radio link. A large number of antenna units need to be served due to the limited propagation distances achievable at mm-wave frequencies, and therefore, a low-cost generation and delivery method has to be developed. In this paper, alternatives for the optical generation and distribution of mm-wave signals are reviewed and a new method is proposed that eases the bandwidth, and hence the cost, of the required optoelectronic components. An assessment of the relative merits of the methods is given. >
TL;DR: In this article, a vector finite element method with the high-order mixed-interpolation-type triangular elements is described for the analysis of optical waveguiding problems, which is a combination of linear edge elements for transverse components of the electric or magnetic field and quadratic nodal elements for the axial one.
Abstract: A vector finite element method with the high-order mixed-interpolation-type triangular elements is described for the analysis of optical waveguiding problems. It is a combination of linear edge elements for transverse components of the electric or magnetic field and quadratic nodal elements for the axial one. The use of mixed-interpolation-type elements provides a direct solution for propagation constants and avoids spurious solutions. This approach can yield more accurate results compared with the conventional approach using the lowest order mixed-interpolation-type elements, namely, constant edge elements and linear nodal elements. The accuracy of this approach is investigated by calculating the propagation characteristics of optical rib waveguides. Results obtained for both E/sup x/ and E/sup y/ polarizations are validated using benchmark results produced by established methods. >
TL;DR: In this paper, a finite-difference approach was proposed to obtain a unique set of equations for dielectric optical waveguides with stepped refractive index profiles, where the boundary conditions were formulated and included in the finite difference scheme.
Abstract: An important class of dielectric optical waveguides has stepped refractive index profiles. For these waveguides we present a new finite-difference approach free of spurious modes. The coupled difference equations are formulated in terms of the transverse magnetic field components H/sub x/ and H/sub y/. We show how the boundary conditions can be formulated and included in the finite difference scheme to obtain a unique set of equations. For a step-index fiber a comparison of the numerical results with the analytical solution shows that the relative error in the propagation constant is as low as 4.4/spl times/10/sup /spl minus/7/ for an index difference of 7.3%. For a rib waveguide, we compare our results with previously published data based on other methods. Field plots of the dominant and the weak transverse field components of the magnetic field for the fundamental mode of a buried rib waveguide are also given. >
TL;DR: Discretely tunable filter, receiver, and laser devices based on the integration of wavelength router/multiplexers withactive elements with active elements are proposed.
Abstract: Discretely tunable filter, receiver, and laser devices based on the integration of wavelength router/multiplexers with active elements are proposed. Each of these functions has been demonstrated experimentally in integrated form in InGaAsP, and will be published elsewhere. Such devices are key elements in WDM networks. >
TL;DR: In this paper, the authors analyzed the operation of a reset-free polarization controller comprising three endlessly rotatable wave plates: a first quarter wave plate followed by a half-wave plate and a second quarter waveplate rotated synchronously with the first wave plate.
Abstract: We analyze the operation of a reset-free polarization controller comprising three endlessly rotatable wave plates: a first quarter-wave plate followed by a half-wave plate and a second quarter-wave plate, which is rotated synchronously with the first quarter-wave plate We show that for any arbitrary angular offset between the two quarter-wave plates; the controller allows continuous, reset-free transformations from any varying general input state of polarization into any general output state An integrated-optic realization of this scheme on z-propagation LiNbO/sub 3/ offers control speeds that well exceed the speed of natural polarization fluctuations in standard single-mode fibers, thus allowing fast automatic polarization stabilization in fiber-optic transmission systems >
TL;DR: The influence of fiber four-wave mixing on multichannel transmissions is investigated in this article, where the power penalty is not uniquely determined by the crosstalk level for CW lights, depending on the demodulation scheme and channel spacing, especially in the zero-dispersion wavelength region.
Abstract: The influence of fiber four-wave mixing on multichannel transmissions is investigated We present strict and approximate theoretical treatments for evaluating power penalty with intensity-modulated/direct-detection (IM/DD) and FSK/direct detection A comparison of calculations shows that both methods yield the same result in the small penalty region Using these treatments, power penalty and allowable fiber input power are derived for various system conditions It is shown that the power penalty is not uniquely determined by the crosstalk level for CW lights, depending on the demodulation scheme and channel spacing, especially in the zero-dispersion wavelength region >
TL;DR: In this article, the characteristics of a 28-channel multiplexer based on an arrayed-waveguide grating were investigated by using the grating theory and related experiments and the measured minimum loss is 4.2 dB, which is composed of 3.4 dB excess loss and 0.8 dB grating loss.
Abstract: The characteristics of a wavelength multiplexer based on an arrayed-waveguide grating are carefully investigated by using the grating theory and related experiments. A 28-channel multiplexer is designed and fabricated as SiO/sub 2/-Ta/sub 2/O/sub 5/ waveguides on a 1 cm/spl times/2 cm substrate. The designed wavelength channel spacing of 1 nm is obtained. The crosstalk to an adjacent channel is -15 dB. The measured minimum loss is 4.2 dB, which is composed of 3.4 dB excess loss and 0.8 dB grating loss. >
TL;DR: In this article, the authors show that cross-phase modulation does not limit the number of wavelength channels that a single optical fiber can support, and that even a moderate amount of dispersion tends to cancel out the influence of cross phase modulation, so that beyond a certain wavelength spacing, additional channels do not interfere with the channel under consideration.
Abstract: The phase term appearing in the expression for cross-phase modulation due to the optical Kerr effect depends on the sum of the powers carried by each wavelength channel. For this reason, one might expect that the amount of cross-phase modulation would increase with increasing channel number, causing increased interference among channels and hence limiting the total number of channels that a WDM system can support. However, computer simulations of multichannel systems have shown no change in signal distortion as the number of wavelength channels is increased from four to eight. In a simulated three-channel system, the signal distortion of the central channel approaches that of a single-channel system as the wavelength separation is increased to approximately 2 nm. Thus, even a moderate amount of dispersion tends to cancel out the influence of cross-phase modulation, so that beyond a certain wavelength spacing, additional channels do not interfere with the channel under consideration. From these observations, we conclude that cross-phase modulation does not limit the number of wavelength channels that a single optical fiber can support. However, self- and cross-phase modulation are not the only nonlinear effects influencing fiber lightwave systems. Stimulated Raman scattering tends to transfer optical power from short-wavelength channels to channels operating at longer wavelength, degrading their signal-to-noise ratio. The efficiency of this process increases with increasing wavelength spacing. Clearly, a compromise needs to be reached between the conflicting requirements imposed by the optical Kerr effect and by stimulated Raman scattering. >
TL;DR: In this paper, the authors describe polarization independent wavelength conversion, utilizing fiber four-wave mixing, by using two orthogonal pump lights having different frequencies, the baseband signal of the wavelength converted light is insensitive to the polarization state of the original signal light.
Abstract: This paper describes polarization independent wavelength conversion, utilizing fiber four-wave mixing. By using two orthogonal pump lights having different frequencies, the baseband signal of the wavelength converted light is insensitive to the polarization state of the original signal light. Experiments that include bit error measurements confirm the polarization independent operation. >
TL;DR: In this paper, the performance of coherent analog optical links employing amplitude modulation (AM), phase modulation (PM), and frequency modulation (FM) is compared to that of AM direct-detection (DD) links.
Abstract: We investigate the performance of coherent analog optical links employing amplitude modulation (AM), phase modulation (PM), and frequency modulation (FM). The performance of these coherent links is compared to that of AM direct-detection (DD) links. The signal-to-noise ratios, nonlinearities, and-spurious-free dynamic ranges (SFDR's) of the foregoing links are evaluated. We calculate the SFDR for links using DFB and Nd:YAG lasers with typical linewidths of 10 MHz and 5 kHz, respectively. The performance of PM and FM links is dominated by phase noise above a critical value of received optical power. For a linewidth of 10 MHz, and SFDR's of PM and FM links are 30 and 31 dB, respectively, for a received optical power above -27 dBm in a 1 GHz bandwidth. For a linewidth of 5 kHz, the corresponding SFDR's above a received power level of 0 dBm are 51 and 53 dB. The performance of DD and AM links is dominated by RIN above a critical value of received optical power. For a RIN level of -155 dB/Hz, the SFDR's of DD and AM links are 49 and 47 dB, respectively, for a received optical power of 10 dBm in a 1 GHz bandwidth. The SFDR's of the DD and coherent links used for transmission of subcarrier-multiplexed (SCM) signals are also derived. We evaluate target laser parameters needed by a number of different applications. For AM video and antenna remoting applications, linewidths of >
TL;DR: In this article, a coherent self-heterodyne detection system employing a recently proposed frequency translator, a DFB laser diode, and erbium-doped fiber amplifiers is demonstrated.
Abstract: Time domain reflectometry of spontaneously Brillouin scattered lightwaves in a single-mode optical fiber is demonstrated with a coherent self-heterodyne detection system employing a recently proposed frequency translator, a DFB laser diode, and erbium-doped fiber amplifiers. Since the probe pulse frequency is up-converted by the translator by an amount approximately equal to the Brillouin frequency shift, the self-heterodyne beat frequency can be reduced to a sufficiently low frequency in the IF band. The system enables one-end measurement of the Brillouin frequency shift distribution in optical fibers with a single way dynamic range (SWDR) of 16 dB and a frequency resolution of 5 MHz for a spatial resolution of 100 m. >
TL;DR: In this article, the authors proposed a method of dispersion-supported transmission of 10 Gb/s signals at 1.53 /spl mu/m wavelength on standard single-mode fiber with zero dispersion.
Abstract: Using the new method of dispersion-supported transmission, 10 Gb/s signals at 1.53 /spl mu/m wavelength are transmitted on standard single-mode fiber with zero dispersion at 1.3 /spl mu/m via the record length of 253 km without in-line regeneration. Detailed experiments with a directly modulated laser demonstrate the system performance for different fiber lengths ranging from 0 up to 253 km. >
TL;DR: In this article, an enhanced performance version of a high-speed burstmode compatible optical receiver and its application to 622-Mb/s optical bus operation in conjunction with an instantaneous clock recovery scheme is described.
Abstract: This paper describes an enhanced performance version of a high-speed burst-mode compatible optical receiver and its application to 622-Mb/s optical bus operation in conjunction with an instantaneous clock recovery scheme. The receiver is fabricated in a 12 GHz f/sub t/ silicon bipolar technology and consists of a differential transimpedance amplifier with an auto-threshold level controller and a high-speed quantizer. Using an InGaAs avalanche photodiode, the typical burst mode sensitivity is around /spl minus/34 dBm (10/sup /spl minus/9/ BER) at bit rates up to 1.5 Gb/s with a dynamic range of 26 db for both pseudorandom and burst signals. The results using a laser beam modulated by a high-speed external modulator indicate that the receiver can be operated at bit rates higher than 2 Gb/s. With a worst-case self-resetting time >
TL;DR: Polarimetric and two-mode differential interferometric schemes incorporated in an elliptical core fiber are able to resolve strain and temperature simultaneously with resolutions of 10 /spl mu/m/m and 5/spl deg/C, respectively.
Abstract: Polarimetric and two-mode differential interferometric schemes incorporated in an elliptical-core fiber are able to resolve strain and temperature simultaneously with resolutions of 10 /spl mu/m/m and 5/spl deg/C, respectively. A technique, based on the evaluation of the condition number of a matrix, is shown to be useful in evaluating comparative merits of multiparameter sensing schemes. The determinant of the beat length matrix is expressed in terms of mode propagation constants, and a method for designing specialized fibers suitable for simultaneous measurement of strain and temperature is proposed. Experimental results for four fibers are presented and cross-sensitivity issues are discussed. >
TL;DR: In this article, the influence of light injection on the reduction of the dynamical linewidth broadening of directly current-modulated semiconductor lasers at high bit rates is theoretically investigated and experimentally verified for 10 Gb/s NRZ pseudorandom modulation with a large current swing of 40 mA pp.
Abstract: The influence of strong light injection on the reduction of the dynamical linewidth broadening of directly current-modulated semiconductor lasers at high bit rates is theoretically investigated and experimentally verified for 10 Gb/s NRZ pseudorandom modulation with a large current swing of 40 mA pp. Significant chirp reduction and single-mode operation are observed for bulk DFB, quantum well DFB lasers at 10 Gb/s and a weakly coupled bulk DFB laser at 8 Gb/s, so that an improvement of the transmission performance using standard monomode fibers in the 1.55 /spl mu/m low-loss wavelength region can be achieved for all these laser types, where dispersion otherwise causes severe penalties for long-haul transmission. The properties of injection-locked bulk DFB and quantum well DFB lasers with respect to high bit rate modulation have been systematically studied by the use of the rate equation formalism. A dynamically stable locking range of more than 30 GHz under modulation has been found for both laser types with injection ratios higher than 0.5. >
TL;DR: In this paper, an optical parallel information processing technique adopting synthesis of the optical coherence function by using direct frequency modulation of a laser diode was proposed, which has no mechanical moving part, and there is no need for calculation by combining with holographic method.
Abstract: We propose an optical parallel information processing technique adopting synthesis of the optical coherence function by using direct frequency modulation of a laser diode. The optical coherence function having a delta-function-like shape can be synthesized by modulating the laser frequency with an appropriate waveform. In this optical parallel information processing system, selective extraction of two-dimensional information from a three-dimensional semitransparent object, and other operations between two-dimensional information, can be carried out. This manner has no mechanical moving part, and there is no need for calculation by combining with holographic method. In this paper, the method to synthesize the optical coherence function is studied in detail. The manner to improve the suppression ratio of unnecessary subpeaks in the delta-function-like coherence function is studied both in theory and experiments. Moreover, notch-shaped optical coherence function is also studied. Selective extraction and selective masking of a two-dimensional information from a three-dimensional object was successfully performed in basic experiments. >
TL;DR: In this article, the authors measured the finesse of a high Q resonator and used it for the first time with a stable Er/sup +3/ fiber grating laser source which was thermally tuned.
Abstract: Phosphorus doped silica on silicon waveguide propagation loss, bend loss and their polarization dependence have been measured using a set of different radii ring resonators. For a 30 mm ring radius a finesse of 132 was measured and the inferred propagation loss was 0.85 dB/m, the lowest value yet reported. To characterize the finesse of the high Q resonator we proposed and used for the first time a stable Er/sup +3/ fiber grating laser source which was thermally tuned. This configuration provides improved and accurate measurements capability for finesse values in the range well beyond 100. >
TL;DR: In this article, the effect of Kerr nonlinearity and noise of the erbium amplifiers was investigated in a link in which dispersion is zero to all orders, and analytical expressions for the error probability at the receiver were found for a differential phase shift keying modulation format.
Abstract: The effect of Kerr nonlinearity and noise of the erbium amplifiers is investigated in a link in which dispersion is zero to all orders. The analytical expressions for the error probability at the receiver are found for a differential phase shift keying modulation format. The role of the total bandwidth of the amplified spontaneous emission noise is discussed. >
TL;DR: In this article, a compensation technique based on propagating the signals through a specially designed fiber with large negative dispersion for the LP/sub 01/mode, thereby ending up with zero net pulse spreading is presented.
Abstract: The practical implementation of erbium-doped fiber amplifiers with gain at 1.55 /spl mu/m allows long unrepeatered transmission distances. However, in order to realize high data rates over these distances with already installed standard single mode fiber, techniques must be found to overcome the pulse spreading due to the positive chromatic dispersion of the transmission fiber in this window, we review a compensation technique based on propagating the signals through a specially designed fiber with large negative dispersion for the LP/sub 01/ mode, thereby ending up with zero net pulse spreading. The basis of the concept are discussed and a key figure of merit for dispersion compensating devices is defined. The design and optimization of dispersion compensating (DC) fiber is described with special attention to practical concerns including packaging and manufacturability. We describe experimental fabrication results of DC fiber, results of using the fiber to make compact dispersion compensating modules, and the outcome of recent systems experiments incorporating the fiber. >
TL;DR: In this paper, the authors used a calibrated, narrow-linewidth, single-frequency, continuously wavelength-tunable erbium fiber laser to the interrogation of a multipoint Bragg temperature sensor.
Abstract: This paper reports on the application of a calibrated, narrow-linewidth, single-frequency, continuously wavelength-tunable erbium fiber laser to the interrogation of a multipoint Bragg grating temperature sensor. The fiber laser was wavelength-tuned, through an array of three fiber Bragg grating sensors, to determine the temperature of each individual grating. The temperatures of the three gratings were measured as a function of grating Bragg wavelength. The minimum wavelength resolution, due to electro-mechanical repeatability, of the fiber laser source/analyzer was determined to be approximately 2.3 picometers. This corresponds to a frequency resolution of approximately 300 MHz. >