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Lightwave Technology, Journal of

Issue 8 • Date Aug 1989

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Displaying Results 1 - 21 of 21
  • High hydrostatic pressure effects in highly birefringent optical fibers

    Page(s): 1279 - 1283
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    The effect of high hydrostatic pressure on polarization properties in highly birefringent (HB) optical fibers is experimentally evaluated up to 200 MPa. The results are discussed in terms of beat-length changes under high pressure. It is found that oscillatory behavior of the output signal exiting from the HB bow-tie fiber and monitored in the plane parallel to one of its own two principal axes can be attributed to a pressure-induced increase of beat-length parameter. This effect can be applied to sense high hydrostatic pressure using appropriately configured HB fiber, but it could be a disadvantage in underwater communication systems using HB fibers if these are not adequately protected View full abstract»

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  • Improvements to the variable aperture method for measuring the mode-field diameter of dispersion-shifted fibers

    Page(s): 1158 - 1161
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    The variable aperture system for measuring single-mode fiber mode-field diameter is modified to provide accurate measurements of dispersion-shifted fibers. The system's numerical aperture (NA) is increased by using a spherical mirror and a large aperture wheel with 23 apertures out to 0.556 NA. Petermann's second mode-field diameter (MFD) definition is calculated with Simpson's rule numerical integration. The industrialized high-NA variable aperture method in the far field (VAMFF) system is accurate to within 1%, with a measurement standard deviation of less than 0.5%. Flexibility for measuring various fiber designs over a range of wavelengths is also a key feature. It is concluded that the industrialized high-NA VAMFF system is an excellent MFD measurement bench because of its precision, accuracy, and versatility View full abstract»

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  • Fiber-optic reflection measurements using OCWR and OTDR techniques

    Page(s): 1234 - 1241
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (532 KB)  

    A method for determining the backscatter and reflection responses of an optical fiber and reflector to an arbitrary input is developed. Two cases are specifically considered: a continuous-wave input and a rectangular pulse input. From the rectangular pulse input response, the equation is derived for computing the reflectance of a discrete component from an optical time-domain reflectometer (OTDR) measurement. Precautions are given for accurately performing reflectance measurements using an OTDR. Two methods are presented for determining the backscatter level of the fiber type under test, and its importance in reflection measurements is shown View full abstract»

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  • Dispersion measurement on fluoride glasses and fibers

    Page(s): 1256 - 1263
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    An overview is given of dispersion measurements on fluoride glasses and fibers, and the dispersion compensating capability of fluoride fibers is discussed. The temperature dependence of refractive-index dispersion and material dispersion of fluoride glasses is measured. These measurements indicate that fluoride glasses can compensate for temperature-dependent changes of refractive indices and material dispersion in silica glasses and fibers View full abstract»

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  • Real-time measurements of polarization fluctuations in an optical fiber submarine cable in a deep-sea trial using electrooptic LiNbO3 device

    Page(s): 1201 - 1206
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    An investigation of real-time polarization fluctuation measurements in an optical fiber submarine cable during laying and recovery in a 6000-m deep-sea trial is presented. State of polarization (SOP) variation measurements in real time are achieved by the Stokes parameter analyzer using an electrooptic LiNbO3 device. It is found that the SOP variations of the cable laying change randomly, while those of the cable recovery change uniformly. The maximum power spectra of the polarization fluctuations during cable installation are found experimentally to be less than about 50 Hz View full abstract»

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  • Novel chromatic dispersion measurement method over continuous Gigahertz tuning range

    Page(s): 1177 - 1180
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    A method for the measurement of chromatic dispersion in a single-mode optical fiber is proposed and demonstrated. This method adopts the technique of external modulation of the distributed feedback (DFB) laser output and direct optical frequency sweep range monitoring by coherent heterodyne detection. The method is also applicable to the future optical communication system with narrowband optical elements such as optical amplifiers, whereas measurement is impossible given the present state of the art View full abstract»

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  • Quadrature phase shift technique for measurement of strain, optical power transmission, and length in optical fibers

    Page(s): 1264 - 1269
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    A quadrature phase shift (QPS) technique is described that simultaneously measures the mechanical strain and optical power transmission on multimode and single-mode fibers. The principles of delay and power measurement are separately developed to derive the theoretical basis of the combined technique. The principles of the technique and its practical implementation are discussed. The technique is implemented using stabilized light-emitting diode sources which, unlike laser diodes, are insensitive to back reflections and allow any test wavelength in the usual wavebands to be chosen while being completely eye safe. Measurements on typical fiber and cable samples using a commercial QPS instrument are presented to demonstrate the versatility of the technique. The technique has applications such as cable tensile testing, temperature cycling, and installation monitoring. The technique is capable of state-of-the-art power/strain repeatability and long-term stability. Experimental results are given View full abstract»

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  • Refractive index profiling-state of the art

    Page(s): 1162 - 1169
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    Problems associated with different calibration techniques and some instrumental effects that can determine instrumental accuracy are discussed. It is shown how transmission effects can be observed and used to generate a correction curve for refracted near-field instruments. High-quality fiber slices needed for axial interferometry were used to obtain refractive index differences on suitable fibers to ±1% with the measurements traceable to national standards. Interferometry was used to calibrate a multiple-step fiber which is available in 10-m lengths with a certificate of calibration. The limitations of the technique are discussed, and preliminary results of a study on the effects of residual stress and stress relief on measurements are given. Comparisons are made between measurements made by axial interferometry and refracted near field on a range of fibers. It is shown that commercial profilers can produce reliable measurements of refractive index difference, absolute refractive index, profile shape, and numerical aperture that agree well with measurements by other techniques View full abstract»

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  • Submillimeter optical reflectometry

    Page(s): 1225 - 1233
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (784 KB)  

    The development of optical reflectometers with a spatial resolution in the submillimeter range is reviewed. Optical time-domain reflectometers (OTDRs) and optical low-coherence reflectometers (OLCRs) for nondestructive diagnostics of waveguide devices are discussed. Techniques, system performances, and experimental results are discussed for OTDRs and for OLCRs. Fields of applications for these techniques are indicated, and some preliminary conclusions are presented. A dynamic range of ~100 dB and a spatial resolution in the range of 10-60 μm were achieved with both types of reflectometers. Nondestructive diagnostics on waveguide components and integrated optics circuits are feasible at these performance levels View full abstract»

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  • BOTDA-nondestructive measurement of single-mode optical fiber attenuation characteristics using Brillouin interaction: theory

    Page(s): 1170 - 1176
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    A theoretical investigation of Brillouin optical-fiber time-domain analysis (BOTDA) is described. BOTDA uses Brillouin interaction in optical fibers to analyze the attenuation characteristics of the optical fibers nondestructively. The dynamic range performance of BOTDA is approximately 10-dB greater than that of conventional optical time-domain reflectometry View full abstract»

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  • Polarization measurements on single-mode fibers

    Page(s): 1187 - 1196
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1052 KB)  

    An overview of current measurement techniques on conventional and polarization maintaining single-mode fibers is presented. The various methods are discussed and classified with respect to the relevant polarization parameters. Applicability ranges and resolution are pointed out for different types of fibers View full abstract»

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  • Faraday rotation and its temperature dependence measurements in low-birefringence fibers

    Page(s): 1275 - 1278
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    A setup allowing a rapid and efficient determination of Faraday rotation in low-birefringence fibers in the absence of linear birefringence is presented. Practical results, i.e. the Verdet constant and its variation with temperature between 25°C and 140°C, are given for three specimens of commercial low-birefringence fiber at a wavelength of 633 nm and in a DC magnetic field. The measurement technique is shown to offer a rapid and efficient determination of the Verdet constant in the absence of linear birefringence View full abstract»

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  • A comparison of far-field methods for determining mode field diameter of single-mode fibers using both Gaussian and Petermann definitions

    Page(s): 1153 - 1157
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB)  

    An interlaboratory comparison is presented of far-field measurement methods for determining mode field diameter of single-mode fibers. The comparison was conducted by member of the Electronic Industries Association. Measurements were made on dispersion-unshifted and dispersion-shifted fibers at 1300 and 1550 nm. Results were calculated using both Petermann and Gaussian definitions. The Petermann definition gave better agreement than the Gaussian in all cases. A systematic offset of 0.52 μm was observed between methods when applied to dispersion-shifted fibers. Such an offset may be caused by limited angular collection View full abstract»

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  • Characterization of special fibers and fiber devices

    Page(s): 1242 - 1255
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    Methods for characterizing birefringent fibers (both those with high circular or linear birefringence and those with negligible intrinsic birefringence) are presented, and their relative merits are discussed. Fibers with high nonlinear coefficients exhibit interesting optical phenomena, and methods are developed to determine second harmonic, Pockels and Kerr effects, parametric phenomena, and the Verdet constant of silica and higher-loss, nonsilica fibers. Fibers containing rare-earth ions are of interest both as active (laser and amplifiers) and passive systems. Techniques are developed to characterize these devices, and conventional methods are modified to quantify dopant parameters within the fiber. Techniques for the measurement of the diverse properties of all these different fibers are presented with results, and, where appropriate, the problems with their characterization are discussed View full abstract»

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  • Polarization fluctuation measurements on installed single-mode optical fiber cables

    Page(s): 1197 - 1200
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB)  

    Measurements are reported of the polarization fluctuation observed at 1550 nm on samples of cable that Telecom Australia has installed in its interexchange network. The rate of polarization fluctuations is found to be slow, on the order of hours. The fluctuation in the polarization angle is typically in the range of 2-10° each day, with some changes up to about 25°. The results indicate there are no significant limitations on implementing polarization control in a coherent system receiver View full abstract»

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  • Mode coupling effects of the cutoff wavelength characteristics of dispersion-shifted and dispersion-unshifted single-mode fibers

    Page(s): 1181 - 1186
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (516 KB)  

    The authors present theoretical background and experimental results to clarify the nature of the hump in the cutoff region of different types of single-mode fibers and discuss its implications. A theoretical model in terms of the coupling between the whispering-gallery mode formed near the silica-cladding/primary-coating boundary and the first higher-order core mode is presented to explain the presence of the hump. An experimental verification of this theoretical model is presented for these fibers. In addition, the curvature sensitivity of the hump is studied for these three fiber types. The results of the study show that for both dispersion-shifted and matched-cladding, dispersion-unshifted fibers, the hump is curvature sensitive and occurs at intermediate (28 and 15 cm) bend diameters. At large (40 cm) and small (10 cm) bend diameters, the hump was not observed in the cutoff region of these two fiber types. However, in the case of the depressed-cladding fiber, the hump was found to be curvature insensitive and occurred at all bend diameters (40, 28, 15, and 10 cm) used in this study View full abstract»

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  • Stress measurements of fibers and preforms

    Page(s): 1270 - 1274
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    The authors point out the formation mechanism of axial stress, describes the method and the apparatus used for measurements, and presents the results obtained during a study of loss reduction on trapezoidal core 1.55-μm dispersion-shifted fibers manufactured by the MCVD technique. It is concluded that the stress measurements on fiber are less accurate than those on preform (experimental dispersion reaches 15% instead of 5%). The various observations made from measurements on preform show that the axial stress is related to the index profile and that the core axial stress increases with the GeO2 content. The measurements performed on fiber show that the level of stress is linearly dependent on the drawing tension and that the stress profile is related to the glass-transition temperature of the different materials. Furthermore, this method of stress measurement is complementary to the more standard index profile measurement on fiber or on preform View full abstract»

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  • Mode field diameter measurements in single-mode optical fibers

    Page(s): 1139 - 1152
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    The role of the mode field diameter in the characterization of single-mode fibers is examined. The most relevant definitions of this parameter are reviewed, and a comparative analysis of methods for its measurement is performed. All the discussed measurement methods have reached a repeatability and reproducibility which are quite satisfying. Emphasis is given to the requirements posed by the new fiber designs, such as the polarization-maintaining structures. Most of the discussed techniques have been industrialized, and a number of instruments based on them are commercially available; however, it is predicted that the evolution of fiber design will impose new requirements on some of these instruments View full abstract»

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  • Advances in optical time domain reflectometry

    Page(s): 1217 - 1224
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (668 KB)  

    Advances in optical time-domain reflectometry (OTDR), such as enlargement of dynamic range, enhancement in resolution, reduction of noise intrinsic to single-mode fibers, and increase in user friendliness of the equipment, are reviewed. The gated detection technique and recent progress in OTDR are presented. Future optical network diagnostics are discussed View full abstract»

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  • High-resolution measurement of birefringence profiles in stress-induced polarization-maintaining fibers

    Page(s): 1213 - 1216
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    A novel technique for measuring the local refractive-index anisotropy in stress-induced polarization-maintaining fibers is presented. This technique is an extension of the well-known refracted near-field method for high-resolution measurement of refractive-index profiles. The application of this technique to two different types of fiber reveals birefringence profiles as well as differential stress profiles. Calculated birefringent profiles determined by means of a finite-element method are in good agreement with measured ones. Interferometrically measured modal birefringence verified corresponding data obtained from birefringence profiles View full abstract»

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  • Birefringence measurements in fibers without polarizer

    Page(s): 1207 - 1212
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    A method for measuring the delay between polarization eigenmodes in either high- or low-birefringence fibers is described. The main advantage of this interferometric method is its ability to perform the measurements without the use of any polarizing device. This results in particularly easy handling and makes this technique very suitable for systematic fiber controls. The obtained accuracy using an all-fiber setup is 0.02 ps/m for highly birefringent fibers and 0.003 ps/m when the birefringence is low 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.

Full Aims & Scope

Meet Our Editors

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