Showing papers on "Dispersion-shifted fiber published in 1978"
TL;DR: In this article, the polarization and magnetooptic properties of a sample of singlemode optical fiber have been investigated and the fiber acts as a linear retarder, and the degree of retardation is dependent on the external pressure applied to the fiber.
Abstract: The polarization and magnetooptic properties of a sample of single-mode optical fiber have been investigated. The fiber acts as a linear retarder, and the degree of retardation is dependent on the external pressure applied to the fiber. The stress optic coefficient is found to be 8.72 x 10(-10) N(-1) m(2). The direction of linear polarization is rotated when a longitudinal magnetic field is applied to the fiber (Faraday effect). The Verdet constant is 1.56 x 10(-2) min A(-1). The intrinsic specific linear retardation of the fiber is found to be less than 0.44 rad m(-1) from the magnetooptic measurements. The fiber has been used in an experimental current measurement device.
284 citations
TL;DR: In this paper, material dispersion measurements on six characteristic lightguide glass compositions are reported on bulk specimens and cover the wavelength range from 0.8 to 1.5 μm.
Abstract: Material dispersion measurements are reported on six characteristic lightguide glass compositions. The measurements were made on bulk specimens and cover the wavelength range from 0.8 to 1.5 μm. It is observed that in these silicate glasses the wavelength at which material dispersion is zero is in all cases greater than 1.2μm.
236 citations
TL;DR: The resulting mode dispersion in short fiber lengths from the depolarization of broad-bandwidth light is measured, in good agreement with the observed birefringence.
Abstract: In real single-mode optical fibers, imperfections cause the two possible polarizations to propagate at different phase velocities This birefringence leads to different group velocities We have measured the resulting mode dispersion in short fiber lengths (05-25 m) from the depolarization of broad-bandwidth light In a typical fiber we found 30 psec/km at 069-microm wavelength, in good agreement with the observed birefringence The effect of mode dispersion can be compensated by a +/-68 degrees double twist midway along the fiber, interchanging the fast and slow modes
182 citations
TL;DR: In this paper, a new type of fiber optical waveguide utilizing TlBr and KRS•5 has been prepared; its infrared transparency extends to wavelengths well beyond those transmitted by known glassy materials.
Abstract: A new type of fiber optical waveguide utilizing TlBr and KRS‐5 has been prepared; its infrared transparency extends to wavelengths well beyond those transmitted by known glassy materials.
164 citations
TL;DR: In this paper, a universal fiber-optic measurement system for measuring loss and dispersion in the 1.06-1.6 \mu m wavelength region is described, where the source is a silica fiber Raman laser pumped by a mode-locked and Q-switched Nd:YAG laser.
Abstract: A universal fiber-optic measurement system, which is useful for measuring loss and dispersion in the 1.06-1.6 \mu m wavelength region, is described. The source is a silica fiber Raman laser pumped by a mode-locked and Q -switched Nd:YAG laser at 1.06 μm. Subnanosecond multiple-Stokes pulses in the 1.1-1.6 \mu m wavelength region are generated in a low-loss single-mode silica fiber. The use of this near-infrared fiber Raman laser for characterizing various transmission properties of single and multimode test fibers is demonstrated. Loss spectra, intramodal dispersion, and intermodal dispersion data are obtained in the wavelength region of minimum loss and minimum material dispersion for silica fibers.
148 citations
TL;DR: Through this study, it has become clear that WDM technologies play a major role in optical fiber systems and have the possibilities of realizing the various optical fiber transmission systems.
Abstract: This paper describes the feasibility and the applicability of the Wavelength-Division-Multiplexing (WDM) system with two types of preliminary WDM transmission experiments. Through this study, it has become clear that WDM technologies play a major role in optical fiber systems and have the possibilities of realizing the various optical fiber transmission systems.
90 citations
28 Jun 1978
TL;DR: In this article, an optical fiber acoustical sensor for detecting sound waves in a fluid mum is presented, where a sound wave propagating through the fluid medium and incident on the optical fiber coil changes the index of refraction and the length of the optical fibre at the area of incidence.
Abstract: An optical fiber acoustical sensor for detecting sound waves in a fluid mum. An optical fiber coil through which a light beam is transmitted is placed in a fluid medium. A sound wave propagating through the fluid medium and incident on the optical fiber coil changes the index of refraction and the length of the optical fiber at the area of incidence. These changes cause a shift in the transmitted light which is detectable to denote the presence of the sound wave.
85 citations
TL;DR: In this paper, a method for direct and precise measurement of wavelength dispersion in the core of an optical fiber over a wide wavelength region is described, and a new method is described for direct measurement of the dispersion.
Abstract: A new method is described for direct and precise measurement of wavelength dispersion in the core of an optical fibre over a wide wavelength region.
41 citations
01 Apr 1978
TL;DR: Measurements currently employed to determine the characteristics of optical fiber waveguides are reviewed and a brief review of the dominant causes of attenuation and modal delay in fibers is also included.
Abstract: Recent advances in optical-fiber technology dictate that attention must be given to establishing accurate and precise measurement techniques. In this paper measurements currently employed to determine the characteristics of optical fiber waveguides are reviewed. Included in the review are techniques for measuring attenuation, delay distortion, refractive-index profile, fiber diameter, and mechanical strength. Since establishment of accurate measurement procedures cannot be accomplished without some knowledge of the physical mechanisms controlling the parameters to be measured, a brief review of the dominant causes of attenuation and modal delay in fibers is also included.
39 citations
TL;DR: In this article, the authors investigated the output coupling of light from a conically tapered optical fiber and showed that light which is coupled out of a taper is widely dispersed when the taper angle is large.
Abstract: Output coupling of light from a conically tapered optical fiber is investigated. Such a technique may be used to provide “wide-angle” illumination from a single fiber of low numerical aperture. Experimental results for a series of fibers of varying taper angles are presented. It is found experimentally that light which is coupled out of a taper is widely dispersed when the taper angle is large. Based upon modified geometrical optics we present a theory which qualitatively predicts the experimentally measured radiation intensity patterns.
TL;DR: In this paper, an optical fiber acoustical sensor for sensing acoustic vibrations and in combination with an incoherent or coherent source of light such as a LED or a laser and a photo detector to determine the frequency and amplitude of sound pressure variations.
Abstract: This invention relates to an optical fiber acoustical sensor for sensing acoustic vibrations and in combination with an incoherent or coherent source of light such as a LED or a laser and a photo detector to determine the frequency and amplitude of the sound pressure variations. The invention consists of an element of optical fiber without cladding surrounded by a liquid or plastic potting material permeable to sound pressure and having an index of refraction slightly less than the fiber. The intensity of a light beam transmitted by means of fiber optic waveguides, single or multi-mode, from a source of light through the sensor to a photo detector varies with the variation of sound pressure to which the sensor is subjected. If the sensor is in water, the transmitted light intensity varies with the acoustical pressure in the water because the changes in liquid or plastic index of refraction changes with the sound pressure. Generally the fiber sensor is in an element preferably surrounded by a fluid which has an index of refraction close to but less than that of the fiber, and the coil thickness is small relative to the wavelength of the sound to be detected.
TL;DR: A single-mode fiber coupler to the Ti diffused LiNbO(3) strip waveguide has been devised that has a special feature wherein coupling degradation caused by fiber displacement after connection can be recovered to the initial state.
Abstract: A single-mode fiber coupler to the Ti diffused LiNbO3 strip waveguide has been devised. The influences of three axial displacements and two angular misalignments on the coupling efficiency have been investigated at 6328-A wavelength. The coupler has a special feature wherein coupling degradation caused by fiber displacement after connection can be recovered to the initial state. The total optical insertion loss is 3 dB after fixing the fiber to the LiNbO3 strip waveguide, which is 4 μm wide and 8 mm long.
TL;DR: In this paper, the modal dispersion in the optical fiber with truncated parabolic index distribution is analyzed theoretically in detail by using a variational method, taking the influence of the cladding upon the propagating modes into consideration.
Abstract: The use of a parabolic-index fiber as an optical transmission line has been receiving extensive attention because of its excellent mode dispersion characteristics. In the present paper, the modal dispersion in the optical fiber with truncated parabolic index distribution is analyzed theoretically in detail by using a variational method. Taking the influence of the cladding upon the propagating modes into consideration, it is found that there exists an optimum index distribution for which the modal dispersion is minimized. The standard deviation of the normalized group delay of propagating modes is used to estimate the modal dispersion behavior of the fiber.
TL;DR: It is shown that control of the layer width is an effective means for achieving the desired loss and bandwidth and the wavelength dependence of microbending loss of a W-type fiber is described.
Abstract: The transmission mechanism of a multimode W-type optical fiber is clarified by the experimental study of the effect of the intermediate layer on the transmission characteristics. It is shown that control of the layer width is an effective means for achieving the desired loss and bandwidth. A W-type fiber with a thick intermediate layer has a transmission loss on the order of 2 dB/km. To determine the transmission characteristics of a W-type fiber applicable to system design, the length dependence of several fiber characteristics is investigated. Concepts such as splices used as mode scramblers and the effect of the intermediate layer as a barrier against OH absorption loss are introduced. The wavelength dependence of microbending loss of a W-type fiber is also described.
TL;DR: A method is presented for calculating offset and tilt losses for fiber splices with axially symmetric arbitrary-index profiles by approximating the profile with a staircase function and the dual-mode fiber is superior to the step- and parabolic-index fibers with respect to permissible splice offset tolerances.
Abstract: A method is presented for calculating offset and tilt losses for fiber splices with axially symmetric arbitrary-index profiles by approximating the profile with a staircase function. This method is applied to a large-core dual-mode fiber with zero intermodal dispersion as well as to single-mode fibers with step- and parabolic-index profiles. When a splice loss of 0.2 dB is permitted, the normalized offset misalignment is found to be D(N) = 0.635 for the dual-mode fiber at normalized frequency v = 4.605 and a power-law exponent alpha = 4.5. The D(N) value compares favorably with the values 0.560 and 0.614 for conventional step- and parabolic-index single-mode fibers, respectively. The dual-mode fiber is superior to the step- and parabolic-index fibers with respect to permissible splice offset tolerances.
TL;DR: This Letter presents an optical fiber switch driven by PZT bimorph as one attempt at switching speed improvement, which reduces chattering by applying a multistep voltage.
Abstract: Optical fiber communications need optical switches. For a multimode fiber system, an optical fiber switch is suitable for a low switching loss. At present, an optical fiber switch has low switching speed. Short switching time in a system results in increased traffic handling capacity. In this Letter, an optical fiber switch driven by PZT bimorph is presented as one attempt at switching speed improvement. Chattering, which is one cause of low switching speed, is reduced by applying a multistep voltage. The 1 × 2 optical switch consisted of one movable optical fiber and two fixed optical fibers, as shown in Fig. 1. The movable optical fiber was driven by a PZT ceramics bimorph. The optical fiber used in this experiment was a multimode fiber of the step-index type with a 60-μm core diam and 150-μm outer diam. The bimorph was constructed with two Fig. 1. Optical fiber switch description.
TL;DR: An 800-Mbit/sec optical fiber transmission experiment at the 1.05-microm wavelength is reported and it is shown that, since the repeater spacing is limited by loss rather than dispersion in the present system configuration, a more than 10-km repeater spaced seems to be feasible.
Abstract: An 800-Mbit/sec optical fiber transmission experiment at the 1.05-μm wavelength is reported. Single frequency output of a LiNdP4O12 laser is modulated with a guided-wave LiNbO3 modulator in an NRZ code and is transmitted through 4-km long single-mode fibers. The minimum receiving level is −30 dBm using a Ge avalanche photodiode. It is shown that, since the repeater spacing is limited by loss rather than dispersion in the present system configuration, a more than 10-km repeater spacing seems to be feasible. Distinctive features and problems associated with the system and constituent devices are discussed.
TL;DR: The effect of different launching conditions on the loss measured with a calorimeter in short (~1-m) lengths of multimode optical fiber is described and many examples are presented that illustrate the effect that launch conditions have on the fiber loss.
Abstract: In this paper we describe the effect of different launching conditions on the loss measured with a calorimeter in short (~1-m) lengths of multimode optical fiber. A qualitative description of the relation between the energy distribution in the fiber and various excitation variables is given, and many examples are presented that illustrate the effect that launch conditions have on the fiber loss. The use of launch-dependent loss phenomena to diagnose loss mechanisms in optical fibers is discussed. In particular, loss plots are shown for two germania-doped silica-core fibers that indicate a strong absorption loss mechanism located deep within the fiber core.
Patent•
22 Nov 1978TL;DR: An optical waveguide coupler having intersecting deep and shallow grooves in a planar solid substrate, in which the deep groove accommodates an alignment fiber for fine vertical alignment of an optical fiber with another optical fiber or with an optical component such as a switch, modulator, multiplexer or source of light as discussed by the authors.
Abstract: An optical waveguide coupler having intersecting deep and shallow grooves in a planar solid substrate, in which the deep groove accommodates an alignment fiber for fine vertical alignment of an optical fiber with another optical fiber or with an optical component such as a switch, modulator, multiplexer or source of light. The shallow groove accommodates the optical fiber. The alignment fiber may be tapered or have any configuration such that its manipulation causes the alignment fiber to contact the underside of the optical fiber for raising or lowering the optical fiber. There may be a plurality of shallow and deep grooves for coupling more than one optical fiber.
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TL;DR: A device which samples the optical signal in an optical fiber for use in source stabilization via feedback control incorporates a beam splitter formed on the fiber ends to deflect a portion of the light traveling down the fiber into a P-I-N photodetector.
Abstract: This paper describes a device which samples the optical signal in an optical fiber for use in source stabilization via feedback control. This device incorporates a beam splitter formed on the fiber ends to deflect a portion of the light traveling down the fiber into a P-I-N photodetector. Advantages of this device include low insertion loss, an output that is relatively independent of the modal distribution within the fiber, and is a rugged small package.
Patent•
19 Apr 1978TL;DR: An injection laser diode is at one end of an optical fiber to direct modulated optical radiation into the fiber at the other end of the fiber is a detector, such as a semiconductor photodetector, for the modulated radiation as mentioned in this paper.
Abstract: An injection laser diode is at one end of an optical fiber to direct modulated optical radiation into the fiber. At the other end of the fiber is a detector, such as a semiconductor photodetector, for the modulated radiation. Between the other end of the optical fiber and the detector is a reflecting shutter which is adapted to periodically reflect some of the radiation, at a lower frequency rate, back along the optical fiber to the injection laser. The radiation reflected back into the injection laser causes a variation in the characteristics of the laser so that the laser operates as a detector for the reflected radiation.
Patent•
12 Oct 1978
TL;DR: In this article, the authors proposed to improve the optical coupling efficiency by making an optical fiber having a smaller core diameter so taper as to have a larger numerical aperture and giving a special condition to the taper angle when the optical fiber is coupled to an optical fibre having a larger core diameter.
Abstract: PURPOSE:To improve the optical coupling efficiency by making an optical fiber having a smaller core diameter so taper as to have a larger numerical aperture and by giving a special condition to the taper angle when the optical fiber is coupled to an optical fiber having a larger core diameter.
Patent•
12 Apr 1978TL;DR: In this paper, an optical fiber is drawn from an appropriate preform using a laser whose output power is varied periodically at a rate greater than ten times a second, which enhances the mode conversion properties of the fiber and reduces the pulse dispersion.
Abstract: An optical fiber is drawn from an appropriate preform using a laser whose output power is varied periodically at a rate greater than ten times a second. A fiber drawn in this manner has periodic variations in diameter which enhance the mode conversion properties of the fiber and thereby reduce the pulse dispersion of a signal transmitted through the waveguide.
TL;DR: In this paper, a method based on the selective mode excitation at different wavelengths for studying the profile dispersion influence on the modal dispersion was described, which is able to determine either the optimum wavelength at which the fiber should be operated or the correction needed for optimising the index profile at a given wavelength.
Abstract: We describe a method based on the selective mode excitation at different wavelengths for studying the profile dispersion influence on the modal dispersion. By using this technique, we are able to determine either the optimum wavelength at which the fibre should be operated or the correction needed for optimising the index profile at a given wavelength.
TL;DR: In this paper, an electrooptic system has been developed to produce and detect the interference fringe pattern in which the fringe spacing is inversely proportional to the fiber diameter, thus providing a measure of fiber diameter.
Abstract: Forward scattering of light by an optical fiber produces an interference fringe pattern in which the fringe spacing is inversely proportional to the fiber diameter. An electrooptic system has been developed to produce and detect this scattering pattern, thus providing a measure of fiber diameter.
01 Jan 1978
TL;DR: In this paper, a technique based on the preservation of the axial angle for transmitting one-dimensional light distribution through a single multimode step-index optical fiber is described, and an extension to transmission of two-dimensional pictures is demonstrated.
Abstract: A technique, based on the preservation of the axial angle, for transmitting one‐dimensional light distribution through a single multimode step‐index optical fiber is described. Extension to transmission of two‐dimensional pictures is demonstrated.
Patent•
23 Aug 1978TL;DR: An interferometer gyro employing a coiled optical fiber includes a pair of acousto-optic modulators to modulate first and second frequencies onto two components divided from the light of a light source as discussed by the authors.
Abstract: An interferometer gyro employing a coiled optical fiber includes a pair of acousto-optic modulators to modulate first and second frequencies onto two components divided from the light of a light source. The light source need not exhibit the high degree of source coherence heretofore required, and can be an incandescent bulb in many applications. The first and second modulated light components are injected in opposite or counter-rotating directions into the optical fiber wherein they experience phase changes due to the apparent change in optical length of the optical fiber upon rotation of the fiber about an axis of sensitivity. The light components are then, after being removed from the fiber, combined and compared with the signals applied at the input. The phase difference therebetween is then established to measure the rate of rotation of the optical fiber about the axis of sensitivity.
TL;DR: An efficient method is presented which helps to explain the interaction of both effects, shows a new way of minimizing the total dispersion by matching the two effects, and simplifies the calculation of pulse broadening in imperfect real fibers.
Abstract: Group delay differences among modes, which limit the bandwidth of optical fibers, arise not only from distortions of the refractive profile but also from profile dispersion caused by the dependence of the profile contour on wavelength. An efficient method is presented which helps to explain the interaction of both effects, shows a new way of minimizing the total dispersion by matching the two effects, and simplifies the calculation of pulse broadening in imperfect real fibers.