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Showing papers on "Dispersion-shifted fiber published in 1986"


Journal ArticleDOI
TL;DR: In this article, the theoretical and practical attempts to develop advanced fiber designs have been reviewed, and a detailed review of the existing fiber structures can be found in Section 2.1.
Abstract: Standard first-generation single-mode fibers are optimized for operation at a wavelength of 1.3 μm, where they exhibit zero dispersion. By modifying the fiber design it is possible to shift the zero dispersion wavelength to 1.55 μm, where the lowest losses occur in silica-based fibers. Advanced fiber structures can also be designed such that relatively flat dispersion spectra can be achieved over a wide range of wavelengths. In this paper, the theoretical and practical attempts to develop advanced fiber designs have been reviewed.

183 citations


Journal ArticleDOI
TL;DR: The propagation of optical pulses is considered at the zero-dispersion wavelength of nonlinear dispersive fibers of single-mode silica fibers and the evolution of pulse shapes and pulse spectra along the fiber length for a wide range of initial pulse widths is studied.
Abstract: The propagation of optical pulses is considered at the zero-dispersion wavelength of nonlinear dispersive fibers. Even in the absence of group-velocity (first-order) dispersion, higher-order dispersive effects in single-mode silica fibers are found to be strong enough to cause significant broadening and distortion of picosecond optical pulses for fiber lengths of 10\char21{}100 km. Using the parameters appropriate for a 1.55-\ensuremath{\mu}m dispersion-shifted single-mode fiber, we have studied the evolution of pulse shapes and pulse spectra along the fiber length for a wide range of initial pulse widths. For peak powers \ensuremath{\sim}10 mW, the dispersive and nonlinear effects are comparable for pulse widths \ensuremath{\sim}1 ps and their mutual interplay leads to new qualitative features in the pulse shape and spectrum that are largely independent of the input profile. The theoretical results are useful for an understanding of the higher-order dispersion and, at the same time, have implications for high-capacity, long-haul, optical communication systems.

123 citations


Patent
23 Jun 1986
TL;DR: In this article, the optical fiber is wrapped around the base member, and one part of the outer circumferential area of the wrapped fiber is processed in order to form a flat surface, and the excitation light is introduced to another surface of the prism.
Abstract: To provide a low-cost, high reliability and high-powered operation enabled optical fiber laser, in the optical fiber laser for oscillating a laser light by introducing an excitation light for exciting the rare earth elements into the optical fiber doped partially by the rare earth elements, the optical fiber is wrapped around the base member, and one part of the outer circumferential area of the wrapped optical fiber is processed in order to form a flat surface, and one face of the prism is made contacted to the flat surface, and the excitation light is introduced to another surface of the prism

108 citations


Journal ArticleDOI
TL;DR: In this paper, the authors presented transmission characteristics and reliability for pure-silica-core singlemode fiber with matched cladding, and achieved minimum attenuation was 0.154 dB/km at 1.56 µm, which is the lowest attenuation ever reported.
Abstract: Transmission characteristics and reliability for pure-silica-core single-mode fiber with matched cladding are presented. On account of the "pure" silica core, without any additives, the fiber features the low attenuation and improved chemical stability under the existence of hydrogen and γ-ray radiation. High mechanical reliability and good splicing behavior of the fibers were also confirmed. More than 2000 km of pure-silica-core fiber have been fabricated, exhibiting median attenuation of 0.35 dB/km at 1.3 μm and 0.21 dB/ km at 1.55 μm. The achieved minimum attenuation was 0.154 dB/km at 1.55-1.56 \mu m, which is the lowest attenuation ever reported.

90 citations


Journal ArticleDOI
TL;DR: In this paper, the dependence of pulsewidth on the electrical drive waveform and the repetition rate is investigated, and limitations on the pulsewidth are discussed, and a composite-cavity structure with an efficient single-mode fiber output port is discussed.
Abstract: Composite-cavity semiconductor lasers using integral single-mode fiber resonators are capable of producing short-duration mode-locked optical pulses at very high repetition rates. This paper summarizes recent experiments using a composite-cavity structure with an efficient single-mode fiber output port. The dependence of pulse-width on the electrical drive waveform and the repetition rate is investigated, and limitations on the pulsewidth are discussed.

75 citations


Journal ArticleDOI
TL;DR: In this paper, the fiber technique has been applied to X-rays by the use of a thin capillary of glass and the critical angles for total reflection have been measured and compared with calculated values from a simple theory.
Abstract: The fiber technique has been applied to X-rays by the use of a thin capillary of glass. The critical angles for total reflection have been measured and compared with calculated values from a simple theory. The ability of bending the X-ray beam within the fiber has been demonstrated.

59 citations


PatentDOI
09 Jun 1986
TL;DR: In this article, a dispersion compensation delay line is added to a synchronously pumped fiber Raman ring oscillator to generate sub-picosecond pulses, and an interference filter is used as a bandwidth limiting tuning element to provide a good quality short pulse.
Abstract: A dispersion compensation delay line is added to a synchronously pumped fiber Raman ring oscillator to generate subpicosecond pulses. A pair of spaced gratings form the delay line. An interference filter is used as a bandwidth limiting tuning element to provide a good quality short pulse. An integrated design eliminates the discrete optical elements by using only an optical fiber and an optical fiber coupler.

52 citations


Journal ArticleDOI
TL;DR: The design of an optical frequency-divisionmultiplexing distribution system is described and investigation is made of periodic filters for frequency division multiplexers and FS-SW, and the optical source, as well as single-mode fiber polarization mode dispersion.
Abstract: Optical frequency-division-multiplexing distribution systems providing more than ten frequency multiplexed optical signals separated by on the order of gigahertz, distribute signals to plural receivers, where one of the signals is selected by a frequency selection switch (FS-SW). This paper describes the design of an optical frequency-divisionmultiplexing distribution system. Investigation is made of periodic filters for frequency division multiplexers and FS-SW, and the optical source, as well as single-mode fiber polarization mode dispersion. Preliminary transmission experiments using a bit rate of 450 Mbits/s, fiber length of 13 km, and frequency spacing of 11 GHz are also demonstrated at a 1.5 μm wavelength to show the design's suitability.

50 citations


Journal ArticleDOI
TL;DR: In this article, phase error bounds for a fiber gyro with an imperfect polarizer are calculated assuming a broad-band source and high-birefringence fiber, and the phase error and resulting zero-point drift is related to the polarization-holding parameter h of the fiber.
Abstract: Phase error bounds for a fiber gyro with an imperfect polarizer are calculated assuming a broad-band source and high-birefringence fiber. The phase error and resulting zero-point drift is related to the polarization-holding parameter h of the fiber. Comparison of the theory with recent experimentally observed bias drift is made.

35 citations


Journal ArticleDOI
TL;DR: A prototype device has a passband 5 nm wide with a peak optical wavelength that can be tuned from 570 to 630 nm by changing the acoustic frequency from 2.85 to 2.55 MHz.
Abstract: Light can be coupled between the two principal polarizations of birefringent fiber by using a traveling acoustic wave to produce a spatially periodic stress in the fiber. For a fixed acoustic frequency, maximum coupling occurs when the input optical wavelength is such that the beat length of the fiber equals the acoustic wavelength. By changing the acoustic frequency, the wavelength at which peak coupling occurs can be tuned. A prototype device has a passband 5 nm wide with a peak optical wavelength that can be tuned from 570 to 630 nm by changing the acoustic frequency from 2.85 to 2.55 MHz.

31 citations


Journal ArticleDOI
TL;DR: In this paper, the first semiconductor-optical fiber ring laser is presented, which uses an InGaAsP traveling wave optical amplifier as the gain medium and a 1m length of highly birefringent fiber as the feedback loop.
Abstract: We demonstrate the first semiconductor‐optical fiber ring laser. The laser uses an InGaAsP traveling wave optical amplifier as the gain medium and a 1‐m length of highly birefringent fiber as the feedback loop. Output coupling is provided by a fiber directional coupler. The highly birefringent fiber is used as an intracavity wavelength filter, enabling single‐frequency oscillation with a narrow linewidth at a wavelength near 1.55 μm.

Patent
10 Apr 1986
TL;DR: In this paper, the relationship between the light transmission loss L 500 (dB/km) of a polycarbonate fiber as measured at a wavelength of 500 nm and that measured at 660 nm was expressed by the following inequality: L.500
Abstract: A plastic optical fiber which is superior in the light transmission characteristics, particularly in those within a visible light region and also superior in heat resistance, and a process for producing the same are provided, which plastic optical fiber comprises a polycarbonate as its core material and a polymer as its cladding material having a refractive index lower than that of the core material, wherein the relationship between the light transmission loss L 500 (dB/km) of the fiber as measured at a wavelength of 500 nm and that as measured at 660 nm being expressed by the following inequality: L.sub.500

Journal ArticleDOI
TL;DR: A new plastic optical fiber star coupler and the means of fabricating it have been developed and low-cost optical star couplers with large port number, low excess loss, and small power deviation can be obtained.
Abstract: A new plastic optical fiber star coupler and the means of fabricating it have been developed. This coupler has been realized by twisting and pulling the waist region of a biconical tapered fiber bundle made by pretapered fibers while heating. Controlling the biconical tapered shape has been achieved by jetting gas on the fiber surface while heating the fiber bundle. By using this fabrication method, the desired diameter mixing portion can be formed without breakage from melting. Low-cost optical star couplers with large port number, low excess loss, and small power deviation can be obtained.

Patent
09 Jul 1986
TL;DR: In this paper, a modal coupler for coupling between first and second order modes of an optical fiber, comprises a single continuous strand of optical fiber and a device for applying stress to the optical fiber at spaced intervals along the fiber.
Abstract: A modal coupler, for coupling between first and second order modes of an optical fiber, comprises a single continuous strand of optical fiber, and a device for applying stress to the optical fiber at spaced intervals along the fiber. The stress deforms the fiber and abruptly changes the fiber geometry at the beginning and end of each stressed region. The change in fiber geometry causes coupling of light from the fundamental mode to the second order mode. The coupler, under certain conditions, exhibits polarization dependence, and thus, it may be utilized as a fiber optic polarizer. In addition, the device couples coherently, and may be used in interferometric systems.

Patent
21 Feb 1986
TL;DR: In this article, an optical time-domain reflectometer (OTDR) using heterodyne reception for determining the attenuation of an optical fiber guide by measuring the backscattered portion of light pulses launched into the fiber.
Abstract: The invention relates to an optical time-domain reflectometer (OTDR) using heterodyne reception for determining the attenuation of an optical fiber guide by measuring the backscattered portion of light pulses launched into the fiber. The reflectometer comprises a light source whose light is split into a local-oscillator beam and a measuring beam. The measuring beam is pulsed by an acousto-optical modulator (AOM) and is then launched into the optical fiber to be tested. The measuring beam thus has a frequency which is offset from the optical frequency by an acoustic frequency. The local-oscillator beam and the back-scattered portion of the measuring beam are both directed to an optical receiver producing an electric output signal. A component of the output signal has a frequency corresponding to the acoustic frequency. The time-dependent amplitude of this component is a measure of the length-dependent attenuation of the optical fiber. In order to reduce the losses in the path between the light source and the optical receiver via the fiber to be tested, the acousto-optical modulator (AOM) also functions as an optical deflection element.

Journal ArticleDOI
TL;DR: In this paper, a 50-fold fiber-grating pulse compression in the near-infrared region was reported using a mode-locked neodymium:yttrium aluminum garnet laser operated at 1.319 μm.
Abstract: We report a 50‐fold fiber‐grating pulse compression in the near‐infrared region. 100 ps (FWHM) pulses from a mode‐locked neodymium:yttrium aluminum garnet laser operated at 1.319 μm have been compressed into 2 ps pulses by using a 2‐km dispersion‐shifted fiber and a grating pair separated by 2.41 m in a double‐pass configuration. The novel feature of this demonstration is the use of dispersion‐shifted fiber (zero‐dispersion wavelength at 1.59 μm) for producing a linear chirp over most of the pulse and, thus, almost all the input power appears in the compressed pulse.

Patent
20 Feb 1986
TL;DR: In this paper, the induced modulational instability in a single-mode optical fiber has been used to generate high repetition rates with anomalous dispersion at f 1 and f 2 by coupling first and second cw or quasi cw optical radiation.
Abstract: Optical pulses of nominal frequency f o and of predetermined repetition rate τ M -1 can be generated by means of the induced modulational instability in single mode optical fiber, provided the fiber has anomalous dispersion at f o . A particularly advantageous method for generating such pulses that is capable of very high repetition rates is disclosed. The method involves coupling first and second cw or quasi cw optical radiation, of frequencies f 1 and f 2 , respectively, into the optical fiber. Frequently one of the two radiations has much greater amplitude than the other. The resultant radiation in the fiber has frequency f o between f 1 and f 2 , and is sinusoidally modulated with frequency |f 1 -f 2 |. Propagation of the resultant radiation through the fiber results in steepening and narrowing of the amplitude peaks. The length of the fiber typically is chosen such that, at the output, the pulse width τ p <τ M /4, preferably <τ M /10. The inventive pulse generation method can advantageously be used in optical communications systems, e.g., in soliton systems. Other uses, e.g., in information processing apparatus, are also contemplated.

Patent
19 Dec 1986
TL;DR: In this paper, an apparatus and method for measuring dispersion in an optical fiber including transmitting light of a first wavelength and a second wavelength through the optical fiber, measuring the difference in time required for light of the first and second wavelengths to traverse the fiber, and calculating the dispersion of the fiber from the two wavelengths and the time difference.
Abstract: An apparatus and method for measuring dispersion in an optical fiber including transmitting light of a first wavelength and a second wavelength through the optical fiber, measuring the difference in time required for light of the first wavelength and light of the second wavelength to traverse the fiber, and calculating the dispersion of the fiber from the two wavelengths and the time difference. Lasers may be used as light sources and an oscilloscope may be used to measure the time difference.

Journal ArticleDOI
TL;DR: Two-amplitude modulators have been constructed and studied operating at 633 and 830 nm, and a modulation depth of 97% has been observed at 23.4 kHz for an excess loss of ~6 dB.
Abstract: Single-mode fiber used at a wavelength below its cutoff wavelength guides second-order modes which travel at different phase velocities than the fundamental modes. Such two-transverse-mode fiber forms a single-strand interferometer, and studies have shown that the output may be set at quadrature by using all-fiber polarization controllers. Furthermore, modulation of the two-mode fiber with a piezoelectric stretcher produces amplitude modulation. Two-amplitude modulators have been constructed and studied operating at 633 and 830 nm, and a modulation depth of 97% has been observed at 23.4 kHz for an excess loss of ~6 dB.

Patent
08 Aug 1986
TL;DR: In this article, the dispersion transformer is used for receiving light from one of the components and dispersing/separating the light into the plurality of spatially separated beams which are directed onto the endface of a multimode optical fiber.
Abstract: An optical transmission system wherein light is transmitted from a transmitter to a receiver by at least one transmission optical fiber. The system includes a dispersion transformer which receives light from one of the components, compensates for or transforms the delay distortion of the various wavelengths transmitted through the system, and provides the next component in the system with a compensated or transformed light beam. The dispersion transformer comprises means for receiving light from one of the components and dispersing/separating the light into the plurality of spatially separated beams which are directed onto the endface of a multimode optical fiber. The position of each beam on that end-face is a function of the velocity with which the light that forms the beam propagates through the transmission optical fiber. The multimode fiber is characterized in that it comprises a plurality of light-conducting channels, adjacent ones of which are separated by cladding regions having refractive indices lower than those of the adjacent light-conducting channels.

Journal ArticleDOI
TL;DR: In this paper, the broadening of a pulse propagating in a single mode optical fiber at the zero dispersion wavelength can be reduced by shifting that wavelength, based on the properties of the rms pulse width.

Journal ArticleDOI
L.G. Cohen1
01 Apr 1986

Journal Article
TL;DR: Results are given of an experiment which compared the three methods of pulse spectrum analysis and the PSA method has the advantage of being very simple and gives results that are consistent with the time domain and frequency domain methods.
Abstract: The pulse spectrum analysis (PSA) method of measuring fiber bandwidth has been suggested as an alternative to the frequency and time domain methods, but there is a paucity of information on the technique and very little data. In fact, we know of no measurement comparisons between the PSA method and the frequency and time domain methods. The PSA method has the advantage of being very simple and gives results that are consistent with the time domain and frequency domain methods. The International Electrotechnical Commission (IEC) recommends the PSA method, but the Electronics Industries Association (EIA) of the U.S.A. takes no position in this regard. This paper gives results of an experiment which compared the three methods.

Journal ArticleDOI
TL;DR: In this paper, the authors measured the dispersion of a concatenated dispersion-shifted singlemode fiber using a two-wavelength division multiplexing phase shift technique.
Abstract: Chromatic dispersion of a 1007 km concatenated dispersion-shifted single-mode fibre has been measured by a two wavelengths division multiplexing phase-shift technique utilising four laser diodes in the 13~16 ?m spectral region Measurement accuracies of dispersion and zero-dispersion wavelength were good and within ±0025 ps/km nm and ±03 nm, respectively The measured result of dispersion coincided with the arithmetic mean of those of the constituent fibres

Patent
Charles K. Asawa1
03 Apr 1986
TL;DR: In this paper, a spatial filter is used to selectively limit the angles of incidence of the light on the fiber, and operates in conjunction with the lens to launch light from one source at appropriate angles and points of excitation to excite higher-order modes in the fiber.
Abstract: An optical communication system in which at least two separate modal groups are launched into a single graded index transmission fiber. The system includes two light sources and a lens to focus the light sources into the transmission fiber. A spatial filter is used to selectively limit the angles of incidence of the light on the fiber, and operates in conjunction with the lens to launch light from one source at appropriate angles and points of excitation to excite higher-order modes in the fiber, and to launch light from the other source at appropriate angles and points of excitation to excite lower-order modes in the fiber.

Journal ArticleDOI
TL;DR: In this article, a multimode fiber having no P 2 O 5 in the core has been demonstrated which also exhibits uniform forward and cutback bandwidth-length dependence and improved resistance to the effects of hydrogen.
Abstract: Improvements in optical fiber fabrication made over the last two years using the outside vapor deposition (OVD) process are reported. Advances have been made in the areas of optical and mechanical performance for existing products, dopant changes, and single-mode fiber designs. A multimode fiber having no P 2 O 5 in the core has been demonstrated which also exhibits uniform forward and cutback bandwidth-length dependence and improved resistance to the effects of hydrogen. Data is also presented on a dispersion-shifted single-mode fiber made using the segmented core approach which has recently been put into production.

Patent
12 Jun 1986
TL;DR: An acousto-optic frequency shifter in which two cylindrical acoustic resonators driven 90° out of phase from one another are placed around a birefringent, single-mode optical fiber approximately three-quarters of a polarization beat length apart is described in this paper.
Abstract: An acousto-optic frequency shifter in which two cylindrical acoustic resonators driven 90° out of phase from one another are placed around a birefringent, single-mode optical fiber approximately three-quarters of a polarization beat length apart. The resonators interact with optical radiation propagating in one of two polarization modes of the fiber, the first to cross-couple two sidebands into the other polarization mode, and the second to suppress one of the sidebands in the cross-coupled mode and enhance the other, thereby creating a single sideband signal completely within the fiber.

Proceedings ArticleDOI
01 Nov 1986
TL;DR: In this article, a two-mode optical frequency shifter using coupling between the two optical spatial modes in a twomode glass fiber is reported, where the mode coupling is performed by acoustic flexural waves traveling along the fiber together with the optical waves.
Abstract: A novel all-fiber optical frequency shifter, using coupling between the two optical spatial modes in a two-mode glass fiber, is reported. The mode coupling is performed by acoustic flexural waves traveling along the fiber together with the optical waves. The acoustic wavelength for coupling to occur is equal to the beat length between the two optical spatial modes. Flexural waves of high amplitude are excited on the fiber by bonding the thin end of a tapered glass rod to the fiber while a piezoelectric transducer is bonded to the other end of the rod, which has a much larger cross section. A discussion of the acoustic behavior of the system is given. The calculated dispersion of the flexural waves guided by the fiber is compared with experimental measurements. Calculations prescribe the optimum excitation distribution at the thick end of the tapered rod. Experiments have shown 100 percent mode conversion at 8 MHz for 100 mW of electric input power. Measured suppression of both carrier frequency and image sideband was 35 dB.

Journal ArticleDOI
TL;DR: Using first-order perturbation theory, the optical power required to alter the phase-matched condition in a fiber directional coupler incorporating a nonlinear medium is calculated and applied to an optically controlled switch.
Abstract: A simple analysis is presented for calculating the change in the effective index of a guided mode in an optical fiber with reduced cladding surrounded by an optically nonlinear medium. Using first-order perturbation theory, the optical power required to alter the phase-matched condition in a fiber directional coupler incorporating a nonlinear medium is therefore calculated. This may then be applied to an optically controlled switch, the output of which may be transferred from one port to another by application of a high-intensity pulse. This method may be applied to other fiber components, for example, fiber gratings and polarizers.

Journal ArticleDOI
TL;DR: A comparative model of a He-Ne laser beam and an oxide glass leaky hollow fiber for a CO2 laser light beam and a chalcogenide glass leakY hollow fiber are studied and the critical value of the wall thickness for minimum attenuation is given.
Abstract: Very high interest in making a low-loss fiber for the infrared has been stimulated by important applications in optical communication, surgery, cutting, welding, and heat treatment. The leaky waveguide is one of the most promising types of future fiber in the infrared region where low-loss materials are not available or not suitable for making fibers (i.e., CO2 laser light λ = 10.6 μm). In this paper a comparative model of a He–Ne laser beam and an oxide glass leaky hollow fiber for a CO2 laser light beam and a chalcogenide glass leaky hollow fiber are studied. Measurements of attenuation, dependence of output power on diameter and angle, and the angular dependence of output angle vs input angle were made. The experimental data were compared with theoretical calculations, and the critical value of the wall thickness for minimum attenuation is given.