Showing papers on "Dispersion-shifted fiber published in 1973"
TL;DR: Theoretical calculations supported by numerical simulations show that utilization of the nonlinear dependence of the index of refraction on intensity makes possible the transmission of picosecond optical pulses without distortion in dielectric fiber waveguides with group velocity dispersion.
Abstract: Theoretical calculations supported by numerical simulations show that utilization of the nonlinear dependence of the index of refraction on intensity makes possible the transmission of picosecond optical pulses without distortion in dielectric fiber waveguides with group velocity dispersion. In the case of anomalous dispersion (∂2ω/∂k2>0) discussed here [the case of normal dispersion (∂2ω/∂k2<0) will be discussed in a succeeding letter], the stationary pulse is a ``bright'' pulse, or envelope soliton. For a typical glass fiber guide, the balancing power required to produce a stationary 1‐ps pulse is approximately 1 W. Numerical simulations show that above a certain threshold power level such pulses are stable under the influence of small perturbations, large perturbations, white noise, or absorption.
2,509 citations
TL;DR: In this paper, fundamental optical scattering and absorption mechanisms have been identified which limit light transmission in fiber optical waveguide materials, which are intimately associated with the random structure in the liquid and glassy state.
Abstract: Fundamental optical scattering and absorption mechanisms have been identified which limit light transmission in fiber optical waveguide materials. These mechanisms, which are intimately associated with the random structure in the liquid and glassy state, are described and then used as a basis for comparing fiber optical waveguide materials. It is concluded that pure fused silica is a preferred waveguide material, having ultimate total losses of 1.2 dB/km at the Nd : YAG laser wavelength of 1.06 μ, 3.0 dB/km at the GaxAl1−xAs emission wavelength of approximately 0.8 μ, and 4.8 dB/km at the GaP : Zn, O emission wavelength centered at 0.7 μ.
188 citations
TL;DR: The acceptance angle of a fiber is increased remarkably by forming the fiber end spherically as discussed by the authors, and the coupling efficiency increased in this way is observed to be 5.2 times as high as that of a previous method.
Abstract: The acceptance angle of a fiber is increased remarkably by forming the fiber end spherically. It was demonstrated with light coupling into a fused‐silica‐core glass fiber from a mesa‐stripe‐geometry GaAs diode laser. The coupling efficiency increased in this way is observed to be 5.2 times as high as that of a previous method. The proper design of a fiber in this manner will lead to a light coupling efficiency higher than 90%.
131 citations
01 Oct 1973
TL;DR: In this paper, the authors measured the refractive index profile and impulse response of three low-loss multimode optical fibers, each 1 km long, and found that pulse dispersion of about 1.5 ns or less was observed in two of the fibers.
Abstract: The refractive-index profile and impulse response of three low-loss multimode optical fibers have been measured. Pulse dispersion of about 1.5 ns or less was observed in two of the fibers, each 1 km long.
79 citations
01 Oct 1973
TL;DR: In this paper, the authors showed that pulse broadening in the CGW-Bell-10 optical fiber showed very low dispersion ( 550 m) which is of practical significance.
Abstract: Previous measurements of pulse broadening in the CGW-Bell-10 optical fiber showed very low dispersion ( 550 m) which are of practical significance.
49 citations
TL;DR: In this paper, a low-loss fiber optical waveguide has been constructed having a pure fused silica core of 40μm diameter and a chemical-vapordeposited cladding layer of borosilicate glass 15-20 μm thick.
Abstract: A low‐loss fiber optical waveguide has been constructed having a pure fused silica core of 40‐μm diameter and a chemical‐vapor‐deposited cladding layer of borosilicate glass 15–20 μm thick. This core‐clad structure has an outer jacket of fused silica which serves to strengthen and protect the waveguide. Fabrication procedures and evaluation techniques are described. One fiber has been found to have a minimum optical attenuation of 13 dB/km at a wavelength of 0.7 μm. In the range 0.8–1.1 μm, where optical communications appear most promising, the attenuation varies between 18 and 22 dB/km with the exception of the OH absorption peak at 0.95 μm.
49 citations
TL;DR: The acceptance property of an optical fiber illuminated by coherent light is very simply found from meridional ray tracing, if the dimensionless quantity 2πρ{n12−n22}1/2/λ is much greater than unity.
Abstract: The amount of light power that is transmitted within a semi-infinite circular optical fiber when it is illuminated obliquely by a coherent beam of light is determined from an electromagnetic-theory analysis. The limit λ→0 is not classical geometric optics, i.e., not that found by tracing all rays along the fiber. Instead, the limit λ→0 corresponds to that of treating all rays as if they were meridional, i.e., as if they cross the fiber axis, ignoring rays skew to the axis. Thus, ray tracing is incorrect for fibers illuminated by coherent light. However, the acceptance property of an optical fiber illuminated by coherent light is very simply found from meridional ray tracing, if the dimensionless quantity 2πρ{n12−n22}1/2/λ is much greater than unity, where ρ is the fiber radius, λ the wavelength of light in vacuum, and n1, n2 the refractive indices of the fiber and its surround, respectively.
47 citations
TL;DR: In this paper, a new type of glass fiber is discussed, which is pure fused silica, and the cladding is a high silica content glass, and a light attenuation of approximately 20 dB/km was measured at a 632.8nm wavelength in the preliminary work.
Abstract: A new type of glass fiber is discussed. The core of the fiber is pure fused silica, and the cladding is a high‐silica‐content glass. This type of glass fiber has potentially the lowest attenuation of light propagation. A light attenuation of approximately 20 dB/km was measured at a 632.8‐nm wavelength in the preliminary work.
35 citations
TL;DR: In this article, the authors used a ray-vector approach to reconstruct the behavior of a hollow glass fiber in the presence of a plane-polarized laser source, by which the incident wavefront is decomposed into the component interactions of reflection and refraction with the fiber to give the emergent wavefronts.
Abstract: Irradiation of a hollow glass fiber, normal to its axis, by a plane-polarized laser source produces a coaxial interference pattern with distinctive features that can be related to the cross-sectional geometry of the fiber, providing a sensitive means of non-destructive monitoring of the outer radius and the ratio of inner and outer radii. The phenomena involved in this interpretation are explained and reconstructed by use of a ray-vector approach, by which the incident wavefront is decomposed into the component interactions of reflection and refraction with the fiber to give the emergent wavefronts. A number of measurements made on some samples demonstrate the proposals.
17 citations
TL;DR: In this paper, an oscillating mirror is used to deflect a laser beam with constant velocity across a fiber in order to measure the time interval during which the fiber intercepts the beam and casts a shadow on a photodetector.
Abstract: This paper describes a novel technique for monitoring the outside dimensions of clad or unclad optical fibers. An oscillating mirror is used to deflect a laser beam with constant velocity across a fiber in order to measure the time interval during which the fiber intercepts the beam and casts a shadow on a photodetector. For 110 μ fibers, individual measurements made every 1/60 sec are repeatable within a spread of ± 1% from the 330 μsec mean time interval (rms deviation ≈ ± 0.6%). Results are displayed in digital form, but can be converted to an analog signal for use in a servo loop to control the pulling rate of fiber drawing machines. An additional feature of the technique is that fibers with noncircular cross sections can be monitored by making sequential diameter measurements along orthogonal axes of the fiber.
14 citations
Patent•
19 Oct 1973
TL;DR: In this article, a p-n junction photodiode made of a graded bandgap semiconductor material is disclosed as a delay equalizing detector, where the gradient of the bandgap is made in such a manner that the different time delays of drifting charge carriers, generated by the absorption of different wavelengths at different depths in the graded band gap semiconductor, can be made to compensate for the time delays suffered by the optical energy at different wavelengths while propagating through the fiber.
Abstract: In optical fiber transmission, one of the causes of signal distortion (pulse broadening) stems from the fact that energy at different optical wavelengths travels at different velocities in the fiber material (material dispersion), and hence these wavelength components undergo different time delays while propagating through the fiber. In order to reduce this optical distortion, a p-n junction photodiode made of a graded bandgap semiconductor material is disclosed as a delay equalizing detector. The gradient of the bandgap is made in such a manner that the different time delays of drifting charge carriers, generated by the absorption of different wavelengths at different depths in the graded bandgap semiconductor, can be made to compensate for the time delays suffered by the optical energy at different wavelengths while propagating through the fiber.
TL;DR: It is shown that two different solutions are possible for designing guides that give a minimum of distortion due to dispersion, and that a dispersionless group index is possible for wavelengths at least as short as 0.77 micro.
Abstract: The effect of dielectric dispersion on pulse transmission through singly clad, cylindrical fibers is formulated in terms of the effective group index for the waveguide. It is shown that two different solutions are possible for designing guides that give a minimum of distortion due to dispersion. One solution uses fibers with low numerical aperture made from glasses with low dispersion; here for sufficiently long wavelengths minimum distortion is possible while the guide parameters limit conduction to the lowest order mode. It is predicted, for example, that a pulse of radiation in the lowest order mode with a carrier wavelength of 1.06 μ can be conducted with minimum distortion by a fiber made from commercially available, low dispersion glass. In the other solution the fiber is designed so that the HE11 mode provides an anomalous dispersive characteristic; this solution requires a high numerical aperture fiber with a core large enough to support the next higher order group of modes, namely the TE01, TM01, and HE21 modes. For this second solution, it is shown that a dispersionless group index is possible for wavelengths at least as short as 0.77 μ.
Patent•
18 Sep 1973
TL;DR: In this paper, an optical prism (or diffraction grating) is located in the path of the output wave exiting from the optical fiber, which angularly separates the various output wavelengths.
Abstract: An optical signal having a non-negligible bandwidth suffers a distortion while propagating in an optical fiber caused by the fact that signal components of different optical wavelengths propagate at different velocities through the fiber material, that is, by the dependence of refractive index upon wavelength (material dispersion). In order to compensate for this distortion, an optical prism (or diffraction grating) is located in the path of the output wave exiting from the fiber, which angularly separates the various output wavelengths. The angularly separated output waves are then incident upon a semiconductor P-N junction detector of the charge carrier drift type, such that the time delays of different wavelengths in the fiber are compensated by the different drift time delays of the different charge carriers generated by the different wavelengths absorbed in the drift region of the semiconductor.
Patent•
18 Sep 1973TL;DR: In this paper, a semiconductor charge carrier drift delay line is located in the path of the optical radiation emanating from the fiber, which is terminated by a charge carrier detector having an inherent gain.
Abstract: The propagation in an optical fiber of an incoherent optical signal pulse containing a moderate spread of optical wavelength carrier components, such as supplied to the optical fiber by a light emitting diode (LED) source, results in a broadening (distortion) of the optical output signal emerging from the fiber. This distortion is caused by the fact that different optical wavelengths propagate at different velocities through the fiber material, that is, by the dependence of refractive index upon wavelength (material dispersion); and also by the fact that different optical modes propagate at different velocities (mode dispersion). In order to compensate for such distortions, a semiconductor charge carrier drift delay line is located in the path of the optical radiation emanating from the fiber. Advantageously, this semiconductor delay line is depleted of bulk majority charge carriers by means of a reverse voltage bias and is terminated by a charge carrier detector having an inherent gain (such as an avalanche diode or a transistor). The delay line is arranged such that the time delays of different wavelengths or modes in the fiber are compensated by the different drift time delays of the charge carriers generated by the different wavelengths or modes absorbed at different locations in the semiconductor delay line. In the case of mode dispersion compensation, the s