D. Gloge

Bio: D. Gloge is an academic researcher from Bell Labs. The author has contributed to research in topics: Multi-mode optical fiber & Optical fiber. The author has an hindex of 5, co-authored 5 publications receiving 1979 citations.

Weakly guiding fibers.

Abstract: Thin glass fibers imbedded into a glass cladding of slightly lower refractive index represent a promising medium for optical communication. This article presents simple formulas and functions for the fiber parameters as a help for practical design work. It considers the propagation constant, mode delay, the cladding field depth, and the power distribution in the fiber cross section. Plots vs frequency of these parameters are given for 70 modes

Dispersion in Weakly Guiding Fibers

Abstract: Optical signals transmitted through cladded glass fibers are subject to delay distortion because of (1) dispersion in the material, (2) dispersion caused by the waveguide characteristic, and (3) delay differences between modes. We isolate these effects and evaluate their significance for cases of practical interest. These concern fibers in which the refractive index of the cladding is only slightly lower than that of the core.

Bending loss in multimode fibers with graded and ungraded core index.

Abstract: Parabolic grading of the core index in a multimode fiber (Selfoc) diminishes mode dispersion and interface loss. This paper shows that this grading affects the mode volume and the loss in bends very little, if the index difference of the graded core (between the core axis and the cladding) is twice that of the homogeneous core. Curvature radii of several centimeters are tolerable. Mode coupling (or ray deflection) in random bends is slightly decreased by grading. Both the graded and the homogeneous multimode fiber are particularly sensitive to certain critical deviations of the guide axis from straightness. These deviations must be less than a fraction of a micrometer in order that catastrophic mode loss be avoided.

GaAs Twin-Laser Setup to Measure Mode and Material Dispersion in Optical Fibers.

Abstract: Two synchronously self-pulsing GaAlAs lasers, emitting at slightly different wavelengths, are combined in a setup which evaluates mode and material dispersion in multimode fibers. The results show that material dispersion which causes a pulse broadening of 3.6 ns/km, which may represent a serious limit to the bit rates achievable in a multimode fiber system using an LED source.

Direct measurement of the (baseband) frequency response of multimode fibers.

Abstract: Incoherent light, transmitted via multimode fibers, represents a potential carrier for information that is directly modulated on the light envelope. The amplitude and phase characteristics of the envelope (baseband) signal are affected by the fiber waveguide because of group delay differences among the modes. We report on a technique that determines the baseband frequency response of the fiber system by comparing the beat spectra of light from a free-running laser before and after transmission through the fiber. As an example, we describe the measurement of 30 m of cladded multimode fiber. The 3-dB bandwidth was 700 MHz, somewhat larger than predicted on the basis of the computed group velocity differences.

Transmission of stationary nonlinear optical pulses in dispersive dielectric fibers. I. Anomalous 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.

Capacity Limits of Optical Fiber Networks

Abstract: We describe a method to estimate the capacity limit of fiber-optic communication systems (or ?fiber channels?) based on information theory. This paper is divided into two parts. Part 1 reviews fundamental concepts of digital communications and information theory. We treat digitization and modulation followed by information theory for channels both without and with memory. We provide explicit relationships between the commonly used signal-to-noise ratio and the optical signal-to-noise ratio. We further evaluate the performance of modulation constellations such as quadrature-amplitude modulation, combinations of amplitude-shift keying and phase-shift keying, exotic constellations, and concentric rings for an additive white Gaussian noise channel using coherent detection. Part 2 is devoted specifically to the "fiber channel.'' We review the physical phenomena present in transmission over optical fiber networks, including sources of noise, the need for optical filtering in optically-routed networks, and, most critically, the presence of fiber Kerr nonlinearity. We describe various transmission scenarios and impairment mitigation techniques, and define a fiber channel deemed to be the most relevant for communication over optically-routed networks. We proceed to evaluate a capacity limit estimate for this fiber channel using ring constellations. Several scenarios are considered, including uniform and optimized ring constellations, different fiber dispersion maps, and varying transmission distances. We further present evidences that point to the physical origin of the fiber capacity limitations and provide a comparison of recent record experiments with our capacity limit estimation.

Optical fiber long-period grating sensors.

Abstract: We present a novel class of highly sensitive sensors based on long-period fiber gratings that can be implemented with simple and inexpensive demodulation schemes. Temperature, strain, and refractive-index resolutions of 0.65 °C, 65.75 μ∈, and 7.69 × 10−5, respectively, are demonstrated for gratings fabricated in standard telecommunication fibers.

Optical fibre long-period grating sensors: characteristics and application

Abstract: Recent research on fibre optic long-period gratings (LPGs) is reviewed with emphasis placed upon the characteristics of LPGs that make them attractive for applications in sensing strain, temperature, bend radius and external index of refraction. The prospect of the development of multi-parameter sensors, capable of simultaneously monitoring a number of these measurands will be discussed.

Modeling erbium-doped fiber amplifiers

Abstract: Erbium-doped fiber amplifiers are modeled using the propagation and rate equations of a homogeneous two-level laser medium. Numerical methods are used to analyze the effects of optical modes and erbium confinement on amplifier performance, and to calculate both the gain and amplified spontaneous emission (ASE) spectra. Fibers with confined erbium doping are completely characterized from easily measured parameters: the ratio of the linear ion density to fluorescence lifetime, and the absorption of gain spectra. Analytical techniques then allow accurate evaluation of gain, saturation, and noise in low-gain amplifiers (G >