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Showing papers on "Mode scrambler published in 1983"


Journal ArticleDOI
TL;DR: An electromagnetic modal theory for characterizing parabolic-index multimode fiber splices with either intrinsic or extrinsic mismatches predicts and experiment confirms a previously unreported periodic fluctuation in splice loss as a function of wavelength for intrinsic parameter mismatch.
Abstract: In this paper we present an electromagnetic modal theory for characterizing parabolic-index multimode fiber splices with either intrinsic or extrinsic mismatches. The theory agrees with previously published theoretical results for transverse offset using a uniform power distribution. It also agrees with new experimental measurements made with a long, spliced input fiber using a published, theoretical, steady-state modal power distribution. This modal theory predicts, and experiment confirms, a previously unreported periodic fluctuation in splice loss as a function of wavelength for intrinsic parameter mismatch. The analysis also predicts a large degree of mode mixing for transverse offset but negligible mode mixing for parameter mismatch in typical multimode fiber splices.

23 citations


Journal ArticleDOI
TL;DR: It is found that the magnitude of the compression of the total pulse response generated by mode coupling depends significantly on the details of the refractive-index profile of the test fiber.
Abstract: A computer program has been developed to study the total pulse response of optical fibers with profile ripple and central index depressions in the presence of arbitrary mode coupling. We have found that the magnitude of the compression of the total pulse response generated by mode coupling depends significantly on the details of the refractive-index profile of the test fiber.

15 citations


Journal ArticleDOI
Akihisa Tomita1, D. Marcuse1
TL;DR: In this paper, the authors found that single-mode fibers with depressed inner cladding show sharp resonant loss peaks near the fundamental mode cutoff wavelength where the core-guided mode starts to become a leaky mode.
Abstract: Single-mode fibers with depressed inner cladding show sharp resonant loss peaks near the fundamental mode cutoff wavelength where the core-guided mode starts to become a leaky mode. The magnitude of the loss peak exceeds 200 dB/km and was found to be extremely sensitive to fiber curvature. The phenomenon is attritubed to mode coupling between the core-guided mode and the discrete modes guided in the outer cladding.

14 citations


Patent
David F. Bowman1
31 May 1983
TL;DR: In this paper, a mode converter is disclosed which selectively generates a predetermined higher order mode(s) from an incident fundamental mode, which comprises a dielectric region having an effective-dielectric-constant/thickness profile which is the same as the amplitude profile of the desired higher order modes.
Abstract: A mode converter is disclosed which selectively generates a predetermined higher order mode(s) from an incident fundamental mode. This mode converter comprises a dielectric region having an effective-dielectric-constant/thickness profile which is the same as the amplitude profile of the desired higher order mode(s).

11 citations


Journal ArticleDOI
TL;DR: An analytical method of matching the mode of an input laser to the lowest-order mode of a passive resonant ring laser gyro is described, as are the steps in determining the location and focal length of cylindrical mode matching lenses.
Abstract: An analytical method of matching the mode of an input laser to the lowest-order mode of a passive resonant ring laser gyro is described, as are the steps in determining the location and focal length of cylindrical mode matching lenses. Results were obtained with no mode matching, with a compromise spherical lens, with horizontal mode matching only, and with the proper cylindrical mode matching lenses. Compared with no mode matching, the latter case shows that the amplitude of the lowest-order mode is increased ∼2.5 times. In addition, the number and intensity of higher-order modes are reduced to near zero, and the relative intensity of the lowest-order mode to the higher-order mode increased from ∼5 to ∼60 times greater.

6 citations


Journal ArticleDOI
F. Alard1, P. Sansonetti1
TL;DR: In this article, a simple derivation of the electric field and modal properties of the fundamental mode of single-mode fibres only from the results of the variable-aperture launch method performed on the fibre was reported.
Abstract: We report a simple derivation of the electric field and modal properties of the fundamental mode of single-mode fibres only from the results of the variable-aperture launch method performed on the fibre.

6 citations


Journal ArticleDOI
TL;DR: In this paper, a 2 × 2 optical star coupler is fabricated using this mode scrambler, and a stable branching ratio is realized with an excess insertion loss of 2.7 dB.
Abstract: A novel mode scrambler for multimode optical waveguides is proposed to stabilise branching characteristics against the mode excitation conditio. A 2 × 2 optical star coupler is fabricated using this mode scrambler, and a stable branching ratio is realised with an excess insertion loss of 2.7 dB.

5 citations


Journal ArticleDOI
TL;DR: In this paper, the transmission properties of a two-mode system with uniform mode coupling are analyzed in detail in the time domain, and the impulse response of the system is found analytically taking mode dispersion and frequency-dependent mode coupling into account.
Abstract: The transmission properties of a two-mode system with uniform mode coupling are analyzed in detail in the time domain. The impulse response of the system is found analytically taking mode dispersion and frequency-dependent mode coupling into account. By calculating the pulse response when the system is excited with a Gaussian pulse, the effective mode dispersion and energy coupling are determined. Through this analysis it is shown that the coupling will introduce an oscillating tail on the excited mode with a duration equal to the polarization-mode dispersion and a magnitude determined by the ratio between the birefringence and the mode-coupling coefficient. For polarization-preserving fibers this tail may be several nanoseconds long, but the magnitude is likely to be small. The presence of mode coupling reduces the effective mode dispersion but causes the state of polarization to be unstable. Finally it is shown that material dispersion will not affect the polarization-handling properties of the system but leads to oscillating responses from the individual modes.

5 citations


Journal ArticleDOI
TL;DR: In this paper, a coherent states method is used to investigate the mode coupling coefficients in the most general buttjoint problem for two multimode general square-law-index optical waveguides, when two different waveguide with elliptical cross-sections are to be butt-jointed with axis displacement, tilt and some turning of symmetry axes with respect to each other.
Abstract: A coherent states method is used to investigate the mode coupling coefficients in the most general buttjoint problem for two multimode general square-law-index optical waveguides, when two different waveguides with elliptical cross-sections are to be butt-jointed with axis displacement, tilt and some turning of symmetry axes with respect to each other. The explicit expressions for the mode coupling coefficients and recurrence relations for the mode overlap integrals are obtained; the sum rules for the mode coupling coefficients are formulated and a method of experimental data analysis is proposed for this general problem. The method of calculating mode coupling coefficients is proposed for the case of the butt-joint problem when the waveguide cross-sections are only partially overlapping and then it is used to investigate the influence of misalignment on mode power distribution and pulse dispersion in the second waveguide. The experimental data are compared and it is shown that the coupling coefficients obtained in square-law-index model can be used in dispersion calculations forα-profile fibres in the case when the valueα is not far from the valueα=2.

4 citations


Journal ArticleDOI
TL;DR: It is found that slowly varying profile components can be correctly estimated from DMD results even in the presence of substantial mode coupling.
Abstract: The manner in which the differential mode delay (DMD) pulse response is affected by ellipticity- and microbending-induced mode coupling has been analyzed numerically. We have considered both a fiber profile containing a central index dip and fiber profiles with sinusoidal ripples. We find that slowly varying profile components can be correctly estimated from DMD results even in the presence of substantial mode coupling.

3 citations


Journal ArticleDOI
TL;DR: In this article, a new method of passive source ranging in a layered waveguide has been proposed, where the mode-filtering processor was used to process the field data of a vertical array in order to obtain individual modes.
Abstract: The conventional beamforming technique could not be used for source locating in waveguide owing to the modal interference structure of the field. In this paper a new method of passive source ranging in a layered waveguide has been proposed. The mode‐filtering processor was used to process the field data of a vertical array in order to obtain individual modes. The source range information can be extracted by measurement of three individual mode phases. The source range was expressed in terms of the “mode interference distance” as following: r = LijDij + Δrij; Δrij = Dij(δφij/2π), where Lij is a certain integer; δφij is the phase difference of the ith mode and the jth mode; Dij is the “mode interference distance” defined by: Dij = 2π/(ki − kj); ki is the wavenumber of the ith mode given by a numerical mode code. The information of Lij can be estimated by means of comparing the phase of the jth mode with another mode, say mth mode, and then Lij was estimated by solving the following equation: (δφij/2π) = Fra...

Journal ArticleDOI
TL;DR: The relations between the far-field intensity distribution and the corresponding modal power distribution resulting from differential excitation are employed to determine the index profile of a multimode fiber.
Abstract: The relations between the far-field intensity distribution and the corresponding modal power distribution resulting from differential excitation are employed to determine the index profile of a multimode fiber. The modal propagation constant and the modal time delay are determined from the far-field distribution, eliminating the need for ultrafast sources and detectors, required in the direct time-delay measurements. The temporal impulse response is reconstructed numerically from the modal time-delay distribution for specific excitation conditions.