Showing papers on "Equilibrium mode distribution published in 1976"
TL;DR: In this article, a simple method for direct measurement of the V-value for a single-mode optical fiber was proposed, which consists of measurement of loss peaks, corresponding to cutoff wavelengths of the higher modes, which are easily observed for a fibre with a bend.
Abstract: A simple method is proposed for the direct measurement of the V-value for a single-mode optical fibre. This method consists of measurement of loss peaks, corresponding to cutoff wavelengths of the higher modes, which are easily observed for a fibre with a bend.
63 citations
TL;DR: Design criteria for the construction of a modified parabolic-index fiber with intentional mode coupling is presented and mode coupling serves the purpose of reducing multimode pulse dispersion and is accomplished by introducing carefully designed index fluctuations into the fiber core or by controlled “random” bends of the fiber axis.
Abstract: We present design criteria for the construction of a modified parabolic-index fiber with intentional mode coupling. Mode coupling serves the purpose of reducing multimode pulse dispersion and is accomplished by introducing carefully designed index fluctuations into the fiber core or by controlled “random” bends of the fiber axis. Radiation losses due to mode coupling can be minimized by terminating the parabolic-index fiber core in an abrupt index discontinuity. The additional modes introduced by this step must be filtered out by periodic mode filters that consist of parabolic-index fiber sections without the refractive-index step.
11 citations
TL;DR: In this article, a four terminals type piezo-electric transducer was used to observe the phase of vibration of each mode at the end of the rod and to classify directly the wave modes.
Abstract: Experimental study on the high frequency elastic wave mode propagating in a long circular aluminum rod was executed using new devices. A four terminals type piezo-electric transducer was used to observe the phase of vibration of each mode at the end of the rod and to classify directly the wave modes. Experimental results are as follows. Good coincidence between the theoretical group velocity and the experimental propagating velocity in each mode is obtained within the experimental errors. The mode coupling phenomenon is observed at the critical frequency, and also observed in the condition of the F2 mode type impulse. The directions of the neutral surface of vibration in the F1 modes are different from each other. The directions in the F1(2) mode and the F1(3) mode are perpendicular and parallel to the direction in the F1(1) mode respectively, and each direction does not change with a change of frequency.
1 citations
TL;DR: In this article, the stabilization of alternating strong and weak mode patterns of the 6328 A light from a Brewster window He-Ne laser in an increasing axial magnetic field is studied.
Abstract: The stabilization of alternately strong and weak mode patterns of the 6328 A light from a Brewster window He-Ne laser in an increasing axial magnetic field is studied. One of the necessary conditions for the appearance of this pattern is newly discovered; that is, the Zeeman splitting has to be nearly equal to an odd-number times the adjacent mode separation. This condition is deduced from a mode interaction scheme involving four kinds of interactions. The interaction between Zeeman components and mode interactions in a standing-wave resonator laser are represented by a parallelogram, and the effect of Brewster windows and the adjacent mode interactions are represented by interactions between parallelograms. This scheme is formulated in order to calculate the mode intensities numerically and a good agreement with the observations is obtained.