Equilibrium mode distribution

About: Equilibrium mode distribution is a research topic. Over the lifetime, 928 publications have been published within this topic receiving 14939 citations.

Propagation in radially-inhomogeneous single-mode fibre

Abstract: The propagation of electromagnetic waves along a radially-inhomogeneous single-mode optical fibre with small index difference between core and cladding is studied. As in the case of the step-index fibre the propagation modes are weakly guided and their transverse fields are essentially polarized in one direction. The simple field descriptions and characteristic equation obtained here enable mode spot size and bending loss to be determined and are useful for practical design work of radially-inhomogeneous single-mode optical fibres.

Excitation of the dominant mode of a round fiber by a Gaussian beam

Abstract: The excitation of the dominant HE 11 mode of a round optical fiber by a gaussian beam has been calculated. The calculation is based on the assumption that reflected waves can be neglected. It is thus applicable only to fibers with low index difference between core and cladding. It is found that optimum excitation of the HE 11 mode is achieved for loosely guided beams if the product of the beam half-width w times the radial decay constant γ of the HE 11 mode outside of the guide is unity, γw = 1. For tightly coupled modes 2½w must be equal to the core radius in order to achieve optimum excitation. As much as 99 percent of the power can be transferred to the HE 11 mode. Also investigated are the effects of an off-set or tilted beam on the mode excitation. The mode excitation drops to 36 percent if the amount of off-set equals the beam half-width. The effect of tilts depends on the parameter kd, free space propagation constant times core radius of the fiber. For small values of kd or loosely guided modes, the mode excitation is very sensitive to tilts of the gaussian beam. As long as the HE 11 mode is the only mode that can propagate, increasing values of kd lead to less sensitivity with respect to tilts. For multimode operation of the fiber, the sensitivity to tilts increases with increasing values of kd. The minimum of tilt sensitivity coincides with the minimum spot size of the guided mode.

Measurement of birefringence correlation length in long, single-mode fibers

Abstract: Measurements of birefringence correlation length performed on long single-mode telecommunication fibers are reported. The proposed technique relies on the statistical properties of the backscattered-field polarization, which was measured by means of a polarization-sensitive optical time-domain reflectometer. Experimental results are reported that show good agreement with the underlying theory based on stochastic differential equations.

Normalization of single-mode fibers having an arbitrary index profile

Abstract: A method is proposed whereby the propagation characteristics of a single-mode fiber having an arbitrary refractive-index profile may be expressed in terms of a newly defined equivalent step-index profile. The theory is based on the fact that the field distribution of the HE11 mode of a fiber closely resembles the Gaussian profile. The method makes it possible to characterize a fiber from a simple measurement of the HE11 mode spot size without making difficult index profile and core radius measurements. It is also found that the step-index distribution is suitable for single-mode fibers.

Scaling the effective area of higher-order-mode erbium-doped fiber amplifiers.

Abstract: We demonstrate scaling of the effective area of higher-order mode, Er-doped fiber amplifiers Two Er-doped higher-order mode fibers, one with 3800 μm2 Aeff in the LP0,11 mode, and one with 6000 μm2 effective area in the LP0,14 mode, are demonstrated Output beam profiles show clean higher order modes, and S2 imaging measurements show low extraneous higher order mode content CW and pulsed amplifier experiments are reported Nanosecond pulses are amplified to 05 mJ pulse energy with 05 MW peak power