Analysis of polarization-mode coupling by acoustic torsional waves in optical fibers
Coupling of polarization modes of the LP01 spatial mode by acoustic torsional waves in an optical fiber is considered in detail. Analytic expressions of the coupling coefficients based on the combined effects of birefringence and photoelastic contributions are found. The results show that for regular fibers the birefringence component is the larger of the two. By the use of higher radial orders of the acoustic torsional modes, the coupling efficiency can be increased.
In this paper we study the multivariate ANOVA decomposition for $1$-periodic functions on the torus. In particular we use the integral projection operator that leads to the classical ANOVA decomposition. Relationships between the Fourier coefficients of the function and its ANOVA terms lead to special frequency index sets and give an understanding of the decomposition working in the frequency domain. Moreover, we consider the truncated ANOVA decomposition and provide error bounds for approximation in $\mathrm{L}_\infty$ and $\mathrm{L}_2$. We present an approximation method based on the truncated decomposition with regard to a superposition dimension $d_s$.