Modal analysis of the self-imaging phenomenon in optical fibers with an annular core

Abstract

We investigate the occurrence of self-images, or Talbot images, in a spatially multimode field that propagates along an optical fiber whose core has an annular-shaped cross section. By use of full-vectorial modal analysis, we study the effect of the transverse fiber dimensions on the self-imaging properties. According to our analysis, good self-images can be expected when the fiber core is thin and the modes are far from their cutoffs. However, as the core diameter is made larger to increase the number of modes available in the imaging, the general self-imaging properties tend to deteriorate.

An all fiber based Talbot self-imaging mirror device for phase-locking of a multi-fiber laser

“…The reimaging distance is much shorter than expected based on an analysis that uses the fiber core diameter as the periodicity length. Our reimaging length is on the same length scale as reported for annular fibers [24]. This is a clue that the coupled modes with azimuthal angle dependence are important contributors to the reimaging length which is only weakly dependent on the fiber core diameter.…”

Absorption studies of ring core double clad fiber

“…Glas and coworker has reported an M-profiled (or ring core) fiber, with undoped low index core surrounded by high index doped glass [1], and they claimed that the brightness and output power of the fiber can be as high as that of a conventional DCF. Modal behavior and occurrence of selfimages of this ring core fiber are studied both theoretically and experimentally [2][3][4][5]. This self-imaging property could be a potential candidate for coherent beam combination of the high power fiber lasers.…”

Talbot self-imaging and two-photon interference in ring-core fibers

“…It enables lens-free focusing, demonstrated for photons [3][4][5][6], electrons [7], atoms [8,9], and even large molecules [10,11]. Remarkably, this self-imaging maps onto the propagation of waves on cylindrical surfaces, where the periodicity of the angle coordinate replaces the periodic grating and where fractional Talbot revivals appear as spatially separated superpositions of the impinging wave packet [12][13][14].…”

“…In this letter, we report the self-imaging of single photons in thin ring-core fibers. These fibers support nearly transverse orbital angular momentum modes [14,22], which acquire an angular momentum-dependent phase while travelling along the fiber. At the revival length, all these phases coalesce, giving rise to the characteristic Talbot carpet, however rolled on the cylinder surface.…”