Abstract

Self-focusing in a medium of intensity-dependent refractive index has been extensively studied since the 60's. A particular case of self-focusing is the self-guided mode for which the natural tendency of a light beam to diffract is exactly compensated by the presence of a positive Kerr-law nonlinearity. A self-guided mode can also be seen as a mode of the waveguide it induces^[1]. In this paper, we present a study of the HE_1m self-guided modes of circular cross-section in an ideal (homogeneous, non-saturable and without absorption) Kerr-law nonlinear medium. Although scalar theory predicts, within its domain of validity, that these modes are unstable, our exact vectorial analysis shows that they are stable to cylindrical perturbations. This result. is in accordance with the recent work of Chen and Snyder who established the need of taking into account the polarization of self-guided cylindrical TE and TM modes^[2].

© 1991 Optical Society of America