Comparative analysis of transverse mode instability in single-clad and double-clad fibers

Abstract

This work presents a comparative study between single-clad (SCF) and double-clad (DCF) fiber designs, focusing on modal propagation and tolerance to the transverse mode instability (TMI). Analytical solutions for LPmn modes and numerical simulations are used to analyze the transverse intensity distributions and the influence of structural parameters on the TMI onset threshold in high-power fiber lasers. Results show that DCFs exhibit greater tolerance to TMI, attributed to the broader transverse mode distribution in lower-index regions, which enhances optical confinement and thermal dissipation.