The single-mode condition for semiconductor rib waveguides with large cross section

A comparison of the single-mode condition for semiconductor rib waveguides with large cross section obtained by the effective index method and the corrected formula proposed by Soref et al. [see IEEE Journal of Quantum Electronics, vol. 27, p. 1971, 1991] with experimental data is carried out. It is found that the effective index method is in a better agreement with Rickman's experimental data than the modified version. Moreover a stronger condition is proposed for single-mode design purposes.