Guided modes of nonlinear slot waveguides

Guided modes of nonlinear slot waveguides are investigated for the first time and their unusual modal properties are demonstrated. Nonlinear phase shifts of slot waveguides induced by optical Kerr effect exhibit saturable behavior for strong optical intensity. This is because a self-localization effect of electromagnetic fields induced by optical Kerr effect is compensated with a field broadening originating from a unique confinement mechanism of slot waveguides. Nonlinear phase shifts on various structural parameters are thoroughly investigated. All the results presented in this letter are obtained by using a rigorous full-vector finite-element method to ensure accurate analysis.