Abstract

The confinement of optical pulses in nonlinear inhomogeneous slab waveguides is theoretically derived and parametrically investigated with a set of controlling parameters consisting of optical wavelength, slab thickness, percentage of doping, ratio of slab thickness to optical wavelength, film nonlinearity, and injected power.^1,2 The model consists of a thin optical dielectric film sandwiched between semi-infinite dielectrics (substrate and cover). The three layers possess a Kerr-like nonlinearity. The electric fields, and consequently the powers trapped in each slab, are derived under simple, but accurate, forms. The confinement factor is as follows: C = P_f/(P_f + P_c + P_s), where P_f, P_c, and P_s are, respectively, the trapped power through the film, the cover, and the substrate. The correlation of C and the ratio d/λ (2d is the slab thickness and λ is the optical wavelength) is obtained under a simple series form with coefficients that depend on the set of controlling parameters. Two different slabs (AlGaAs and SiO₂–GeO₂) are tested and compared. Under any common set of controlling parameters, the AlGaAs waveguide possesses a high confinement coefficient compared to the GeO₂–SiO₂ waveguide. The ultimate confinement is obtained if the product of film refractive index and its nonlinear coefficient equals the product of the substrate.

© 1990 Optical Society of America