Lanthanum titanate nanoparticles of La2-xAxTi2O7 (the undoped is denoted by LTO and the monodoped with Bi, Ce, and Y is denoted by LBTO, LCTO and LYTO, respectively) were prepared by sol-gel route. X-ray diffraction (XRD) reveals that these compounds crystallize as a monoclinic layered perovskite-like structure with a space group P21. UV-visible diffuse reflectance spectroscopy was employed to characterize the optical properties and hence the dispersion parameters. Optical transmittance and reflectance were investigated to obtain more in-depth insight into the optical properties and optoelectronic behavior of studied nanoparticles. The data collected reveal that the samples have a wide band gap (Eg) that varies between 3.50 and 3.88 eV. By introducing the Ce ion into the host matrix LTO, the optical gap energy was decreased from 3.69 to 3.51 eV despite a low doping content of 5%. However, the Urbach energy (EU) was increased from 0.28 to 0.85 eV. The dispersion of the refractive index has been studied in terms of a single oscillator by the Wemple and Di-Domenico (WDD) model as well as important parameters such as the dispersion energy Ed, the excitation energy Eo and the third-order nonlinear (NL) optical susceptibility χ(3). Ed and E0 parameters have a crucial role in identifying the characteristics of optical materials and allow the calculations of the factors required for the design of spectral dispersion and optical communication devices.