Femtosecond laser nanoprocessing allows imprinting periodic subwavelength polarization-dependent nanostructures in fused silica and few other glasses [1]. The mechanism of their organization is still far from being completely understood [2]. Previously, transient nanoplasmonics model was proposed to explain the growth of nanoplasmas perpendicular to the laser polarization due to localized inhomogeneous multiphoton ionization [3]. In addition, Numerical modeling showed that initial nanometric inhomogeneities were required to start the process [4]. However, no detailed self-consistent models were proposed to simulate femtosecond laser-induced nanostructuring in glass. The influence of laser parameters, such as irradiation wavelength, laser pulse energy, number of pulses and laser polarization on the nanostructure characteristics is also still unclear. Figure 1 Electron density snapshot at the end of the pulse duration 240 fs (FWHM). The corresponding Fourier Transform (FT) of the image reveals the nanograting periodicity close to half the laser wavelength in glass. The pulse energy is fixed to be E = 500 nJ. Here, laser wavelength is 800 nm in air. Electron density is normalized by its critical value at 800 nm. Based on a detailed modeling, we investigate ultra-short laser-produced self-organization of volume nanogratings. Our calculation results show that this effect can be explained by using a full-vectorial 3D-Maxwell based approach coupled with the electron density equation. As a result, we examine the dynamics of ultrashort laser interaction with randomly distributed inhomogeneities embedded in glass. We compare the results of numerical modeling with the available experimental data . In particular, we show that the resulting structure periodicity strongly depends on laser wavelength. The orientation is defined by the electric field polarization. In terms of laser pulse energy, three regimes of modification experimentally investigated by Taylor et al. [5] are numerically confirmed. Finally, an explanation of the pulse number effect on the nanograting periodicity is proposed based on the mechanism of the nonlinear ionization memory [3], and a correlation ofthe concentration of inhomogeneities with the number of laser pulses is demonstrated. [1] M. Lancry, J. Canning, K. Cook, M. Heili, D. R. Neuville and B. Poumellec, “Nanoscale femtosecond laser milling and control of nanoporosity in the normal and anomalous regimes of GeO2 and SiO2 glasses”, Optical Materials Express, vol. 6, no. 2, (2016). [2] N. Bulgakova, V. Zhukov, S. Sonina, and Y. Meshcheryakov, “Modification of transparent materials with ultrashort laser pulses: What is energetically and mechanically meaningful?”, J. Appl. Phys., vol. 118, 233108, (2015). [3] P. Rajeev, M. Gertsvolf, C. Hnatovsky, E. Simova, R. Taylor, P. Corkum, D. Rayner, and V. Bhardwaj, “Transient nanoplasmonics inside dielectrics”, J. Phys. B: At. Mol. Opt. Phys., vol. 40, pp. 273-282, (2007). [4] R. Buschlinger, S. Nolte, and U. Peschel, “Self-organized pattern formation in laser-induced multiphoton ionization”, Phys. Rev. B, Vol. 89, 184306, (2014). [5] R. Taylor, C. Hnatovsky, and E. Simova, “Applications of femtosecond laser induced self-organized planar nanocracks inside fused silica glass”, Laser & Photon. Rev., vol. 2, no. 1-2, pp. 26-46, (2008).