Modeling of nonlinear responses in BK7 glass under irradiation of femtosecond laser pulses

Abstract

In this paper, the nonlinear response in BK7 glass sample is investigated under irradiation of 200 fs laser pulses at 800 nm wavelength by using of transmission measurement method. Nonlinear transmission is observed for incident pulse energies above 37 µJ. A theoretical model based on simultaneously absorption of one, two and three-photon absorption is presented. The contribution of free-carriers absorption is also included on the model. The differential equation is solved analytically. The experimental results and predictions of theoretical model are in good agreement. The values of three-photon absorption coefficient and free-carriers absorption cross-section are reported.

Processing of optical glasses by single, 34 fs pulses in the strong field ionization domain: ablation characteristics and crater morphology

“…Data available in the relevant literature are compiled in Table 2. Our figures match fairly well with those reported for commercial glasses [35,36,38,39]. The α 3 value of the ULE glass [37] is four orders of magnitude smaller as compared to the more commercial glasses as measured by the same authors [35,36,38,39] therefore it is not considered in the forthcoming analysis.…”

“…Our figures match fairly well with those reported for commercial glasses [35,36,38,39]. The α 3 value of the ULE glass [37] is four orders of magnitude smaller as compared to the more commercial glasses as measured by the same authors [35,36,38,39] therefore it is not considered in the forthcoming analysis. At the other extreme Grehn [14] derived α 3 values of two orders of magnitude higher than ours for multiple component silicate glasses both from transmission [25] and ablation [14] measurements by working in the intensity ranges of 2 × 10 11 -4 × 10 11 W/cm 2 and 1.7 × 10 13 -1.8 × 10 14 W/ cm 2 , respectively.…”

“…When discussing the interaction of ultrashort pulses with glasses [25,[35][36][37][38][39][40] there are approaches considering both two-, three-and four-photon absorption depending on the actual bandgap. Since the bandgaps of the glasses investigated are around 4 eV, when fitting Eq.…”

“…Authors report effects of highly ionizing ultrashort pulses on the optical response of silica focusing on nonlinear absorption [12,25], nonlinear refractive index [25,26], plasma reflectivity [5,6] in a broad range of pulse durations from 7 fs to 4 ps. Commercial multicomponent borosilicate and crown glasses may serve as cheaper and more accessible alternatives, however, investigations in the literature related to glasses using few-cycle pulses are scarce [11,27,28]: the majority of the studies were performed with longer and moderate-intensity pulses examining either material [14,17,19,[29][30][31][32][33][34], or optical [25,26,[35][36][37][38][39][40] response. Therefore, available data for the description of the aftermath of strong-field ionization in the ablation process of glasses is inconveniently deficient.…”

Microfabrication and Surface Functionalization of Soda Lime Glass through Direct Laser Interference Patterning

“…One of the most distinguishing features of two-photon absorption is that the amount of absorbed power in a thin layer of the medium is proportional to the square of the light intensity (or power), while, in one-photon absorption, the ratio of absorption depends linearly with respect to intensity [ 49 ]. Therefore, considering a Gaussian beam, the absorption rate drops quadratically, moving from the center toward the periphery of the beam and any linear variation in the power would produce a quadratic variation of the absorption coefficient and, therefore, of the ablation depth [ 50 ].…”