其他名称：
24-22-00290
项目负责人：
Smirnov Nikita
发表日期：
2024
主持机构：
P.N.Lebedev Physical Institute of the Russian Academy of Sciences,
国家：
俄罗斯
开始日期：
2024
结束日期：
2025
简介：
The processing of materials by ultrashort laser pulses with a wavelength of the mid-IR range (2-6 μm) has practically not been studied to date, but at the same time it has great potential for processing narrow-gap semiconductors that are transparent to IR radiation, especially silicon, which is the main semiconductor material for countless applications, including photovoltaics and microelectronics. Thus, with the laser IR radiation, it is possible to produce direct laser modification in the bulk of the material. At the same time, it was shown in a number of works that under direct laser action on the volume of silicon by ultrashort laser pulses, a number of difficulties arise with the delivery of the energy necessary for laser modification of the material, associated with an extremely high nonlinear refractive index of silicon (n2≈3.1*10-14 cm2 W- 1 at a wavelength of 1.3 μm), implying the formation of a nonlinear focus in the prefocal region and the appearance of a filament, in this regard, it is very important to know the nonlinear characteristics of the material at the laser interaction wavelength.$To understand the physics of the process, it is important to know the nonlinear optical properties of the material and the mechanisms that determine the absorption of an ultrashort laser pulse in a material. It has been demonstrated in a number of works that when ultrashort pulses with a wavelength in the IR range (1.2-2 μm) are exposed to silicon, the dominant mechanism of absorption of femtosecond laser pulses is multiphoton ionization (Grojo, D., Leyder, S., Delaporte, P., Marine , W., Sentis, M., & Utéza, O. (2013) Long-wavelength multiphoton ionization inside band-gap solids Physical Review B, 88(19), 195135). At present, in almost all works where volume modification of silicon was carried out, laser radiation sources with wavelengths up to 2 μm were used (Chambonneau, M., Grojo, D., Tokel, O., Ilday, F. Ö., Tzortzakis, S. , & Nolte, S. (2021), In-Volume Laser Direct Writing of Silicon—Challenges and Opportunities, Laser & Photonics Reviews, 15(11), 2100140.). For the same range, the nonlinear characteristics of silicon are well known. For example, (Bristow, A. D., Rotenberg, N., & Van Driel, H. M. (2007), Two-photon absorption and Kerr coefficients of silicon for 850–2200 nm. Applied Physics Letters, 90(19), 191104.) present results of measuring multiphoton absorption coefficient and nonlinear refractive index in silicon for the range of 850-2200 nm. The value of these coefficients determines the radiation intensity, starting from which nonlinear optical effects appear in the material, and is an extremely important parameter for laser exposure. At the same time, there are no works in which the interaction of ultrashort laser pulses with long wavelengths is considered in detail. There are a few works that consider individual wavelengths, for example, 4.6 µm (Mareev, E., Obydennov, N., & Potemkin, F. (2023). Dynamics of the Femtosecond Mid-IR Laser Pulse Impact on a Bulk Silicon. In Photonics (Vol. 10, No. 4, p. 380). MDPI).$Thus, the novelty of this project lies in conducting new experimental studies aimed at studying the interaction of ultrashort femtosecond laser pulses in the mid-IR range (2-6 μm) with silicon at hard focusing (NA>0.2). The mechanisms of multiphoton ionization of silicon depending on the wavelength of laser radiation will be considered. Abstract—The spectral transformation of mid-IR laser pulses passing through a thin silicon wafer with tight focusing of laser radiation is considered.
专业领域：
其他
语种：
英语
