A Study of the Nonlinear Optical Properties of Polydimethylsiloxane Interacting with 1030 nm Femtosecond Laser Pulses

Abstract

The characteristics of the nonlinear optical interaction of femtosecond laser pulses (250–2500 fs) at a wavelength of 1030 nm with polydimethylsiloxane (PDMS) were investigated using the Z-scan technique. It is demonstrated for the first time that the radiation attenuation in PDMS can be described within the peak intensity range up to 0.27 TW/cm² by five-photon absorption with a coefficient of β₅ = 750 ± 90 cm⁷/TW⁴. Nonmonotonic dependences of both nonlinear absorption and the nonlinear refractive index on the pulse duration were observed to exhibit peaks at 350 and 500 fs, respectively. These features are attributed to the competition between multiphoton and avalanche ionization processes. These findings provide an important foundation for high-precision laser modification of PDMS.