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We use frequency domain holography (FDH) to spatio-temporally visualize the laser-matter interaction caused by the optical Kerr effect and plasma in flexible Corning® Willow® Glass in a single-shot. 

We measure the nonlinear index of refraction (n2) and investigate plasma dynamics in flexible Corning® Willow® Glass using single-shot Frequency Domain Holography (FDH). Flexible glass has received a lot of attention recently due to various applications such as 3-D photonics and wearable devices. Femtosecond laser micromachining (FLM) is a viable tool to fabricate these devices because of minimal thermal effects and thus enables fabrication of small and clean 3-D structures. To control and understand the underlying dynamics of FLM, ultrafast visualization of plasma and optical Kerr effect is important. FDH is a robust femtosecond time-resolved technique in which chirped reference and probe pulses centered at 404 nm are used to measure and visualize the plasma and Kerr effect produced by an intense, ultrashort pump pulse centered at 808 nm. Using FDH, we study laser-matter interactions in Willow Glass and measure its n2 to be 3.41 +/-0.08 ×10-16 cm2/W and visualize the plasma dynamics. 

We model laser filamentation in ZnSe in the mid-infrared (Mid-IR, wavelengths λ = 4 and 6 μm) and the long-wavelength infrared (LWIR, λ = 8 and 10 μm) using carrier-resolved unidirectional pulse propagation equations (UPPE). We predict an unprecedented propagation regime at λ = 8 μm that supports light bullets, which are spatio-temporally non-spreading electromagnetic pulses. Furthermore, in contrast to the previous report in air in the mid-IR, we predict that LWIR light bullets in solids critically rely on plasma-mediated dispersion, which dynamically evolves during multiphoton and tunneling ionization as peak plasma densities reach ρ 6.6 ×10^18 cm-3 . Finally, the plasma-assisted light bullets propagate with sub-cycle pulse durations and peak intensities I = 1.1 ×10^12 W /cm^2 , making them useful for high-harmonic generation and attosecond pulse generation. 

We visualize material modification during laser micromachining, in particular, laser waveguide fabrication in flexible Corning® Willow® Glass via time-resolved interferometry, and single-shot frequency-domain holography which is a robust technique for studying permanent material change/damage.