Slow light nanocoatings for ultrashort pulse compression

Abstract

Transparent materials do not absorb light but have profound influence on the phase evolution of transmitted radiation. One consequence is chromatic dispersion, i.e., light of different frequencies travels at different velocities, causing ultrashort laser pulses to elongate in time while propagating. Here we experimentally demonstrate ultrathin nanostructured coatings that resolve this challenge: we tailor the dispersion of silicon nanopillar arrays such that they temporally reshape pulses upon transmission using slow light effects and act as ultrashort laser pulse compressors. The coatings induce anomalous group delay dispersion in the visible to near-infrared spectral region around 800 nm wavelength over an 80 nm bandwidth. We characterize the arrays’ performance in the spectral domain via white light interferometry and directly demonstrate the temporal compression of femtosecond laser pulses. Applying these coatings to conventional optics renders them ultrashort pulse compatible and suitable for a wide range of applications.

Time Reversal Differentiation of FDTD for Photonic Inverse Design

“…Nanostructures with spatially variant group delays are frequently employed in meta-optics to engineer behavior over a frequency band, such as achromatic metalenses, which focus light within a given frequency range to a single focal point . Such nanostructures are designed through dispersion engineering, in which the transmission phase is designed to have a specific dependence on the illumination frequency, a process that typically entails the simulation of a nanostructure behavior over a dense set of frequencies, followed by polynomial regression on the transmitted spectral phase profile. ,, A linear phase dependence in the spectral phase represents a group delay on the pulse envelope, enabling such behavior to be engineered more directly in the time domain. To our knowledge, such time-domain group delay topology optimization has only been done in the context of metasurfaces by Yasuda and Nishiwaki .…”

All-Glass 100 mm Diameter Visible Metalens for Imaging the Cosmos

“…30 As fused silica has relatively high laser-induced damage threshold (LIDT) compared to most optical glasses, 46 we anticipate that the all-glass metasurface platform will be useful in versatile coating options and high-power laser applications not only for focusing but also for polarization manipulation 28 and pulse compression. 47,48 Furthermore, their resilience under extreme environmental conditions highlights their suitability for remote imaging in harsh environments. Additionally, the demonstrated fabrication process holds promise for creating large-diameter aberration-correcting meta-optics.…”

Dispersion-engineered metasurfaces reaching broadband 90% relative diffraction efficiency

“…Recent advances in high-efficiency metasurfaces have been realized with low-loss dielectrics such as HfO 2 , TiO 2 , amorphous silicon and PbTe in the ultraviolet, visible and infrared region 1 – 5 , respectively. Using these optically lossless materials improves efficiency at design wavelengths and has led to various metasurface components such as pulse-shapers 6 , 7 , ultrafast beam deflectors 8 – 10 , metalenses 2 , 3 , depth sensors 11 – 13 , full-Stoke polarization cameras 14 , 15 and virtual and augmented reality components 16 – 20 . The manufacturing of these metasurface components, instead of grinding, polishing and molding used in conventional optical components, is based on lithography, the same approach for chip manufacturing.…”