Rectangular multilayer dielectric gratings with broadband high diffraction efficiency and enhanced laser damage resistance

Abstract

Broadband multilayer dielectric gratings (MDGs) with rectangular HfO2 grating profile were realized for the first time using a novel fabrication process that combines laser interference lithography, nanoimprint, atomic layer deposition and reactive ion-beam etching. The laser-induced damage initiating at the grating ridge was mitigated for two reasons. First, the rectangular grating profile exhibits the minimum electric-field intensity (EFI) enhancement inside the grating pillar compared to other trapezoidal profiles. Second, our etching process did not create nano-absorbing defects at the edge of the HfO2 grating where the peak EFI locates, which is unavoidable in traditional fabrication process. The fabricated MDGs showed a high laser induced damage threshold of 0.59J/cm2 for a Ti-sapphire laser with pulse width of 40 fs and an excellent broadband diffraction spectrum with 95% efficiency over 150 nm in TE polarization.

The Development Progress of Surface Structure Diffraction Gratings: From Manufacturing Technology to Spectroscopic Applications

“…The PDMS mold was imprinted onto the resist (PMMA), spin-coated on the multilayer dielectric film mirror by UV nanoimprint lithography, and the resist grating structure opposite to the target HfO 2 grating structure was obtained. A rectangular diffraction grating with a diffraction efficiency of 95% (from 714 to 865 nm) and a damage resistance threshold of 0.59 J/cm 2 (40 fs) was fabricated [80].…”

Phase Mask Pinholes as Spatial Filters for Laser Interference Lithography

“…GWS are known to be a powerful solution to control key properties of light and in particular for tailoring the polarization and for realizing spectral and spatial beam shaping in high power laser systems. [14,15] The uniformity of the two key properties of GWS, period and linewidth (LW), is essential to achieve high optical efficiency. [16] Here, we come back to LIL because it is well suited for GWS fabrication due to its high period precision, if the dimensional variations caused by the Gaussian beam profile can be countered, especially for large-area GWSs.…”

Influence of the multilayer dielectric design on the laser damage resistance of pulse-compression gratings

“…A lot of studies have been carried out to improve the LIDT of MLD gratings by optimizing the design, manufacturing, and cleaning processes. [4][5][6][7] The efforts were mainly devoted to the etching profile. Néauport et al demonstrated the significant impact of the etching profile on the electric field intensity (EFI) and the laser resistance.…”