Nonlinear absorptance of single-layer HfO coatings: investigating the impact of thermal and laser annealing.

In this study we explore optical absorptance of single-layer hafnia dielectric coatings deposited on fused silica by ion beam sputtering technique. We investigate both linear and nonlinear absorptance by varying the laser intensity of 10 ps pulses at a 1 MHz repetition rate across wavelengths of 1064 nm, 532 nm, and 355 nm. Significant differences were observed between the as-deposited and thermally treated coatings.

Broadband chirped mirrors with a porous top layer for smooth group delay dispersion.

The effectiveness of ultrashort pulse compression depends on the coatings group delay dispersion (GDD) characteristics in chirped mirror (CM)-based optical systems. Current porous-layer-based CMs with low GDD oscillations are limited to less than half optical octave spectral bandwidth and the stability of their spectral parameters is still unknown. In order to address these limitations, a broadband CM (covering 400 nm bandwidth) with a porous top layer was deposited and spectral parameters were measured at different environmental conditions.

Contrasted fatigue behavior of laser-induced damage mechanisms in single layer ZrO optical coating.

The decrease of laser-induced damage threshold (LIDT) when exposed with high number of laser pulses is a well-known phenomenon in dielectrics. In the femtosecond regime this fatigue is usually attributed to the incubation of laser-induced lattice defects. In this work, a computational model is used to combine the data from time-resolved digital holographic microscopy measurements together with results of S-on-1 laser-induced damage threshold test in order to investigate fatigue of ZrO single layer coating.

Enhancement of laser-induced damage threshold in chirped mirrors by electric field reallocation.

In this paper, the relation between the laser-induced damage threshold (LIDT) and the electric field intensity (EFI) distribution inside a CM is investigated experimentally. We show that it is possible to increase the LIDT values by slightly modifying the electric field of a standing wave distribution without loss of spectral and dispersion performance. Suggested CM design improvement could increase reliability and LIDT performance of both CM elements and high-power systems they are used in.

Flat focusing mirror.

The control of spatial propagation properties of narrow light beams such as divergence, focusing or imaging are main objectives in optics and photonics. In this letter, we propose and demonstrate experimentally a flat focusing mirror, based on an especially designed dielectric structure without any optical axis. More generally, it also enables imaging any light pattern in reflection.