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Illumination of hafnium dioxide (HfO2) thin films with a nanosecond pulsed laser reaching peak intensities of 180 GW / cm2 has been shown to trigger a laterally expanding plasma wave prior to ablation that reaches speeds of up to 100 km / s. The phenomenon has recently been described as a defect-initiated laser-driven detonation (LDD) wave propagating in the electron–hole subspace, but the electron/hole effective masses that would be required for quantitative agreement were found to be at least 100 times heavier than band structure calculations predicted for HfO2. The results are re-examined in the context of a more general description of LDD that accounts for a change in the electron effective mass between the pre- and post-detonation states. Reasonable agreement between theory and experiment is found under the assumption that the electron’s effective mass decreases by a factor of 20 and approaches the free electron mass in the final state.

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An ion-beam sputtered film of hafnium oxide was irradiated with an intense nanosecond laser pulse above the ablation threshold. The transmitted laser power was measured as a function of time, with a resolution of a few hundred picoseconds. The spatial origin of the defect-triggered ablation was monitored for each event. A phenomenological model of a rapidly expanding, absorbing disk can explain the observed time dependent transmission and structure sizes of the affected material. The required expansion speeds, ranging from 1 to 100 km/s, and their observed dependence on the local laser intensity, are compatible with a laser-driven detonation wave as described by the Chapman–Jouget (CJ) theory. Because the energy deposited by the laser pulse is too low to explain detonation in a material with the density of hafnium oxide, we hypothesize that the detonation wave propagates in the electron–hole subspace. We modified the CJ theory to describe laser-driven detonation in an electron–hole plasma and to account for plasma expansion sideways to the laser beam.

Spatio-TEmporally REsolved Optical Laser-Induced Damage, or STEREO-LID, is a novel laser damage technique which measures the actual fluence (and intensity) at which damage occurs in a single pulse. This is accomplished by measuring the initiation time during the pulse and the initiation position within the beam profile. This technique has been demonstrated in the measurement of the defect distribution of single films and surfaces. In this paper, we demonstrate the technique to characterize laser-induced damage in high reflectors by single 8.3 ns pulses at 1064 nm. The high reflectors were quarter-wave stack of HfO2/SiO2 on a fused silica substrate. Applying STEREO-LID to high reflectors required a change in geometry as the technique previously used light transmitted through the optic. Instead, the initiation time is identified by a disruption of reflection and scattered light. The initiation position is determined by imaging the backscattered laser light. The STEREO-LID results are compared to the traditional 1-on-1 damage test to show that it is superior at detecting critical fluence limiting defects.

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The laser damage behavior of high quality coatings under nanosecond pulse illumination is controlled by statistically distributed defects, whose physical nature and defect mechanisms are still largely unknown. Defect densities are often retrieved by modeling the fluence dependence of the damage probability measured by traditional damage test (TDT) methods, based on ‘damage’ or ‘no damage’ observations. STEREO-LID (Spatio-TEmporally REsolved Optical LaserInduced Damage) allows the determination of the damage fluence (and intensity) in a single test by identifying the initiation of damage both temporally and spatially. The advantages of this test method over the TDT are discussed. In particular, its ability to retrieve detailed defect distribution functions is demonstrated by comparison of results from HfO2 films prepared by ion-assisted electron beam evaporation, ion-beam sputtering, and atomic layer deposition.

A technique for measuring the ablation and laser-induced damage threshold (LIDT) by identifying the temporal onset of damage and location of initiation within the beam profile is demonstrated. This new method, dubbed Spatio-TEmporally REsolved Optical Laser Induced Damage (STEREO LID), is compared to traditional damage tests and its advantages are exemplified.

We present a novel technique to characterize coating imperfections that limit the performance under pulsed laser irradiation. We also discuss the use of 1D photonic crystals based on dielectric metal oxides as nonlinear optical frequency converters.

We present a consistent model supported by experimental data of damage of dielectric films by femtosecond to nanosecond pulses. Special emphasis is given to the role of defects and transient processes in the material. New imaging and diagnostic techniques are discussed to characterize the film performance.

We show that the concentration of oxygen defects trapped in Sc2O3 films by ion beam sputtering can be controlled by modifying deposition conditions. These defects play a role in the optical and structural properties of the thin film metal-oxides.

Spatiotemporally resolved optical laser-induced damage is an experimental technique used to study nanosecond laser damage and initiation of ablation in dielectric metal-oxide films used for optical coatings. It measures the fluence (intensity) at the initiation of damage during a single laser pulse. The technique was applied to coatings of HfO2, Sc2O3, and Ta2O5, which were prepared by ion-beam sputtering, and HfO2 which was prepared by electron-beam evaporation. Using the data obtained, we were able to retrieve the defect density distributions of these films without a priori assumptions about their functional form.

We have investigated the role of native point defects in the laser damage behavior of amorphous thin films of Sc 2 O 3 deposited by ion beam sputtering. Through systematic characterization and detailed modeling we show that native defects influence the 1-on-1 laser induced damage threshold fluence of the Sc 2 O 3 . This effect, as shown by the model and confirmed by experiments, is pulse duration dependent.

A procedure is developed to retrieve defect densities of optical coatings and surfaces from spatiotemporally resolved optical-laser induced damage (STEREO-LID) measurements. In STEREO-LID, the temporal onset and location of nanosecond laser damage initiation is measured for each excitation event. The power of STEREO-LID relative to traditional damage tests resulting in damage probabilities is characterized with LID data from Monte Carlo simulations.

We show that the concentration of oxygen interstitials trapped in Sc2O3 films by ion beam sputtering from metal targets can be controlled by modifying deposition conditions. We have identified point defects in the form of oxygen interstitials that are present in Sc2O3 films, in significantly high concentrations, i.e., ∼10(18) cm(-3). These results show a correlation between the increase of oxygen interstitials and the increase in stress and optical absorption in the films. Sc2O3 films with the lowest stress and optical absorption loss at 1 μm wavelength were obtained when using a low oxygen partial pressure and low beam voltage.