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Technologies

Atomic Layer Deposition coatings for complex substrates

Atomic layer deposition (ALD) is a promising method for depositing conformal thin films on complex structure substrates leveraging the self-limiting nature of surface reactions inherent in the ALD process. The application of ALD is especially important for manufacturing of optical coatings on complex structure substrates (small dimensions (1-3 mm and less), low-radius, multi-prism prisms, gratings, etc.) as well as temperature and environment sensitive substrates. During the past few years ALD was used to deposit coatings on substrates such as DKDP, KYW, KGW, synthetic diamond, YLF, CaF, GaSe, GaAs based solar cells, fiber optics and free-form multi-level micro-optics.

 

ODL ALD

Dense coatings with controlled dispersion for ultrashort pulses

Dispersive mirrors for ultrashort pulse compression require high precision deposition ensuring sub nanometer accuracy of deposited layers. Ion beam sputtering technology enables us to form dense layers and deposit homogenous multilayer coatings featuring negative or low GDD values.

Additionally, we have expertise to predict and optimize various other parameters including but not limited to: stress induced curvature, LIDT, light absorption.

Currently, possibilities to merge IBS deposition technology with GLAD deposited layers were tested in order to expand the application range even further.

 

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Periodically modulated coatings

Coatings deposition on periodically modulated surfaces enables the fabrication of 2D and 3D photonic crystals. Our advanced control of the layer growth on periodically modulated structures improves and provides new possibilities to manipulate optical characteristics of optics. Our current applications include but not limited to spatial filtering, the development of high-contrast 0 AOI polarizers and enhanced phase retardation.

 

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Sculptured coatings

GLAD (Glancing Angle Deposition) technology allows precise control over the angle between the vapor flux and the substrate surface. This control enables the creation of multilayer coatings with varied porosity and structural characteristics for each layer. In ODL, sculptural coatings are formed and investigated using different materials (SiO2, LaF3, Al2O3, etc.). In the laboratory, we focus on further investigating three main GLAD topics:

  • High-reflectance all-silica mirrors with super resistivity to laser radiation
  • Anti-reflective coatings for high-power lasers
  • Anisotropic coatings for zero-order waveplates and zero-angle polarizers

 

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Plasma ion assisted deposition of metal oxides

Plasma ion assisted deposition (PIAD) technology is very attractive, since it allows to form dense, envirozment-stable films and tweak other important optical, mechanical film properties by adjusting plasma parameters (ion energy, current density, selection of gas).

Current research activities are related:

Research on PIAD formed HfO2, SiO2 films for controlling coating optical properties, coating stress and improving LIDT.

 

Advanced substrate preparation for high power laser optics

Polished optical substrates usually have a so-called Beilby layer, which absorbs laser radiation. Therefore, potential of optical resistance of bare substrate or transparent optical coating is limited by occurring sub-surface damage within the Beilby layer. Research activities are targeted for investigating oxygen and argon plasma properties, other important factors, in order to effectively remove this subsurface layer without possible additional negative impact, as for example increased surface roughness, additional contamination, etc. Main activities are related to:

  • Research on plasma etching of fused silica and different laser crystals, such as YAG, MALO (Co dopped spinel), BSO.
  • Deposition and investigation of anti-reflective, polarizing coatings by different coating technologies on plasma etched substrates.

 

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Metal/dielectrics coatings

Optical components are typically fabricated by optical substrates coated with various dielectric layers. Nevertheless, the combination of dielectric with metallic (Au, Ag, Cu, Al, Cr etc.) layers lets to create optical coatings with unique properties. It is possible controllably deposit the metal film from the nanometre scale thickness.  Such metal-dielectric coatings might be used in the manufacture of broadband or wide-angle beam splitters, absorbers, solar cells, sensors, high-reflective mirrors and not only.

 

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Transparent conducting films

Transparent conducting films (TCFs) are thin films used as an important component in a number of electronic devices, including liquid-crystal displays, LEDs, OLEDs, touch screens and photovoltaics. Moreover, it might be used in laser schemes, smart windows and photonic applications.

 

Characterization of optical elements using laser radiation

With the rapid development in laser technology, the requirements for optical elements are increasing. They should not only have complex and precise spectral properties, but should also be of high laser radiation resistance. In 2016, an automated laser stand was created for testing such properties of optical coatings in the laboratory.

The main researches carried out are as follows:

  • Resistance of optical elements to laser radiation (according to the ISO-11254 standard and slightly modified using microfocusing tests). Influence of defects on optical resistance. Assessment of the quality of the coatings according to the morphology of the damage.
  • Evaluation of mirror reflection coefficients using CRD methodology for different angles of incidence and polarization.
  • Determination of the distribution of scattering of optical elements (“mapping”) at a fixed angle.

 

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