CS274107B1 - Method of aluminium and silicon oxides combined thin layers production in interference systems of layers for 2,7 till 3,5 micrometer wavelength range - Google Patents

Abstract

The solution concerns the field of optical interference layers and handles the problem of preparation of non-absorbing and mechanically resistant interference layers for the band of wave lengths between 2.7 and 3.5 micrometers by the method of vacuum vaporisation. The principle of the solution lies in forming thin aluminium layers (Al2O3) prepared by vacuum reactive vaporisation under the oxygen pressure between 1 x 10 <-2> to 2 x 10 <-2> Pa with the speed of layer growth between 0.5 and 1.5 nm/s per the base at the temperature between 200 and 300 degrees C in combination with silicon layers (Si) vaporised in high vacuum at the pressure under 2 x 10 <-3> with the speed of layer growth between 2 and 5 nm/s at the temperature between 200 and 300 degrees C. These systems of layers indicate low values of optical absorption in comparison with layers of commonly used titanic and silicon oxides (Ti02, Si02) in the introduced field of wave lengths and also good mechanical and chemical resistance.

Description

The invention uses a combination of vacuum vrgtev steamed alumina (Al ₂ O ₃₎ and silicon (Si) 'ge which has low optical absorption at wavelengths from 2.7 to 3', 5 microns, ¹ for the production of interference systems for the layers said wavelength range.

Laser devices operating at 3 nm wavelengths (eg YAGjEr based lasers) require the use of optical elements and interference layer systems with low optical loss, high resistance to intense optical radiation, and good mechanical and chemical-climatic resistance. Interference mirrors and other thin-film elements for use in the wavelength range of 2.7 to 3.5 μια and are made-usually from vacuum-vaporized systems of layers of metal fluorides, sulfides and selenides, possibly even some halides. The disadvantage of these layers is their low mechanical, chemical and climatic resistance. The layers of commonly used titanium, silicon and zirconium oxides (TiO 2, SiO 2, ZrO 2) prepared by reactive vacuum vapor deposition, having satisfactory mechanical properties and chemical resistance, exhibit optical absorption in the wavelength range of 2.7 to 3.5 µm. that disables their function. In order to prepare layers of these materials without undesirable absorption in this wavelength range, ion sputtering technology or other ionic technology must be used but are not readily available.

These drawbacks are largely eliminated in layer interference systems made using the combination of layers according to the invention, which consists of alternating vacuum-vaporized alumina (Al 2 O 3) and silicon (Si) layers.

It has been found and experimentally verified that aluminum oxide (Al ₂ 0 ₃ ) layers prepared by a vacuum reactive electron beam vapor deposition in cyanobium at a pressure of 1 x 10 ^-2 to 2 x 10 ² Pa at deposition rates of 0.5 to 1.5 nm / s to a substrate having a temperature of 200 to 300 ° C, exhibits negligible optical absorption in the wavelength range of 2.7 to 3.5 µm, unlike other oxide layers. Aluminum oxide layers (Al203) made under oxygen pressure of 1 x 10 to 2 x 10 ' ² Pa without taking due dilution are characterized by the same characteristics as vacuum-grown aluminum single crystals (Al20 ₃ ) tempered in the same environment as the vaporization process of aluminum inclusions (Al ₂ 0 _3), <moving the ultraviolet absorption edge of 190 to 250 nm while increasing the radiation resistance of 3 pm, regions of high energy density in the conventional laser beam. The aluminum layers (Al 2 O 8) thus produced can be used for the construction of interference layer systems as low refractive index gates. Oako material of the high refractive index layers can be used pure silicon (Si) vaporized again by electron beam under high vacuum at a pressure below 2 x 10 Pa at a rate of 2 to 5 nm / s again on a heated support. It has been found that the aluminum / silicon (AlgOg / Si) layer systems thus produced are suitable for the preparation of highly reflective semipermeable and other optical elements for laser optics operating at a wavelength of 3 µm and exhibit good mechanical and charcoal-climatic resistance.

The described film systems are also suitable for the preparation of mirrors, optical splitters, filters and other optical elements for wavelengths> 1, 2 µm and exhibit higher thermal and time spectral stability than the film systems of commonly used oxides.

Example:

For use in a 2.74 µm YAG: Er laser, resonator mirrors with p-99% reflectivity on optically polished BK 7 and Ephirium Eel Wool substrates and partially transmittance and about 70% reflectance on sapphire mats were made. Systems of layers of aluminum / silicon (AlgOg / Si) comprises seven or four layers of tloušfkéch 0 '46 pm alumina (Al ₂ 0 ₃₎ 0 * silicon produces 21p _m (Si) for a mirror with a reflectivity> -99%, respectively, 70%, wherein the layer system starts with a silicon (Si) layer on the substrate. The mirrors were verified in operation on a YAGiEr laser sample, where they achieved an output energy of 100 mO per pulse. For comparison: when the highly reflective mirror is replaced with a metal mirror with a reflecting layer of gold, the available output energy has decreased by 25%,

CS 274107 Bl

Claims (2)

OBJECT OF THE INVENTION Process for producing combined thin layers of alumina and silicon in interfering layer systems for the wavelength range 2.7-3.5 µm deposited on a substrate characterized in that it is formed on the one hand of alumina layers (Al_0_) prepared -2 - 2 by vacuum reactive vapor deposition at 1x10 to 2x10 Pa at a layer growth rate of 0.15 to 1.5 nra / s and a substrate temperature of 200 to 300 ° C, and from silicon (Si) layers prepared by vacuum vapor deposition at residual pressure gasses below 2x10 Pa at a layer growth rate of 2 to 5 nm / 9 and a substrate temperature of 200 to 300 ° C.