Non-polarizing beam splitter and its forming method

Technical field

BACKGROUND OF THE INVENTION The present invention relates to optical means for reflecting light and relates to non-polarizing light beam dividers.

State of the art

Non-polarizing fiber-optic dividers use non-polarizing multilayer coatings consisting of thin layers of material varying in thickness from a fraction of a nanometer (e.g., one atomic layer) to several or several tens of micrometers. Multilayer coatings or single layers thereof are widely used in the high technology field. Controlled synthesis of materials to create such coatings (a process referred to as deposition) is a fundamental step in many applications. During the 20th century, advances in vapor deposition techniques have led to many technological breakthroughs in various fields such as magnetic media, electronic semiconductor equipment, light emitting diodes, optical coatings (such as high reflection coatings), and energy generation (e.g. , such as thin-film solar cells) and storage (e.g., thin-film coating batteries). These are just a few examples of applications that are growing in number each year.

In the manufacture of optical components, the functionalization of surfaces using thin layers of various materials to alter the physical or optical properties of a component has become widespread. Typical examples of such coatings could be the application of an optically brightening layer to reduce the reflectivity. Various filters, mirrors (such as semi-permeable mirrors), polarizers or non-polar coatings are also examples of the use of these coatings. All of the above-mentioned optical components use thin-film coatings to control the spectral, polarization, angular, spatial or other characteristics of the light.

In the photonics industry, several key technologies used in thin-film coatings are prevalent. The simplest is physical vapor deposition, in which the material is evaporated by direct heating in high-resistivity crucibles. In a vacuum environment, the evaporated particles are deposited on opposite optical components, which form a thin-film optical coating. Slightly more sophisticated technologies include heating the target material with accelerated electron beam or ion beam bombardment. Alternatively, the resulting coating may be further compacted with accelerated bulk ions or neutral particle fibers directed at it to provide a denser and more mechanically resistant coating.

U.S. Patent No. 654178 B1, issued November 23, 2003, describes a non-polarizing light beam divider comprising two glass prisms, one of which is formed with a non-polarizing coating, and then the prisms are glued together. The manufacturing method described in this patent allows the making of a non-polarizing fiber divider using four different materials. These materials are used to create different groups of layers. These groups of layers are used to form a non-polarizing divider coating. The disadvantage of the known divider is that the coating is made up of many layers, which results in a more complex search and matching of materials, and thus a more complicated design and manufacture of the divider.

U.S. Patent No. 5,887,898, issued September 15, 1998, describes a method for obtaining a non-polarizing fiber divider using dual refractive index crystals. The use of polymers to obtain a dual refractive index material as an alternative to crystals is also disclosed in the disclosure. The non-polarizing beam splitter produced in this way can be used in a wavelength range of 300nm to 700nm depending on the angle. The divider has a wide adjustment angle from 30 ° to 60 °. The drawback of the known divider is the narrow range of waves in which the divider can operate.

U.S. Patent No. 7652823 B2, published January 23, 2010, describes a non-polarizing fiber splitter comprising a first rectangular prism, one or more layers of a dielectric substrate formed on a sloping plane of a first rectangular prism, formed on said one or more outer dielectric substrate layers. a layer of gold having a thickness of 13 to 35 nm on which one or more protective dielectric layers are formed, and the second rectangular prism is glued to the outer protective dielectric layer. The fiber divider operates in the 640-820 nm range. To protect the gold plating more reliably against mechanical stress, an additional 7 layer overlay of transparent dielectric layers is formed. The difference of the formed fiber divider between S and P for polarization for both reflectivity and transmittance does not differ by more than 10%.

The disadvantage of the known divider is that expensive metal gold is used to form the metal layer, and several layers are required to protect this layer, which makes the production of this divider complicated and expensive.

U.S. Patent Application No. US2012 / 0212830 A1, published August 23, 2012, describes a non-polarizing fiber divider comprising at least one substrate on which a partially reflective coating consisting of several layers is formed. The sequence of said layers comprises at least one metal layer, at least two first reflective layers, one with a high reflection coefficient and another with a medium reflection coefficient, and at least two second reflective layers, one with a low reflection coefficient and the other with average reflectivity. At least one first reflective layer and at least one second reflective layer are fluoride and oxide layers, and the metal layer is Aluminum, 1-30nm thick. The manufactured non-polarizing divider is used in the wavelength range 175-1300nm.

The drawback of the known divider is the narrow range of waves in which the divider can operate. In addition, the coating is made up of many layers, which makes it more difficult to find and match materials, while also making the divider design and manufacture more complicated and expensive. Aluminum used as a metal layer is aluminum that degrades rapidly, which reduces the life of the divider and reduces its reliability.

Resolving a technical issue

It is an object of the present invention to extend the field of application of the light beam divider by extending the wavelength range and the range of tuning angles within which the proposed fiber divider can operate. It also simplifies the design and manufacture of the divider, increasing its service life and reliability.

The essence of the solution of the invention

SUMMARY OF THE INVENTION According to the present invention, a non-polarizing light beam divider comprising first and second substrates between and formed a partially reflective non-polarized layered coating having at least one dielectric backing, at least one metal layer and at least one protective layer dielectric layer, the metal layer is copper layer

The non-polarizing coating consists of three layers, wherein a dielectric layer is formed on the first substrate by a copper layer on a dielectric substrate and a protective layer on the copper layer by a second substrate.

The thickness of the copper layer is in the range 1-35nm.

The base of the dielectric layer and the dielectric layer may be of metal oxide or metal nitride or metal fluoride.

The dielectric layers may be of hafnium oxide or aluminum oxide or titanium oxide or scandium oxide or niobium oxide or magnesium fluoride or lanthanum fluoride or aluminum nitride or any other dielectric material or mixtures thereof.

The base of the dielectric layer and the protective layer of the dielectric are in the same or different thicknesses from 1nm to 1000nm.

The divider is constructed by selecting the material and thickness of the layers (3), (4), (5) of said non-polarizing coating so that the reflection or transmission of said coating is in the range of 5% to 95% of a wavelength selected from the wavelength range 500 up to 3000 nm, the difference between S and P polarization of the reflected and transmitted light beams is less than 5% for at least one selected wavelength within the said wavelength range and the loss of the formed coating does not exceed 10%.

The second substrate is glued to the protective dielectric layer.

The first tray and the second tray are in the form of a rectangular prism and a layered non-polarizing coating is formed between and connected to the sloping planes of the prisms to form a cube-shaped outer divider.

The lateral surfaces of the prism are opaque to at least one selected wavelength from said wavelength range.

The first and second trays are made of a transparent material selected from materials such as quartz glass and / or CaF2 and / or Mg.F2.

A method of forming a non-polarizing fiber divider by forming a layered non-polarizing coating comprising the steps of: providing a first substrate; , joining the outer protective layer of the dielectric to the second substrate, said metal layer being copper.

Said non-polarizing layers are sequentially formed in a vacuum chamber by the action of a target layer material so that the target material generates particles which are deposited by forming a thin layer on the first substrate or on the respective pre-formed coating layer, respectively.

The forming layer material generates particles by evaporation by heating the target material in a resistive evaporator.

The forming layer material generates particles by evaporation by bombarding the target material with electrons.

The particles of the forming layer are generated by magnetron sputtering.

Utility of the invention

The present invention extends the field of application of the light beam divider since the beam divider according to the present invention can operate in a wider wavelength range of 500 to 3000 nm and in a larger tuning angle range of 35 ° to 55 °. In the divider, the difference between the polarizations S and P of the reflected and transmitted light beam is less than 5% for at least one selected wavelength from said wavelength range.

In addition, the metal layer used in the divider coating is copper, which degrades more slowly and is not expensive. The fiber divider coating can consist of only three layers of only two different materials, which facilitates the search and matching of materials, thereby simplifying and understanding the construction and production of the fiber divider, increasing its service life and reliability.

According to the present invention, the non-polarizing spectrum divider divides the light beam into two parts (reflected and past). The polarization of s and p of the reflected and past beams remains constant, or the difference between these polarizations remains less than 5%. The optical properties of the formed coating depend on the thickness of the metallic and dielectric layers being formed and the materials selected, resulting in a coating reflection or transmission of between 5% and 95% for at least one selected wavelength range within the range 500-3000 nm. The loss of formation and absorption due to the formed coating shall not exceed 10%. For the purpose of the present invention, it is sufficient to use two materials, metal brass and dielectric.

The invention is explained in more detail in the drawings, wherein

Fig. 1 is a schematic diagram of a non-polarizing light beam divider.

Fig. 2 is a schematic diagram of a thin-film coating equipment.

Description of Embodiment of the Invention

The proposed non-polarizing light splitter comprises a first tray 1 and a second tray 2. Trays 1 and 2 may optionally be flat or other configurations. The pallets depicted in Fig. 1 are of transparent material in the form of rectangular prisms 1 and 2. Between the sloping planes 1 and 2 of the prisms, a coating is formed which consists of layers (3, 4, 5). Layer 4 is a copper layer and layers 3, 5 are dielectric layers of metal oxide or metal nitride or metal fluoride. On the sloping plane of the transparent prism 1 is formed a base dielectric layer 3 on which a copper layer 4 is formed, and on the copper layer a protective dielectric layer 5 is formed which is glued (6) to the sloping plane of the second transparent prism (2). form. The proposed divisor is designed to efficiently divide the incident beam of light into a given transmittance and reflectance ratio, for at least one selected wavelength range and angle, without changing the S and P polarization ratios. Preferably, the formed divider deflects the reflected portion of the beam by 90 degrees to the incident light. The materials for forming the coating layers 3, 4, 5 can be evaporated from two different evaporation sources using two different materials (pure metal copper (4) and a dielectric such as metal oxide, nitride or fluoride (3,5).

The most suitable method of forming the proposed divider comprises the following steps: the vacuum chamber is provided with at least one tray 1 on which the coating layers (3, 4, 5) are formed. Trays 1 and 2 are not limited to their shape, quantity or material. FIG. Trays 1 and 2 shown in Figure 1 are selected from transparent materials such as quartz glass and / or CaF2 and / or Mg.F2. The pallets can be mounted on a dedicated holder 7 which can be adapted to fasten and rotate many pallets. The substrate 1, mounted in the holder 7, rotates along the vertical axis 8 with the holder 7 during the formation of the coating. This rotation of the substrate ensures a more uniform coating of the coating at all points on the surface of the substrate 1 and a more uniform distribution.

In another embodiment, a plurality of pallets 1 are mounted in a pallet holder 7 such that a planetary movement trajectory is realized. When the pallet holder rotates about its axis 8, the individual pallets or pallet clusters rotate about a local axis (not shown).

Various industrial coating technologies can be used to implement the present invention. In its simplest embodiment, in a vacuum chamber, target material 9 is evaporated by heating it in a crucible.

According to the present invention, copper having a thickness of 1-35 nm is used to form layer 4 depending on the selected cell characteristics. The range of materials for layers 3 and 5 is quite wide: hafnium oxide, alumina, titanium oxide aluminum, scandium oxide, niobium oxide, magnesium fluoride or lanthanum fluoride, or any other dielectric material, or mixtures thereof, can be used to generate the vapor stream 10. . Vapors from these substances are produced at near melting points and under vacuum conditions.

In another embodiment, the target material 9 is atomized by ion bombardment bombardment. By bombarding the target with the ion beam, the atoms of the material are shot from it. A steady stream of ions generates a steady stream of particles of target material 10 in a well-defined predominant direction.

In another embodiment, the target material 9 is vaporized by directing it towards the accelerated electron beam. By heating the target material with electron flow and creating vacuum conditions, the atoms of the material separate from the target surface and evaporate in all directions, similar to thermal evaporation. A steady stream of electrons generates a steady stream of target material vapor 10.

In another embodiment, the target material 9 is precipitated by magnetron sputtering. In a vacuum chamber, a strong magnetic field is generated to ionize the gas, the ions exposed to the magnetic field, to fly the target material and knock out the atoms of the material. This generates a steady stream of target material particles 10.

Another important aspect of the invention is the continuous monitoring of the forming coating. This process uses a physical monitoring mechanism and software to calculate the physical properties of the coating (hereinafter control device). Said physical mechanism may be witnessing a white light beam in reflection or transmission mode. In other embodiments, a narrow beam light source such as a luminaire or a laser may be used. In yet another embodiment, the coating thickness can be controlled by quartz microbalance scales. A combination of monitoring techniques may be used for any coating evaporation process.