acousto-optic modulator

Abstract

An acousto-optic modulator (10) comprising a piezoelectric transducer (20) having a first electrode (21), a second electrode (22) and a dielectric material (23) disposed between and in contact with the electrodes (21, 22); and an acousto-optic element (30) comprising at least two other dielectric materials (31, 32) having mutually different refractive indices, wherein the piezoelectric transducer (20) and the acousto-optic element (30) are laminated together, and wherein at least one of the other dielectric materials (31, 32) of the acousto-optic element (30) is a dielectric fabric having a bi-periodic structure.

Description

Technical Field

[0001] The present invention relates to an acousto-optic modulator, an arrangement of acousto-optic modulators and electrodes, an apparatus for processing a medium, and the use of said acousto-optic modulator and said apparatus for shortening the duration of light pulses and / or increasing the energy of photons, for processing a medium, for the synthesis of organic molecules, for the production of hydrogen from water and / or hydrocarbons, or any combination thereof, according to the preamble of the independent claims. Background Technology

[0002] Various acousto-optic modulators are known in the prior art, such as those disclosed in US 2007 / 0171513 A1, which includes a monocrystalline silicon acousto-optic intermodulator and at least one transducer attached to the monocrystalline silicon for emitting sound waves. However, such acousto-optic modulators generally suffer from drawbacks, namely that their production requires structures patterned with submicron precision, such as monocrystalline silicon, which are typically quite expensive and not readily available in large sizes and / or diverse shapes. The brittleness or rigidity of the crystal structure also makes these periodic structures difficult to adapt to uneven or shaped substrates, even if this is not impossible.

[0003] The use of electromagnetic radiation, particularly ultraviolet (UV) light, to purify and treat air in a space is also known in the prior art. For example, systems based on this principle for purifying and removing contaminants from fluids are known from EP 1660211 B1. Because the UV bulbs used in such devices have a limited lifespan, they may need to be replaced frequently depending on the application intensity and environmental conditions, which means a shortened lifespan and additional workload for the user.

[0004] Typically, the medium to be treated can be a gas, liquid, or gas / liquid mixture that undergoes plasma generation. The plasma is delivered into a processing chamber to prolong the duration of interaction between the plasma and the medium. However, the processing duration and / or intensity in the apparatus, particularly in the processing chamber, may be insufficient to achieve the desired processing results. Summary of the Invention

[0005] Therefore, one object of the present invention is to overcome these and other disadvantages of the prior art, and in particular to provide an acousto-optic modulator, an arrangement of acousto-optic modulators and electrodes, and a device for processing media, which can perform energy-saving and efficient processing, and is inexpensive and can be made into various shapes.

[0006] In the context of this specification, the term gaseous medium refers to a gas or gas mixture that may contain liquids and / or solids. Similarly, the term liquid medium refers to a liquid or liquid mixture that may contain gaseous and / or solid substances.

[0007] Although the invention is not limited thereto, the term processing includes the decomposition, synthesis, inactivation or division of molecules entrained in a processing medium, including biological structures such as proteins, pollen, fungal spores, bacteria, viruses and / or other microorganisms.

[0008] Furthermore, within the meaning of this invention, the term plasma is understood to refer to a gas and / or vapor that dissociates into its components under the influence of an electric field. Plasma includes photons, ions, free electrons, free radicals, and neutral particles, particularly excited neutral particles.

[0009] According to the present invention, an acousto-optic modulator includes a piezoelectric transducer having a first electrode, a second electrode, and a dielectric material disposed between and in contact with the electrodes. To ensure contact between the dielectric material and the electrodes, the piezoelectric transducer may optionally include two contact elements configured to ensure contact between the first dielectric material and the electrodes. The piezoelectric transducer also includes an acousto-optic medium having at least two other dielectric materials having different refractive indices. The piezoelectric transducer and the acousto-optic medium are laminated together. The acousto-optic medium includes at least one dielectric fabric having a dual-periodic structure.

[0010] Surprisingly, it has now been discovered that crystals in optical modulation can be replaced by fabrics with regular structures, specifically knitted fabrics of glass fibers or any other material with a high dielectric constant. This allows for the realization of large acousto-optic structures measuring tens of square meters, if desired or required. The flexibility of the fabric also enables the creation of complex acousto-optic modulator shapes. Compared to known conventional structures whose size is limited to a few square centimeters, material and manufacturing costs can be significantly reduced.

[0011] Piezoelectric transducers are known in the prior art and constitute an electroacoustic transducer that converts electrical charges generated by certain forms of solid materials into energy. It should be understood that piezoelectric layers, for example, can generate sound waves.

[0012] Acousto-optic modulators utilize the acousto-optic effect to diffract sound waves and change the frequency of light. Laser pulses force piezoelectric cells to vibrate, generating sound waves within the glass. These can be imagined as expanding and compressing planes, periodically shifting and changing the refractive index. The incident light is scattered (Brillouin scattering) beyond the periodic modulation of the resulting refractive index, resulting in interference, similar to the interference produced in Bragg diffraction. This interaction can be considered a four-wave mixture of phonons and photons.

[0013] To avoid being bound by theory, it is currently assumed that the sequence of physical phenomena involved in subjecting the acousto-optic modulator disclosed herein to simultaneous electrostatic field and pulsed electromagnetic radiation can be qualitatively described as follows: 1) The semiconductor, i.e., the acousto-optic element, absorbs the laser pulse to generate photoexcited free carriers; 2) These unbalanced electrons and holes diffuse in a pre-existing electrostatic field; 3) Spatial separation of charges generates a dynamic electric field between the electron clouds of electrons and holes; 4) This dynamic field induces mechanical confinement in the piezoelectric transducer through the piezoelectric effect, which is also the source of the sound waves. The main difference between the piezoelectric material used in this paper and conventional piezoelectric transducers is that the electric field applied to the material to generate sound waves is optically triggered, rather than electrically triggered, which allows for a significant extension of the operating frequency of the device described herein, reaching frequencies above GHz.

[0014] In the context of this specification, the term biperiodicity refers to the structure of a regular fabric, which can be defined as a unit that repeats periodically in two directions of the fabric (Grishanov et al., J. Knot Theory and its Ramifications, 18 (2009), 1597-1622). Knitted and woven fabric structures are examples of biperiodic structures in a thickened plane made of interlaced multiply yarns.

[0015] In a preferred embodiment, the acousto-optic modulator is part of a device for processing a medium, preferably air.

[0016] In a preferred embodiment, the acousto-optic modulator disclosed herein includes a piezoelectric transducer and an acousto-optic element. The piezoelectric transducer includes a first electrode, a second electrode, and a dielectric material disposed between and in contact with the electrodes. Optionally, the piezoelectric transducer further includes two contact elements configured to ensure contact between the first dielectric material and the electrodes. The acousto-optic modulator includes two other dielectric materials having different refractive indices. The piezoelectric transducer and the acousto-optic element are laminated together. One of the other dielectric materials of the acousto-optic element is a dielectric fabric with a dual-periodic structure.

[0017] Compared to the aforementioned acousto-optic modulators, this acousto-optic modulator, made of only two different dielectric materials (one of which is a fabric with a dual-periodic structure), is easier and cheaper to manufacture.

[0018] The electrodes of the acousto-optic modulator disclosed herein are used to apply a voltage to a dielectric material. Without being bound by theory, it is currently understood that the excitation of photons on the electrode surface can enhance the scattering of said photons through a mechanism called surface-enhanced Raman scattering (SERS). This can also increase the diversity of photons present in the processing chamber, as described in more detail below.

[0019] In a preferred embodiment of the acousto-optic modulator disclosed herein, the first and / or second electrode materials are selected from metals, activated carbon, graphene, and ionomers.

[0020] Such electrodes are readily available and can be manufactured into various shapes. The compositions of the first and second electrode materials can also differ from each other.

[0021] Preferably, the first and / or second electrodes are aluminum.

[0022] Electrodes made of aluminum have the advantages of being relatively inexpensive and having good ductility. Furthermore, aluminum foil and suitable aluminum sheets are generally readily available. In addition, aluminum on the electret enhances Raman scattering and luminescence.

[0023] Similarly, not wanting to be bound by theory, this phenomenon, which can reach 15 times, can be explained by the enhancement of the local electric field applied to molecules and atoms. This enhancement originates from the coupling of laser light with electron density waves, which appear near the surface of certain metals, preferably having submicron or even nanometer dimensions. These electron density waves are caused by the free electrons of the metal. The new particles formed through this coupling are called surface plasmon polaritons. If the resonant frequencies of these surface plasmon polaritons are in the visible light range of the electromagnetic spectrum, they can couple to amplify the local electric field. Therefore, the surface-enhanced Raman scattering (SERS) effect is primarily a result of the enhanced electromagnetic field generated by the metal surface. When the wavelength of the incident light is close to the plasmon wavelength of the metal, the conduction electrons on the metal surface are excited to delocalized electronic states corresponding to the surface plasmon resonance. Molecules adsorbed on or near the surface experience a particularly strong electromagnetic field. In this case, the normal vibrational modes of the surface increase most strongly.

[0024] Preferably, the thickness of the aluminum foil is between 4 and 100 μm, more preferably between 4 and 20 μm.

[0025] By selecting the indicated aluminum foil thickness, transducer vibrations generated by the oscillating radio frequency drive signal applied to the electrodes can be effectively transmitted to the adjacent acousto-optic medium. In particular, according to the invention, it is conceivable to use household aluminum foil with a typical thickness between 10 and 15 μm.

[0026] In the context of this specification, the term thickness refers to the average thickness of the foil material.

[0027] The acousto-optic modulator disclosed herein is characterized by a thermal electret, which is prepared by placing a dielectric material between two electrodes and maintaining the dielectric material or a mixture of dielectric materials at a suitable temperature for an extended period of time under an applied hinged DC potential, and then cooling the article to room temperature while maintaining the DC potential.

[0028] In the context of this specification, the term electret is understood to be a layer of dielectric material having (quasi)permanent charge, thus generating a (quasi)permanent electric field.

[0029] In a preferred embodiment of the acousto-optic modulator disclosed herein, the dielectric material of the piezoelectric transducer comprises at least one natural wax selected from the group consisting of: palm wax, rosin, sugarcane wax, glyceryl rosin, lanolin, shellac wax, tallow, lignite wax, ceresin, whale wax, beeswax, crown palm wax, Japanese wax, bayberry wax, candelilla wax, Chinese wax, Chinese insect wax, and combinations thereof.

[0030] The advantage of the listed dielectric materials is that, as natural products, they are particularly environmentally friendly. However, it is of course conceivable, and according to the present invention, that the dielectric materials are composed of synthetic polymers, such as polyvinylidene fluoride (PVDF) resin, polyvinyl chloride (PVC) resin, polycarbonate (PC), polyester, acrylic resin, polyethylene (PE), polytetrafluoroethylene (PTFE), polypropylene (PP), polystyrene (PS), or copolymers and / or mixtures thereof.

[0031] Preferably, the dielectric material is selected from the group consisting of palm wax, rosin, beeswax, and combinations thereof.

[0032] Electrets made from these materials can maintain their polarization state for a long time and have excellent processability, toughness and flexibility.

[0033] In a preferred embodiment of the acousto-optic modulator disclosed herein, the dielectric material of the piezoelectric transducer is selected from the group consisting of ZnO, LiNb3, LiTaO3, SiO2, quartz, TiO2, Si, SiN, AlN, GaN, and SrTiO3.

[0034] In a preferred embodiment of the acousto-optic modulator disclosed herein, at least one contact element is a dielectric fabric.

[0035] The advantage of using fabric as a contact element is that, due to its flexibility and tensile strength, the fabric can compensate particularly well for the shrinkage that occurs when the dielectric material cools, thereby ensuring extensive contact between the individual electrodes and the dielectric material between them.

[0036] Preferably, both contact elements are dielectric fabrics. This allows for optimal connection between the dielectric material and the two electrodes sandwiching the dielectric material in between.

[0037] Preferably, the dielectric fabric used as the contact element comprises fiberglass knitted fabric. The advantage of fiberglass knitted fabric is that it is available in a variety of sizes and patterns on the market, allowing selection based on specific application requirements.

[0038] It has been shown that photonic crystals made of glass and silicon nitride can amplify fluorescence or luminescence by tens of times.

[0039] In a preferred embodiment, the acousto-optic modulator disclosed herein comprises a glass fiber knitted fabric impregnated with silicone resin.

[0040] Preferably, the silicone resin used to impregnate the glass fiber knitted fabric is an optical silicone resin. Optical silicone resins offer advantages such as high thermal stability, optical transparency, UV resistance, low shrinkage, and good molding properties, which facilitate the production of acousto-optic elements or modulators with complex shapes.

[0041] Not wanting to be bound by theory, by filling the spaces between the meshes of glass fiber knitted fabric with silicone resin, a structure in which the chemical composition varies with position was obtained, similar to the quantum well heterostructure used in the semiconductor industry.

[0042] Periodic glass fiber structures impregnated with silicone resin can also be considered photonic crystals. A photonic crystal is a periodic dielectric structure that blocks the propagation of photons of specific wavelengths. Similar to the electronic bandgap in semiconductors, photonic crystals have a photonic bandgap, which is a periodic variation in the dielectric constant, possibly caused by, for example, the presence of periodically spaced holes in the material. Thus, the photonic bandgap blocks the propagation of photons of specific energies. More precisely, a two-dimensional photonic bandgap blocks light within a specific frequency range from propagating in all directions along a plane. Instead, it guides the emitted light to the outside of the photonic crystal, thereby improving extraction efficiency.

[0043] To improve control over the emission direction, photonic crystals can be placed on certain types of mirrors, called Bragg reflectors. These mirrors then reflect the light emitted by the photoelectric material back to the outside.

[0044] In a preferred embodiment, the silicone resin used to fill the voids in the glass fiber knitted fabric comprises at least one type of Raman scattering crystal, preferably selected from the group consisting of diamond, corundum and / or quartz.

[0045] To avoid being bound by theory, it is currently assumed that electromagnetic radiation, i.e., photons, is more effectively scattered by these scattering particles, thereby increasing the processing effect caused by said electromagnetic radiation. In particular, Raman scattering, i.e., inelastic scattering of photons on crystals, supports an amplification of the number of photons and leads to an increase in the energy, i.e., frequency, of at least some of the scattered photons. The use of specified Raman scattering crystals is particularly preferred because these materials are readily available and relatively inexpensive.

[0046] In particular, regarding diamond, it is known that primary and secondary electron-hole pairs in diamond can be excited by photons (Gaudin et al., Appl Phys B 78 (2004), 1001-1004). While the invention is not limited thereto, it is understood that primary and secondary electron-hole pairs are excited in a diamond coating and then recombine by emitting two photons, thereby amplifying the number of photons incident on the acousto-optic element described herein.

[0047] As a substitute for natural diamond, zirconium oxide and / or other synthetic diamonds can be used. Preferably, a diamond coating with nitrogen dopant is used.

[0048] It is known in the art to generate so-called charged nitrogen-vacancy color centers using nitrogen-doped diamond, which can be excited by visible light and subsequently produce luminescence (Han et al., Nano Letters 9 (2009), 3323-3329). Although the present invention is not limited thereto, it is currently understood that this leads to more efficient dispersion of photons in plasma.

[0049] Preferably, the Raman scattering crystal is present in the silicone resin at a content of 0.1% to 2% of the weight of the silicone resin. Alternatively, the size of the Raman scattering crystal is between 4 and 1000 nm, preferably between 8 and 170 nm.

[0050] Compositions and particles with the above specifications allow for the production of particularly effective acousto-optic modulators.

[0051] A mirror can be used as an active optical element to focus an ultrashort light pulse onto a target. If the light has a sufficiently high intensity, it will be strongly ionized by a strong electromagnetic field during the extremely short time of the pulse's rising edge.

[0052] In a preferred embodiment of the acousto-optic modulator disclosed herein, the surface of the acousto-optic medium is configured to form SiO2 and / or SiN. x Plasma mirrors are generated by the action of plasma containing oxygen and / or nitrogen on a silicone resin layer (i.e., a silicone resin layer defining the interface between the acousto-optic medium and the plasma) at the surface.

[0053] In particular, silicon dioxide and silicon nitride (Si3N4) are well-established materials for photonic devices, exhibiting a wide transparency window from visible to mid-infrared light. These materials possess the qualities required for fabricating plasma-effect mirrors. They are widely used in optics and microelectronics and are renowned for their excellent electrical, mechanical, and thermal properties. Both silicon dioxide and nitrides are produced via chemical vapor deposition in a microwave plasma ECR reactor. This method is one of the low-temperature deposition techniques that can produce high-quality dielectric layers without damaging the substrate.

[0054] During the operation of the acousto-optic modulator disclosed herein, the silicone surface of the acousto-optic element is continuously exposed to oscillating plasma, which will be described in more detail later. This oxygen- and nitrogen-rich plasma can continuously reassemble thin surface layers of silicon dioxide (SiO2) and silicon nitride (Si3N4), which constitute the solid support of the plasma mirror, similar to an autogenous or self-healing effect.

[0055] The ability to form a plasma mirror at the interface between the acousto-optic medium and the overlying volume offers the advantage of stronger reflection of incident photons. Furthermore, the electromagnetic radiation pulse incident on the plasma mirror can be focused onto another plasma mirror, this time much stronger, and thus of even higher intensity, up to a relativistic interaction state, resulting in enhanced processing of the medium. It is also conceivable that this other plasma mirror is actually part of the same element as the first plasma mirror, for example in the case of a ring acousto-optic modulator, which will be explained in more detail below. In the relativistic interaction state, the light field causes oscillatory motion on the surface of the plasma mirror, resulting in periodic time distortion of the reflected wave via the Doppler effect. Due to this periodic distortion, the spectrum of the reflected light consists of a large number of higher harmonics of the incident laser frequency in addition to that frequency. This process, called the relativistic oscillating mirror process, allows for sufficiently high harmonic orders to produce ultrashort pulses.

[0056] The combination processes that occur in the heterostructures disclosed herein all contribute to the emergence of single photons, specifically optical pumping in diamond nanoparticles and luminescence in optical silicone resins.

[0057] In a preferred embodiment of the acousto-optic modulator disclosed herein, the total thickness of the laminate consisting of the piezoelectric transducer and the acousto-optic element is between 4 and 80 mm, preferably between 20 and 40 mm.

[0058] This objective is further achieved by an arrangement of at least one acousto-optic modulator and at least one electrode according to the present disclosure. A space is formed between the surface of the acousto-optic modulator and the electrode, in which a dielectric can be introduced. The electrode comprises at least a partial coating, preferably a complete coating, having a Raman scattering crystal, particularly diamond.

[0059] Preferably, the arrangement includes a ring acousto-optic modulator as described herein and at least one electrode disposed within the ring acousto-optic modulator.

[0060] It should be understood, but not limited to, that photons present in this arrangement of the ring acousto-optic modulator are reflected and scattered by the surfaces of the acousto-optic elements and are at least partially confined within the space between said surfaces, i.e., the cavity within the ring acousto-optic modulator. This increases the possibility of photons interacting with the medium to be processed. Furthermore, due to various physical phenomena that may cause wavelength shifts and photon pulse variations, this results in a wide range of possible photochemical reactions in the medium to be processed, further improving processing efficiency.

[0061] In the context of this specification, the term cavity refers to the volume of the medium to be processed that is available within a space at least partially defined or restricted by one or more acousto-optic modulators as described herein.

[0062] This objective is also achieved by an apparatus for processing a medium, particularly air. The apparatus includes at least one arrangement and processing chamber as disclosed herein. The processing chamber defines an interior cavity and includes at least one arrangement of an acousto-optic modulator and electrodes. The processing chamber also includes an inlet in fluid communication with the interior cavity and including a first opening near a first end of the processing chamber, and an outlet in fluid communication with the interior cavity and including a second opening near a second end of the processing chamber. A flow path exists between the inlet and the outlet through the interior cavity.

[0063] While it is undesirable to be confined to a specific theory, the nature of the particles and electromagnetic radiation believed to be confined within the processing chamber is highly diverse, including ions, electrons, microwaves, acoustic waves, Alfvén waves, and / or electromagnetic radiation ranging from infrared (IR) to ultraviolet (UV) light. The confinement and reflection of plasma within the processing chamber results in the formation of numerous high-energy, short-pulse laser filaments, which are absorbed by the medium or the substances contained within it and affect the processing of the medium. The ability to return most of these particles and waves to the interior of the processing chamber can determine the performance of the system. Therefore, it is necessary to prevent leakage within the processing chamber, which can become a source of electromagnetic interference, and it is essential to have walls resistant to degradation, particularly those resistant to UV degradation.

[0064] Specifically, the device includes an annular acousto-optic modulator whose longitudinal axis is substantially parallel to the average flow direction of the medium to be processed through the processing chamber.

[0065] The advantage of this device is that the media handling achieved is energy-efficient. This device can be integrated into ventilation and / or air conditioning systems, but it can also be used as a stand-alone unit, particularly for air handling.

[0066] In a preferred embodiment of the apparatus disclosed herein, the processing chamber includes an amplification structure, particularly a perforated amplification structure. The amplification structure is conical in the average flow direction of the medium. Preferably, the amplification structure is formed as an epicycloid. The amplification structure includes at least a partial, preferably complete, diamond coating.

[0067] As used herein, the term perforation refers to an opening in the amplified structure through which air and / or plasma can pass. The conical shape of the amplified structure has the advantage that the gaseous medium flow is directed to one or more processing chamber outlets, which increases the plasma density downstream of the amplified structure, i.e., the number of charged particles in the plasma, and thus improves the processing efficiency.

[0068] In a preferred embodiment of the device disclosed herein, the surface of the acousto-optic element of the ring acousto-optic modulator is formed as an epicycloid according to the amplification structure.

[0069] The advantage of this structure is that the surface of the acousto-optic modulator and the electromagnetic radiation incident on the surface of the acousto-optic modulator are optimally dispersed, thereby improving the processing effect.

[0070] Preferably, a voltage can be applied to the amplification structure in such a way that the amplification structure is the counter electrode of the electrode contained in the processing chamber, particularly in such a way that the electrode is the cathode and the amplification structure is the anode.

[0071] In a preferred embodiment of the apparatus disclosed herein, the acousto-optic modulator is disposed on the inner wall of the processing chamber. In this embodiment, the cavity is filled with light during the intended operation of the apparatus to allow continuous processing of the medium flowing through the processing chamber.

[0072] This has the advantage of handling all media introduced into the processing chamber.

[0073] In a preferred embodiment, the apparatus disclosed herein is configured to process a gaseous medium and further includes means for introducing a liquid into the gas stream to be processed.

[0074] Preferably, the liquid is introduced in the form of droplets with a diameter between 8 and 12 micrometers.

[0075] To avoid being bound by theory, it is currently assumed that the effect of the electromagnetic pulse on the droplet surface causes a pressure gradient in each droplet, which ultimately leads to the droplet implosion and emission of a shock wave, which in turn accelerates the molecules and / or particles, such as electrons, present in the processing chamber.

[0076] By injecting droplets within a specified size range, the effects can be optimized and the treatment of the medium can be made particularly effective.

[0077] This objective is further achieved through the acousto-optic modulator as disclosed herein, and particularly in the apparatus disclosed herein, for use in processing media, especially air.

[0078] This objective is further achieved through the use of acousto-optic modulators as disclosed herein, particularly in devices as disclosed herein, for shortening the duration of optical pulses and / or increasing the energy of photons incident on an acousto-optic medium.

[0079] This objective is further achieved through the use of acousto-optic modulators as disclosed herein, and particularly in devices as disclosed herein, for the synthesis of organic molecules.

[0080] In particular, the organic molecule may be an amino acid, which is preferably synthesized at least in part using a combustion gas selected from the group consisting of carbon dioxide and nitrogen oxides.

[0081] This objective is further achieved through the use of acousto-optic modulators as disclosed herein, particularly in devices as disclosed herein, for the production of hydrogen from water, alcohols, and / or hydrocarbons. Attached Figure Description

[0082] The invention will be explained in further detail with reference to the accompanying drawings, wherein the same reference numerals are used to refer to the same or similar elements.

[0083] Figure 1 A perspective view of the acousto-optic modulator according to the present invention;

[0084] Figure 2 :along Figure 1 The layered structure of the acousto-optic modulator shown by the dashed line b;

[0085] Figure 3 Another type of acousto-optic modulator along Figure 1 The layered structure in the form of a decomposition diagram of the dashed line b;

[0086] Figure 4 Longitudinal cross-section of the arrangement of the acousto-optic modulator and electrodes;

[0087] Figure 5 Cross-section of the arrangement of the acousto-optic modulator and electrodes;

[0088] Figure 6 Longitudinal cross-section of the device according to the present invention. Detailed Implementation

[0089] Figure 1 A perspective view of the acousto-optic modulator (10) as disclosed herein is shown. The acousto-optic modulator (20) includes a piezoelectric transducer (20) forming a laminate and an acousto-optic element (30). In this example, the acousto-optic modulator (10) is housed within a circular housing, so only the electrodes (21) of the piezoelectric transducer (20) facing away from the acousto-optic element (30) and the surface (34) of the acousto-optic element (30) opposite thereto are visible in this figure. The detailed structure of the acousto-optic modulator (10) along dashed line b is shown below. Figure 2 and Figure 3 A more detailed description follows. Furthermore, the average flow direction of the medium (90) to be treated is indicated by the dashed line a.

[0090] Figure 2The layered structure of the acousto-optic modulator (10) is schematically shown as a cross-section along the dashed line b. Starting from the surface (34) of the acousto-optic element (30) facing the medium to be processed and in the direction of the piezoelectric transducer (20), the material sequence in this embodiment of the acousto-optic modulator (10) initially consists of a bi-periodic structure of knitted glass fiber fabric (31) and optical silicone resin (32), which together constitute the acousto-optic element (30). The fabrication of the acousto-optic element (30) will be described in more detail later. A first electrode (22) is directly connected to the acousto-optic element (30), which is composed of, for example, an aluminum foil sheet with a thickness of about 15 micrometers commonly used in households. The first electrode (22) is connected to a dielectric material (23) via a contact element (25), which is composed of, for example, glass fiber fabric. The dielectric material (23) of the piezoelectric transducer (20) can be, for example, a mixture of palm wax, rosin, and beeswax. Another material sequence in the acousto-optic modulator (10) consists of another contact element (24) and a second electrode (21), wherein the materials used for these elements (21, 24) may be the same as or different from those materials of the first electrode (22) and the first contact element (25). The second electrode (21) of the acousto-optic element (30) and the surface (34) are located on opposite sides of the acousto-optic modulator (10), that is, the second electrode (21) and the surface (24) form the two outermost layers of a laminate.

[0091] Figure 3 Another embodiment of the acousto-optic modulator (10) is shown in exploded view, revealing a clearer view of its layered structure. Specifically, Figure 3 The acousto-optic element layer (30) is schematically shown, comprising a fabric (31) with yarns made of a dielectric material. The yarns form a bi-periodic structure, wherein the gaps between the yarns are filled with a dielectric material (32), particularly a dielectric resin, whose refractive index differs from that of the material used to prepare the fabric (31) having the bi-periodic structure. In this example, the dielectric resin (32) used to impregnate and fill the fabric (31) also includes Raman scattering crystals (33) dispersed in the resin. The acousto-optic element (30) thus formed is laminated with a piezoelectric transducer (20), which comprises a dielectric material (23) sandwiched between two electrodes (21, 22).

[0092] Figure 4A longitudinal section of the arrangement (50) of the acousto-optic modulator (10) and electrodes (40) is shown. In this representation, the average flow direction of the medium to be treated will be substantially in the drawing plane (not shown). In this example, the arrangement (50) is annular, i.e., the acousto-optic modulator (10) and the amplifier structure (41) are arranged concentrically, with the electrodes (40) disposed between the annular acousto-optic modulator (10) and the amplifier structure (41). The space (102) between the surface (34) of the acousto-optic modulator (10) and the amplifier structure (41) is where the molecules in the medium to be treated interact with the plasma. The medium to be treated (90) enters the space (102) through the processing chamber inlet (103) and exits the space (102) through the processing chamber outlet (104). The electrodes (40) include at least a partial diamond coating to enhance the treatment effect as described above.

[0093] Figure 5 It shows Figure 4 The arrangement (50), although a cross-sectional view. In this example, the surface (34) of the acousto-optic modulator (10) facing the processing space (102) is formed as an epicycloid according to the magnified structure (41). Not wanting to be bound by theory, it is assumed that by forming the sidewalls of the processing chamber, i.e. the surface (34) of the acousto-optic modulator (10), in a parabolic shape, sound waves can be effectively dispersed and reflected inside the processing chamber. In this way, the processing effect can be improved.

[0094] Figure 6 A longitudinal section of the apparatus (100) disclosed in WO 2012 / 028687 is shown, but with an acousto-optic modulator as disclosed herein. The apparatus (100) for processing a medium (90), particularly air (91), includes at least one arrangement (50) of an acousto-optic modulator (10) and electrodes (40) in a processing chamber (101), the processing chamber (101) defining an inner cavity (102), an inlet (103) in fluid communication with the inner cavity (102) and a first opening near a first end of the processing chamber (101), and an outlet (104) in fluid communication with the inner cavity (102) and a second opening near a second end of the processing chamber (101). The apparatus also includes a flow path (a) between the inlet (103) and the outlet (104) and through the inner cavity (102).

[0095] Before entering the processing chamber (101), the gaseous or liquid medium (90) to be processed is conveyed to the plasma generating apparatus (60) via an external device not shown in the schematic diagram. However, the conveying device may include, for example, one or more fans. The plasma generating apparatus (60) may be a plasma chamber and preferably includes a generator for generating electromagnetic radiation with frequencies in the microwave range.

[0096] The medium (90) enters the plasma generating apparatus (60) through the plasma device inlet (61). Within the plasma generating apparatus (60), plasma (1) is generated in the medium (90), i.e., air (91) is converted into plasma (1). It is conceivable that the plasma (1) has atmospheric pressure, i.e., a pressure in the range of 0.8 bar to 1.2 bar, and a temperature in the range of 15°C to 45°C. The plasma (1) is conveyed through the plasma device outlet (62) into a dielectric structure (63), which can be formed as a tube with a circular, rectangular, or elliptical cross-section. In particular, such a structure can be formed with any cross-section. The tube is also preferably contained in or coated with silica. This fused silica tube (63) allows the plasma (1) formed in the plasma generating apparatus (60) to be conveyed to the processing chamber inlet (103) and the processing chamber (101), respectively. This has the effect of accelerating at least a portion of the electrons in the plasma (1). The fused silica tube (63) has a tapered cross-section in the medium flow direction (a), which means that the flow cross-section of the tube is reduced at least in the tube cross-section in the medium flow direction. This is used to generate turbulence in the medium flow and plasma, thereby contributing to the “mixing” of the plasma (1). Thus, a synergistic effect can be achieved to sustain and modify the plasma (1) over a longer length, thereby extending the time that the plasma (1) can react with the medium (90). Not wanting to be bound by theory, it is further assumed that at least a portion of the electrons in the plasma are accelerated to higher velocities by surface waves in the dielectric structure (63), which also leads to improved processing.

[0097] In the processing chamber (101), an acousto-optic modulator (10) is arranged on the inner wall (105) of the processing chamber (101), wherein the volume (102) existing between the acousto-optic modulators (10), i.e., the cavity (102), comprises a plurality of electrodes (40). The electrodes (40) are preferably coated with a full diamond coating. A voltage of 4 to 17 kV is applied between the electrodes (40) using a power source (not shown). Preferably, the voltage applied between the electrodes (40) is between 8 and 12 kV. This serves to support plasma generation and maintain the plasma (1) present in the processing chamber (101). The processing chamber (101) thus allows for an increase in the duration of the interaction between the plasma (1) and the medium (90), which increases the processing effect and makes the device (100) more energy-efficient.

[0098] Another advantage of the processing chamber (101) disclosed herein is the amplification of the number of photons, i.e., the types of photons in the plasma, during the intended operation of the device (100). In other words, the processing chamber (101) is filled with plasma (1), which interacts with contaminants such as airborne microorganisms or chemical toxins and thus reduces the amount of such contaminants in the plasma (1). Therefore, the plasma (1) exiting the processing chamber outlet (104) contains a smaller amount of contaminants. In particular, the device (100) as described herein allows for continuous processing of the medium (90) flowing through the processing chamber (101). Preferably, the inner wall (105) of the processing chamber (101) comprises a diamond coating.

[0099] In this example, starting from the processing chamber inlet (103) and moving along the flow direction (a) of the medium (90), the inner wall (105) comprises a first portion having a basic curved surface and a second portion having a flat surface formed by the surface of the acousto-optic element (34) of the acousto-optic modulator (10) facing the inner cavity. The processing chamber (101) also includes an amplified structure (41) in the form of an epicycloid and a cylindrical structure (not shown) arranged in the volume surrounded by the amplified structure (41). Both the amplified structure (41) and the cylindrical structure have a diamond coating.

[0100] In a preferred embodiment, the apparatus (100) disclosed herein is configured to process a gaseous medium (91) and further includes means (not shown) for introducing a liquid (92) into the gas stream to be processed.

[0101] The following describes a method for fabricating an acousto-optic modulator as disclosed herein. The method for fabricating the acousto-optic modulator includes the following steps: i) providing a mold comprising a first electrode and a second electrode, the electrodes being spaced apart and each electrode defining a wall of the mold; ii) optionally, providing two contact elements, one on each side of the electrodes facing each other; iii) connecting the electrodes to a voltage source; iv) providing a first dielectric material in a molten state; v) filling the mold with the molten first dielectric material; vi) applying a DC voltage to the two electrodes; vii) maintaining the voltage during cooling of the first dielectric material, at least until the molten first dielectric material has completely solidified; viiii) providing a fabric made of the dielectric material, wherein the fabric comprises a bi-periodic structure; and ix) impregnating the fabric with a dielectric material having a refractive index different from that of the fabric dielectric material.

[0102] Because electrets attract charged dust particles and various ions outdoors and quickly lose their charge, they must be stored in a tightly protected environment, such as by wrapping them in aluminum foil.

[0103] Therefore, it is preferable that the dielectric material in the piezoelectric transducer is covered by the electrodes as much as possible and that the contact between the dielectric material and the electrodes is as large as possible.

[0104] Preferably, the electret is manufactured in a mold, which will later be formed as part of an apparatus including an acousto-optic modulator.

[0105] By fabricating the electret directly in a mold that essentially comprises the required size of the final piezoelectric transducer—that is, the first dielectric material polarized in an electric field—the electret does not need to be separated from the electrode after its fabrication, which allows it to retain its charge particularly well.

[0106] Another approach is to pour molten first dielectric material into a mold, which is placed on an aluminum foil located on an insulating metal electrode. A second aluminum foil is then placed on top of the mold containing the molten material, and a cover electrode is placed on top of the aluminum foil.

[0107] After the mold is filled with melt, a high voltage is applied between the two electrodes, and the first dielectric material is allowed to cool for approximately 1 hour under the influence of the applied voltage until it is completely solid. The voltage is then turned off, and if necessary, the electret thus obtained can be removed from the mold.

[0108] Preferably, the connection between the fabric with the dual-periodic structure and the piezoelectric transducer is established during the impregnation step.

[0109] For example, it is conceivable to place a glass fiber knitted fabric on the contact surface having substantially the same dimensions as the contact surface of the piezoelectric transducer to be covered by the acousto-optic element, and to impregnate the glass fiber knitted fabric with optical silicone resin before and / or afterward.

[0110] If desired, the fiberglass knitted fabric can also be fixed to a portion or the entire contact surface of the piezoelectric transducer prior to the impregnation step, for example, with assembled silicone resin.

[0111] The advantage of this approach is that the fabric can be quickly and securely fixed in the desired shape, for example, if the piezoelectric transducer is not flat, if the acousto-optic modulator is manufactured at different stations and the semi-finished product must be transported between these stations, or if the geometry of the acousto-optic modulator requires the fabric to resist gravity. In such cases, the fiberglass knitted fabric is actually impregnated with another dielectric material, such as optical silicone, at a later stage.

[0112] In a preferred embodiment, Raman scattering crystals, such as diamond nanoparticles, are added to the dielectric material used for impregnating the fabric. In this case, it is recommended that these particles be mixed into the dielectric material, such as optical silicone, prior to the impregnation step to achieve a uniform colloidal dispersion of the Raman scattering crystals in the dielectric material.

[0113] Depending on the dielectric material used for impregnating the fabric, cross-linked dielectric materials are preferred to obtain higher mechanical strength of the acousto-optic elements and / or improved adhesion between the dielectric material and the fabric. Cross-linking can be achieved, for example, by ultraviolet radiation, in which case the dielectric material resin used for impregnation preferably contains a photoinitiator and / or the fabric is treated with a compound containing a photoinitiator prior to impregnation.

Claims

1. An acousto-optic modulator (10), the acousto-optic modulator comprising: - A piezoelectric transducer (20) having a first electrode (21), a second electrode (22), and a first dielectric material (23) disposed between and in contact with the electrodes (21, 22); and - Acousto-optic element (30), comprising at least two other dielectric materials (31, 32) with different refractive indices. The piezoelectric transducer (20) and the acousto-optic element (30) are laminated together, wherein at least one of the other dielectric materials (31, 32) of the acousto-optic element (30) is a dielectric fabric with a dual-periodic structure.

2. The acousto-optic modulator (10) according to claim 1, wherein the acousto-optic modulator (10) is used in a device (100) for processing a medium (90).

3. The acousto-optic modulator (10) according to claim 2, wherein the medium (90) is air (91).

4. The acousto-optic modulator (10) according to claim 1, further comprising two contact elements (24, 25) configured to ensure contact between the first dielectric material (23) and the electrodes (21, 22).

5. The acousto-optic modulator (10) according to claim 1, wherein, The materials of the first electrode (21) and / or the second electrode (22) are selected from metals, activated carbon, graphene and ionomers.

6. The acousto-optic modulator (10) according to claim 5, wherein the first electrode (21) and / or the second electrode (22) are made of aluminum foil with a thickness between 4 and 100 μm.

7. The acousto-optic modulator (10) according to claim 5, wherein the first electrode (21) and / or the second electrode (22) are made of aluminum foil with a thickness between 4 and 20 μm.

8. The acousto-optic modulator (10) according to any one of claims 1 to 7, wherein, The first dielectric material (23) of the piezoelectric transducer (20) comprises at least one natural wax selected from the group consisting of: palm wax, rosin, sugarcane wax, glyceryl rosin, lanolin, shellac wax, tallow, lignite wax, ceresin, whale wax, beeswax, crown palm wax, Japanese wax, bayberry wax, candelilla wax, Chinese wax, Chinese insect wax, and combinations thereof.

9. The acousto-optic modulator (10) according to claim 8, wherein, The first dielectric material (23) of the piezoelectric transducer (20) is selected from the group consisting of palm wax, rosin, beeswax and combinations thereof.

10. The acousto-optic modulator (10) according to any one of claims 1 to 7, wherein, The first dielectric material (23) of the piezoelectric transducer (20) is selected from the group consisting of ZnO, LiNb3, LiTaO3, SiO2, quartz, TiO2, Si, SiN, AlN, GaN and SrTiO3.

11. The acousto-optic modulator (10) according to claim 4, wherein, At least one of the two contact elements (24, 25) includes dielectric fabric.

12. The acousto-optic modulator (10) according to claim 11, wherein, The dielectric fabric is a glass fiber knitted fabric.

13. The acousto-optic modulator (10) according to any one of claims 1 to 7, wherein, The acousto-optic element (30) comprises a glass fiber knitted fabric impregnated with silicone resin.

14. The acousto-optic modulator (10) according to claim 13, wherein, The silicone resin includes at least one type of Raman scattering crystal (33).

15. The acousto-optic modulator (10) according to claim 14, wherein, The Raman scattering crystal (33) is selected from the group consisting of diamond, corundum and / or quartz.

16. The acousto-optic modulator (10) according to claim 14, wherein, The content of the Raman scattering crystal (33) in the silicone resin is 0.1-2% by weight and / or the size of the Raman scattering crystal (33) is between 4 and 1000 nm.

17. The acousto-optic modulator (10) according to claim 16, wherein, The size of the Raman scattering crystal (33) is between 8 and 170 nm.

18. The acousto-optic modulator (10) according to claim 13, wherein, The surface (34) of the acousto-optic element (30) is configured to form SiO2 and / or SiN by the action of a plasma containing oxygen and / or nitrogen on the silicone resin at the surface. x Plasma microscope.

19. The acousto-optic modulator (10) according to any one of claims 1 to 7, wherein, The total thickness of the laminate consisting of the piezoelectric transducer (20) and the acousto-optic element (30) is between 4 and 80 mm.

20. The acousto-optic modulator (10) according to any one of claims 1 to 7, wherein, The total thickness of the laminate consisting of the piezoelectric transducer (20) and the acousto-optic element (30) is between 20 and 40 mm.

21. An arrangement (50) of at least one acousto-optic modulator (10) according to any one of claims 1 to 7 and at least one electrode (40) disposed within the acousto-optic modulator (10), wherein, A space is formed between the surface of the acousto-optic modulator (10) and the electrode (40), wherein a medium (90) can be introduced, wherein the electrode (40) includes at least a partial coating having a Raman scattering crystal (33).

22. The arrangement (50) according to claim 21, wherein, The acousto-optic modulator (10) is a ring acousto-optic modulator.

23. The arrangement (50) according to claim 21, wherein the electrode (40) comprises a complete coating.

24. The arrangement (50) according to claim 21, wherein, The Raman scattering crystal (33) is diamond.

25. An apparatus (100) for processing a medium (90), the apparatus (100) comprising at least one arrangement (50) according to claim 21, wherein the apparatus (100) further comprises: A processing chamber (101) defines an inner cavity (102); an inlet (103) in fluid communication with the inner cavity (102) and including a first opening near a first end of the processing chamber (101); an outlet (104) in fluid communication with the inner cavity (102) and including a second opening near a second end of the processing chamber (101); and a flow path (a) between the inlet (103) and the outlet (104) and through the inner cavity (102).

26. The apparatus (100) according to claim 25, wherein, The medium (90) is air (91).

27. The apparatus (100) according to claim 25, wherein, The acousto-optic modulator (10) is arranged on the inner wall (105) of the processing chamber (101), wherein the inner cavity is filled with light during the intended operation of the device (100) to allow continuous processing of the medium (90) flowing through the processing chamber (101).

28. The apparatus (100) according to any one of claims 25 to 27, wherein, The device (100) is configured to process a gaseous medium (91), and the device (100) further includes means for introducing a liquid (92) into the gas stream to be processed.

29. The apparatus (100) according to claim 28, wherein the liquid (92) is introduced in the form of droplets with a diameter between 8 and 12 micrometers.

30. Use of the acousto-optic modulator (10) according to any one of claims 1 to 20 for processing a medium (90).

31. Use of the apparatus (100) according to any one of claims 25 to 29 for processing a medium (90).

32. The medium (90) is air (91) according to claim 30 or 31.

33. The use of the acousto-optic modulator (10) according to any one of claims 1 to 20 for shortening the duration of an optical pulse and / or increasing the photon energy incident on the acousto-optic element (30).

34. Use of the device (100) according to any one of claims 25 to 29 for shortening the duration of the optical pulse and / or increasing the photon energy incident on the acousto-optic element (30).

35. Use of the acousto-optic modulator (10) according to any one of claims 1 to 20 for the synthesis of organic molecules.

36. Use of the apparatus (100) according to any one of claims 25 to 29 for the synthesis of organic molecules.

37. The use according to claim 35 or 36, wherein the organic molecule is an amino acid.

38. The use according to claim 35 or 36, using a combustion gas selected from the group consisting of carbon dioxide and nitrogen oxides.

39. Use of the acousto-optic modulator (10) according to any one of claims 1 to 20 for generating hydrogen from water, alcohol and / or hydrocarbons.

40. Use of the apparatus (100) according to any one of claims 25 to 29 for generating hydrogen from water, alcohol and / or hydrocarbons.

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