Acousto-optic modulator

Abstract

An acousto-optical modulator (10) comprising a piezoelectric transducer (20) having a first electrode (21), a second electrode (22), and a dielectric (23) arranged between the electrodes (21, 22) and in contact with the electrodes (21, 22), and an acousto-optical element (30) comprising at least two further dielectrics (31, 32) having refractive indices different from each other, wherein the piezoelectric transducer (20) and the acousto-optical element (30) are stacked together, and at least one of the further dielectrics (31, 32) of the acousto-optical element (30) is a dielectric textile having a double periodic structure.

Description

Technical Field

[0001] The present invention relates to acousto-optic modulators, devices consisting of acousto-optic modulators and electrodes, devices for treating media, and methods of using both the acousto-optic modulators and the devices to shorten the optical pulse duration and / or increase the photon energy, treat media, synthesize organic molecules, generate hydrogen from water and / or hydrocarbons, or optionally combine these according to the preamble of the independent claims.

Background Art

[0002] Various acousto-optic modulators are known from the prior art. For example, U.S. Patent Application Publication No. 2007 / 0171513 discloses an acousto-optic modulator comprising a single crystal silicon acousto-optic interaction medium and at least one transducer for emitting acoustic waves attached to the single crystal. However, such acousto-optic modulators typically require structures that are patterned with sub-micrometer accuracy, such as single crystals, which are usually quite expensive to manufacture, large in size, and / or not easily available in different shapes. Also, the brittleness or rigidity of the crystal structures makes it difficult, if not impossible, to adapt these periodic structures to non-uniform or shaped substrates.

[0003] Furthermore, it is also known from the prior art to use electromagnetic radiation, specifically ultraviolet (UV) light, to disinfect air in a treatment space. A system for purifying and removing contaminants from a fluid, which operates based on this principle, is known, for example, from European Registered Patent No. 1660211. Since the service life of the UV lamps used in such devices is limited, frequent replacement of these UV lamps may be required depending on the applied intensity and environmental conditions, which means a reduction in service life and additional effort for the user.

Summary of the Invention

[0004] Generally, the medium to be processed can be a gas, liquid, or gas / liquid mixture used to generate the plasma. The plasma is transported to a processing chamber to extend the duration of the interaction between the plasma and the medium to be processed. However, the processing time and / or intensity within the device, specifically within the processing chamber, may not be sufficient to achieve the desired processing results.

[0005] Therefore, the object of the present invention is to improve these and other shortcomings of the latest technology, specifically, to provide an acousto-optic modulator, an apparatus comprising an acousto-optic modulator and electrodes, and a device for processing a medium that enables energy-efficient and energy-effective processing, is inexpensive, and can be manufactured in a variety of shapes.

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

[0007] Without limiting the present invention, the term "processing" encompasses the degradation, synthesis, inactivation, or disruption of molecules, including biological structures such as proteins, pollen, mold spores, bacteria, viruses, and / or other microorganisms, that are incorporated into the medium being processed.

[0008] Furthermore, the term plasma in the context of this invention is understood as a gas and / or vapor that is dissociated into its components under the influence of an electric field. Plasma includes photons, ions, free electrons, free radicals, and neutral particles, specifically excited neutral particles. [Means for solving the problem]

[0009] This objective is achieved by the acousto-optic modulator, the apparatus comprising the acousto-optic modulator and electrodes, and the device for processing a medium, as described in the independent claim. Effective embodiments are the subject of the dependent claims.

[0010] According to the present invention, an acousto-optic modulator comprises a piezoelectric transducer having a first electrode, a second electrode, and a dielectric disposed between the electrodes in contact with the electrodes. To ensure contact between the dielectric and the electrodes, the piezoelectric transducer may optionally include two contact elements configured to ensure contact between the first dielectric and the two electrodes. The piezoelectric transducer further comprises an acousto-optic medium having at least two further dielectrics having different refractive indices. The piezoelectric transducer and the acousto-optic medium are stacked on top of each other. The acousto-optic medium includes at least one dielectric textile having a double periodic structure.

[0011] Remarkably, crystals in optical modulation can now be replaced by textiles featuring a normal structure, specifically by knitted glass fibers or any other material with a high dielectric constant. This makes it possible to realize large acousto-optical structures measuring tens of square meters, if desired or required. The flexibility of the textiles also enables the realization of complex acousto-optical modulator shapes. Furthermore, compared to known conventional structures whose size is limited to a few square centimeters, significant reductions in material and manufacturing costs are possible.

[0012] Piezoelectric transducers, known in modern technology, constitute a type of electroacoustic transducer that converts electric charge generated by some form of solid material into energy. For example, it is understood that a piezoelectric layer can generate acoustic waves.

[0013] Acousto-optic modulators utilize acousto-optic effects to diffract and alter the frequency of light using sound waves. Laser pulses vibrate a piezoelectric cell, generating sound waves within the glass. These can be hypothesized as periodically moving and compressing expansion and compression planes that change refractive index. The incident light is scattered outside the resulting periodic modulation of the refractive index (Brillouin scattering), producing interference similar to that generated in Bragg diffraction. This interaction can be considered as a four-wave mixing of phonons and photons.

[0014] While not bound by theory, it is assumed that the series of physical phenomena currently involved in simultaneously exposing an acousto-optic modulator, such as those disclosed herein, to an electrostatic field and pulsed electromagnetic radiation can be qualitatively explained as follows: 1) absorption of laser pulses by semiconductors, i.e., acousto-optic elements, generates photoexcited free carriers; 2) these unbalanced electrons and holes diffuse within the existing electrostatic field; 3) spatial separation of charges generates a dynamic electric field between electron clouds and holes; and 4) this dynamic field induces mechanical constraints within the piezoelectric transducer via the piezoelectric effect, thereby becoming the source of acoustic waves. The main difference between the piezoelectric materials used herein and conventional piezoelectric transducers is that the electric field applied to the material to generate acoustic waves is triggered optically rather than electrically, which allows the operating frequency of the devices described herein to be significantly extended to frequencies above GHz.

[0015] In the context of this specification, the term "double periodic" refers to a regular textile structure that can be defined by unit cells that periodically repeat in two directions across the knitted fabric (Grishanov et al., J. Knot Theory and its Ramifications, 18(2009), 1597-1622). Knitted textile structures are examples of double periodic structures in a thickened plane produced from bonded twisted yarns.

[0016] In one preferred embodiment, the acousto-optic modulator is part of a device for processing a medium, preferably air.

[0017] In one preferred embodiment, the acousto-optic modulator disclosed herein comprises a piezoelectric transducer and an acousto-optic element. The piezoelectric transducer comprises a first electrode, a second electrode, and a dielectric placed between the electrodes in contact with the electrodes. Optionally, the piezoelectric transducer further comprises two contact elements configured to ensure contact between the first dielectric and the electrodes. The acousto-optic modulator comprises two further dielectrics having different refractive indices. The piezoelectric transducer and the acousto-optic element are stacked on top of each other. One of the further dielectrics of the acousto-optic element is a dielectric textile having a double periodic structure.

[0018] Compared to the acousto-optic modulator described above, an acousto-optic modulator in which the acousto-optic element is made from only two different dielectrics, one of which is a textile with a double periodic structure, is easier and cheaper to manufacture.

[0019] The electrodes of the acousto-optic modulators disclosed herein are used to apply a voltage to a dielectric. While not theoretically bound, it is now understood that excitation of an electrode surface by a photon can enhance the scattering of that photon through a mechanism known as surface-enhanced Raman scattering (SERS). This can also increase the number of photons present in the processing chamber, as will be detailed later.

[0020] In one preferred embodiment of the acoustic-optic modulator disclosed herein, the first and / or second electrode material is selected from metals, activated carbon, graphene, and ionic polymers.

[0021] Such electrodes are readily available and can be manufactured in various shapes. Furthermore, the first and second electrode materials may have different compositions.

[0022] Preferably, the first and / or second electrodes are made of aluminum. Electrodes made from aluminum have the advantages of being relatively inexpensive and ductile. Furthermore, aluminum foil and suitable aluminum sheets are generally readily available. In addition, aluminum on the electret enhances Raman scattering and luminescence.

[0023] Similarly, although not bound by theory, this phenomenon, which can reach up to 15 times, can sometimes be explained by the enhancement of the local electric field applied to molecules and atoms. The origin of this enhancement lies in the coupling of laser light with electron density waves appearing near the surface of a given metal, preferably submicron or even nanometer in size. The electron density waves originate from the free electrons of the metal. The new particles formed by this coupling are called surface plasmons. If the resonance frequencies of these surface plasmons are in the visible range of the electromagnetic spectrum, the surface plasmons can be coupled to amplify the local electric field. Thus, the surface-enhanced Raman scattering (SERS) effect is primarily a result of the increase in the electromagnetic field generated at the metal surface. When the wavelength of the incident light is close to the plasma wavelength of the metal, conduction electrons at the metal surface are excited to delocalized electronic states corresponding to surface plasmon resonances. Molecules adsorbed on or near the surface are particularly sensitive to the electromagnetic field. In this context, normal vibrational modes at the surface are amplified most strongly.

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

[0025] By selecting the aluminum foil thickness as specified, vibrations generated within the transducer by the fluctuating RF drive signal applied to the electrode can be effectively transmitted to the adjacent acousto-optic medium. Specifically, the present invention allows for the use of household aluminum foil with a typical thickness of 10 to 15 μm.

[0026] In the context of this specification, the term thickness refers to the average thickness of the foil material. The acousto-optic modulator disclosed herein is characterized by a thermoelectret, which is prepared by placing a dielectric between two electrodes, applying a hinged DC potential to the dielectric or dielectric mixture to preserve it at an appropriate temperature for a long time, and then cooling the article to room temperature while maintaining the DC potential.

[0027] In the context of this specification, the term electret is understood as a dielectric layer in which the charge is (pseudo) permanent and thus generates a (pseudo) permanent electric field.

[0028] In a preferred embodiment of the acousto-optic modulator disclosed herein, the dielectric of the piezoelectric transducer comprises at least one natural wax selected from the group consisting of carnauba, rosin, sugarcane, glycerol ester of wood rosin, lanolin, shellac, tallow, montan, ozokerite, whale wax, beeswax, oricury, lacquer, barberry, candelilla, Chinese, China wax, and combinations thereof.

[0029] The listed dielectrics have the advantage of being natural products, especially environmentally friendly. However, of course, and according to the present invention, the dielectric can also consist of synthetic polymers such as polyvinylidene difluoride (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.

[0030] Preferably, the dielectric is selected from the group consisting of carnauba, rosin, beeswax, and combinations thereof.

[0031] The electrets manufactured from these materials can preserve their polarization state for a long time and are characterized by excellent processability, toughness, and flexibility.

[0032] In one preferred embodiment of the acousto-optic modulator disclosed herein, the dielectric of the piezoelectric transducer is selected from the group consisting of ZnO, LiNb3, LiTaO3, SiO2, quartz, TiO2, Si, SiN, AlN, GaN, and SrTiO3.

[0033] In one preferred embodiment of the acoustic-optic modulator disclosed herein, at least one of the contact elements is a dielectric textile.

[0034] The use of textiles as contact elements has the advantage that, due to their flexibility and stretchability, textiles are particularly good at compensating for the shrinkage that occurs when dielectrics cool, thus ensuring broad contact between each electrode and the dielectric between them.

[0035] Preferably, both contact elements are made of dielectric textiles. This enables optimal connection between the dielectric and the two electrodes sandwiching the dielectric.

[0036] Preferably, the dielectric textile used as a contact element includes glass fiber knit. Glass fiber knit has the advantage of being commercially available in a wide range of sizes and patterns that can be selected according to the needs of special applications.

[0037] Photonic crystals made from glass and silicon nitride have been proven to amplify fluorescence or luminescence by tens of times.

[0038] In one preferred embodiment, the acoustic-optic modulator disclosed herein comprises a glass fiber knit impregnated with a silicone resin.

[0039] Preferably, the silicone used to impregnate the glass fiber knit is an optical silicone. Advantages of optical silicones include high thermal stability, optical clarity, UV resistance, low shrinkage, and excellent moldability, which facilitate the manufacture of complex acousto-optic elements or acousto-optic modulators.

[0040] Although not bound by theory, filling the spaces between meshes of glass fiber knit with silicone resin can yield structures whose chemical composition varies depending on the location, similar to quantum well heterostructures used in the semiconductor industry.

[0041] A periodic glass fiber structure impregnated with silicon resin can also be considered a photonic crystal. A photonic crystal is a periodic dielectric structure that inhibits the propagation of photons at a given wavelength. Similar to the electron band gap in semiconductors, a photonic crystal is characterized by a photonic band gap, i.e., a periodic variation in dielectric constant that can be caused, for example, by containing periodically spaced holes within the material. This photonic band gap inhibits the propagation of photons of a given energy. More precisely, a two-dimensional photonic band gap prevents the propagation of light across a given frequency range and in all directions in a plane. Instead, this directs the synchrotron radiation out of the photonic crystal, increasing extraction efficiency.

[0042] To improve control over the direction of light emission, photonic crystals can also be placed on a type of mirror called a Bragg reflector. These mirrors then reflect the light emitted by the photoemission material back outwards.

[0043] In one preferred embodiment, the silicone resin used to fill the voids within the glass fiber knit preferably comprises at least one Raman scattering crystal selected from the group consisting of diamond, corundum, and / or quartz.

[0044] While not bound by theory, it is currently assumed that electromagnetic radiation, i.e., photons, are more efficiently dispersed by these scattering particles, thereby increasing the processing effect caused by said electromagnetic radiation. Specifically, Raman scattering of photons on crystals, i.e., inelastic scattering, helps amplify the number of photons, resulting in an increase in the energy, i.e., frequency, of at least some of the scattered photons. The use of the specified Raman scattering crystals is particularly preferred because these materials are readily available and relatively inexpensive.

[0045] Specifically with respect to 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). The present invention is not limited thereto, but it is now understood that primary and secondary electron-hole pairs are excited within a diamond coating and then recombine by emitting two photons, thus amplifying the number of photons incident on the acousto-optic element described herein.

[0046] As a substitute for natural diamonds, zirconium oxide and / or other synthetic diamonds can be used. Preferably, a diamond coating with nitrogen dopant is used.

[0047] It is technically known that doping diamond with nitrogen generates so-called charged nitrogen-vacancy color centers that can be excited by visible light, followed by luminescence (Han et al., Nano Letters 9(2009), 3323-3329). The present invention is not limited to this, but it is now understood that this can lead to more efficient photon dispersion in plasma.

[0048] Preferably, the content of the Raman scattering crystals in the silicone is 0.1 to 2 weight percent of the silicone resin. Alternatively, or additionally, the size of the Raman scattering crystals is 4 to 1000 nm, preferably 8 to 170 nm.

[0049] Compositions and particles having the above specifications are intended for the manufacture of particularly effective acousto-optic modulators.

[0050] Mirrors can be used as active optical elements to focus ultrashort light pulses onto a target. If this light has sufficiently high intensity, the latter will be powerfully ionized in a very short time by a strong electromagnetic field during the rise time of the pulse.

[0051] In one preferred embodiment of the acousto-optic modulator disclosed herein, the surface of the acousto-optic medium is SiO2 and / or SiN x The plasma mirror is configured to form a plasma mirror containing oxygen and / or nitrogen. The plasma mirror is produced by reacting a plasma containing oxygen and / or nitrogen with the silicone on the surface, i.e., the silicone layer defining the interface between the acousto-optic medium and the plasma.

[0052] Specifically, silica and silicon nitride (Si3N4) are well-established materials for photonic devices, exhibiting a wide transparent window from the visible to the mid-infrared. These materials possess the necessary qualities to effectively mirror plasma. Widely used in the fields of optics and microelectronics, these materials are known for their excellent electrical, mechanical, and thermal properties. Both silica and nitrides are produced by chemical vapor deposition (CMD) in microwave plasma ECR reactors. This method is a low-temperature deposition technique that allows for the production of high-quality dielectric layers without damaging the substrate.

[0053] While the acousto-optic modulator disclosed herein is in operation, the silicon surface of the acousto-optic element is constantly exposed to a vibrating plasma, as will be detailed later. This plasma, rich in oxygen and nitrogen, allows for the continuous reconstruction of the surface thin layers of silicon dioxide (SiO2) and silicon nitride (Si3N4) that constitute the solid support of the plasma mirror, similar to an autogenerative or self-healing effect.

[0054] The ability to form a plasma mirror at the interface between an acousto-optic medium and the volume covering it has the advantage of more strongly reflecting incident photons. Furthermore, electromagnetic radiation pulses incident on one plasma mirror can be focused onto another plasma mirror, this time even more powerfully, and thus to much higher intensities up to the relativistic interaction regime, thus enhancing the processing effect of the medium being treated. This other plasma mirror can also be considered to be part of the same elements as the first plasma mirror, for example, in the case of a ring-shaped acousto-optic modulator, as will be described in more detail later. In the relativistic interaction regime, the light field induces vibrational motion on the plasma mirror surface, which, due to the Doppler effect, induces periodic time distortion of the wave reflected by the mirror. As a result of this periodic distortion, the spectrum of the reflected light consists of the frequency of the incident laser, plus numerous higher harmonics of this frequency. This process, known as the relativistic vibrational mirror process, enables the emergence of high harmonics sufficient to obtain ultrashort pulses.

[0055] All composite processes occurring in the heterostructures disclosed herein contribute to the emergence of single photons, specifically, photopumping in diamond nanoparticles and luminescence in optical silicones, respectively.

[0056] In a preferred embodiment of the acousto-optic modulator disclosed herein, the total thickness of the laminate comprising the piezoelectric transducer and the acousto-optic element is 4 to 80 mm, preferably 20 to 40 mm.

[0057] The prior objective is further achieved by an apparatus comprising at least one acousto-optic modulator and at least one electrode as disclosed herein. A space is formed between the surface of the acousto-optic modulator and the electrode into which a medium can be introduced. The electrode includes at least one partial coating, preferably a complete coating, of a Raman scattering crystal, specifically diamond.

[0058] Preferably, the apparatus includes a ring-shaped acousto-optic modulator as described herein and at least one electrode positioned inside the ring-shaped acousto-optic modulator.

[0059] While photons present within such a ring-type acousto-optic modulator are reflected and scattered by the surfaces of the acousto-optic elements, at least some remain confined within the space between these surfaces, i.e., the lumen inside the ring-type acousto-optic modulator. This is understood to increase the probability of interaction between the photons and the medium being processed, but this is not always the case. Furthermore, wavelength shifts and photonic pulse fluctuations can occur due to various physical phenomena, which can lead to a wide range of photochemical reactions in the medium being processed, further increasing the efficiency of the processing.

[0060] In the context of this specification, the term lumen means the volume available for the medium to be processed within a space at least partially defined or limited by one or more acousto-optic modulators described herein.

[0061] The aforementioned objective is further achieved by a device for processing a medium, specifically air. The device comprises at least one apparatus disclosed herein and a processing chamber. The processing chamber defines a lumen and comprises at least one apparatus comprising an acousto-optic modulator and electrodes. The processing chamber further comprises an inlet having a first opening that is in fluid communication with the lumen and adjacent to a first end of the processing chamber, and an outlet having a second opening that is in fluid communication with the lumen and adjacent to a second end of the processing chamber. Between the inlet and the outlet, there exists a flow path through the lumen.

[0062] While not limited to specific theories, it is certain that the properties of particles and electromagnetic radiation to be confined within the processing chamber are extremely diverse, including ions, electrons, microwaves, acoustic waves, Alfvén waves, and / or electromagnetic radiation ranging from infrared (IR) to ultraviolet (UV) light. Plasma confinement and reflection within the processing chamber will result in the formation of numerous high-energy short-pulse laser filaments, which are absorbed by the medium or its constituent materials to achieve processing of the medium. The ability to return most of these particles and waves into the processing chamber is likely to determine the system performance. Therefore, it is necessary to prevent leakage within the processing chamber, which can also cause electromagnetic interference, and to have walls that are resistant to degradation, specifically to decomposition by UV light.

[0063] Specifically, the device includes a ring-shaped acousto-optic modulator having a longitudinal axis substantially parallel to the mean flow direction of the medium to be processed, via a processing chamber.

[0064] Such devices have the advantage that the medium treatment achieved is energy-efficient. While such devices can be integrated into ventilation and / or air conditioning systems, they can also be used as standalone devices, specifically for air treatment.

[0065] In one preferred embodiment of the device disclosed herein, the processing chamber comprises an amplification structure, specifically a perforated amplification structure. The amplification structure is formed conically in the mean flow direction of the medium. Preferably, the amplification structure is formed as an outer cycloid. The amplification structure comprises at least a partial, preferably complete, diamond coating.

[0066] As used herein, the term "perforated" refers to an opening in an amplification structure through which air and / or plasma can pass.

[0067] The conical shape of the amplification structure directs the flow of the gaseous medium towards one or more processing chamber outlets, which increases the plasma density downstream of the amplification structure, i.e., the number of charged particles in the plasma, and thus enhances the processing effect.

[0068] In one preferred embodiment of the devices disclosed herein, the surface of the acousto-optic element of the ring-shaped acousto-optic modulator is formed as an outer cycloid in accordance with the amplification structure.

[0069] Such a structure has the advantage of optimally dispersing the electromagnetic radiation incident on the surface of the acousto-optic modulator, thereby enhancing the processing effect.

[0070] Preferably, a voltage can be applied to the amplification structure such that the amplification structure functions as a counter electrode to an electrode contained within the processing chamber, specifically such that the electrode functions as a cathode and the amplification structure functions as an anode.

[0071] In one preferred embodiment of the device disclosed herein, an acousto-optic modulator is positioned on the inner wall of the processing chamber. In this embodiment, during the intended operation of the device, the lumen is filled with light to enable continuous processing of the medium flowing through the processing chamber.

[0072] This has the advantage that all the medium introduced into the processing chamber is processed. In one preferred embodiment, the device disclosed herein is configured to process a gaseous medium and further comprises means for introducing a liquid into the gaseous flow to be processed.

[0073] Preferably, the liquid is introduced in the form of droplets with a diameter of 8 to 12 micrometers. While not bound by theory, it is currently assumed that the electromagnetic pulse shock applied to the droplet surface creates a pressure gradient within each droplet, which ultimately causes the droplet to implode and emit a shock wave, which in turn accelerates molecules and / or particles, such as electrons, present in the processing chamber.

[0074] Injecting droplets within a specified size range can optimize the effect, and the medium treatment becomes particularly effective.

[0075] The aforementioned objective is further achieved by the use of the acousto-optic modulators disclosed herein, specifically in the devices disclosed herein, for processing a medium, specifically air.

[0076] The aforementioned objective is further achieved by the use of the acousto-optic modulators disclosed herein, specifically in the devices disclosed herein, for reducing the duration of optical pulses and / or increasing the energy of photons incident on an acousto-optic medium.

[0077] The aforementioned objective is further achieved by the use of the acousto-optic modulators disclosed herein, specifically in the devices disclosed herein, for the synthesis of organic molecules.

[0078] Specifically, the organic molecule may be an amino acid, which is preferably synthesized using a combustion gas selected from the group consisting of carbon dioxide and nitrous oxide, at least in part.

[0079] The aforementioned objective is further achieved by the use of the acousto-optic modulators disclosed herein, specifically in the devices disclosed herein, for producing hydrogen from water, alcohol, and / or hydrocarbons.

[0080] The present invention is further illustrated in more detail by drawings, in which similar reference numerals refer to the same or similar elements. [Brief explanation of the drawing]

[0081] [Figure 1] This is a perspective view of the acoustic-optical modulator according to the present invention. [Figure 2] The layered structure of the acousto-optic modulator is shown along the dashed line b in Figure 1. [Figure 3] This figure shows the layered structure of another acousto-optic modulator in an exploded view, along the dashed line b in Figure 1. [Figure 4] This is a longitudinal cross-sectional view of a device consisting of an acoustic-optic modulator and electrodes. [Figure 5] This is a cross-sectional view of a device consisting of an acoustic-optic modulator and electrodes. [Figure 6] This is a longitudinal cross-sectional view of the device according to the present invention. [Modes for carrying out the invention]

[0082] Figure 1 is a perspective view showing an acousto-optic modulator (10) disclosed herein. The acousto-optic modulator (20) comprises a piezoelectric transducer (20) and an acousto-optic element (30) forming a laminate. In this embodiment, the acousto-optic modulator (10) is incorporated into a circular housing, and therefore, in this figure, only the electrode (21) of the piezoelectric transducer (20) facing away from the acousto-optic element (30) and the surface (34) of the acousto-optic element (30) on the opposite side are visible. The detailed structure of the acousto-optic modulator (10) along the dashed line b will be described in more detail below in Figures 2 and 3. Furthermore, the average flow direction of the medium (90) to be processed is indicated by the dashed line a.

[0083] Figure 2 shows a schematic cross-sectional view of the layered structure of the acousto-optic modulator (10) along the dashed line b. Starting from the surface (34) of the acousto-optic element (30) facing the medium to be processed, the series of materials in this embodiment of the acousto-optic modulator (10) in the direction of the piezoelectric transducer (20) first consist of a double periodic structure of glass fiber knitting (31) and optical silicone (32), which together form the acousto-optic element (30). The preparation of the acousto-optic element (30) will be described in more detail later. The first electrode (22) is directly connected to the acousto-optic element (30), and this electrode consists of, for example, a common household aluminum foil piece with a thickness of about 15 micrometers. The first electrode (22) is connected to the dielectric (23) via a contact element (25) made of, for example, glass fiber textile. The dielectric (23) of the piezoelectric transducer (20) may be, for example, a mixture of carnauba wax, rosin, and beeswax. A further set of materials in the acousto-optic modulator (10) consists of further contact elements (24) and a second electrode (21), the materials used for these elements (21, 24) may be the same as or different from those of the first electrode (22) and the first contact element (25). The second electrode (21) and the surface (34) of the acousto-optic element (30) are positioned on the opposite side of the acousto-optic modulator (10), in other words, the second electrode (21) and the surface (24) form the two outermost layers of the laminate.

[0084] Figure 3 shows another layered structure of the acousto-optic modulator (10) in an exploded style that allows for a better understanding of the layered structure of the acousto-optic modulator (10). Specifically, Figure 3 schematically shows an acousto-optic element layer (30) comprising a textile (31) in which the braided yarns are made of a dielectric. The braided yarns form a double periodic structure, and the gaps between the braided yarns are filled with a dielectric (32), specifically a dielectric resin, which has a refractive index different from that of the material used to prepare the textile (31) having a double periodic structure. In this embodiment, the dielectric resin (32) used to impregnate and fill the textile (31) further includes Raman scattering crystals (33) dispersed within the resin. The thus formed acousto-optic element (30) is laminated with a piezoelectric transducer (20) which includes a dielectric (23) sandwiched between two electrodes (21, 22).

[0085] Figure 4 shows a longitudinal cross-sectional view of a device (50) consisting of an acousto-optic modulator (10) and an electrode (40). In this figure, the mean flow direction of the medium to be processed is substantially within the drawing plane (not shown). In this embodiment, the device (50) is ring-shaped, that is, the acousto-optic modulator (10) and the amplifier structure (41) are arranged concentrically with the electrode (40) placed between the ring-shaped 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 interaction between molecules in the medium to be processed and the plasma occurs. The medium to be processed (90) enters the space (102) via the processing chamber inlet (103) and exits the space (102) via the processing chamber outlet (104). The electrode (40) includes at least one partial diamond coating to enhance the processing effect, as previously mentioned.

[0086] Figure 5 shows a cross-sectional view of the apparatus (50) in Figure 4. In this embodiment, the surface (34) of the acousto-optic modulator (10) facing the processing space (102) is formed as an external cycloid similar to the amplification structure (41). Although not bound by theory, it is assumed that by forming the side wall of the processing chamber, i.e., the surface (34) of the acousto-optic modulator (10), in a parabolic shape, acoustic waves can be effectively dispersed and reflected within the processing chamber. This makes it possible to enhance the processing effect.

[0087] Figure 6 shows a longitudinal cross-section of device (100) disclosed in International Publication Application Brochure No. 2012 / 028687, using the acousto-optic modulator disclosed herein. The device (100) for processing a medium (90), specifically air (91), comprises at least one apparatus (50) consisting of an acousto-optic modulator (10) and an electrode (40) within a processing chamber (101) defining a lumen (102), an inlet (103) in fluid communication with a first opening adjacent to the lumen (102) and a first end of the processing chamber (101), and an outlet (104) in fluid communication with a second opening adjacent to the lumen (102) and a second end of the processing chamber (101). The device further comprises a flow path (a) through the lumen (102) between the inlet (103) and the outlet (104).

[0088] Before entering the processing chamber (101), the gaseous or liquid medium (90) to be processed is transported into the plasma generating device (60) by external means not shown in this schematic diagram. However, the transport means may include, for example, one or more ventilation devices. The plasma generating device (60) may be a plasma chamber and preferably comprises a generator for generating electromagnetic radiation having a frequency in the microwave range.

[0089] The medium (90) enters the plasma generating device (60) through the plasma device inlet (61). Inside the plasma generating device (60), plasma (1) is generated in the medium (90), i.e., the air (91) is converted into plasma (1). The plasma (1) may exhibit 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 transported through the plasma device outlet (62) to a dielectric structure (63) which may be formed as a tube with a circular, rectangular, or elliptical cross-section. Specifically, such a structure can be formed with any cross-section. The tube is more preferably silica-containing or coated with silica. Such a molten silica tube (63) allows the plasma (1) formed in the plasma generating device (60) to be transported toward the processing chamber inlet (103) and processing chamber (101), respectively. This has the effect of accelerating at least some of the electrons in the plasma (1). The fused silica tube (63) has a tapered cross-section in the direction of medium flow (a), which means that the flow cross-section of the tube decreases in the direction of medium flow in at least one section of the tube. This is used to generate turbulence in the medium flow and within the plasma that contributes to the "mixing" of plasma (1). Thus, a synergistic effect can be achieved in sustaining plasma (1) over longer lengths and modifying plasma (1), thereby extending the reaction time between plasma (1) and medium (90). Although not bound by theory, it is also assumed that at least some of the electrons in the plasma are accelerated to higher speeds by surface waves within the dielectric structure (63), which also leads to improved processing.

[0090] In the processing chamber (101), the acousto-optic modulator (10) is positioned on the inner wall (105) of the processing chamber (101), and the volume (102), i.e., lumen (102), between the acousto-optic modulators (10) comprises a plurality of electrodes (40). The electrodes (40) are preferably covered with a complete diamond coating. A voltage of 4 to 17 kV is applied between the electrodes (40) by a power supply (not shown). Preferably, the voltage applied between the electrodes (40) is 8 to 12 kV. This has the effect of supporting plasma generation and preserving the plasma (1) present in the processing chamber (101). Therefore, the processing chamber (101) is expected to increase the interaction duration between the plasma (1) and the medium (90), thereby improving the processing effect and increasing the energy efficiency of the device (100).

[0091] A further advantage of the processing chamber (101) disclosed herein lies in the amplification of the number of photons, i.e., the number of photon species in the plasma, during the intended operation of the device (100). In other words, the processing chamber (101) is filled with plasma (1) that interacts with contaminants such as airborne microorganisms or chemical toxins, thus reducing the amount of such contaminants in the plasma (1). Consequently, the amount of contaminants contained in the plasma (1) exiting the processing chamber outlet (104) is reduced. Specifically, the device (100) described herein enables continuous processing of the medium (90) flowing through the processing chamber (101). Preferably, the inner wall (105) of the processing chamber (101) is provided with a diamond coating.

[0092] In this embodiment, the processing chamber (101) has, starting from the inlet (103) of the processing chamber and extending in the flow direction (a) of the medium (90), a first compartment having a substantially curved inner wall (105) and a second compartment having a flat surface formed by the surface (34) facing the lumen of the acousto-optic element of the acousto-optic modulator (10). The processing chamber (101) further comprises an amplification structure (41) in the form of an outer cycloid and a cylindrical structure (not shown) disposed within the volume surrounded by the amplification structure (41). The amplification structure (41) and the cylindrical structure are each characterized by a diamond coating.

[0093] In one preferred embodiment, the device (100) disclosed herein is configured to process a gaseous medium (91) and further comprises means for introducing a liquid (92) into a gaseous flow (not shown) to be processed.

[0094] A method for preparing an acousto-optic modulator disclosed herein is described below. The method for preparing an acousto-optic modulator includes the steps of: i) providing a mold comprising a first electrode and a second electrode, wherein the electrodes are spaced apart and each defines one wall of the mold; ii) optionally providing two contact elements, one on each side of the electrodes and facing each other; iii) connecting the electrodes to a voltage source; iv) providing a first dielectric in a molten state; v) filling the mold with the molten first dielectric; vi) applying a DC voltage to the two electrodes; vii) maintaining the voltage while the first dielectric is cooled, at least until the molten first dielectric is completely solidified; viiii) providing a dielectric textile, the textile comprising a double periodic structure; and ix) impregnating the textile with a dielectric having a refractive index different from that of the textile dielectric.

[0095] Electrets attract charged dust particles and various ions in open air, causing them to rapidly lose their charge. Therefore, they must be stored in a well-shielded state, for example, by covering them with aluminum foil.

[0096] Therefore, in a piezoelectric transducer, it is preferable that the dielectric is covered to the greatest extent possible by the electrodes, and that the contact between the dielectric and the electrodes is as large as possible.

[0097] Preferably, the electret is manufactured in a mold that will later form part of a device comprising an acousto-optic modulator.

[0098] By directly manufacturing the electret, i.e., the first dielectric after polarization in an electric field, within a mold that essentially contains the desired size of the final piezoelectric transducer, the electret does not need to be separated from the electrodes after its manufacture, thereby allowing the electret's charging properties to be maintained particularly well.

[0099] Alternatively, the molten first dielectric material may be poured into a mold located on a piece of aluminum foil placed on an insulated metal electrode. A second piece of aluminum foil is placed on top of the mold containing the molten material, and a cover electrode is placed on the foil.

[0100] After filling the mold with molten material, a high voltage is applied between the two electrodes, and the first dielectric is cooled under the influence of the applied voltage for about one hour until the first dielectric is completely solidified. The voltage is then turned off, and the electret thus obtained may be removed from the mold if necessary.

[0101] Preferably, the connection between the provided textile having a double periodic structure and the piezoelectric transducer is established in the impregnation step.

[0102] For example, one could place a glass fiber knit having approximately the same size as the contact surface of the piezoelectric transducer to be covered by the acousto-optic element on the contact surface, and impregnate the glass fiber knit with optical silicone before and / or after this.

[0103] If necessary, the glass fiber knit may also be fixed to a portion or the entire contact surface of the piezoelectric transducer before the impregnation step, for example, using assembly silicone.

[0104] This has the advantage, for example, that the shape of the piezoelectric transducer is not flat, or that the acousto-optic modulator is manufactured at different stations where semi-finished products must be transported between them, or that the geometric shape of the acousto-optic modulator requires the textile to be held against gravity, allowing the textile to be quickly and securely fixed in the desired shape. In this case, the actual impregnation of the glass fiber knit with an additional dielectric, such as optical silicone, is carried out in a later stage.

[0105] In one preferred embodiment, Raman scattering crystals, such as diamond nanoparticles, are added to a dielectric material used for impregnation of the textile. In this case, it is desirable that these particles be incorporated into the dielectric, such as optical silicone, before the impregnation step in order to achieve a uniform colloidal dispersion of the Raman scattering crystals within the dielectric.

[0106] Depending on the dielectric used for textile impregnation, it is preferable to crosslink the dielectric to achieve higher mechanical strength of the acousto-optic element and / or improved adhesion between the dielectric and the textile. Crosslinking can be carried out, for example, by ultraviolet irradiation, in which case the dielectric resin used for impregnation preferably contains a photoinitiator, and / or the textile is treated with a photoinitiator-containing compound prior to impregnation.

Claims

1. Acousto-optic modulator (10), wherein the acousto-optic modulator is A piezoelectric transducer (20) having a first electrode (21), a second electrode (22), and a dielectric (23) disposed between the electrodes (21, 22) in contact with the electrodes (21, 22), The acousto-optic element (30) comprises at least two further dielectrics (31, 32) having different refractive indices, Acousto-optic modulator (10), wherein the piezoelectric transducer (20) and the acousto-optic element (30) are stacked together, and at least one of the further dielectrics (31, 32) of the acousto-optic element (30) is a dielectric textile having a double periodic structure.

2. The acousto-optic modulator (10) according to claim 1, wherein the first (21) and / or second electrode (21) material is selected from metal, activated carbon, graphene, and ionic polymer.

3. Acousto-optic modulator (10) according to claim 1 or 2, wherein the dielectric (23) of the piezoelectric transducer (20) comprises at least one natural wax selected from the group consisting of carnauba, rosin, sugarcane, wood rosin glycerol ester, lanolin, shellac, animal fat, montane, ozokerite, whale wax, beeswax, auriculi, lacquer, beyberry, candelilla, Chinese wax, Chinese wax, and combinations thereof.

4. The dielectric (23) of the piezoelectric transducer (20) is ZnO, LiNb ３ , LiTaO ３ SiO ２ , quartz, TiO ２ , Si, SiN, AlN, GaN and SrTiO ３ An acoustic-optic modulator (10) according to claim 1 or 2, selected from the group comprising the above.

5. The acousto-optic modulator (10) according to any one of claims 1 to 4, wherein the piezoelectric transducer (20) further comprises two contact elements (24, 25) configured to ensure contact between the dielectric (23) and the electrodes (21, 22), and at least one of the contact elements (24, 25) comprises a dielectric textile.

6. The acousto-optic modulator (10) according to any one of claims 1 to 5, wherein the acousto-optic element (30) comprises a glass fiber knit impregnated with silicone resin.

7. The acousto-optic modulator (10) according to claim 6, wherein the silicone resin comprises at least one type of Raman scattering crystal (33).

8. The acoustic-optic modulator (10) according to claim 7, wherein the content of the Raman scattering crystal (33) in the silicone resin is 0.1 to 2 weight percent, and / or the size of the Raman scattering crystal (33) is 4 to 1000 nm.

9. The surface (34) of the acoustic-optic element (30) is made by applying a plasma containing oxygen and / or nitrogen to the silicone resin on the surface, thereby SiO ２ and / or SiN ｘ Acousto-optic modulator (10) according to any one of claims 6 to 8, configured to form a plasma mirror including

10. The acousto-optic modulator (10) according to any one of claims 1 to 9, wherein the total thickness of the laminate consisting of the piezoelectric transducer (20) and the acousto-optic element (30) is 4 to 80 mm.

11. An apparatus (50) comprising at least one acousto-optic modulator (10) and at least one electrode (40) according to any one of claims 1 to 10, wherein a space is formed between the surface of the acousto-optic modulator (10) and the electrode (40) into which a medium (90) can be introduced, and the electrode (40) includes at least one partial coating of a Raman scattering crystal (33).

12. A device (100) for processing a medium (90), wherein the device (100) comprises at least one apparatus (50) according to claim 11, the device (100) further comprising: a processing chamber (101) defining a lumen (102); an inlet (103) having a first opening that is in fluid communication with the lumen (102) and is adjacent to a first end of the processing chamber (101); an outlet (104) having a second opening that is in fluid communication with the lumen (102) and is adjacent to a second end of the processing chamber (101); and a flow path (a) between the inlet (103) and the outlet (104) that passes through the lumen (102).

13. The acousto-optic modulator (10) is positioned on the inner wall (105) of the processing chamber (101), and during the intended operation of the device (100), the lumens are filled with light to enable continuous processing of the medium (90) flowing through the processing chamber (101), as described in claim 12.

14. The device (100) according to claim 12 or 13, wherein the device (100) is configured to process a gaseous medium (91), and the device (100) further comprises means for introducing a liquid (92) into a gaseous flow to be processed.

15. A method for using the acoustic-optic modulator (10) according to any one of claims 1 to 11 for processing a medium (90).

16. A method of using the acousto-optic modulator (10) according to any one of claims 1 to 11 for shortening the duration of an optical pulse and / or increasing the energy of photons incident on the acousto-optic element (30).

17. A method for using the acoustic-optic modulator (10) according to any one of claims 1 to 11 for synthesizing organic molecules.

18. A method of using the acoustic-optic modulator (10) according to any one of claims 1 to 11 for producing hydrogen from water, alcohol and / or hydrocarbons.

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