RU2782978C9 - High-frequency optical switch and its manufacturing methods - Google Patents

Abstract

FIELD: optics.

SUBSTANCE: invention relates to the field of optical switches. An optical modulator contains optically transmitting substrate made with the possibility of distribution of electromagnetic radiation through it, and a metamaterial structure optically connected to the specified substrate. The metamaterial structure contains at least one layer of metamaterial particles, optically connected to at least some part of the specified optically transmitting substrate, and at least one nano-mesh layer made of at least one electroconductive material placed above at least some part of one metamaterial layer. At least one nano-mesh layer is made with the possibility of discharge of electrons to the specified at least one metamaterial layer, which is made with the possibility of transition from an optically non-transparent state to an optically transparent state, when receiving discharged electrons, while at least partially changing electromagnetic radiation passing through substrate.

EFFECT: invention provides optical modulation of long waves in a terahertz range.

21 cl, 10 dwg

Description

FIELD OF TECHNOLOGY

[001] The present invention generally relates to the field of optical switches suitable for use for high frequency modulation of light waves.

BACKGROUND OF THE INVENTION

[002] In data services, there is an ever-increasing demand for bandwidth required to meet the rapidly growing needs associated mainly with the widespread use of smartphones, social networks, video streaming and Big Data. The 10Gb/s technology currently widely used in data centers has reached its peak and larger data links are now required to handle the huge volumes of data transferred over communication networks. Indeed, service providers are moving to higher bit rate equipment to increase throughput to the 40 Gbps and 100 Gbps bands per wavelength.

[003] The International Telecommunication Union (ITU) divides the corresponding 1530-1565 nm electromagnetic microwave spectrum band (in which optical fibers show the least loss, also known as C-band) into fixed 50 GHz spectrum intervals. However, this channel diversity scheme is probably not suitable for transmission rates greater than 100 Gbps. Thus, there is a need in the art for a more flexible grid paradigm capable of meeting future throughput requirements.

[004] In fact, high data rate signals are becoming increasingly difficult to transmit over long distances with high spectral efficiency, even if a fairly wide spectrum is available. Therefore, it is advantageous for the transceivers to adapt to the actual network conditions and data rate for each given traffic request in order to maximize spectral efficiency. In addition to the need to improve spectral efficiency, large content providers, newly built data centers, and growing peering relationships between providers contribute to the inaccuracy and heterogeneity of requests in the network. Thus, there is a need for flexible and adaptive networks equipped with flexible transceivers and network elements that can adapt to the actual ever-increasing data traffic needs.

[005] It is recognized that fast switching and modulation are major barriers to increased bandwidth communication at rates greater than 100 Gb/s and in terahertz. Barriers and limitations for ultra-fast communication can be attributed to the RF, optical, switching and terahertz limitations associated with the network infrastructure currently in use, as explained below:

• RF limitations (microwave spectrum) are mainly due to the difficulty of manufacturing electronic devices capable of operating in frequency ranges well above a few hundred gigahertz. This complexity is partly due to the inherent need for very short carrier transfer times in the active regions of semiconductors, and is also a consequence of the low power generated by devices that must have small active regions to minimize their capacitance.

• Optical limitations are encountered because interband diode lasers are primarily designed to operate at visible and near-IR frequencies. However, it appears that the generation of light signals by radiative recombination of conduction band electrons with holes in the valence band through the band gaps of active semiconductor materials cannot simply be extended to the mid-IR or long wavelength ranges, since suitable narrow band gap semiconductors are not available.

• There are also limitations on switching, since controlling the transmission of light through a material, for example, by means of electric fields, is not suitable for long wavelengths, for example, in or near the terahertz range of the light spectrum, because the switching contrast between ON/OFF states, which can be achieved with solid-state electronic equipment, too weak and slow.

• The terahertz limitation is due to the lack of powerful sources of terahertz frequencies with good resolution.

[006] Some solutions proposed in the patent literature are briefly described below.

[007] European Patent Publication No. 2,876,824 describes a scheme for transmitting data on at least one carrier wave in the terahertz range. The transmission circuit comprises a transmitter, a receiver and an optical system for transmitting light beams. The transmitting device and the receiving means are adapted for wireless data transmission by means of a wave carrier modulated in the terahertz range of the transmitter. The carrier wave is generated by mixing the difference frequencies of two light beams from one or two light sources.

[008] The methods and apparatuses described in US Pat. No. 8,111,722 rely on optical resonators made from non-linear optical materials and non-linear wave mixing to generate RF or microwave oscillations and optical comb signals.

[009] U.S. Patent No. 8,159,736 describes photonic devices and methods based on tunable single sideband modulation (SSB) in whispering gallery resonators formed from electro-optical materials for coupling between whispering gallery modes of different polarizations.

[0010] The optical modulation system described in US Pat. optical signal at the operating wavelength in response to an external stimulus applied to the metamaterial structure. The external stimulus source is connected to the metamaterial structure and is configured to change the metamaterial structure between its permeable and non-permeable states by applying selected stimulus pulses to the metamaterial structure. The optical modulation system processes the input optical signal to output a modulated optical signal that modulates according to selected pulses applied to the metamaterial structure.

[0011] The foregoing description represents various techniques that may be associated with various aspects of the present disclosure and are intended to facilitate understanding of those aspects. Note that reference to any prior art referred to in this application is not an acknowledgment or suggestion that the prior art is part of basic common knowledge in any jurisdiction or that it is to be expected to be understood, regarded as relevant and/or combined with other analogues by a person skilled in the art.

GENERAL DESCRIPTION

[0012] The subject matter disclosed herein relates to the provision of methods and implementations for optical modulation of long waves in and/or near the terahertz range of the light spectrum to achieve very high transmission rates (100 Gb/s and higher, 400 Gb/s and in bands with data rates in terahertz). The embodiments disclosed herein are suitable for implementing optical modulators in solid state/chip devices capable of operating at room temperature. These implementations can provide the flexibility and data rates needed for scalable adaptive networks and thus attractive for use in new data centers currently built, for example, using flattened (east-west) topologies.

[0013] Responsive data centers can be constructed from block-like network infrastructure elements using virtual blocks that can be easily reconfigured. Moving to a physical network using blocks that can be easily scaled means the network can adapt without having to reconfigure the entire backplane. The combination of adaptive transceivers, a flexible mesh, and intelligent client nodes provides a new "adaptive" network paradigm that allows service providers to meet growing network demands without frequent redesign.

[0014] 100 Gb/s transmission systems have been commercialized in recent years, and since they are compatible with the 50 GHz ITU mesh/channel spacing already deployed, there has been no need to change the mesh. Both the telecommunications industry and the data communications industry are currently considering standard data rates above 100Gbps, with a lot of focus on 400Gbps. Unfortunately, the spectral width occupied by 400 Gbit/s in standard modulation formats is too wide to fit into the ITU 50 GHz grid, and its forced fitting to a higher spectral efficiency modulation format allows only short transmission distances. The fixed mesh does not support 400 Gbps and 1 Tbps in standard modulation formats because they overlap at least one 50 GHz mesh boundary. Thus, it is understood that the embodiments described herein are useful for data center implementations designed to meet the continuing increase in bandwidth requirements.

[0015] The embodiments described herein use an active metamaterial coupled to waveguides to create high quality optical switches, modulators, and/or filters capable of operating at terahertz data rates. In some embodiments, metamaterials are used to implement an efficient thin film terahertz switch that can enable terahertz communication and signal processing applications. Such a device is essential for filtering, switching and modulating terahertz signals. Until now, switching of terahertz radiation using thin film devices has been difficult due to the fact that terahertz electromagnetic wavelengths exceed the 300 micrometer range and thus do not significantly interact with structures much smaller than this wavelength. The use of metamaterials will help overcome this problem.

[0016] The terms waveguide, optical waveguide, or waveline are used herein to refer to media and/or elements suitable for use in transmitting electromagnetic radiation, such as (but not limited to) optical waveguides, optical fibers, air, which are used in optical data transmission. Metamaterials are artificially structured materials made by assembling various, often nano-sized objects to replace the atoms and molecules of conventional material, and engineered to exhibit properties that their base materials do not naturally exhibit. The metamaterials used in the embodiments herein have electromagnetic properties that are generally very different from those found in naturally occurring or chemically synthesized substances. The metamaterials used in some embodiments are designed to control the development of negative refraction.

[0017] The metamaterials used in some of the embodiments described herein have optical microstructures configured to interact with electromagnetic radiation passing through them. For example (and without limitation), such optical microstructures can be created using metal oxide materials such as VO2, V2O3, WO3, Ti2O3, NiS2-ySey, LaCoO3, PrNiO3, Cd2Os2O7, NdNiO3, Tl2Ru2O7, NiS, BaCo1-yNiyS2 (where y≤1), Ca1-ySryVO3 (where y≤1), PrRu4P12, BaVS3, EuB6, Fe3O4, La1-yCayMnO3 (where y≤1), La2-2Sr1+2Mn2O7 (where y≤1), Ti4O7, La2NiO4 , mixed oxides of the manganite type RExAE1-xMnO3 (where RE is a rare earth metal such as lanthanum or praseodymium, AE is an alkaline earth metal such as calcium, and x≤1), intermetallic compounds (such as NiAl), polymers such as azobenzene -containing polydiacetylenes, polyvinylidene fluoride, polyvinyl acetate, polyvinylphenylene, polystyrenesulfonate, polyanilines (e.g. polyanilines blended into synthetic opal nanostructures) and nanostructured polymers such as diblock copolymers (e.g. poly[styrene-b-isoprene] or PS-b-PI) and triblock (e.g. pol coil core copolymer y[poly(N-isopropylacrylamide)-b-polyfluorene-b-poly(N-isopropylacrylamide)]).

[0018] Such metamaterials can be used to create ultra-small and ultra-fast optical switches made from vanadium oxide (VO2). The ability of such devices to switch in the terahertz frequency ranges is much faster than similar switching devices tuned to operate at gigahertz frequencies. The use of VO2 metamaterials to create optical switches is particularly attractive because it can be switched at terahertz speeds between a transmissive (insulator) and a non-transmissive (conductor) state, inducing an electrical charge or field that can be used to create transistor-type devices.

[0019] The metamaterial used in some embodiments was made from VO2 nanoparticles that were deposited on an optically transparent substrate (glass) and coated with a "nano-mesh" of miniature gold nanoparticles. When this layered structure is irradiated with electromagnetic pulses from an ultrafast THz source (e.g., any type of THz signal generator, such as (but not limited to) laser sources, any device based on a THz emitting crystal, or a frequency multiplier), the hot electrons discharged from the gold nanogrid into a layer of VO2 nanoparticles, change its phase from optically opaque (metallic) to optically transparent (semiconductor) in a time within the picosecond (ps, 10 ^-12 seconds) time domain. The implementations described herein exploit this property of such metamaterials to controllably change between optically opaque and optically transparent states within the picosecond time domain to implement optical switches for communications applications.

[0020] One aspect of the subject matter disclosed herein relates to an optical switch used for data rates in the terahertz range. In some embodiments, the device comprises an optically transmissive substrate configured to propagate electromagnetic radiation through it, and a metamaterial structure optically coupled to the substrate. The metamaterial structure contains at least one layer of metamaterial particles optically bonded to at least some part of the optically transmissive substrate, and at least one nanogrid layer made of at least one electrically conductive material placed at least over some part of at least one layer of metamaterial. At least one nanogrid layer is configured to discharge electrons into at least one metamaterial layer sensitive to electromagnetic or electrical signals applied to the metamaterial structure, and said at least one metamaterial layer is configured to transition from an optically opaque state to an optically transparent one a state upon receiving discharged electrons with a change at least in part of the electromagnetic radiation passing through the substrate.

[0021] In some cases, the optically transmissive substrate is located in at least some part of the optical fiber. Alternatively, the optically transmissive substrate is at least some portion of an optical WGM resonator, such as a PANDA resonator. In yet another alternative, the optically transmissive substrate is a thin film.

[0022] In some embodiments, the substrate has a thickness of about 0.1 to 1 nanometer.

[0023] Optionally, but in some embodiments, at least one metamaterial layer contains vanadium oxide. At least one metamaterial layer may be configured to exhibit negative refraction upon receiving discharged electrons.
In some possible embodiments, the device comprises metal gratings formed on a metamaterial structure.

[0024] The thickness of at least one layer of metamaterial particles can typically be about 0.1-1 nm. In some embodiments, the particle size of at least one metamaterial layer is from about 1 to 100 nanometers.

[0025] Optionally, but in some embodiments, it is preferable that at least one layer of the nanogrid contains gold. The thickness of at least one layer of the nanogrid can typically be from about 0.1 to 1 nanometer. In some embodiments, the particle sizes of the nanogrid layer are from about 20 to 100 nanometers. The size/diameter of the pores of the nanogrid layer is in some embodiments from 0.1 to 1 nanometer.

[0026] The optical switch may have a geometric size of approximately 100 to 500 nanometers. In some embodiments, the electromagnetic or electrical signals applied to the metamaterial structure are in the radio, microwave, or terahertz frequency ranges (eg, in the range of 100 MHz to 40 THz).

[0027] According to another aspect, the subject matter disclosed herein relates to an optical modulator usable for data rates in the terahertz range. The modulator may comprise an optical switching device as described above or below, an input waveline configured to introduce input electromagnetic radiation into the optical switch, and an output waveline configured to transmit an output electromagnetic radiation at least partially modified by the optical switching device.

[0028] Another optical modulator assembly usable for data rates in the terahertz range can be implemented using an input waveline configured to input electromagnetic radiation into the optical modulator assembly; an optical splitter configured to receive input electromagnetic radiation from the input waveline, the first and second wavelines optically coupled to the optical splitter for receiving portions of the electromagnetic radiation from the input waveline, thus divided; at least one optical switch, as described above or below, optically connected to a respective core (core) of at least one of the first and second wave lines; and an optical adder optically coupled to the first and second wave lines to combine electromagnetic radiation received by them from the optical splitter and at least partially modified by at least one optical switch. The optical modulator may include an output waveline configured to receive electromagnetic radiation combined by an optical adder.

[0029] The optical modulator may include first and second optical switches respectively associated with the cores of the first and second wavelines. Optionally, but in some embodiments, it is preferable that at least one layer of the metamaterial contains vanadium oxide. In some embodiments, at least one metamaterial layer may be configured to exhibit negative refraction upon receiving discharged electrons.

[0030] In some embodiments, the modulator comprises metal gratings formed on a metamaterial structure.

[0031] According to another aspect, an object of the present invention relates to an optical combiner device for combining two or more electromagnetic data carriers. The device in the form of an adder contains at least one modulating WGM resonator having a metamaterial structure coating over the inner wall, at least two input wave lines optically coupled to at least one modulating WGM resonator for introducing at least two corresponding electromagnetic data carriers, and at least one output waveline optically coupled to said at least one WGM resonator to output electromagnetic radiation trapped within the modulating WGM resonator and at least partially combine at least two electromagnetic data carriers.

[0032] The structure of the metamaterial in some implementations contains vanadium oxide, for example, a layer of nanoparticles, as described here. The structure of the metamaterial may contain gold, for example, a layer of gold nanogrid applied over a layer of vanadium oxide, as described here.

[0033] In some embodiments, the optical combiner comprises at least one auxiliary WGM resonator having a metamaterial structure coating over an inner wall and optically coupled to said WGM resonator. The at least one auxiliary WGM resonator may be configured to generate electromagnetic radiation trapped within the at least one WGM resonator in a predetermined manner.

[0034] The optical combiner may include gratings formed on the metamaterial structure of at least one WGM resonator. Optionally, at least one of the WGM resonators may be an ellipsoidal resonator.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to understand the invention and see how it can be put into practice, embodiments will be described by non-limiting examples with reference to the accompanying drawings. The features shown in the drawings illustrate only some of the embodiments of the invention, unless otherwise indicated. In the drawings, like reference numerals are used to designate respective parts in which:

[0036] FIG. 1A-1C schematically illustrate the operation of optical switches according to some possible implementations: FIG. 1A shows an optical switch prepared by depositing a metamaterial onto a thin film, FIG. 1B shows a possible implementation of an optical switch, and FIG. 1C shows time plots of input and output wave interaction with an optical switch;

[0037] FIG. 2 schematically illustrates an optical switch in accordance with some possible implementations;

[0038] FIG. 3 schematically illustrates a possible implementation of an optical modulator according to some possible embodiments;

[0039] FIG. 4A and 4B schematically illustrate optical wave modulators using whispering gallery mode (WGM) resonators: FIG. 4A shows a possible implementation of an optical wave modulator using a ring resonator; FIG. 4B illustrates a possible implementation of an optical modulator using a plurality of optically coupled WGM resonators and demonstrates the proximity needed to facilitate crosstalk/signal combining for WGM modulation;

[0040] FIG. 5A-5C are examples of data transmission systems using optical wave modulators based on WGM resonators to combine data carriers of different frequencies.

DETAILED DESCRIPTION OF IMPLEMENTATION OPTIONS

[0041] One or more specific embodiments of the present disclosure will be described below with reference to the drawings, which are to be considered in all respects only as illustrative and not restrictive in any way. In an attempt to provide a brief description of these embodiments, not all features of the actual implementation are described. The elements shown in the drawings are not necessarily represented in the correct scale or proportions, which is not critical. Instead, emphasis is placed on clearly illustrating the principles of the invention so that those skilled in the art can create and use the optical switches/modulators described herein after understanding their structure and operation. This invention may be embodied in other specific forms and embodiments without deviating from the essential features described herein.

[0042] This document describes an optical switch and modulator capable of operating in high frequency bands, in and near the terahertz frequency range. The devices described use a metamaterial capable of controlled changes in its optical properties and thereby changing the path of electromagnetic radiation passing through a waveguide medium (eg, a fiber optic core) optically coupled to it. This is achieved in some embodiments by applying a metamaterial to a portion of the waveguide medium, such as an optical fiber, to optically couple the metamaterial to the waveguide medium (core) and allow the metamaterial to interact with electromagnetic radiation passing through it. For example, and without limitation, when used in an optical fiber, the metamaterial can be deposited at some predetermined length that corresponds to several wavelengths (λ) (e.g., at least 4λ) along the optical fiber, covering a certain angle/arc section, covering its entire circumference (360°).

[0043] In some embodiments, optical switches and/or modulators are combined into whispering gallery mode (WGM) optical cavity assemblies to modulate light introduced into the optical cavity by electrical/optical signals applied to the metamaterial. This can be achieved by placing a metamaterial on a portion of the WGM resonator to optically couple the metamaterial to the waveguide medium/resonator core and allow the metamaterial to interact with the electromagnetic radiation trapped inside the resonator. For example, and without limitation, if the WGM resonator is an annular/elliptical/torus resonator type, the metamaterial can be deposited at some predetermined length of at least 4 wavelengths along the WGM resonator, covering a defined angle/arc section encompassing its entire circle (360°). However, it should be noted that embodiments of the present application can equally use WGM resonators of various shapes, for example, in the form of three-dimensional spheres, three-dimensional ellipsoids, or three-dimensional toroidal structures with polygonal cross-sectional shapes (graphically obtained by rotating a polygon around the axis of symmetry of the toroid).

[0044] Optionally, but in some embodiments, the metamaterial is preferably made from nanoparticles of vanadium-based materials, such as (but not limited to) vanadium oxide (VO2) nanoparticles. However, it should be noted that other possible metamaterials may similarly be used to implement the optical switch and/or modulator described herein without departing from the boundaries and main directions of the present application.

[0045] The optical wave switches and/or modulators described herein can be configured to interoperate between nano and macro networks (THz ←→ GHz) and for biochemical assays, biomedical assays, chemical and molecular biology assays.

[0046] To review some of the features, process steps, and principles of the invention, the exemplary light modulation structures illustrated schematically in the figures are made from vanadium-based materials intended for use with coherent light, such as that produced by semiconductor laser devices. Metamaterial structures are shown as one implementation example that demonstrates a number of features, processes, and principles used to implement optical switches/modulators, but they are also useful for other applications and can be implemented in various ways. Therefore, this description will continue with reference to the examples presented, but bearing in mind that the invention set forth in the claims below can also be practiced in a variety of other ways, once the principles are understood from the descriptions, explanations, and drawings provided herein. All such variations, as well as any other modifications obvious to a person skilled in the art and useful in data communications applications, can be suitably used and fall within the scope of the present disclosure.

[0047] Investigation of the optical phase change of vanadium-based metamaterial nanoparticles such as VO2 coated with gold nanoparticles using a THz source does not answer whether this optical phase change can be obtained using electrons, for example, using a controlled electric field change. In the terahertz communication domain, devices should be sensitive to electrons and photons with the lowest possible energy and time costs for activation and recovery. The inventor of the present invention has found that the optical phase change of VO2 works well with electrons (i.e., can be controlled by an electric field) and that the injection of hot electrons from gold nanoparticles also causes a one-fifth to one-tenth conversion, since a lot of energy is required if the laser radiation is directed directly at the VO2 nanoparticles (the use of gold nanoparticles is 90% more efficient than direct laser irradiation of VO2 nanoparticles). Thus, it can be concluded that the optical switches described herein can be turned on and off using light sources and/or electron/electric field sources operating at data rates in the radio, microwave, and terahertz frequency bands.

[0048] FIG. 1A schematically shows an optical switching device 3 formed from a substrate 3f made in some embodiments as a thin film. The switching device 3 in this non-limiting example is made of a layer of nanoparticles 3m, having a thickness of about 0.1-1 nanometer, optically connected to at least some part of the substrate 3f (for example, by sputtering) and a nanogrid of gold and/or similar (electrically conductive) nanoparticles 3u, having a thickness of about 0.1 to 1 nanometer, deposited (for example, by sputtering) on at least some part of the metamaterial layer 3m.

[0049] The sizes of the 3m metamaterial nanoparticles can generally be in the range of 1 to 20 nanometers, in some embodiments from about 1 to 100 nanometers. The particle sizes of the gold nanomesh 3u can typically be about 20 to 100 nanometers, and its pore size 3p can typically be about 0.1 to 1 nanometer. The substrate 3f may be made from an optically transparent material, and in some embodiments it is implemented as a thin film made from materials that provide transparency when sintered (eg ceramics) and have a thickness of about 0.1 to 1 nm.

[0050] In some embodiments, the metamaterial layer 3m is made of VO2 nanoparticles, which can have various shapes. The geometric size of the optical switch 3 in some possible implementations is about a few hundred nanometers in diameter, optionally about 100-500 nanometers, which is much smaller than the geometric dimensions of optical switches previously available. Such a smaller terahertz switching optical switch (for example, based on vanadium oxide materials) can overcome some of the technical barriers to high-speed terahertz switching, offering a solution that can change storage, data transmission and telecommunication technologies.

[0051] FIG. 1B schematically illustrates the structure and operation of optical switch 10 in accordance with some possible implementations. In this non-limiting example, a thin layer of metamaterial 3m is deposited on a thin substrate (not shown) and at least partially covered with a gold nanogrid (not shown) capable of being irradiated by signals generated by signal source 8. The optical switch 10 includes, in some embodiments, optical gratings 11 formed by parallel metal lines deposited on at least some or all of the surface of the metamaterial 3m to improve non-linear processes on the surface (for example, for frequency conversion). The gratings 11 can be made by mechanical or chemical erosion.

[0052] The distance d between the metal gratings 11 can be configured for phase-matched input radiation 10a of different wavelengths to provide sensitive, phase-matched and coherent output radiation 10b. This distance d is usually set to be substantially less than the wavelength of the input radiation 10a (e.g., RF, microwave, or terahertz), for example, in some embodiments, d is about 10 micrometers, to thereby ensure that all input wavelengths of the input the radiations 10a pass through the optical switch 10 to obtain a coherent and phase-matched output radiation 10b.

[0053] Signals 8r (electromagnetic/radio frequency/microwave radiation or electrons/electric field) from the signal source 8 applied to the metamaterial 3m of the optical switch 10 cause hot electrons to be ejected from the gold particles of the nanogrid into the metamaterial layer 3m, causing the metamaterial 3m to go from opaque phase to transparent phase within a time interval less than a picosecond. The phase change of the metamaterial layer 3m can be used to modulate the input electromagnetic radiation 10a directed to one side of the device 10 to create a phase-shifted output 10b of the electromagnetic radiation on the other side of the device 10.

[0054] The signal source 8 may be physically connected to the optical switch 10, such as using a photomixer or frequency multiplier, or may be implemented as a signal source using a contactless port to supply input electromagnetic radiation 10a, such as a photomixer or frequency multiplier (t i.e. without physical contact with the switching device 10), configured to generate pulsed signals in the terahertz frequency range and/or near it, for example, ≥400 Gbit/s and up to 40 THz. FIG. 1C graphically illustrates the phase shift obtained between the input electromagnetic radiation 10a and the electromagnetic radiation 10b output from the optical switch 10, and exactly corresponds to the calculations shown by the dashed line 10c.

[0055] FIG. 2 schematically illustrates an optical switch 7 according to some possible implementations. The optical switch 7 contains: a waveguide substrate 7t, configured to transmit electromagnetic radiation (EMR) 9d generated by an EMR source 9 (for example, a laser radiation generator), a layer 7u of metamaterial nanoparticles optically coupled to at least some part of the transmitting substrate 7t , and a nanogrid layer 7v deposited at least over some part of the metamaterial layer 7u. The waveguide substrate 7t can be configured to transmit the EMP 9d along its length via total internal reflection, for example using a suitable optically transmissive material and/or sheath (not shown).

[0056] Modulating (light electromagnetic, radio frequency, microwave, terahertz or electric) signals 8r generated by the signal source 8 and applied to the nanogrid layer 7v are used to switch the metamaterial layer 7u between its optically opaque and transparent phases and, accordingly, affect the properties internal reflection of the waveguide substrate 7t between the optically reflective and non-reflective (or partially reflective) states, thereby modulating the input EMI 9d according to the applied modulating signals 8r.

[0057] In some embodiments, electromagnetic radiation sources and/or modulating signal sources 8 use the methods and/or implementations described and illustrated in International Publication No. WO 2007/132459 and/or in US Patent Application No. 9,964,442 of the same applicant, ref. which is given in this document. The modulated EMP generated by the devices described herein can be detected by known detectors such as (but not limited to) passive or active detectors.

[0058] In some embodiments, metamaterials configured to provide controlled negative refraction are used to modulate electromagnetic radiation. For example, in possible implementations, the metamaterial is optically coupled to some portion of the transmissive optical fiber core or optical resonator, whereby the phase of the light passing through it is shifted by applying modulating signals (8r) to a gold nanogrid deposited over at least some of the metamaterial. The requirements for such optical switches/modulators include high modulation efficiency, low modulating power (8r) e.g. life time.

[0059] FIG. 3 schematically illustrates an optical modulation device 17 in accordance with some possible implementations. The modulation device 17 comprises an input waveline 22a configured to input the input EMP 9d (Input A) into the modulator 17, an optical splitter 22p configured to split the input EMR 9d into first and second wave lines, 22f and 22s respectively, an optical modulator 30 , optically coupled to the second waveline 22s, and an optical combiner 22c configured to combine the EMR passing along the first and second wavelines 22f and 22s into an output waveline 22b (Output C). The optical modulator 30 is configured to controllably change the EMI passing through the second waveline 22s in response to the modulating signals (Input B) received from the signal source 8 and to introduce phase shifts into it in response. Thus, the EMPs from the first and second wavelines are combined either constructively or destructively by an optical adder 22c responsive to modulating signals from the signal source 8, thereby optically modulating the input EMP 9d. Optical modulator 30 may be implemented using any of the optical switches and/or modulators described above and below.

[0060] FIG. 4A schematically illustrates an optical modulator 20 using a WGM ring resonator 28. The ring resonator 28 is optically coupled to an input waveline 22a capable of introducing an input EMR into the resonator 28 and to an output waveline 22b configured to receive an output EMR from the resonator 28. EMR modulated by resonator 28. Ring resonator 28 contains a metamaterial structure 23 optically coupled to at least some portion of its optically transmissive core. The metamaterial structure 23 can be connected to predetermined angular/arc portions defined around the central axis/symmetry axis 28c of the resonator (given by the angle α) and/or around its circular axis 28r (given by the angle β). The structure 23 of the metamaterial can be optically coupled to the entire transverse circumference of the ring resonator 28 (α = 360°). The structure of the metamaterial can be optically connected to the entire circumference in the cross section of the ring resonator 28 (β = 360°).

[0061] The structure 23 of the metamaterial contains a layer 23v of nanoparticles of the metamaterial (for example, VO2) deposited on at least some part of the wall of the core of the ring resonator 28 (or on the entire) wall, and a gold nanogrid 23u deposited on at least some of the layer 23v metamaterial nanoparticles. Nanogrid 23u is configured to receive modulating (electromagnetic and/or electrical) signals from signal source 8 and to change metamaterial nanoparticle layer 23v in response between its optically transmissive and optically non-transmissive states to modulate EMR introduced into it by input wave line 22a.

[0062] FIG. 4B schematically shows an optical modulator arrangement 40 using a plurality of optically coupled WGM resonators 41, 42, 43 and 44, configured to bridge the wavelength gap between two input EMR data carriers, F1 and F2, of different frequencies (e.g., light and/or terahertz signals). The modulator 40 comprises respective input wavelines 45 and 46 configured to introduce EMR carriers, F1 and F2 respectively, into the main and/or modulating WGM resonator 41, for example, by proximity, i.e. optical coupling without physical contact with the WGM resonator 41. WGM resonator 41 is made in some embodiments of a dielectric material, the inner wall of which is coated with a metamaterial structure 23, that is, it contains a layer of metamaterial nanoparticles (for example, VO2) coated with an electrically conductive nanogrid (for example, made of gold).

[0063] The main WGM resonator 41 is configured to capture the modulated EMR carriers F1 and F2 propagating along the input lines 45 and 46 and couple their frequencies to each other as they resonate along the inner wall of the WGM resonator 41 coated with the metamaterial structure 23 , and outputs the EMR radiation through the output line 47 optically coupled to the main WGM resonator 41. The output EMR propagating along the output wave line 47 thus combines the modulated EMR carriers to provide the output EMR F1+F2. This is achieved in some embodiments by gratings configured to promote non-linear processes that have the effect of merging EMR through random surface charge and possible equilibrium local states on the surface. Thus, the elimination of crosstalk and/or the combination between EMR of significantly different wavelengths (for example, radio and terahertz) is simplified. Grids (eg, metal grids - not shown) can be placed on the metamaterial structure as shown in FIG. 1b.

[0064] Auxiliary WGM resonators 42, 43 and 44 may be made of a dielectric material, the inner wall of which is coated with a metamaterial structure 23. Auxiliary WGM resonators 42, 43 and 44 are optically coupled to the main WGM resonator (by proximity), but are sized to form a combined EMR trapped within the main/modulating WGM resonators 41 in a predetermined manner to introduce radiation patterns emissions to be used to demodulate the combined signal in a receiver (not shown) that receives the output EMP propagating along the output waveform 47, for example by adding (no information) patterns to the carrier spectral changes and the modulated information, this serves to prevent the occurrence of communication errors.

[0065] Thus, multiple EMP carriers having different frequencies (eg, radio, microwave, and/or terahertz) can be optically combined on a single EMP carrier and transmitted to a receiver. Although the WGM resonators 41, 42, 43 and 44 shown in this non-limiting example are ellipsoids, other configurations and shapes can be used in a similar manner. The dimensions of the main ellipsoidal WGM resonator 41 can typically be about 10-150 microns, and the dimensions of the auxiliary ellipsoidal WGM resonator 42, 43 and 44 can generally be smaller than the main/modulation ellipsoid 41 to prevent modulation.

[0066] FIG. 5A schematically shows an optical data communication system 33 using an optical modulator 17' configured to receive two modulating signals and combine them on an EMP carrier, in this specific and non-limiting example, a terahertz carrier, THz1, THz2,... Optical modulator 17 ' can be implemented using the optical modulator device (17) shown in FIG. 3A, or with the WGM cavity modulator implementation of FIG. 4A and/or 4B modified to optically modulate multiple EMP waves having different wavelengths, THz1, THz2, ....

[0067] The modified optical modulator 17' in this example comprises an optical modulation module 30 in each of the wavelines 22f and 22s for optically modulating the EMR input to each optical modulator 17' with two respective modulating signals to perform branched modulation such that each branch implements a separate data channel with its respective optical modulation module 30 . The system 33 comprises a first set 39 of optical modulators 17', each of which is configured to receive and modulate by phase shifting the respective EMP carrier, THz1, THz2, ..., with two modulating signals from a repeater 26. Repeater 26 is configured to generate two modulating signals for each optical modulator 17' in the first set 39 of the optical modulator.

[0068] A second set of 38 optical modulators is configured to modulate EMP from a light source (eg, a laser source) passing through the 36x waveline. Each optical modulator 17' in the second set 38 is configured to receive two respective modulated optical signals generated by the optical modulator 17' of the first set 39 for EMR modulation in waveline 36x. The modulated EMP generated by the second set of 38 optical modulators (also referred to as the complex signal) may be radiated by the antenna transmitter unit 36 configured to radiate the complex signal over the air interface. Tuner 37 can be used for efficient Shannon correlation to adapt the modulated signals to the bandwidth of the EMR carrier.

[0069] FIG. 5B schematically illustrates an optical data transmission system 35 comprising a plurality of optical modulator units 50 configured to mix two THz signals of different frequencies, each of said units configured to receive a respective specific band of input EMP 51 (e.g. from a light/laser source), directed by a focused prism and separated by a shifted prism to create several channels, and input EMR 52 (for example, from a light / laser source) from the adder unit 39 to integrate the signal and modulate it on the corresponding terahertz wave THz1, THz2, ... Chip units 50 optical modulators can be implemented using the WGM resonators 40 shown in FIG. 4B, configured to connect the EMI from two EMI data carriers and generate a corresponding terahertz EMI output combining the two EMI data carriers, as explained above.

[0070] FIG. 5C schematically shows another optical communication system 34 in which a respective optical modulator 17' is optically coupled to each optical modulator chip unit 50 of the system 35 shown in FIG. 5V. In this non-limiting example, an optical modulator 17' is used to combine the RF signals into an input EMI 51, which is then combined by an appropriate optical modulator chip unit 50 with an EMI input carrier 52 from combiner 39 to generate the corresponding THz channel.

[0071] As shown above and below, the optical modulation/switching devices of the present application provide modulation technologies that can operate according to the physical nature of their signal, and embodiments of optical modulators/switches can be used to eliminate crosstalk and facilitate combining widely separated lengths. waves, i.e. in radio frequency and terahertz ranges.

[0072] Optical radio and/or THz frequencies are only one category, including a wide range of new devices. In some implementations, whispering gallery mode (WGM) optical and THz cavities are used to modulate the input EMP. Understanding how these devices are made and used is important in assessing their performance and limitations. Therefore, this part of the description will introduce this class of cavity sensors (transmitter and receiver) and describe how these devices can be used for terahertz data transmission in general and for data centers in particular, as a convenient solution for fast communication.

[0073] Optical WGM resonators exhibit tunability and narrow resonant linewidth and achieve extraordinary optical property intensities that initially led to their use in some telecommunications implementations as a modulator device. Since then, they have become valuable tools for the study of nonlinear optical phenomena and quantum electrodynamic principles. In some possible embodiments, optical WGM resonators are used to implement optical communication modulators, as will be described below. These embodiments can be used (but not limited to) for biochemical assays, biomedical assays, chemical and molecular biological assays, as their extreme sensitivity in these areas can be used to develop analytical and diagnostic instruments.

[0074] WGM resonators get their name from the path that resonant light takes as it circulates in the cavity. This path is similar to that which the sound waves traveled along the curved wall of the circular room Lord Rayleigh studied. In these whispering galleries, two people facing the wall on opposite sides of the room can hear each other, even speaking in whispers. These people would not be able to hear each other if they stepped back towards the center of the room. This effect is caused by smooth, curved walls that guide sound waves around the perimeter of the room with great efficiency. Sound waves traveling to the listener in any other way are scattered or scattered along the way.

[0075] Optical WGM resonators are dielectric structures capable of capturing light along a perimeter path, similar to those that capture sound waves passing from one person to another in a whispering gallery. Although Mee and Debye described the resonant natural frequencies of dielectric spheres before Lord Rayleigh's work, the name was applied to this type of optical resonator much later.

[0076] The embodiments of the optical switches and/or modulators described herein can be used in data centers to provide the network scalability and adaptability needed for today's data network, such as cloud-managed applications and storage. A widely used metric to measure the energy efficiency of a data center is energy efficiency, or EE. This simple ratio is the total energy entering the data center divided by the energy used by the IT equipment.

[0077] Total energy consists of energy used by IT equipment and any overhead energy consumed by anything that is not considered a computing or data communication device (eg, cooling, lighting, etc.). The ideal EIE value is 1.0 for a hypothetical zero service energy situation. The average US data center has an EIE of 2.0, which means the equipment uses two watts of total energy (overhead + IT equipment) for every watt delivered to the IT equipment. The energy efficiency level of a modern data center is estimated to be around 1.2. Some major data center operators such as Microsoft and Yahoo! published EE forecasts for equipment under development; Google publishes quarterly actual performance metrics from operating data centers.

[0078] Energy efficiency is a key feature for some of the embodiments described here. The US Environmental Protection Agency has an Energy Star rating for stand-alone or large data centers. To qualify for an eco-label, a data center must be in the top quartile of the energy efficiency of all reported facilities. The European Union also has a similar initiative known as the EU Data Center Code of Conduct.

[0079] Often, the first step to limiting power usage in a data center is understanding how power is being used in the data center. There are several types of analysis to measure data center energy usage. Aspects measured include not only the energy used by the IT equipment itself, but also by data center equipment such as chillers and fans.

[0080] Energy is the largest recurring cost to a data center user. Energy and cooling analysis, also called thermal assessment, measures the relative temperatures in certain areas, as well as the ability of cooling systems to withstand certain ambient temperatures. Energy and cooling analysis can help identify hotspots, areas with excessive cooling that can handle higher energy density, equipment load breakpoint, raised floor strategy effectiveness, and optimal equipment placement (such as AC units) to balance temperatures throughout the processing center data. Cooling power density is a measure of the area that a center can cool at maximum load.

[0081] An energy efficiency analysis measures the energy consumption of an IT center and data center equipment. A typical energy efficiency analysis measures factors such as data center energy efficiency (EEI) against industry standards, identifies mechanical and electrical sources of inefficiency, and determines air management metrics.

[0082] In order to explore the capability of the optical switches and/or modulators described herein to transmit data at THz rates, the data communication systems described herein can be designed using multi-hop communication in which nodes in a network can communicate using two or more other nodes acting as transit nodes between the source node and the destination node of the terahertz communication with both passive and active switches. There are several advantages to using intermediate switches between transmitter and receiver at THz frequencies. As with any wireless communication system, the transmit power, and hence the power consumption, can be reduced by having multiple intermediate hops between transmitter and receiver. In addition, due to the unique distance dependent behavior of the available bandwidth, reducing the transmission distance results in the availability of much wider bandwidths and thus much higher transmission rates. It can also contribute to significant energy savings.

[0083] As noted above, the embodiments described herein can be used to develop new types of fast optical conductors capable of charge-coupling as opposed to conventional conduction.

[0084] Emerging wearable nanosensor networks provide many valuable applications in the biomedical and environmental fields. At the same time, the current state of communication technologies significantly limits the processing capabilities of promising nanomachines. Therefore, it is understood that all analysis of the collected data must be performed on the macro device. Therefore, the effective implementation of long-awaited applications of nanonetworks requires their seamless integration into existing network infrastructures, which leads to the concept of the Internet of nanothings. In embodiments of this application, interoperability between already deployed macronetworks and emerging nanonetworks has been previously clarified.

[0085] However, the solution to this problem is non-trivial, since existing macro wireless networks mainly use carrier-based electromagnetic communication, while nanomachines must rely on ultra-low-power pulse-based electromagnetic radiation or their own mobile objects as carriers. information. Thus, direct interaction between macro and nanonetworks is currently not feasible, which requires the use of special gateway nodes. Moreover, current nano-communications solutions need to be rapidly improved to enable large-scale networks to be built on existing communication layer technologies. To achieve this goal, it is necessary to solve many theoretical issues, ranging from the development of the correct modulation and coding technique to the reduction of noise and interference. The implementations described in this document provide the key to this area as well.

[0086] It should be noted that combining metamaterial-based switches/modulators (e.g. using VO2 particles to transition between opaque and transparent metamaterial states with a picosecond time range) with WGM resonators (e.g. PANDA ring resonator) can provide fast optical transmission implementations. data and adapt antennas for a range of applications in biology, chemistry, materials science, nanonetworks, etc.

[0087] As described above and shown in the respective drawings, this application presents optical switches and modulators for data rates in the terahertz range and methods for their manufacture. While specific embodiments of the invention have been described, it should be understood that the invention is not limited thereto, as modifications may be made by those skilled in the art, especially in light of the foregoing. As one skilled in the art will appreciate, the invention may be practiced in a variety of ways using more than one of the techniques described above without departing from the scope of the claims.

Claims (21)

1. Optical modulator suitable for use for data rates in the terahertz range, and the optical modulator contains: an input wave line configured to input electromagnetic radiation into the specified optical modulator, an optical splitter configured to receive input electromagnetic radiation from the specified input wave line, first and second wave lines optically coupled to said optical splitter for receiving portions of electromagnetic radiation from an input wave line so divided, at least one optical switching device optically coupled to a respective core of at least one of the first and second wave lines, and an optical combiner optically coupled to said first and second wave lines to combine the electromagnetic radiation received by them from the optical splitter and at least partially modified by said at least one optical switching device; wherein at least one optical switching device is suitable for use for data rates in the terahertz range, wherein the optical switching device comprises an optically transmissive substrate configured to propagate electromagnetic radiation through it, and a metamaterial structure optically connected to said substrate, wherein said the metamaterial structure contains at least one layer of metamaterial particles optically bonded to at least some part of said optically transmissive substrate, and at least one nanogrid layer made of at least one electrically conductive material placed at least over some part of said optically transmissive substrate. at least one metamaterial layer, wherein said at least one nanogrid layer is configured to discharge electrons into at least one metamaterial layer sensitive to electromagnetic or electric forces signals applied to the structure of the metamaterial, and said at least one layer of the metamaterial is capable of transitioning from an optically opaque state to an optically transparent one upon receiving discharged electrons with a change at least partially in the electromagnetic radiation passing through the substrate, and at the same time, the optically transmissive substrate has at least one of the following configurations: the optically transmissive substrate is at least some portion of the optical fiber; and the optically transmissive substrate is at least some portion of a whispering gallery mode (WGM) optical cavity. 2. Optical modulator according to claim 1, containing an output wave line configured to receive electromagnetic radiation combined by an optical adder. 3. Optical modulator according to any one of paragraphs. 1 and 2, comprising first and second optical switching devices respectively connected to the cores of the first and second wave lines. 4. The modulator according to any one of paragraphs. 1-3, in which at least one layer of the metamaterial contains vanadium oxide. 5. The modulator according to any one of paragraphs. 1-4, in which at least one metamaterial layer is configured to exhibit negative refraction upon receiving discharged electrons. 6. Modulator according to any one of paragraphs. 1-5 containing metal gratings formed on a metamaterial structure. 7. Modulator according to any one of paragraphs. 1-6, in which the thickness of at least one layer of metamaterial particles is about 0.1-1 nm. 8. Modulator according to any one of paragraphs. 1-7, in which the particle size of at least one metamaterial layer is from about 1 to 100 nanometers. 9. The modulator according to any one of paragraphs. 1-8, wherein said at least one layer of the nanogrid contains gold. 10. Modulator according to any one of paragraphs. 1-9, in which the thickness of at least one layer of the nanogrid is from about 0.1 to 1 nanometer. 11. The modulator according to any one of paragraphs. 1-10, in which the particle size of at least one layer of the nanogrid is from about 20 to 100 nanometers. 12. The modulator according to any one of paragraphs. 1-11, in which the pore size of at least one layer of the nanogrid is from about 0.1 to 1 nanometer. 13. The modulator according to any one of paragraphs. 1-12 having a geometric size of about 100 to 500 nm. 14. The modulator according to any one of paragraphs. 1-13, in which the electromagnetic or electrical signals applied to the metamaterial structure are in the radio, microwave or terahertz frequency range. 15. The modulator according to claim 14, wherein the electromagnetic or electrical signals applied to the metamaterial structure are in the range from 100 MHz to 40 THz. 16. An optical adder for combining two or more electromagnetic data carriers, said adder comprising: at least one whispering gallery mode (WGM) resonator having a metamaterial structure coating over an inner wall, at least two input wavelines optically coupled to said at least one WGM resonator for introducing into it, respectively, at least two electromagnetic data carriers, and at least one output wave line optically coupled to said at least one WGM resonator for outputting electromagnetic radiation trapped inside said at least one WGM resonator; and at least a partial combination of said at least two electromagnetic data carriers. 17. An optical combiner according to claim 16, wherein the metamaterial structure contains vanadium oxide. 18. Optical adder according to any one of paragraphs. 16 and 17, in which the metamaterial structure contains gold. 19. Optical adder according to any one of paragraphs. 16-18, containing at least one auxiliary WGM resonator having a metamaterial structure coating over the inner wall and optically coupled to said at least one WGM resonator, wherein said at least one auxiliary WGM resonator is configured to generate electromagnetic radiation captured inside said at least one WGM resonator in a predetermined manner. 20. Optical adder according to any one of paragraphs. 16-19, containing gratings formed on the metamaterial structure of at least one WGM resonator. 21. Optical adder according to any one of paragraphs. 19 and 20, wherein at least one of the WGM resonators is an ellipsoidal resonator.

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