Parametric devices with strontium titanate (STO) based nonlinear dielectrics

Abstract

Thin film and bulk strontium titanate (SrTiO3 or STO) can be used as a nonlinear dielectric medium in parametric devices including amplifiers, upconverters, downconverters, circulators, gyrators, isolators and tunable circuits. In these devices, STO is a versatile alternative to traditional Josephson junction (JJ) and high-kinetic inductance (KI) devices, and to electrooptic crystal devices including Pockels cells. STO-based parametric devices can operate over a wider range of temperatures (mK to tens of K), and frequencies (sub-GHz to hundreds of GHz), with little or substantially no power limitations. Examples include parametric amplifiers, microwave-to-optical upconverters and tunable microwave circuits.

Description

Docket No. P326921.WO.01PARAMETRIC DEVICES WITH STRONTIUM TITANATE(STO) BASED NONLINEAR DIELECTRICSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Application No. 63 / 778,970, filed 27 March 2025, entitled “Parametric Devices Using Nonlinear Dielectric Properties of SrTiO3,” which is incorporated by reference herein, in the entirety and for all purposes.FIELD

[0002] The present disclosure relates to nonlinear electronic devices. More specifically, the disclosure relates to parametric devices utilizing nonlinear dielectric media.BACKGROUND

[0003] Parametric devices, including parametric amplifiers and waveguides, are a ty pe of amplifier or oscillator that operates by varying a parameter (e.g., reactance) to achieve amplification or oscillation at a different frequency. Parametric devices can further include upconverters, downconverters, circulators, gyrators, isolators, and the like.

[0004] Traditional parametric devices can be made from Josephson junction (JJ) type devices, or using hybrid devices based on the Josephson junction, such as superconducting interference devices (SQUIDs), or alternatively with other, high-kinetic inductance (KI) materials. The dependence on superconducting effects imposes severe limitations on the performance of the parametric devices. These limitations can include limited operational frequency, limited operating temperature, and magnetic sensitivity. Therefore, there is a need for parametric device that can operate over a wide range of temperatures and frequencies with.SUMMARY

[0005] Parametric devices can be formed with a base conductor disposed on a substrate, and a layer of nonlinear dielectric disposed on the base conductor. The nonlinear dielectric can comprise strontium titanate (SrTiO3 or STO), or another dielectric with suitable properties, or any combination of such dielectric materials, as described herein. Alternatively, the nonlinear dielectric can be disposed directly on the substrate.

[0006] The substrate can be formed of any suitable substrate material including, but not limited to. silicon, sapphire, silicon-on-sapphire, silicon carbide (SiC), magnesium oxide (MgO), a silicon + silicon dioxide (SiO2) or thermal oxide / thermal barrier material, or any-1- 4923-4641 -7530\4combination thereof. The nonlinear dielectric can be provided as a bulk material or in thin film form, and an electrode layer can be disposed on the nonlinear dielectric; e.g., using a conducting material to define a circuit. One or more input ports or terminals can be provided for coupling the circuit with a signal, with one or more output ports or terminals for coupling the circuit with an output.

[0007] The nonlinear dielectric can be configured to modulate an operational parameter of the circuit (e.g., the reactance, or alternatively the impedance) via interaction with a pump wave, for example via resonant coupling with the circuit. The pump wave and signal are mixed via interaction with the nonlinear dielectric, and as a function of the modulated operating parameter, generating an idler wave. The output is generated based on energy transfer between the signal and idler wave.

[0008] The signal and output can include radio frequency (RF), millimeter wave (mm-wave) microwave, terahertz (THz), infrared (IR) or optical signals. The electrode can be configured as a waveguide adapted to sustain the signal, pump wave and idler wave, in either resonant or propagating modes.

[0009] The output can have the same frequency and phase as the signal, or a different frequency or phase; e.g., where the signal is upconverted or downconverted to generate the output. The parametric device can also include a photonic integrated waveguide, in order to upconvert or downconvert to or from terahertz, infrared, or optical frequencies. A filter can be coupled to the circuit for isolating the signal or output, or for non-reciprocal flow between the input and output terminals. Bias matching inputs can be configured to modulate the reactance or inductance at the input and output, for example based on direct current (DC) bias matching signals.

[0010] Methods for operating the parametric device are also provided, including receiving the signal via the input terminal; mixing the pump wave and signal, generating the idler wave, and producing the output via the output terminal (e.g., by energy transfer between the pump wave and signal, via the idler wave). The signal can be amplified, upconverted or downconverted.

[0011] Methods for manufacturing the parametric device include providing the substrate, disposing the base conductor on the substrate, and disposing the nonlinear dielectric (e.g., STO) on the base conductor. The electrode layer is disposed on the nonlinear dielectric to define the circuit. The substrate, base conductor and nonlinear dielectric can be annealed,and the electrode layer can be etched or otherwise microfabricated to define a waveguide configured to sustain the signal, the pump wave and the idler wave, in one or more resonant or propagating modes.

[0012] These examples can be adapted to provide a range of different parametric devices including, but not limited to, parametric amplifiers, upconverters, downconverters, circulators, gyrators, isolators and tunable circuits. These devices can operate over a wide range of temperatures (e.g., from mK to tens of K, or even up to room temperature), and at different frequencies including sub-GHz to hundreds of GHz, THz, and above, without substantial power limitations.

[0013] This description is provided for the purposes of illustration and explanation, using specific nomenclature to provide a thorough understanding of the examples that are described. It will be apparent to anyone skilled in the art that not all the specific details that are disclosed are required to practice the invention as claimed. The description is not exhaustive, and does not limit the claims to any of the examples that are disclosed, except as expressly cited in the claim language.

[0014] It will also be apparent to one of ordinary skill in the art, having read this application, that modifications and variations of these techniques are possible in view of the above teachings, w hile remaining consistent with the scope of the invention as claimed. While various applications have been described with reference to certain specific features, moreover, as adapted to particular problems and examples, other variations are also possible, without departing from the claimed scope. The claims set forth below- are intended to cover all such variations and modifications, and their equivalents.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The disclosure will be readily understood by the following detailed descripting and in view of the accompanying drawings, where:

[0016] FIG. 1 is atop (plan) view of a traveling-wave parametric amplifier (TWPA);

[0017] FIG. 2 is a cross-sectional view' of an integrated waveguide;

[0018] FIG. 3 is a cross-sectional view of a planar distributed radio frequency (RF) device; and

[0019] FIG. 4 is a plot of a representative gain curve.

[0020] References will be made to details of representative examples and embodiments, and as illustrated in the drawings. These descriptions do not limit the scope of the invention to any "‘preferred” embodiment, or to any of the other examples that are described. Rather, the scope of the invention includes all variations, alternatives, modifications, and equivalents that fall within the scope of the claims.DETAILED DESCRIPTION

[0021] This disclosure relates to electronic devices. More particularly, the disclosure relates to parametric devices. Parametric devices, for example parametric amplifiers, are ty pes of amplifiers or oscillators that operate by varying a circuit parameter periodically (e.g., reactance, or impedance), in order to achieve amplification or oscillation at a different frequency. Parametric devices can also include upconverters, downconverters, circulators, gyrators, isolators, and the like. Parametric devices can be used in low-noise radio receivers, in radio telescopes, spacecraft communication systems, low-noise antennas, quantum computing systems, and other suitable technologies in which amplification of a weak signal is desired.

[0022] Traditional parametric devices can be made from Josephson junction (JJ) devices, or high-kinetic inductance (KI) materials. A Josephson junction consists of two superconducting materials separated by a thin, non-superconducting barrier, through which superconducting electrons can tunnel. High-kinetic inductance materials include materials that exhibit a high-kinetic inductance arising from inertia of charge carriers when current flows in the material. High-kinetic inductance materials can be used in superconducting quantum circuits and other parametric devices. Both Josephson junction (JJ) and high-kinetic inductance (KI) devices depend on superconducting effects; e.g., substantially zero electrical resistance, the Meissner effect, or other superconducting property.

[0023] Operational limitations are imposed on traditional parametric devices due to this dependency, such as limited operational frequency range, limited operational temperature range, and magnetic sensitivity. These limitations can be overcome via parametric devices utilizing nonlinear dielectric media, including strontium titanate (SrTiO3 or STO) based materials.DEFINITIONS

[0024] The term “bulk” can be directed to nonlinear dielectric materials including but not limited to strontium titanate (STO), and includes crystalline or polycrystalline materialsthat are mechanically distinct, uniform, homogenous or unitary. Bulk materials can be disposed on a substrate, carrier, wafer or other base material to form a layer of the bulk material, or on one or more layers of other material.

[0025] The term “thin film" includes powders, films or layers of material that can be deposited, formed or grown on a substrate, carrier, wafer, or other base material. Suitable manufacturing techniques for thin films include, but are not limited to, radio frequency (RF) sputtering, atomic layer deposition (ALD), molecular beam epitaxy (MBE), and other thin film techniques.

[0026] The term “layer’' includes either a layer of bulk material or a thin film layer. A layer of bulk material or thin film can be deposited, formed, or disposed on or above a substrate, or on or above one or more other such layers, or the bulk material can be provided as an independent structure. In this context, what is meant by “bulk” is that the dielectric (e.g., STO) or other material can itself be the substrate; e.g., providing a bulk sample of STO, or cleaving an STO wafer from a boule, and then forming a circuit on top of the bulk wafer material.

[0027] The term “disposed” encompasses a layer of bulk material or a thin film layer that is disposed on or otherwise provided on or adjacent a substrate, carrier, wafer or other base material, or on or adjacent one or more layers of thin film or bulk material.

[0028] The term “parametric device” includes any device configured to modulate an operational circuit parameter (e.g., reactance, impedance, or a combination thereof) via interaction with a nonlinear dielectric medium in order to produce an effect on a signal, for example an oscillation, amplification, frequency up-conversion, frequency downconversion, non-reciprocity, isolation, circulation, transduction, frequency comb generation, or other effect.

[0029] The term “tunable circuit” includes any parametric device configured to utilize the properties of nonlinear dielectric medium to adjust the performance of a given circuit after fabrication, in real time or “on-the-fly,” via an applied control signal (e.g., a bias voltage or current). Examples include, but are not limited to. tunable radio frequency (RF) filters and diplexers, tunable impedance matching networks, voltage-controlled oscillators, and other parametric devices configured for low-noise detection.

[0030] The term “low-noise detection” includes amplitude and / or phase measurements of electromagnetic signals with low added noise, including RF, microwave, andmillimeter-wave (mm-wave) radiation. Applications include, but are not limited to, quantum bit (qubit) readout, communications, radiometry, and remote sensing.

[0031] The term “parametric amplifier’ (PA) includes any parametric device configured to utilize the properties of a nonlinear dielectric medium to mix a pump wave (pump tone or pump waveform) with a signal wave (signal tone or signal waveform), in order to amplify the signal wave to generate an output, and an incidental or idler wave (idler waveform).

[0032] The term “resonant parametric amplifier” (“resonant PA”) includes any parametric amplifier configured for modulation to occurs via an element or effect of a resonant circuit, or via parametric coupling of two or more resonant circuits.

[0033] The term “travelling wave parametric amplifier” (“traveling wave PA” or TWPA) includes any parametric device configured for modulation to occur in anonlinear integrated waveguide, for example a waveguide in which a pump wave, signal wave and idler wave can propagate.

[0034] The term “parametric frequency converter” (PFC) includes any parametric device configured to utilize the properties of a nonlinear dielectric medium to mix a pump wave with a signal wave, in order to transfer the magnitude and / or phase of a signal wave to another frequency, for example an idler wave frequency.

[0035] The term “parametric oscillator” includes any parametric device configured to utilize a nonlinear dielectric medium in conjunction with a pump wave to generate oscillations in a system, or to drive a system into instability.

[0036] The terms “including” and “includes” have the same meanings as “comprising” and “comprises.” The terms “example,” “embodiment,” and “application” refer to specific representative implementations of the invention, and do not limit the scope of the claims except where the corresponding features are expressly recited therein.NONLINEAR DIELECTRIC PARAMETRIC DEVICES

[0037] This disclosure relates to parametric devices utilizing the nonlinear properties of dielectric media, for example strontium titanate (SrTiO3 or STO). STO-based parametric devices provide an alternative to traditional Josephson junction (JJ) and high-kinetic inductance (KI) devices, and to existing electro-optic crystal devices such as Pockels cells. Parametric devices can be configured to utilize the nonlinear properties of selected dielectric media, including STO-based materials, in order to operate over a wide range oftemperatures and frequencies. Suitable operating temperatures can range from millikelvin (mK) to tens of kelvin (K), or up to room temperature. Suitable operating frequencies can range from megahertz (MHz) to sub-gigahertz (sub-GHz) frequencies, or up to hundreds of gigahertz (GHz) or terahertz frequencies (THz), and above.

[0038] Depending on application, suitable operating temperatures can range from less than 1 mK (0.001 K) to 10 mK (0.01 K), or up to 20 mK , 30 mK, 40 mK, 50 mK, 60 mK, 70 mK, 80 mK, 90 mK, or 100 mK (0.1 K), up to 0.2 K, 0.3 K, 0.4 K, 0.5 K, 0.6 K, 0.7 K, 0.8 K, 0.9 K, 1 K, 2 K, 3 K, 4 K, 5 K, 6 K, 7 K, 8 K, 9 K, 10 K, 15 K, 20 K, 25 K, 30 K, 40 K, 50 K or 77 K, or up to room temperature or other ambient temperature range (e.g., 270 K or above, or 290 K or above). The operating temperature can also be less than the room temperature or ambient temperature range (e.g., less than 290 K, or less than 270 K), or less than 77 K, 50 K, 40 K, 30 K, 20 K, 15 K, 14 K, 13 K, 12 K, 11 K, 10 K, 9 K, 8 K, 7 K, 6 K. 5 K, 4 K, 3 K, 2 K, 1 K, 0.9 K, 0.8 K. 0.7 K, 0.6 K, 0.5 K, 0.4 K. 0.3 K, 0.2 K, or 0.1 K (100 mK), or less than 90 mK, 80 mK, 70 mK, 60 mK, 50 mK, 40 mK, 30 mK, 20 mK, or 10 mK, or from 10 mK to 1 mK or below.

[0039] Suitable operating frequencies can range from about 0.001 GHz (1MHz) to 5 MHz, 10 MHz, 50 MHz, 100 MHz (0.1 GHz) or 0.5 GHz (500 MHz), up to 1 GHz, 5 GHz, 10 GHz, 50 GHz, 100 GHz, 200 GHz, 300 GHz, 400 GHz, or 500 GHz, or up to 1 THz (1000 GHz), 10 THz or above. Suitable operating frequencies can also range from less than 10 THz to 1 THz (1000 GHz) or 500 GHz, 400 GHz, 300 GHz, 200 GHz, 100 GHz or below, or less than 50 GHz, 10 GHz, 5 GHz, or 1 GHz, or less than 0.5 GHz (500 MHz), 0.1 GHz (100 MHz), 50 MHz, 10 MHz, 5 MHz, or 1 MHz (0.001 GHz) or below.

[0040] Three different topologies of parametric devices (PDs) can be designed using nonlinear dielectric (e.g., STO-based) materials, depending on the target frequencies and specifications. These include lumped-element based parametric devices, transmission-line based parametric devices, and waveguide-based parametric devices. In some examples, a waveguide can be manufactured by providing a substrate and depositing a base metal layer on a surface of the substrate. The metal can be deposited via RF sputtering, physical vapor deposition (PVD), or other suitable method. The substrate can be made of silicon, sapphire, or silicon-on-sapphire materials, or a combination thereof, or using other suitable substrate materials or combination of materials.

[0041] In some examples, a layer of STO can be deposited on the metal layer, for example with a thickness of about 20 nm, defined transversely or perpendicular to the substrate. Insome examples, 10 nm, 15 nm, 25 nm, or any other suitable thickness of STO can be deposited on the metal layer, or the material can be provided in bulk form. For example, the thickness of the STO layer can be in the range of about 1 nm to about 500 nm. In specific applications, the thickness can be greater than about 0.1 nm, 1 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, or 30 nm, or up to 40 nm, 50 nm, 100 nm, 200 nm, or 500 nm.. Alternatively or in combination, the thickness of the STO layer can be less than about 500 nm, 200 nm, 100 nm, or 50 nm, or up to about 40 nm, 30 nm, 29 nm, 28 nm, 27 nm, 26 nm, 25 nm, 24 nm, 23 nm, 22 nm, 21 nm, 20 nm, 19 nm, 18 nm, 17 nm, 16 nm, 15 nm, 14 nm, 13 nm, 12 nm, 11 nm, 10 nm, 9 nm. 8 nm, 7 nm, 6 nm, 5 nm, 1 nm, or 0.5 nm.

[0042] In some examples, the STO can be deposited via RF sputtering, or any other suitable method. The deposition and substrate can be annealed to enhance the crystallinity in the STO layer. Photolithography can be performed to etch the STO layer, to provide a desired geometry' A top electrode material can be deposited on a top surface of the STO material. In these examples, the top electrode material can be deposited on the STO layer via any suitable coating method.

[0043] In some examples, a parametric amplifier can include a nonlinear transmission line (NLTL) or resonator to interact with a strong pump wave (an electromagnetic drive field) with a small signal to amplify the signal and generate an idler frequency. In these examples, a tunable circuit can include a nonlinear element to alter the small-signal characteristics of a microwave or millimeter-wave device. A bias voltage (e.g., DC) or current can be applied to the nonlinear element to tune the frequency of a pass (stop) band filter, or to fine-tune the impedance matching to an known or unknown load impedance, or for use as a reflective switch.

[0044] In some examples, upconverters can turn microwave photons into optical photons via the nonlinear interaction of a microwave signal with a laser pump wave. STO can have a higher nonlinearity than other candidate photoelectric crystals, like lithium tantalate (LiTaO3 or LT) or lithium niobate (LiNbO3 or LN).

[0045] These and other embodiments are discussed below with reference to FIGS. 1-4. Those skilled in the art will readily appreciate that the detailed description of these figures is for explanatory purposes only and should not be construed as limiting. As used herein, furthermore, any system, method, article, component, feature or sub-feature including atleast one of a first, second option or third disclosed feature should be understood as referring to such a system, method, article, component, feature or sub-feature that can include one or more instances of each identified feature (e.g., one each of the first feature, the second feature, and the third feature, or any combination thereof), or multiple instances of the identified features (e.g., two or more the first, second or third feature), or any combination of the feature, with either the same or different numbers of instances of each feature.PARAMETRIC DEVICES WITH STO-BASED NONLINEAR DIELECTRIC

[0046] FIG. 1 is atop (plan) view of a parametric device 100, for example a traveling-wave parametric amplifier (TWPA), or similar parametric device 100. In these examples, a nonlinear transmission line 110 is disposed on a nonlinear dielectric medium 120, for example a strontium titanate-based (SrTiO3 or STO) material. The nonlinear dielectric 120 can also be provided in bulk form or disposed on a substrate, or deposited over one or more additional layers such as a base conductor 130, with the layered structure provided on a substrate, carrier, wafer, or other base material 140.

[0047] In TWPA applications, parametric device 100 can be configured to amplify a weak input signal by transferring energy from a stronger pump wave; e.g., via interaction with the nonlinear dielectric medium 120. More generally, parametric device 100 can be configured to transfer energy from the pump wave to the signal wave and an idler wave, producing an output with desired frequency, amplitude and phase.

[0048] As illustrated in FIG. 1, for example, nonlinear transmission line 110 extends between an input terminal or port (IN) 150 and an output terminal or port (OUT) 155. Impedance matching can be achieved at the input 150 by tuning or adjusting the equivalent input impedance 160, reactance 161 and capacitance 162 based on an input bias matching or conditioning signal 170 (MATCH BIAS-I), and at the output 155 by tuning the equivalent output impedance 165, reactance 166 and capacitance 167 via an output bias matching or conditioning signal (MATCH BIAS-O) 175.

[0049] As shown in FIG. 1, parametric device 100 can be fabricated with the transmission line 110 disposed a layer of STO-based dielectric 120, or other medium with suitable nonlinear properties. In these examples, device 100 can be configured to function as an integrated, tunable impedance matching network. More generally, parametric device 100 can be configured as a tunable bias network adapted for improved impedance matchingbetween the input 130 (RF IN) and output 135 (RF OUT), using bias matching signals 170, 175 to tune the respect circuit parameters. In some cases, device 100 can be configured to provide substantially perfect impedance matching, reducing reflection and loss mechanisms to substantially zero.

[0050] Suitable nonlinear dielectric media 120 such as strontium titanate (SrTiO3 or STO) can be fabricated in a variety of ways to produce parametric devices 100 with desired properties. Depending upon application, three representative fabrication methodologies and manufacturing techniques can be employed, either alone or in combination.

[0051] For example, transmission line 110 and can be configured as an integrated rectangular waveguide for a device 100 operating in the millimeter-wave (nun-wave) or terahertz (THz) bands; e.g., in a frequency range of about 30 GHz to about 300 GHz, or from about 0.1 THz (100 GHz) up to about 10 THz. In other examples, transmission line 110 can be provided with a planar geometry for use in the microwave region; e.g., from about 300 MHz to about 300 GHz.

[0052] Suitable parametric devices 100 can also be formed with a thin-film component geometry configured to build a tunable or parametric lumped element network with a nonlinear transmission line (NLTL) 110. Optical waveguides can also be etched into the nonlinear dielectric 120 (e.g., either a thin film or bulk dielectric), in order to provide a hybrid optical / microwave / mm-wave parametric device 100. These fabrication methods can be used individually or in any combination to configure parametric device 100 for a range of applications including, but not limited to, parametric amplifiers, frequency upconverters, frequency downconverters, isolators, gyrators, circulators, bidirectional transducers from microwave to optical domains.

[0053] FIG. 2 is a cross-sectional view of an integrated waveguide device 200; e.g., a parametric device 100 with an electrode layer (transmission line) 210 configured as a rectangular waveguide. In these examples, the electrode layer (waveguide) 210 can be disposed on or over a layer 220 of nonlinear dielectric, for example on the top surface 225 of an STO-based dielectric layer 220. The dielectric layer 220 can be disposed on or over a base conductor (e.g., metal) layer 230, which in tun is disposed on or over a substrate, carrier, wafer, or other base material 240.

[0054] In these examples, integrated rectangular waveguide devices 200 can be manufacturedL‘on-chip'' by depositing and patterning any number of conducting layers 210,230 on, over, or adjacent to any number of dielectric layers 220, manufactured on a chipbased substrate material 240 via thin film or bulk deposition techniques. For example, waveguide-type parametric devices 200 can be manufactured by depositing a base conductor (e.g., metal) layer 30 on or onto the substrate 240 via RF sputtering, physical vapor deposition (PVD), thin film deposition, or other suitable method. The substrate 240 can be made of a silicon, sapphire, or silicon-on-sapphire material, or a combination thereof, or using other suitable substrate materials, alone or in combination.

[0055] Nonlinear dielectric layer 230 (e.g., STO) can be disposed or deposited on, over or onto the base conductor layer 220 via RF sputtering, thin film deposition, or other suitable method, or dielectric layer 230 can be provided in bulk form. In some examples, dielectric layer 230 can be provided in a thickness of about 20 nm, or the thickness of dielectric layer 230 may vary'; e.g., from about 10 nm or less up to 15 nm, 25 nm, 30 nm, 40 nm, or 50 nm, or up to 100 nm or more, depending on the desired functionality of parametric device 200 and the corresponding nonlinear properties of the dielectric layer 220.

[0056] The substrate 240, base conductor 230 and dielectric layer 220 can be annealed to enhance crystallinity in the dielectric medium 230, either before or after applying the top conductor (waveguide) layer 210. Patterning, etching, photolithography and other microfabrication processes can also be performed to provide the dielectric layer 220 with a desired geometry; e.g., according to that of the top conductor (waveguide) 210, and the desired operational characteristics of the parametric device 200.

[0057] Depending on application, the top conducting (electrode) layer 210 can be formed of any suitable metal or other conductor, and deposited on or over the dielectric (e.g., STO) layer 220 to form a yvaveguide on the top surface 225 of dielectric layer 220. For example, electrode layer 230 can be formed on the top surface 225 of dielectric layer 230 with a substantially rectangular cross section as shown, or on a selected region of the top surface 225. In these examples, top electrode layer 240 can be deposited via one or more thin film deposition techniques, or using another suitable coating method.

[0058] In operation, parametric device 200 can be configured to propagate a mixed pump wave and signal wave, e.g., in a transverse electric mode (TE01, TE11, or other selected mode), in order to provide parametric amplification of the signal (or “signal tone’') in a desired frequency range. For example, device 200 can be configured for amplification in a narrow-band frequency range of around 75 GHz, or other suitable range. As known in the art, parametric waveguides based on Josephson junction (JJ) devices and other traditionalmethodologies cannot reach 75 GHz, or operate in the frequency range attainable by waveguide device 200.

[0059] FIG. 3 illustrates a planar distributed RF structure for a parametric device 300. In these examples, device 300 can be provided with a planar distributed RF structure by depositing a base conductor (e.g., metal) layer 320 on a substrate 310. The metal layer 320 can be deposited via RF sputtering, physical vapor deposition, thin film deposition, or any other suitable method. The substrate 310 can be made of or comprise a silicon, sapphire, silicon-on-sapphire or other suitable substrate material, or a combination of such materials

[0060] In one example, an approximately 20 nm thickness layer of STO material 330 can be deposited on the first (base) metal or conducting layer 320. Alternatively, a 10 nm.15 nm, 25 nm, or other suitable thickness of STO material 330 can be deposited on the based conducting (e.g., metal) layer 320. The STO material 330 can be deposited via RF sputtering, thin film deposition or other suitable method, or provided in bulk form.

[0061] The deposited STO layer 330, base conductor layer 320 and substrate 310 can be annealed to enhance crystallinity of the strontium titanate (SrTiO3) material. Photolithography can also be performed to etch the STO layer 330.

[0062] In some examples, a second conducting material (top electrode layer) 340 can be deposited on the top surface 335 of the STO layer 330. In these examples, the top electrode material (layer 240) can be deposited via any suitable thin film manufacturing or coating method. For example, a microstrip geometry can be created.

[0063] As illustrated in FIG. 3, the STO layer 330 contact the substrate 310, for example extending along the edge of the base conductor layer 320 to the top surface 315 of the substrate 310. The top electrode layer 340 can also contact the substrate 310. for example extending along the edge of the STO layer 330 to the top surface 315. In this way. the planar distributed RF structure can be used for general distributed or lumped element devices 300. The two-conductor process with a first (base) conductor 310, second (top) conductor 320 and nonlinear dielectric layer 330 this provides a flexible platform for manufacturing a range of different parametric devices 100, 200 and 300, as described herein.

[0064] In some examples, a lumped element, thin-film varactor device 300 can be fabricated. The varactor device 300 can be manufactured by depositing and patterning a bottom electrode 320 on the substrate 310, for example via photolithography, etching orother suitable thin film manufacturing process. In these examples, a photoresist material can also be applied and patterned based on manufacturer-specified processes for the selected geometry of the device 300.

[0065] The thin film, nonlinear dielectric (e.g., STO) layer can be deposited on the top surface via RF sputtering or other suitable process. The remaining photoresist can then be dissolved to lift off unwanted or unneeded portions of the STO layer 330.

[0066] A top electrode layer 340 and / or pattern layer can be deposited on selected portions of the STO layer 330 and substrate 310; e.g., via photolithography. Suitable parametric devices (e.g., varactor devices) 300 formed in this way could be used in tunable coupling circuits to allow for arbitrary under-coupling or over-coupling of the transmission line 110 (see FIG. 1) to a resonator; e.g., that is coupled to one or more different circuits, allowing for switching between readout and other operating modes.

[0067] Optical waveguide devices 300 can also be fabricated on STO layers 330 in a process similar to techniques for forming lithium tantalate (LiTaO3) or lithium niobate (LiNbO3) photonic integrated circuit (PIC). In one such example, a microwave parametric upconverter can be provided (say, operating in a frequency range from 4-10 GHz to 100 GHz), and used as an intermediate step to upconvert more efficiently to the optical domain; e.g., in a triply resonant cavity electro-optic (EO) system using ridge waveguide type devices 300, with STO as the nonlinear dielectric medium.

[0068] More generally, the techniques illustrated in FIGS. 2 and 3 can be used to manufacture a range of different parametric devices 100, 200 and 300, including, but not limited to, upconverters, downconverters, circulators, gyrators, isolators, waveguides and amplifiers, including both traveling wave and resonant parametric amplifiers, as described herein. These devices can be formed with any combination of one or more substrates (or substrate layers) 210, 310, one or more first (base) metal or conducting layers 220, 320, one or more nonlinear dielectric (e.g., STO) media layers 230, 330, and one or more second (top) metal or conductor layers 240, 340, with either planar or non-planar geometry, or any combination, as further described above.

[0069] FIG. 4 is a plot illustrating a gain curve 400. As shown in FIG. 4, a nonlinear dielectric medium such as strontium titanate (SrTiO3 or STO) can be used to interact with a pump wave (pump tone or pump waveform) and signal (signal tone or signal waveform), in order to amplify the signal through generation of an idler tone (idler wave or idlerwaveform). This process can be performed in either a resonant mode (e.g., using a lumped-element fabrication technique), or a traveling-wave mode (e.g.. using the propagation modes of a waveguide or planar-distributed RF structure).

[0070] Amplifiers based on traditional Josephson junction devices and high-kinetic inductance (KI) processes can operate near the quantum limit of noise performance. Strontium titanate (STO) based parametric amplifiers and nonlinear devices can demonstrate similarly low added noise, while operating in a wider range of temperatures and frequencies, with less sensitivity to magnetic fields and other electromagnetic (EM) effects. In these examples, the nonlinear dielectric properties of the STO material can be utilized to solve the nonlinear wave equation in a microwave transmission line to extract the signal gain, for example in a TWPA device with broadband gain curve as shown in FIG. 4.

[0071] More generally, the gain curve of FIG. 4 also represents the frequency response attainable using nonlinear, STO-based dielectric media for a broad range of parametric devices; e.g., in order to mix a signal wave with a local oscillator to upconvert or downconvert the signal frequency to different bands. This process can be performed in lumped element devices, providing substantially improved operating capabilities as compared to traditional diode mixer circuits, or when configured as a distributed element device, functioning as a traveling wave electro-optic modulator.

[0072] Different down-conversion mixer topologies can also be designed, providing double-sideband (DSB), single-sideband (SSB), two-sideband (2SB) down-conversion and I / Q mixing. The up-conversion process can be adapted for both resonant and wide-band modes, and convert from any suitable frequency band to any other suitable band. For example, 1 GHz to 100 GHz upconverters and 1 GHz to 200 THz frequency band converters can be produced using STO-based nonlinear dielectric media, as described herein.

[0073] Parametric isolators can also be produced using STO-based nonlinear dielectric media. In these examples, a traveling-wave frequency converter can be fabricated in one direction, where the down-converted energy comes from a matched resistor. The frequency conversion would take place when the wave is co-propagating with the pump wave, so only one direction would be frequency converted into the dissipated mode. In other examples, the gyration effects of a pumped line can be used; that is. utilizing the differential phase accumulation when propagating alongside the pump wave, versus counter-propagatingwith the pump wave, to create a Mach Zehnder interferometer that constructively interferes in one direction, but destructively interferes in the other.

[0074] As a platform for parametric device design, STO-based nonlinear dielectric media devices can outperform existing alternatives like superconducting DC and RF SQUID devices, Josephson junctions, and device utilizing high-kinetic inductance (KI). In some examples, STO-based devices can operate in a wider range of temperatures, from mK up to tens of K, and over a wider range of frequencies, while maintaining consistent, substantially invariant operational properties.

[0075] STO-based parametric devices, as distinguished from conventional Josephson junction and high-kinetic inductance technologies, do not normally switch out of their nonlinear operating region, and are more resilient to potential manufacturing defects. In addition, STO-based devices are also not subject to “weak link” problems, and they are magnetic-insensitive for fields of up to a few Tesla. As a result, STO-based parametric devise can operate with less shielding, and allow for use in magnetics research and other areas where magnetic fields are present in the operating environment, including spin-qubit readout and topological qubit readout.

[0076] The weak link problem arises, for example, in traditional Josephson junction arrays that are arranged in series to create a traveling wave structure, when pumped near the critical current of the individual junctions, in order to drive a parametric interaction. In these applications, the pump power can be limited by the lowest critical current in the array. If the current through any of thejunctions exceeds the critical current, the junction becomes an open circuit, quickly degrading the parametric interaction of the entire array as a whole. Consequently, even if there are only a few individual junctions in the array with a lower critical current, for example due to manufacturing inconsistencies or defects, the maximum pump power of the array is limited by the lower critical current of those junctions.

[0077] Parametric devices using STO-based nonlinear dielectric media do not suffer from the same weak link problem, because they have no equivalent critical current. If there are defects in the fabrication of some portion of an STO-based structure, this may locally degrade the nonlinearity, but the locally degraded structure will not limit the pump wave in the same way, because there is no open circuit switching behavior at higher pump power. This means that long traveling wave parametric devices can provide better performance when manufactured on STO-based media, and STO-based devices can support longerwaves transmission, allowing for higher overall gain, better isolation, and other improved performance metrics.

[0078] STO-based manufacturing can also simplify the production process, and STO-based media are more compatible with scalable manufacturing processes including CMOS (complementary metal-oxide-semiconductor) techniques, and other semiconductor foundry processes. In some examples, parametric devices with a selectively doped, STO-based nonlinear dielectric medium can also operate at higher temperatures, or even up to room temperature, for example when using barium as dopant, or other suitable doping materials.DISTINCTIONS OVER OTHER PARAMETRIC DEVICES

[0079] There are substantial differences between parametric devices utilizing strontium titanate-based (SrTiO3 or STO) nonlinear dielectric media, as described here, and other, more traditional devices. Traditional cryogenic parametric devices, for example, commonly use superconducting nonlinear components like nanowires, kinetic inductor and Josephson junction (J J) devices or SQUIDs (superconducting quantum interference devices) to achieve the circuit parameter modulation and nonlinearity required for the devices to work.

[0080] These nonlinear superconducting devices all generate a nonlinear inductive element; e.g., where the magnetic flux generated by current flow through the conductor is a nonlinear function of the current. In the case of a SQUID, the relationship is only weakly nonlinear, but it is highly sensitive to external magnetic fields. Thus, an external drive line that generates magnetic flux in the SQUID can be used to modulate the inductance. In the case of a kinetic inductor, nanowire, and Josephson junction, the inductance is pumped with a relatively large pump current, as compared to the relatively weaker signal.

[0081] Microwave frequency parametric amplifiers (including resonant and travelling wave versions) can be constructed from Josephson junctions and SQUIDs. Examples include SQUID-based RF travelling wave parametric amplifiers, high efficiency, low-loss Floquet-mode traveling-wave parametric amplifiers, three-wave mixing kinetic inductance traveling wave amplifiers, and flux-pumped impedance-engineered broadband Josephson parametric amplifiers. Superconducting nonlinear elements have also been used for parametric frequency conversion / isolation, for example in the form of a traveling wave parametric amplifier and converter, or a wideband Josephson parametric isolator.

[0082] Semiconductor diodes and metal / oxide / semiconductor junctions can also be used as nonlinear elements in a parametric device. Suitable nonlinear elements include PN (p-type and n-type semiconductor) junctions, Schottky diodes, PIN (p-type. intrinsic, n-type) junctions, MOS (metal oxide-semiconductor) varactors and MOS nonlinear transmission lines (NLTLs). These components ty pically generate a nonlinear capacitive element; e.g., where the amount of charge accumulated by the terminals of the device is a nonlinear function of the voltage on the device. Generally, the associated nonlinear capacitance curves result from the electric field moving free charges around in order to modulate the width of the depletion region.

[0083] Some semiconductor parametric devices such as cooled varactor parametric amplifiers have relatively fewer practical uses, or have been largely abandoned in favor of lower-noise, transistor-based counterparts. There may still be some relevant applications, however, including nonlinear transmission line devices configured for pulse / comb generation, including gallium arsenide (GaAs) based monolithic microwave integrated circuit (MMIC) non-linear transmission lines, and some semiconductor parametric amplifiers that are operable at cry ogenic temperatures.

[0084] Nonlinear optical and electro-optic devices make up another class of parametric device, further distinguished from superconducting parametric devices. These devices can use other nonlinear dielectric crystals such as lithium tantalate (LiTaO3), lithium niobate (LiNbO3), silicon nitride (SiN), or barium titanate (BTO) to achieve the nonlinearity required for parametric interaction.

[0085] These devices can be provided in chip-based format, operable at room temperature. The nonlinearity7of the dielectric is small, however, and they cannot obviously be used to make a self-modulating microwave circuit, as in the case of the other, semiconductor and superconductor-based parametric devices described above. Instead, they can be employed as parametric devices in the optical domain, where a high-intensity laser pump wave produces amplification or frequency conversion of an optical signal, or undergoes modulation against an applied voltage.

[0086] In these applications, the devices ty pically consist of waveguides etched in a nonlinear dielectric to confine the propagating optical modes: e.g., with a wavelength of around 1550 nm, in an infrared (IR) range commonly used for telecom signals. Multiple optical modes can be mutually coupled by virtue of the dielectric’s nonlinearity', or theycan be modulated by an external voltage or RF mode propagating in the electromagnetic waveguide at a microwave frequency (e.g., 30 GHz).

[0087] Additional electro-optic chip devices have been used for broadband frequency comb generation, for example an ultrabroadband integrated electro-optic frequency comb using lithium tantalate. Other examples include optical parametric amplification, optical frequency conversion and electro-optic modulation, for example octave-spanning tunable infrared parametric oscillators utilized in nanophotonics, visible-to-ultraviolet frequency comb generation using lithium niobate nanophotonic waveguides, intense optical parametric amplification in dispersion-engineered nanophotonic lithium niobate waveguides, integrated low-voltage broadband lithium niobate phase modulators, and integrated lithium niobate electro-optic modulators operating at CMOS-compatible voltages. There are other applications as well, all of which distinguish from the parametric devices described here.ADVANTAGES OF STO-BASED NONLINEAR DIELECTRIC MEDIA

[0088] The use of STO-based nonlinear dielectric media provides substantial advantages over traditional nonlinear optics techniques, in that the devices use a particular nonlinear dielectric crystal, strontium titanate (SrTiO3 or STO), in order to achieve improved parametric coupling. This is different from other nonlinear optics technologies, in that the STO-based medium is configured for fully microwave-range parametric devices. Parametric devices using STO-based materials can also have a much stronger nonlinearity than room-temperature nonlinear crystal materials, and other known nonlinear dielectric media, making STO-based materials suitable for the manufacture of parametric devices operating in the microwave regime.

[0089] In these techniques, the STO-based medium can be provided in thin-film or bulk form, and configured to confine the microwave electric field while maximizing the characteristic impedance, thus improving the parametric coupling. This distinguishes from conventional superconducting devices, by having a voltage-dependent capacitance (arising from the nonlinear dielectric) rather than a current-dependent inductance. A pump wave can then be used to couple other waves together (e.g., by coupling with a signal wave to generate an idler wave), in order to achieve frequency conversion, oscillation, amplifier gain, and other desired outputs.

[0090] These applications of STO-based nonlinear dielectric material to parametric devices are uniquely difference from other superconducting devices, in that the STO-based dielectric is configured to achieve the desired modulation, rather than relying on superconducting effects. In comparison with superconducting Josephson junction (JJ) based devices, for example, STO-based dielectrics may exhibit somewhat weaker nonlinearity, or otherwise require higher pump wave power, but they are also less sensitive to magnetic fields and static shock.

[0091] The process for fabricating a Josephson junction-based device can also be much more complex than for a device using STO-based media, allowing for larger total scale and higher yields. Josephson junction-based nonlinear devices also require long series chains or arrays of potentially thousands of individual junctions, arranged in an interdependent fashion so that if any one of junctions fail the entire device would not function. STO-based parametric device technologies are not subject to this same drawback, because the nonlinearity is embedded in the STO-based dielectric medium itself, rather than in the coupling of multiple, discrete junctions in a multi-layer device.

[0092] In comparison to superconducting devices based on high-kinetic inductance (KI), the parametric, STO-based devices can provide similar levels of nonlinearity and pumppower response, and they are more resistant to magnetic field effects, even understanding that high-kinetic inductance devices can be more resistant than Josephson junction devices. Similarly, high-kinetic inductance devices can also be easier to fabricate than Josephson junction devices, but still more difficult to manufacture than STO-based parametric devices. Based on this, the application of STO-based nonlinear dielectric media to high-kinetic inductance device can yield better performance than exiting technology.

[0093] Another advantage of the use of STO-based nonlinear media in parametric devices is that they can operate at microwave frequencies, extending into the millimeter-wave and THz ranges. This is not possible with other superconducting devices, whether implemented using Josephson junctions or high-kinetic inductance devices.

[0094] Although semiconductor devices can also employ nonlinear capacitance response, the nature of the nonlinearity' in semiconductor variators (and similar semiconductor devices) is fundamentally different from that of STO-based nonlinear dielectric parametric devices. Instead of modulating the depletion region of the semiconductor device to achieve nonlinearity, STO-based media have inherent dielectric nonlinearity. Due to this difference in mechanism, there is a fundamental tradeoff between nonlinearity7and internal loss insemiconductor devices, which is not presented in STO-based parametric devices. This means that semiconductor devices can generate substantially higher added noise, and require higher pump wave power. Semiconductor devices also dissipate too much power to allow for their use at mK temperatures or in larger-scale systems where the integrated heat output can raise operational issues.

[0095] Nonlinear optics devices may share some superficial structural similarities, but STO-based devices utilize barium titanate (BTO), lithium niobate (LiNbO3), lithium tantalate (LiTaO3) and silicon nitride (SiN) media to achieve nonlinearity for parametric interactions, and are thus physically, chemically, structurally and functionally different from the STO-based nonlinear dielectric parametric devices described here.

[0096] This means, more generally, that traditional nonlinear optics devices generate parametric interactions in optical modes, which can be better confined in the corresponding nonlinear media than electronic modes. STO-based devices, in contrast, can achieve microwave-range parametric interactions, rather than being limited to optical interactions. While microwave / microwave parametric devices are an important application of this technology, however, STO-based parametric devices can also be configured for electro / optic (micro wav e / optical or optical / microwave) interactions.EXAMPLES

[0097] Parametric devices can be formed with a base conductor disposed on a substrate, and a layer of nonlinear dielectric disposed on the base conductor; e.g., where the nonlinear dielectric comprises strontium titanate (SrTiO3 or STO). An electrode layer can be disposed on the layer of nonlinear dielectric; e.g., using a conducting material to define a circuit with an input terminal configured for coupling the circuit with a signal, and an output terminal configured for coupling the circuit with an output.

[0098] The nonlinear dielectric can be configured to modulate an operational parameter of the circuit via interaction with a pump wave; e.g., the reactance, or alternatively the impedance. The output is generated based on mixing the signal and the pump wave, also via interaction with the nonlinear dielectric, and as a function of the modulated operating parameter.

[0099] One or both of the signal and the output can include an RF signal having a frequency between 1 MHz and 30 GHz. For example, either the signal or the output can include the RF signal, while the other can include a mm-wave or THz signal with frequency between30 GHz and 300 GHz or between 300 GHz and 30 THz, or an IR or optical signal with frequency between 30 THz and 400 THz, or at least 400 THz.

[0100] The substrate can be formed of silicon, sapphire, silicon-on-sapphire, or a combination thereof. The layer of nonlinear dielectric can be formed from a bulk strontium titanate (STO) material or a thin layer of STO disposed on or over the base conductor or substrate layer, or both, or disposed on each of the base conductor and the substrate.

[0101] The electrode can be configured as a waveguide adapted to sustain an idler wave generated by mixing the pump wave with the signal; e.g., via interaction with the nonlinear dielectric. For example, the waveguide can be configured to sustain the pump wave and the idler wave in one or more resonant modes, where the output is generated by resonant amplification of the signal, or in one or more propagating modes, where the output is generated by traveling wave amplification.

[0102] Modulation of the circuit parameter can be achieved via resonant coupling of the circuit with the pump wave, via the nonlinear dielectric, and the operating parameter can include either reactance or impedance of the circuit. For example, the reactance (or impedance) can vary periodically according to the pump wave, or vary with a different phase proximate the input and output terminals.

[0103] The parametric device can be configured to mix the signal with the pump wave via interaction with the nonlinear dielectric. The interaction also generates an idler wave, and the output is generated by energy transfer between the pump wave and signal via the idler wave. For example, the idler wave can be generated with the same phase or magnitude as the signal (or both), but with a different frequency.

[0104] The output can thus have the same frequency as the signal, or a different frequency; e.g., where the signal is upconverted or downconverted to generate the output. Depending on application, the frequency can be upconverted or downconverted in a radio frequency (RF) range from 1 MHz and 1 GHz, a microwave frequency range from 1 GHz and 30 GHz, or a millimeter wave (mm-wave) frequency range from 30 GHz to 300 GHz, or any combination.

[0105] The parametric device can also include a photonic integrated waveguide; e.g., configured for terahertz (THz) frequencies from 300 GHz to 30 THz, infrared (IR) frequencies from 30 terahertz (THz) to 400 THz, or optical frequencies of at least 400 THz. The frequency of the output can be upconverted or downconverted with respect to thesignal, between any of the terahertz, infrared, or optical frequencies and a radio frequency (RF) from 1 MHz to 1 GHz, a microwave frequency from 1 GHz to 30 GHz, or a millimeter wave (mm-wave) frequency from 30 GHz to 300 GHz, or any combination.

[0106] A filter can be coupled to the circuit proximate the output terminal; e.g., where the filter is configured for isolating the signal or output, or for non-reciprocal flow of the signal or output between the input and output terminals. A bias matching input can be connected to the circuit, and configured to modulate the reactance or inductance, for example based on a direct current (DC) bias matching signal. Both input and output bias matching inputs can be provided, in order to modulate the reactance (or inductance) with different values.

[0107] Methods for operating a parametric device are also provided, according to any of the examples above. These methods can include receiving the signal via the input terminal; e.g., where the pump wave and signal are mixed via interaction with the nonlinear dielectric, generating the idler wave, and producing the output via the output terminal; e.g., by energy’ transfer between the pump wave and signal, via the idler wave.

[0108] The signal can be amplified, for example where the output has the same frequency as the signal, but a different amplitude. The signal can also be upconverted or downconverted the signal, so that the output has a different frequency.

[0109] Methods for manufacturing the parametric device can include providing the substrate, disposing the base conductor on the substrate, and disposing the layer of nonlinear dielectric on the base conductor; e.g., wherein the nonlinear dielectric comprises strontium titanate in either bulk or thin film form. The electrode layer can be disposed on the layer of nonlinear dielectric, using a conducting metal to define the circuit. The substrate, base conductor and nonlinear dielectric can be annealed, and the electrode layer can be etched or otherwise microfabricated to define a waveguide configured to sustain the signal, the pump wave and the idler wave, in one or more resonant or propagating modes.

[0110] According to any of these examples, both thin film and bulk strontium titanate (STO) materials can be used in developing and manufacturing a range of different parametric devices including, but not limited to. parametric amplifiers, upconverters. downconverters, circulators, gyrators, isolators, RF and microwave to THz and optical converters, and tunable microwave circuits. The use of STO-based materials in these devices provides a versatile alternative to existing Josephson junction (JJ) and Kinetic Inductance (KI) based devices, and electro-optic crystal devices such as Pockels cells.These devices are also capable of operating over a wider range of temperatures (e.g., from mK to tens of K, or even up to room temperature), and frequencies (e.g., sub-GHz to hundreds of GHz), with little or virtually (or substantially) no power limitations.

[0111] These and other parametric devices can be formed from a substrate, a metal layer disposed on the substrate, and a layer of strontium titanate (SrTiO3) disposed on the metal layer. The substrate can be comprised of silicon, sapphire, silicon-on-sapphire, or a combination. The strontium titanate layer can be deposited via RF sputtering, or other suitable technique. The strontium titanate layer can have a thickness of about 20 nm, or more than 20 nm, or less than 20 nm. An electrode can be disposed on the layer of strontium titanate, and configure to provide the device with desired functionality’.

[0112] In waveguide applications, for example, the first (base) metal layer can be disposed on a substrate, with a layer of strontium titanate on the metal layer, and a top electrode on the layer of strontium titanate. Suitable methods of manufacture can include annealing the waveguide in a vacuum furnace, either before or after depositing the top electrode layer. Photolithography can be used to etch the strontium titanate layer, and sidewalls can be deposited on either the etched strontium titanate, or any of the other layers. The strontium titanate layer can be about 20 nm thick, or thicker or thinner than 20 nm.

[0113] Varactors can also be formed by depositing a bottom electrode (e.g., on a substrate), patterning the bottom electrode, applying a photoresist to the patterned bottom electrode, depositing a strontium titanate layer over the photoresist, and depositing a top electrode on the strontium titanate layer. The photoresist can be dissolved to lift off a portion of the strontium titanate, for example an unneeded or unwanted portion in regions without the top electrode.

[0114] This description is provided for the purposes of illustration and explanation, using specific nomenclature to provide a thorough understanding of the examples that are described. It will be apparent to anyone skilled in the art that not all the specific details that are disclosed are required to practice the invention as claimed. The description is not exhaustive, and does not limit the claims to any' of the examples that are disclosed, except as expressly cited in the claim language.

[0115] It will also be apparent to one of ordinary' skill in the art, having read this application, that modifications and variations of these techniques are possible in view of the above teachings, while remaining consistent with the scope of the invention as claimed. While various applications have been described with reference to certain specific features.moreover, as adapted to particular problems and examples, other variations are also possible, without departing from the claimed scope. The claims set forth below are intended to cover all such variations and modifications, and their equivalents.

Claims

CLAIMS1. A parametric device comprising:a nonlinear dielectric provided in bulk form or disposed on a substrate, wherein the nonlinear dielectric comprises strontium titanate (SrTiO3 or STO);an electrode disposed on the nonlinear dielectric, wherein the electrode comprises a conducting material defining a circuit;an input port configured for coupling the circuit with a signal; andan output port configured for coupling the circuit with an output;wherein the nonlinear dielectric is configured to modulate an operational parameter of the circuit via interaction with a pump wave, wherein the output is generated based on mixing the signal and the pump wave as a function of the modulated operating parameter.

2. The parametric device of claim 1, wherein one or both of the signal and the output comprises a radio frequency (RF) signal having a frequency between 1 MHz and 30 GHz.

3. The parametric device of claim 2, wherein one of the signal and the output comprises the RF signal and the other comprises a millimeter-wave (mm- wave) or terahertz (THz) signal having a frequency between 30 GHz and 300 GHz, or between 300 GHz and 30 THz.

4. The parametric device of claim 2, wherein one of the signal and the output comprises the RF signal and the other comprises an infrared (IR) signal having a frequency between 30 terahertz (THz) and 400 THz, or an optical signal having a frequency of at least 400 THz.

5. A parametric device according to any of the above claims, wherein the nonlinear dielectric is disposed on the substrate.

6. The parametric device of claim 5, wherein the substrate comprises silicon, sapphire, silicon-on-sapphire, silicon plus silicon dioxide (SiO2) or thermal oxide, silicon carbide (SiC), magnesium oxide (MgO), or a combination thereof.

7. A parametric device according to claim 5 or claim 6, further comprising a base conductor disposed on the substrate, wherein the nonlinear dielectric is disposed on the base conductor.

8. A parametric device according to any of the above claims, wherein:the nonlinear dielectric comprises a bulk strontium titanate material or a layer of strontium titanate material disposed on or over a base conductor or the substrate, or both, or a layer of strontium titanate material disposed on each of a base conductor and the substrate; orthe nonlinear dielectric comprises a thin film of strontium titanate deposited on or over the base conductor or the substrate, or both, or deposited on each of the base conductor and the substrate..

9. A parametric device according to any of the above claims, wherein the electrode defines a waveguide configured to sustain an idler wave generated by mixing the pump wave with the signal via interaction with the nonlinear dielectric.

10. The parametric device of claim 9, wherein the waveguide is configured to sustain the pump wave and the idler wave in one or more resonant modes, wherein the output is generated by resonant amplification of the signal.

11. The parametric device of claim 9, wherein the waveguide is configured to sustain the pump wave and the idler wave in one or more propagating modes, wherein the output is generated by traveling wave amplification of the signal.

12. A parametric device according to any of the above claims, wherein the modulation comprises resonant coupling of the circuit with the pump wave via the nonlinear dielectric, wherein the operating parameter comprises reactance of the circuit.

13. The parametric device of claim 12, wherein the reactance of the circuit varies periodically according to the pump wave, wherein the reactance of the circuit varies with a different phase proximate the input port and the output port, or both.

14. A parametric device according to any of the above claims, wherein the device is configured to mix the signal with the pump wave via interaction with the nonlinear dielectric, wherein an idler wave is generated, and wherein the output is generated by energy transfer between the pump wave and signal, via the idler wave.

15. The parametric device of claim 14, wherein the idler wave is generated with a same phase of the signal or a same magnitude of the signal, or both, and with a different frequency from the signal.

16. The parametric device of claim 14, wherein the output has a different frequency from the signal, wherein the frequency of the signal is upconverted or downconverted to generate the output.

17. The parametric device of claim 16, wherein the frequency of the input is upconverted or downconverted between a radio frequency (RF) range from 1 MHz and 1 GHz. a microwave frequency range from 1 GHz and 30 GHz. or a millimeter wave (mm-wave) frequency range from 30 GHz to 300 GHz, or any combination thereof.

18. A parametric device according to any of the above claims, further comprising a photonic integrated waveguide configured for terahertz (THz) frequencies from 300 GHz to 30 THz, infrared (IR) frequencies from 30 terahertz (THz) to 400 THz, or optical frequencies of at least 400 THz.

19. The parametric device of claim 18. wherein the frequency of the signal is upconverted or downconverted between any of the terahertz, infrared, or optical frequencies and a radio frequency (RF) from 1 MHz to 1 GHz, a microwave frequency from 1 GHz to 30 GHz, or a millimeter wave (mm-wave) frequency from 30 GHz to 300 GHz, or any combination thereof.

20. A parametric device according to any of the above claims, further comprising a filter coupled to the circuit, wherein the filter is configured for isolating the signal or output, or for non-reciprocal flow of the signal or output between the input port and the output port.

21. A parametric device according to any of the above claims, further comprising a bias matching input connected to the circuit, wherein the bias matching input is configured to modulate a reactance or inductance of the circuit.

22. The parametric device of claim 21, wherein:the bias matching input is configured to modulate the reactance of the circuit proximate the input port, based on a direct current (DC) input bias matching signal; andfurther comprising a second bias matching input configured to modulate the reactance of the circuit proximate the output termina, based on a DC output bias matching signal.

23. A method for operating a parametric device according to any of the above claims, the method comprisingreceiving the signal via the input port, wherein the pump wave and signal are mixed via interaction with the nonlinear dielectric, generating an idler wave; and generating the output via the output port, wherein the output is generated by energy transfer between the pump wave and signal, via the idler wave.

24. The method of claim 23, further comprising amplifying the signal, wherein the output has a same frequency as the signal, and a different amplitude.

25. The method of claim 23, further comprising upconverting or downconverting the signal, wherein the output has a different frequency with respect to that of the signal.

26. A method for manufacturing a parametric device according to any of claims 1-22, the method comprising:providing the nonlinear dielectric, wherein the nonlinear dielectric comprises the strontium titanate (SrTiO3 or STO) in bulk or thin film form; and disposing the electrode on the nonlinear dielectric, wherein the electrode comprises a conducting metal defining the circuit.

27. The method of claim 26, wherein the nonlinear dielectric is disposed on a substrate.

28. The method of claim 27. further comprising disposing a base conductor on the substrate, wherein the nonlinear dielectric is disposed on the base conductor.

29. A method according to any of claims 26, 27 or 28, further comprising:annealing one or more of the substrate and the nonlinear dielectric.

30. A method according to any of claims 26-29, further comprising:etching the electrode;wherein the conducting metal defines a waveguide configured to sustain the signal;andwherein the pump wave and an idler wave generated by mixing the signal and pump wave via interaction with the nonlinear dielectric, in one or more resonant or propagating modes.

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