WO2019190550A1

WO2019190550A1 - Guided wave tera-hertz generation apparatus and method using spin orbit effect

Info

Publication number: WO2019190550A1
Application number: PCT/US2018/025399
Authority: WO
Inventors: Sasikanth Manipatruni; Dmitri E. Nikonov; Ian A. Young
Original assignee: Intel Corporation
Priority date: 2018-03-30
Filing date: 2018-03-30
Publication date: 2019-10-03

Abstract

An apparatus is provided which comprises: a first waveguide (e.g., ferrimagnetic material) to convert an optical pulse into spin current; a structure (e.g., spin orbit material) adjacent to the first waveguide, wherein the structure is to convert the spin current into charge current; and a second waveguide (e.g., metal) adjacent to the structure, wherein the second waveguide is to carry an electromagnetic wave produced from the charge current.

Description

GUIDED WAVE TERA-HERTZ GENERATION APPARATUS AND METHOD USING

SPIN ORBIT EFFECT

BACKGROUND

[0001] Tera-Hertz (THz) radiation is a radio-frequency (RF) radiation spectrum that can provide access to new technologies. These new technologies include new imaging techniques for medical and industrial applications, new communication bandwidth for ultra high speed fast interconnects, and new method for understanding foundational physicals of the THz phenomenon. Improving the efficiency of THz generation is a constant challenge.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] The embodiments of the disclosure will be understood more fully from the detailed description given below and from the accompanying drawings of various embodiments of the disclosure, which, however, should not be taken to limit the disclosure to the specific embodiments, but are for explanation and understanding only.

[0003] Fig. 1A illustrates a high level operating principle for THz generation, in accordance with some embodiments.

[0004] Fig. IB illustrates a plot showing spectrum of waveguide integrated spintronic

THz source, in accordance with some embodiments.

[0005] Fig. 2A illustrates a three dimensional (3D) view apparatus for THz signal generation, in accordance with some embodiments.

[0006] Fig. 2B illustrates a top view of the apparatus of Fig. 2A, in accordance with some embodiments.

[0007] Figs. 3A-C illustrate cross-sections of a super lattice based spin orbit material, respectively, according to some embodiments of the disclosure.

[0008] Fig. 4 illustrates a general perovskite structure.

[0009] Figs. 5A-C illustrate a three dimensional (3D) view of a charged perovskite, and a 3D view of a neutral perovskite, respectively, according to some embodiments of the disclosure.

[0010] Figs. 6A-G illustrate a hollow-core single clad waveguide, hollow-core hybrid-clad waveguide, and metal waveguide with thin layer of metamaterial as inner cladding, a coaxial transmission line, a stripline, a microstrip transmission line, and a coplanar waveguide, respectively, in accordance with some embodiments. [0011] Fig. 7 illustrates a flowchart for forming the apparatus of Figs. 2A-B, in accordance with some embodiments.

[0012] Fig. 8 illustrates a SoC (System-on-Chip) with coupled to THz generation source, according to some embodiments of the disclosure.

DETAILED DESCRIPTION

[0013] Various embodiments describe a spintronic THz generation apparatus which provides spin based THz generation where a THz source is largely dictated by time scales of electron diffusion and relaxation and as such, there is little to no spectral imprint on materials. The THz spintronic source of some embodiments provides access to new spectral regions that were previously not accessible via traditional THz sources. The THz spintronic source enables the use of a wide class of spin orbit coupling materials.

[0014] In some embodiments, the THz generation apparatus comprises a first waveguide to convert an optical pulse into spin polarized current. In some embodiments, the first waveguide is able to guide an optical pump pulse operating at optical wavelengths, typically with the wavelength in vacuum between 100 nm (nanometers) and 10000 nm (e.g., frequency between 30 THz to 3000 THz). In some embodiments, the THz generation apparatus comprises a second waveguide adjacent to the first waveguide, wherein the second waveguide is to convert the spin polarized current into charge current. For example, a spin orbit material of the second waveguide is integrated into a guided wave structure to efficiently convert input spin polarized current into charge current. The charge current has a vector direction orthogonal to the direction of spin polarized current, and this charge current generates an electric field and a corresponding magnetic field. These electric and magnetic fields switch directions causing generation of electromagnetic waves (THz waves). In some embodiments, the THz generation apparatus comprises a second waveguide adjacent to the second waveguide, wherein the second waveguide is to carry the electromagnetic waves produced from the charge current. In some embodiments, the electromagnetic waves are received by a processor where they are processed (e.g., for image processing).

[0015] In some embodiments, the THz waveguide is a ground-signal-ground (GSG) configuration where the THz waveguide that propagates the THz signal is in the center while the ground lines are on either sides or surrounding the THz waveguide. In some

embodiments, the waveguide structure is able to guide both an optical pump operating at optical wavelengths, and THz wave operating at 1-30 THz center frequency. [0016] In some embodiments, the first waveguide which is an optical receiving medium, comprises a ferrimagnetic material (e.g., a low loss magnetic garnets such as Gadolinium Gallium Garnet (GGG) or Yttrium Iron Garnet (YIG), or spinel based transparent magnetic insulators). Here, the term‘ferrimagnetic material” generally refers to a material with a set of sublattices, each having magnetic order of spins. In this sense, ferromagnetic materials will be included in this class. In some embodiments, the

ferrimagnetic material comprises one of the elements: Y, Fe, Al, Co, Ni, Mg, Zn, Ba, Rb, S, Gadolinium, Gallium, or O. In some embodiments, the spin orbit material comprises a super lattice of a neutral perovskite and a charged perovskite, wherein the neutral perovskite comprises a group 2 element and oxygen, and wherein the charged perovskite comprises one of a group 3d, 4d, or 5d transition metal and oxygen, or wherein the neutral perovskite comprises one or both of: Sr and O; or Ti and O, and wherein the charged perovskite comprises one or both of: Al and O; or La and O. For example, spin orbit materials that convert spin to charge comprise Pt, Ta, W, Ir, CuBi, Bi, or high spin orbit oxides such as SrlrCri or BhCh. In some embodiments, the spin orbit material comprises one or more of: b- Tantalum (b-Ta), Ta, b-Tungsten (b-W), W, Platinum (Pt), Copper (Cu) doped with elements including on of Iridium, Bismuth or elements of 3d, 4d, 5d and 4f, 5f periodic groups, Ti, S, W, Mo, Se, B, Sb, Re, La, C, P, La, As, Sc, O, Bi, Ga, Al, Y, In, Ce, Pr, Nd, F, Ir, Mn, Pd, or

Fe. In some embodiments, the super lattice also comprises a spin filtering layer such as Ni2Fe04 or spin symmetry filter such as MgO, MgAlCri.

[0017] In the following description, numerous details are discussed to provide a more thorough explanation of embodiments of the present disclosure. It will be apparent, however, to one skilled in the art, that embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring embodiments of the present disclosure.

[0018] Note that in the corresponding drawings of the embodiments, signals are represented with lines. Some lines may be thicker, to indicate more constituent signal paths, and/or have arrows at one or more ends, to indicate primary information flow direction. Such indications are not intended to be limiting. Rather, the lines are used in connection with one or more exemplary embodiments to facilitate easier understanding of a circuit or a logical unit. Any represented signal, as dictated by design needs or preferences, may actually comprise one or more signals that may travel in either direction and may be implemented with any suitable type of signal scheme. [0019] The term“free” or“unfixed” here with reference to a magnet refers to a magnet whose magnetization direction can change along its easy axis upon application of an external field or force (e.g., Oersted field, spin torque, etc.). Conversely, the term“fixed” or “pinned” here with reference to a magnet refers to a magnet whose magnetization direction is pinned or fixed along an axis and which may not change due to application of an external field (e.g., electrical field, Oersted field, spin torque,).

[0020] Here, perpendicularly magnetized magnet (or perpendicular magnet, or magnet with perpendicular magnetic anisotropy (PMA)) refers to a magnet having a magnetization which is substantially perpendicular to a plane of the magnet or a device. For example, a magnet with a magnetization which is in a z-direction in a range of 90 (or 270) degrees +/- 20 degrees relative to an x-y plane of a device.

[0021] Here, an in-plane magnet refers to a magnet that has magnetization in a direction substantially along the plane of the magnet. For example, a magnet with a magnetization which is in an x or y direction and is in a range of 0 (or 180 degrees) +/- 20 degrees relative to an x-y plane of a device.

[0022] The term“device” may generally refer to an apparatus according to the context of the usage of that term. For example, a device may refer to a stack of layers or structures, a single structure or layer, a connection of various structures having active and/or passive elements, etc. Generally, a device is a three-dimensional structure with a plane along the x-y direction and a height along the z direction of an x-y-z Cartesian coordinate system. The plane of the device may also be the plane of an apparatus which comprises the device.

[0023] Throughout the specification, and in the claims, the term "connected" means a direct connection, such as electrical, mechanical, or magnetic connection between the things that are connected, without any intermediary devices.

[0024] The term "coupled" means a direct or indirect connection, such as a direct electrical, mechanical, or magnetic connection between the things that are connected or an indirect connection, through one or more passive or active intermediary devices.

[0025] The term“adjacent” here generally refers to a position of a thing being next to

(e.g., immediately next to or close to with one or more things between them) or adjoining another thing (e.g., abutting it).

[0026] The term "circuit" or“module” may refer to one or more passive and/or active components that are arranged to cooperate with one another to provide a desired function. [0027] The term "signal" may refer to at least one current signal, voltage signal, magnetic signal, or data/clock signal. The meaning of "a," "an," and "the" include plural references. The meaning of "in" includes "in" and "on."

[0028] The term“scaling” generally refers to converting a design (schematic and layout) from one process technology to another process technology and subsequently being reduced in layout area. The term“scaling” generally also refers to downsizing layout and devices within the same technology node. The term“scaling” may also refer to adjusting (e.g., slowing down or speeding up - i.e. scaling down, or scaling up respectively) of a signal frequency relative to another parameter, for example, power supply level.

[0029] The terms“substantially,”“close,”“approximately,”“near,” and“about,” generally refer to being within +/- 10% of a target value. For example, unless otherwise specified in the explicit context of their use, the terms“substantially equal,”“about equal” and“approximately equal” mean that there is no more than incidental variation between among things so described. In the art, such variation is typically no more than +/-l0% of a predetermined target value.

[0030] Unless otherwise specified the use of the ordinal adjectives“first,”“second,” and“third,” etc., to describe a common object, merely indicate that different instances of like objects are being referred to and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking or in any other manner.

[0031] For the purposes of the present disclosure, phrases“A and/or B” and“A or B” mean (A), (B), or (A and B). For the purposes of the present disclosure, the phrase“A, B, and/or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0032] The terms“left,”“right,”“front,”“back,”“top,”“bottom,”“over,”“under,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. For example, the terms“over,” “under,”“front side,”“back side,”“top,”“bottom,”“over,”“under,” and“on” as used herein refer to a relative position of one component, structure, or material with respect to other referenced components, structures or materials within a device, where such physical relationships are noteworthy. These terms are employed herein for descriptive purposes only and predominantly within the context of a device z-axis and therefore may be relative to an orientation of a device. Hence, a first material“over” a second material in the context of a figure provided herein may also be“under” the second material if the device is oriented upside-down relative to the context of the figure provided. In the context of materials, one material disposed over or under another may be directly in contact or may have one or more intervening materials. Moreover, one material disposed between two materials may be directly in contact with the two layers or may have one or more intervening layers. In contrast, a first material“on” a second material is in direct contact with that second material. Similar distinctions are to be made in the context of component assemblies.

[0033] The term“between” may be employed in the context of the z-axis, x-axis or y- axis of a device. A material that is between two other materials may be in contact with one or both of those materials, or it may be separated from both of the other two materials by one or more intervening materials. A material“between” two other materials may therefore be in contact with either of the other two materials, or it may be coupled to the other two materials through an intervening material. A device that is between two other devices may be directly connected to one or both of those devices, or it may be separated from both of the other two devices by one or more intervening devices.

[0034] Here, multiple non-silicon semiconductor material layers may be stacked within a single fin structure. The multiple non-silicon semiconductor material layers may include one or more“P-type” layers that are suitable (e.g., offer higher hole mobility than silicon) for P-type transistors. The multiple non-silicon semiconductor material layers may further include one or more one or more“N-type” layers that are suitable (e.g., offer higher electron mobility than silicon) for N-type transistors. The multiple non-silicon

semiconductor material layers may further include one or more intervening layers separating the N-type from the P-type layers. The intervening layers may be at least partially sacrificial, for example to allow one or more of a gate, source, or drain to wrap completely around a channel region of one or more of the N-type and P-type transistors. The multiple non-silicon semiconductor material layers may be fabricated, at least in part, with self-aligned techniques such that a stacked CMOS device may include both a high-mobility N-type and P-type transistor with a footprint of a single FinFET.

[0035] For the purposes of present disclosure, the terms“spin” and“magnetic moment” are used equivalently. More rigorously, the direction of the spin is opposite to that of the magnetic moment if the charge of the particle is negative (such as in the case of electron).

[0036] It is pointed out that those elements of the figures having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described but are not limited to such.

[0037] Fig. 1A illustrates a high level operating principle 100 for THz generation, in accordance with some embodiments. The operating principle 100 shows an ultra-short input optical pulse 101 which is provided as input to a first waveguide 104. The optical pulse is absorbed by the ferrimagnetic material of the waveguide with creation of free carriers in bands with a definite value of spin polarization determined by the magnetization of the ferrimagnet. This magnetization is fixed and does not change in the operation of the device. Thus the first waveguide 104 converts the optical pulse into a corresponding spin polarized current. In some embodiments, the input optical pulse 101 is generated by a femtosecond pump. In some embodiments, the first waveguide 104 comprises an insulating low loss magnetic material such as YIG or GGG. The optical pulse 101 (e.g., a femtosecond laser pulse) excites electrons in the material of waveguide 104, whereby changing their band velocity and launching a charge current 102 along the z-direction. In this case, since the mobility of spin-up (majority) electrons l02a is significantly higher than that of spin-down (minority) electron l02b, the z-current 102 is spin polarized.

[0038] In some embodiments, the spin polarized current 102 is received by structure

105 which converts the spin polarized current 102 into corresponding charge current. In some embodiments, structure 105 comprises the spin orbit material which includes a super lattice of a neutral perovskite and a charged perovskite, wherein the neutral perovskite comprises a group 2 element and oxygen, and wherein the charged perovskite comprises one of a group 3d, 4d, or 5d transition metal and oxygen, or wherein the neutral perovskite comprises one or both of: Sr and O; or Ti and O (e.g., STO), and wherein the charged perovskite comprises one or both of: Al and O; or La and O (LaO). For example, spin orbit materials that convert spin to charge comprise Pt, Ta, W, Ir, CuBi, Bi, or high spin orbit oxides such as SrlrCri or BriCh. In some embodiments, the spin orbit material comprises one or more of: b-Tantalum (b-Ta), Ta, b-Tungsten (b-W), W, Platinum (Pt), Copper (Cu) doped with elements including on of Iridium, Bismuth or elements of 3d, 4d, 5d and 4f, 5f periodic groups, Ti, S, W, Mo, Se, B, Sb, Re, La, C, P, La, As, Sc, O, Bi, Ga, Al, Y, In, Ce, Pr, Nd, F, Ir, Mn, Pd, or Fe. In some embodiments, the super lattice also comprises a spin filtering layer such as NriFeCri or spin symmetry filter such as MgO, MgAlCri.

[0039] The spin-orbit interaction deflects spin-up and spin-down electrons in opposite directions and transforms the spin current ./ 107 into an ultrafast transverse charge current J_c 108 leading to the emission of a THz electromagnetic pulse 103. The

electromagnetic pulse 103 comprises an electrical field E and a corresponding magnetic field M, which vary with coordinate, and which are generated by the charge current ./ 108. In some embodiments, structure 105 is coupled to a second waveguide 106. In various embodiments, the second waveguide 106 is a waveguide that is configured to carry the THz electromagnetic pulse 103.

[0040] Fig. IB illustrates plot 120 showing calculated spectrum of transmission of integrated THz waveguide, in accordance with some embodiments. Here, the x-axis is frequency in THz while the y-axis is Amplitude (normalized) and Phase. The waveform 121 is the amplitude of the transmitted THz signal 103, while the waveform 122 is the electric field of the output THz signal from second waveguide 106.

[0041] Fig. 2A illustrates a three dimensional (3D) view of apparatus 200 for THz signal generation, in accordance with some embodiments. Fig. 2B illustrates a top view 220 of apparatus 200, in accordance with some embodiments. In some embodiments, apparatus 200 comprises a first waveguide 209 having a first structure 201 and a second structure 202. While various embodiments describe the first waveguide 201 has having two structures, the first waveguide 209 may just comprise structure 201 while structure 202 is adjacent to structure 201 of the first waveguide 209.

[0042] In some embodiments, first waveguide 209 comprises an input section 211

(e.g., to receive optical pulse 101), an output section 213 (e.g., on the opposite end of the input section), and a body between the input and output sections, wherein the body is longer than the input or output sections (e.g., Lopticai plus Lsoc is longer than Wopticai). In some embodiments, the first structure 201 comprises a ferrimagnetic material, wherein the first structure has an input section 211 (e.g., to receive an optical pulse 101), an output section 212 (e.g., to provide spin polarized current Js), and a body, wherein the input section 211 of the first structure is same as the input section of the first waveguide 209.

[0043] In some embodiments, the second structure 202/106 is adjacent to the first structure 201, wherein the second structure 202 comprises a spin orbit coupling (SOC) material. In some embodiments, the second structure 202 has an input section 212, an output section 213, and a body between the input 212 and output 213 sections, wherein the input 212 of the second structure 202 is adjacent to the output of the first structure 201, wherein the output of the second structure 202 is same as the output of the first waveguide 201. In various embodiments, the bodies of the first and second structures together equal the body of the first waveguide 209. For example, L_opticai plus Lsoc is the equal to the length of the body of the first waveguide 209. The lateral size Wopticai of the core 211 of the optical waveguide 209 is comparable to the wavelength of the optical pulse. In some embodiments, apparatus 200 comprises a second waveguide 210 adjacent to the first waveguide 209, wherein the second waveguide 210 has an input section 214. In some embodiments, the input section 214 is substantially smaller than the input of the first waveguide 209. In some embodiments waveguide 210 is implemented as a twin wire transmission line comprising metal wires 206 and 207. In other embodiments waveguide 210 is implemented as a stripline transmission line, a microstrip transmission line, a coaxial transmission line, or a coplanar waveguide, each having a plurality of metal wires. The lateral size WTH_Z of the waveguide 210 is comparable to the wavelength of the terahertz pulse and thus is significantly larger than W optical.

[0044] In some embodiments, the ferrimagnetic material of the first structure 201 includes one or more of elements: Y, Fe, Al, Co, Ni, Mg, Zn, Ba, Rb, S, or O. In some embodiments, the ferrimagnetic material is a low loss magnetic garnets such as Gadolinium Gallium Garnet (GGG) or Yttrium Iron Garnet (YIG), or spinel based transparent magnetic insulators. Other possible ferrimagnetics are barium ferrite (such as BaFe Ow), manganese zinc ferrite (such as Mn_aZn(i-_a)Fe204, where‘a’ is a number), nickel-zinc ferrite (such as Ni_aZn(i_-a)Fe204, where‘a’ is a number), strontium ferrite (such as SrFe Ow, Sr0.6Fe203), cobalt ferrite (such as CoFe204, CoOFe203).

[0045] In some embodiments, the magnetization of the ferrimagnetic material of the first structure 201 determines the spin polarization of the spin polarized current J_s. The direction of flow of the spin polarized current./ is set by the direction of propagation of the optical pulse. In some embodiments, when the first structure 201 is always used as an input stage to receive an optical pulse. Some factors that may determine the direction of magnetization of the ferrimagnetic material can be thickness of the ferrimagnetic material in the x-direction, surface anisotropy (depending on the adjacent layers or a multi-layer composition of the ferrimagnetic material) and/or crystalline anisotropy (depending on stress and the crystal lattice structure modification such as FCC (face centered cubic lattice), BCC (body centered cubic lattice), or Llo-type of crystals, where Llo is a type of crystal class which exhibits perpendicular magnetizations), can also determine the direction of magnetization. In some embodiments, the length L_0ptic3i of the first structure 201/104 is in a range of 1 pm to 300 pm. In some embodiments, the length W₀ptic_ai of the first structure 201/104 is in a range of 1 pm to 20 pm.

[0046] In some embodiments, the spin orbit material of the second structure 202/106 comprises a super lattice of a neutral perovskite and a charged perovskite. In some embodiments, the neutral perovskite comprises a group 2 element and oxygen, and wherein the charged perovskite comprises one of a group 3d, 4d, or 5d transition metal and oxygen, or wherein the neutral perovskite comprises one or both of: Sr and O (SRO); or Ti and O. In some embodiments, the charged perovskite comprises one or both of: Al and O; or La and O (LAO). In some embodiments, the super lattice of the spin orbit material of the second structure 202/106 comprises a super lattice of Bi, Ag, and Cu repeated 2 or more times (e.g., 100 times). In some embodiments, the super lattice of the spin orbit material of the second structure 202/106 comprises a super lattice of LAO (e.g., LaAlOs), STO (e.g., SrTi03), and BTO (e.g., BaTi03) together repeated 2 or more times (e.g., 100 times). In some

embodiments, the super lattice of the spin orbit material of the second structure 202/106 comprises a super lattice of LAO, STO, and SRO together repeated 2 or more times (e.g., 100 times). In some embodiments, the super lattice of the spin orbit material of the second structure 202/106 comprises a super lattice of Pt, Garnet, and W together repeated 2 or more times (e.g., 100 times).

[0047] In some embodiments, the spin orbit material exhibits spin Hall effect (SHE).

In some embodiments, these materials may exhibit Rashba-Edelstein effect (e.g., when the magnetization of the ferrimagnetic material is in-plane along the z or y-direction, parallel to the plane z-y of the device). In some embodiments, the spin orbit material that exhibit exhibits Rashba-Edelstein effect comprises one or more or: b-Tantalum (b-Ta), Ta, b- Tungsten (b-W), W, Platinum (Pt), Copper (Cu) doped with elements including on of Iridium, Bismuth or elements of 3d, 4d, 5d and 4f, 5f periodic groups, Ti, S, W, Mo, Se, B, Sb, Re, La, C, P, La, As, Sc, O, Bi, Ga, Al, Y, In, Ce, Pr, Nd, F, Ir, Mn, Pd, or Fe. In some embodiments, the length Lsoc of the second structure 202 is in a range of 1 nm to 20 nm.

[0048] The spin polarized current J_s in the first structure 201 is converted to charge current J_c by the spin orbit material of the second structure 202/106. This charge current has a direction orthogonal to the direction of the spin polarized current as discussed with reference to Fig. 1. Referring back to Fig. 2A, in various embodiments, metal structures 204 and 205 are provided such that the two metal structures 204 and 205 are adjacent to the spin orbit material of the second structure 202/106, and extend orthogonal (e.g., perpendicular) to the length Lopticai of the first structure 201/104. The two metal structures 204 and 205 are parallel to one another. In some embodiments, the two metal structures comprise one or more of: Cu, Ag, Au, Al, graphene, W, Ni, Co, a-Ta, or Si or a combination of them. In some embodiments, the length Lmetai of the metals 204 and 205 is in a range of 3 nm to 50 nm, and the width (lateral dimension) is in the range of 20 nm to 1000 nm.

[0049] In some embodiments, the critical current density J_c is given by:

where e is the elementary charge, h is the Dirac contact,

is the effective spin Hall angle, eff

and M_s, t_F, and H_K are the saturation magnetization, thickness and effective anisotropy field of the ferrimagnetic material of the first structure 201/104, respectively.

[0050] In some embodiments, the spin orbit material is a SHE (spin Hall effect) material which comprises a spin orbit 2D material that includes one or more of: graphene,

T1S2, WS2, M0S2, TiSe₂, WSe₂, MoSe₂, B2S3, Sb₂S₃, Ta₂S, Re₂S₇, LaCPS₂, LaOAsS₂, ScOBiS₂, GaOBiS₂, AlOBiS₂, LaOSbS₂, BiOBiS₂, YOBiS₂, InOBiS₂, LaOBiSe₂, TiOBiS₂, CeOBiS₂, PrOBiS₂, NdOBiS₂, LaOBiS₂, or SrFBiS₂. In some embodiments, the SHE material comprises spin orbit material which includes one of a 2D material or a 3D material, wherein the 3D material is thinner than the 2D material. In some embodiments, the SHE material comprises a spin orbit material which includes materials that exhibit Rashba- Bychkov effect (e.g., when the magnetization of the ferrimagnetic material is perpendicular along the x-direction relative to the plane z-y of the device).

[0051] In some embodiments, the spin orbit material of the second structure 202/106 includes one of: a 2D material, a 3D material, an AFM material, or an AFM material doped with a doping material, wherein the 3D material is thinner than the 2D material; and wherein the doping material includes one of: Co, Fe, Ni, Mn, Ga, Fe, or Bct-Ru.

[0052] In some embodiments, the 2D materials include one or more of: Mo, S, W, Se,

Graphene, MoS₂, WSe₂, WS₂, or MoSe₂. In some embodiments, the 2D materials include an absorbent which includes one or more of: Cu, Ag, Pt, Bi, Fr, or H absorbents. In some embodiments, the second structure 202/106 comprises a spin orbit material which includes materials that exhibit Rashba-Bychkov effect. In some embodiments, materials that exhibit Rashba-Bychkov effect comprise materials ROCh₂, where‘R’ includes one or more of: La, Ce, Pr, Nd, Sr, Sc, Ga, Al, or In, and where“Ch” is a chalcogenide which includes one or more of: S, Se, or Te.

[0053] In some embodiments, apparatus 200 comprises a third structure adjacent to the second structure 202 such that third structure extends orthogonal to the second structure 202, wherein the third structure comprises metal wires 206 and 207 (e.g., Cu, Ag, Au, Al, graphene, W, Ni, Co, a-Ta, or Si or a combination of them, etc.). In various embodiments, the third structure performs the function of a waveguide for the terahertz signal. In some embodiments, the input of the second waveguide 210 is adjacent to the output section 213 of the second structure 202/106. The output of the second waveguide 203 provides the THz signal. In some embodiments, the second waveguide 210 is a circular metallic waveguide. In some embodiments, second waveguide 210 is a parallel -plate waveguide, coplanar waveguide, or a microstrip transmission line. In some embodiments, the second waveguide 210 is a transmission line which has a small diameter (compared to the diameter or width of the second structure 202) and is used to carry the THz signal 103 as an electromagnetic wave to a destination (such as a processor to process it) as shown with reference to Fig. 12.

[0054] Referring back to Fig. 2A, two conductors 206 and 207 are provided which extend perpendicular to the first (209) and second (210) waveguides. In some embodiments, the two conductors 206 and 207 are like ground conductors to provide a reference point for the signals in the waveguides. In some embodiments, the two conductors 206 and 207 include one or more of: Cu, Ag, Au, Al, graphene, W, Ni, Co, a-Ta, or Si or a combination of them. In various embodiments, the first and second waveguides 209 and 210, and conductors 204, 205, 206, and 207, are embedded in a cladding material 208. In some embodiments, the guiding of the optical wave is enabled by the cladding material 208 having a smaller index of refraction than that of waveguide core 211. In some embodiments, the cladding material 208 includes a polymer such as: polymethyl methacrylate (PMMA), polycarbonate (PC), polytetrafluoroethylene (PTFE), high-density polyethylene (HDPE), and cyclic olefin copolymer (COC). In some embodiments, the lower cladding region 208a and the upper cladding region 208b are formed in two different steps of a fabrication process.

[0055] Here, the first structure 201 of the first waveguide 209 is an optical waveguide

209 and is sometimes described with reference to first structure 209, and the second, terahertz waveguide is described with reference to second structure 210. These structures can be considered as separate waveguides. In some embodiments, these structures might be absent, and either the optical wave or the terahertz wave may not be guided along the z-direction, but rather propagate along a plurality of directions. While the waveguides of Figs. 2A-B are illustrated as rectangular waveguides, they can also be circular, cylindrical, or stripe waveguides such as those shown with reference to Figs. 6A-E.

[0056] Figs. 3A-C illustrate cross-sections 300, 320, and 330, of a super lattice based spin orbit coupling (SOC) material, respectively, according to some embodiments of the disclosure. Cross-section 300 illustrates a version of SOC material of second structure 202/106 that comprises a super lattice of charged and neutral perovskites. For purposes of describing various embodiments, the charged perovskite is considered to be LAO and the neutral perovskite is considered to be STO. However, other embodiments may use different charged and neutral perovskites as listed with reference to Fig. 4.

[0057] Referring back to Fig. 3A, the super lattice comprises LAO 301 and STO 302.

In some embodiments, LAO 301 comprises alternate layers or matched crystals of AIO2 301 a and LaO 30lb. In some embodiments, STO 302 comprises alternate layers or matched crystals of T1O2 602a and SrO 302b. In some embodiments, layer 30 la is adjacent to the ferrimagnetic material of first structure 201/104. In some embodiments, the order of lattices of the super lattice stack can be reversed. For example, STO 302 is adjacent to the ferrimagnetic material of first structure 201/104 while LAO 301 is formed under STO 302. While the embodiment of Fig. 3A illustrates one lattice of LAO followed by one lattice of STO, multiple such lattices can be stacked. In some embodiments, the thickness of the entire lattice along the z-direction is about 6 nm. In some embodiments, the individual lattice layers are 2 to 5 atomic layers thick in the x-direction. In some embodiments, the thickness of the individual lattice layers is between 1 Angstrom (A) and 3A in the x-direction. For example, the thickness of layer 30la along the z-direction is 1A to 3A in thickness.

[0058] Referring now to Fig. 3B, compared to the super lattice of Fig. 3A, here the super lattice of LAO 321 comprises one layer of AIO2 30la and one layer of LaO 30lb, and the super lattice of STO 322 comprises one layer of T1O2 602a and one layer of SrO 302b. In some embodiments, the lattices of 321 and 322 are repeated several times (e.g., 2 to 10 times). In some embodiments, layer 32 la is adjacent to the to the ferrimagnetic material of first structure 201/104. In some embodiments, the order of lattices of the super lattice stack can be reversed. For example, STO 322 is adjacent to the ferrimagnetic material of first structure 201/104 while LAO 321 is formed under STO 302. In some embodiments, the thickness of the entire lattice in the x-direction is about 6 nm.

[0059] Referring now to Fig. 3C, compared to the super lattice of Fig. 3B, here the super lattice comprises an amorphous lattice of a charged perovskite (e.g., LaAlOi) 331 and a lattice of neutral perovskite (e.g., STO) 332. In some embodiments, the lattices 331 and 332 are repeated multiple times (e.g., 2 to 10 times). In some embodiments, lattice 331 is adjacent to the ferrimagnetic material of first structure 201/104. In some embodiments, the order of lattices of the super lattice stack can be reversed. For example, STO 332 is adjacent to the ferrimagnetic material of first structure 201/104 while the amorphous lattice of a charged perovskite is formed under STO 302. In some embodiments, the thickness of the entire lattice is about 6 nm in the x-direction. [0060] In some embodiments, a spin filtering layer (not shown) such as NbFeOi or spin symmetry filter such as MgO, MgAlCfi is added to the super lattice. For example, the spin filtering layer or the spin symmetry filter is the first layer which is adjacent to the ferrimagnetic material of first structure 201/104 followed by any of the super lattices of Figs. 6A-C.

[0061] Fig. 4 illustrates a general perovskite structure 400. A perovskite has a cubic structure with general formula of ABCb. In this cubic structure,‘A’ represents A-site ion (e.g., alkaline earth or rare earth element) which is positioned on the comers of the lattice, Έ’ represents B-site ion (e.g., 3d, 4d, and 5d transition metal elements) on the center of the lattice, and oxide O’ within the lattice forming an angled cube. The periodic table shown in Fig. 4 has elements shaded with three different shades for choices for A, B, and O.

[0062] Figs. 5A-C illustrate an interface 500 of one of the SOC materials of Figs. 3A-

B, 3D view 530 of a charged perovskite 525, and 3D view 540 of a neutral perovskite 540, respectively, according to some embodiments of the disclosure.

[0063] Figs. 6A-C illustrate a hollow-core single clad waveguide 600, hollow-core hybrid-clad waveguide 620, and metal waveguide 630 with thin layer of metamaterial as inner cladding, respectively, in accordance with some embodiments. While the waveguides in Fig. 2A-B are shown as rectangular waveguides, these waveguides can also be circular or cylindrical as shown with reference to Figs. 6A-C. Also the material composition of the circular or cylindrical as shown with reference to Figs. 6A-C are also applicable to the rectangular waveguides of Figs. 2A-B. In some embodiments, when the waveguides of Figs. 2A-B are on-die (e.g., part of system on chip of Fig. 12), then the waveguides can be: circular metallic waveguide, parallel-plate waveguide, a bare metal wire, or a metallic slot waveguide.

[0064] Other configurations are also possible. In some embodiments, when the waveguides of Figs. 2A-B are off-die (e.g., outside of system on chip of Fig. 12), then the waveguides can be one of hollow-core single clad waveguide 600, hollow-core hybrid-clad waveguide 620, and metal waveguide 630 with thin layer of metamaterial as inner cladding. The hollow-core single clad waveguide 600 comprises metal 601 with diameter‘d’ and dielectric/metal thickness‘f . The region of the diameter‘d’ is filled with a ferrimagnetic material for structure 201. The hollow-core hybrid-clad waveguide 620 is a metal waveguide comprising metal 621 with dielectric inner coating 622, where‘D’ is the diameter and‘f is the dielectric thickness. In various embodiments, the region of the diameter‘d’ is filled with a ferrimagnetic material for structure 201. The metal waveguide 630 comprises metal 631 with a thin layer of metamaterial 633 as its inner cladding. The region of the diameter‘d’ is filled with a ferrimagnetic material for structure 201.

[0065] Figs. 6D-G illustrate a coaxial transmission line 640, a stripline 650, a microstrip transmission line 660, and a coplanar waveguide 670, respectively. All of these cross-section shapes can be used as waveguide 210. In some embodiments, coaxial transmission line 640 comprises signal conductor 641 (e.g., to carry the THz signal) embedded in dielectric 643 which is covered by ta ground conductor 642. In some embodiments, stripline 659 comprises signal conductor 651 (e.g., to carry the THz signal) surrounded by dielectric 653, where ground lines 652a/b are over and below dielectric 653. In some embodiments, stripline 660 comprises signal conductor 661 (e.g., to carry the THz signal) fabricated over dielectric 663 which is formed over ground line 662. Co-planar waveguide 670 comprise signal conductor 671 (e.g., to carry the THz signal) fabricated over dielectric 673 where ground lines 672b/c are on either side of the signal conductor 671 and separated by a slot. Another ground return line 672a is formed below dielectric 673.

[0066] Fig. 7 illustrates a flowchart 700 for forming the apparatus of Fig. 2A, in accordance with some embodiments. While the following blocks (or process operations) in the flowchart are arranged in a certain order, the order can be changed. In some embodiments, some blocks can be executed in parallel. At block 701, first waveguide 201 (part of 209) is formed to convert an optical pulse 101 into spin polarized current J_s as discussed with reference to Figs. 1-6. The first waveguide 201 includes core 211. At block 702, structure 202 is formed adjacent to the first waveguide, wherein the structure is to convert the spin polarized current into charge current J_c. At block 703, second waveguide 210 is formed adjacent to the structure 202, wherein the second waveguide 210 is to carry a terahertz electromagnetic wave 103 produced by the charge current Jc in metal conductors 204 and 205.

[0067] Fig. 8 illustrates a SoC (System-on-Chip) 1600 with coupled to THz generation source, according to some embodiments of the disclosure. For purposes of the embodiments, the transistors in various circuits and logic blocks described here are metal oxide semiconductor (MOS) transistors or their derivatives, where the MOS transistors include drain, source, gate, and bulk terminals. The transistors and/or the MOS transistor derivatives also include Tri-Gate and FinFET transistors, Gate All Around Cylindrical Transistors, Tunneling FET (TFET), Square Wire, or Rectangular Ribbon Transistors, ferroelectric FET (FeFETs), or other devices implementing transistor functionality like carbon nanotubes or spintronic devices. MOSFET symmetrical source and drain terminals i.e., are identical terminals and are interchangeably used here. A TFET device, on the other hand, has asymmetric Source and Drain terminals. Those skilled in the art will appreciate that other transistors, for example, Bi-polar junction transistors (BJT PNP/NPN), BiCMOS, CMOS, etc., may be used without departing from the scope of the disclosure.

[0068] Fig. 8 illustrates a block diagram of an embodiment of a mobile device in which flat surface interface connectors could be used. In some embodiments, computing device 1600 represents a mobile computing device, such as a computing tablet, a mobile phone or smart-phone, a wireless-enabled e-reader, or other wireless mobile device. It will be understood that certain components are shown generally, and not all components of such a device are shown in computing device 1600.

[0069] In some embodiments, computing device 1600 includes first processor 1610 which processes the THz signal from block 1690 (e.g., apparatus 200), according to some embodiments discussed. Block 1690 can be on-die or off-die. The various embodiments of the present disclosure may also comprise a network interface within 1670 such as a wireless interface so that a system embodiment may be incorporated into a wireless device, for example, cell phone or personal digital assistant.

[0070] In some embodiments, processor 1610 can include one or more physical devices, such as microprocessors, application processors, microcontrollers, programmable logic devices, or other processing means. The processing operations performed by processor 1610 include the execution of an operating platform or operating system on which applications and/or device functions are executed. The processing operations include operations related to I/O (input/output) with a human user or with other devices, operations related to power management, and/or operations related to connecting the computing device 1600 to another device. The processing operations may also include operations related to audio I/O and/or display I/O.

[0071] In some embodiments, computing device 1600 includes audio subsystem

1620, which represents hardware (e.g., audio hardware and audio circuits) and software (e.g., drivers, codecs) components associated with providing audio functions to the computing device. Audio functions can include speaker and/or headphone output, as well as microphone input. Devices for such functions can be integrated into computing device 1600 or connected to the computing device 1600. In one embodiment, a user interacts with the computing device 1600 by providing audio commands that are received and processed by processor 1610. [0072] In some embodiments, computing device 1600 comprises display subsystem

1630. Display subsystem 1630 represents hardware (e.g., display devices) and software (e.g., drivers) components that provide a visual and/or tactile display for a user to interact with the computing device 1600. Display subsystem 1630 includes display interface 1632, which includes the particular screen or hardware device used to provide a display to a user. In one embodiment, display interface 1632 includes logic separate from processor 1610 to perform at least some processing related to the display. In one embodiment, display subsystem 1630 includes a touch screen (or touch pad) device that provides both output and input to a user.

[0073] In some embodiments, computing device 1600 comprises I/O controller 1640.

I/O controller 1640 represents hardware devices and software components related to interaction with a user. I/O controller 1640 is operable to manage hardware that is part of audio subsystem 1620 and/or display subsystem 1630. Additionally, I/O controller 1640 illustrates a connection point for additional devices that connect to computing device 1600 through which a user might interact with the system. For example, devices that can be attached to the computing device 1600 might include microphone devices, speaker or stereo systems, video systems or other display devices, keyboard or keypad devices, or other I/O devices for use with specific applications such as card readers or other devices.

[0074] As mentioned above, I/O controller 1640 can interact with audio subsystem

1620 and/or display subsystem 1630. For example, input through a microphone or other audio device can provide input or commands for one or more applications or functions of the computing device 1600. Additionally, audio output can be provided instead of, or in addition to display output. In another example, if display subsystem 1630 includes a touch screen, the display device also acts as an input device, which can be at least partially managed by I/O controller 1640. There can also be additional buttons or switches on the computing device 1600 to provide I/O functions managed by I/O controller 1640.

[0075] In some embodiments, I/O controller 1640 manages devices such as accelerometers, cameras, light sensors or other environmental sensors, or other hardware that can be included in the computing device 1600. The input can be part of direct user interaction, as well as providing environmental input to the system to influence its operations (such as filtering for noise, adjusting displays for brightness detection, applying a flash for a camera, or other features).

[0076] In some embodiments, computing device 1600 includes power management

1650 that manages battery power usage, charging of the battery, and features related to power saving operation. Memory subsystem 1660 includes memory devices for storing information in computing device 1600. Memory can include nonvolatile (state does not change if power to the memory device is interrupted) and/or volatile (state is indeterminate if power to the memory device is interrupted) memory devices. Memory subsystem 1660 can store application data, user data, music, photos, documents, or other data, as well as system data (whether long-term or temporary) related to the execution of the applications and functions of the computing device 1600.

[0077] Elements of embodiments are also provided as a machine-readable medium

(e.g., memory 1660) for storing the computer-executable instructions (e.g., instructions to implement any other processes discussed herein). The machine-readable medium (e.g., memory 1660) may include, but is not limited to, flash memory, optical disks, CD-ROMs, DVD ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, phase change memory (PCM), or other types of machine-readable media suitable for storing electronic or computer- executable instructions. For example, embodiments of the disclosure may be downloaded as a computer program (e.g., BIOS) which may be transferred from a remote computer (e.g., a server) to a requesting computer (e.g., a client) by way of data signals via a communication link (e.g., a modem or network connection).

[0078] In some embodiments, computing device 1600 comprises connectivity 1670.

Connectivity 1670 includes hardware devices (e.g., wireless and/or wired connectors and communication hardware) and software components (e.g., drivers, protocol stacks) to enable the computing device 1600 to communicate with external devices. The computing device 1600 could be separate devices, such as other computing devices, wireless access points or base stations, as well as peripherals such as headsets, printers, or other devices.

[0079] Connectivity 1670 can include multiple different types of connectivity. To generalize, the computing device 1600 is illustrated with cellular connectivity 1672 and wireless connectivity 1674. Cellular connectivity 1672 refers generally to cellular network connectivity provided by wireless carriers, such as provided via GSM (global system for mobile communications) or variations or derivatives, CDMA (code division multiple access) or variations or derivatives, TDM (time division multiplexing) or variations or derivatives, or other cellular service standards. Wireless connectivity (or wireless interface) 1674 refers to wireless connectivity that is not cellular and can include personal area networks (such as Bluetooth, Near Field, etc.), local area networks (such as Wi-Fi), and/or wide area networks (such as WiMax), or other wireless communication.

[0080] In some embodiments, computing device 1600 comprises peripheral connections 1680. Peripheral connections 1680 include hardware interfaces and connectors, as well as software components (e.g., drivers, protocol stacks) to make peripheral connections. It will be understood that the computing device 1600 could both be a peripheral device ("to" 1682) to other computing devices, as well as have peripheral devices ("from" 1684) connected to it. The computing device 1600 commonly has a "docking" connector to connect to other computing devices for purposes such as managing (e.g., downloading and/or uploading, changing, synchronizing) content on computing device 1600. Additionally, a docking connector can allow computing device 1600 to connect to certain peripherals that allow the computing device 1600 to control content output, for example, to audiovisual or other systems.

[0081] In addition to a proprietary docking connector or other proprietary connection hardware, the computing device 1600 can make peripheral connections 1680 via common or standards-based connectors. Common types can include a Universal Serial Bus (USB) connector (which can include any of a number of different hardware interfaces), DisplayPort including MiniDisplayPort (MDP), High Definition Multimedia Interface (HDMI), Firewire, or other types.

[0082] Reference in the specification to "an embodiment," "one embodiment," "some embodiments," or "other embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments. The various appearances of "an embodiment," "one embodiment," or "some embodiments" are not necessarily all referring to the same embodiments. If the specification states a component, feature, structure, or characteristic "may," "might," or "could" be included, that particular component, feature, structure, or characteristic is not required to be included. If the specification or claim refers to "a" or "an" element, that does not mean there is only one of the elements. If the specification or claims refer to "an additional" element, that does not preclude there being more than one of the additional element.

[0083] Furthermore, the particular features, structures, functions, or characteristics may be combined in any suitable manner in one or more embodiments. For example, a first embodiment may be combined with a second embodiment anywhere the particular features, structures, functions, or characteristics associated with the two embodiments are not mutually exclusive.

[0084] While the disclosure has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations of such embodiments will be apparent to those of ordinary skill in the art in light of the foregoing description. The embodiments of the disclosure are intended to embrace all such alternatives, modifications, and variations as to fall within the broad scope of the appended claims.

[0085] In addition, well known power/ground connections to integrated circuit (IC) chips and other components may or may not be shown within the presented figures, for simplicity of illustration and discussion, and so as not to obscure the disclosure. Further, arrangements may be shown in block diagram form in order to avoid obscuring the disclosure, and also in view of the fact that specifics with respect to implementation of such block diagram arrangements are highly dependent upon the platform within which the present disclosure is to be implemented (i.e., such specifics should be well within purview of one skilled in the art). Where specific details (e.g., circuits) are set forth in order to describe example embodiments of the disclosure, it should be apparent to one skilled in the art that the disclosure can be practiced without, or with variation of, these specific details. The description is thus to be regarded as illustrative instead of limiting.

[0086] An abstract is provided that will allow the reader to ascertain the nature and gist of the technical disclosure. The abstract is submitted with the understanding that it will not be used to limit the scope or meaning of the claims. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.

Claims

CLAIMS We claim:

1. An apparatus comprising:

a first waveguide having an input, an output, and a body between the input and output, wherein the body is longer than the input or output, wherein the first waveguide comprises:

a first structure comprising a ferrimagnetic material, wherein the first structure has an input, an output, and a body, wherein the input of the first structure is same as the input of the first waveguide; and

a second structure adjacent to the first structure, wherein the second structure comprises a spin orbit material, wherein the second structure has an input, an output, and a body, wherein the input of the second structure is adjacent to the output of the first structure, wherein the output of the second structure is same as the output of the first waveguide, and wherein the bodies of the first and second structures together equal the body of the first waveguide; and

a second waveguide adjacent to the first waveguide.

2. The apparatus of claim 1, wherein the second waveguide has an input substantially larger than the input of the first waveguide.

3. The apparatus of claim 1, wherein the second waveguide has an input substantially

smaller than the input of the first waveguide.

4. The apparatus of claim 1, wherein the ferrimagnetic material includes one or more of: Y, Fe, Al, Co, Ni, Mg, Zn, Ba, Rb, S, or O.

5. The apparatus of claim 1, wherein the spin orbit material comprises a super lattice of a neutral perovskite and a charged perovskite.

6. The apparatus of claim 5, wherein the neutral perovskite comprises a group 2 element and oxygen, and wherein the charged perovskite comprises one of a group 3d, 4d, or 5d transition metal and oxygen, or wherein the neutral perovskite comprises one or both of: Sr and O; or Ti and O.

7. The apparatus of claim 5, wherein the charged perovskite comprises one or both of: Al and O; or La and O.

8. The apparatus of claim 1, wherein the spin orbit material comprises one or more of: b- Tantalum (b-Ta), Ta, b-Tungsten (b-W), W, Platinum (Pt), Copper (Cu) doped with elements including on of Iridium, Bismuth or elements of 3d, 4d, 5d and 4f, 5f periodic groups, Ti, S, W, Mo, Se, B, Sb, Re, La, C, P, La, As, Sc, O, Bi, Ga, Al, Y, In, Ce, Pr,

Nd, F, Ir, Mn, Pd, or Fe.

9. The apparatus according to any one of claims 1 to 8 comprises a third structure adjacent to the second structure such that third structure extends orthogonal to the second structure, wherein the third structure comprises metal.

10. The apparatus of claim 9 comprises a fourth structure adjacent to the second structure such that fourth structure extends orthogonal to the second structure, wherein the fourth structure comprises metal, and wherein the fourth structure is adjacent to a first side of the second structure while the third structure is adjacent to a second side of the second structure, wherein the second side is parallel to the first side.

11. The apparatus of claim 10, wherein the metal of the third or fourth structures include one or more of: Cu, Co, a-Ta, Al, Si, or Ni.

12. The apparatus of claim 10 comprises a fifth structure comprising metal and a sixth

structure comprises metal, wherein:

the fifth and sixth structures extend parallel to the first and second waveguides;

the fifth and sixth structures are positioned on either side of the first and second waveguides; and

the first and second waveguides, third and fourth structures, and fifth and sixth structures are embedded in a cladding material.

13. The apparatus of claim 12, wherein the cladding material includes one of: polymethyl methacrylate (PMMA), polycarbonate (PC), polytetrafluoroethylene (PTFE), high-density polyethylene (HDPE), or cyclic olefin copolymer (COC).

14. The apparatus according to any one of claims 1 to 8, wherein spin orbit material includes one of: a 2D material, a 3D material, an AFM material, or an AFM material doped with a doping material, wherein the 3D material is thinner than the 2D material; and wherein the doping material includes one of: Co, Fe, Ni, Mn, Ga, Fe, or Bct-Ru.

15. The apparatus of claim 1, wherein the first structure includes one of: hollow-core single clad waveguide, hollow-core hybrid-clad waveguide, metal waveguide with cladding; and wherein the second waveguide comprises one of: a coaxial transmission line, a stripline, a microstrip transmission line, or a coplanar waveguide.

16. An apparatus comprising:

a first waveguide to convert an optical pulse into spin current;

a structure adjacent to the first waveguide, wherein the structure is to convert the spin current into charge current; and

a second waveguide adjacent to the structure, wherein the second waveguide is to carry an electromagnetic wave produced from the charge current.

17. The apparatus of claim 16, wherein the first waveguide comprises a ferrimagnetic

material, and wherein the structure comprises a spin orbit material.

18. The apparatus of claim 17, wherein the ferrimagnetic material includes one or more of: Y, Fe, Al, Co, Ni, Mg, Zn, Ba, Rb, S, or O.

19. The apparatus of claim 17, wherein the spin orbit material comprises a super lattice of a neutral perovskite and a charged perovskite, wherein the neutral perovskite comprises a group 2 element and oxygen, and wherein the charged perovskite comprises one of a group 3d, 4d, or 5d transition metal and oxygen, or wherein the neutral perovskite comprises one or both of: Sr and O; or Ti and O, and wherein the charged perovskite comprises one or both of: Al and O; or La and O.

20. The apparatus of claim 17, wherein the spin orbit material comprises one or more of: b- Tantalum (b-Ta), Ta, b-Tungsten (b-W), W, Platinum (Pt), Copper (Cu) doped with elements including on of Iridium, Bismuth or elements of 3d, 4d, 5d and 4f, 5f periodic groups, Ti, S, W, Mo, Se, B, Sb, Re, La, C, P, La, As, Sc, O, Bi, Ga, Al, Y, In, Ce, Pr, Nd, F, Ir, Mn, Pd, or Fe.

21. A method comprising:

forming a first waveguide to convert an optical pulse into spin current;

forming a structure adjacent to the first waveguide, wherein the structure is to convert the spin current into charge current; and

forming a second waveguide adjacent to the second waveguide, wherein the second waveguide is to carry an electromagnetic wave produced from the charge current.

22. The method of claim 21, wherein:

the first waveguide comprises a ferrimagnetic material, and wherein the structure comprises a spin orbit material;

the ferrimagnetic material includes one or more of: Y, Fe, Al, Co, Ni, Mg, Zn, Ba, Rb, S, or O; and

the spin orbit material comprises a super lattice of a neutral perovskite and a charged perovskite, wherein the neutral perovskite comprises a group 2 element and oxygen, wherein the charged perovskite comprises one of a group 3d, 4d, or 5d transition metal and oxygen, or wherein the neutral perovskite comprises one or both of: Sr and O; or Ti and O, and wherein the charged perovskite comprises one or both of: Al and O; or La and O; or

the spin orbit material comprises one or more of: b-Tantalum (b-Ta), Ta, b-Tungsten (b-W), W, Platinum (Pt), Copper (Cu) doped with elements including on of Iridium, Bismuth or elements of 3d, 4d, 5d and 4f, 5f periodic groups, Ti, S, W, Mo, Se, B, Sb, Re, La, C, P, La, As, Sc, O, Bi, Ga, Al, Y, In, Ce, Pr, Nd, F, Ir, Mn, Pd, or Fe.

23. A system comprising:

a memory;

a processor coupled to the memory, the processor comprising an apparatus according to any one of claims 1 through 15, or an apparatus according to any one of claims 16 through 20; and

a wireless interface to allow the processor to communicate with another device.