Programmable Photonic Waveguide

Abstract

Methods, devices, and systems are provided for managing a programmable photonic waveguide. In one aspect, the method includes varying respective local electric fields across a plurality of regions of a waveguide core of a waveguide structure of a programmable photonic waveguide to cause corresponding local variations in at least one of a refractive index or a nonlinear susceptibility of the waveguide core, and programming an optical signal by coupling the optical signal passing through the waveguide core with the corresponding local variations in at least one of the refractive index or the nonlinear susceptibility of the waveguide core.

Description

Technical Field

[0001] The present disclosure generally relates to integrated photonics, and more particularly to programmable photonic waveguides.

Background Art

[0002] Integrated photonics, which is a field of manipulating light in a miniaturized on-chip setting, has the potential to reduce device size, significantly lower energy costs, and increase device speed for computing and communication applications. However, this potential is technically difficult to realize due to relatively large process variations in the manufacturing process, which may lead to a significant degradation in device performance. This problem is further exacerbated by the long turnaround time of the manufacturing process, often resulting in prohibitively expensive and time-consuming research and development cycles.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The present disclosure describes a method, apparatus, and system for implementing a programmable photonic waveguide.

Means for Solving the Problems

[0004] One aspect of the present disclosure is a programmable system, including a programmable device extending in a plane, the programmable device comprising a waveguide structure including a pair of planar electrode layers extending parallel to each other, a core layer, and a pair of clad layers on opposite sides of the core layer, the core layer being between the planar electrode layers and the waveguide structure including a photoconductive material, a power source electrically connected to the planar electrode layers and configured to apply a voltage across the waveguide structure during operation of the programmable system, a light source configured to generate illumination at a wavelength sufficient to change the conductivity of the photoconductive material, a spatial light controller configured to receive illumination from the light source and illuminate the photoconductive material with patterned illumination sufficient to locally change the conductivity of the photoconductive material while a voltage is applied across the waveguide structure, and an optical signal source configured to direct an optical signal toward an end of the waveguide structure to couple the optical signal into the core layer while the photoconductive material is illuminated with the patterned illumination and a voltage is applied across the waveguide structure.

[0005] In some embodiments, the patterned illumination is configured to locally change the conductivity of the photoconductive material sufficient to cause a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the core layer during operation of the programmable system.

[0006] In some embodiments, the patterned illumination to the photoconductive material and the voltage applied across the waveguide structure generate a local variation of the electric field across a plurality of regions of the core layer to cause a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the core layer.

[0007] In some embodiments, the corresponding local variation of the refractive index of the core layer is in the range from 10 -4 to greater than 0.1.

[0008] In some embodiments, the corresponding local variations in the second-order nonlinear susceptibility of the core layer are in the range from 1 pm / V to beyond 10 3 pm / V.

[0009] In some embodiments, the core layer comprises a photoconductive material.

[0010] In some embodiments, at least one of the planar electrode layers is configured as at least a part of the cladding layer.

[0011] In some embodiments, the core layer is directly adjacent to a pair of planar electrode layers that are between a pair of cladding layers.

[0012] In some embodiments, the photoconductive material is disposed in a layer different from the core layer.

[0013] In some embodiments, the layer containing the photoconductive material is above the core layer and between the upper planar electrode layer of the planar electrode layers and the upper cladding layer of the cladding layers.

[0014] In some embodiments, the spatial light controller includes an optical deflection device configured to individually deflect respective illumination spots of illumination from a light source to a plurality of different corresponding regions on the upper surface of a programmable device to generate patterned illumination.

[0015] In some embodiments, the optical polarization device includes a digital micromirror device (DMD).

[0016] In some embodiments, the spatial light controller includes an optical scanner configured to sequentially scan illumination spots of illumination from a light source across a plurality of different corresponding regions on the upper surface of a programmable device to generate patterned illumination.

[0017] In some embodiments, the optical scanner includes a raster optical scanning device.

[0018] In some embodiments, the spatial light controller includes a spatial light modulator (SLM) having a plurality of elements configured to modulate illumination from a light source so as to diffract the illumination to generate patterned illumination in a plurality of different corresponding regions on the upper surface of a programmable device.

[0019] In some embodiments, the spatial light controller includes a transmissive SLM between the light source and the programmable device.

[0020] In some embodiments, the programmable system further includes a controller coupled to at least one of a power supply, a light source, a spatial light controller, or an optical signal source.

[0021] In some embodiments, the controller is configured to generate at least one control signal based on at least one target optical signal, wherein the at least one control signal corresponds to at least one of a two-dimensional (2D) refractive index profile or a 2D nonlinear susceptibility profile in the core layer, and to transmit the at least one control signal to at least one of a power supply, a light source, a spatial light controller, or an optical signal source.

[0022] In some embodiments, the at least one control signal includes at least one of a first control signal to the light source to generate corresponding illumination, a second control signal to the spatial light controller to control the corresponding illumination to generate corresponding patterned illumination on the photoconductive material, a third control signal to the power supply to generate a corresponding voltage applied across the waveguide structure, or a fourth control signal to the optical signal source to generate a corresponding input optical signal.

[0023] In some embodiments, the programmable system further includes an optical receiver configured to receive an output optical signal coupled from the waveguide structure.

[0024] In some embodiments, the photoconductive material comprises at least one of silicon-rich silicon nitride (SRN), silicon nitride, amorphous silicon, crystalline silicon, liquid crystal, barium titanate, silicon carbide, aluminum nitride, or lithium niobate.

[0025] Another aspect of the present disclosure features a programmable device that includes a waveguide structure that extends in a plane and has a core layer and a pair of cladding layers on opposite sides of the core layer, and a pair of planar electrode layers that extend parallel to each other, with the core layer between the planar electrode layers, and a photoconductive layer that includes a photoconductive material. In operation of the programmable device, a voltage is applied across the waveguide structure via the planar electrode layers, and a patterned illumination of light is projected onto individual regions of the photoconductive layer to locally vary the conductivity of the photoconductive material within the photoconductive layer so as to cause a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the core layer while the voltage is applied across the waveguide structure, and an optical signal is coupled into the core layer and propagates through the core layer with a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility.

[0026] In some embodiments, the core layer comprises the photoconductive layer.

[0027] In some embodiments, at least one of the planar electrode layers is configured as at least a portion of the cladding layer.

[0028] In some embodiments, the core layer is directly adjacent to a pair of planar electrode layers that are between the pair of cladding layers.

[0029] In some embodiments, the photoconductive layer is different from the core layer.

[0030] In some embodiments, the photoconductive layer is above the core layer and between an upper planar electrode layer of the planar electrode layers and an upper cladding layer of the cladding layers.

[0031] In some embodiments, the voltage applied across the patterned illumination and waveguide structure to the optical waveguide layer creates local variations in the electric field across multiple different corresponding regions of the core layer such that a corresponding local variation in at least one of the refractive index or the non - linear susceptibility of the core layer is caused.

[0032] In some embodiments, the optically conductive material comprises at least one of silicon - rich nitride (SRN), silicon nitride, amorphous silicon, crystalline silicon, liquid crystal, barium titanate, silicon carbide, aluminum nitride, or lithium niobate.

[0033] Another aspect of the present disclosure features a programmable device including a waveguide structure having a pair of a core layer and a cladding layer on the opposite side of the core layer, and first and second planar electrode layers extending parallel to each other, wherein the waveguide structure is between the first planar electrode layer and the second planar electrode layer. The first planar electrode layer includes a plurality of pixelated electrodes insulated from each other, each of the pixelated electrodes being individually controlled to receive a respective voltage, and the second planar electrode layer is commonly coupled to ground. In operation of the programmable device, individual voltages are applied to the plurality of pixelated electrodes to create a locally varying electric field across the core layer such that a corresponding local variation in at least one of the refractive index or the non - linear susceptibility of the core layer is caused, and an optical signal is coupled into the core layer and propagates through the core layer with a corresponding local variation in at least one of the refractive index or the non - linear susceptibility.

[0034] Another aspect of the present disclosure is a programmable device comprising a one-dimensional waveguide structure extending along a longitudinal direction and having a waveguide core and a cladding layer surrounding the waveguide core, a photoconductive layer including a photoconductive material and extending along the longitudinal direction, and first and second planar electrode layers extending parallel to each other along the longitudinal direction, wherein the waveguide structure is disposed between the first planar electrode layer and the second planar electrode layer. In the operation of the programmable device, a voltage is applied across the waveguide structure via the planar electrode layers, and while the voltage is applied across the waveguide structure, a patterned illumination of light is projected onto a plurality of different corresponding regions of the photoconductive layer along the longitudinal direction to locally change the conductivity of the photoconductive material in the photoconductive layer so as to cause a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the waveguide core along the longitudinal direction, an optical signal is coupled to the waveguide core, and propagates through the waveguide core with a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility along the longitudinal direction.

[0035] Another aspect of the present disclosure is a method of managing a programmable device, the method comprising illuminating light onto the programmable device to generate a patterned illumination of light on the photoconductive layer of the programmable device so as to locally change the conductivity of the photoconductive material in the photoconductive layer, the programmable device including a waveguide structure extending in a plane and having a core layer and a pair of cladding layers on opposite sides of the core layer; applying a voltage across the waveguide structure via a pair of planar electrode layers of the programmable device while illuminating light onto the programmable device so as to cause a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the core layer; and programming an optical signal by coupling the optical signal passing through the core layer with a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the core layer.

[0036] In some embodiments, the core layer includes the photoconductive layer.

[0037] In some embodiments, the optical waveguide layer is disposed between an upper planar electrode layer of the planar electrode layers and an upper cladding layer of the cladding layers, and light is illuminated onto the optical waveguide layer through the upper planar electrode layer.

[0038] In some embodiments, the step of illuminating light on the programmable device includes individually deflecting respective illumination spots of light to a plurality of different corresponding regions on the upper surface of the programmable device to generate patterned illumination of the light.

[0039] In some embodiments, the step of illuminating light on the programmable device includes sequentially scanning illumination spots of light across a plurality of different corresponding regions on the upper surface of the programmable device to generate patterned illumination.

[0040] In some embodiments, the step of illuminating light on the programmable device includes modulating a plurality of elements of a spatial light modulator (SLM) to diffract the light to generate patterned illumination in a plurality of different corresponding regions on the upper surface of the programmable device.

[0041] In some embodiments, the method further includes generating at least one control signal based on at least one target optical signal, wherein the at least one control signal corresponds to at least one of a two-dimensional (2D) refractive index profile or a 2D nonlinear susceptibility profile in the core layer, and using the control signal to control at least one of illumination of light on the programmable device, a voltage applied across the waveguide structure, or an optical signal coupled through the core layer.

[0042] In some embodiments, the method further includes receiving a coupled and programmed optical signal from a core layer and adjusting a control signal based on a result of comparing the programmed optical signal with at least one target optical signal.

[0043] Another aspect of the present disclosure features a method of managing a programmable device, including varying respective local electric fields across a plurality of regions of a waveguide core of a waveguide structure within the programmable device to cause corresponding local variations in at least one of a refractive index or a nonlinear susceptibility of the waveguide core, and programming an optical signal by coupling the optical signal passing through the waveguide core with the corresponding local variations in at least one of the refractive index or the nonlinear susceptibility of the waveguide core.

[0044] In some embodiments, varying respective local electric fields across a plurality of regions of a waveguide core includes illuminating light on a waveguide structure of the programmable device to generate a patterned illumination of light on a photoconductive material within the waveguide structure so as to locally vary the conductivity of the photoconductive material, and applying a voltage across the waveguide structure to cause a change in respective local electric fields across the plurality of regions of the waveguide core while illuminating light on the waveguide structure, wherein the patterned illumination of light on the photoconductive material corresponds to the plurality of regions of the waveguide core.

[0045] In some embodiments, the waveguide structure is between a first planar electrode layer and a second planar electrode layer, the first planar electrode layer includes a plurality of pixelated electrodes configured to receive respective voltages, and the second planar electrode layer is commonly coupled to ground. In some embodiments, the step of varying each local electric field across a plurality of regions of the waveguide core is the step of varying each voltage coupled to a plurality of pixelated electrodes to vary each local electric field across a plurality of regions of the waveguide core, the plurality of pixelated electrodes corresponding to the plurality of regions of the waveguide core, and includes the step.

[0046] In some embodiments, the waveguide structure includes one of a one-dimensional (1D) waveguide extending along a longitudinal direction or a two-dimensional (2D) waveguide extending in a plane.

[0047] Another aspect of the present disclosure features a method of manufacturing the programmable system described herein.

[0048] Another aspect of the present disclosure features a method of manufacturing the programmable device described herein.

[0049] The implementation forms described in this specification can provide various technical benefits and advantages. First, this technique can address the problems of the manufacturing process of conventional integrated photonic devices. Here, a programmable photonic waveguide can be manufactured once, and the function of the photonic waveguide can be programmed afterwards, which is similar to the way an integrated electronic circuit can undertake different or new functions by uploading a software program. Therefore, this technique can reduce or eliminate large process variations, shorten the manufacturing time, and improve the manufacturing yield and device performance. Second, the programmable photonic waveguide is composed of multiple stacked layers that can be easily manufactured by conventional deposition techniques (such as metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE)) without manufacturing complex microstructures or nanostructures in the waveguide (for example, using nanolithography). Therefore, it can consume less time and labor, and can be more reliable and more repeatable. Third, for example, by generating different patterned illuminations on the optical conduction layer corresponding to the waveguide core, any desired number of regions within the waveguide core of the photonic waveguide can be virtually formed or changed without actual manufacturing. Fourth, the programmable photonic waveguide can be reprogrammed any number of times (for example, until it wears out like an electronic circuit). In contrast, devices using phase change materials have a finite number (for example, thousands) of rewrite cycles before the phase change materials are permanently damaged. Fifth, this technique can significantly increase the degree of control over light in the programmable photonic waveguide, for example, the number of parameters in the photonic waveguide, compared to other techniques using, for example, basic unit cells of phase change materials or optical phase shifters. Sixth, this technique enables changing the refractive index and nonlinear susceptibility of the photonic waveguide, which are the basic physical properties of any given optical medium that determine how light moves through the photonic waveguide.Therefore, the present technique can integrate several optical devices within a single chip to implement several corresponding optical functions, which can reduce the size of the photonic system and enhance its functionality. Seventhly, the present technique can be applied to any suitable device, such as a one-dimensional (1D) device, a two-dimensional (2D) device, or a three-dimensional (3D) device, any suitable system, or any suitable application, such as machine learning, optical computing, and telecommunication.

[0050] Details of one or more of the disclosed implementations are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims.

Brief Description of the Drawings

[0051]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 5

Figure 6A

Figure 6B

Best Mode for Carrying Out the Invention

[0052] Like reference numerals and designations in the various drawings indicate like elements. It should also be understood that the various illustrative implementations shown in the figures are merely illustrative representations and are not necessarily drawn to scale.

[0053] Implementations of the present disclosure provide methods, devices, systems, and techniques for managing programmable photonic waveguides to control the wave dynamics of light traveling within the photonic waveguides.

[0054] For example, as described in further detail in FIG. 1, a programmable photonic waveguide can be controlled (or programmed) by varying respective local electric fields across the waveguide core of the photonic waveguide to cause corresponding local variations in at least one of the refractive index or the nonlinear susceptibility of the waveguide core. When an optical signal (e.g., a laser pulse) is coupled into the waveguide core with corresponding local variations in at least one of the refractive index or the nonlinear susceptibility, the optical signal can be programmed to a target optical signal at the output of the waveguide core. Thus, the photonic waveguide can be programmed to obtain a target optical signal without changing the physical structure of the photonic waveguide.

[0055] In some implementations, as described in more detail in FIGS. 2, 3, and 4A - 4B, a programmable photonic waveguide can include an optical conduction layer within the waveguide structure. The optical conduction layer can be within the waveguide core as described in FIG. 2 or FIG. 3, or within a layer between the electrode layer and the cladding layer as described in FIGS. 4A - 4B. The spatial light controller can be configured to direct patterned illumination over multiple different corresponding regions of the optical conduction layer to locally vary the conductivity of an optically conductive material (or photoresist) within the optical conduction layer. In some examples, the patterned illumination refers to an optical pattern that has illumination over selected regions of a surface (or layer) and no illumination over other regions of the surface (or layer). In some examples, the patterned illumination refers to an optical pattern that has an optical intensity higher than a threshold intensity over selected regions of a surface (or layer) and an optical intensity lower than the threshold intensity over other regions of the surface (or layer). In some examples, the patterned illumination refers to polarization variations or spectral variations in different regions across a surface (or layer).

[0056] While the patterned illumination is over multiple different corresponding regions of the optical conduction layer, a voltage is applied across the photonic waveguide to vary each local electric field across the waveguide core of the photonic waveguide, for example, to cause corresponding local variations in at least one of the refractive index or the nonlinear susceptibility of the waveguide core due to, e.g., the DC Kerr effect or the electric - field - induced second - harmonic (EFISH) effect. The spatial light controller can include an optical deflection device such as a DMD as described in FIG. 2, a scanner such as a raster light scanning device as described in FIG. 3, or a spatial light modulator (SLM).

[0057] In some implementations, as described in more detail in FIG. 5, a programmable photonic waveguide can include a pixelated electrode layer on top of a waveguide structure having a waveguide core between cladding phases. Each pixelated electrode within the pixelated electrode layer can be configured to receive a respective voltage. Each respective voltage to the pixelated electrodes can be controlled to vary respective local electric fields across different regions of the waveguide core to cause corresponding local variations in at least one of the refractive index or the nonlinear susceptibility of the waveguide core.

[0058] Principle FIG. 1 shows the operating principle of an exemplary programmable photonic waveguide 100. As an example, the photonic waveguide 100 will be described as a 2D planar waveguide extending in a plane, for example, the XZ plane. Light traveling within the photonic waveguide 100 is confined in a perpendicular dimension perpendicular to the plane, for example, the Y dimension.

[0059] The photonic waveguide 100 can include a waveguide core between pairs of cladding layers. For example, an input optical signal 101 having an electric field represented as E(x,z) is coupled into the waveguide core from a first end 102 of the photonic waveguide 100 and travels within the photonic waveguide 100 and can be coupled out as an output optical signal 103 having an electric field represented as E(x,z) from a second opposite end 104 of the photonic waveguide 100. The characteristics of the output optical signal 103 are determined based on the characteristics of the input optical signal 101 and the characteristics of the photonic waveguide 100. in For example, along the Y dimension, a voltage can be applied across the photonic waveguide 100, for example, via a pair of planar electrode layers, to generate a direct current (DC) electric field E across the waveguide core. Based on electro-optic modulation, the electric field can then induce a change in the refractive index or the nonlinear susceptibility of the material of the waveguide core of the photonic waveguide 100. out

[0060] DC

[0061] ​​​Refractive index n of the waveguide core material 0 can have a linear change. According to the DC Kerr effect, in one example, the linear change Δn in the refractive index is Δn = 6χ (3) E DC 2 / n 0 (1) expressed as, where χ (3) is the third-order nonlinear susceptibility of the waveguide core material, and E DC is the electric field applied across the waveguide core.

[0062] The refractive index n of the waveguide core material 0 can also experience a nonlinear change. According to the electric-field-induced second-harmonic (EFISH) effect, in one example, the second-order nonlinear susceptibility χ (2) is χ (2) = 3χ (3) E DC (2) can be expressed as.

[0063] Therefore, by configuring the waveguide core material (e.g., χ (3) ) and the electric field E DC across the waveguide core, the change Δn in the refractive index and / or the second-order nonlinear susceptibility χ (2) can be controlled. For example, if the waveguide core material has a larger third-order nonlinear susceptibility χ (3) and / or a larger breakdown electric field E Breakdown , the change Δn in the refractive index and / or the second-order nonlinear susceptibility χ (2) can be larger. Additionally, the change Δn in the refractive index and the second-order nonlinear susceptibility χ (2) can change together with each other.

[0064] In one example, silicon has a χ -19 m 2 V -2 of and an E (3) of 40 V / μm. Therefore, silicon has a Breakdown of 2×10 -4The maximum refractive index change Δn and the maximum nonlinear second-order susceptibility χ of 40 pm / V (2) can be had. In another example, silicon-rich silicon nitride (SRN) has 2.5×10 -19 m 2 V -2 for χ (3) and E ranging from 400 V / μm to 1200 V / μm Breakdown . Thus, SRN can have a maximum refractive index change Δn in the range from 0.02 to 0.2, which can be two or three orders of magnitude larger than the refractive index change of silicon. SRN can also have a maximum nonlinear second-order susceptibility χ (2) in the range from 400 pm / V to 1200 pm / V, which can be one or two orders of magnitude larger than the maximum nonlinear second-order susceptibility of silicon.

[0065] Since the refractive index and the nonlinear susceptibility are fundamental physical properties of any given optical medium, programmable photonic devices such as photonic waveguides can be achieved by using an appropriate material (e.g., SRN) for the waveguide core and can be controlled by an appropriate electric field across the waveguide core.

[0066] When a local electric field E DC (x,z) is applied across a plurality of regions 106 of the waveguide core in a plane, e.g., as shown in FIG. 1, each region of the waveguide core can have a corresponding local electric field E DC (x,z) applied thereto to cause a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility. In this way, an optical signal passing through the waveguide core can be locally programmed or manipulated into a target signal having desired properties or characteristics.

[0067] In some implementations, as described in more detail in FIG. 5, a pixelated electrode layer including an array of pixelated electrodes can be formed on top of the photonic waveguide. The array of pixelated electrodes can be physically fabricated (e.g., by photolithography), which can also define the resolution of the programmable photonic waveguide. Each pixelated electrode within the pixelated electrode layer can be configured to receive a respective voltage V DC (x,z). The respective voltages to the pixelated electrodes can be controlled to vary the respective local electric fields E DC (x,z) across different regions of the waveguide core in order to cause corresponding local variations in at least one of the refractive index or the nonlinear susceptibility of the waveguide core.

[0068] In some implementations, a plurality of regions 106 of the waveguide core can be defined virtually (and optionally dynamically) by the profile of the local electric field. The local electric field can be obtained, for example, by patterned illumination of light onto a photoconductive layer within the photonic waveguide, as shown in FIGS. 2, 3, or 4A - 4B. The wavelength of the light can be selected to vary the conductivity of the photoconductive material within the photoconductive layer. The patterned illumination can correspond to different regions of the photoconductive layer that can correspond to the plurality of regions 106 of the waveguide core.

[0069] When there is no illumination on the region of the photoconductive layer, there is no change or almost no change in the refractive indices of the photoconductive material and the photoresist within the region. In contrast, when there is an illumination spot on the region of the photoconductive layer, the conductivity of the photoconductive material within the region may become greater, and thus the refractive index of the photoconductive material within the region may become smaller, and the photoresist of the region may become smaller. While there is patterned illumination on different regions of the photoconductive layer to cause local variations in the refractive index or photoresist, a voltage is applied across the photonic waveguide, thus generating respective local electric fields across the waveguide core of the photonic waveguide, which can thereby cause corresponding local variations in at least one of the refractive index or the nonlinear susceptibility of the waveguide core. Therefore, a photoconductive material having high photoconductivity can increase the corresponding local variations in at least one of the refractive index or the nonlinear susceptibility of the waveguide core.

[0070] In some implementations, the photoconductive material is selected to have low loss, high breakdown electric field, high χ(3) nonlinearity, and / or high photoconductivity. In some examples, the photoconductive material includes at least one of silicon-rich silicon nitride (SRN), silicon nitride, silicon carbide, amorphous silicon, crystalline silicon, liquid crystal, barium titanate, or lithium niobate.

[0071] Exemplary Programmable Waveguide Systems and Devices FIG. 2 is a schematic diagram of an exemplary system 200 including an exemplary programmable photonic planar waveguide 210.

[0072] Similar to the photonic waveguide 100 of FIG. 1, the photonic planar waveguide 210 extends in a plane (e.g., the XZ plane). The photonic planar waveguide 210 includes photonic components and electronic components. The photonic components include a core layer (or waveguide core) 212 and a pair of cladding layers 214a, 214b on opposite sides of the core layer 212, which collectively form a photonic 2D slab waveguide capable of confining light within the vertical dimension (e.g., the Y dimension). The material of the core layer 212 has a refractive index higher than that of the materials of the cladding layers 214a, 214b such that light can be confined within the core layer 212 by total internal reflection and travel within the core layer 212.

[0073] The electrical components include electrodes formed at the outermost ends of the photonic planar waveguide 210, e.g., upper planar electrode layers 216a and lower planar electrode layers 216b on the upper cladding layer 214a and the lower cladding layer 214b, respectively, along the vertical dimension. The planar electrode layers 216a, 216b are electrically coupled to a power source 240, e.g., a voltage source such as a battery or a voltage generator, or a current source. An electrical DC voltage V can be applied across the planar electrode layers 216a, 216b to generate a DC electric field across the core layer 212.

[0074] As shown in FIG. 1, the photonic planar waveguide 210 can be a multilayer structure having a stack of planar layers including the core layer 212, the cladding layers 214a, 214b, and the planar electrode layers 216a, 216b. The multilayer structure can be fabricated by metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), atomic layer deposition (ALD), physical vapor deposition (PVD), chemical vapor deposition (CVD), or any other deposition method within a vacuum chamber.

[0075] System 200 can include an optical signal source 202 configured to provide an input optical signal 201. For example, the optical signal source 202 can be a pulsed laser source, and the input optical signal 201 can include one or more laser pulses. The input optical signal 201 is coupled to the core layer 212 through an end of the photonic planar waveguide 210, propagates through the core layer 212, and can be coupled from the core layer 212 to an output optical signal 203. The output optical signal 203 can be received by an optical receiver 204. The input optical signal 201 can be at any desired wavelength, for example, a wavelength from 500 nm to 5000 nm. In some examples, the input optical signal 201 can first be spatially modulated using a spatial light modulator and / or temporally / frequency-domain modulated using an electro-optic modulator. In some examples, it can include one or more laser pulses each having a duration, for example, a duration of nanoseconds (ns), picoseconds (ps), or femtoseconds (fs). The input optical signal 201 can have a modulation frequency, for example, a modulation frequency of about 100s MHz. In some examples, the input optical signal includes continuous wave (CW) light. As described above, the characteristics or properties of the output optical signal 203 are determined based on the characteristics or properties of the input optical signal 201 and the characteristics or properties of the photonic planar waveguide 100. Thus, the photonic planar waveguide 210 can be programmed to perform a desired function or operation on the input optical signal 201 and / or to obtain a desired output optical signal 203.

[0076] In some implementations, as shown in FIG. 2, the core layer 212 of the photonic planar waveguide 210 can be made of a photoconductive material so that the photonic planar waveguide 210 can be programmed (or controlled) by projecting a patterned illumination 232 of light onto the core layer 212 to locally change the conductivity of the photoconductive material within the core layer 212, thereby causing a local variation in the electric field across the core layer 212. Based on electro-optic modulation, the local variation in the electric field then results in a change (e.g., Δn) in the refractive index and a non-linear susceptibility (e.g., χ (2)) can induce changes in Δn and χ. (2) To achieve large changes in (2) , the photoconductive material can be selected to have low loss, high breakdown electric field, high χ (3) nonlinearity, and / or high photoconductivity. In some examples, the photoconductive material includes silicon-rich silicon nitride (SRN), silicon nitride, silicon carbide, aluminum nitride, amorphous silicon, crystalline silicon, liquid crystal, barium titanate, or lithium niobate.

[0077] In some implementations, as shown in FIG. 2, the patterned illumination 232 can be achieved by a light deflection device 230 that receives illumination 221 from a light source 220 and individually deflects each illumination spot 231 to a plurality of different regions 211a on the upper surface of the photonic planar waveguide 210 (e.g., the upper surface of the upper planar electrode layer 216a). For example, the light deflection device 230 can include a digital micromirror device (DMD) that can have several (e.g., thousands of) microscopic mirrors arranged in a rectangular array on its surface. The mirrors can be individually rotated to an on or off state, for example, within an angular range of ±10° to 12°. In the on state, the illumination spot 231 is deflected (e.g., reflected) to a corresponding region on the upper surface, such as 211a. In the off state, the illumination spot 231 is directed to another location such that the illumination is not in the corresponding region, such as 211b.

[0078] The layers above the core layer 212, such as the upper planar electrode layer 216a and the upper cladding layer 214a, can be made of a transparent or partially transparent material so that the illumination spot 231 can be transmitted to the core layer 212 to change the conductivity of the photoconductive material in the corresponding region within the core layer 212. In some examples, amorphous silicon or silicon-rich silicon nitride (SRN) can be used for the photoconductive material, silicon dioxide can be used for the cladding layers 214a, 214b, and indium tin oxide (ITO) can be used for the planar electrode layer 216a. The planar electrode layer 216b can be made of a metal such as ITO or gold.

[0079] Illumination 221 from the light source 220 can have a wavelength sufficient to change the conductivity of the photoconductive material. The wavelength can be selected based on the photoconductive material. For example, it can be selected based on whether the photoconductive material can absorb light having that wavelength or whether the photon energy of the light having that wavelength is greater than the bandgap of the photoconductive material. The bandgap of the material can be adjusted by synthesizing it with one or more other materials. For example, when the photoconductive material is amorphous silicon, the wavelength sufficient to change the conductivity of amorphous silicon can be, for example, in the range from 200 nm to 700 nm. When the photoconductive material is silicon-rich silicon nitride (SRN), the wavelength sufficient to change the conductivity of SRN can be, for example, in the range from 500 nm to 800 nm. In some examples, the light source 220 includes, for example, a laser, a laser diode, or a light-emitting diode (LED) that provides light in the range from 100 nm to 2000 nm. For example, the light source 220 can be an ultraviolet (UV) LED that generates light having a wavelength in the range from 100 nm to 400 nm, a blue LED that generates light having a wavelength in the range from 400 nm to 500 nm, a green LED that generates light having a wavelength in the range from 500 nm to 565 nm, or a red LED that generates light having a wavelength in the range from 600 nm to 700 nm. As another example, the light source 220 can be a near-infrared laser diode that generates light having a wavelength in the range from 705 nm to 2000 nm.

[0080] It should be noted that the illumination 221 from the light source can have a wavelength different from the wavelength of the input optical signal 201. As described above, the illumination 221 has a wavelength sufficient to change the conductivity of the photoconductive material, and the wavelength of the illumination 221 is determined based on the characteristics of the photoconductive material. In contrast, the wavelength of the input optical signal 201 is determined based on the target signal to be achieved, and the wavelength of the input optical signal 201 can be sufficient to travel within the core layer 212 of the photonic waveguide 210.

[0081] When there is no illumination on the photoconductive material in the region, there is no change or almost no change in the refractive index of the photoconductive material or the photoresist in the region. In contrast, when there is an illumination spot on the photoconductive material in the region, the conductivity of the photoconductive material in the region may become larger, and thus the refractive index of the photoconductive material in the region may become smaller, and the photoresist in the region may become smaller.

[0082] As shown in FIG. 2, the first region corresponding to the region 211b without illumination has a photoresist 213b, and the second region corresponding to the region 211a with illumination has a photoresist 213a that can be much smaller than the photoresist 213b. Therefore, the patterned illumination 232 on different regions of the core layer 212 can cause local variations in the photoresist within different regions of the core layer 212. When a voltage Vs is applied across the photonic planar waveguide 210 to generate an electric field across the core layer 212, the patterned illumination 232 can be directly converted into a spatial electric field distribution across different regions of the core layer 212. By utilizing the Kerr effect and the electric-field-induced second harmonic (EFISH) effect in optics, the programmed electric field across the core layer 212 can induce changes in the refractive index and the nonlinear susceptibility of the core layer 212. By setting or managing the basic optical properties, the photonic planar waveguide 210 can be used to programmatically manipulate light. For example, as shown in FIG. 2, the output optical signal 203 can have a different pulse profile from the input optical signal 201.

[0083] Since the regions within the core layer 212 correspond to different regions 211a, 211b on the upper surface of the photonic planar waveguide 210 defined by the patterned illumination 232, the regions are virtually generated and can be dynamically changed as desired. The resolution of the regions within the core layer 212, for example, the minimum size of the regions, can be determined by the diffraction limit of the illumination 221 from the light source 220, for example, according to the Rayleigh criterion, rather than by manufacturing limitations. The diffraction limit is in the 100s nm.

[0084] The patterned illumination changes the optical conductivity of the optically conductive material and thus changes the optical conductivity of the photoresistor within the region containing the optically conductive material. Since the electric field is applied across the core layer 212, the response time of the photonic planar waveguide 210 can be limited by the time constant of an equivalent RC (resistor-capacitance) circuit, for example, microseconds (μs).

[0085] In some implementations, to shorten the response time of the photonic planar waveguide 210 and increase the operating frequency, the planar electrode layers 216a, 216b can be configured as at least a part of the cladding layers 214a, 214b. For example, the planar electrode layers 216a, 216b can be between the cladding layers 214a, 214b and disposed directly opposite the core layer 212. That is, the core layer 212 can be directly adjacent to the planar electrode layers 216a, 216b. In this way, the response time of the photonic planar waveguide 210 can be shortened to, for example, nanoseconds (ns), and the operating frequency can be increased to GHz. Further, by using the planar electrode layers 216a, 216b to simultaneously function as at least a part of the cladding layers 214a, 214b, the photonic planar waveguide 210 can be miniaturized to a size smaller than the photonic planar waveguide 210 shown in FIG. 2.

[0086] In some implementations, the system 200 includes a controller 260 that can be coupled to at least one of the optical signal source 202, the power supply 240, the light source 220, the optical deflection device 230, or the optical receiver 204. The controller 260 can include one or more processing units (e.g., processors) configured to generate at least one control signal based on at least one target optical signal. The at least one control signal can correspond to at least one of the two-dimensional (2D) refractive index profile and / or the 2D nonlinear susceptibility profile in the core layer. The controller 260 can transmit the at least one control signal to at least one of the optical signal source 202, the light source 220, the optical deflection device 230, or the power supply 240.

[0087] In some examples, at least one control signal includes at least one of a first control signal to a light source 220 to generate a corresponding illumination 221 (e.g., having a desired wavelength and / or intensity), a second control signal to an optical deflection device 230 to control the corresponding illumination 221 to generate a corresponding patterned illumination 232 on the photoconductive material, a third control signal to a power supply 240 to generate a corresponding voltage (e.g., thousands of volts) applied across the photonic planar waveguide 210, or a fourth control signal to an optical signal source 202 to generate a corresponding input optical signal 201 (e.g., having a particular pulse profile).

[0088] In some examples, the controller 260 can receive an output optical signal 203 from the optical receiver 204, e.g., a programmed optical signal from the photonic planar waveguide 210, and adjust the control signal based on a result of comparing the output optical signal 203 with at least one target optical signal used to generate the control signal.

[0089] In some implementations, parameters of the system 200, e.g., the patterned illumination 232, can be determined in software via a physical simulation of the system 200, can be determined in hardware by rapidly iterating between different possible configurations or designs, or can be determined via a combination thereof.

[0090] FIG. 3 is a schematic diagram of another exemplary system 300 that includes an exemplary programmable photonic planar waveguide 210. The system 300 is similar to the system 200 of FIG. 2, except that the system 300 sequentially generates patterned illumination in a plurality of different regions on the top surface of the photonic planar waveguide 210 by an optical scanning system 320, e.g., a raster optical scanning system.

[0091] In system 200, the optical deflection device 230 of FIG. 2 deflects a plurality of illumination spots simultaneously to a plurality of corresponding regions on the upper surface of the photonic planar waveguide 210, for example, by tilting the angles of several mirrors. In contrast, in system 300, the optical scanning system 320 repeatedly scans an illumination spot 321 (e.g., a focused laser spot) across the plane of the upper surface of the photonic planar waveguide 210 to illuminate a selected region 211a in order to generate patterned illumination. The optical scanning system 320 can have a high scanning frequency so that the input optical signal 201 can be continuously manipulated in the core layer 212.

[0092] In some implementations, in addition to the optical deflection device 230 of FIG. 2 or the optical scanning system 320 of FIG. 3, a spatial light modulator (SLM) can be used to generate patterned illumination for different corresponding regions on the upper surface of the photonic planar waveguide. The SLM includes a plurality of elements that can each be modulated by respective control signals, for example, to diffract illumination from the light source 220 of FIG. 2 towards different corresponding regions on the upper surface. The SLM can be a transmissive SLM disposed between the light source and the photonic planar waveguide.

[0093] FIG. 4A is a schematic diagram of an exemplary system 400 including another exemplary programmable photonic planar waveguide 410.

[0094] Unlike the photonic planar waveguide 210 in which the photoconductive material is included in the core layer 212, the photonic planar waveguide 410 can include a non-photoconductive waveguide material (e.g., SiN or silicon) as the material of the core layer 412 between a pair of cladding layers 414a, 414b (e.g., 214a, 214b in FIG. 2 or FIG. 3). Instead, the photonic planar waveguide 410 includes a photoconductive layer 418 disposed outside the core layer 412, e.g., between the upper cladding layer 414a and the upper planar electrode layer 416a (e.g., 216a in FIG. 2 or FIG. 3). In this way, more novel / diverse materials can be independently and separately selected for the core layer 412 and the photoconductive layer 418.

[0095] Similar to the photonic planar waveguide 210, the photonic planar waveguide 410 includes, at both ends, a pair of planar electrode layers including the upper planar electrode layer 416a and the lower planar electrode layer 416b (e.g., 216b in FIG. 2 or FIG. 3). The planar electrode layers 416a, 416b are electrically coupled to a power source 440, e.g., 240 in FIG. 2, and receive a voltage Vs applied across the photonic planar waveguide 410.

[0096] Also, similar to the photonic planar waveguide 210, the photonic planar waveguide 410 is illuminated by a patterned illumination 432 (e.g., 232 in FIG. 2) on the upper surface of the photonic planar waveguide 410 by a light deflection device 430 that receives illumination 421 from, for example, a light source 420 (e.g., 220 in FIG. 2) and deflects a plurality of illumination spots 431 onto the upper surface. Note that other illumination methods discussed above, such as using the optical scanning system 320 of FIG. 3 or using an SLM, can also be applied here to generate the patterned illumination 432.

[0097] As described above, illumination of the photoconductive material can change the conductivity of the photoconductive material and thus change the photoresistor in the region containing the photoconductive material. For example, the photoresistor in the region corresponding to the non-illuminated region 411b can be labeled 413b, and the photoresistor in the region corresponding to the illuminated region 411a can be labeled 413a. As shown in FIG. 4A, the photoresistor 413a can be significantly smaller than the photoresistor 413b due to the change in the conductivity of the photoconductive material by illumination.

[0098] FIG. 4B shows equivalent circuit diagrams 450, 460 of the programmable photonic planar waveguide 410 of FIG. 4A in the illumination-off scenario (i) and the illumination-on scenario (ii). In the equivalent circuit diagram 450, a photoresistor 413b formed in the photoconductive layer 418 and a corresponding resistor 415b formed in a waveguide structure including the core layer 412 and the cladding layers 414a, 414b are coupled in series to the voltage Vs. In the equivalent circuit diagram 460, a photoresistor 413a formed in the photoconductive layer 418 and a corresponding resistor 415a formed in a waveguide structure including the core layer 412 and the cladding layers 414a, 414b are coupled in series to the voltage Vs. The resistor 415a can be the same as the resistor 415b.

[0099] In equivalent circuit diagram 450, without illumination of the photoconductive material, photoresistor 413b may be significantly larger than resistor 415b. Thus, the first divided voltage across photoresistor 413b may be close to Vs, and the second divided voltage across resistor 415b may be close to 0. Thus, there is no change in the refractive index, e.g., Δn = 0. In contrast, in equivalent circuit diagram 460, upon illumination of the photoconductive material, photoresistor 413b can be changed to photoresistor 413a, which may be significantly smaller than resistor 415a. Thus, the first divided voltage across photoresistor 413a can be reduced to approximately 0, and the second divided voltage across resistor 415a can be increased to approximately Vs. Thus, due to the DC Kerr effect and the EFISH effect, there may be a change in the refractive index and / or the nonlinear susceptibility, e.g., Δn ≠ 0, and / or χ (2) ≠ 0.

[0100] Thus, when patterned illumination 432 is on photoconductive layer 418 and voltage Vs is applied across photonic planar waveguide 410, 2D refractive index or nonlinear susceptibility variations in core layer 412 can be obtained, and thus, input optical signal 401 (e.g., 201 of FIG. 2 or FIG. 3) coupled to core layer 412 can be manipulated to be output optical signal 403 (e.g., 203 of FIG. 2 or FIG. 3).

[0101] FIG. 5 is a schematic diagram of another system 500 that includes another exemplary programmable photonic planar waveguide 510.

[0102] Similar to the photonic planar waveguides 210 or 410, the photonic planar waveguide 510 includes a core layer 512 between a pair of cladding layers 514a, 514b. The photonic planar waveguide 510 can also include an upper planar electrode layer 516 and a lower planar electrode layer 518 on the upper cladding layer 514a and the lower cladding layer 514b, respectively. In some cases, the core layer 512 can be the core layer 212 of FIG. 2 or FIG. 3 that includes a photoconductive material. In another case, the core layer 512 can be the core layer 412 of FIG. 4A that includes a non-photoconductive material, and a separate photoconductive layer, such as the photoconductive layer 418 of FIG. 4A, can be within the photonic planar waveguide 510, for example, between the upper planar electrode layer 516 and the upper cladding layer 514a.

[0103] However, unlike the upper planar electrode layer 216a of FIG. 2 or FIG. 3, or the planar layer 416a of FIG. 4A, the upper planar electrode layer 516 includes an array of pixelated electrodes 517. The array of pixelated electrodes 517 can be physically fabricated (e.g., by photolithography) and can also define the resolution of the programmable photonic planar waveguide 510. Each pixelated electrode 517 within the pixelated electrode layer 516 can be configured to receive respective voltages V(x,z), e.g., V 00 , V 10 , V 20 ,..., V 0m , V 1m , V 2m ,..., V 0n , V 1n , V 2n can be configured to receive. The lower planar electrode layer 518 can be commonly coupled to ground. Each voltage 520 to the pixelated electrodes 517 causes a corresponding local variation in at least one of the refractive index or the non-linear susceptibility of the core layer 512, resulting in respective local electric fields E DC(x,z) can be controlled to vary, which is different from using the patterned illumination described in FIGS. 2, 3, or 4A. Thus, the input optical signal 501 (e.g., 201 in FIG. 2 or FIG. 3) coupled to the core layer 412 can be operated to become the output optical signal 503 (e.g., 203 in FIG. 2 or FIG. 3).

[0104] As shown in FIGS. 1 to 5, the above implementation is discussed with respect to a 2D photonic planar waveguide. The techniques implemented in the present disclosure can also be applied to 1D photonic waveguides.

[0105] In some implementations, a programmable photonic waveguide includes a 1D waveguide structure extending along a longitudinal direction and first and second planar electrode layers extending parallel to each other along the longitudinal direction. The 1D waveguide structure is between the first and second planar electrode layers. The 1D waveguide structure can include a waveguide core and a cladding layer surrounding the waveguide core. The 1D waveguide structure can also be made of a photoconductive material and include a photoconductive layer extending along the longitudinal direction. The photoconductive layer can be included within the waveguide core or as part of the cladding layer, for example, between the cladding layer and one of the first and second planar electrode layers.

[0106] In the operation of the programmable photonic waveguide, a voltage is applied across the waveguide structure via the planar electrode layers, and while the voltage is applied across the waveguide structure, patterned illumination of light is projected onto a plurality of different corresponding regions of the photoconductive layer along the longitudinal direction to locally change the conductivity of the photoconductive material in the photoconductive layer so as to cause a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the waveguide core along the longitudinal direction. The optical signal can be coupled to the waveguide core and propagate through the waveguide core with a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility along the longitudinal direction.

[0107] In a programmable photonic waveguide, light is restricted to move in 1D, which can have significant advantages such as achieving stronger nonlinear interactions or obtaining specific desired optical spectral responses.

[0108] The techniques implemented in this disclosure can also be applied to 3D photonic devices including photoconductive materials. For example, using two or more optical beams to illuminate selected regions within a photoconductive material can generate a 3D refractive index or nonlinear susceptibility profile, thereby enabling manipulation of light within the 3D photonic device.

[0109] Exemplary process FIG. 6A is a flowchart of an exemplary process 600 for managing a programmable photonic waveguide. The programmable photonic waveguide can be the programmable photonic waveguide 100 of FIG. 1, 210 of FIG. 2 or FIG. 3, 410 of FIG. 4A, or 510 of FIG. 5. Process 600 can be executed by a system including a programmable photonic waveguide, such as system 200 of FIG. 2, system 300 of FIG. 3, system 400 of FIG. 4A, or system 500 of FIG. 5. The system can include a controller configured to control the operation of the programmable photonic waveguide, such as controller 260 of FIG. 2.

[0110] At 602, each local electric field across a plurality of regions of the waveguide core of the waveguide structure within the programmable photonic waveguide is varied to cause a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the waveguide core. The waveguide core can be between pairs of cladding layers within the waveguide structure such that light can be confined within and travel through the waveguide core.

[0111] At 604, an optical signal is programmed by coupling the optical signal passing through the waveguide core with the local variations in at least one of the refractive index or the nonlinear susceptibility of the waveguide core.

[0112] In some implementations, the photonic waveguide can have a structure similar to the photonic waveguide 510 of FIG. 5. In the photonic waveguide, the waveguide structure is between first and second planar electrode layers (e.g., 516, 518 of FIG. 5). The first planar electrode layer (e.g., 516) can include pixelated electrodes (e.g., 517 of FIG. 5) configured to receive respective voltages (e.g., 520 of FIG. 5). The second planar electrode layer can be commonly coupled to ground. During operation, each local electric field across a plurality of regions of the waveguide core (e.g., core layer 512 of FIG. 5) can be varied by changing the respective voltages coupled to the plurality of pixelated electrodes to vary each local electric field across the plurality of regions of the waveguide core. The plurality of pixelated electrodes correspond to the plurality of regions of the waveguide core.

[0113] In some implementations, the photonic waveguide can have a structure similar to the photonic waveguide 210 of FIG. 2 or FIG. 3, or 410 of FIG. 4A. The photonic waveguide includes a photoconductive material responsive to optical illumination, and this photoconductive material can be used to generate a local electric field within the waveguide core, e.g., core layer 212 of FIG. 2 or FIG. 3, or core layer 412 of FIG. 4A, as further discussed in FIG. 6B.

[0114] FIG. 6B is a flowchart of an exemplary process 610 for generating a local electric field within a waveguide core. Process 610 can be implemented as step 602 of FIG. 6A.

[0115] At 612, light illuminates the photonic waveguide to generate a patterned illumination of light on the photoconductive material to locally vary the conductivity of the photoconductive material.

[0116] In some implementations, as shown in FIG. 2, light can be illuminated on the photonic waveguide by, for example, individually deflecting each illumination spot of the light to a plurality of different corresponding regions on the upper surface of the photonic waveguide by the light deflection device 230 of FIG. 2 to generate a patterned illumination of the light.

[0117] In some implementations, as shown in FIG. 3, light can be illuminated on the photonic waveguide by, for example, sequentially scanning the illumination spots of the light over a plurality of different corresponding regions on the upper surface of the photonic waveguide by the light scanning system 320 of FIG. 3 to generate a patterned illumination.

[0118] In some implementations, light can be illuminated on the photonic waveguide by modulating a plurality of elements of a spatial light modulator (SLM) to diffract the light in order to generate a patterned illumination in a plurality of different corresponding regions on the upper surface of the photonic waveguide.

[0119] At 614, while illuminating the photonic waveguide with light, a voltage is applied across the waveguide structure to cause respective local electric field variations across a plurality of regions of the waveguide core. The patterned illumination of the light on the photoconductive material corresponds to a plurality of regions of the waveguide core.

[0120] Returning to FIG. 6A, process 600 can further include generating a control signal based on at least one target optical signal. The at least one control signal can correspond to at least one of a two-dimensional (2D) refractive index profile or a 2D nonlinear susceptibility profile in the waveguide core.

[0121] In some implementations, the control signal is used to control at least one of the illumination of the light on the photonic waveguide, the voltage applied across the waveguide structure, or the optical signal coupled through the waveguide core.

[0122] In some implementations, process 600 can further include receiving a programmed optical signal coupled from a waveguide core and adjusting a control signal based on a result of comparing the programmed optical signal with at least one target optical signal.

[0123] In some implementations, the waveguide core includes, for example, an optically conductive material as shown in FIG. 2 or FIG. 3. In some implementations, the optically conductive material is included within an optically conductive layer (e.g., 418 in FIG. 4A) disposed between an upper planar electrode layer (e.g., 416a in FIG. 4A) and an upper cladding layer (e.g., 414a in FIG. 4A). Light is illuminated onto the optically conductive layer through the upper planar electrode layer.

[0124] In some examples, the optically conductive material includes at least one of silicon-rich silicon nitride (SRN), silicon nitride, silicon carbide, amorphous silicon, crystalline silicon, liquid crystal, barium titanate, or lithium niobate.

[0125] In some examples, the corresponding local variation in the refractive index of the waveguide core is in the range from 10 -4 to greater than 0.1. The corresponding local variation in the second-order nonlinear susceptibility of the waveguide core can be in the range from 1 pm / V to greater than 10 3 pm / V.

[0126] Exemplary Applications The programmable photonic devices implemented in the present disclosure, by their nature, can change their functionality and thus can be applied in various settings. To implement several different functions, several programmable photonic devices can be integrated within a chip.

[0127] In some examples, a programmable photonic waveguide is used to instantiate a generally tunable optical component that is useful in a more general photonic context, e.g., for optical sensing or long-distance communication applications. The optical component can include instantiating a complex optical filter, an optical demultiplexer / combiner, a reconfigurable optical add-drop multiplexer, and / or a complex optical cavity or device.

[0128] In some examples, a programmable photonic waveguide can be used to perform machine learning classification, e.g., by inputting machine learning data into an input port of the waveguide, and after undergoing some complex wave dynamics within an integrated photonic chip that includes the waveguide, an output prediction class can be read out from an output port of the waveguide. Similar techniques can also be used to solve other difficult computational problems that are industrially or scientifically relevant, e.g., combinatorial optimization problems or partial differential equations. In some examples, the programmable complex wave dynamics within the waveguide can be utilized to perform calculations of complex mathematical functions, e.g., fully programmable matrix multiplications.

[0129] The disclosed examples and other examples can be implemented as one or more modules of computer program instructions encoded on a computer-readable medium for execution by, for example, one or more computer program products, a data processing apparatus, or to control the operation of a data processing apparatus. The computer-readable medium can be a machine-readable storage medium, a machine-readable storage substrate, a memory device, or a combination of one or more of them. The term "data processing apparatus" includes, by way of example, all apparatus, devices, and machines for processing data, including programmable processors, computers, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, for example, code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.

[0130] The system can include, by way of example, all apparatus, devices, and machines for processing data, including programmable processors, computers, or multiple processors or computers. The system can include, in addition to hardware, code that creates an execution environment for the computer program in question, for example, code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.

[0131] A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. The program can be stored in part of a file that holds other programs or data (such as one or more scripts stored within a markup language document), in a single file dedicated to the program in question, or in multiple related files (such as files that store one or more modules, subprograms, or portions of code). A computer program can be deployed to execute on one computer or be located at one site, or be distributed across multiple sites and executed on multiple computers interconnected by a communication network.

[0132] The processes and logical flows described in this document can be executed by one or more programmable processors executing one or more computer programs to perform the functions described in this document. The processes and logical flows can also be executed by, and the apparatus can also be implemented as, special purpose logic circuitry, such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0133] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, as well as any one or more processors of any kind of digital computer. In general, a processor receives instructions and data from a read only memory or a random access memory or both. Essential elements of a computer can include a processor for executing instructions and one or more memory devices for storing the instructions and data. In general, a computer can also include one or more mass storage devices for storing data, such as, magnetic disks, magneto-optical disks, or optical disks, or can be operatively coupled to receive data from, or transmit data to, or both, such mass storage devices. However, a computer need not have such devices. Computer-readable media suitable for storing computer program instructions and data can include, by way of example, all forms of non-volatile memory, media, and memory devices including EPROM, EEPROM, and flash memory devices, magnetic disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[0134] Although this document may describe many details, these should not be construed as limitations on the scope of the claimed invention or what may be claimed, but rather as descriptions of features specific to particular embodiments. Specific features described in this document in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any suitable sub-combination. Further, even if a feature is described above as acting in a particular combination and may even initially be claimed as such, one or more features from the claimed combination may, in some cases, be excluded from that combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination. Similarly, although operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order or sequentially shown, or that all illustrated operations be performed, in order to achieve the desired result.

[0135] Some implementations have been described. However, it will be understood that various changes may be made without departing from the spirit and scope of the techniques and devices described herein. For example, the phase perturbation or variation methods discussed above may be implemented in a diffraction structure to remove high-frequency or mid-frequency artifacts in an interference pattern. The features shown in each of the implementations may be used independently or in combination with each other. Additional features and variations may also be included in the implementations. Accordingly, other implementations are within the scope of the following claims.

Description of Reference Numerals

[0136] 100 Photonic waveguide 101 Input optical signal 102 First end 103 Output optical signal 104 Second opposite end 106 Region 200 System 201 Input optical signal 202 Optical signal source 203 Output optical signal 204 Optical receiver 210 Programmable photonic planar waveguide, photonic planar waveguide, photonic waveguide 211a Region 211b Region 212 Core layer 213a Photoresist 213b Photoresist 214a Cladding layer, upper cladding layer 214b Cladding layer, lower cladding layer 216a Upper planar electrode layer, planar electrode layer 216b Lower planar electrode layer, planar electrode layer 220 Light source 221 Illumination 230 Optical deflection device 231 Illumination spot 232 Patterned illumination of light, patterned illumination 240 Power supply 260 Controller 300 System 320 Optical scanning system 321 Illumination spot 400 System 401 Input optical signal 403 Output optical signal 410 Programmable photonic planar waveguide, photonic planar waveguide 411a Region 411b Region 412 Core layer 413a Photoresist 413b Photoresist 414a Cladding layer, upper cladding layer 414b Cladding layer 415a Resistor 415b Resistor 416a Upper planar electrode layer, planar electrode layer 416b Lower planar electrode layer, planar electrode layer 418 Photoconductive layer 420 Light source 421 Lighting 430 Optical deflection device 431 Lighting spot 432 Patterned lighting 440 Power supply 450 Equivalent circuit diagram 460 Equivalent circuit diagram 500 System 501 Input optical signal 503 Output optical signal 510 Programmable photonic planar waveguide, photonic planar waveguide, photonic waveguide 512 Core layer 514a Cladding layer, upper cladding layer 514b Cladding layer, lower cladding layer 516 Upper planar electrode layer, pixelated electrode layer 517 Pixelated electrode 518 Lower planar electrode layer 520 Voltage

Claims

1. A programmable device extending in a plane, wherein the programmable device comprises: a pair of planar electrode layers extending parallel to each other, a waveguide structure comprising a core layer and a pair of cladding layers on opposite sides of the core layer, wherein the core layer is between the planar electrode layers and the waveguide structure comprises an optically conductive material, a programmable device; a power supply electrically connected to the planar electrode layer and configured to apply a voltage across the waveguide structure during operation of the programmable system; a light source configured to generate illumination at a wavelength sufficient to change the conductivity of the optically conductive material; a spatial light controller arranged to receive the illumination from the light source and illuminate the optically conductive material with patterned illumination sufficient to locally change the conductivity of the optically conductive material while the voltage is applied across the waveguide structure; an optical signal source arranged to direct an optical signal towards an end of the waveguide structure to couple the optical signal into the core layer while the optically conductive material is illuminated with the patterned illumination and the voltage is applied across the waveguide structure A programmable system comprising.

2. The programmable system according to claim 1, wherein the patterned illumination is configured to locally change the conductivity of the optically conductive material sufficient to cause a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the core layer during operation of the programmable system.

3. The programmable system according to claim 2, wherein the patterned illumination to the optically conductive material and the voltage applied across the waveguide structure generate a local variation in the electric field across a plurality of regions of the core layer such that a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the core layer is caused.

4. The corresponding local variation of the refractive index of the core layer is in the range from 10 －４ to greater than 0.1, the programmable system according to claim 2 or 3.

5. The corresponding local variation of the second-order nonlinear susceptibility of the core layer is in the range from 1 pm / V to beyond 10 ３ programmable system according to any one of claims 2 to 4, wherein the pm / V.

6. The programmable system according to any one of claims 1 to 5, wherein the core layer comprises the optically conductive material.

7. The programmable system according to claim 6, wherein at least one of the planar electrode layers is configured as at least a part of the cladding layer.

8. The programmable system according to claim 6, wherein the core layer is directly adjacent to the pair of planar electrode layers between the pair of clad layers.

9. The programmable system according to any one of claims 1 to 5, wherein the light conductive material is arranged in a layer different from the core layer.

10. The programmable system according to claim 9, wherein the layer containing the light conductive material is above the core layer and between the upper planar electrode layer of the planar electrode layers and the upper clad layer of the clad layers.

11. The programmable system according to any one of claims 1 to 10, wherein the spatial light controller includes an optical deflection device configured to individually deflect respective illumination spots of the illumination to a plurality of different corresponding regions on the upper surface of the programmable device to generate the patterned illumination.

12. The programmable system according to claim 11, wherein the optical polarization device comprises a digital micromirror device (DMD).

13. The programmable system according to any one of claims 1 to 10, wherein the spatial light controller includes an optical scanner configured to sequentially scan illumination spots of the illumination from the light source over a plurality of different corresponding regions on the upper surface of the programmable device to generate the patterned illumination.

14. The programmable system according to claim 13, wherein the optical scanner comprises a raster optical scanning device.

15. The programmable system according to any one of claims 1 to 10, wherein the spatial light controller comprises a spatial light modulator (SLM) having a plurality of elements configured to be modulated to diffract the illumination from the light source to generate the patterned illumination in a plurality of different corresponding regions on the upper surface of the programmable device.

16. The programmable system according to claim 15, wherein the spatial light controller comprises a transmissive SLM between the light source and the programmable device.

17. The programmable system according to any one of claims 1 to 16, further comprising a controller coupled to at least one of the power supply, the light source, the spatial light controller, or the optical signal source.

18. the controller to generate at least one control signal based on at least one target optical signal, wherein the at least one control signal corresponds to at least one of a two-dimensional (2D) refractive index profile or a 2D nonlinear susceptibility profile in the core layer; and transmit the at least one control signal to at least one of the power supply, the light source, the spatial light controller, or the optical signal source A programmable system according to claim 17, configured to perform the above. **Claim 19** wherein the at least one control signal includes a first control signal to the light source for generating corresponding illumination; a second control signal to the spatial light controller for controlling the corresponding illumination to generate corresponding patterned illumination on the photoconductive material; a third control signal to the power supply for generating a corresponding voltage applied across the waveguide structure; or a fourth control signal to the optical signal source for generating a corresponding input optical signal A programmable system according to claim 18, comprising at least one of the above. **Claim 20** A programmable system according to any one of claims 1 to 19, further comprising an optical receiver configured to receive an output optical signal coupled from the waveguide structure. **Claim 21** wherein the photoconductive material includes at least one of silicon-rich silicon nitride (SRN), silicon nitride, amorphous silicon, crystalline silicon, liquid crystal, barium titanate, silicon carbide, aluminum nitride, or lithium niobate. A programmable system according to any one of claims 1 to 20. **Claim 22** A programmable device, extending in a plane, comprising a core layer, a pair of cladding layers on opposite sides of the core layer, and a waveguide structure having the pair of cladding layers; a pair of planar electrode layers extending parallel to each other, with the core layer between the planar electrode layers; and a photoconductive layer including a photoconductive material wherein, in operation of the programmable device, a voltage is applied across the waveguide structure via the planar electrode layers. ​ While the voltage is being applied across the waveguide structure, patterned illumination of light is projected onto individual regions of the photoconductive layer to locally vary the conductivity of the photoconductive material within the photoconductive layer so as to cause a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the core layer. A programmable device in which an optical signal is coupled to the core layer and propagates through the core layer with the corresponding local variation in at least one of the refractive index or the nonlinear susceptibility. **Claim 23** The programmable device according to claim 22, wherein the core layer includes the photoconductive layer. **Claim 24** The programmable device according to claim 23, wherein at least one of the planar electrode layers is configured as at least a part of the cladding layer. **Claim 25** The programmable device according to claim 24, wherein the core layer is directly adjacent to a pair of the planar electrode layers that are between a pair of the cladding layers. **Claim 26** The programmable device according to claim 22, wherein the photoconductive layer is different from the core layer. **Claim 27** The programmable device according to claim 26, wherein the photoconductive layer is above the core layer and is between an upper planar electrode layer of the planar electrode layers and an upper cladding layer of the cladding layers. **Claim 28** The patterned illumination to the photoconductive layer and the voltage applied across the waveguide structure generate a local variation in the electric field across a plurality of different corresponding regions of the core layer so as to cause the corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the core layer. The programmable device according to any one of claims 22 to 27. **Claim 29** The photoconductive material includes at least one of silicon-rich silicon nitride (SRN), silicon nitride, amorphous silicon, crystalline silicon, liquid crystal, barium titanate, silicon carbide, aluminum nitride, or lithium niobate. The programmable device according to any one of claims 22 to 28. **Claim 30** A programmable device, which is a waveguide structure, having a core layer, and a pair of cladding layers on opposite sides of the core layer and is a waveguide structure. First and second planar electrode layers extending parallel to each other, wherein the waveguide structure is between the first planar electrode layer and the second planar electrode layer, the first and second planar electrode layers comprising The first planar electrode layer comprises a plurality of pixelated electrodes insulated from each other, each of the pixelated electrodes being individually controlled to receive a respective voltage, and the second planar electrode layer being commonly coupled to ground, In the operation of the programmable device, Individual voltages are applied to the plurality of pixelated electrodes to generate a locally varying electric field across the core layer so as to cause a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the core layer, A programmable device in which an optical signal is coupled to the core layer and propagates through the core layer with the corresponding local variation in at least one of the refractive index or the nonlinear susceptibility.

31. A programmable device, extending along a longitudinal direction, a waveguide core, a cladding layer surrounding the waveguide core and having a one-dimensional waveguide structure, a photoconductive layer including a photoconductive material and extending along the longitudinal direction, First and second planar electrode layers extending parallel to each other along the longitudinal direction, wherein the waveguide structure is between the first planar electrode layer and the second planar electrode layer, the first and second planar electrode layers comprising In the operation of the programmable device, A voltage is applied across the waveguide structure via the planar electrode layer, While the voltage is applied across the waveguide structure, patterned illumination of light is projected onto a plurality of different corresponding regions of the photoconductive layer along the longitudinal direction to locally vary the conductivity of the photoconductive material in the photoconductive layer so as to cause a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the waveguide core along the longitudinal direction, A programmable device in which an optical signal is coupled to the waveguide core and propagates through the waveguide core with the corresponding local variation in at least one of the refractive index or the nonlinear susceptibility along the longitudinal direction.

32. A method of managing a programmable device, Illuminating the programmable device with light to generate a patterned illumination of light on the photoconductive layer of the programmable device so as to locally vary the conductivity of the photoconductive material in the photoconductive layer, the programmable device including a waveguide structure extending in a plane and having a core layer and a pair of cladding layers on opposite sides of the core layer, the step of: Applying a voltage across the waveguide structure through a pair of planar electrode layers of the programmable device so as to cause a corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the core layer while illuminating the programmable device with the light; Programming the optical signal by coupling the optical signal passing through the core layer with the corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the core layer; A method comprising.

33. The method according to claim 32, wherein the core layer includes a photoconductive layer.

34. The method according to claim 32, wherein the photoconductive layer is disposed between an upper planar electrode layer of the planar electrode layers and an upper cladding layer of the cladding layers, and the light is illuminated on the photoconductive layer through the upper planar electrode layer.

35. The step of illuminating the programmable device with the light is The method according to any one of claims 32 to 34, including the step of individually deflecting respective illumination spots of the light to a plurality of different corresponding regions on the upper surface of the programmable device to generate the patterned illumination of the light.

36. The step of illuminating the programmable device with the light is The method according to any one of claims 32 to 34, including the step of sequentially scanning the illumination spots of the light across a plurality of different corresponding regions on the upper surface of the programmable device to generate the patterned illumination.

37. The step of illuminating the programmable device with the light is The method according to any one of claims 32 to 34, including the step of modulating a plurality of elements of a spatial light modulator (SLM) to diffract the light to generate the patterned illumination in a plurality of different corresponding regions on the upper surface of the programmable device.

38. Generating at least one control signal based on at least one target optical signal, wherein the at least one control signal corresponds to at least one of a two-dimensional (2D) refractive index profile or a 2D nonlinear susceptibility profile in the core layer; Using the control signal, Illuminating the light on the programmable device, Applying the voltage across the waveguide structure, or The optical signal coupled through the core layer Using the control signal to control at least one of them; The method according to any one of claims 32 to 37, further comprising.

39. Receiving the programmed optical signal coupled from the core layer; Adjusting the control signal based on a result of comparing the programmed optical signal with the at least one target optical signal; The method according to claim 38, further comprising.

40. A method of managing a programmable device, comprising: Varying respective local electric fields across a plurality of regions of the waveguide core of the waveguide structure within the programmable device to cause corresponding local variations in at least one of the refractive index or the nonlinear susceptibility of the waveguide core; Programming the optical signal by coupling the optical signal passing through the waveguide core with the corresponding local variation in at least one of the refractive index or the nonlinear susceptibility of the waveguide core; A method comprising.

41. The step of varying the respective local electric fields across the plurality of regions of the waveguide core comprises: Illuminating the light on the waveguide structure of the programmable device to generate a patterned illumination of light on the photoconductive material within the waveguide structure so as to locally vary the conductivity of the photoconductive material; Applying a voltage across the waveguide structure to cause a change in the respective local electric fields across the plurality of regions of the waveguide core while illuminating the light on the waveguide structure, wherein the patterned illumination of the light on the photoconductive material corresponds to the plurality of regions of the waveguide core; The method according to claim 40, comprising.

42. The waveguide structure is between a first planar electrode layer and a second planar electrode layer, the first planar electrode layer comprising a plurality of pixelated electrodes configured to receive respective voltages, and the second planar electrode layer being commonly coupled to ground, the step of varying the respective local electric fields across the plurality of regions of the waveguide core, the method of claim 40, comprising the step of varying the respective voltages coupled to the plurality of pixelated electrodes to vary the respective local electric fields across the plurality of regions of the waveguide core, wherein the plurality of pixelated electrodes correspond to the plurality of regions of the waveguide core. **Claim 43** The waveguide structure is a one-dimensional (1D) waveguide extending along a longitudinal direction, or a two-dimensional (2D) waveguide extending in a plane and comprising one of the foregoing, the method of claim 40. **Claim 44** A method of manufacturing a programmable system according to any one of claims 1 to 21. **Claim 45** A method of manufacturing a programmable device according to any one of claims 1 to 31.

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