Waveguide having a periodic refractive index clad

Abstract

Various embodiments provide a waveguide with reduced optical power loss. The waveguide includes a waveguide core having a core refractive index and a cladding disposed around at least a portion of the periphery of the waveguide core. The cladding includes a plurality of layers defining a periodic refractive index. The plurality of layers includes a core adjacent layer having a core adjacent layer refractive index. The core refractive index is greater than the core adjacent layer refractive index.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Patent Application No. 18 / 193,994, filed Mar. 31, 2023, which claims priority to U.S. Patent Application No. 63 / 364,812, filed May 17, 2022, the entire contents of which are incorporated herein by reference.

[0002] Various embodiments relate to waveguides with reduced optical loss (compared to conventional waveguides). For example, various embodiments relate to waveguides having a Bragg grating cladding.

Background Art

[0003] Waveguides are used to direct optical signals from a light source (e.g., a laser) to a target location. However, the ability of a waveguide to provide an optical signal can be reduced due to optical power loss as the optical signal propagates through the waveguide. Through the efforts, ingenuity, and new ideas made, many of the deficiencies of such waveguides have been solved by developing solutions constructed in accordance with the embodiments of the present invention. Many of those examples are described in detail herein.

Summary of the Invention

Means for Solving the Problems

[0004] Exemplary embodiments provide a waveguide having a periodic refractive index cladding, where the refractive index of the waveguide core is greater than the refractive index of the core - adjacent layer of the periodic refractive index cladding. Exemplary embodiments provide a waveguide having a cladding formed from alternating layers of a material having a refractive index lower than that of the waveguide core. Various embodiments provide a waveguide having a distributed Bragg grating cladding around at least a portion of the waveguide core. Various embodiments provide a method for manufacturing such waveguides.

[0005] According to one aspect of the present disclosure, an optical waveguide with reduced optical power loss characteristics is provided. In an exemplary embodiment, the optical waveguide includes an optical waveguide core having a core refractive index and a cladding disposed around at least a part of the periphery of the optical waveguide core. The cladding includes a plurality of layers defining a periodic refractive index. The plurality of layers includes a core adjacent layer having a core adjacent layer refractive index. The core refractive index is greater than the core adjacent layer refractive index.

[0006] In an exemplary embodiment, the cladding defines a blocking zone in which the probability of light at a target wavelength or within a target wavelength range scattering into the cladding is reduced therein.

[0007] In an exemplary embodiment, the cladding has a thickness of 2 microns or less.

[0008] In an exemplary embodiment, the plurality of layers includes a plurality of sets of layers, each set of layers including at least a first cladding layer and a second cladding layer, the first cladding layer having a first layer refractive index, the second cladding layer having a second layer refractive index, and the core refractive index being greater than at least one of the first layer refractive index or the second layer refractive index.

[0009] In an exemplary embodiment, the depth of each second cladding layer is in the range between 25 nm and 120 nm, and the depth of each first cladding layer is in the range between 25 nm and 120 nm.

[0010] In an exemplary embodiment, the plurality of sets of layers includes 3 to 15 sets of layers, each set of layers including at least one first cladding layer and one second cladding layer.

[0011] In an exemplary embodiment, the first layer refractive index and the second layer refractive index are different from each other.

[0012] In an exemplary embodiment, the first cladding layer of the first set of layers is disposed immediately adjacent to the optical waveguide core, and the second layer refractive index is greater than the first layer refractive index.

[0013] In an exemplary embodiment, at least one of the first cladding layer or the second cladding layer includes at least one of SiO2, TEOS SiO2, vacuum, air, Al2O3, Si3N4, Si, TiO2, or HfO2.

[0014] In an exemplary embodiment, the cladding is a distributed Bragg grating cladding.

[0015] In an exemplary embodiment, the waveguide core includes one or more of Al2O3, Si3N4, Si, TiO2, or HfO2.

[0016] In an exemplary embodiment, the waveguide core is formed on a substrate.

[0017] According to another aspect of the present disclosure, a method for manufacturing a waveguide is provided. In an exemplary embodiment, the method includes forming a waveguide core, the waveguide core having a core refractive index, and forming a cladding around at least a portion of the waveguide core. The cladding includes a plurality of layers that define a periodic refractive index. The plurality of layers includes a core adjacent layer having a core adjacent layer refractive index. The core refractive index is greater than the core adjacent layer refractive index.

[0018] In an exemplary embodiment, the method further includes performing a smoothing operation on one or more surfaces of the waveguide core before forming the cladding.

[0019] In an exemplary embodiment, forming the waveguide core includes depositing a waveguide core material on a substrate using at least one of atomic layer deposition, chemical vapor deposition, or dielectric sputtering or evaporation.

[0020] In an exemplary embodiment, the step of forming the waveguide core further includes patterning the waveguide core from the waveguide core material using one of (a) photolithography or electron beam (e-beam) lithography followed by dielectric etching, or (b) photoresist followed by plasma-enhanced chemical vapor deposition or evaporation of a waveguide layer formed from the waveguide core material followed by lift-off.

[0021] In an exemplary embodiment, the method further includes performing a photoresist reflow process prior to dielectric etching or lift-off to reduce the roughness of the sidewalls of the waveguide core.

[0022] In an exemplary embodiment, the step of forming the cladding includes sequentially depositing at least a first cladding layer and a second cladding layer around at least a portion of the waveguide core to form a plurality of sets of cladding layers around at least a portion of the waveguide core.

[0023] In an exemplary embodiment, the first cladding layer and the second cladding layer are sequentially formed using at least one of atomic layer deposition or chemical vapor deposition.

[0024] In an exemplary embodiment, the first cladding layer and the second cladding layer are formed by conformal deposition.

[0025] In an exemplary embodiment, the first cladding layer is characterized by a first layer refractive index, the second cladding layer is characterized by a second layer refractive index, and the first layer refractive index and the second layer refractive index are different from each other.

[0026] In an exemplary embodiment, the method further includes performing chemical mechanical polishing of the outer surface of the cladding.

[0027] Although the invention has been described in general terms, reference is now made to the accompanying drawings, which are not necessarily drawn to scale.

Brief Description of the Drawings

[0028]

Figure 1

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[0029] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. The term "or" (also denoted " / ") is used herein in both an alternative and a conjunctive sense, unless otherwise specified. The terms "illustrative" and "exemplary" are used to provide examples that do not indicate any level of quality. The terms "generally", "substantially", and "approximately" mean within engineering and / or manufacturing limits and / or within the measurement capabilities of the user, unless otherwise specified. Throughout, like numbers refer to like elements.

[0030] In various scenarios, an optical signal is provided through a waveguide. The roughness of the surface of the waveguide can cause scattering events, resulting in a loss of optical power from the waveguide as the optical signal travels through the waveguide. Various embodiments provide waveguides with reduced optical power loss and methods of manufacturing such waveguides. In various embodiments, the optical power loss of the waveguide is reduced through the use of a cladding around at least a portion of the waveguide having a modulated and / or periodic refractive index. In various embodiments, the modulated and / or periodic refractive index of the cladding defines a blocking zone in which the transmission of scattered light from the optical signal, due to the optical signal propagating through a waveguide core that interacts with the rough walls of the waveguide core, is prevented and / or minimized. Thus, the overall optical power loss of the optical signal propagating along the waveguide is reduced.

[0031] Exemplary waveguide having a periodic refractive index cladding FIG. 1 illustrates a cross-sectional view of an exemplary waveguide 100 according to an exemplary embodiment. The cross-sectional view of the waveguide 100 is taken in a plane substantially perpendicular to the guided propagation direction β of the waveguide 100. In various embodiments, the waveguide 100 includes a waveguide core 110 and a cladding 120 disposed at least partially around the waveguide core 110. In an exemplary embodiment, the waveguide core 110 and the cladding 120 are formed on a substrate 105.

[0032] In various embodiments, the waveguide core 110 is made of and / or includes a material having a core refractive index. For example, in various embodiments, the waveguide core 110 includes one or more of Al2O3, Si3N4, Si (e.g., amorphous Si, polysilicon, etc.), TiO2, or HfO2.

[0033] In various embodiments, the cladding 120 is characterized at least in part by a modulated or periodic refractive index. For example, the refractive index of the cladding 120 is not constant throughout the cladding. Rather, the refractive index of the cladding 120 is modulated and / or periodic along a path having a consistent direction pointing outward from the surface of the waveguide core 110 toward the surrounding environment. As used herein, a periodic refractive index means that as a path proceeds outward from the surface of the waveguide core 110 (e.g., from the sidewall 115) through the cladding 120 to the surrounding environment, the refractive index of the cladding 120 is not constant in a periodic and / or repeating manner. For example, in various embodiments, the refractive index is a step function that alternates sequentially through a set of values. The refractive index of the portion of the cladding that interfaces with and / or is directly / immediately adjacent to the waveguide core is less than the core refractive index.

[0034] In various embodiments, the cladding 120 comprises a plurality of layers. The innermost layer (e.g., the layer that interfaces with and / or is directly adjacent to the waveguide core 110) is herein referred to as the core adjacent layer 126. The refractive index of the core adjacent layer 126 is herein referred to as the core adjacent layer refractive index. In various embodiments, the core adjacent layer refractive index is less than the core refractive index. In various embodiments, the refractive index of each of the remaining layers of the plurality of layers (e.g., the layers of the plurality of layers other than the core adjacent layer) is less than or equal to the core refractive index. In various embodiments, the refractive index of each of the remaining layers of the plurality of layers (e.g., the layers of the plurality of layers other than the core adjacent layer) is less than the core refractive index. In an exemplary embodiment, at least one of the plurality of layers other than the core adjacent layer has a refractive index greater than the core refractive index.

[0035] In various embodiments, the cladding 120 comprises a plurality of sets of layers, where each set of layers comprises at least two layers. For example, in various embodiments, the cladding 120 comprises alternating first cladding layers 122 (e.g., 122A, 122B, 122C) and second cladding layers 124 (e.g., 124A, 124B, 124C). The refractive index of the first cladding layer 122 is different from the refractive index of the second cladding layer 124. In various embodiments, the cladding 120 comprises alternating first, second, and third cladding layers. In various embodiments, each set of layers comprises four or more layers. In various embodiments, the cladding 120 comprises a set of layers that form a distributed Bragg grating. For example, the refractive index modulation provided by the plurality of sets of layers that make up the cladding 120 and / or the grating formed by sequential alternation satisfies the Bragg condition.

[0036] In an exemplary embodiment, the first cladding layer 122 is made of a material having a first layer refractive index and / or includes a material having a first layer refractive index, and the second cladding layer 124 is made of a material having a second layer refractive index and / or includes a material having a second layer refractive index. In an exemplary embodiment, the core adjacent layer 126 is the innermost first cladding layer 122A. For example, in an exemplary embodiment, the core adjacent layer refractive index is the first layer refractive index. In various embodiments, the core refractive index is greater than the first layer refractive index. In various embodiments, the core refractive index is greater than or equal to the second layer refractive index. In an exemplary embodiment, the second refractive index is greater than the core refractive index. When the layer set includes a third layer or additional layers, the refractive index of the third layer or additional layers may be less than, equal to, or greater than the core refractive index in various embodiments. In an exemplary embodiment, the first layer refractive index (e.g., the core adjacent layer refractive index) is less than the second layer refractive index (and less than the core refractive index). In an exemplary embodiment, the second layer refractive index is less than the first layer refractive index.

[0037] In various embodiments, the first cladding layer 122 and / or the second cladding layer 124 (and / or the third cladding layer and / or additional cladding layers) include one or more of SiO2, tetraethyl orthosilicate (TEOS) SiO2, vacuum, air, etc. In an exemplary embodiment, the first cladding layer 122 and / or the second cladding layer 124 include the same material as the waveguide core 110. In an exemplary embodiment, the second cladding layer 124 includes one or more of Al2O3, Si3N4, Si (e.g., amorphous Si, polysilicon, etc.), TiO2, or HfO2.

[0038] In the illustrated embodiment, the first cladding layer 122 has a first depth d1. In an exemplary embodiment, each of the first cladding layers 122 (e.g., the first layer of each of a plurality of sets of layers) has the same first depth d1. In various embodiments, the first depth d1 is less than or equal to the coherence length of the light transmitted through the waveguide 100 in the material of the first cladding layer 122. For example, the first depth d1 may depend on the wavelength of the light transmitted through the waveguide 100. In an exemplary embodiment, one or more of the first cladding layers 122 (e.g., at least one of the first layers of a plurality of sets of layers) has a first depth d1 that is different from that of one of the other first cladding layers 122. In various embodiments, each first depth is in the range of 10 nm to 500 nm. For example, in an exemplary embodiment, each first depth is in the range of 25 nm to 120 nm.

[0039] In the illustrated embodiment, the second cladding layer 124 has a second depth d2. In an exemplary embodiment, each of the second cladding layers 124 (e.g., the second layer of each of a plurality of sets of layers) has the same second depth d2. In various embodiments, the second depth d2 is less than or equal to the coherence length of the light transmitted through the waveguide 100 in the material of the second cladding layer 124. For example, the second depth d2 may depend on the wavelength of the light transmitted through the waveguide 100. In an exemplary embodiment, one or more of the second cladding layers 124 (e.g., at least one of the second layers of a plurality of sets of layers) has a second depth d2 that is different from that of one of the other second cladding layers 124. In various embodiments, each second depth is in the range of 10 nm to 500 nm. For example, in an exemplary embodiment, each second depth is in the range of 25 nm to 120 nm.

[0040] In various embodiments, the cladding 120 is made up of a plurality of sets of layers 121. For example, in the illustrated embodiment, a first cladding layer 122A and a second cladding layer 124A form a first set of layers, a first cladding layer 122B and a second cladding layer 124B form a second set of layers, and a first cladding layer 122C and a second cladding layer 124C form a third set of layers. In various embodiments, the cladding 120 comprises from 2 to 20 sets of layers. In various embodiments, the cladding 120 comprises from 3 to 15 sets of layers. While the illustrated sets of layers include two layers (e.g., a first cladding layer 122 and a second cladding layer 124), in various embodiments, the sets of layers can include three layers, four layers, five layers, six layers, etc., as suitable for the application.

[0041] In various embodiments, the cladding 120 has a thickness of less than 3 microns. For example, in an exemplary embodiment, the cladding 120 has a thickness of 2 microns or less. In various embodiments, the thickness of the cladding is the combined thickness of a plurality of sets of layers 121. For example, if each set of layers consists of a first cladding layer 122 and a second cladding layer 124, the thickness of the cladding 120 is equal to the sum of each first depth d1 of each of the first cladding layers 122 and each second depth d2 of each of the second cladding layers 124. For example, in an exemplary embodiment, each first layer has the same first depth d1, each second layer has the same second depth d2, and the thickness of the cladding is equal to s(d1 + d2), where s is an integer indicating the number of sets of layers.

[0042] In an exemplary embodiment, the periodic layer thicknesses (e.g., d1 and d2) can vary as a function of where the layers are disposed with respect to the waveguide core 110. For example, the layer thickness can increase or decrease gradually from a core-adjacent layer (e.g., a layer immediately / directly adjacent to the waveguide core 110) to the outer surface of the cladding 120 (which interfaces with the surrounding environment).

[0043] In various embodiments, one or more isolated and / or non-repeating layers can be inserted and / or disposed between sets of repeating layer 121. For example, an isolated and / or non-repeating layer can be used to define a blocking zone that can have a larger opening angle θ. In an example, the isolated and / or non-repeating layer is a layer that is not a layer of the set of repeating layer 121 included in the plurality of layers of cladding 120. In an exemplary embodiment, the core adjacent layer is an isolated and / or non-repeating layer. In an exemplary embodiment, the outermost layer of the plurality of layers of cladding 120 is an isolated and / or non-repeating layer.

[0044] In various embodiments, the outermost surface 125 of the cladding is smoothed using a chemical mechanical polishing (CMP) process or the like.

[0045] In various embodiments, the modulated and / or periodic refractive index of cladding 120 causes the cladding to define a blocking zone in which light of a particular wavelength is scattered into cladding 120 with a reduced probability therein.

[0046] FIG. 2A illustrates a cross-sectional view of a portion of a conventional waveguide having a waveguide core 10 and a conventional cladding 20. The cross-sectional view is taken in a plane substantially parallel to the guiding propagation direction β of the waveguide. A ray of light having an electric field E (e.g., a transverse electric (TE) polarization) that propagates in the guiding propagation direction β and intersects the guiding propagation vector β is illustrated as propagating along the waveguide core 10. Generally, as a result of the process used to form the waveguide core 10, the sidewalls 15 of the waveguide core 10 are not smooth. Thus, when an optical signal interacts with the sidewalls 15, a scattering event 30 occurs. As a result of the scattering event 30, a portion of the optical signal is lost into the conventional cladding 20 as a scattered signal 40. In the conventional cladding 20, the scattered signal 40 can disappear through the conventional cladding 20 at any angle. This results in a significant optical loss due to various scattering events 30 as the optical signal propagates along the length of the conventional waveguide.

[0047] FIG. 2B illustrates a cross-sectional view of a portion of a waveguide 100 having a waveguide core 110 and a cladding 120 with a modulated and / or periodic refractive index. The cross-sectional view is taken in a plane substantially parallel to the guiding propagation direction β of the waveguide. A ray of light having an electric field E (e.g., a transverse electric (TE) polarization) that propagates in the guiding propagation direction β and intersects the guiding propagation vector β is illustrated as propagating along the waveguide core 110. Generally, as a result of the process used to form the waveguide core 110, the sidewalls 115 of the waveguide core 110 are not smooth. Thus, when an optical signal interacts with the sidewalls 115, scattering events 35 may occur. However, the modulated and / or periodic refractive index of the cladding 120 defines a blocking zone 130. Therefore, the scattered signal 140 does not disappear into the blocking zone 130. In various embodiments, the blocking zone 130 is defined by a blocking zone 135 having a vertex and an opening angle θ that are positioned at the location of the scattering event 35.

[0048] In various embodiments, the first depth d1 of the first cladding layer 122, the first refractive index of the first cladding layer 122 (e.g., the core-adjacent layer refractive index), the second depth d2 of the second cladding layer 124, the second refractive index of the second cladding layer 124, the depth and / or refractive index of any third or additional layer, etc., are configured such that, for a target wavelength or wavelengths within a target wavelength range, the scattered signal 140 is not propagated into the blocking zone by constructive or destructive interference between the transmission mode and the reflection mode.

[0049] In various embodiments, the first depth d1 of the first cladding layer 122, the first refractive index of the first cladding layer 122 (e.g., the core-adjacent layer refractive index), the second depth d2 of the second cladding layer 124, the second refractive index of the second cladding layer 124, the depth and / or refractive index of any third or additional layer, etc., are configured such that, for a target wavelength or wavelengths within a target wavelength range and wavelengths within a range of angles of incidence of the optical signal with the sidewalls 115, the scattered signal 140 is not propagated into the blocking zone by constructive or destructive interference between the transmission mode and the reflection mode.

[0050] In an exemplary embodiment, the first depth d1 of the first cladding layer 122, the first refractive index of the first cladding layer 122 (e.g., the core adjacent layer refractive index), the second depth d2 of the second cladding layer 124, the second refractive index of the second cladding layer 124, the depth and / or refractive index of any third or further layer, etc., are configured such that transmission of the optical signal into the cladding for a wide range of angles of incidence with the sidewall 115 of the optical signal is minimized for a target wavelength or wavelengths within a target wavelength range.

[0051] When the scattered signal 140 is prevented from propagating through the blocking zone 130 and / or minimized within the blocking zone 130, the optical loss corresponding to the scattered signal is significantly reduced relative to the scattered signal 40 of a similar scattering event in a waveguide having a conventional cladding 20. Thus, the waveguide 100 having a modulated and / or periodic refractive index cladding 120 provides an improvement in the field of waveguides, waveguides with low and / or reduced optical power loss, waveguide claddings, and / or similar technical fields.

[0052] Exemplary Manufacture of a Waveguide Having a Periodic Refractive Index Cladding FIG. 3 illustrates a flowchart depicting various processes, procedures, operations, etc. for manufacturing a waveguide 100 having a modulated and / or periodic refractive index according to an exemplary embodiment. Starting at step / operation 302, a waveguide layer is deposited on a substrate 105. For example, a layer of material used to form the waveguide core 110 is deposited on the substrate 105. In various embodiments, the waveguide layer is deposited on the substrate 105 using at least one of atomic layer deposition (e.g., plasma enhanced atomic layer deposition, thermal atomic layer deposition, etc.), chemical vapor deposition (e.g., plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition, etc.), or dielectric sputtering or evaporation.

[0053] In various embodiments, the substrate 105 is made of and / or includes Si or another substrate material suitable for the application. In various embodiments, the waveguide layer is made of and / or includes one or more of Al2O3, Si3N4, Si (e.g., amorphous Si, polysilicon, etc.), TiO2, or HfO2.

[0054] In step / operation 304, the waveguide core 110 is formed from the waveguide layer deposited on the substrate 105. For example, the waveguide core 110 is formed by patterning the waveguide layer and performing etching and / or lift-off steps. In various embodiments, the waveguide core 110 is formed from the waveguide layer using a photolithography or electron beam (e-beam) photolithography process followed by dielectric etching. In various embodiments, the waveguide core 110 is formed from the waveguide layer using a photoresist process followed by chemical vapor deposition (e.g., plasma-enhanced chemical vapor deposition, low-pressure chemical vapor deposition, etc.), or evaporation of the waveguide layer followed by a lift-off process. Depending on the intended application and waveguide design, various other techniques can be used to pattern and form the waveguide core 110 from the waveguide layer in various embodiments.

[0055] In an exemplary embodiment, in step / operation 306, the outer surface (e.g., sidewall 115) of the waveguide core 110 is smoothed. For example, a process can be implemented to reduce the roughness of the sidewall 115 (and / or a portion thereof) of the waveguide core 110. For example, in an exemplary embodiment, a reflow process can be implemented before dielectric etching, or a lift-off process is implemented to reduce the roughness of the sidewall 115 of the waveguide core 110. In another exemplary embodiment, short isotropic etching can be used on at least a portion of the sidewall 115 of the waveguide core 110 to reduce the roughness of at least a portion of the sidewall 115. For example, the patterned waveguide core 110 can be immersed in wet etching for a short time to round the rough features of the sidewall 115. In yet another example, the sidewall 115 can be smoothed by oxidizing at least a portion of the surface of the waveguide core 110 and then performing oxide etching.

[0056] In step / operation 308, a cladding 120 is formed around at least a portion of the waveguide core 110. In the embodiment illustrated in FIG. 1, the cladding 120 is around three surfaces or sidewalls 115 of the waveguide core 110 that are not directly adjacent to and / or in contact with the substrate 105.

[0057] In an exemplary embodiment, the cladding 120 surrounds the waveguide core 110. For example, a plurality of layers of the cladding 120 can be disposed between the waveguide core 110 and the substrate 105. For example, a plurality of layers of the cladding 120 can be deposited on the substrate before performing step / operation 302. Then, a waveguide layer can be deposited on the plurality of layers of the cladding 120. In step / operation 308, additional layers of the cladding can be formed around at least a portion of the waveguide core (e.g., to cover / surround the sides and top of the waveguide core 110).

[0058] In various embodiments, the cladding 120 is formed to have a modulated and / or periodic refractive index. In various embodiments, forming the cladding 120 includes sequentially depositing a plurality of sets of cladding layers around at least a portion of the waveguide core 110. For example, in an embodiment where a set of cladding layers consists of a first cladding layer and a second cladding layer, forming the cladding includes depositing at least partially a first cladding layer 122A (e.g., core adjacent layer 126) around the waveguide core 110, and then depositing a second cladding layer 124A on the exposed surface of the first cladding layer 122. Then another first cladding layer 122B is deposited on the second cladding layer 124A, followed by the deposition of another second cladding layer 124B on the first cladding layer 122B. The sequential alternating deposition of the cladding layers is sequentially performed until all of the plurality of sets of cladding layers are formed.

[0059] In various embodiments, the cladding layers (e.g., the first cladding layer 122 and / or the second cladding layer 124) are sequentially formed using at least one of atomic layer deposition (e.g., plasma enhanced atomic layer deposition, thermal atomic layer deposition, etc.), chemical vapor deposition (e.g., plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition, etc.).

[0060] In various embodiments, the cladding layers (e.g., the first cladding layer 122 and / or the second cladding layer 124) are sequentially formed using conformal deposition. For example, the first cladding layer 122A (e.g., core adjacent layer 126) deposited on the waveguide core 110 may be conformal to the topology of the waveguide core 110, and the second cladding layer 124B deposited on the first cladding layer 122A may be conformal to the topology of the first cladding layer 122A, and so on.

[0061] In various embodiments, the cladding layers of the plurality of sets of cladding layer 121 are sequentially formed such that the cladding 120 has a modulated and / or periodic refractive index. In various embodiments, the cladding layers of the plurality of sets of cladding layer 121 are sequentially formed such that the plurality of sets of cladding layers form a Bragg grating. As should be understood, a Bragg grating is a type of distributed Bragg reflector.

[0062] In an exemplary embodiment, following step / operation 310 of FIG. 3, the outer surface 125 of the cladding 120 is smoothed. For example, CMP or other surface smoothing processes can be used to smooth and / or reduce the roughness of the outer surface 125 of the cladding layer 120.

[0063] In an exemplary embodiment, the last cladding layer (e.g., the second cladding layer 124C) can be deposited to have a greater depth than the other (similar) cladding layers. For example, the second cladding layers 124A and 124B may have the same second depth d2, and the last cladding layer 124C may have a second depth d2 that is greater than the second cladding layers 124A and 124B. CMP can then be used to planarize the outer surface 125 of the cladding 120.

[0064] An exemplary quantum computer comprising a waveguide having a periodic refractive index cladding Waveguides are used in a variety of situations. One exemplary situation is in various quantum computing systems. One such exemplary quantum computing system comprises a quantum charge coupled device (QCCD)-based quantum computer. FIG. 4 provides a schematic diagram of an exemplary quantum computer system 400 comprising at least one optical path 466 (466A, 466B, 466C) that is at least partially defined by a waveguide 100 having a periodic refractive index cladding 120. In various embodiments, the quantum computer system 400 comprises a computing entity 410 and a quantum computer 450. In various embodiments, the quantum computer 450 comprises a controller 430, a cryogenic and / or vacuum chamber 440 enclosing an ion trap 445, and one or more operation source(s) 464 (e.g., 464A, 464B, 464C). In an exemplary embodiment, the one or more operation source(s) 464 can comprise one or more lasers (e.g., UV laser, visible light laser, microwave laser, etc.). In various embodiments, the one or more operation source(s) 464 are configured to manipulate and / or effect the generation of a controlled quantum state of one or more ions within the ion trap 445. For example, in an exemplary embodiment where the one or more operation source(s) 464 comprise one or more lasers, the lasers can provide one or more laser beams to the ion trap 445 within the cryogenic and / or vacuum chamber 440. Each of the one or more operation source(s) 464 provides a laser beam or the like to the ion trap 445 via a corresponding optical path 466 (e.g., 466A, 466B, 466C). In various embodiments, at least one optical path 466 comprises a waveguide 100 having a modulated and / or periodic refractive index cladding 120. Via the waveguide 100, the operation source 464 can provide a modulated beam to the ion trap 445 via the optical path 466.

[0065] In various embodiments, the computing entity 410 is configured to enable a user to provide inputs to the quantum computer 450 (e.g., via a user interface of the computing entity 410), and to receive and view outputs from the quantum computer 450. The computing entity 410 can communicate with the controller 430 of the quantum computer 450 via one or more wired or wireless networks 420, and / or via direct wired and / or wireless communication. In an exemplary embodiment, the computing entity 410 can convert, configure, format, etc., information / data, quantum computing algorithms, etc., into a computing language, executable instructions, command sets, etc., that can be understood and / or implemented by the controller 430.

[0066] In various embodiments, the controller 430 is configured to control an electrical signal source and / or driver, a cryogenic system and / or a vacuum system that controls the temperature and pressure within the cryogenic and / or vacuum chamber 440, an operation source 464, and / or other systems configured to control the environmental conditions (e.g., temperature, humidity, pressure, etc.) within the cryogenic and / or vacuum chamber 440 and / or to manipulate and / or effect the generation of a controlled quantum state of one or more ions within the ion trap 445. In various embodiments, the ions trapped within the ion trap 445 are used as qubits of the quantum computer 450.

[0067] Exemplary controller In various embodiments, a waveguide 100 having a modulated and / or periodic refractive index cladding 120 is incorporated into a quantum computer 450. In various embodiments, the quantum computer 450 further includes a controller 430 configured to control various elements of the quantum computer 450. For example, the controller 430 can be a voltage source and / or driver configured to provide an electrical signal that controls the modulation of one or more beams via a corresponding modulator, a cryogenic and / or vacuum system configured to control the temperature and pressure within a cryogenic and / or vacuum chamber 440, an operation source 464, and / or another system configured to control the environmental conditions (e.g., temperature, humidity, pressure, etc.) within the cryogenic and / or vacuum chamber 440 and / or to manipulate and / or effect the generation of a controlled quantum state of one or more ions within an ion trap 445.

[0068] As shown in FIG. 5, in various embodiments, the controller 430 can include various controller elements including a processing element 505, a memory 510, a driver controller element 515, a communication interface 520, an analog-to-digital converter element 525, etc. For example, the processing element 505 can include a programmable logic device (CPLD), a microprocessor, a coprocess entity, an application-specific instruction set processor (ASIP), an integrated circuit, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a programmable logic array (PLA), a hardware accelerator, other processing devices and / or circuits, etc., and / or a controller. The term circuit can refer to an embodiment that is entirely hardware or a combination of hardware and a computer program product. In an exemplary embodiment, the processing element 505 of the controller 430 includes a clock and / or communicates with a clock.

[0069] For example, the memory 510 can include a non-transitory memory such as a volatile and / or non-volatile memory storage device, such as one or more of a hard disk, ROM, PROM, EPROM, EEPROM, flash memory, MMC, SD memory card, memory stick, CBRAM, PRAM, FeRAM, RRAM, SONOS, racetrack memory, RAM, DRAM, SRAM, FPM DRAM, EDO DRAM, SDRAM, DDR SDRAM, DDR2 SDRAM, DDR3 SDRAM, RDRAM, RIMM, DIMM, SIMM, VRAM, cache memory, register memory, and the like. In various embodiments, the memory 510 can store qubit recordings (e.g., in a qubit recording data store, qubit recording database, qubit recording table, etc.) corresponding to the qubits of a quantum computer, calibration tables, executable queues, computer program code (e.g., in one or more computer languages, dedicated controller languages, etc.). In an exemplary embodiment, at least a portion of the computer program code stored in the memory 510, when executed (e.g., by the processing element 505), causes the controller 430 to perform one or more of the steps, operations, processes, procedures, etc. described herein to track the phase of atomic objects within the atomic system and thereby effect adjustment of the phase of one or more operation sources and / or signals generated thereby.

[0070] In various embodiments, the driver controller element 515 can include one or more driver and / or controller elements each configured to control one or more drivers. In various embodiments, the driver controller element 515 can comprise a driver and / or a driver controller. For example, the driver controller can be configured to cause one or more corresponding drivers to operate in accordance with executable instructions, commands, etc. that the controller 430 (e.g., the processing element 505) has scheduled for execution. In various embodiments, the driver controller element 515 may be capable of causing the operation source 464 to operate by the controller 430. In various embodiments, the driver can be a laser driver, a vacuum component driver, a driver for controlling the current and / or voltage flow of an electrical signal applied to the electrodes of the ion trap 445, a cryogenic and / or vacuum system component driver, etc. In various embodiments, the controller 430 comprises means for communicating and / or receiving signals from one or more light-receiving components such as a camera, a MEMs camera, a CCD camera, a photodiode, a photomultiplier tube, etc. For example, the controller 430 can comprise one or more analog-to-digital converter elements 525 configured to receive signals from one or more light-receiving components, calibration sensors, etc.

[0071] In various embodiments, the controller 430 can comprise a communication interface 520 for interfacing and / or communicating with the computing entity 410. For example, the controller 430 can comprise a communication interface 520 for receiving executable instructions, command sets, etc. from the computing entity 410 and providing the output received from the quantum computer 450 (e.g., from the light collection system) and / or the result of processing the output to the computing entity 410. In various embodiments, the computing entity 410 and the controller 430 can communicate directly via wired and / or wireless communication and / or via one or more wired and / or wireless networks 420.

[0072] Exemplary computing entity FIG. 6 provides a schematic diagram representing an exemplary computing entity 410 that can be used in conjunction with embodiments of the present invention. In various embodiments, the computing entity 410 is configured to enable a user to provide inputs to (e.g., via a user interface of the computing entity 410) and receive, display, analyze, etc., outputs from the quantum computer 450.

[0073] As shown in FIG. 6, each computing entity 410 can include an antenna 612, a transmitter 604 (e.g., wireless), a receiver 606 (e.g., wireless), and a processing element 608 that respectively provide signals to the transmitter 604 and receive signals from the receiver 606. The signals provided to the transmitter 604 and received from the receiver 606 can each include signaling information / data compliant with the wireless interface standards of a suitable wireless system that communicates with various entities such as the controller 430, other computing entities 410, etc. In this regard, the computing entity 410 may be capable of operating with one or more wireless interface standards, communication protocols, modulation types, and access types. For example, the computing entity 410 can be configured to receive and / or provide communications using a wired data transmission protocol such as Fiber Distributed Data Interface (FDDI), Digital Subscriber Line (DSL), Ethernet, Asynchronous Transfer Mode (ATM), Frame Relay, DOCSIS (Data Over Cable Service Interface Specification), or any other wired transmission protocol.Similarly, the computing entity 410 can be configured to communicate via a wireless external communication network that uses any of a variety of protocols, such as General Packet Radio Service (GPRS), Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access 2000 (CDMA2000), CDMA2000 1X (1xRTT), Wideband Code Division Multiple Access (WCDMA (registered trademark)), Global System for Mobile Communications (GSM), GSM Enhanced Data rates for GSM Evolution (EDGE), Time Division-Synchronous Code Division Multiple Access (TD-SCDMA), Long Term Evolution (LTE), E-UTRAN (Evolved Universal Terrestrial Radio Access Network), EVDO (Evolution-Data Optimized), High Speed Packet Access (HSPA), High Speed Downlink Packet Access (HSDPA), IEEE 802.11 (Wi-Fi), Wi-Fi Direct, 802.16 (WiMAX), Ultra Wideband (UWB), Infrared (IR) protocol, Near Field Communication (NFC) protocol, Wibree, Bluetooth protocol, Wireless Universal Serial Bus (USB) protocol, and / or any other wireless protocol.The computing entity 410 can use such protocols and standards to communicate using, for example, Border Gateway Protocol (BGP), Dynamic Host Configuration Protocol (DHCP), Domain Name System (DNS), File Transfer Protocol (FTP), Hypertext Transfer Protocol (HTTP), HTTP over TLS / SSL / Secure, Internet Message Access Protocol (IMAP), Network Time Protocol (NTP), Simple Mail Transfer Protocol (SMTP), Telnet, Transport Layer Security (TLS), Secure Sockets Layer (SSL), Internet Protocol (IP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Datagram Congestion Control Protocol (DCCP), Stream Control Transmission Protocol (SCTP), Hypertext Markup Language (HTML), and the like.

[0074] Through these communication standards and protocols, the computing entity 410 can communicate with various other entities using concepts such as Unstructured Supplementary Service Information / Data (USSD), Short Message Service (SMS), Multimedia Message Service (MMS), Dual-Tone Multi-Frequency signaling (DTMF), and / or Subscriber Identity Module Dial (SIM Dial). The computing entity 410 can also download changes, add-ons, and updates to its firmware, software (including, for example, executable instructions, applications, program modules), and operating system. In various embodiments, the computing entity 410 includes a network interface 620 configured to communicate via one or more wired and / or wireless networks 420.

[0075] The computing entity 410 can also include a user interface device having one or more user input / output interfaces (e.g., a display 616 and / or speaker / speaker driver coupled to the processing element 608, and a touch screen, keyboard, mouse, and / or microphone coupled to the processing element 608). For example, the user output interface can execute on the computing entity 410 interchangeably with applications, browsers, user interfaces, interfaces, dashboards, screens, web pages, pages and / or similar terms used herein, and / or be accessible via the computing entity 410 to cause display or audible presentation of information / data and to configure interaction therewith via one or more user input interfaces. The user input interface can include any of several devices that enable the computing entity 410 to receive data, such as a keypad 618 (hard or soft), a touch display, a voice / speech or motion interface, a scanner, a reader, or other input device. In embodiments including the keypad 618, the keypad 618 can include (or display) normal numbers (0-9) and associated keys (#, *), and other keys used to operate the computing entity 410, and can include a set of keys that can be used to implement an alphabetical key set or an alphabetical key set. In addition to providing input, the user input interface can be used to activate or deactivate certain functions, such as a screen saver and / or sleep mode. Through such input, the computing entity 410 can collect information / data, user interaction / input, and the like.

[0076] The computing entity 410 can also include a volatile memory device or memory 622 and / or a non-volatile memory device or memory 624, which can be incorporated and / or can be removable. For example, the non-volatile memory can be a ROM, PROM, EPROM, EEPROM, flash memory, MMC, SD memory card, memory stick, CBRAM, PRAM, FeRAM, RRAM, SONOS, racetrack memory, etc. The volatile memory can be a RAM, DRAM, SRAM, FPM DRAM, EDO DRAM, SDRAM, DDR SDRAM, DDR2 SDRAM, DDR3 SDRAM, RDRAM, RIMM, DIMM, SIMM, VRAM, cache memory, register memory, etc. The volatile and non-volatile memory devices or memories can store databases, database instances, database management system entities, data, applications, programs, program modules, scripts, source code, object code, bytecode, compiled code, interpreter code, machine code, executable instructions, etc., to implement the functions of the computing entity 410.

[0077] Conclusion Although many modifications and other embodiments of the invention described herein will come to mind to those skilled in the art, the invention is related to them and has the benefits of the teachings presented in the above description and related drawings. Therefore, it should be understood that the invention should not be limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims. Specific terms are employed herein, but they are used only in a general descriptive sense and not for purposes of limitation.

Description of Reference Numerals

[0078] 10 Waveguide core 15 Sidewall 20 Conventional cladding 30 Scattering event 35 Scattering event 40 Scattered signal 100 Waveguide 105 Substrate 110 Waveguide Core 115 Side Wall 120 Cladding 121 Layer 122 First Cladding Layer 122A First Cladding Layer 122B First Cladding Layer 122C First Cladding Layer 124 Second Cladding Layer 124A Second Cladding Layer 124B Second Cladding Layer 124C Second Cladding Layer 125 Surface, Outer Surface 126 Core Adjacent Layer 130 Blocking Zone 135 Blocking Zone 140 Scattered Signal 400 Quantum Computer System 410 Computational Entity 420 Wired or Wireless Network 430 Controller 440 Low Temperature and / or Vacuum Chamber 445 Ion Trap 450 Quantum Computer 464 Operation Generation Source 464A Operation Generation Source 464B Operation Generation Source 464C Operation Generation Source 466 Optical Path 466A Optical Path 466B Optical Path 466C Optical Path 505 Processing Element 510 Memory 515 Driver Controller Element 520 Communication Interface 525 Analog-to-Digital Converter Element, A / D Converter 604 Transmitter 606 Receiver 608 Processing Element 612 Antenna 612 616 Display 618 Keypad 620 Network Interface 622 Volatile Memory 624 Non-volatile Memory

Claims

1. An optical waveguide core having a core refractive index, A cladding disposed around at least a part of the periphery of the optical waveguide core, the cladding comprising a plurality of layers defining a periodic refractive index, Comprising, The plurality of layers include a core adjacent layer having a core adjacent layer refractive index, An optical waveguide in which the core refractive index is greater than the core adjacent layer refractive index.

2. An optical waveguide according to claim 1, wherein the cladding defines a blocking zone in which the probability of light having a target wavelength or light within a target wavelength range scattering into the cladding is reduced therein.

3. An optical waveguide according to claim 1, wherein the cladding has a thickness of 2 microns or less.

4. The plurality of layers include a plurality of sets of layers, each of the plurality of sets of layers includes at least a first cladding layer and a second cladding layer, the first cladding layer has a first layer refractive index, the second cladding layer has a second layer refractive index, and the core refractive index is greater than at least one of the first layer refractive index or the second layer refractive index. An optical waveguide according to claim 1.

5. An optical waveguide according to claim 4, wherein the depth of each of the second cladding layers is in the range between 25 nm and 120 nm, and the depth of each of the first cladding layers is in the range between 25 nm and 120 nm.

6. An optical waveguide according to claim 4, wherein the plurality of sets of layers include 3 to 15 sets of layers, and each of the sets of layers includes at least one of the first cladding layers and one of the second cladding layers.

7. An optical waveguide according to claim 4, wherein the first layer refractive index and the second layer refractive index are different from each other.

8. At least one of the first cladding layer or the second cladding layer contains SiO ２ , TEOS SiO ２ , vacuum, air, Al ２ O ３ , Si ３ N ４ , Si, TiO ２ , or HfO ２ The waveguide according to claim 1, comprising

9. An optical waveguide according to claim 1, wherein the cladding is a distributed Bragg grating cladding.

10. The waveguide core contains Al ２ O ３ , Si ３ N ４ , Si, TiO ２ , or HfO ２ The waveguide according to claim 1, comprising one or more of these.

11. An optical waveguide according to claim 1, wherein the optical waveguide core is formed on a substrate.

12. A method for manufacturing an optical waveguide, Forming an optical waveguide core, the optical waveguide core having a core refractive index, Forming a cladding around at least a part of the optical waveguide core, the cladding comprising a plurality of layers defining a periodic refractive index, Including, The plurality of layers include a core adjacent layer having a core adjacent layer refractive index, A method in which the core refractive index is greater than the core adjacent layer refractive index.

13. The method according to claim 12, further comprising, before the step of forming the clad, performing a smoothing operation on one or more surfaces of the waveguide core.

14. The method according to claim 12, wherein the step of forming the waveguide core includes depositing a waveguide core material on a substrate using at least one of atomic layer deposition, chemical vapor deposition, or dielectric sputtering or evaporation.

15. The step of forming the waveguide core (a)photolithography or electron beam lithography, followed by dielectric etching, or (b)a photoresist, followed by chemical vapor deposition or evaporation of a waveguide layer formed from the waveguide core material, followed by lift-off The method according to claim 14, further comprising patterning the waveguide core from the waveguide core material using one of the above.

16. The method according to claim 15, further comprising performing a reflow process of the photoresist before the dielectric etching or the lift-off to reduce the roughness of the sidewalls of the waveguide core.

17. The method according to claim 12, wherein the step of forming the clad includes sequentially depositing at least a first clad layer and a second clad layer around at least a part of the waveguide core to form a plurality of sets of clad layers around at least a part of the waveguide core.

18. The method according to claim 17, wherein the first clad layer and the second clad layer are sequentially formed using at least one of atomic layer deposition or chemical vapor deposition.

19. The method according to claim 17, wherein the first clad layer and the second clad layer are formed by conformal deposition.

20. The method according to claim 12, further comprising performing chemical mechanical polishing on the outer surface of the clad.

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