optofluidic devices

Abstract

Disclosed herein is a waveguide structure and a method for fabricating a waveguide structure (100) comprising: a waveguide layer comprising a first oxide layer (108), a second oxide layer (110) adjacent to the first oxide layer, a third oxide layer (112) opposite the first oxide layer and adjacent to the second oxide layer, and an oxide strip (114) adjacent to the second oxide layer and extending at least partially into the third oxide layer, wherein the first, second, and third oxide layers and the oxide strip form a ridge waveguide; a fluidic channel (122) extending through at least a portion of the first, second, and third oxide layers and intersecting the ridge waveguide, such that light (128) carried by the ridge waveguide is incident on the fluidic channel; and a cover layer (124) bonded to the waveguide layer and surrounding the fluidic channel.

Description

[Technical Field]

[0001] This disclosure relates generally to waveguide architectures, and more particularly to two-dimensional waveguide structures, including optofluidic chips with optical waveguides fabricated without (or with minimal) use of air gaps. [Background technology]

[0002] Waveguide structures such as optical and optofluidic chips are of great importance in modern biomedical research. For example, optical and optofluidic chips (e.g., lab-on-a-chip devices) have applications in biochemical analysis, treatment, and point-of-care (POC) diagnostic devices. Lab-on-a-chip devices have been found to improve the ability to detect particulates within integrated systems without the use of external bulky optical elements. These waveguide structures can comprise solid-core waveguides, fluidic channels, and / or fluidic-core waveguides, which can be coplanar with one another and can intersect one another in various configurations.

[0003] Known techniques for fabricating such structures require multiple fabrication steps. For example, known techniques for fabricating waveguide chips may include six or more lithography steps, multiple etching steps, multiple deposition steps, and a sacrificial core removal process. Furthermore, known techniques for fabricating waveguide structures may include fabricating an optical waveguide by etching (or otherwise forming) an air gap surrounding the waveguide core. Light is guided through the waveguide due to the difference in refractive index of the material forming the waveguide core compared to the surrounding air in the air gap. Summary of the Invention [Problem to be solved by the invention]

[0004] As discussed above, recent developments in the field of optofluidics have led to advances in biomedical research by integrating optofluidic components into miniaturized systems and achieving a high level of tunability handled by reconfigurable optofluidic components, resulting in highly adaptable and simplified waveguide architectures. Despite these advances, however, the predictability of optical properties in waveguide structures remains uncertain, hindering the application of waveguide structures in analysis and diagnostics. For example, previous studies have demonstrated the difficulty of focusing optical beams (especially those with high numerical apertures) using optofluidic components, at least due to the fact that the structural materials of waveguide structures often have very high refractive indices (e.g., 1.3-1.6). Furthermore, known techniques for fabricating waveguide structures, such as optical and optofluidic chips, require multiple steps, which also hinders the application of optofluidic chips. The fabrication steps are difficult, complex, time-consuming, and expensive to perform. For example, as discussed above, waveguide structures often require etching an air gap into the waveguide structure surrounding the waveguide core. Additionally, the alignment steps in the fabrication of optofluidic chips introduce various opportunities for defects and failures in the waveguide structures due to potential misalignment in miniaturized systems.

[0005] Air gaps have been a key component in waveguide structures because they contribute to the propagation of light through the waveguide (e.g., due at least in part to the difference in refractive index between air and the solid components of the waveguide adjacent to the air gap). Nevertheless, air gaps present challenges in the use of optofluidic chips because they cause light leakage between closely bonded fluid layers during use. Furthermore, etch-induced depressions in the waveguide structure, such as air gaps, impair the bondability and / or joinability of the fluid layers in the waveguide chip.

[0006] Therefore, in fields utilizing waveguide structures, such as optical and optofluidic chips, there is a need to develop simple, optimized waveguide architectures that limit light leakage as it propagates through the waveguide structures and improve the predictability (e.g., repeatability) of the systems. Furthermore, there is a need to reduce the number of steps and processes for fabricating such optimized chips and structures to improve overall manufacturability, cost, yield, and repeatability. [Means for solving the problem]

[0007] Disclosed herein are improved techniques and structures that can address one or more of the above needs. The waveguide structures provided herein can reduce light leakage between closely bonded fluid layers by eliminating air gaps from the waveguide architecture. In some embodiments, the waveguide structures can improve the predictability and reproducibility of light traveling through an optofluidic chip by introducing buried waveguide structures that can include oxide strips disposed within an oxide layer of the waveguide structure, where the oxide layer and the oxide strip have distinct refractive indices. Buried waveguide structures can produce single-mode waveguides with more reproducible and predictable light intensity cross-sections. Additionally, the non-air-gap waveguide structures disclosed herein can be positioned adjacent to (e.g., at the edge of) a fluidic channel. Placing a non-air-gap waveguide structure in close proximity to a fluidic channel can improve the predictability of light within the channel.

[0008] In some embodiments, as described herein, a single lithography / etching process, followed by a bonding process, can replace the cumbersome and extensive series of steps required by previous techniques. The reduction in the overall number of steps can enable faster, more efficient, less complex, and cheaper production (e.g., manufacturability, cost, yield, reproducibility), including on a commercial scale. The techniques described herein can require fewer microfabrication steps than known methods, enable direct fluidic integration (e.g., planar chip surfaces can enable bonding techniques and simpler fluidic interconnects), eliminate the need for time-consuming etching steps, and allow for a wider variety of materials to choose from, not just those compatible with conventional methods.

[0009] Additionally, fabricating optical waveguide structures without the use of air gaps (e.g., formed by etching) surrounding the waveguide core can simplify manufacturing and improve bondability and joinability between fluid layers. Furthermore, eliminating the air gaps can allow waveguide structure components, such as cover layers, to be effectively and easily attached (e.g., bonded) to the uniform surface of the structure's waveguide layer. For example, the top surface of a waveguide layer formed from multiple oxide layers can be a uniform, flat surface unimpeded by air gaps etched into the waveguide layer, and thus a cover layer can be easily and effectively bonded to the flat top surface without concern that the air gaps will compromise the integrity of the bond or that adhesives or other foreign matter will enter the air gaps and impair the optical properties of the waveguide.

[0010] In some embodiments, a waveguide structure is provided, the waveguide structure comprising: a waveguide layer comprising a first oxide layer, a second oxide layer adjacent to the first oxide layer, a third oxide layer adjacent to the second oxide layer opposite the first oxide layer, and an oxide strip adjacent to the second oxide layer and extending at least partially into the third oxide layer, wherein the first, second, and third oxide layers and the oxide strip form a ridge waveguide; a fluid channel extending through at least a portion of the first, second, and third oxide layers and the oxide strip and intersecting the ridge waveguide, such that light carried by the ridge waveguide is incident on the fluid channel; and a cover layer bonded to the waveguide layer and surrounding the fluid channel.

[0011] In some embodiments, the second oxide layer and the oxide strip each have a first refractive index.

[0012] In some embodiments, the first and third oxide layers each have a second refractive index that is lower than the first refractive index.

[0013] In some embodiments, the waveguide structure includes an aperture layer adjacent to the waveguide layer.

[0014] In some embodiments, the aperture layer comprises chromium, nickel, another metal, and / or one or more anti-resonance reflective optical waveguide (ARROW) layers.

[0015] In some embodiments, the aperture layer is configured to allow light to pass through one or more apertures in the aperture layer, the one or more apertures being aligned with the fluid channels.

[0016] In some embodiments, the waveguide structure includes a substrate layer adjacent to the aperture layer and opposite the waveguide layer.

[0017] In some embodiments, the substrate layer comprises one or more materials selected from the group: silicon, silica, and glass.

[0018] In some embodiments, the substrate layer includes etched regions aligned with one or more apertures in the aperture layer.

[0019] In some embodiments, the substrate layer includes an oxide sealing layer.

[0020] In some embodiments, the etched region includes a lens element configured to focus light that leaks from the fluidic channel into the etched region.

[0021] In some embodiments, the cover layer is affixed to the waveguide layer at a location adjacent to the ridge waveguide.

[0022] In some embodiments, the cover layer includes one or more apertures aligned with the fluid channels.

[0023] In some embodiments, a waveguide structure is provided, the waveguide structure comprising: a waveguide layer comprising a first oxide layer, a second oxide layer adjacent to the first oxide layer, a third oxide layer adjacent to the second oxide layer opposite the first oxide layer, and an oxide strip disposed within the second oxide layer, wherein the first, second, and third oxide layers and the oxide strip form a buried waveguide; a fluid channel extending through at least a portion of the first, second, and third oxide layers and the oxide strip and intersecting the buried waveguide, such that light carried by the buried waveguide is incident on the fluid channel; and a cover layer affixed to the waveguide layer and surrounding the fluid channel.

[0024] In some embodiments, the first, second, and third oxide layers each have a first refractive index.

[0025] In some embodiments, the oxide strip has a second refractive index that is higher than the first refractive index.

[0026] In some embodiments, the cover layer is affixed to the waveguide layer at a location adjacent to the buried waveguide.

[0027] In some embodiments, a waveguide structure is provided, the waveguide structure comprising: a waveguide layer comprising a first oxide layer, a second oxide layer adjacent to the first oxide layer, a third oxide layer opposite the first oxide layer and adjacent to the second oxide layer, and an oxide strip adjacent to the second oxide layer and extending at least partially into the third oxide layer, wherein the first, second, and third oxide layers and the oxide strip form a strip-loaded waveguide; a fluid channel extending through at least a portion of the first, second, and third oxide layers and the oxide strip and intersecting the strip-loaded waveguide, such that light carried by the strip-loaded waveguide is incident on the fluid channel; and a cover layer affixed to the waveguide layer and surrounding the fluid channel.

[0028] In some embodiments, the first oxide layer and the oxide strip each have a first refractive index.

[0029] In some embodiments, the second oxide layer has a second refractive index that is higher than the first refractive index.

[0030] In some embodiments, the third oxide layer has a third refractive index that is higher than the first refractive index and lower than the second refractive index.

[0031] In some embodiments, the first oxide layer has a first refractive index.

[0032] In some embodiments, the oxide strip has a second refractive index different from the first refractive index.

[0033] In some embodiments, the cover layer is affixed to the waveguide layer at a location adjacent to the strip-loaded waveguide.

[0034] In some embodiments, a waveguide structure is provided, the waveguide structure comprising: a waveguide layer comprising: a first oxide layer; a second oxide layer adjacent to the first oxide layer; a third oxide layer adjacent to the second oxide layer on an opposite side of the first oxide layer; and at least two oxide ribs disposed adjacent to the second oxide layer and extending at least partially into the third oxide layer, wherein the first, second, and third oxide layers and the at least two oxide ribs form a slot waveguide between the at least two oxide ribs; a fluid channel extending through at least a portion of the first, second, and third oxide layers and the at least two oxide ribs and intersecting the slot waveguide, such that light carried by the slot waveguide is incident on the fluid channel; and a cover layer bonded to the waveguide layer and surrounding the fluid channel.

[0035] In some embodiments, the first and third oxide layers each have a first refractive index.

[0036] In some embodiments, the second oxide layer and the at least two oxide ribs each have a second refractive index that is lower than the first refractive index.

[0037] In some embodiments, the cover layer is affixed to the waveguide layer at a location adjacent to the slot waveguide.

[0038] In some embodiments, a waveguide structure is provided, the waveguide structure comprising: a waveguide layer including a waveguide; and a fluid enclosure extending through at least a portion of the waveguide layer and intersecting the waveguide, such that light carried by the waveguide is incident on the fluid enclosure, the fluid enclosure including an imaging region and a non-imaging region.

[0039] In some embodiments, the waveguide structure includes an aperture layer adjacent to the waveguide layer, the aperture layer including a light blocking region disposed adjacent to a non-imaging region in the fluid enclosure and one or more apertures disposed adjacent to an imaging region in the fluid enclosure.

[0040] In some embodiments, the waveguide layer comprises multiple oxide layers.

[0041] In some embodiments, the fluid enclosure extends through at least a portion of one or more of the oxide layers of the waveguide layer.

[0042] In some embodiments, the waveguide structure comprises at least one device configured to generate turbulence to induce flow between the non-imaging region and the imaging region in the fluid container, selected from the following set: agitation device, a stirrer, a mixer, a pump, and an ultrasonic disrupter.

[0043] In some embodiments, the waveguide structure includes a substrate layer on the opposite side of the aperture layer from the waveguide layer.

[0044] In some embodiments, the waveguide structure comprises a sensor configured to capture image data of particles suspended within an imaging region of the container when the particles are illuminated or excited by light carried by the waveguide.

[0045] In some embodiments, the waveguide structure comprises an oxide strip disposed in the waveguide layer, the oxide strip having a first refractive index.

[0046] In some embodiments, at least a portion of the waveguide layer has a second refractive index that is different from the first refractive index.

[0047] In some embodiments, the fluid enclosure extends through at least a portion of an oxide strip disposed within the waveguide layer.

[0048] In some embodiments, the waveguide structure comprises at least two oxide ribs disposed in the waveguide layer, the at least two oxide ribs having a first refractive index.

[0049] In some embodiments, at least a portion of the waveguide layer has a second refractive index that is different from the first refractive index.

[0050] In some embodiments, the fluid enclosure extends through at least a portion of at least two of the oxide ribs disposed in the waveguide layer.

[0051] In some embodiments, a method of fabricating a waveguide structure is provided, the method including: disposing a waveguide layer adjacent to a substrate layer, the waveguide layer including one or more oxide layers forming waveguides, the waveguide layer having a planar upper surface; etching fluid channels in the waveguide layer by etching through a portion of the planar upper surface of the waveguide layer, the fluid channels intersecting at least one of the one or more oxide layers of the waveguide layer; and disposing a cover layer adjacent to the waveguide layer, the cover layer covering the etched fluid channels and being adhered to the waveguide layer adjacent to the waveguides.

[0052] The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0053] [Figure 1A] 1 shows a schematic diagram of a waveguide structure according to some embodiments. [Figure 1B] 1 shows a schematic diagram of a waveguide structure according to some embodiments. [Figure 1C] 1 shows a schematic diagram of a waveguide structure according to some embodiments. [Figure 1D] 1 shows a schematic diagram of a waveguide structure according to some embodiments. [Figure 1E] 1 shows a schematic diagram of a waveguide structure according to some embodiments. [Figure 2A] 1 shows a schematic diagram of a waveguide structure with a fluid reservoir according to some embodiments. [Figure 2B] 1 shows a schematic diagram of a waveguide structure with a fluid reservoir according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0054] Reference will now be made in detail to implementations and embodiments of the various aspects and variations of the systems and methods described herein. While several exemplary variations of the systems and methods are described herein, other variations of the systems and methods can include aspects of the systems and methods described herein combined in any suitable manner, having all or some combination of the described aspects.

[0055] In the description of various embodiments that follows, it should be understood that the singular forms "a," "an," and "the," as used in the description below, are intended to include the plural forms unless the content clearly dictates otherwise. Also, as used herein, the term "and / or" should be understood to refer to and include any and all combinations of one or more of the associated listed items. Furthermore, it should be understood that the terms "comprises," "including," "comprises," and / or "comprising," as used herein, indicate the presence of stated features, integers, steps, operations, elements, components, and / or units, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, units, and / or groups thereof.

[0056] The waveguide structures provided herein can reduce light leakage between closely bonded fluid layers by eliminating air gaps from the waveguide architecture. The no-air-gap waveguide structures and fabrication methods can improve the predictability and reproducibility of light traveling through optofluidic chips and reduce the number of steps previously required to fabricate a waveguide architecture. In some embodiments, the disclosed waveguide structures can include buried waveguide structures in which an oxide strip is disposed within an oxide layer of the waveguide structure, the oxide layer and the oxide strip having distinct refractive indices. The buried waveguide structures can produce single-mode waveguides with more reproducible and predictable light intensity cross-sections.

[0057] Additionally, the non-air-gap waveguide structures disclosed herein can be placed at the edges of fluidic channels. Placing non-air-gap waveguide structures adjacent to a fluidic channel can improve the predictability of light within the channel.

[0058] In some embodiments, fabrication of the optofluidic chips described herein may require a simple lithography / etching process followed by a bonding process, rather than the cumbersome and extensive series of steps required by previous techniques. For example, a waveguide structure (e.g., a two-dimensional waveguide structure) can be formed from a chip including a substrate layer and a waveguide layer over the substrate layer. In some embodiments, the substrate layer can be formed from silicon, silica, glass, a polymer, or other suitable material, and the waveguide layer can be formed from one or more oxides, such as silicon oxide, plasma-enhanced chemical vapor deposition (PECVD) oxide, low-temperature oxide, phosphorus-doped oxide, silicon oxynitride, or other suitable material. The waveguide layer can have a thickness of 1 μm, 5 μm, 10 μm, or 20 μm or more in some embodiments. The waveguide layer can have a thickness of 1 μm, 5 μm, 10 μm, or 20 μm or less in some embodiments. The materials used in the waveguide layers can be selected so that the materials effectively transmit light and can form both the solid core of a solid core waveguide and the walls of the fluid channel / container and / or the walls of the fluid core waveguide. The waveguide layers can include optical waveguides including, for example, ridge waveguides, buried waveguides, strip-loaded waveguides, and / or slot waveguides, each of which is described in further detail with reference to Figures 1A-1E herein. The waveguide layers disclosed herein can include a waveguide core region, a cladding region, and a surrounding (e.g., boundary) region disposed within the optical waveguide structure.

[0059] After the waveguide layer is disposed (e.g., laid or deposited) on the substrate layer, one or more etching steps can be performed to form one or more fluid channels and / or fluid reservoirs (which in some embodiments may also be fluid core waveguides). To form the fluid channels and / or reservoirs, cavities for the fluid channels or reservoirs can be etched away from the waveguide layer.

[0060] In some embodiments, the dimensions of the fluid channels and / or fluid reservoirs can be varied to affect the flow rate of the fluid through the fluid channels and / or fluid reservoirs. In some embodiments, the flow of fluid through the fluid channels and / or fluid reservoirs can be induced by one or more of vacuum, positive pressure, stirring devices, agitators or pumps, electroosmosis, and / or electrophoresis. In some embodiments, analytes in the fluid can reach and be measured at a detection zone of the chip passively (e.g., by diffusion). In some embodiments, the geometry of the fluid channels can be configured to induce flow focusing via sheath flow. In some embodiments, the height and / or width of the fluid channels can be 0.25 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 25 μm, 50 μm, 100 μm, 250 μm, 500 μm, or 1000 μm or less. In some embodiments, the height and / or width of the fluidic channels can be 0.25 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 25 μm, 50 μm, 100 μm, 250 μm, 500 μm, or 1000 μm or more. In some embodiments, the flow rate through the fluidic channels can be 0.005 μL / min, 0.01 μL / min, 0.1 μL / min, 1 μL / min, 10 μL / min, 100 μL / min, or 500 μL / min or less. In some embodiments, the flow rate through the fluidic channels can be 0.005 μL / min, 0.01 μL / min, 0.1 μL / min, 1 μL / min, 10 μL / min, 100 μL / min, or 500 μL / min or more.

[0061] In some embodiments, the waveguide structure can include a fluid reservoir that can remain open on at least one side (e.g., the top) during use. In some embodiments, as described in more detail below, the fluid reservoir can be at least partially sealed by a cover layer adjacent to (e.g., over) the fluid reservoir. In some embodiments, the fluid channel can be configured for fluid flow in a primary flow direction along the length of the channel, while flow in the fluid reservoir may not flow in a single primary direction and / or may not flow at all. In some embodiments, the dimensions of the fluid reservoir can be significantly larger, e.g., laterally, than the dimensions of the fluid channel. For example, as described above, the fluid reservoir can be two, three, four, or five times wider or more than the fluid channel of the waveguide structure. In some embodiments, the fluid reservoir can be two, three, four, or five times wider or less than the fluid channel of the waveguide structure. In some embodiments, the height and / or width of the fluid reservoir can be between 100 μm and 10 mm. In some embodiments, the height and / or width of the fluid container can be 50 μm, 75 μm, 100 μm, 125 μm, or 150 μm or more. In some embodiments, the height and / or width of the fluid container can be 5 mm, 7.5 mm, 10 mm, 12.5 mm, or 15 mm or less. In some embodiments, the flow velocity through the fluid container can be 0.1 mm / sec to 1000 mm / sec. In some embodiments, the flow velocity through the fluid container can be 0.05 mm / sec, 0.075 mm / sec, 0.1 mm / sec, 0.3 mm / sec, or 0.5 mm / sec or more. In some embodiments, the flow velocity through the fluid container can be 500 mm / sec, 750 mm / sec, 1000 mm / sec, 1250 mm / sec, or 1500 mm / sec or less.

[0062] In some embodiments, the fluidic channel / reservoir etching step may include dry etching such as reactive ion etching, deep reactive ion etching, and / or neutral loop discharge etching, and in some embodiments may include wet etching such as etching with buffered hydrofluoric acid. In some embodiments, the etching process may also include etching regions at the ends of the solid core waveguides, thereby forming ends of the optical waveguides (e.g., optical facets) through which light can be coupled out.

[0063] After forming the waveguide layer to include optical waveguides and after etching the waveguide layer to form fluid channels and / or fluid reservoirs, a cover layer can be applied to the top surface of at least a portion of the waveguide layer to surround the open sides of the fluid channels / reservoirs. In some embodiments, the cover layer can completely cover the waveguide layer and / or waveguide cores. In some embodiments, the cover layer can be bonded to a uniform surface of the waveguide layer, and the cover layer can be bonded onto the uniform surface of the waveguide layer without having to avoid or surround air gaps etched in the waveguide layer. For example, the cover layer can be applied to a uniform upper surface (e.g., top surface) of a waveguide layer that includes waveguides, including waveguide cores. Bonding a cover layer to a waveguide layer that is formed without air gaps can be advantageous because it increases the bonding area (thereby increasing bonding strength), simplifies the bonding process, and avoids the need to prevent adhesives or other foreign matter from being trapped in the air gaps.

[0064] In some embodiments, the cover layer can be affixed to the waveguide structure at least where the waveguide layer intersects the fluidic channel / reservoir. In some embodiments, the cover layer can include a recessed portion (e.g., disposed at least adjacent to or above the fluidic channel / reservoir) such that the height of the fluidic channel / reservoir can extend into a portion of the thickness of the cover layer. In some embodiments, the cover layer can include a polymer, a silicone (e.g., polydimethylsiloxane (PDMS)), a pressure-sensitive adhesive layer, bonded glass, an ARROW layer, a totally reflective coated (e.g., a low refractive index material such as TEFRON AF), or a metal coated material. In some embodiments, the cover layer can be 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 150 μm, or 200 μm, 300 μm, 1 mm, 5 mm, or 10 mm thick or less. In some embodiments, the cover layer can be 1 μm, 5 μm, or 10 μm, 50 μm, 100 μm, 150 μm, or 200 μm, 300 μm, 1 mm, 5 mm, or 10 mm or more thick. In some embodiments, the cover layer can be affixed to the waveguide layer by permanent or non-permanent bonding, adhesive gluing, suction, adhesive tape, laser bonding, or other suitable means. For example, the top surface of the waveguide structure can be flat to allow for bonding and / or sealing of fluidic channels / reservoirs via PDMS.

[0065] After etching and bonding of the cover layer is complete, the fluidic channel and / or reservoir can be filled with a fluid, such as a gas or liquid, containing the analyte, to propagate along the solid core waveguide and be excited by excitation light incident on the fluidic channel. In some embodiments, the emission light from the analyte in the fluidic channel (or reservoir) can be collected out-of-plane (e.g., by photodetection from above or below) or in-plane (e.g., by being directed by the fluidic channel to an in-plane photodetector if the fluidic channel is a fluidic core waveguide, or by the emission light being captured by a solid core waveguide structure without a fluidic core waveguide).

[0066] In some embodiments, the performance of the fluid channel as a fluid core waveguide (e.g., for in-plane detection of emitted light) can be increased by reducing the average refractive index of the cladding material or by etching away some of the substrate layer below the channel, as discussed further below.

[0067] 1A-1E show schematic diagrams of a waveguide structure 100 according to some embodiments. FIG. 1A shows cross-sectional views of the waveguide structure 100 from two angles, divided into two perspectives by a vertical line 102 indicating a 90° corner. FIG. 1B shows an overhead view of a portion of the waveguide structure 100. FIG. 1C-1E show additional waveguide architectures 104 for guiding light using optofluidic chips or devices.

[0068] 1A , the waveguide layer 106 can be formed by one or more oxide layers. In some embodiments, a low-index oxide layer 108 can be disposed on a substrate (e.g., silicon) layer 116, a high-index oxide layer 110 can be disposed on the low-index oxide layer 108, and an additional low-index oxide layer 112 can be disposed on the high-index layer 110. In some embodiments, a high-index oxide strip 114 can be disposed on the high-index layer 110 such that the high-index oxide strip 114 protrudes into at least a portion of the second low-index layer 112. In some embodiments, the high-index oxide strip 114 can be disposed below the high-index oxide layer 110 such that the strip 114 protrudes from the high-index oxide layer 110 into at least a portion of the first low-index layer 108. In some embodiments, the high-index oxide strip 114 is disposed both above and below the high-index oxide layer 110 such that the strip protrudes into each of the low-index oxide layers 108 and 112. The three oxide layers and at least one high-index oxide strip 114 can collectively form the waveguide layer 106. Light 128 propagates primarily within the high-index oxide layer 110 and / or high-index oxide strip 114 and may be internally reflected at interfaces with the low-index oxide layers 108 and / or 112. Thus, a ridge waveguide can be provided in the high-index oxide layer 110 and / or high-index oxide strip 114, where the ridge waveguide core can support one or more modes of light propagating along the waveguide. For example, the ridge waveguide can include a core region and a cladding region for propagating light along the waveguide. In some embodiments, both the low-index oxide layer 108 and the substrate layer 116 can be replaced with a low-index substrate layer.

[0069] In some embodiments, the high index oxide strips 114 may have a refractive index equal to the refractive index of the high index oxide layer 110. In some embodiments, the refractive indices of the high index oxide strips 114 and the high index oxide layer 110 may be similar but not identical, for example, differing from one another by an amount equal to or less than 0.00001, 0.0001, 0.001, 0.01, 0.02, or 0.05. In some embodiments, the refractive indices of the high index oxide strips 114 and the high index oxide layer 110 may differ from one another by an amount equal to or less than 0.00001, or 0.0001, 0.001, 0.01, 0.02, or 0.05.

[0070] In some embodiments, the waveguide structure 100 may further include an aperture layer 118 adjacent (e.g., directly adjacent or indirectly adjacent) and / or coupled to the waveguide layer 106 and disposed on the substrate layer 116. The aperture layer 118 may include a non-transparent metal such as chromium, nickel, another metal, one or more anti-resonance reflective optical waveguide (ARROW) layers, and / or another opaque material configured to block background light. In some embodiments, one or more layers (e.g., a substrate layer, an oxide layer, etc.) may be disposed between the low-index oxide layer 108 and the substrate layer 116, and the aperture layer 118 may be disposed below one or more layers adjacent to the substrate layer 116. The aperture layer 118 may be configured to allow signal light to pass through the aperture 120 and be collected while blocking other light. In some embodiments, the aperture layer 118 can be micro-fabricated such that one or more features of the aperture itself can be formed using micro-fabrication (e.g., sputtering, e-beam evaporation, spin coating, and / or one or more coating techniques. In some embodiments, one or more apertures 120 can be created by focused ion beam and / or other subtractive manufacturing techniques.

[0071] In some embodiments, the apertures and / or aperture layers can be disposed in the cover layer 124, for example, such that the apertures can be aligned with the fluidic channels 122. In some embodiments, one or more apertures 120 formed in the aperture layer 118 can be positioned near the fluidic channels 122 and near lenses (described below) embedded in the substrate layer 116 to allow signal light from the fluidic channels 122 to pass through the aperture layer 118 and into and be focused by the lenses in the substrate layer 116, while blocking background light that does not pass through the apertures 120 but is instead blocked by opaque portions of the aperture layer 118. In some embodiments, the one or more apertures 120 can be aligned with the centers of the fluidic channels 122. In some embodiments, the one or more apertures 120 are aligned with the fluidic channels 122, but need not be aligned with the centers of the fluidic channels 122. In some embodiments, the one or more apertures can span the entire width of the channels 122. In some embodiments, aperture 120 can span less than the entire width of channel 122. In some embodiments, aperture 120 can span 5%, 10%, 25%, 40%, 50%, 60%, 75%, 90%, or 95% or more of the width of channel 122. In some embodiments, aperture 120 can span 5%, 10%, 25%, 40%, 50%, 60%, 75%, 90%, or 95% or less of the width of channel 122.

[0072] In some embodiments, the aperture layer 118 can include one or more adjacent apertures, apertures of different shapes, multiple apertures forming one or more patterns, and / or spectrally independent apertures (e.g., the aperture layer 118 can include a stack of ARROW layers in some embodiments). In some embodiments, the excitation light can be spatially filtered using one or more apertures 120 in the aperture layer 118, for example, such that a beam of excitation light incident on the waveguide structure 100 can pass only through one or more apertures 120 in the aperture layer 118.

[0073] In some embodiments, the substrate layer 116 can comprise a transparent (e.g., silicon, PDMS, a polymer, glass, etc.) or opaque material (e.g., chromium, nickel, another metal, one or more ARROW layers, etc.). In some embodiments, the substrate layer can comprise one or more backside etches 126. For example, in addition to the top-down etches performed to create the fluidic channels and / or reservoirs, a bottom-up etch can be performed to create a backside etch in the opaque substrate layer, which can facilitate, for example, out-of-plane collection of light emitted from the fluidic channels 122, where the light can be collected below the structure 100. In embodiments using one or more backside etches 126, an additional oxide sealing layer (not shown) may be required. For example, the additional oxide sealing layer can be an optically transparent material having a low refractive index. In some embodiments, the additional sealing layer can be disposed on the substrate layer 116 before the aperture layer 118. In some embodiments, the additional sealing layer can be disposed on the aperture 118 before the oxide layer of the waveguide layer 106. In some embodiments, additional oxide sealing layers may be disposed both above and below the aperture 118, for example, to optically isolate the aperture layer and prevent the aperture layer from absorbing light exiting the light guide. Additionally, by physically isolating the aperture layer 118, etching and / or other post-processing steps may be performed on one or more of the substrate layer 116 and / or the waveguide layer 106 without disturbing the aperture layer 118 and / or the aperture 120.

[0074] In some embodiments, etching into the substrate layer 116, such as by etching into the side of the substrate layer 116 opposite the waveguide layer 106 as shown in FIG. 1A , can additionally or alternatively be used to form structures on the waveguide structure 100 for use in physically positioning the waveguide structure 100. In some embodiments, micromachining of the substrate 116 can be used to form one or more kinematic structures. In some embodiments, one or more structures etched into the substrate layer 116 can be used to bond to and / or physically interact with a physical positioning and / or alignment system. In some embodiments, one or more structures etched into the substrate layer 116 can be filled with, receive, and / or otherwise bonded to a magnetic material and / or one or more magnetic components for use in kinematic applications.

[0075] In some embodiments, the waveguide structure 100 using the backside etch 126 can include a lens (not shown), which can be configured to be positioned in the etch 126. The lens can be bonded below the fluidic channel 122 following bottom-up etching of the substrate layer 116 for bottom-side collection of the excitation light 128 from the fluidic channel 122. In some embodiments, the lens can be formed from a polymeric material, a dielectric material, glass, or any other suitable material.

[0076] As shown in FIG. 1A , the etching step that forms the fluid channel 122 can be performed such that the high-index oxide layer 110, the low-index oxide layer 108, the low-index oxide layer 112, and the oxide strip 114 are etched simultaneously (e.g., as part of a single etching step). That is, rather than separately etching the oxide layers and then aligning the air gaps / channels etched therein, the etching can be performed after the layers are already bonded to each other, thereby achieving self-alignment. As shown in the example of FIG. 1A , in some embodiments, the channel 122 can be formed by etching completely from above through the high-index oxide layer 110, the low-index oxide layer 112, the low-index oxide layer 108, and / or the oxide strip 114. In some embodiments, the aperture layer 118 can be etched from above to form apertures 120 below the fluid channel 122.

[0077] In addition to the etching steps that may be required to form the fluidic channels 122, in some embodiments, the waveguide structures can be fabricated by using one or more additional lithography steps to define the waveguide strips 114. In some embodiments, because there may be only two lithography steps, it may be simple to apply this method to create more complex waveguide structures and expose individual dies to this process (e.g., e-beam defined features). Furthermore, there may be no need to align masks between fabrication steps in this workflow.

[0078] In some embodiments, the waveguide structure 100 can include a cover layer 124, which can be applied to a portion of the top surface of the waveguide layer 106 to encapsulate the open sides of the fluid channels 122. In some embodiments, the cover layer 124 can extend the length of the waveguide structure 100 above the waveguide layer 106. In some embodiments, the cover layer 124 can extend over areas adjacent to all or a portion of the ridge waveguides of the structure 100 (e.g., vertically aligned as shown in FIG. 1A ). In some embodiments, the cover layer 124 can extend over areas adjacent to all or a portion of the oxide strips 114 (e.g., vertically aligned as shown in FIG. 1A ).

[0079] In some embodiments of any of the waveguide structures disclosed herein, one or more of the oxide layers may be deposited on another of the oxide layer, aperture layer, oxide strip, other components of the waveguide layer, and / or substrate layer. In some embodiments of any of the waveguide structures disclosed herein, the orientation of one or more layers and / or other components of the waveguide structure may be varied. For example, those skilled in the art will understand that when describing a first oxide layer as being "over" a second oxide layer, the first oxide layer may additionally and / or alternatively be "below" the second oxide layer (e.g., two oxide layers may be adjacent to each other). Furthermore, those skilled in the art will understand that one or more additional oxide layers may be present between the first oxide layer adjacent to the second layer (e.g., a third oxide layer may be disposed between the first and second oxide layers). In some embodiments, the deposition may be via sputtering, spin-on, plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD), electron beam evaporation, and / or any other deposition method.

[0080] In some embodiments of the waveguide structure 100 and / or other waveguide structures discussed herein, the refractive index of the oxide layer (or strip, rib, etc.) can be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 or less. In some embodiments of FIG. 1A and other waveguide structures discussed herein, the refractive index of the oxide layer (or strip, rib, etc.) can be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 or more. In some embodiments, the difference in refractive index between adjacent high and low index oxide layers can be 0.0001, 0.001, 0.01, or 0.1 or less. In some embodiments, the difference in refractive index between adjacent high and low index oxide layers can be 0.0001, 0.001, 0.01, or 0.1 or more. In some embodiments, the refractive index of a high-index oxide layer can be greater than the refractive index of an adjacent low-index oxide layer by 0.01%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, or 10% or more of the refractive index of the adjacent low-index oxide layer. In some embodiments, the refractive index of a high-index oxide layer can be greater than the refractive index of an adjacent low-index oxide layer by 0.01%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, or 10% or less of the refractive index of the adjacent low-index oxide layer.

[0081] In some embodiments, the thickness of the first oxide layer (e.g., low-index oxide layer 108) adjacent to the substrate layer 116 and / or aperture layer 118 can be 0.05 μm, 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, or 50 μm or less. In some embodiments, the thickness of the first oxide layer (e.g., low-index oxide layer 108) adjacent to the substrate layer 116 and / or aperture layer 118 can be 0.05 μm, 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, or 50 μm or more. In some embodiments, a thicker oxide layer (e.g., low-index oxide layer 108) adjacent to the substrate layer 116 and / or substrate layer 118 can improve the guiding properties of the waveguide and / or reduce background photoluminescence from the adjacent silicon / substrate material.

[0082] In some embodiments, the presence of low index layers 108 and 112 (or alternatively ARROW layers) can create well-defined waveguides, and cover layer 124 can allow any type of material to be used to seal fluid channel 122 without significantly interfering with the optical properties required for waveguiding in solid core waveguide 106, and in some embodiments, fluid core waveguides.

[0083] In some embodiments, the thickness of the second (intermediate) oxide layer (e.g., high-refractive-index oxide layer 110) disposed on the first oxide layer can be 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, or 15 μm or less. In some embodiments, the thickness of the second (intermediate) oxide layer (e.g., high-refractive-index oxide layer 110) can be 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, or 15 μm or more.

[0084] In some embodiments, the thickness of the oxide strips (e.g., high refractive index oxide strips 114) disposed within the waveguide layer can be 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, 15 μm, or 30 μm or less. In some embodiments, the thickness of the oxide strips (e.g., high refractive index oxide strips 114) disposed within the waveguide layer can be 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, 15 μm, or 15 μm or more.

[0085] In some embodiments, the width of the oxide strips (e.g., high refractive index oxide strips 114) disposed within the waveguide layer can be 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 25 μm, or 50 μm or less. In some embodiments, the width of the oxide strips (e.g., high refractive index oxide strips 114) disposed within the waveguide layer can be 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 25 μm, or 50 μm or more.

[0086] In some embodiments, the thickness of the third (top) oxide layer (e.g., low refractive index oxide layer 112) disposed on the second oxide layer 110 and / or oxide strips 114 can be 0.1 μm, 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, 15 μm, or 30 μm or less. In some embodiments, the thickness of the third oxide layer (e.g., low refractive index oxide layer 112) disposed on the second oxide layer 110 and / or oxide strips 114 can be 0.1 μm, 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, 15 μm, or 30 μm or more.

[0087] In some embodiments, the thickness of the oxide strips 114 can be equal to or less than the thickness of the low index oxide layer 112, such that the oxide strips 114 extend through at least a portion of the low index layer 112 but do not exceed the thickness of the low oxide layer 112. For example, the thickness of the oxide strips 114 can extend through at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the low oxide layer 112. In some embodiments, the thickness of the oxide strips 114 can extend through no more than 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the low oxide layer 112.

[0088] 1C-1E illustrate additional waveguide architectures 104 for the waveguide structure 100. In particular, FIGS. 1C-1E illustrate cross-sectional views of the waveguide structure 100 in FIG. 1A, showing only the left side of the bounded 90° corner 102. Each of the waveguide structures in FIGS. 1C-1E can include any one or more of the features described with respect to FIGS. 1A-1B.

[0089] FIG. 1C illustrates a buried waveguide architecture according to some embodiments. As shown, the waveguide layer can be formed from one or more low-index oxide layers and high-index buried oxide strips. In some embodiments, the low-index oxide layer 132 can be disposed on the substrate layer 130. The high-index oxide strip 134 can be disposed (e.g., laid down or deposited) on the low-index layer 132. In some embodiments, a low-index oxide layer 136 can be present on both sides of the high-index oxide strip 134, and an additional low-index oxide layer 138 can be disposed on the high-index oxide strip 134 and / or the low-index oxide layer 136. In some embodiments, the low-index oxide layers 136 and 138 can be disposed substantially simultaneously, thereby surrounding the high-index oxide strip 134. The three oxide layers and the oxide strip 134 can together form a waveguide layer (e.g., waveguide layer 106 in FIG. 1A). Light (e.g., light 128 in FIG. 1A) propagates primarily through the high-index oxide strip 134 and may be internally reflected at interfaces with the low-index oxide layers 132, 136, and / or 138. For example, the buried waveguide may include core and cladding regions provided primarily in and / or surrounding the high-index oxide strip 134 for propagating light along the waveguide. The buried waveguide may provide one or more optical modes (e.g., standing modes, transverse modes, transverse electromagnetic modes, and / or fundamental transverse electromagnetic modes (TEM)) propagating along the waveguide. 00 In some embodiments, both the low refractive index oxide layer 132 and the substrate layer 130 can be replaced with a low refractive index oxide substrate layer.

[0090] The thickness of one or more of the oxide layers 132, 136, and / or 138 can be generally the same as that of the oxide layers 108, 110, and / or 112 described above with respect to FIG. 1A. In some embodiments, the thickness of the high refractive index oxide strip 134 can be 0.1 μm, 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, or 50 μm or less. In some embodiments, the thickness of the high refractive index oxide strip 134 can be 0.1 μm, 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, or 50 μm or more. In some embodiments, the thickness of the high refractive index oxide strip 134 can be less than or equal to the thickness of the low refractive index layer 136. In some embodiments, the thickness of the high refractive index oxide strip 134 can be greater than or equal to the thickness of the low refractive index layer 136.

[0091] In some embodiments, the width of the high refractive index oxide strip 134 can be substantially the same as that of the high refractive index oxide strip 114 described above with respect to FIG. 1A. In some embodiments, the width of the high refractive index oxide strip 134 can be 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 25 μm, or 50 μm or more. In some embodiments, the width of the high refractive index oxide strip 134 can be 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 25 μm, or 50 μm or less.

[0092] 1D illustrates a strip-loaded waveguide architecture 104 according to some embodiments. As shown, the waveguide layer may include a low-index oxide layer 142 disposed (e.g., laid down or deposited) on a substrate layer 140. A high-index oxide layer 144 may be disposed on the low-index oxide layer 142, and a low-index oxide strip 146 may be disposed on the high-index layer 144. In addition, a medium-index oxide layer 148 may be disposed on the low-index oxide strip 146 and / or the high-index oxide layer 144. The three oxide layers and the oxide strip 146 may together form a waveguide layer (e.g., waveguide layer 106 in FIG. 1A). Light (e.g., light 128 in FIG. 1A) propagates primarily through the high-index oxide layer 144 and may be internally reflected at interfaces with the low- and / or medium-index oxide layers 142, 148, and / or the oxide strip 146. In some embodiments, the refractive index difference between the low-index oxide strip 146, the high-index oxide layer 144, the low-index oxide layer 142, and the medium-index oxide layer 148 can be configured such that one or more modes of propagating light are confined to the region of the high-index oxide layer 144 located below the strip 146. Thus, the strip-loaded waveguide can primarily include core and cladding regions located in and / or surrounding the high-index oxide layer 144 below the oxide strip 146 to propagate light along the waveguide. The strip-loaded waveguide can support one or more optical modes propagating along the waveguide. In some embodiments, both the low-index oxide layer 142 and the substrate layer 140 can be replaced with a low-index oxide substrate layer.

[0093] The thickness of one or more oxide layers 142, 144, and / or 148 can be generally the same as oxide layers 108, 110, and / or 112 described above with respect to FIG. 1A. In some embodiments, the thickness of low-index oxide strips 146 can be 0.1 μm, 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, or 50 μm or less. In some embodiments, the thickness of low-index oxide strips 146 can be 0.1 μm, 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, or 50 μm or more. In some embodiments, low-index oxide strips 146 can protrude into at least a portion of medium-index layer 148. In some embodiments, the low index oxide strips 146 extend through more than 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the thickness of the medium index layer 148. In some embodiments, the low index oxide strips 146 extend through less than 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the thickness of the medium index layer 148.

[0094] In some embodiments, the width of the low refractive index oxide strips 146 can be 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 25 μm, or 50 μm or more. In some embodiments, the width of the low refractive index oxide strips 146 can be 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 25 μm, or 50 μm or less.

[0095] FIG. 1E illustrates a slot waveguide architecture 104 according to some embodiments. As shown, the waveguide layer may include a low-index oxide layer 152 disposed (e.g., laid or deposited) on a substrate (e.g., silicon) layer 150, followed by a high-index oxide layer 154 disposed on the low-index oxide layer 152. In some embodiments, at least two high-index oxide ribs 156 may be disposed on the high-index oxide layer 154, flanking the slot waveguide region with a second low-index oxide layer 158 disposed on the high-index oxide layer 154 and / or the high-index oxide ribs 156. The three oxide layers and the at least two oxide ribs 156 may together form a waveguide layer (e.g., waveguide layer 106 in FIG. 1A). As light (e.g., light 128 in FIG. 1A) propagates primarily through the slot waveguide region of the low-index oxide layer 158 located between the ribs 156, it may be internally reflected at interfaces with the ribs 156 and / or layer 154. In some embodiments, the refractive index difference between the low-index oxide layer 158, the high-index oxide layer 154, and the ribs 156 can be configured such that one or more optical propagation modes are constrained to slot waveguide regions in the low-index oxide layer 158 located between the ribs 156. Thus, a slot waveguide, including a waveguide core region and a cladding region, can be located primarily in and / or surrounding the low-index oxide layer 158 at locations between the ribs 156 above the oxide strip 154, and the slot waveguide can support one or more optical propagation modes along the waveguide. In some embodiments, both the low-index oxide layer 152 and the substrate layer 150 can be replaced with a low-index substrate layer.

[0096] The thickness of one or more oxide layers 152, 154, and / or 158 can be generally the same as oxide layers 108, 110, and / or 112 described above with respect to FIG. 1A. In some embodiments, the thickness of each oxide rib 156 can be 0.1 μm, 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, or 50 μm or less. In some embodiments, the thickness of each oxide rib 156 can be 0.1 μm, 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, or 50 μm or more. In some embodiments, at least two oxide ribs 156 can protrude into at least a portion of low refractive index oxide layer 158. In some embodiments, the pairs of oxide ribs 156 extend through more than 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the thickness of the low index layer 158. In some embodiments, the pairs of oxide ribs 156 extend through less than 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the thickness of the low index layer 158.

[0097] In some embodiments, the width of the slot waveguide region of the second low oxide layer 158 between the ribs 156 can be 50 nm, 100 nm, 250 nm, 500 nm, 750 nm, 1000 nm, or 1200 nm or more. In some embodiments, the width of the slot waveguide region of the second low oxide layer 158 between the ribs 156 can be 50 nm, 100 nm, 250 nm, 500 nm, 750 nm, 1000 nm, or 1200 nm or less.

[0098] In some embodiments, the width of any particular one of the oxide ribs 156 can be 50 nm, 100 nm, 250 nm, 500 nm, 1 μm, 5 μm, 10 μm, 15 μm, or 25 μm or more. In some embodiments, the width of any particular one of the oxide ribs 156 can be 50 nm, 100 nm, 250 nm, 500 nm, 1 μm, 5 μm, 10 μm, 15 μm, or 25 μm or less.

[0099] 2A-2B show schematic diagrams of a waveguide structure 200 according to some embodiments. FIG. 2A shows cross-sectional views of the waveguide structure 200 from two angles, divided into two perspectives by a dotted line indicating a 90° corner 202. FIG. 2B shows an overhead view of a portion of the waveguide structure 200. The waveguide structure 200 may include any of the features described above with respect to FIGS. 1A-1E, except that rather than intersecting a waveguide layer with fluid channels, the optofluidic device may comprise a free-flowing, open fluid reservoir 230. For example, the waveguide architecture 204 shown in FIG. 2A may optionally be replaced with any of the additional waveguide architectures 104 shown in FIGS. 1C-1E. For example, the waveguide architecture 204 can include multiple oxide layers (e.g., oxide layers 208, 210, 212) and an oxide strip 214 forming the waveguide layer 206, and the fluid enclosure 230 can intersect at least a portion of the oxide layers and oxide strips. The waveguide layer 206 can include a waveguide for guiding light toward the fluid enclosure 230, the waveguide including a core region, a cladding region, and a surrounding boundary region (e.g., wall).

[0100] In some embodiments, the fluid reservoir 230 can be 2, 3, 4, or 5 times larger or more than the fluid channel 122 described with respect to FIGS. 1A and 1B. In some embodiments, the fluid reservoir 230 can be 2, 3, 4, or 5 times larger or less than the fluid channel 122. For example, the height and / or width of the fluid reservoir can be between 100 μm and 10 mm. In some embodiments, the height and / or width of the fluid reservoir can be 100 μm, 500 μm, 1 mm, 5 mm, or 10 mm or less. In some embodiments, the height and / or width of the fluid reservoir can be 100 μm, 500 μm, 1 mm, 5 mm, or 10 mm or more.

[0101] In some embodiments, the fluid enclosure 230 can include an imaging region located proximate the aperture 220 and a non-imaging region located away from the aperture 220. In some embodiments, one or more sensors (not shown) can be configured to capture signals from analytes (e.g., particles) suspended in the imaging region of the channel when the analytes are illuminated and / or excited by light propagating through the waveguide layer. In some embodiments, the sensor (e.g., a photodetector) can be positioned on the aperture layer 218 opposite the enclosure 230. In this manner, image data from a particle can be detected only when the particle is in the imaging region adjacent the aperture 220, even if the particle emits light elsewhere in the fluid enclosure 230. In some embodiments, the sensor can be located outside the plane of the fluid enclosure 230 of the waveguide structure 200. In some embodiments, the sensor can be located separately from the waveguide structure 200. In some embodiments, the sensor can be provided as part of (i.e., physically attached to and / or integrated with) the waveguide structure 200.

[0102] In some embodiments, the waveguide structure 200 can include an agitation device, mixer, pump, stirrer, sonicator, and / or other mechanism (not shown) configured to generate turbulence and / or flow within the fluid container.

[0103] While this disclosure has discussed the use of certain oxide materials in the waveguide layers of waveguide structures, the waveguide layers of the structures disclosed herein, in some embodiments, can be formed (in whole or in part) from one or more alternative or additional materials, including, but not limited to, materials deposited using vapor deposition (e.g., oxides such as titanium dioxide deposited by plasma enhanced chemical vapor deposition (PECVD) or low pressure chemical vapor deposition (LPCVD)), materials formed by thermal oxidation (e.g., silicon dioxide formed from thermal oxidation of silicon), spin-on glass, any one or more other materials that can be selected or configured for background reduction, and / or one or more plastics (e.g., polydimethylsiloxane (PDMS), cyclic olefin copolymer (COC), cyclic olefin polymer (COP)).

[0104] In some embodiments, following fabrication of a waveguide structure by any one or more of the fabrication techniques disclosed herein, one or more additional processes can be performed to further modify the fabricated chip, including, but not limited to, deposition, chemical modification, altering the surface chemistry, and / or altering the topology. In some embodiments, these one or more additional processes can be used to modify and / or enhance one or more properties of the fabricated structure, such as its hydrophobicity, smoothness, and / or reactivity.

[0105] The foregoing description has been provided with reference to specific embodiments for purposes of explanation. However, the illustrative discussion above is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teachings. The embodiments were chosen and described in order to best explain the basic scheme of the technology and its practical application, thereby enabling those skilled in the art to best utilize the technology and various embodiments, with various modifications suited to the particular use contemplated. While features may be described herein as part of the same or separate embodiments for purposes of clarity and conciseness, it will be understood that the scope of the present disclosure includes embodiments having all or any combination of the described features.

[0106] Although the disclosure and examples have been fully described with reference to the accompanying drawings, it should be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of the disclosure and examples as defined by the claims. Finally, the entire disclosures of the patents and publications mentioned in this application are incorporated herein by reference.

Claims

1. a waveguide layer comprising: a first oxide layer; a second oxide layer adjacent to the first oxide layer; a third oxide layer adjacent to the second oxide layer on an opposite side of the first oxide layer; and an oxide strip adjacent to the second oxide layer and extending at least partially into the third oxide layer, wherein the first, second, and third oxide layers and oxide strip form a ridge waveguide; a fluidic channel extending through at least a portion of the first, second, and third oxide layers and the oxide strip and intersecting the ridge waveguide, such that light carried by the ridge waveguide is incident on the fluidic channel; a cover layer attached to the waveguide layer and surrounding the fluid channel; A waveguide structure comprising:

2. the second oxide layer and the oxide strip each have a first refractive index; The waveguide structure of claim 1 .

3. the first and third oxide layers each have a second refractive index lower than the first refractive index; The waveguide structure of claim 2 .

4. an aperture layer adjacent to the waveguide layer; The waveguide structure according to any one of claims 1 to 3.

5. the aperture layer comprises chromium, nickel, another metal, and / or one or more anti-resonance reflective optical waveguide (ARROW) layers; The waveguide structure of claim 4 .

6. the aperture layer is configured to allow light to pass through one or more apertures in the aperture layer; the one or more apertures are aligned with the fluid channel; The waveguide structure according to claim 4 or 5.

7. a substrate layer adjacent to the aperture layer and opposite the waveguide; The waveguide structure according to any one of claims 4 to 6.

8. the substrate layer comprises one or more materials selected from the group: silicon, silica, and glass; The waveguide structure of claim 7.

9. the substrate layer includes etched regions aligned with one or more apertures in the aperture layer; The waveguide structure according to claim 7 or 8.

10. the substrate layer includes an oxide sealing layer; The waveguide structure of claim 9.

11. the etched region includes a lens element configured to focus light leaking from the fluid channel into the etched region. The waveguide structure according to claim 9 or 10.

12. the cover layer is bonded to the waveguide layer at a location adjacent to the ridge waveguide; The waveguide structure according to any one of claims 1 to 11.

13. the cover layer includes one or more apertures aligned with the fluid channels; The waveguide structure according to any one of claims 1 to 12.

14. a waveguide layer comprising: a first oxide layer; a second oxide layer adjacent to the first oxide layer; a third oxide layer adjacent to the second oxide layer on an opposite side of the first oxide layer; and an oxide strip disposed within the second oxide layer, wherein the first, second, and third oxide layers and the oxide strip form a buried waveguide; a fluidic channel extending through at least a portion of the first, second, and third oxide layers and the oxide strip and intersecting the buried waveguide, such that light carried by the buried waveguide is incident on the fluidic channel; a cover layer attached to the waveguide layer and surrounding the fluid channel; A waveguide structure comprising:

15. the first, second, and third oxide layers each have a first refractive index; 15. The waveguide structure of claim 14.

16. the oxide strip has a second refractive index higher than the first refractive index; 16. The waveguide structure of claim 15.

17. the cover layer is bonded to the waveguide layer at a location adjacent to the buried waveguide; The waveguide structure according to any one of claims 14 to 16.

18. a waveguide layer comprising: a first oxide layer; a second oxide layer adjacent to the first oxide layer; a third oxide layer adjacent to the second oxide layer on an opposite side of the first oxide layer; and an oxide strip adjacent to the second oxide layer and extending at least partially into the third oxide layer, wherein the first, second, and third oxide layers and the oxide strip form a strip-loaded waveguide; a fluidic channel extending through at least a portion of the first, second, and third oxide layers and through the oxide strip and intersecting the strip-loaded waveguide, such that light carried by the strip-loaded waveguide is incident on the fluidic channel; a cover layer attached to the waveguide layer and surrounding the fluid channel; A waveguide structure comprising:

19. the first oxide layer and the oxide strip each have a first refractive index; 20. The waveguide structure of claim 18.

20. the second oxide layer has a second refractive index higher than the first refractive index; 20. The waveguide structure of claim 19.

21. the third oxide layer has a third refractive index higher than the first refractive index and lower than the second refractive index; 21. A waveguide structure according to claim 19 or 20.

22. the first oxide has a first refractive index; The waveguide structure according to any one of claims 18 to 21.

23. the oxide strip has a second refractive index different from the first refractive index; 23. The waveguide structure of claim 22.

24. the cover layer is affixed to the waveguide layer at a location adjacent to the strip-loaded waveguide; The waveguide structure according to any one of claims 18 to 23.

25. a waveguide layer comprising: a first oxide layer; a second oxide layer adjacent to the first oxide layer; a third oxide layer adjacent to the second oxide layer on an opposite side of the first oxide layer; and at least two oxide ribs disposed adjacent to the second oxide layer and extending at least partially into the third oxide layer, wherein the first, second, and third oxide layers and the at least two oxide ribs form a slot waveguide between the at least two oxide ribs; a fluid channel extending through at least a portion of the first, second, and third oxide layers and the at least two oxide ribs and intersecting the slot waveguide, such that light carried by the slot waveguide is incident on the fluid channel; a cover layer attached to the waveguide layer and surrounding the fluid channel; A waveguide structure comprising:

26. the first and third oxide layers each have a first refractive index; 26. The waveguide structure of claim 25.

27. the second oxide layer and the at least two oxide ribs each have a second refractive index higher than the first refractive index; 27. The waveguide structure of claim 26.

28. the cover layer is bonded to the waveguide layer at a location adjacent to the slot waveguide; The waveguide structure according to any one of claims 25 to 27.

29. a waveguide layer including a waveguide; a fluid enclosure extending through at least a portion of the waveguide layer and intersecting the waveguide, such that light carried by the waveguide is incident on the fluid enclosure, the fluid enclosure including an imaging region and a non-imaging region; A waveguide structure comprising:

30. an aperture layer adjacent to the waveguide layer; the aperture layer includes a light blocking region disposed adjacent to the non-imaging region in the fluid enclosure, and includes one or more apertures disposed adjacent to the imaging region in the fluid enclosure.

30. The waveguide structure of claim 29.

31. the waveguide layer includes a plurality of oxide layers; 31. A waveguide structure according to claim 29 or 30.

32. the fluid enclosure extends through at least a portion of one or more of the oxide layers of the waveguide layer.

32. The waveguide structure of claim 31.

33. at least one device configured to generate turbulence in the fluid container to induce flow between the non-imaging region and the imaging region, the device being selected from the following set: an agitation device, an agitator, a mixer, a pump, and an ultrasonic disrupter; The waveguide structure according to any one of claims 29 to 32.

34. a substrate layer on the opposite side of the aperture layer from the waveguide layer; The waveguide structure according to any one of claims 29 to 33.

35. a sensor configured to capture image data of particles suspended within the imaging region of the vessel when the particles are illuminated or excited by light carried by the waveguide. A waveguide structure according to any one of claims 29 to 34.

36. an oxide strip disposed within the waveguide layer; the oxide strip has a first refractive index; The waveguide structure according to any one of claims 29 to 35.

37. At least a portion of the waveguide layer has a second refractive index different from the first refractive index.

37. The waveguide structure of claim 36.

38. the fluid reservoir extends through at least a portion of the oxide strip disposed within the waveguide layer; 38. A waveguide structure according to claim 36 or 37.

39. at least two oxide ribs disposed within the waveguide layer; the at least two oxide ribs have a first refractive index; A waveguide structure according to any one of claims 29 to 38.

40. At least a portion of the waveguide layer has a second refractive index different from the first refractive index.

40. The waveguide structure of claim 39.

41. the fluid reservoir extends through at least a portion of at least two of the oxide ribs disposed in the waveguide layer.

41. A waveguide structure according to claim 39 or 40.

42. 1. A method of manufacturing a waveguide structure, comprising: disposing a waveguide layer adjacent to a substrate layer, the waveguide layer including one or more oxide layers forming a waveguide, the waveguide layer having a planar upper surface; etching a fluid channel in the waveguide layer by etching through a portion of the planar top surface of the waveguide layer, the fluid channel intersecting at least one of the one or more oxide layers of the waveguide layer; disposing a cover layer adjacent to the waveguide layer, the cover layer covering the etched fluidic channels and being affixed to the waveguide layer at a location adjacent to the waveguide; A method comprising:

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