Optical structure

Abstract

An optical structure includes a grating coupler and a microlens. The grating coupler is configured to receive a laser. The microlens is positioned above the grating coupler, wherein a metal shield covers the microlens, the metal shield having an opening to allow the laser to enter an active coupling region of the grating coupler. The present disclosure provides various grating structures that have a greater active coupling angle and high coupling efficiency features that allow for the possibility of coupling more energy from a large laser beam and / or coupling multiple wavelengths into a grating waveguide to excite fluorescently labeled biomolecules. The present disclosure can also provide large alignment tolerances in the optical structure, thereby improving the overall coupling efficiency of the optical structure for biological detection.

Description

Technical Field

[0001] This invention relates to an optical structure, and more particularly to an optical structure applicable to biosensors. Background Technology

[0002] Grating waveguides are widely used in biosensors, augmented reality (AR), virtual reality (VR), and electronic communications. In the field of biosensors, grating coupling efficiency affects the luminescence efficiency of fluorescently labeled biomolecules, and several factors influence grating coupling efficiency. These include, for example, the alignment between external light and the grating structure, the material properties of the optical elements in the grating waveguide structure, and the geometry of the grating coupler.

[0003] External light can be coupled into an optical structure via a grating nanostructure to generate light propagating in a waveguide layer, which is used to uniformly and locally excite fluorescently labeled biomolecules within an evanescence region on the waveguide core. However, the coupling efficiency from the laser beam to the grating waveguide is relatively low due to stringent alignment requirements (including xyz axis offset and incident angle) and the relatively small effective coupling width of the grating coupler (compared to the diameter of the laser beam), resulting in low luminescence efficiency of the fluorescent label. Therefore, to improve the luminescence efficiency of fluorescently labeled biomolecules in biosensor applications, it is necessary to address the issue of grating coupling efficiency in the grating waveguide. Summary of the Invention

[0004] One aspect of this invention is to provide an optical structure. The optical structure includes a grating coupler and a microlens. The grating coupler is configured to receive laser light. The microlens is located above the grating coupler, wherein a metal shield covers the microlens, the metal shield having openings to allow laser light to enter the effective coupling region of the grating coupler.

[0005] According to some embodiments of the present invention, the opening of the metal shield is configured to allow a portion of the laser light to enter the microlens, and the opening has an angle range of -50 degrees to 50 degrees.

[0006] According to some embodiments of the present invention, due to the misalignment of the optical system, the laser has an offset angle, and the laser irradiation area is larger than the effective coupling area of ​​the grating coupler.

[0007] According to some embodiments of the present invention, the offset angle is in the range of -20 degrees to 20 degrees.

[0008] According to some embodiments of the present invention, a metal shield is disposed between the microlens and the grating coupler.

[0009] According to some embodiments of the present invention, the optical structure further includes a core layer, a substrate, and a top cover layer. The core layer is adjacent to the grating coupler. The substrate is covered by the core layer. The top cover layer covers the core layer.

[0010] According to some embodiments of the present invention, the substrate comprises sapphire or glass, and the refractive index of the substrate is in the range of 1.45 to 2.0.

[0011] According to some embodiments of the present invention, the substrate comprises silicon or complementary metal-oxide-semiconductor.

[0012] According to some embodiments of the present invention, the optical structure further includes an undercoat layer located between the substrate and the core layer, wherein the refractive index of the undercoat layer at visible wavelengths is less than 1.6 and the dielectric constant of the undercoat layer is less than 0.00001.

[0013] According to some embodiments of the present invention, the topcoat layer comprises silicon oxide or a polymer, and the refractive index of the core layer is greater than that of the topcoat layer.

[0014] According to some embodiments of the present invention, the refractive index of the overcoat at visible light wavelength is less than 1.6 and the dielectric constant of the overcoat is less than 0.00001.

[0015] According to some embodiments of the present invention, the grating coupler is embedded in the core layer.

[0016] According to some embodiments of the present invention, the grating coupler has a linear shape when viewed from above, the microlens has a semi-cylindrical cross-sectional shape, and the core layer includes a planar waveguide.

[0017] According to some embodiments of the present invention, the grating coupler has a curved shape when viewed from above, and the core layer contains multiple channel waveguides.

[0018] According to some embodiments of the present invention, the grating coupler has a surface facing the substrate and a sidewall adjacent to the surface, and the optical structure further includes a metal reflector disposed on the surface and sidewall of the grating coupler.

[0019] According to some embodiments of the present invention, a grating coupler is disposed on the surface of the core layer facing the microlens, a portion of the core layer is located between the grating coupler and the substrate, wherein the material of the grating coupler is different from the material of the core layer.

[0020] According to some embodiments of the present invention, the grating coupler has a tapered thickness.

[0021] According to some embodiments of the present invention, a grating coupler is disposed on the substrate-facing surface of the core layer, and a portion of the core layer is located between the microlens and the grating coupler.

[0022] According to some embodiments of the present invention, the optical structure further includes a metal reflector disposed on the surface of the grating coupler facing the substrate.

[0023] According to some embodiments of the present invention, the grating coupler is a stepped grating structure, a blazed grating structure, or a tilted grating structure.

[0024] According to some embodiments of the present invention, the stepped grating structure includes a first vertical sidewall, a second vertical sidewall, and a horizontal surface adjacent to the first vertical sidewall and the second vertical sidewall.

[0025] According to some embodiments of the present invention, the blazed grating structure includes inclined sidewalls extending from the top to the bottom of the blazed grating structure, and the width of the blazed grating structure gradually increases from the top to the bottom of the blazed grating structure.

[0026] According to some embodiments of the present invention, the tilted grating structure includes a first tilted sidewall, a second tilted sidewall, and a top surface adjacent to the first tilted sidewall and the second tilted sidewall. Attached Figure Description

[0027] The nature of this invention will be fully understood when read in conjunction with the accompanying drawings. It should be noted that, according to industry standard practice, the features are not drawn to scale and are for illustrative purposes only. In fact, the dimensions of the features may be increased or decreased arbitrarily for clarity of explanation.

[0028] Figure 1A , Figure 2 and Figure 3 This is a cross-sectional view of an optical structure according to some embodiments of the present invention.

[0029] Figure 1B for Figure 1A A magnified view of a portion of the grating coupler.

[0030] Figure 4 , Figure 5 , Figure 6 and Figure 7 This is a cross-sectional view of an optical structure according to some alternative embodiments of the present invention.

[0031] Figure 8 , Figure 9A , Figure 10A and Figure 11A This is a cross-sectional view of an optical structure according to some alternative embodiments of the present invention.

[0032] Figure 9B , Figure 10B and Figure 11B They are respectively Figure 9A , Figure 10A and Figure 11A A magnified view of a portion of the grating coupler.

[0033] Figure 12 , Figure 13 , Figure 14 and Figure 15 This is a cross-sectional view of an optical structure according to some alternative embodiments of the present invention.

[0034] Figure 16 This is a cross-sectional view of an optical structure according to some alternative embodiments of the present invention.

[0035] Figure 17A for Figure 16 A top view of the metal shielding of the optical structure in the image.

[0036] Figure 17B for Figure 16 A top view of the substrate, core layer, and grating coupler of the optical structure in the image.

[0037] Figure 17C For along Figure 17B A cross-sectional view of the substrate, core layer, and grating coupler along line A-A'.

[0038] Figure 18A for Figure 16 A top view of the metal shielding of the optical structure in the image.

[0039] Figure 18B for Figure 16 A top view of the substrate, core layer, and grating coupler of the optical structure in the image.

[0040] Figure 18C For along Figure 18B A cross-sectional view of the substrate, core layer, and grating coupler of line B-B'.

[0041] Figure 19 and Figure 20 for Figure 16 A top view of the substrate, core layer, and grating coupler of the optical structure in the image.

[0042] Figure 21A , Figure 21B , Figure 21C and Figure 21D For along Figure 19 The cross-sectional view along line C-C' and along Figure 20 A cross-sectional view of line D-D'.

[0043] Figure 22A , Figure 22B , Figure 22C , Figure 22D , Figure 22E and Figure 22F This is a cross-sectional view of various grating structures of grating couplers according to some embodiments of the present invention.

[0044] Figure 23A , Figure 23B , Figure 24A , Figure 24B , Figure 25A , Figure 25B , Figure 26A and Figure 26B To illustrate the intensity of green light with a wavelength of 532 nm under different grating structures according to some embodiments of the present invention, the incident angle of the light is plotted against the intensity.

[0045] The symbols in the attached diagram are briefly explained as follows:

[0046] 100, 100a, 100b, 100c, 100d: Optical structure; 110: Substrate; 120: Core layer; 122, 124: Surface; 130: Grating coupler; 130a: Stepped grating structure; 130b: Blazed grating structure; 130c, 130d, 130e, 130f: Tilted grating structure; 132: Top surface; 134: Bottom surface; 136, 138, 139: Sidewalls; 140: Top cover layer; 150: Microlens; 160, 160a: Laser; 164, 164a, 164b, 164c: Optical area; 170, 170a, 170b, 170c: Metal shield; 172 172a, 172b, 172c: Openings; 200: Optical structure; 210: Undercoat; 221, 222: Vertical sidewalls; 223: Horizontal surface; 224, 225, 226: Sloping sidewalls; 227: Top surface; 300: Optical structure; 710: Air gap; 800, 800a, 800b, 800c: Optical structure; 1200, 1200a, 1200b, 1200c: Optical structure; 1010: Metal reflector; 1600: Optical structure; p: Grating period; h: Height; D: Diameter; EB, EBa: Effective beam; F, F': Lens focal length; P, P': Focal point; T: Thickness; R eff : Effective coupling area; Wt: Top width; Wb: Bottom width; A-A', B-B', C-C', D-D': Lines; θ, θ', -θ: Angles; Δθ: Offset angle. Detailed Implementation

[0047] The following invention provides many different implementations or embodiments for achieving different features of the invention. Specific embodiments of components and arrangements are described below to simplify the invention. These are, of course, merely embodiments and are not intended to be limiting. For example, in the following description, the formation of a first feature above or on a second feature may include an embodiment where the first and second features are formed in direct contact, or an embodiment where another feature may be formed between the first and second features so that the first and second features are not in direct contact. Furthermore, reference numerals or words may be repeated in different embodiments. The purpose of repetition is to simplify and clarify the description, not to define the relationship between the different embodiments and configurations discussed. It should be understood that the number of any element / component is for illustration only and is not intended to limit the invention.

[0048] It will be understood that although terms such as “first,” “second,” etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of the embodiments, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0049] In addition, spatial relative terms such as "below," "below," "lower than," "above," and other similar terms are used here for the convenience of describing the relationship between one element or feature and another element or feature in the figure. Besides covering the orientation depicted in the figure, spatial relative terms also cover other orientations of the device during use or operation. That is, when the orientation of the device differs from that in the figure (rotated 90 degrees or in other orientations), the spatial relative terms used in this invention can still be interpreted accordingly.

[0050] In the field of biosensors, the luminescence efficiency of fluorescently labeled biomolecules is affected by the grating coupling efficiency. When external light containing one or more wavelengths enters an optical structure through a binary (second-order) grating coupler (GC), only light exposed at a precise incident angle (approximately + / - 1 degree) within the effective coupling region (about 10-20 μm near the inner edge of the grating coupler) can be coupled into the waveguide. Therefore, the grating coupling efficiency of optical structures is typically low. Grating coupling efficiency is influenced by factors such as the alignment between the external light and the grating structure, the laser beam diameter, the material properties of the optical elements within the grating waveguide structure, and the geometry of the grating coupler, among others.

[0051] The optical structure of this invention incorporates a microlens structure that converts a large, collimated laser beam into convergent, focused light exposed over an effective coupling region. This invention provides various grating structures, such as n-order (n>=3) gratings, blazed gratings, or slanted gratings, which feature greater angle tolerance and high grating coupling efficiency, allowing single or multiple wavelengths to be coupled into a grating waveguide to excite fluorescently labeled biomolecules. Specifically, when only a single wavelength is coupled into a grating waveguide, it may result in a reduction in the types of fluorophores that can be excited and emit fluorescent signals. In contrast, when multiple wavelengths are coupled into a grating waveguide, it may result in a greater variety of fluorophores being excited and emitting fluorescent signals. However, this invention is not limited to coupling single or multiple wavelengths. This invention can also provide larger alignment tolerances (including x, y, z axes and incident angle) in the optical structure, thereby improving the overall coupling efficiency of the optical structure for biological detection.

[0052] Figure 1A This is a cross-sectional view of an optical structure 100 according to some embodiments of the present invention. The optical structure 100 includes a substrate 110, a core layer 120, and a grating coupler 130. The substrate 110 is covered by the core layer 120. In some embodiments, the substrate 110 is a transparent substrate and comprises sapphire or glass. When the substrate 110 is a transparent substrate, the refractive index of the substrate 110 is in the range of 1.45 to 1.7, such as 1.5 or 1.6. The core layer 120 covers the substrate 110. In some embodiments, the refractive index of the core layer 120 is relatively higher than that of the substrate 110. In some embodiments, the core layer 120 comprises Nb₂O₅, Ta₂O₅, TiO₂, Si₃N₄, or other suitable materials. The grating coupler 130 is adjacent to the core layer 120 and configured to receive laser light 160. For example, the grating coupler 130 is embedded in the core layer 120. In some embodiments, the thickness of the core layer 120 is between about 0.05 μm and 0.5 μm, or thicker. Specifically, it is between 0.08 μm and 0.25 μm. In some embodiments, the grating coupler 130 is made of the same material as the core layer 120. In some embodiments, the grating coupler 130 is made of a different material than the core layer 120.

[0053] Please refer to Figure 1B . Figure 1B draw Figure 1AA partial enlarged view of the grating coupler 130 is shown. The grating coupler 130 has a plurality of protrusions and a plurality of recesses. The protrusions of the grating coupler 130 have a height h from the top surface 132 of the protrusion to the bottom surface 134 of the recess. The grating coupler 130 has a grating period p between two adjacent protrusions. The grating coupler 130 has a continuous surface comprising a top surface 132, a sidewall 136, a bottom surface 134, and a sidewall 138, and the continuous surface is located away from the substrate 110 of the optical structure 100. In some embodiments, the grating coupler 130 includes a stepped grating structure, a blazed grating structure, or a tilted grating structure. It should be understood that... Figure 1B The grating coupler 130 shown is for illustrative purposes only; its detailed structure will be described below. Figures 22A to 22F As described in the text.

[0054] Please refer to this again. Figure 1A The optical structure 100 includes a capping layer 140, a microlens 150, a laser 160, and a metal shield 170. The capping layer 140 covers the core layer 120. Specifically, the capping layer 140 extends and covers the surface of the core layer 120 and the surface of the grating coupler 130. In some embodiments, the capping layer 140 comprises silicon oxide or a polymer, and the refractive index of the core layer 120 is greater than the refractive index of the capping layer 140. In some embodiments, the refractive index of the capping layer 140 is less than 1.6, such as 1.1, 1.2, 1.3, 1.4, or 1.5. In some embodiments, the dielectric constant of the capping layer 140 at visible light wavelengths is less than 0.00001, such as 0.000008, 0.000005, or 0.000003. Microlens 150 is located above the overlay 140 and is configured to change the incident angle of one or more wavelengths of the laser 160 entering the grating coupler 130. Figure 1AIn the diagram, three arrows pointing to microlens 150 indicate the direction of travel of laser 160. Specifically, when laser 160 enters microlens 150, its direction of travel is changed. In some embodiments, the diameter D of microlens 150 is in the range of 0.05 mm to 50 mm, such as 0.2, 0.5, 1, 5, 10, 15, 20, 25, 30, 35, 40, or 45 mm. In some embodiments, the refractive index of microlens 150 is the same as or similar to the refractive index of overlay 140. Laser 160 is external light. In some embodiments, the laser beam of laser 160 has a diameter in the range of 0.1 mm to 10 mm, such as 0.2, 0.5, 1, 2, 4, 6, or 8 mm. Metal shield 170 covers microlens 150. Metal shield 170 has an opening 172 configured to allow a portion of laser 160 to enter microlens 150. The opening 172 of the metal shield 170 allows the laser 160 to enter the effective coupling region R of the grating coupler 130. eff In other words, the effective beam EB enters the microlens 150. The diameter of the effective beam EB is smaller than the diameter of the laser beam of the laser 160.

[0055] Figure 2 This is a cross-sectional view of an optical structure 200 according to some embodiments of the present invention. Compared to Figure 1A The optical structure 100 in the middle, Figure 2 The optical structure 200 further includes an undercoat layer 210. The undercoat layer 210 is located between the substrate 110 and the core layer 120. In some embodiments, the undercoat layer 210 comprises silicon oxide or a polymer, and the refractive index of the core layer 120 is greater than the refractive index of the undercoat layer 210. In some embodiments, the refractive index of the undercoat layer 210 is less than 1.6, such as 1.1, 1.2, 1.3, 1.4, or 1.5. In some embodiments, the undercoat layer 210 has a dielectric constant less than 0.00001 at visible wavelengths, such as 0.000008, 0.000005, or 0.000003. In some embodiments, the microlens 150 has the same or similar refractive index as the undercoat layer 210. In some embodiments, the substrate 110 is an opaque substrate and comprises a silicon wafer or a complementary metal oxide semiconductor (CMOS). In some embodiments, the substrate 110 is a transparent substrate and has a refractive index in the range of 1.45 to 2.0, such as 1.5, 1.6, 1.7, 1.8, or 1.9. When the substrate 110 is a transparent or opaque substrate and has a refractive index greater than 1.7, the undercoating layer 210 is disposed between the substrate 110 and the core layer 120.

[0056] Please refer to this again. Figure 1ATwo dashed lines, drawn from microlens 150 to grating coupler 130, form an optical region 164. Optical region 164 is an area that allows laser 160 to couple to grating coupler 130. The length of each dashed line has the lens focal length F, and the two dashed lines form an angle θ and a focal point P. In some embodiments, the angle θ is between 0 and 50 degrees, such as 5, 10, 20, 30, or 40 degrees. Figure 1A The focal point P of the optical structure 100 is located in the grating coupler 130. After the laser 160 is coupled into the grating coupler 130 through the microlens 150 and the overlying layer 140, the laser 160 propagates in the core layer 120, causing the fluorescently labeled biomolecules above the core layer 120 to emit light. The grating coupler 130 has an effective coupling region R of less than approximately 20 μm. eff Effective coupling region R eff This is a region where laser 160 can be coupled and transmitted within the core layer 120. In other words, if the light region 164 is focused and exposed to the effective coupling region R... eff If the incident angle is within the effective coupling angle of the grating coupler 130, then the laser 160 will be coupled and transmitted in the core layer 120. However, if the optical region 164 is within the effective coupling region R... eff If the laser 160 is outside the effective coupling angle of the grating coupler 130, it will not couple and propagate in the core layer 120.

[0057] Please refer to Figure 3 . Figure 3 This is a cross-sectional view of an optical structure 300 according to some embodiments of the present invention. A grating coupler 130 is adjacent to the core layer 120 and is configured to receive a laser beam 160a that has an offset angle due to misalignment of the optical system. The illumination area of ​​the laser beam 160a is larger than the effective coupling area R of the grating coupler 130. eff Compared to Figure 1A The optical structure 100 in the middle, Figure 3 The incident angle of the laser 160a in the optical structure 300 is shifted by an offset angle Δθ, thereby forming a new optical region 164a. The optical region 164a forms a new lens focal length F', a new focal point P', and a new angle θ'. Figure 3 The focal point P' of the optical structure 300 is outside the grating coupler 130. Exposed to Figure 3 The light region 164a on the surface of the grating coupler 130 is larger than the area exposed on the surface. Figure 1A The light area 164 on the surface of the grating coupler 130. Figure 3 The focal length F' of the lens in the middle is greater than Figure 1A The focal length F of the lens in the image. Figure 3 The angle θ' in is less than Figure 1AThe angle θ in the image. In some embodiments, the offset angle Δθ may be ±2 degrees, ±5 degrees, ±10 degrees, or ±20 degrees. The microlens 150 is located above the overlay 140, wherein when the laser 160a enters the microlens 150, the microlens 150 is configured to focus the laser 160a onto the effective coupling region R of the grating coupler 130. eff In the middle. Although the laser 160a is deflected, the optical region 164a still covers the effective coupling region R of the grating coupler 130. eff Furthermore, the new angle θ' is smaller than angle θ, meaning that the new incident angle resulting from the offset angle Δθ of the laser beam 160a is smaller than the designed effective coupling angle of the grating coupler 130. Therefore, the laser 160a can still be coupled and transmitted within the core layer 120. The optical structure of this invention can provide larger alignment tolerances within the optical structure, thereby improving the overall coupling efficiency of the optical structure used for biodetection. It should be noted that, for clarity of discussion, the following optical structure is illustrated, and the offset of the laser 160 should also be included therein.

[0058] It should be understood that, Figure 3 Can contain Figure 1A The substrate 110 in the middle, and may further include Figure 2 The underlying layer 210. Similarly, the layer below... Figures 4 to 7 as well as Figures 12 to 15 Can contain Figure 1A The substrate 110 in the middle, and may further include Figure 2 The underlayer 210.

[0059] Figure 4 , Figure 5 , Figure 6 and Figure 7 Cross-sectional views of optical structures 100a, 100b, 100c, and 100d according to some alternative embodiments of the present invention.

[0060] Please also refer to Figure 1A , Figure 4 and Figure 5 The difference between optical structures 100a, 100b, and optical structure 100 lies in the size of the opening 172. For example... Figure 4 As shown, the opening 172a of the metal shield 170a of optical structure 100a is larger than the opening 172 of the metal shield 170 of optical structure 100. The effective beam EBa of optical structure 100a is larger than the effective beam EB of optical structure 100. The light region 164a of optical structure 100a is larger than the light region 164 of optical structure 100, and the angle in light region 164a is in the range of -θ to θ. This is because light region 164a is focused and exposed in the effective coupling region R. eff Furthermore, the incident angle is within the effective coupling angle of the grating coupler 130, so the laser 160 (reference) Figure 1A This will be coupled and transmitted in the core layer 120. Therefore, the grating coupling efficiency will be improved. Figure 5 As shown, the opening 172b of the metal shield 170b of the optical structure 100b is located on the upper left side of the microlens 150. The light region 164b of the optical structure 100b forms an angle -θ. Because the light region 164b is focused and exposed in the effective coupling region R... eff Since the incident angle is within the effective coupling angle of the grating coupler 130, the laser 160 will be coupled and transmitted in the core layer 120. In some embodiments, the angle θ is in the range of 0 to 50 degrees, depending on the effective coupling angle of the grating coupler.

[0061] Please refer to Figure 1A and Figure 6 The difference between optical structure 100c and optical structure 100 lies in the position of the metal shield 170. For example... Figure 6 As shown, the metal shield 170c is located below the microlens 150. In other words, the metal shield 170c is disposed between the microlens 150 and the grating coupler 130. More specifically, the metal shield 170c is located between the microlens 150 and the overlay 140. The metal shield 170c has an opening 172c to allow a portion of the laser 160 to enter the grating coupler 130. This is because the light region 164c is focused and exposed in the effective coupling region R. eff Since the incident angle is within the effective coupling angle of the grating coupler 130, the laser 160 will be coupled and transmitted in the core layer 120.

[0062] Please refer to Figure 1A and Figure 7 The difference between optical structure 100d and optical structure 100 lies in the configuration of the upper cladding layer 140 and the air gap 710. In optical structure 100, the upper cladding layer 140 is replaced by the air gap 710, as... Figure 7 As shown. In some embodiments, the thickness T of the air gap 710 is in the range of 10 μm to 10 mm, such as 0.05 mm, 0.1 mm, 0.5 mm, 1 mm or 5 mm.

[0063] Figure 8 , Figure 9A , Figure 10A and Figure 11A The figures shown are cross-sectional views of optical structures 800, 800a, 800b, and 800c according to some alternative embodiments of the present invention. It should be noted that... Figure 1A , Figure 8 , Figure 9A , Figure 10A and Figure 11A The main difference lies in the position of the grating coupler 130. For example... Figure 1A As shown, the grating coupler 130 is embedded in the core layer 120.

[0064] Please refer to Figure 8 In the optical structure 800, the grating coupler 130 is located on the surface 122 of the core layer 120 facing the microlens 150, and a portion of the core layer 120 is located between the grating coupler 130 and the substrate 110. Specifically, the grating coupler 130 is below the microlens 150 and above the core layer 120, and is embedded in the overlay layer 140. In some embodiments, the material of the grating coupler 130 is the same as the material of the core layer 120. In some embodiments, the material of the grating coupler 130 is different from the material of the core layer 120. Figure 8 A partial enlarged view of the grating coupler 130 in the image can be found in the reference image. Figure 1B .

[0065] Please refer to Figure 9A In optical structure 800a, grating coupler 130 is disposed on the surface 124 of core layer 120 facing substrate 110, and a portion of core layer 120 is located between microlens 150 and grating coupler 130. More specifically, grating coupler 130 is embedded in substrate 110. Please refer to... Figure 9B , Figure 9B draw Figure 9A A partial enlarged view of the grating coupler 130. The continuous surfaces of the grating coupler 130 (top surface 132, sidewall 136, bottom surface 134, and sidewall 138) face the substrate 110.

[0066] Please refer to Figure 10A Compared to optical structure 800a, optical structure 800b also includes a metal reflector 1010. Please refer to [reference needed]. Figure 10B , Figure 10B draw Figure 10A A partial enlarged view of the grating coupler 130. A metal reflector 1010 is disposed on the surface of the grating coupler 130 facing the substrate 110 (top surface 132, sidewall 136, bottom surface 134 and sidewall 138).

[0067] Please refer to Figure 11A Compared to optical structure 100, optical structure 800c also includes a metal reflector 1010. Specifically, the grating coupler 130 and the metal reflector 1010 are embedded in the core layer 120. Please refer to... Figure 11B , Figure 11B draw Figure 11AA partial enlarged view of the grating coupler 130. The grating coupler 130 has a surface (top surface 132, sidewall 136, bottom surface 134, and sidewall 138) facing the substrate 110 and a sidewall 139 adjacent to this surface. A metal reflector 1010 is disposed on the surface (top surface 132, sidewall 136, bottom surface 134, and sidewall 138) and the sidewall 139 of the grating coupler 130.

[0068] Figure 12 , Figure 13 , Figure 14 and Figure 15 The figures shown are cross-sectional views of optical structures 1200, 1200a, 1200b, and 1200c according to some alternative embodiments of the present invention. It should be noted that... Figure 8 , Figure 9A , Figure 10A , Figure 11A as well as Figure 12 , Figure 13 , Figure 14 , Figure 15 The main difference lies in the configuration of the overlying layer 140 and the air gap 710. In detail, Figure 8 , Figure 9A , Figure 10A and Figure 11A The overlying layer 140 in the middle is Figure 12 , Figure 13 , Figure 14 and Figure 15 The air gap 710 is replaced. Repeated element symbols are used to indicate the same or similar features, and the above description also applies to the embodiments described below, and the details therein will not be repeated.

[0069] Please refer to Figure 16 . Figure 16 This is a cross-sectional view of an optical structure 1600 according to some alternative embodiments of the present invention. In detail, Figure 16 The optical structure in 1600 is similar to Figure 5 The optical structure 100b is included, but the optical structure 1600 also includes a substrate 110 below the core layer 120 and the grating coupler 130.

[0070] Figure 17A for Figure 16 A top view of the metal shield 170b of the optical structure 1600 in the image. Figure 17B for Figure 16 A top view of the substrate 110, core layer 120 and grating coupler 130 of the optical structure 1600. Figure 17C For along Figure 17B A cross-sectional view of the substrate 110, core layer 120, and grating coupler 130 along line A-A'. Figure 17AAs shown, the metal shield 170b has a linear shape. Figure 16 As shown, the cross-sectional shape of the microlens 150 is semi-cylindrical. (As...) Figure 17B As shown, the core layer 120 contains a planar waveguide.

[0071] Figure 18A for Figure 16 A top view of the metal shield 170b of the optical structure 1600 in the image. Figure 18B for Figure 16 A top view of the substrate 110, core layer 120 and grating coupler 130 of the optical structure 1600. Figure 18C For along Figure 18B A cross-sectional view of the substrate 110, core layer 120, and grating coupler 130 of line B-B'. (See attached image.) Figure 18A As shown, the grating coupler 130 includes a curved shape. (As...) Figure 18B As shown, the core layer 120 contains multiple channel waveguides.

[0072] Figure 19 and Figure 20 for Figure 16 A top view of the substrate 110, core layer 120 and grating coupler 130 of the optical structure 1600. Figure 21A , Figure 21B , Figure 21C and Figure 21D For along Figure 19 A cross-sectional view of line C-C'. Similarly, Figure 21A , Figure 21B , Figure 21C and Figure 21D Along Figure 20 A cross-sectional view of line D-D'.

[0073] Figure 21A and Figure 21B Each grating coupler 130 in the grating coupler has multiple grooves. Figure 21C and Figure 21D Each grating coupler 130 has multiple protrusions. In some embodiments, the material of the grating coupler 130 is different from the material of the core layer 120. Figure 21A , Figure 21B , Figure 21C and Figure 21D In the middle, laser 160 (reference) Figure 1A This is coupled to the grating coupler 130 and then propagated in the core layer 120. In some embodiments, the grating coupler 130 has a tapered thickness, such as... Figure 21A or Figure 21C As shown.

[0074] Please refer to Figures 22A to 22F . Figures 22A to 22FA grating coupler 130 (reference) is provided for some embodiments of the present invention. Figure 1B Cross-sectional views of various grating structures are shown. The grating coupler 130 includes at least one of a stepgrating structure 130a, a blazed grating structure 130b, and a slanted grating structure 130c-130f. Please refer again to... Figure 1B A partial enlarged view of the grating coupler 130. The grating coupler 130 has a grating period p and a height h. Figures 22A to 22F The grating structure in the image can be selectively used for Figure 1B The grating coupler 130 is included. Furthermore, according to laser 160 (reference 160)... Figure 1A ) or laser 160a (reference) Figure 3 Direction of transmission (e.g., to the right or left), Figures 22A to 22F The grating structure in the grating can be a mirror-symmetric structure. For example, the first vertical sidewall 221 of the stepped grating structure 130a can face to the right, the inclined sidewall 224 of the blazed grating structure 130b can face to the right, or the first inclined sidewall 225 of the inclined grating structures 130c-130f can face to the right.

[0075] Figure 22A A stepped grating structure 130a of the grating coupler 130 is illustrated. In some embodiments, the stepped grating structure 130a has n orders, where n is in the range of 3 to 16. For example, n is 4, 6, 8, 10, 12, or 14. More specifically... Figure 22A A third-order stepped grating structure is illustrated. The stepped grating structure 130a includes a first vertical sidewall 221, a second vertical sidewall 222, and a horizontal surface 223. The horizontal surface 223 is adjacent to the first vertical sidewall 221 and the second vertical sidewall 222. In some embodiments, the stepped grating structure 130a has a top width Wt of 80 nm, a bottom width Wb of 300 nm, a height h of 400 nm, a first vertical sidewall 221 with a height of 200 nm, a second vertical sidewall 222 with a height of 200 nm, and a horizontal surface 223 with a width of 220 nm.

[0076] Figure 22BA blazed grating structure 130b of a grating coupler 130 is illustrated. The blazed grating structure 130b includes inclined sidewalls 224. The inclined sidewalls 224 extend from the top to the bottom of the blazed grating structure 130b, and the width of the blazed grating structure 130b gradually increases from the top to the bottom. In some embodiments, the bottom width Wb of the blazed grating structure 130b is 400 nm and the height h of the blazed grating structure 130b is 400 nm.

[0077] Figures 22C to 22F The diagram illustrates tilted grating structures 130c-130f of the grating coupler 130. Each of the tilted grating structures 130c-130f includes a first tilted sidewall 225, a second tilted sidewall 226, and a top surface 227. The top surface 227 is adjacent to the first tilted sidewall 225 and the second tilted sidewall 226. Each first tilted sidewall 225 in the tilted grating structures 130c-130f has a first tilt, and each second tilted sidewall 226 in the tilted grating structures 130c-130f has a second tilt. In some embodiments, the first tilt is the same as the second tilt. In some embodiments, the first tilt is less than the second tilt.

[0078] In some implementations, the bottom width Wb is 180 nm, the top width Wt is 180 nm, and the height h is 400 nm, such as... Figure 22C As shown. In some embodiments, the bottom width Wb is 228 nm, the top width Wt is 136 nm, and the height h is 400 nm, such as... Figure 22D As shown. In some embodiments, the bottom width Wb is 260 nm, the top width Wt is 100 nm, and the height h is 400 nm, such as... Figure 22E As shown. In some embodiments, the bottom width Wb is 280 nm, the top width Wt is 80 nm, and the height h is 400 nm, such as... Figure 22F As shown.

[0079] Figure 23A , Figure 23B , Figure 24A , Figure 24B , Figure 25A , Figure 25B , Figure 26A and Figure 26B To illustrate the effects of different grating structures on the incident angle of green light with a wavelength of 532 nm according to some embodiments of the present invention, an intensity graph is plotted. Specifically, a stepped grating structure 130a, a blazed grating structure 130b, and tilted grating structures 130c-130f are used in the simulation. More specifically, the grating period p is 400 nm and the height h is 400 nm (see reference...). Figure 1BThe simulation results show the relationship between different incident angles of green light and different refractive indices of the grating coupler 130 and the overlay 140. It should be understood that "intensity" used here represents the coupling efficiency of the grating coupler 130, and "incident angle" represents the angle relative to the normal direction of the surface of the grating coupler 130. Furthermore, "full width at half maximum (FWHM)" can be understood as the effective coupling angle of the grating coupler. In some embodiments, rigorous coupled wave analysis (RCWA) is used.

[0080] Please refer to Figure 23A and Figure 23B .exist Figure 23A and Figure 23B In the simulation results, the refractive index of the grating coupler 130 is 1.9, and the refractive index of the upper cladding layer 140 is 1. In other words, the upper cladding layer 140 is an air gap 710 (reference). Figure 7 ).exist Figure 23A In this study, when the incident angle is less than approximately 20 degrees, the stepped grating structure 130a, the blazed grating structure 130b, and the tilted grating structure 130c exhibit high intensity. Figure 23B In the case of an incident angle less than approximately 40 degrees, tilted grating structures 130c, 130d, 130e, and 130f exhibit high strength.

[0081] Please refer to Figure 24A and Figure 24B .exist Figure 24A and Figure 24B In the simulation results, the refractive index of the grating coupler 130 is 2.35, and the refractive index of the upper cladding layer 140 is 1. In other words, the upper cladding layer 140 is an air gap 710 (reference). Figure 7 ).exist Figure 24A In the process, the intensity of the stepped grating structure 130a and the blazed grating structure 130b is greater than that of the tilted grating structure 130c. However, when the incident angle is less than approximately 20 degrees, the tilted grating structure 130c still exhibits high intensity. Figure 24B In the above, when the incident angle is less than approximately 40 degrees, tilted grating structures 130c, 130d, 130e, and 130f exhibit high strength. The effective coupling angle tolerance of tilted grating structure 130f is greater than that of tilted grating structure 130c.

[0082] Please refer to Figure 25A and Figure 25B .exist Figure 25A and Figure 25B In the simulation results, the refractive index of the grating coupler 130 is 1.9, and the refractive index of the overlay 140 is 1.47. Figure 25A In the process, the intensity of the tilted grating structure 130c is greater than that of the stepped grating structure 130a and the blazed grating structure 130b. Figure 25B In the above, as the incident angle increases, the tilted grating structures 130c, 130d, 130e, and 130f have similar intensities.

[0083] Please refer to Figure 26A and Figure 26B .exist Figure 26A and Figure 26B In the simulation results, the refractive index of the grating coupler 130 is 2.35, and the refractive index of the overlay 140 is 1.47. Figure 26A In the case where the incident angle is less than approximately 20 degrees, the intensity of the tilted grating structure 130c is greater than that of the stepped grating structure 130a and the blazed grating structure 130b. Figure 26B In the case of incident angle less than about 20 degrees, tilted grating structures 130c, 130d, 130e and 130f have high intensity.

[0084] although Figures 23A to 26B The simulation results for green light with a wavelength of 532 nm are shown, but simulations of other wavelengths (e.g., 488 nm and 633 nm) can also be performed. In the simulation results, the stepped grating structure 130a, the blazed grating structure 130b, and the tilted grating structures 130c-130f exhibit good coupling efficiency and a large effective coupling angle tolerance to a certain extent.

[0085] The optical structure of this invention incorporates a microlens structure for converting a large, collimated laser beam into convergent, focused light exposed over an effective coupling region. This invention provides various grating structures, such as n-order (n>=3), blazed, or tilted gratings, which feature larger effective coupling angles (half-wavelength full width at half maximum (FWHM)) and high coupling efficiency. This allows for the coupling of more energy from a large laser beam and / or the coupling of multiple wavelengths into a grating waveguide to excite fluorescently labeled biomolecules. This invention also provides large alignment tolerances (including x, y, z axes and incident angle) within the optical structure, thereby improving the overall coupling efficiency of the optical structure for biosensing.

[0086] The above description is only a preferred embodiment of the present invention, but it is not intended to limit the scope of the present invention. Any person skilled in the art can make further improvements and changes on this basis without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims of this application.

Claims

1. An optical structure, characterized by, Include: A grating coupler, configured to receive laser light; The core layer, adjacent to the grating coupler; and A microlens is located above the grating coupler, wherein a metal shield covers the microlens. This metal shield has an opening to allow the laser beam to enter the effective coupling region of the grating coupler. The opening in the metal shield is configured to allow a portion of the laser beam to enter the microlens, and the opening has an angle range of -50 degrees to 50 degrees. The effective coupling region is a region in which the laser can couple and propagate within the core layer. An optical region covers the effective coupling region of the grating coupler, and this optical region is a region that allows the laser to couple into the grating coupler.

2. The optical structure of claim 1, wherein, The metal shield is positioned between the microlens and the grating coupler.

3. The optical structure of claim 1, wherein, The laser has an offset angle, and the irradiation area of ​​the laser is larger than the effective coupling area of ​​the grating coupler, wherein the offset angle is in the range of -20 degrees to 20 degrees.

4. The optical structure as described in claim 1, further comprising: A substrate, covered by the core layer, wherein the substrate comprises sapphire or glass, and the refractive index of the substrate is in the range of 1.45 to 2.0; and An overcoat layer covering the core layer, wherein the overcoat layer comprises silicon oxide or a polymer, the refractive index of the core layer is greater than the refractive index of the overcoat layer, the refractive index of the overcoat layer at visible light wavelength is less than 1.6 and the dielectric constant of the overcoat layer is less than 0.00001.

5. The optical structure of claim 4 further comprises an undercoating layer located between the substrate and the core layer, wherein the refractive index of the undercoating layer at visible wavelengths is less than 1.6 and the dielectric constant of the undercoating layer is less than 0.00001, and the substrate comprises silicon or complementary metal-oxide-semiconductor.

6. The optical structure of claim 1, wherein, The grating coupler is embedded in the core layer and has a linear shape when viewed from above. The microlens has a semi-cylindrical cross-section and the core layer contains a planar waveguide.

7. The optical structure of claim 1, wherein, The grating coupler is embedded in the core layer, which has a curved shape when viewed from above, and the core layer contains multiple channel waveguides.

8. The optical structure of claim 4, wherein, The grating coupler is embedded in the core layer and has a surface facing the substrate and a sidewall adjacent to the surface. The optical structure also includes a metal reflector disposed on the surface and the sidewall of the grating coupler.

9. The optical structure of claim 4, wherein, The grating coupler is disposed on the surface of the core layer facing the microlens, a portion of the core layer is located between the grating coupler and the substrate, wherein the material of the grating coupler is different from the material of the core layer, and the grating coupler has a tapered thickness.

10. The optical structure of claim 4, further comprising a metal reflector disposed on the surface of the grating coupler facing the substrate, wherein the grating coupler is disposed on the surface of the core layer facing the substrate, and a portion of the core layer is located between the microlens and the grating coupler.

11. The optical structure of claim 1, wherein, The grating coupler is a stepped grating structure, which includes a first vertical sidewall, a second vertical sidewall, and a horizontal surface adjacent to the first vertical sidewall and the second vertical sidewall.

12. The optical structure of claim 1, wherein, The grating coupler is a blazed grating structure that includes sloped sidewalls extending from a top of the blazed grating structure to a bottom of the blazed grating structure, and a width of the blazed grating structure gradually increases from the top of the blazed grating structure to the bottom of the blazed grating structure.

13. The optical structure of claim 1, wherein, The grating coupler is a tilted grating structure that includes a first sloped sidewall, a second sloped sidewall, and a top surface adjoining the first sloped sidewall and the second sloped sidewall.

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