An on-chip fluorescence excitation and collection system
By integrating the fluorescence excitation and acquisition system on the chip, efficient fluorescence excitation and acquisition is achieved using waveguide structure and photonic crystal array, solving the problems of large size and complex operation of traditional biofluorescence detection equipment, and realizing the application of portable detection.
Patent Information
- Application Number
- CN202210254618.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-03-15
- Publication Date
- 2025-08-05
- Estimated Expiration
- 2042-03-15
AI Technical Summary
Traditional biofluorescence detection methods require large equipment and professional personnel to operate, which is difficult to meet the needs of rapid clinical testing, and the system is large in size and cannot achieve portable detection.
An on-chip fluorescence excitation and acquisition system was designed, integrating fluorescence excitation, enhancement and acquisition functions. It uses waveguide structure and photonic crystal array to achieve efficient excitation and acquisition of fluorescence, including rectangular waveguides, Y-type beam splitting waveguides, slotted waveguides, Y-type beam combined waveguides and photonic crystal arrays. Gallium nitride material is used to reduce absorption and achieve separation of excitation light and fluorescence.
The system is miniaturized and portable fluorescence detection has been realized, the excitation and collection efficiency has been improved, and the dependence on traditional fluorescence detection equipment has been reduced. It is suitable for biological detection, drug research and development, and food safety.
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Figure CN114689510B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of fluorescence excitation and collection systems in biotechnology, and in particular to a fluorescence excitation and collection system based on a waveguide structure to excite dyes to generate and collect broadband fluorescence in a specific band. Background Art
[0002] In the field of modern biology, fluorescence is widely used in the detection of various biological molecules and chemical samples, and plays a very important role in biological detection. When a beam of excitation light irradiates a fluorescent material, the material absorbs photons with the same intrinsic frequency as its own and enters an excited state. Since the excited state at this time is unstable, the material will quickly return from the excited state to the ground state, thereby emitting light of other wavelengths in the form of electromagnetic radiation. This process is called fluorescence. Traditional biological fluorescence detection methods require the construction of a spatial optical path, the use of large equipment, and professional personnel to operate. Therefore, its application is limited to laboratory environments and it is difficult to meet the needs of rapid clinical detection. With the development of real-time fluorescence detection technology, miniature portable fluorescence detection systems are playing an increasingly important role in biological detection, drug research and development, food safety and other fields. Summary of the Invention
[0003] To address the shortcomings of existing technologies, the present invention provides an on-chip fluorescence excitation and acquisition system featuring a compact size, high excitation and acquisition efficiency, and ease of integration. This invention is achieved through the following technical solutions: an on-chip fluorescence excitation and acquisition system that integrates the fluorescence excitation, enhancement, and acquisition processes and functions on a chip. The system specifically comprises a light source module, a fluorescence excitation and enhancement module, a fluorescence filter module, and a supporting substrate. The fluorescence excitation and enhancement module comprises a rectangular waveguide, a Y-shaped beam-splitting waveguide, a slot waveguide, and a Y-shaped beam-combining waveguide. The fluorescence filter module is a photonic crystal array consisting of 20 to 30 cylindrical holes hollowed out of a rectangular waveguide. The supporting substrate comprises a transition layer and a heterojunction substrate. The entire system is structured in three layers. At the bottom is the heterojunction substrate, used to prepare and grow the required waveguide structure. A transition layer is grown on top of the heterojunction substrate using molecular beam epitaxy. The two layers are tightly bonded together and serve as a nitrogen source for the waveguide growth. On top of this transition layer, a fluorescence excitation and enhancement module and a fluorescence filter module are also grown, also using molecular beam epitaxy, from left to right. These modules excite the dye to produce fluorescence and filter the excitation light, respectively. The fluorescence excitation and enhancement module and the fluorescence filter module are closely connected.
[0004] The waveguide structures such as the fluorescence excitation and enhancement module and the fluorescence filter module are all made of gallium nitride (GaN) material with low absorption at visible light wavelengths.
[0005] The fluorescence excitation and enhancement module and the fluorescence filter module are grown on the transition layer through molecular beam epitaxy and are closely attached to the transition layer.
[0006] The fluorescence excitation and enhancement module and the fluorescence filtering module are closely fitted and connected, and are integrated in space. The fluorescence excitation and enhancement module is located on the left side of the fluorescence filtering module.
[0007] The fluorescence excitation and enhancement module includes four parts, which are a rectangular waveguide, a Y-shaped beam splitting waveguide, a slot waveguide, and a Y-shaped beam combining waveguide from left to right. These four parts are also directly connected.
[0008] The rectangular waveguide is located at the leftmost end of the entire system and is the input end of the entire system. Its left input end is connected to the light source through an optical fiber. The excitation light is coupled into the rectangular waveguide through the optical fiber and then enters the on-chip fluorescence system.
[0009] The rectangular waveguide has a width of 190-210 nm and a height of 280-320 nm. Single-mode laser light can be transmitted in the waveguide to avoid the influence of higher-order modes.
[0010] The right output end of the rectangular waveguide is directly connected to the Y-shaped beam splitting waveguide, and the excitation light can directly enter the Y-shaped beam splitting waveguide from the rectangular waveguide.
[0011] The Y-shaped beam splitting waveguide has two output ends and is a one-to-two structure, used to split the input excitation light into two beams of light, and the two output ends on the right are directly connected to the two input ends of the slot waveguide.
[0012] The slot waveguides are a pair of parallel rectangular waveguides. The left end of the slot waveguides houses two input ports connected to a Y-shaped beam-splitting waveguide, while the right end houses two output ports connected to a Y-shaped beam-combining waveguide. When excitation light is split by the Y-shaped beam-splitting waveguide and enters the slot waveguide, the light in the parallel waveguides can be coupled into the slot by adjusting the width of the slit. This generates a high-intensity light pattern, known as a slit mode, in the slot. This pattern can excite the dye in the slot to produce fluorescence. Higher light intensity results in higher excitation efficiency.
[0013] The width of the parallel waveguide of the slot waveguide is 150nm, the height is 280-320nm, and the width of the slit slot between the two parallel waveguides is 35-60nm.
[0014] The fluorescence excited by the slot waveguide will be re-coupled into the slot waveguide and continue to be transmitted along the waveguide, and then transmitted from the two output ends of the slot waveguide to the Y-type beam combining waveguide. At the same time, the excitation light will also be transmitted along the waveguide to the Y-type beam combining waveguide.
[0015] The Y-shaped beam combining waveguide has two input ends connected to the two output ends of the slot waveguide, forming a two-in-one structure for receiving excited fluorescence and excitation light.
[0016] The angle between the two output ends of the Y-shaped beam splitting waveguide and the angle between the two input ends of the Y-shaped beam combining waveguide are 10-15 degrees, which can improve the transmittance of light during beam splitting and combining, thereby improving the efficiency of fluorescence excitation and collection.
[0017] The fluorescence filter module is a photonic crystal array, the left input end of which is connected to the output end of the Y-shaped beam combining waveguide. It receives the excited fluorescence and the transmitted excitation light, and is used to reflect and filter the transmitted excitation light, retaining only the fluorescence, thereby completing the purpose of separating the excitation light and fluorescence and collecting the fluorescence.
[0018] The photonic crystal array has a width of 190-210 nm and a height of 280-320 nm. It is composed of 20-30 cylindrical holes equally spaced on a rectangular waveguide. The distance between the centers of two cylindrical holes is 130-140 nm, and the diameter of the cylindrical holes is 60-75 nm.
[0019] An optical fiber interface is reserved at the right output end of the photonic crystal array for connecting to external equipment. As the output end of the entire system, the excited and collected fluorescence is coupled out from this output end.
[0020] The supporting substrate comprises a transition layer and a heterojunction substrate, and is a two-layer structure. The bottom layer is the heterojunction substrate, and the upper layer is the transition layer, and the two are tightly fitted.
[0021] The thickness of the transition layer is 10 to 20 nm, and the material is a Group III nitride, such as aluminum nitride (AlN), which is used to provide a nitrogen source for the growth of the surface nitride film.
[0022] The heterojunction substrate is below the transition layer, has a thickness of micrometer level, and is made of sapphire.
[0023] Beneficial effects
[0024] 1. By using a waveguide structure to couple excitation light and generate fluorescence, the system volume is reduced, and subsequent fluorescence detection can be integrated into the chip, realizing a portable on-chip fluorescence excitation and collection system.
[0025] 2. By using gallium nitride as the material of the waveguide structure, the waveguide's absorption of excitation light and fluorescence is reduced, thereby improving the efficiency of fluorescence excitation and collection.
[0026] 3. The slot waveguide structure enables simultaneous fluorescence excitation and collection, eliminating the need for traditional fluorescence detection microscopes.
[0027] 4. By adjusting the slit width of the slot waveguide, the mode light intensity in the slot waveguide is enhanced, thereby improving the efficiency of fluorescence excitation.
[0028] 5. The photonic crystal array is used for filtering, reflecting the excitation light and transmitting the fluorescence, thus achieving the purpose of separating the excitation light and fluorescence.
[0029] 6. The purpose of broadband fluorescence excitation is achieved by using the difference in reflection and transmittance of the photonic crystal array for broadband wavelengths. The reflectivity of the excitation light in the wavelength range of 500-540nm is maintained above 90%, and the transmittance of the fluorescence in the range of 600-650nm is maintained above 70%. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 This is the three-dimensional structure diagram of the on-chip fluorescence excitation and collection system.
[0031] Figure 2 A top view of the on-chip fluorescence excitation and collection system.
[0032] Figure 3 This is the front view of the on-chip fluorescent module.
[0033] Figure 4 This is a side view of the on-chip fluorescent module.
[0034] Figure 5 This is the schematic diagram of the on-chip fluorescence excitation and collection system.
[0035] Figure 6 The influence of slit width on the proportion of slit mode intensity
[0036] Figure 7 Reflection and transmission spectra of on-chip fluorescence excitation and collection system
[0037] Reference numerals
[0038] 1- Light source
[0039] 2- Single-mode fiber optic patch cord
[0040] 3- Rectangular waveguide
[0041] 4- Y-type beam splitting waveguide
[0042] 5-slot waveguide
[0043] 6- Y-type beam combining waveguide
[0044] 7- Photonic crystal array
[0045] 8- Cylindrical hole
[0046] 9- Fiber optic interface
[0047] 10- Transition layer
[0048] 11- Heterojunction substrate DETAILED DESCRIPTION
[0049] In order to illustrate the present invention more clearly, the following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Specific embodiment 1
[0051] Based on the waveguide-coupled on-chip fluorescence excitation and collection system, here we take the transition layer thickness of 10nm, the slit spacing of 60nm, the Y-type beam splitting waveguide and the Y-type beam combining waveguide with an angle of 10°, the waveguide structure width of 190nm, the height of 280nm, the number of cylindrical holes in the photonic crystal array of 20, the diameter of 60nm, the spacing of 130nm, and the excitation light wavelength of 520nm as an example. The final fluorescence wavelength is 612nm and the transmittance is 85%:
[0052] (1) If Figures 1 to 4 As shown, an on-chip fluorescence excitation and collection system includes a light source 1, a single-mode optical fiber 2, a rectangular waveguide 3, a Y-type beam-splitting waveguide 4, a slot waveguide 5, a Y-type beam-combining waveguide 6, a photonic crystal array 7, an optical fiber interface 9, a transition layer 10, and a heterojunction substrate 11. The slot waveguide 5 is a pair of parallel waveguides with a slit in the middle, the slit having a width of 60 nm. The light source 1 is connected to the rectangular waveguide 3 via the single-mode optical fiber 2. The rectangular waveguide 3, the Y-type beam-splitting waveguide 4, the slot waveguide 5, the Y-type beam-combining waveguide 6, and the photonic crystal array 7 form a waveguide structure, which is directly connected to each other and made of gallium nitride (GaN). The excitation light is transmitted through this path in the fluorescence excitation and collection system.
[0053] (2) If Figure 2 As shown, the light source 1 is connected to the input rectangular waveguide 3 of the fluorescence excitation and collection module through the single-mode optical fiber 2, the light source 1 is turned on, and the excitation light with a wavelength of 520nm (green light, Figure 5 The light (indicated by the black solid arrow in the figure) will be input into the rectangular waveguide 3 through the single-mode optical fiber 2. Due to the limitation of the aspect ratio of the waveguide, the fundamental mode of the excitation light will be transmitted forward along the waveguide. When passing through the Y-shaped beam splitting waveguide 4, as shown in FIG. Figure 5 As shown, the excitation light is split into two beams of light and transmitted along the two output ends of the Y-shaped beam splitting waveguide 4 respectively, with a splitting ratio of 1:1.
[0054] (3) After the two beams of excitation light are split in step (2), they are transmitted to the slot waveguide 5, corresponding to the upper and lower parallel waveguides in the slot waveguide 5. Figure 5As shown in the figure, light coupling occurs between parallel waveguides with small spacing, thereby generating a stable and high-intensity light field in the middle slit slot, which is called slit mode. When the slit slot width is 60nm, as shown in the figure, Figure 6 As shown, the light intensity in the slit accounts for 32.1% of the total light intensity.
[0055] (4) The slit mode generated in (3) reacts with the dye placed in the slit of the slot waveguide 5, and efficiently excites the generation of fluorescence with a wavelength of 612 nm (yellow, in Figure 5 Then, the excited fluorescence and the excitation light coupled into the slit groove are coupled into the two parallel waveguides of the groove waveguide 5 and continue to be transmitted forward.
[0056] (5) After the fluorescence excitation and collection process in (4), the fluorescence and excitation light will be transmitted through the two parallel waveguides of the slot waveguide 5 to the two input ends of the Y-type beam-combining waveguide 6. After beam combining, they will be output from the output end of the Y-type beam-combining waveguide 6 to the photonic crystal array 7. At this time, the transmitted light contains two wavelengths of light, 520nm excitation light and 612nm fluorescence.
[0057] (6) The mixed light composed of fluorescence and excitation light transmitted to the photonic crystal array 7 in (5) will be filtered under the action of the photonic crystal composed of 20 equally spaced cylindrical holes with a diameter of 60nm and a spacing of 130nm, as shown in the following example: Figure 7 As shown, the reflectivity of the excitation light with a wavelength of 520 nm is 98%, and the transmittance of the fluorescence with a wavelength of 612 nm is 85%. The photonic crystal array 7 separates the fluorescence from the excitation light and outputs the excited fluorescence at the optical fiber interface 9 at the output end of the system.
[0058] (7) If Figure 7 As shown, the photonic crystal array 7 not only has high reflectivity for the excitation light with a wavelength of 520nm and high transmittance for the fluorescence with a wavelength of 612nm, but also maintains a reflectivity of more than 90% for the excitation light wavelength range of 500~540nm, and a transmittance of more than 70% for the fluorescence within the range of 600~650nm. This feature achieves the purpose of broadband fluorescence excitation. Specific embodiment 2
[0060] Based on the waveguide-coupled on-chip fluorescence excitation and collection system, here we take the transition layer thickness of 10nm, the slit spacing of 35nm, the Y-type beam splitting waveguide and the Y-type beam combining waveguide with an angle of 15°, the waveguide structure width of 210nm, the height of 320nm, the number of cylindrical holes in the photonic crystal array of 30, the diameter of 75nm, the spacing of 140nm, and the excitation light wavelength of 520nm as an example. The final fluorescence wavelength is 612nm, and the fluorescence transmittance is 86%:
[0061] (1) If Figures 1 to 4 As shown, an on-chip fluorescence excitation and collection system includes a light source 1, a single-mode optical fiber 2, a rectangular waveguide 3, a Y-type beam-splitting waveguide 4, a slot waveguide 5, a Y-type beam-combining waveguide 6, a photonic crystal array 7, an optical fiber interface 9, a transition layer 10, and a heterojunction substrate 11. The slot waveguide 5 is a pair of parallel waveguides with a slit in the middle, the slit having a width of 35 nm. The light source 1 is connected to the rectangular waveguide 3 via the single-mode optical fiber 2. The rectangular waveguide 3, Y-type beam-splitting waveguide 4, slot waveguide 5, Y-type beam-combining waveguide 6, and photonic crystal array 7 form a waveguide structure, which is directly connected to each other and made of gallium nitride (GaN). The excitation light is transmitted through this path in the fluorescence excitation and collection system.
[0062] (2) If Figure 2 As shown, the light source 1 is connected to the input rectangular waveguide 3 of the fluorescence excitation and collection module through the single-mode optical fiber 2, the light source 1 is turned on, and the excitation light with a wavelength of 520nm (green light, Figure 5 The light (indicated by the black solid arrow in the figure) will be input into the rectangular waveguide 3 through the single-mode optical fiber 2. Due to the limitation of the aspect ratio of the waveguide, the fundamental mode of the excitation light will be transmitted forward along the waveguide. When passing through the Y-shaped beam splitting waveguide 4, as shown in FIG. Figure 5 As shown, the excitation light is split into two beams of light and transmitted along the two output ends of the Y-shaped beam splitting waveguide 4 respectively, with a splitting ratio of 1:1.
[0063] (3) After the two beams of excitation light are split in step (2), they are transmitted to the slot waveguide 5, corresponding to the upper and lower parallel waveguides in the slot waveguide 5. Figure 5 As shown in the figure, light coupling occurs between parallel waveguides with small spacing, thereby generating a stable and high-intensity light field in the middle slit slot, which is called slit mode. When the slit slot width is 35nm, as shown in the figure, Figure 6 As shown, the light intensity in the slit accounts for 31.7% of the total light intensity.
[0064] (4) The slit mode generated in (3) reacts with the dye placed in the slit of the slot waveguide 5, and efficiently excites the generation of fluorescence with a wavelength of 612 nm (yellow, in Figure 5 Then, the excited fluorescence and the excitation light coupled into the slit groove are coupled into the two parallel waveguides of the groove waveguide 5 and continue to be transmitted forward.
[0065] (5) After the fluorescence excitation and collection process in (4), the fluorescence and excitation light will be transmitted through the two parallel waveguides of the slot waveguide 5 to the two input ends of the Y-type beam-combining waveguide 6. After beam combining, they will be output from the output end of the Y-type beam-combining waveguide 6 to the photonic crystal array 7. At this time, the transmitted light contains two wavelengths of light, 520nm excitation light and 612nm fluorescence.
[0066] (6) The mixed light composed of fluorescence and excitation light transmitted to the photonic crystal array 7 in (5) will be filtered under the action of the photonic crystal composed of 30 equally spaced cylindrical holes with a diameter of 75nm and a spacing of 140nm, as shown in the following example: Figure 7 As shown, the reflectivity of the excitation light with a wavelength of 520 nm is 98%, and the transmittance of the fluorescence with a wavelength of 612 nm is 86%. The photonic crystal array 7 separates the fluorescence from the excitation light and outputs the excited fluorescence at the optical fiber interface 9 at the output end of the system.
[0067] (7) If Figure 7 As shown, the photonic crystal array 7 not only has high reflectivity for the excitation light with a wavelength of 520nm and high transmittance for the fluorescence with a wavelength of 612nm, but also maintains a reflectivity of more than 90% for the excitation light wavelength range of 500~540nm, and a transmittance of more than 70% for the fluorescence within the range of 600~650nm. This feature achieves the purpose of broadband fluorescence excitation. Specific embodiment 3
[0069] Based on the waveguide-coupled on-chip fluorescence excitation and collection system, here we take the transition layer thickness of 20nm, the slit spacing of 40nm, the Y-type beam splitting waveguide and the Y-type beam combining waveguide with an angle of 10°, the waveguide structure width of 200nm, the height of 300nm, the number of cylindrical holes in the photonic crystal array of 25, the diameter of 65nm, the spacing of 135nm, and the excitation light wavelength of 536nm (PI dye) as an example. The final fluorescence wavelength is 617nm and the transmittance is 74%:
[0070] (1) If Figures 1 to 4 As shown, an on-chip fluorescence excitation and collection system includes a light source 1, a single-mode optical fiber 2, a rectangular waveguide 3, a Y-type beam-splitting waveguide 4, a slot waveguide 5, a Y-type beam-combining waveguide 6, a photonic crystal array 7, an optical fiber interface 9, a transition layer 10, and a heterojunction substrate 11. The slot waveguide 5 is a pair of parallel waveguides with a slit in the middle, the slit having a width of 40 nm. The light source 1 is connected to the rectangular waveguide 3 via the single-mode optical fiber 2. The rectangular waveguide 3, Y-type beam-splitting waveguide 4, slot waveguide 5, Y-type beam-combining waveguide 6, and photonic crystal array 7 form a waveguide structure, which is directly connected to each other and made of gallium nitride (GaN). The excitation light is transmitted through this path in the fluorescence excitation and collection system.
[0071] (2) If Figure 2 As shown, the light source 1 is connected to the input rectangular waveguide 3 of the fluorescence excitation and collection module through the single-mode optical fiber 2, the light source 1 is turned on, and the excitation light with a wavelength of 536nm (green light, Figure 5The light (indicated by the black solid arrow in the figure) will be input into the rectangular waveguide 3 through the single-mode optical fiber 2. Due to the limitation of the aspect ratio of the waveguide, the fundamental mode of the excitation light will be transmitted forward along the waveguide. When passing through the Y-shaped beam splitting waveguide 4, as shown in FIG. Figure 5 As shown, the excitation light is split into two beams of light and transmitted along the two output ends of the Y-shaped beam splitting waveguide 4 respectively, with a splitting ratio of 1:1.
[0072] (3) After the two beams of excitation light are split in step (2), they are transmitted to the slot waveguide 5, corresponding to the upper and lower parallel waveguides in the slot waveguide 5. Figure 5 As shown in the figure, light coupling occurs between parallel waveguides with small spacing, thereby generating a stable and high-intensity light field in the middle slit slot, which is called slit mode. When the slit slot width is 40nm, as shown in the figure, Figure 6 As shown, the light intensity in the slit accounts for 31.1% of the total light intensity.
[0073] (4) The slit mode generated in (3) reacts with the dye placed in the slit of the slot waveguide 5, and efficiently excites the generation of fluorescence with a wavelength of 617 nm (yellow, in Figure 5 Then, the excited fluorescence and the excitation light coupled into the slit groove are coupled into the two parallel waveguides of the groove waveguide 5 and continue to be transmitted forward.
[0074] (5) After the fluorescence excitation and collection process in (4), the fluorescence and excitation light will be transmitted through the two parallel waveguides of the slot waveguide 5 to the two input ends of the Y-type beam-combining waveguide 6. After beam combining, they will be output from the output end of the Y-type beam-combining waveguide 6 to the photonic crystal array 7. At this time, the transmitted light contains two wavelengths of light, 536nm excitation light and 617nm fluorescence.
[0075] (6) The mixed light composed of fluorescence and excitation light transmitted to the photonic crystal array 7 in (5) will be filtered under the action of the photonic crystal composed of 25 equally spaced cylindrical holes with a diameter of 65nm and a spacing of 135nm, as shown in the following example: Figure 7 As shown, the reflectivity of the excitation light with a wavelength of 536 nm is 99%, and the transmittance of the fluorescence with a wavelength of 617 nm is 74%. The photonic crystal array 7 separates the fluorescence from the excitation light and outputs the excited fluorescence at the optical fiber interface 9 at the output end of the system.
[0076] (7) If Figure 7 As shown, the photonic crystal array 7 not only has high reflectivity for the excitation light with a wavelength of 536nm and high transmittance for the fluorescence with a wavelength of 617nm, but also maintains a reflectivity of more than 90% for the excitation light wavelength range of 500~540nm, and a transmittance of more than 70% for the fluorescence within the range of 600~650nm. This feature achieves the purpose of broadband fluorescence excitation. Specific embodiment 4
[0078] Based on the waveguide-coupled on-chip fluorescence excitation and collection system, here we take the transition layer thickness of 15nm, the slit spacing of 50nm, the Y-type beam splitting waveguide and the Y-type beam combining waveguide with an angle of 15°, the waveguide structure width of 200nm, the height of 300nm, the number of cylindrical holes in the photonic crystal array of 20, the diameter of 70nm, the spacing of 1350nm, and the excitation light wavelength of 536nm (PI dye) as an example. The final fluorescence wavelength is 617nm and the transmittance is 76%:
[0079] (1) If Figures 1 to 4 As shown, an on-chip fluorescence excitation and collection system includes a light source 1, a single-mode optical fiber 2, a rectangular waveguide 3, a Y-type beam-splitting waveguide 4, a slot waveguide 5, a Y-type beam-combining waveguide 6, a photonic crystal array 7, an optical fiber interface 9, a transition layer 10, and a heterojunction substrate 11. The slot waveguide 5 is a pair of parallel waveguides with a slit in the middle, the slit having a width of 50 nm. The light source 1 is connected to the rectangular waveguide 3 via the single-mode optical fiber 2. The rectangular waveguide 3, the Y-type beam-splitting waveguide 4, the slot waveguide 5, the Y-type beam-combining waveguide 6, and the photonic crystal array 7 form a waveguide structure, which is directly connected to each other and made of gallium nitride (GaN). The excitation light is transmitted through this path in the fluorescence excitation and collection system.
[0080] (2) If Figure 2 As shown, the light source 1 is connected to the input rectangular waveguide 3 of the fluorescence excitation and collection module through the single-mode optical fiber 2, the light source 1 is turned on, and the excitation light with a wavelength of 536nm (green light, Figure 5 The light (indicated by the black solid arrow in the figure) will be input into the rectangular waveguide 3 through the single-mode optical fiber 2. Due to the limitation of the aspect ratio of the waveguide, the fundamental mode of the excitation light will be transmitted forward along the waveguide. When passing through the Y-shaped beam splitting waveguide 4, as shown in FIG. Figure 5 As shown, the excitation light is split into two beams of light and transmitted along the two output ends of the Y-shaped beam splitting waveguide 4 respectively, with a splitting ratio of 1:1.
[0081] (3) After the two beams of excitation light are split in step (2), they are transmitted to the slot waveguide 5, corresponding to the upper and lower parallel waveguides in the slot waveguide 5. Figure 5 As shown in the figure, light coupling occurs between parallel waveguides with small spacing, thereby generating a stable and high-intensity light field in the middle slit slot, which is called slit mode. When the slit slot width is 50nm, as shown in the figure, Figure 6 As shown, the light intensity in the slit accounts for 30.8% of the total light intensity.
[0082] (4) The slit mode generated in (3) reacts with the dye placed in the slit of the slot waveguide 5, and efficiently excites the generation of fluorescence with a wavelength of 617 nm (yellow, in Figure 5Then, the excited fluorescence and the excitation light coupled into the slit groove are coupled into the two parallel waveguides of the groove waveguide 5 and continue to be transmitted forward.
[0083] (5) After the fluorescence excitation and collection process in (4), the fluorescence and excitation light will be transmitted through the two parallel waveguides of the slot waveguide 5 to the two input ends of the Y-type beam-combining waveguide 6. After beam combining, they will be output from the output end of the Y-type beam-combining waveguide 6 to the photonic crystal array 7. At this time, the transmitted light contains two wavelengths of light, 536nm excitation light and 617nm fluorescence.
[0084] (6) The mixed light composed of fluorescence and excitation light transmitted to the photonic crystal array 7 in (5) will be filtered under the action of the photonic crystal composed of 20 equally spaced cylindrical holes with a diameter of 70nm and a spacing of 135nm, as shown in the following example: Figure 7 As shown, the reflectivity of the excitation light with a wavelength of 536 nm is 99%, and the transmittance of the fluorescence with a wavelength of 617 nm is 76%. The photonic crystal array 7 separates the fluorescence from the excitation light and outputs the excited fluorescence at the optical fiber interface 9 at the output end of the system.
[0085] (7) If Figure 7 As shown, the photonic crystal array 7 not only has high reflectivity for the excitation light with a wavelength of 536nm and high transmittance for the fluorescence with a wavelength of 617nm, but also maintains a reflectivity of more than 90% for the excitation light wavelength range of 500~540nm, and a transmittance of more than 70% for the fluorescence within the range of 600~650nm. This feature achieves the purpose of broadband fluorescence excitation.
Claims
1. A fluorescence excitation and collection system, characterized in that: include: The light source module, the fluorescence excitation and enhancement module, the fluorescence filter module, the fluorescence output interface, and the supporting substrate are provided. The fluorescence excitation and enhancement module includes four parts: a rectangular waveguide, a Y-shaped beam splitting waveguide, a slot waveguide, and a Y-shaped beam combining waveguide. The rectangular waveguide has one input end and one output end. The Y-shaped beam splitting waveguide has one input end and two output ends, and the angle between the two output ends is 10 to 15 degrees. The slot waveguide is a pair of mutually parallel rectangular waveguides, having two input ends and two output ends, and the two mutually parallel rectangular waveguides constituting the slot waveguide are provided. The width of the slit between the waveguides is 35 to 60 nm, and a fluorescent dye is placed in the slit; the Y-shaped beam-combining waveguide has two input ends and one output end, and the angle between the two input ends is 10 to 15 degrees; the fluorescence filter module has one input end and one output end, and is composed of a photonic crystal array; the fluorescence output interface has one input end and the other end is an interface end for output to downstream devices; the light source module, fluorescence excitation and enhancement module, filter module, and fluorescence output interface are connected and arranged in sequence from left to right on the supporting substrate.
2. The fluorescence excitation and collection system according to claim 1, characterized in that: The supporting substrate includes a transition layer and a heterojunction substrate layer, and the two layers are tightly attached. The transition layer is on the upper side and is a group III nitride; the heterojunction substrate layer is below the transition layer and is made of sapphire.
3. The fluorescence excitation and collection system according to claim 2, characterized in that: The transition layer is made of aluminum nitride.
4. The fluorescence excitation and collection system according to claim 1, characterized in that: The light source module is a visible light laser, or the light source module is a single-mode optical fiber jumper, and the laser is introduced into the fluorescence excitation and enhancement module through the optical fiber.
5. The fluorescence excitation and collection system according to claim 1, characterized in that: The rectangular waveguide has a width of 190 to 210 nm and a height of 280 to 320 nm.
6. The fluorescence excitation and collection system according to claim 1, characterized in that: The photonic crystal array has a width of 190 to 210 nm and a height of 280 to 320 nm. 20 to 30 cylindrical holes are hollowed out at equal intervals on a rectangular waveguide. The distance between the centers of two cylindrical holes is 130 to 40 nm, and the diameter of the cylindrical holes is 60 to 75 nm.
7. The fluorescence excitation and collection system according to any one of claim 2, characterized in that: The thickness of the transition layer is 0-20 nm.
8. The fluorescence excitation and collection system according to any one of claims 1 to 4, wherein the interface end of the fluorescence output interface is an optical fiber interface for connecting to other devices and serving as the output end of the entire system.
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