Fluorescent sensing chip

Abstract

The invention discloses a fluorescent sensing chip which comprises a light inlet coupling structure and a light outlet coupling structure, and a grating is arranged between the light inlet coupling structure and the light outlet coupling structure. A fluorescent material layer is arranged on the grating, or a transmission waveguide is arranged between the grating and the light inlet coupling structure, and a fluorescent material layer is arranged on the transmission waveguide; the grating is configured to reflect the input pump light and to transmit the fluorescent light. According to the fluorescent sensing chip disclosed by the invention, the Bragg grating filter is integrated, so that on-chip pump light filtering and pump light reflection are realized, the effect of at least two times of the optical path of the pump light is achieved, but the transmission distance of fluorescent light is not changed, and the transmission loss of the fluorescent light is not changed.

Description

Technical Field

[0001] This invention relates to the field of integrated optoelectronics technology, and more specifically to a fluorescence sensing chip. Background Technology

[0002] Fluorescence sensing identifies the type and dosage of an analyte by detecting changes in its fluorescence color and intensity through the interaction between the fluorescent sensing material and the analyte. Traditional fluorescence sensors are bulky, costly, and unstable; chip integration can effectively solve these problems.

[0003] The related technology discloses a fluorescent sensing chip, see [link to relevant documentation]. Figure 1 and Figure 2 Pump light (488nm) enters the sensing chip from the input optical coupling structure 1 (such as a vertical grating coupler), and then propagates in the silicon nitride waveguide 2 within the chip. A fluorescent material (such as BTD, with a fluorescence wavelength of 540nm) is coated on top of the silicon nitride waveguide. When light passes through the fluorescent material, fluorescence is excited. The fluorescence and residual pump light then exit from the output optical coupling structure 8 (such as a grating coupler). This chip integrates an optical waveguide with a fluorescent material coated on top. Pump light excites fluorescence when it passes through the optical waveguide. When the analyte interacts with the fluorescent material, it causes a change in the fluorescence spectrum. The analyte can be identified by analyzing the fluorescence spectrum.

[0004] Figure 1 , Figure 2 Insufficient absorption of pump light by the fluorescent material can lead to residual pump light in the output light. Therefore, an external filter is needed to filter out the pump light. Additionally, in Figure 1 , Figure 2 In this structure, the interaction path between the pump light and the fluorescent material is the same as the fluorescence transmission path. If this path is too long, it will lead to a large fluorescence transmission loss; if it is too short, it will lead to insufficient fluorescence excitation. Therefore, there is a contradiction between the fluorescence excitation intensity and the fluorescence transmission loss.

[0005] The above scheme achieves chip integration of the core fluorescent sensing device, but two problems still need to be solved: 1. Both pump light and fluorescence are collected by the output port inside the chip, requiring a filter to be configured outside the chip to filter the pump light, increasing the complexity of the system; 2. The contradiction between fluorescence transmission loss and fluorescence excitation intensity remains unresolved. Specifically, before the pump light is completely absorbed by the fluorescent material, the longer the waveguide, the more fully the waveguide interacts with the fluorescent material, and the stronger the fluorescence produced. However, a longer waveguide also causes greater transmission loss. The end result is that although strong fluorescence is produced, very little light can be detected from the chip. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art, and proposes a fluorescence sensing chip.

[0007] In a first aspect, the present invention discloses a fluorescence sensing chip, including an input light coupling structure, an output light coupling structure, and further including a first grating, a second grating, and a mode multiplexing / demultiplexer;

[0008] The first grating is disposed between the light-inlet coupling structure and the light-outlet coupling structure, and a fluorescent material layer is disposed on the first grating; or, a transmission waveguide is disposed between the first grating and the light-inlet coupling structure, and a fluorescent material layer is disposed on the transmission waveguide.

[0009] The first grating is configured to reflect the input pump light and change the transmission mode of the pump light, and to transmit fluorescence.

[0010] The second grating is configured to reflect the input pump light;

[0011] The mode multiplexer / demultiplexer is configured to receive a first transmission mode optical signal reflected by a first grating and transmit the optical signal to an incoming optical coupling structure; receive a second transmission mode optical signal reflected by a first grating and transmit the optical signal to a second grating, while simultaneously changing the transmission mode of the optical signal; receive a first transmission mode optical signal entering the optical coupling structure and transmit the optical signal to a first grating; and receive a first transmission mode optical signal reflected by a second grating and transmit the optical signal to a first grating, while simultaneously changing the transmission mode of the optical signal.

[0012] In some embodiments, the mode multiplexer-demultiplexer includes a first coupling waveguide and a second coupling waveguide. One end of the first coupling waveguide is connected to the incoming light coupling structure, and the other end of the first coupling waveguide is directly or via a transmission waveguide connected to one end of a first grating. The other end of the first grating is connected to the outgoing light coupling structure, and the second coupling waveguide is connected to the second grating.

[0013] And / or,

[0014] When the fluorescent material layer is disposed on the transmission waveguide, the transmission waveguide is located between the mode multiplexer / demultiplexer and the first grating;

[0015] And / or,

[0016] The second grating includes a second grating waveguide, and second grating teeth are respectively provided on both sides of the second grating waveguide. The second grating teeth on both sides of the second grating waveguide are distributed in a mirror symmetrical manner along the central axis of the second grating waveguide.

[0017] In some embodiments, the first grating includes a first grating waveguide, and first grating teeth are respectively provided on both sides of the first grating waveguide. The first grating teeth on both sides of the first grating are asymmetrically distributed, and the first grating teeth are periodically distributed in an alternating manner on both sides of the first grating waveguide.

[0018] In some embodiments, the height of the first grating teeth arranged sequentially from both ends of the first grating waveguide toward the center gradually increases.

[0019] In some embodiments, the first grating has a reflection band centered at λ with a bandwidth of Δλ, where λ is the center wavelength of the pump light, and the fluorescence wavelength generated by the pump light is not within the range of the reflection band.

[0020] In some embodiments, the first grating includes a first grating waveguide, with first grating teeth on both sides of the first grating waveguide. The first grating is divided into a fluorescence excitation section and an optical signal separation section along the length of the first grating waveguide. The fluorescence excitation section is close to the light input coupling structure, and the optical signal separation section is close to the light output coupling structure. A fluorescent material layer is disposed on the fluorescence excitation section. The optical signal separation section is configured to reflect the input pump light and transmit the fluorescence.

[0021] In some embodiments, the maximum reflection wavelength of the fluorescence excitation section is less than or equal to the minimum reflection wavelength of the optical signal separation section;

[0022] And / or, the grating period of the fluorescence excitation section is less than the grating period of the optical signal separation section.

[0023] In some embodiments, the fluorescence excitation section includes a first grating section and a second grating section, and the optical signal separation section includes a third grating section and a fourth grating section. The first grating section and the second grating section use the same grating period, and the third grating section and the fourth grating section use the same grating period. The grating periods of the first grating section and the second grating section are less than the grating periods of the third grating section and the fourth grating section. The first grating section is an input-side apodized grating, the second grating section is a uniform grating, the third grating section is a uniform grating, and the fourth grating section is an output-side apodized grating.

[0024] Secondly, the present invention discloses a fluorescent sensing chip, including an input light coupling structure and an output light coupling structure, wherein a third grating is disposed between the input light coupling structure and the output light coupling structure.

[0025] A fluorescent material layer is disposed on the third grating, or a transmission waveguide is disposed between the third grating and the light-incoming coupling structure, and a fluorescent material layer is disposed on the transmission waveguide;

[0026] The third grating is configured to reflect the input pump light while maintaining the transmission mode, and to transmit fluorescence.

[0027] In some embodiments, the third grating includes a third grating waveguide, and third grating teeth are respectively provided on both sides of the third grating waveguide. The third grating teeth on both sides of the third grating waveguide are distributed in a mirror-symmetrical manner along the central axis of the third grating waveguide.

[0028] In some embodiments, the third grating has a reflection band centered at λ with a bandwidth of Δλ, where λ is the center wavelength of the pump light, and the fluorescence wavelength generated by the pump light is not within the range of the reflection band.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The fluorescence sensing chip of this invention achieves on-chip pump light filtering and pump light reflection by integrating a Bragg grating filter, achieving at least twice the optical path length of the pump light, while keeping the fluorescence transmission distance unchanged and thus keeping the fluorescence transmission loss constant. Attached Figure Description

[0031] Figure 1 A side view of a fluorescent sensing chip disclosed in the relevant technology;

[0032] Figure 2 This is a partial top view of a fluorescent sensor chip disclosed in the relevant technology.

[0033] Figure 3 This is a schematic diagram of the structure of a fluorescence sensing chip provided in one embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the structure of a fluorescence sensing chip provided in another embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of the structure of TE0 / TE1 BG provided in an embodiment of the present invention;

[0036] Figure 6 The reflectance spectrum of TE0 / TE1 BG (the horizontal axis represents the wavelength of light, and the vertical axis represents the reflectance R of light).

[0037] Figure 7 The transmission spectrum of TE0 / TE1 BG (the horizontal axis represents the wavelength of light, and the vertical axis represents the transmittance T of light).

[0038] Figure 8 for Figure 4 A schematic diagram of the first forward pass of the fluorescent material in TE0 mode;

[0039] Figure 9 for Figure 4 A schematic diagram of the second reverse pass of the fluorescent material in TE1 mode;

[0040] Figure 10 for Figure 4 A schematic diagram of the third forward pass of the fluorescent material in TE1 mode;

[0041] Figure 11 for Figure 4 A schematic diagram of the fourth reverse pass of the fluorescent material in TE0 mode;

[0042] Figure 12 This is a schematic diagram of the structure of a fluorescence sensing chip provided in another embodiment of the present invention;

[0043] Figure 13 This is a schematic diagram of the structure of a fluorescence sensing chip provided in another embodiment of the present invention;

[0044] Figure 14 The reflectance spectrum of the portion of TE0 / TE1 BG coated with fluorescent material.

[0045] In the attached diagram, 1 is the input optical coupling structure, 2 is the output optical coupling structure, 3 is the second grating, 4 is the mode multiplexer / demultiplexer, 5 is the transmission waveguide, 6 is the fluorescent material layer, 7 is the first grating, and 8 is the third grating. Detailed Implementation

[0046] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "comprising," "including," etc., mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. The terms "connected," "linked," etc., are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up," "down," "left," "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly. "A plurality" in this invention refers to at least two.

[0048] In the various figures, the same elements are represented by similar reference numerals. For clarity, not all parts in the figures are drawn to scale. Furthermore, some well-known parts may not be shown in the figures.

[0049] Many specific details of the invention, such as the structure, materials, dimensions, processing methods, and techniques of the components, are described below to provide a clearer understanding of the invention. However, as those skilled in the art will understand, the invention may be implemented without following these specific details.

[0050] See Figure 3 This invention provides a fluorescence sensing chip, which includes an input light coupling structure 1 and an output light coupling structure 2, with a third grating 8 disposed between the input light coupling structure 1 and the output light coupling structure 2.

[0051] The third grating 8 is wholly or partially coated with a fluorescent material layer 6, or a transmission waveguide 5 is provided between the third grating 8 and the light-initiating coupling structure 1, and a fluorescent material layer 6 is provided on the transmission waveguide 5.

[0052] The third grating 8 is configured to reflect the input pump light and keep the reflected light signal transmission mode unchanged, and to transmit fluorescence.

[0053] The third grating 8 includes a third grating waveguide, with third grating teeth on both sides of the waveguide. The third grating teeth on both sides of the waveguide are mirror-symmetrically distributed along the central axis of the waveguide. The third grating reflects the input pump light, but the transmission mode remains unchanged. In some embodiments, the third grating is a TE0 / TE0BG.

[0054] The fluorescence sensing chip of this invention achieves on-chip pump light filtering and pump light reflection by integrating a Bragg grating filter, achieving twice the optical path length of the pump light, while keeping the fluorescence transmission distance unchanged and thus keeping the fluorescence transmission loss constant.

[0055] In some embodiments, the light inlet coupling structure 1 is a grating coupler for the light inlet, and the light outlet coupling structure 2 is a grating coupler for the light outlet.

[0056] In some embodiments, the third grating is disposed on the first silicon oxide layer, which is disposed on a substrate. The substrate is a silicon (Si) substrate. The areas of the third grating not covered by the phosphor material layer 6 are covered by a second silicon oxide layer, i.e., a cladding layer.

[0057] As described above, a transmission waveguide 5 is provided between the third grating and the light-incoming coupling structure 1, and a fluorescent material layer 6 is provided on the transmission waveguide 5. The transmission waveguide 5 is disposed on the first silicon oxide layer.

[0058] This invention provides another fluorescence sensing chip, which includes an input light coupling structure 1, an output light coupling structure 2, a first grating 7, a second grating 3, and a mode multiplexer / demultiplexer 4. The first grating 7 is disposed between the input light coupling structure 1 and the output light coupling structure 2.

[0059] See Figure 12 A fluorescent material layer 6 is disposed (coated) on the first grating 7, or, see... Figure 13 The upper portion of the first grating 7 is provided with (coated) a fluorescent material layer 6, or, see... Figure 4 A transmission waveguide 5 is provided between the first grating 7 and the light-inlet coupling structure 1, and a fluorescent material layer 6 is provided on the transmission waveguide 5;

[0060] The first grating 7 is configured to reflect the input pump light and change the transmission mode of the reflected light signal (e.g., converting the first transmission mode light signal into the second transmission mode light signal or the second transmission mode light signal into the first transmission mode light signal) and to transmit fluorescence.

[0061] The second grating 3 is configured to reflect the input pump light;

[0062] The mode multiplexer / demultiplexer 4 is configured to receive a first transmission mode optical signal reflected by the first grating 7 and transmit the optical signal to the optical coupling structure 1; receive a second transmission mode optical signal reflected by the first grating and transmit the optical signal to the second grating, while simultaneously changing the transmission mode of the optical signal (e.g., converting the second transmission mode optical signal into the first transmission mode optical signal); receive a first transmission mode optical signal entering the optical coupling structure 1 and transmit the optical signal to the first grating; and receive a first transmission mode optical signal reflected by the second grating and transmit the optical signal to the first grating, while simultaneously changing the transmission mode of the optical signal (e.g., converting the first transmission mode optical signal into the second transmission mode optical signal).

[0063] In some embodiments, the first transmission mode optical signal is TE0 mode and the second transmission mode optical signal is TE1 mode.

[0064] In some embodiments, the first grating, the second grating, and the mode multiplexer / demultiplexer 4 are disposed on a first silicon oxide layer, which is disposed on a substrate. The substrate is a silicon (Si) substrate. The areas of the first grating not covered by the phosphor material layer 6 are covered by the second silicon oxide layer, i.e., a cladding layer. The second grating and the mode multiplexer / demultiplexer 4 are also covered by the second silicon oxide layer, i.e., a cladding layer.

[0065] For example, a transmission waveguide 5 is provided between the first grating and the light-incoming coupling structure 1, and a fluorescent material layer 6 is provided on the transmission waveguide 5. The transmission waveguide 5 is disposed on the first silicon oxide layer.

[0066] In some embodiments, the first grating is a TE0 / TE1 BG (or a TE0 / TE1 Bragg grating). The second grating is a TE0 / TE0 BG (or a TE0 / TE0 Bragg grating).

[0067] The fluorescent sensing chip of this invention achieves on-chip pump light filtering by integrating a Bragg grating filter. At the same time, by cascading two types of Bragg grating filters, TE0 / TE1 and TE0 / TE0, three reflections of the pump light are achieved, resulting in a four-fold optical path of the pump light, but the transmission distance of the fluorescence remains unchanged. That is, the interaction length between the pump light and the fluorescent material is increased by three times, but the transmission loss of the fluorescence remains unchanged.

[0068] This invention employs TE0 / TE1BG (braggrating) integrated within the chip to reflect and filter the pump light. Figure 5 The diagram shows the structure of TE0 / TE1BG. The grating teeth of TE0 / TE1BG are asymmetrically distributed, which can reflect light in TE0 mode into TE1 mode, or reflect light in TE1 mode into TE0 mode. Figure 6 The reflection spectrum of TE0 / TE1BG is shown. It can be seen that TE0 / TE1BG has a reflection band centered at 488nm and approximately 10nm wide, which can reflect the 488nm pump light. Figure 6 As can be seen from the mode field distribution diagram, the mode field of the reflected wavelength is the TE1 mode. Figure 7 The transmission spectra of TE0 / TE1BG are shown. It can be seen that the transmittance of the pump light at 488nm is below -50dB, exhibiting excellent filtering effect, while the transmittance at the 540nm fluorescence wavelength is close to 0dB, with almost no loss, allowing complete transmission. Figure 7 The mode field distribution diagram shows that the mode field at the 540nm transmission wavelength is TE0 mode. It can be seen that TE0 / TE1BG can completely reflect the 488nm pump light and convert it from TE0 mode to TE1 mode, while the 540nm fluorescence can be completely transmitted and maintain its mode. In this way, pump light filtering is completed within the chip, eliminating the need for external filters.

[0069] In some embodiments, the mode multiplexer / demultiplexer 4 includes a first coupling waveguide and a second coupling waveguide. One end of the first coupling waveguide is connected to the incoming light coupling structure 1, and the other end of the first coupling waveguide is directly or via the transmission waveguide 5 connected to one end of the first grating. The other end of the first grating is connected to the outgoing light coupling structure 2, and the second coupling waveguide is connected to the second grating.

[0070] In some embodiments, when the fluorescent material layer 6 is disposed on the transmission waveguide 5, the transmission waveguide 5 is located between the mode multiplexer / demultiplexer 4 and the first grating.

[0071] In some embodiments, the second grating includes a second grating waveguide, and second grating teeth are respectively provided on both sides of the second grating waveguide. The second grating teeth on both sides of the second grating waveguide are distributed in a mirror symmetrical manner along the central axis of the second grating waveguide.

[0072] In some embodiments, the first grating has a reflection band centered at λ with a bandwidth of Δλ, where λ is the center wavelength of the pump light, and the fluorescence wavelength generated by the pump light is not within the range of the reflection band.

[0073] In some embodiments, the first grating includes a first grating waveguide, and first grating teeth are respectively provided on both sides of the first grating waveguide. The first grating teeth on both sides of the first grating are asymmetrically distributed, and the first grating teeth are periodically distributed in an alternating manner on both sides of the first grating waveguide.

[0074] In some embodiments, the height of the first grating teeth arranged sequentially from both ends of the first grating waveguide toward the center gradually increases.

[0075] In some embodiments, the first grating has a reflection band centered at λ with a bandwidth of Δλ, where λ is the center wavelength of the pump light, and the fluorescence wavelength generated by the pump light is not within the range of the reflection band.

[0076] Figure 8 This is a schematic diagram showing the first forward pass of light in TE0 mode through a fluorescent composite waveguide (fluorescent material and transmission waveguide 5), as shown. Figure 8 As shown, when TE0 mode light enters the fluorescent material composite waveguide through the vertical grating, part of the pump light interacts with the fluorescent material, the pump light is consumed, and fluorescence is excited. The remaining pump light is emitted at TE0 / TE1 BG, and the mode of the reflected light changes to TE1 mode. Figure 9 This is a schematic diagram of light traveling in the TE1 mode for the second reverse direction through a fluorescent composite waveguide, as shown below. Figure 9 As shown, the reflected TE1 mode pump light passes through the fluorescent composite waveguide again, where part of the pump light further excites fluorescence, and the remaining pump light is converted into TE0 mode by a mode multiplexer (MDM). This TE0 mode pump light is then reflected back in TE0 mode after reflection via a TE0 / TE0 BG. Figure 9 As can be seen from the schematic diagram, the grating teeth of TE0 / TE0 BG are symmetrically distributed vertically. Figure 10This is a schematic diagram showing the third forward pass of light in TE1 mode through a fluorescent composite waveguide, as shown below. Figure 10 As shown, the TE0 mode pump light reflected back by the TE0 / TE0 BG passes through the MDM again and is converted to the TE1 mode. Then, the TE1 mode pump light passes through the fluorescent composite waveguide for the third time, and part of the pump light further excites the fluorescence. Figure 11 This is a schematic diagram showing light traveling in the TE0 mode for the fourth time through a fluorescent composite waveguide, as shown below. Figure 11 As shown, the remaining TE1 mode pump light is emitted at TE0 / TE1 BG, and the reflected light changes to TE0 mode. The TE0 mode pump light passes through the fluorescent composite waveguide for the fourth time, and part of the pump light further excites the fluorescence, while the remaining pump light is emitted from the grating coupler at the inlet. It is important to note that the residual pump light and the fluorescence exit from different vertically coupled gratings, so there is no crosstalk between them.

[0077] Figure 12 This is a schematic diagram of a fluorescent sensor chip coated with fluorescent material on the TE0 / TE1 BG. Figure 4 In this structure, fluorescent material is coated on transmission waveguide 5 (such as a silicon nitride waveguide). The excited fluorescence needs to pass through the first grating (such as TE0 / TE1 BG) to reach the output coupling structure 2 (vertical grating coupler) at the output port. The first grating (such as TE0 / TE1 BG) is about 40 μm long, which will cause some transmission loss. In addition, the silicon nitride strip waveguide has strong light confinement ability, and the interaction between the pump light and the fluorescent material is relatively weak. Figure 12 In this process, fluorescent material is coated on the first grating (such as TE0 / TE1 BG). By calculating the refractive index difference introduced by the fluorescent material, and then adjusting the grating period of the first grating (such as TE0 / TE1 BG), the reflection spectrum of the first grating (such as TE0 / TE1 BG) can still be adjusted to 488nm. The beneficial effects of this design are that, on the one hand, the interaction area between the grating waveguide and the fluorescent material is large, making it easier to excite fluorescence; on the other hand, after the fluorescence comes out from the first grating (such as TE0 / TE1 BG), it can be directly output from the chip through the vertical grating coupler, reducing fluorescence transmission loss.

[0078] Figure 12 The difficulty with the Chinese approach lies in the batch-to-batch consistency of the fluorescent material coating process. This leads to changes in the refractive index, which in turn alters the reflection spectrum of the first grating (e.g., TE0 / TE1 BG), preventing it from effectively reflecting the pump light. To retain... Figure 12 The proposed scheme leverages the strong interaction between the grating waveguide and the pump light, the short transmission distance of the fluorescence, and avoids the risk of alteration in the reflection spectrum of the first grating (such as TE0 / TE1 BG). Figure 13 The plan, for Figure 12 The first grating (TE0 / TE1 BG) in the process has been improved.

[0079] In other embodiments, see Figure 13 The first grating includes a first grating waveguide, with first grating teeth on both sides. The first grating is divided into a fluorescence excitation section and an optical signal separation section along its length. The fluorescence excitation section is located near the input light coupling structure 1, and the optical signal separation section is located near the output light coupling structure 2. A fluorescent material layer 6 is disposed on the fluorescence excitation section. The optical signal separation section is configured to reflect the input pump light and transmit fluorescence. Instead of a fluorescent material layer 6, a silicon oxide layer is disposed on the optical signal separation section.

[0080] The first grating teeth on both sides of the fluorescence excitation section are asymmetrically distributed, and are periodically distributed in an alternating manner on both sides of the first grating waveguide. Similarly, the first grating teeth on both sides of the optical signal separation section are asymmetrically distributed, and are periodically distributed in an alternating manner on both sides of the first grating waveguide.

[0081] In some embodiments, the reflection band of the fluorescence excitation section does not overlap with the reflection band of the optical signal separation section, so that the fluorescence excitation section does not reflect the pump light or fluorescence.

[0082] In some embodiments, the maximum reflection wavelength of the fluorescence excitation section is less than or equal to the minimum reflection wavelength of the optical signal separation section.

[0083] In some embodiments, the grating period of the fluorescence excitation section is smaller than the grating period of the optical signal separation section.

[0084] In some embodiments, see Figure 13 The fluorescence excitation section includes a first grating section P1 and a second grating section P2, and the optical signal separation section includes a third grating section P3 and a fourth grating section P4. The first grating section P1 and the second grating section P2 use the same grating period T1, and the third grating section P3 and the fourth grating section P4 use the same grating period T2. The grating period T1 of the first grating section P1 and the second grating section P2 is less than the grating period T2 of the third grating section P3 and the fourth grating section P4. The first grating section P1 is an input-side apodized grating, the second grating section P2 is a uniform grating, the third grating section P3 is a uniform grating, and the fourth grating section P4 is an output-side apodized grating.

[0085] In some embodiments, along the direction of light propagation, the grating tooth height of the first grating segment P1 gradually increases to form an input-side apodized grating, and the grating tooth height of the fourth grating segment P4 gradually decreases to form an output-side apodized grating. The direction of light propagation refers to the direction from the input light coupling structure 1 to the output light coupling structure 2.

[0086] In some embodiments, all the grating teeth of the second grating segment P2 have the same height and are equal to the maximum grating tooth height of the first grating segment P1, and all the grating teeth of the third grating segment P3 have the same height and are equal to the maximum grating tooth height of the fourth grating segment P4.

[0087] In some embodiments, the grating tooth height of the second grating segment P2 is equal to the grating tooth height of the third grating segment P3.

[0088] The direction of light propagation refers to the direction from the light-inlet coupling structure 1 to the light-outlet coupling structure 2.

[0089] Figure 13 The first grating in the design employs a four-segment design, including grating segment P1, grating segment P2, grating segment P3, and grating segment P4. Segments P1 and P2 use the same grating period T1 and are coated with fluorescent material. P1 is an apodized grating, and P2 is a uniform grating. Due to the short period lengths of the gratings in segments P1 and P2, the reflected wavelength is also relatively short. Figure 14 As shown, the reflection wavelength of gratings P1 and P2 is 460nm, avoiding the pump light wavelength. Therefore, gratings P1 and P2 only increase the interaction between the pump light and the fluorescent material, without reflecting the pump light. Gratings P3 and P4 use the same grating period T2, with silicon dioxide material on top. The function of grating P3 is to transition the grating period from T1 to T2, while also reflecting the pump light. P4 is an apodized grating. The overall reflection spectrum of P1-P4 is as follows: Figure 14 As shown, a reflection band of 488nm is added to the right of the 460nm reflection wavelength of the P1-P2 grating. This added 488nm reflection band is caused by the P3-P4 grating, therefore the pump light is reflected in the P3-P4 grating. Figure 13 The advantage of this design scheme lies in the fact that the material on the pump light reflection grating (P3-P4 segment) is silicon oxide grown using a coating process, which offers good stability and consistency, ensuring that the reflection band of the P3-P4 segment grating is at 488nm. Simultaneously, the P1-P2 segment grating increases the interaction between the pump light and the fluorescent material, but does not reflect the 488nm pump light; therefore, strict requirements are not placed on the refractive index of the coated fluorescent material. Furthermore, the P3 segment grating is very short, and the length of the P3-P4 segment grating is shorter than... Figure 4 The length of the TE0 / TE1 BG is much shorter, which can reduce fluorescence transmission loss.

[0090] This invention proposes to achieve a pump light path length of 4 times by using two types of grating filters, TE0 / TE1 and TE0 / TE0, while the fluorescence path length remains the same. This increases the interaction between the pump light and the fluorescent material, while ensuring that the transmission loss of the fluorescence remains unchanged.

[0091] The present invention further proposes a scheme in which fluorescent material is coated on the TE0 / TE1 grating. This scheme can enhance the interaction between pump light and fluorescent material through the grating structure, while shortening the distance from the fluorescence to the output grating coupler and reducing the transmission loss of fluorescence.

[0092] This invention further proposes a scheme where fluorescent material is coated on top of the TE0 / TE1 grating. The TE0 / TE1 grating adopts a four-segment design. The P1 and P2 segments are coated with fluorescent material and employ a short-period design, so that the reflected wavelength deviates from the pump light wavelength, serving only to enhance the interaction between the pump light and the fluorescent material. The P3 and P4 segments are coated with silicon oxide and employ a long-period design, so that the reflection spectrum of the grating can stably operate near the pump light wavelength, serving to reflect the pump light. At the same time, the P3 and P4 segments are relatively short, so the fluorescence transmission loss is also small.

[0093] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A fluorescent sensor chip, comprising an input light coupling structure and an output light coupling structure, characterized in that: It also includes a first grating, a second grating, and a mode multiplexing / demultiplexer; The first grating is disposed between the light-inlet coupling structure and the light-outlet coupling structure, and a fluorescent material layer is disposed on the first grating; or, a transmission waveguide is disposed between the first grating and the light-inlet coupling structure, and a fluorescent material layer is disposed on the transmission waveguide. The first grating is configured to reflect the input pump light and change the transmission mode of the pump light, and to transmit fluorescence. The second grating is configured to reflect the input pump light; The mode multiplexer / demultiplexer is configured to receive a first transmission mode optical signal reflected by a first grating and transmit the optical signal to an incoming optical coupling structure; receive a second transmission mode optical signal reflected by a first grating and transmit the optical signal to a second grating, while simultaneously changing the transmission mode of the optical signal; receive a first transmission mode optical signal entering the optical coupling structure and transmit the optical signal to a first grating; and receive a first transmission mode optical signal reflected by a second grating and transmit the optical signal to a first grating, while simultaneously changing the transmission mode of the optical signal.

2. The fluorescent sensing chip as described in claim 1, characterized in that: The mode multiplexing and demultiplexing unit includes a first coupling waveguide and a second coupling waveguide. One end of the first coupling waveguide is connected to the incoming light coupling structure, and the other end of the first coupling waveguide is directly or via a transmission waveguide connected to one end of a first grating. The other end of the first grating is connected to the outgoing light coupling structure, and the second coupling waveguide is connected to the second grating. And / or, When the fluorescent material layer is disposed on the transmission waveguide, the transmission waveguide is located between the mode multiplexer / demultiplexer and the first grating; And / or, The second grating includes a second grating waveguide, and second grating teeth are respectively provided on both sides of the second grating waveguide. The second grating teeth on both sides of the second grating waveguide are distributed in a mirror symmetrical manner along the central axis of the second grating waveguide.

3. The fluorescent sensing chip as described in claim 1, characterized in that: The first grating includes a first grating waveguide, and first grating teeth are respectively provided on both sides of the first grating waveguide. The first grating teeth on both sides of the first grating are asymmetrically distributed, and the first grating teeth are periodically distributed in an alternating manner on both sides of the first grating waveguide.

4. The fluorescent sensing chip as described in claim 3, characterized in that: The height of the first grating teeth, which are arranged sequentially from both ends of the first grating waveguide toward the center, gradually increases.

5. The fluorescent sensing chip according to any one of claims 1 to 4, characterized in that: The first grating has a reflection band centered at λ with a bandwidth of Δλ, where λ is the center wavelength of the pump light, and the fluorescence wavelength generated by the pump light is not within the range of the reflection band.

6. The fluorescent sensing chip as described in claim 1, characterized in that: The first grating includes a first grating waveguide, with first grating teeth on both sides of the first grating waveguide. The first grating is divided into a fluorescence excitation section and an optical signal separation section along the length of the first grating waveguide. The fluorescence excitation section is close to the light input coupling structure, and the optical signal separation section is close to the light output coupling structure. A fluorescent material layer is disposed on the fluorescence excitation section. The optical signal separation section is configured to reflect the input pump light and transmit the fluorescence.

7. The fluorescence sensing chip as described in claim 6, characterized in that: The maximum reflection wavelength of the fluorescence excitation section is less than or equal to the minimum reflection wavelength of the optical signal separation section; And / or, the grating period of the fluorescence excitation section is less than the grating period of the optical signal separation section.

8. The fluorescent sensing chip as described in claim 6 or 7, characterized in that: The fluorescence excitation section includes a first grating section and a second grating section, and the optical signal separation section includes a third grating section and a fourth grating section. The first grating section and the second grating section use the same grating period, and the third grating section and the fourth grating section use the same grating period. The grating periods of the first grating section and the second grating section are shorter than the grating periods of the third grating section and the fourth grating section. The first grating section is an input-side apodized grating, the second grating section is a uniform grating, the third grating section is a uniform grating, and the fourth grating section is an output-side apodized grating.

9. A fluorescent sensor chip, comprising an input light coupling structure and an output light coupling structure, characterized in that: A third grating is provided between the light-increasing coupling structure and the light-outcreasing coupling structure; A fluorescent material layer is disposed on the third grating, or a transmission waveguide is disposed between the third grating and the light-incoming coupling structure, and a fluorescent material layer is disposed on the transmission waveguide; The third grating is configured to reflect the input pump light while maintaining the transmission mode, and to transmit fluorescence.

10. The fluorescent sensing chip as described in claim 9, characterized in that: The third grating includes a third grating waveguide, and third grating teeth are respectively provided on both sides of the third grating waveguide. The third grating teeth on both sides of the third grating waveguide are distributed in a mirror symmetrical manner along the central axis of the third grating waveguide.

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