M-Z optical waveguide temperature sensor of polymer silicon dioxide heterogeneous modulation arm

Abstract

The invention provides an M-Z optical waveguide temperature sensor of a polymer silicon dioxide heterogeneous modulation arm, which comprises a substrate chip with a three-layer film structure, and the substrate chip sequentially comprises a first silicon dioxide layer with a high refractive index, a second silicon dioxide layer with a high refractive index and a third silicon dioxide layer with a high refractive index from top to bottom, a second silica layer having a low refractive index; a base layer; an M-Z optical waveguide structure layer is formed on the second silicon dioxide layer with the low refractive index of the substrate chip and comprises two branch arms, one branch arm is a polymer waveguide, the other branch arm is a silicon dioxide waveguide, and the two branch arms are located on the same plane; in the M-Z optical waveguide structure layer, light is divided into two paths at the input end of the M-Z optical waveguide structure layer, propagates along two branch arms respectively, and then is recombined at the output end of the M-Z optical waveguide structure layer. The sensor has the advantages of low loss, simple process, low cost, high sensing precision, high sensitivity, simple structure, easy integration and the like.

Description

Technical Field

[0001] The invention relates to the technical field of preparing polymer optical waveguide and silicon dioxide waveguide hybrid integrated photonic chip, and in particular to a Mach-Zenhder (MZ) hybrid integrated optical waveguide temperature sensor of polymer silicon dioxide coplanar heterogeneous waveguide modulation arms. Background Art

[0002] Multi-material hybrid integrated photonic chips are an important branch in the field of photonic chips. Hybrid integrated photonic chips use waveguide materials of different properties to integrate on-chip to improve the function and performance of photonic chips. Silica chips are important passive photonic chip materials with low loss and high stability. They have been used in commercial chips such as couplers, beam splitters, and AWGs. Polymer materials are important materials for optical waveguide devices, especially their high thermo-optical coefficient, high biocompatibility, and self-healing properties. They are particularly suitable for thermo-optical devices, wearables, and sensing applications. Optical waveguide temperature sensors are an important direction of hybrid integrated photonic devices of polymers and silica at this stage. This direction mainly uses the high thermo-optical coefficient of polymers to improve the sensor sensitivity of temperature sensors.

[0003] The MZ optical waveguide sensor is an important structure for realizing temperature sensing. Compared with sensing structures such as gratings, the MZ optical waveguide sensor does not require spectral detection, and its preparation does not require sub-micron process precision. The two arms of the existing MZ optical waveguide sensor are mainly waveguides of the same material. By changing the length of the two MZ branch arms or changing the width of the branch arms, an asymmetric MZ is realized. When the temperature changes, the phase difference between the two arms of the asymmetric MZ changes differently, thereby affecting the output light intensity. The temperature and output light intensity are linked to achieve sensing. Although changing the length and width of the two arms can increase the phase difference between the two arms, when the temperature changes, the phase difference of the two arms changes in the same direction (because the thermo-optical coefficient is consistent), which is not conducive to improving the sensing accuracy.

[0004] The existing MZ temperature sensor integration scheme of polymer and silicon dioxide mainly adopts a multilayer film structure, which mainly includes structure 1: using polymer as the waveguide core layer and silicon dioxide as the substrate. This structure uses silicon dioxide as the substrate and cooperates with the photosensitive core layer material, and its processing technology is simple; structure 2, using silicon dioxide grooves as the substrate and polymer as the core layer. This structure is mainly suitable for polymer materials that are not photosensitive and forms a ridge waveguide. The two arms of the above structure MZ also use the same material, which is not conducive to improving the sensing accuracy.

[0005] There is also a multi-layer integrated structure, which first prepares the silicon dioxide chip core layer and cladding, then polishes the surface, and then uses grayscale lithography to prepare polymer waveguides with bevel coupling ports on both sides. When the temperature changes, the two arms of the MZ of this structure change in opposite directions, so the temperature change will bring about a greater phase difference change, so the sensing accuracy is higher, but after the silicon dioxide waveguide is prepared, the polishing cost and preparation efficiency are affected, and special grayscale lithography equipment and photolithography plates are required, which increases the cost of the device. Summary of the invention

[0006] In order to solve the above problems existing in the prior art, the purpose of the present invention is to provide an MZ optical waveguide temperature sensor with a polymer silica heterogeneous modulation arm, which has the advantages of low loss, simple process, low cost, high sensing accuracy, high sensitivity, simple structure, and easy integration.

[0007] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0008] A polymer silicon dioxide heterogeneous modulation arm MZ optical waveguide temperature sensor, comprising:

[0009] The substrate chip has a three-layer film structure, which includes, from top to bottom:

[0010] A first high-refractive-index silicon dioxide layer, whose refractive index is 1.455 to 1.48;

[0011] A second low-refractive-index silicon dioxide layer, whose refractive index is 1.44 to 1.45;

[0012] A base layer, wherein the base layer is a single crystal silicon layer or a low refractive index dioxide layer;

[0013] An MZ optical waveguide structure layer is formed on the second silicon dioxide layer with a low refractive index, and includes two branch arms, one of which is a polymer waveguide and the other is a silicon dioxide waveguide, and the two branch arms are located on the same plane; wherein the silicon dioxide waveguide is obtained by etching the high refractive index silicon dioxide layer in the substrate chip;

[0014] In the MZ optical waveguide structure layer, light is divided into two paths at its input end, propagating along two branch arms respectively, and then reunited at its output end; wherein, due to the different thermo-optic coefficients of the polymer waveguide and the silica waveguide, when the temperature changes, the optical phases of the polymer waveguide and the silica waveguide change in opposite directions, which manifests as a significant change in light intensity at the output end of the MZ optical waveguide structure layer, thereby achieving highly sensitive detection of temperature changes.

[0015] According to the MZ optical waveguide temperature sensor of a polymer silica heterogeneous modulation arm provided by the present invention, the thickness of the first silica layer is 2-8 μm, the thickness of the second silica layer is 3-10 μm, and the thickness of the base layer is 100-1000 μm.

[0016] According to the MZ optical waveguide temperature sensor of a polymer-silicon dioxide heterogeneous modulation arm provided by the present invention, the steps of preparing the polymer waveguide and the silicon dioxide waveguide include:

[0017] Providing a first silicon dioxide layer with a high refractive index to manufacture a silicon dioxide waveguide portion of an MZ optical waveguide structure layer;

[0018] A base sheet of a three-layer membrane structure having a rectangular projection in the vertical direction is selected;

[0019] Evaporating a mask layer on a substrate chip to form a mask layer for a silicon dioxide waveguide;

[0020] Spin-coating photoresist to form a photoresist film layer with a thickness of 0.1 to 5 μm;

[0021] A photoresist mask layer is obtained by introducing a pattern on the photoresist film layer using a photolithography plate or a maskless photolithography machine, performing photolithography and then developing the pattern.

[0022] According to the MZ optical waveguide temperature sensor of a polymer silicon dioxide heterogeneous modulation arm provided by the present invention, when manufacturing the silicon dioxide waveguide, a mask etching agent is used to etch the mask layer to obtain a waveguide mask pattern;

[0023] The waveguide core layer is obtained by plasma etching or ICP etching, and the etching depth is d3;

[0024] The photoresist mask layer is removed with a corresponding photoresist developer, and the waveguide mask pattern is removed with a corresponding solution to obtain a silicon dioxide waveguide chip.

[0025] According to the MZ optical waveguide temperature sensor of the polymer silicon dioxide heterogeneous modulation arm provided by the present invention, a waveguide core material is spin-coated on a silicon dioxide waveguide chip to obtain a polymer waveguide core material film, the film thickness d6 is 1 to 10 μm, which is equal to the waveguide d3 thickness;

[0026] An MZ pattern photoresist is used to perform photolithography or a maskless photolithography machine is used to import a graphic file consistent with the MZ pattern photoresist, and a polymer waveguide is obtained after development, thereby forming an MZ optical waveguide structure.

[0027] According to the MZ optical waveguide temperature sensor of the polymer silicon dioxide heterogeneous modulation arm provided by the present invention, a polymer cladding is spin-coated on the MZ optical waveguide structure, and the thickness d7 of the cladding is 1.5 to 5 μm thicker than d6.

[0028] According to the MZ optical waveguide temperature sensor of the polymer silica heterogeneous modulation arm provided by the present invention, the MZ optical waveguide structure after the cladding is directly cut, and the input and output straight waveguides are perpendicular to the projection direction and connected to the L a The input waveguide segments intersect vertically, thus obtaining a double-arm heterogeneous MZ optical waveguide structure layer, which is finally connected to an optical fiber and an optical power meter for testing.

[0029] According to a polymer silicon dioxide heterogeneous modulation arm MZ optical waveguide temperature sensor provided by the present invention, the two MZ structures of the MZ pattern photolithography plate include:

[0030] The length L of the input and output area (a) a A straight waveguide of 0.02 to 5 mm;

[0031] The length L of the input and output Y branch region (b) b , which is the length of the Y branch region along the waveguide propagation direction.

[0032] According to the MZ optical waveguide temperature sensor of a polymer silica heterogeneous modulation arm provided by the present invention, in the MZ optical waveguide structure layer, the spacing x6 between two branch arms is 10 to 60 μm, and the curvature radius R is ensured to be 3500 to 7000 μm, which is expressed as the following formula:

[0033]

[0034] Among them, section (c) is the other arm of the waveguide, and its length is L c The length of the two sections (d) is 1000 to 30000 μm, and the two sections (d) are parallel regions, where one side of the photolithography plate is parallel to and fits the waveguide, and the length L d 5~500μm;

[0035] Among them, (e) is the coupling section, the starting section of which starts from one end of (d) and the extension in the z direction is L e The distance is 50 to 1000 μm, and the offset in the x direction is x2, so that the end point is completely aligned with the straight waveguide;

[0036] Among them, the constraint formula is L e ≥2(L d +L e ) and (L a +L b +L c )≤L1, and finally the output waveguide (a).

[0037] It can be seen that compared with the prior art, the present invention has the following beneficial effects:

[0038] Low loss: Compared with the direct docking coupling method, the optical field leakage loss of the present invention is lower.

[0039] Simple process and low cost: Compared with the MZ temperature sensor integration method of combining a multi-layer method with grayscale lithography, the present invention uses direct lithography patterns instead of grayscale lithography and polishing, and its process is simpler and faster, and the cost is also lower.

[0040] High sensing accuracy: Compared with the traditional asymmetric MZ with two arms made of the same material, the two arms of the present invention are made of different materials. Under the same size, the phase difference of the two arms of the MZ optical waveguide changes in opposite directions, and the sensing accuracy of the temperature sensor is higher.

[0041] High sensitivity: Due to the significant difference in the thermo-optic coefficients of polymer waveguides and silica waveguides, when the ambient temperature changes, the light phase changes in the opposite direction. This phase difference will be converted into a significant change in light intensity at the output end of the MZ interferometer. This mechanism makes the sensor very sensitive to temperature changes and can achieve high-precision temperature measurement.

[0042] Wide temperature range measurement: Polymer materials generally have a large thermo-optical coefficient, which enables the sensor to maintain high sensitivity over a wide temperature range. At the same time, the stability of silicon dioxide ensures the long-term reliability of the sensor in high or low temperature environments.

[0043] Simple structure and easy integration: The sensor adopts a three-layer membrane structure substrate chip and builds an MZ optical waveguide structure layer on it. This design not only simplifies the manufacturing process, but also makes the sensor easy to integrate with other optical components or systems, making it easy to use in complex optical systems.

[0044] Good compatibility and stability: The base layer can be silicon or silicon dioxide. These materials have a wide range of applications in the semiconductor and optical fields, so the sensor has great advantages in material selection and process compatibility. At the same time, the chemical stability and mechanical strength of silicon dioxide ensure the stability and durability of the sensor in harsh environments.

[0045] Cost-effectiveness: Although polymer materials may be costly in some aspects, overall the sensor is cost-effective due to its simple structure and ease of manufacturing, coupled with the growing demand for high-precision temperature measurement.

[0046] Potential for application in multiple fields: Due to its high sensitivity and wide temperature range measurement characteristics, this sensor has broad application potential in multiple fields such as communications, medical treatment, industrial control, environmental monitoring, etc., especially in situations where precise temperature control is required, such as temperature compensation in fiber-optic communication systems and temperature monitoring in biomedicine.

[0047] In summary, the MZ optical waveguide temperature sensor with polymer silica heterogeneous modulation arm proposed in this application shows significant advantages in low loss, simple process, low cost, high sensing accuracy, sensitivity, temperature range, integration, stability, cost-effectiveness and application potential.

[0048] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a first structural schematic diagram of a substrate chip with a three-layer membrane structure in an embodiment of an MZ optical waveguide temperature sensor of a polymer silicon dioxide heterogeneous modulation arm of the present invention.

[0050] Figure 2 This is a second structural schematic diagram of a substrate chip with a three-layer membrane structure in an embodiment of an MZ optical waveguide temperature sensor of a polymer silicon dioxide heterogeneous modulation arm of the present invention.

[0051] Figure 3 It is a structural schematic diagram of a mask layer and a photoresist film layer in an embodiment of an MZ optical waveguide temperature sensor of a polymer silicon dioxide heterogeneous modulation arm of the present invention.

[0052] Figure 4 It is a structural schematic diagram of a mask layer and a photolithography plate in an embodiment of an MZ optical waveguide temperature sensor of a polymer silicon dioxide heterogeneous modulation arm of the present invention.

[0053] Figure 5 It is a structural schematic diagram of a photoresist mask layer in an embodiment of an MZ optical waveguide temperature sensor of a polymer silicon dioxide heterogeneous modulation arm of the present invention.

[0054] Figure 6 It is a structural schematic diagram of a mask layer in an embodiment of an MZ optical waveguide temperature sensor of a polymer silicon dioxide heterogeneous modulation arm of the present invention.

[0055] Figure 7 It is a structural schematic diagram of the core layer in an embodiment of an MZ optical waveguide temperature sensor of a polymer silica heterogeneous modulation arm of the present invention.

[0056] Figure 8 It is a schematic structural diagram of a silicon dioxide chip in an embodiment of an MZ optical waveguide temperature sensor of a polymer silicon dioxide heterogeneous modulation arm of the present invention.

[0057] Fig. 9 It is a first structural schematic diagram of a waveguide core material in an embodiment of an MZ optical waveguide temperature sensor of a polymer silica heterogeneous modulation arm of the present invention.

[0058] Fig.10 It is a second structural schematic diagram of the waveguide core material in an embodiment of an MZ optical waveguide temperature sensor of a polymer silica heterogeneous modulation arm of the present invention.

[0059] Fig.11 It is a structural schematic diagram of an MZ pattern photolithography plate in an embodiment of an MZ optical waveguide temperature sensor of a polymer silicon dioxide heterogeneous modulation arm of the present invention.

[0060] Fig.12 It is a principle schematic diagram of an MZ pattern photolithography plate in an embodiment of an MZ optical waveguide temperature sensor of a polymer silicon dioxide heterogeneous modulation arm of the present invention.

[0061] Fig.13 It is a schematic structural diagram of a polymer MZ waveguide in an embodiment of an MZ optical waveguide temperature sensor of a polymer silicon dioxide heterogeneous modulation arm of the present invention.

[0062] Fig.14 It is a schematic structural diagram of the cladding in an embodiment of an MZ optical waveguide temperature sensor of a polymer silica heterogeneous modulation arm of the present invention. DETAILED DESCRIPTION

[0063] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] The present embodiment provides a polymer silicon dioxide heterogeneous modulation arm MZ optical waveguide temperature sensor 100, comprising:

[0065] A substrate chip having a three-layer film structure (the thickness of the substrate chip is 100 to 1000 μm, the length L1 is 1 to 5 cm, and the width x1 is 0.5 to 2 cm), which includes from top to bottom:

[0066] The first silicon dioxide layer 3 with a high refractive index has a refractive index of 1.455 to 1.48.

[0067] The second silicon dioxide layer 2 with a low refractive index has a refractive index of 1.44 to 1.45.

[0068] The base layer 1 is a single crystal silicon layer or a low refractive index silicon dioxide layer.

[0069] An MZ optical waveguide structure layer is formed on the second silicon dioxide layer 2 with a low refractive index. The MZ optical waveguide structure layer includes two branch arms, one of which is a polymer waveguide and the other is a silicon dioxide waveguide. Both branch arms are located on the same plane.

[0070] In the MZ optical waveguide structure layer, light is divided into two paths at its input end, propagating along two branch arms respectively, and then reunited at its output end; among them, due to the different thermo-optic coefficients of the polymer waveguide and the silica waveguide, when the temperature changes, the optical phase changes in the polymer waveguide and the silica waveguide are in opposite directions, which manifests as a significant change in light intensity at the output end of the MZ optical waveguide structure layer, thereby achieving highly sensitive detection of temperature changes.

[0071] In this embodiment, if Figure 1 and 2 As shown, from top to bottom of the substrate chip, the topmost layer is high-refractive-index doped (Ge) silicon dioxide with a refractive index of 1.455 to 1.48 and a thickness of d3 (2 to 10 μm); the second layer is low-refractive-index silicon dioxide with a refractive index of 1.44 to 1.45 and a thickness of d2 (3 to 15 μm); the third layer is silicon or silicon dioxide with a thickness of 100 to 1000 μm.

[0072] In this embodiment, the thickness d3 of the first silicon dioxide layer 3 is 2-8 μm, the thickness d2 of the second silicon dioxide layer 2 is 3-10 μm, and the thickness d1 of the base layer 1 is 100-1000 μm.

[0073] In this embodiment, the thickness d1 of the base layer 1 is preferably 200 μm, the thickness d2 of the second silicon dioxide layer 2 is preferably 6 μm, and the thickness d3 of the first silicon dioxide layer 3 is preferably 5 μm.

[0074] In this embodiment, the steps of preparing the polymer waveguide and the silicon dioxide waveguide include:

[0075] Providing a first silicon dioxide layer 3 to manufacture a silicon dioxide waveguide portion of an MZ optical waveguide structure layer;

[0076] A substrate chip with a three-layer membrane structure that is projected as a rectangle in the vertical direction is selected.

[0077] A mask layer 4 is evaporated on the substrate chip to make a mask layer for the silicon dioxide waveguide; wherein the mask layer 4 can be made of Al, Cr or silicon nitride material, and the thickness d4 is 10-200 nm.

[0078] Spin-coat the photoresist to form a photoresist film layer 5 (such as BP212, AZ photoresist, etc.) with a thickness of 0.1 to 5 μm, a spin-coating speed of 1000 to 10000 rpm, and a time of 30 to 300 seconds. Figure 3 and Figure 4shown.

[0079] A pattern is introduced on the photoresist film layer 5 by using a photolithography plate or a maskless photolithography machine for photolithography and then developed to obtain a photoresist mask layer 10, the structure of which is as follows: Figure 6 As shown. Among them, the photolithography plate is a straight waveguide pattern, such as Figure 5 As shown, the waveguide length L2 is a rectangle of 10100 to 50100 μm, and the waveguide structure width x2 is 3 to 10 μm (the straight waveguide is the opaque part, or the two sides are the exposure areas during maskless lithography). The long side of the waveguide is parallel to the long side of the wafer structure, and the distance between the long side of the waveguide and the long side of the wafer in the x direction is 2 to 50 μm. It intersects the two short sides perpendicularly in the z direction, that is, the length in the z direction is greater than the length of the long side of the wafer.

[0080] In this embodiment, when manufacturing the silicon dioxide waveguide chip, the mask layer 4 is etched with a mask etching agent to obtain a waveguide mask pattern 11, such as Figure 7 shown.

[0081] The waveguide core layer 12 is obtained by plasma etching or ICP etching, and the etching depth is d3, such as Figure 8 shown.

[0082] The photoresist mask layer 10 is removed with a corresponding photoresist developer, and the waveguide mask pattern 11 is removed with a corresponding solution to obtain a silicon dioxide waveguide chip. Fig. 9 shown.

[0083] In this embodiment, the waveguide core material is spin-coated on the silicon dioxide waveguide chip, such as Fig.10 The spin coating speed is 2500-10000 rpm, the spin coating time is 30-300 s, and after curing (curing can be performed in an oven or a hot plate, the curing temperature is 50-70° C., 5-15 min, 85-95° C., 5-30 min), a polymer waveguide core layer material film 13 is obtained, as shown. Fig.11 As shown, the film thickness d6 is 2 to 8 μm, which is equal to the thickness of the waveguide d3.

[0084] Using MZ pattern photolithography, such as Fig.12 As shown, photolithography is performed or a maskless photolithography machine is used to import a graphic file consistent with the MZ pattern photolithography plate (in gds format), and then the polymer waveguide 15 is obtained after development, thereby forming an MZ optical waveguide structure, such as Fig.14 shown.

[0085] In this embodiment, a polymer cladding is spin-coated on the MZ optical waveguide structure (spinning speed 2500-10000 rpm, spin coating time 30-300 s, and cured by a desired curing method), and the cladding thickness d7 is 1.5-5 μm thicker than d6.

[0086] In this embodiment, a dicing machine or a blade is used to directly cut the MZ optical waveguide structure after the cladding, and the projection direction is perpendicular to the input and output straight waveguides and connected to the L a The input waveguide segments intersect vertically, and the double-arm heterogeneous MZ optical waveguide structure layer is obtained. Finally, the optical fiber is connected to the optical power meter for testing to verify the feasibility of the result.

[0087] In this embodiment, if Fig.13 As shown, the two MZ structures of the MZ pattern reticle include:

[0088] The length L of the input and output area (a) a A straight waveguide of 0.02 to 5 mm;

[0089] The length L of the input and output Y branch region (b) b , which is the length of the Y branch region along the waveguide propagation direction, where the branch graph is a cosine structure. Because the transmission loss and bending loss of the cosine-shaped function curve waveguide are low, the curve equation is: The parameters a and b are defined by the branch angle θ and the branch distance d (d = 2 × x5). The branch angle θ is less than 1 degree, and θ is affected by the offset x6 in the x direction and the offset L in the z direction. b Determine, the formula is:

[0090] In this embodiment, in the MZ optical waveguide structure layer, the interval x6 between the two branch arms is 10-60 μm, and the curvature radius R is ensured to be 3500-7000 μm, which is expressed as the following formula to reduce the bending loss of the device:

[0091]

[0092] Among them, section (c) is the other arm of the waveguide, and its length is L c The length of the two sections (d) is 1000 to 30000 μm, and the two sections (d) are parallel regions, where one side of the photolithography plate is parallel to and fits the waveguide, and the length L d 5~500μm;

[0093] Among them, (e) is the coupling section, the starting section of which starts from one end of (d) and the extension in the z direction is L e The distance is 50 to 1000 μm, and the offset in the x direction is x2, so that the end point is completely aligned with the straight waveguide;

[0094] Among them, the constraint formula is L e ≥2(L d +L e ) and (L a +L b +L c )≤L1, and finally the output waveguide (a).

[0095] In practical applications, a commercial (Rui Xin Yuan) three-layer membrane structure substrate sheet with a rectangular projection in the vertical direction is first selected (the substrate sheet thickness is 693 μm, its length L1 is 3 cm, and its width x1 is 2 cm), such as Figure 1 and 2 As shown. The three-layer film structure is from top to bottom. The top layer is high-refractive-index doped (Ge) silicon dioxide, with a refractive index of 1.48 and a thickness of d1 (3 μm). The second layer is low-refractive-index silicon dioxide, with a refractive index of 1.445 and a thickness of d2 (15 μm). The third layer is silicon or silicon dioxide with a thickness of 675 μm.

[0096] Evaporate a mask layer 4 (here the mask layer material can be Al, with a thickness of 42 nm) on the wafer, spin-coat a photoresist, and form a photoresist film layer 5. Use SU-8 series 2002 model photoresist with a thickness of 1.5 μm, spin-coat at 3000 rpm, and for 30 seconds. The mask photoresist structure is as follows: Figure 2 shown.

[0097] A photolithography plate and a photolithography machine, or a maskless photolithography machine is used to import a pattern for photolithography. The photolithography plate of this embodiment is a straight waveguide pattern, the waveguide length L2 is a rectangle of 30100 μm, and the waveguide structure width x2 is 3 μm. The long side of the waveguide is parallel to the long side of the wafer structure, and the distance between the long side of the waveguide and the long side of the wafer in the x direction is 50 μm. In the z direction, it intersects perpendicularly with the two short sides, that is, the length in the z direction is greater than the length of the long side of the wafer.

[0098] After photolithography (photolithography exposure intensity 20mW / cm2, time 8s) and development (development in a developer corresponding to the photoresist, time: 30s, and then rinsed with isopropyl alcohol and deionized water) to obtain a photoresist mask layer 10, the structure of which is as follows Figure 6 The mask layer 4 is etched with a mask etching reagent (developed with a sodium hydroxide aqueous solution having a mass ratio of 0.5%) to obtain a waveguide mask pattern 11, as shown in FIG. Figure 7 The waveguide core layer 12 is obtained by ICP etching, and the etching depth is d3, as shown in FIG. Figure 8 The photoresist mask layer 10 is removed with a corresponding photoresist developer, and the waveguide mask pattern 11 is removed with a strong sodium oxide aqueous solution with a mass ratio of 5% (development time 5s), to obtain a silicon dioxide waveguide chip, as shown. Fig. 9 shown.

[0099] The waveguide core material is spin-coated on a silicon dioxide chip, which shows a three-dimensional schematic diagram. Fig.10 The spin coating speed is 5000 pm, the spin coating time is 60 s, and after curing (curing can be performed in an oven or a hot plate, the curing temperature is 60° C., 5 min, 90° C., 10 min), a polymer waveguide core layer material film 13 is obtained, as shown. Fig.11 As shown, the film thickness d6 is 3 μm, which is equal to the waveguide thickness. (Here, it can be SU-8 material) Using MZ pattern photolithography plate 14, as shown Fig.11 Perform photolithography or use a maskless photolithography machine to import the above-mentioned photolithography plate consistent (GDS format) graphic file.

[0100] like Fig.12 and 13 As shown, both M-Z structures are divided into: input and output area (a) length L a The straight waveguide is 4 mm long; the length of the input and output Y branch region (b) is L b =100μm. Among them, the branch pattern is a cosine structure, because the transmission loss and bending loss of the cosine-shaped function curve waveguide are low, and the curve equation is: The parameters a and b are defined by the branch angle θ and the branch distance d (d = 2 × x5). The branch angle θ is less than 1 degree, and θ is affected by the offset x6 in the x direction and the offset L in the z direction. b Determine, the formula is:

[0101] The distance x6 between the two branch arms is 50 μm. The radius of curvature R is 5000 μm to reduce the bending loss of the device. (c) is the other arm of the waveguide, and its length is L c The two sections (d) are parallel regions, one side of the photoresist is parallel to the waveguide and fits in place, and the length is L d (e) is the coupling section, the starting section of which starts from one end of (d) and the extension in the z direction is L e The length of the waveguide is 500 μm, and the offset in the x direction is x2, so that the end point is completely aligned with the straight waveguide. The constraint formula is L e ≥2(L d +L e ) and (L a +L b +L c )≤L1, and finally the output waveguide (a).

[0102] In summary, compared with the direct docking coupling method, the optical field leakage loss of the present invention is lower. Compared with the MZ temperature sensor integration method combining multi-layer method with grayscale lithography, the present invention uses direct lithography patterning instead of grayscale lithography and polishing, and its process is simpler and faster, and the cost is also lower. Compared with the traditional asymmetric MZ with the same material in both arms, the two arms of the present invention are made of different materials. Under the same size, the phase difference of the two arms of the MZ optical waveguide changes in opposite directions, and the sensing accuracy of its temperature sensor is higher.

[0103] Due to the significant difference in the thermo-optic coefficients of polymer waveguides and silica waveguides, when the ambient temperature changes, the optical phase changes in the opposite direction. This phase difference will be converted into a significant change in light intensity at the output end of the MZ interferometer. This mechanism makes the sensor very sensitive to temperature changes and can achieve high-precision temperature measurement.

[0104] Polymer materials usually have a large thermo-optical coefficient, which enables the sensor to maintain a high sensitivity over a wide temperature range. At the same time, the stability of silicon dioxide ensures the long-term reliability of the sensor in high or low temperature environments. The sensor of the present invention adopts a substrate chip with a three-layer membrane structure, and constructs an MZ optical waveguide structure layer thereon. This design not only simplifies the manufacturing process, but also makes the sensor easy to integrate with other optical elements or systems, and is convenient for application in complex optical systems. The base layer can be selected from silicon or silicon dioxide layers. These materials have a wide application base in the semiconductor and optical fields, so the sensor has great advantages in material selection and process compatibility. At the same time, the chemical stability and mechanical strength of silicon dioxide ensure the stability and durability of the sensor in harsh environments.

[0105] Although polymer materials may be more expensive in some aspects, overall, the sensor is cost-effective due to its simple structure and ease of manufacture, coupled with the growing demand for high-precision temperature measurement. Due to its high sensitivity and wide temperature range measurement characteristics, the sensor has broad application potential in many fields such as communications, medical treatment, industrial control, and environmental monitoring, especially in situations where precise temperature control is required, such as temperature compensation in optical fiber communication systems and temperature monitoring in biomedicine.

[0106] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A polymer-silicon dioxide heterogeneous modulator arm MZ optical waveguide temperature sensor, characterized in that: include: The substrate chip has a three-layer film structure, which includes, from top to bottom: A first high-refractive-index silicon dioxide layer, whose refractive index is 1.455 to 1.48; A second low-refractive-index silicon dioxide layer, whose refractive index is 1.44 to 1.45; A base layer, wherein the base layer is a single crystal silicon layer or a low refractive index silicon dioxide layer; An MZ optical waveguide structure layer is formed on the second silicon dioxide layer with a low refractive index, and includes two branch arms, one of which is a polymer waveguide and the other is a silicon dioxide waveguide, and the two branch arms are located on the same plane; In the MZ optical waveguide structure layer, light is divided into two paths at its input end, propagating along two branch arms respectively, and then reunited at its output end; wherein, due to the different thermo-optic coefficients of the polymer waveguide and the silica waveguide, when the temperature changes, the optical phases of the polymer waveguide and the silica waveguide change in opposite directions, which manifests as a significant change in light intensity at the output end of the MZ optical waveguide structure layer, thereby achieving highly sensitive detection of temperature changes.

2. The sensor according to claim 1, characterized in that: The thickness of the first silicon dioxide layer is 2-8 μm, the thickness of the second silicon dioxide layer is 3-10 μm, and the thickness of the base layer is 100-1000 μm.

3. The sensor according to claim 1, characterized in that The steps of preparing the polymer waveguide and the silica waveguide include: Providing a first silicon dioxide layer with a high refractive index to manufacture a silicon dioxide waveguide portion of an MZ optical waveguide structure layer; A substrate chip having a three-layer membrane structure and a rectangular shape in vertical projection is selected; Evaporating a mask layer on a substrate chip to form a mask layer for a silicon dioxide waveguide; Spin-coating photoresist to form a photoresist film layer with a thickness of 0.1 to 5 μm; A photoresist mask layer is obtained by introducing a pattern on the photoresist film layer using a photolithography plate or a maskless photolithography machine, performing photolithography and then developing the pattern.

4. The sensor according to claim 3, characterized in that: When manufacturing a silicon dioxide waveguide, a mask etching agent is used to etch the mask layer to obtain a waveguide mask pattern; The waveguide core layer is obtained by plasma etching or ICP etching, and the etching depth is d3; The photoresist mask layer is removed with a corresponding photoresist developer, and the waveguide mask pattern is removed with a corresponding solution to obtain a silicon dioxide waveguide chip.

5. The sensor according to claim 4, characterized in that: Spin coating a waveguide core material on a silicon dioxide waveguide chip to obtain a polymer waveguide core material film, wherein the film thickness d6 is 1 to 10 μm, which is equal to the thickness of the waveguide d3; An MZ pattern photoresist is used to perform photolithography or a maskless photolithography machine is used to import a graphic file consistent with the MZ pattern photoresist, and a polymer waveguide is obtained after development, thereby forming an MZ optical waveguide structure.

6. The sensor according to claim 5, characterized in that: A polymer cladding is spin-coated on the MZ optical waveguide structure, and the thickness d7 of the cladding is 1.5 to 5 μm thicker than d6.

7. The sensor according to claim 6, characterized in that: The MZ optical waveguide structure behind the cladding is directly cut, perpendicular to the input and output straight waveguides along the projection direction and connected to L a The input waveguide segments intersect vertically, thus obtaining a double-arm heterogeneous MZ optical waveguide structure layer, which is finally connected to an optical fiber and an optical power meter for testing.

8. The sensor according to claim 5, characterized in that: The two MZ structures of the MZ pattern reticle include: The length L of the input and output area (a) a A straight waveguide of 0.02 to 5 mm; The length L of the input and output Y branch region (b) b , which is the length of the Y branch region along the waveguide propagation direction.

9. The sensor according to claim 8, characterized in that: In the MZ optical waveguide structure layer, the distance x6 between the two branch arms is 10 to 60 μm, and the curvature radius R is ensured to be 3500 to 7000 μm, which is expressed as the following formula: Among them, section (c) is the other arm of the waveguide, and its length is L c The length of the two sections (d) is 1000 to 30000 μm, and the two sections (d) are parallel regions, where one side of the photolithography plate is parallel to and fits the waveguide, and the length L d 5~500μm; Among them, (e) is the coupling section, the starting section of which starts from one end of (d) and the extension in the z direction is L e The distance is 50 to 1000 μm, and the offset in the x direction is x2, so that the end point is completely aligned with the straight waveguide; Among them, the constraint formula is L e ≥2(L d +L e ) and (L a +L b +L c )≤L1, and finally the output waveguide (a).

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