CN110635021B - Femtosecond laser direct-writing waveguide coupling superconducting nanowire single photon detector - Google Patents
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- 229910001218 Gallium arsenide Inorganic materials 0.000 description 2
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J1/44—Electric circuits
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N60/00—Superconducting devices
- H10N60/01—Manufacture or treatment
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N60/00—Superconducting devices
- H10N60/80—Constructional details
- H10N60/84—Switching means for devices switchable between superconducting and normal states
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J1/44—Electric circuits
- G01J2001/4413—Type
- G01J2001/442—Single-photon detection or photon counting
Abstract
The invention provides a femtosecond laser direct-writing waveguide coupling superconducting nanowire single-photon detector and a preparation method thereof, wherein the femtosecond laser direct-writing waveguide coupling superconducting nanowire single-photon detector comprises: a silicon dioxide substrate; the optical waveguide is positioned in the silicon dioxide substrate, one end face of the optical waveguide is flush with one side face of the silicon dioxide substrate, and the other end face of the optical waveguide extends to the upper surface of the silicon dioxide substrate; the optical waveguide is formed based on a femtosecond laser direct writing process; and the superconducting nanowire is positioned on the upper surface of the silicon dioxide substrate and positioned on the end face of the optical waveguide extending to the upper surface of the silicon dioxide substrate. The femtosecond laser direct-writing waveguide coupling superconducting nanowire single-photon detector is formed in the silicon dioxide substrate through a femtosecond laser direct-writing process, the preparation process is simple, and the integration level of devices is high; the material of the optical waveguide in the femtosecond laser direct-writing waveguide coupling superconducting nanowire single photon detector is similar to that of the optical fiber, and the coupling efficiency is high.
Description
Technical Field
The invention relates to the technical field of detectors, in particular to a femtosecond laser direct-writing waveguide coupling superconducting nanowire single-photon detector and a preparation method thereof.
Background
Superconducting nanoparticlesA linear Single-Photon Detector (SNSPD) has attracted much attention in recent years because of its excellent characteristics in detection efficiency, dark count rate, time jitter, count rate, and the like. The commonly used SNSPD optical coupling modes comprise optical fiber vertical coupling and optical waveguide coupling, wherein the optical waveguide coupling has the advantages of high efficiency, rapidness, easy realization of on-chip integration and the like, and has wide requirements on quantum optical experiments and application thereof. However, most of the optical waveguides in the conventional superconducting nanowire single photon detector are made of Si (silicon), GaAs (gallium arsenide), GaN (gallium nitride), etc., and most of the optical fibers are made of SiO (silicon oxide)2(silicon dioxide), the refractive index of the optical waveguide is greatly different from that of the optical fiber, the coupling efficiency between the optical fiber and the optical waveguide is poor, the conventional SNSPD coupling is only suitable for on-chip detection at present, and the application expansion of a waveguide device is limited; meanwhile, the existing optical waveguide is generally prepared on the surface of a silicon dioxide substrate through a micro-nano processing technology, and the preparation technology is complex.
Disclosure of Invention
In view of the above disadvantages of the prior art, the present invention aims to provide a femtosecond laser direct-writing waveguide-coupled superconducting nanowire single photon detector and a manufacturing method thereof, which are used for solving the problems of poor coupling efficiency between an optical fiber and an optical waveguide and complicated manufacturing process of the optical waveguide of the superconducting nanowire single photon detector in the prior art.
In order to achieve the above objects and other related objects, the present invention provides a femtosecond laser direct-write waveguide coupled superconducting nanowire single photon detector, including:
a silicon dioxide substrate;
the optical waveguide is positioned in the silicon dioxide substrate, one end face of the optical waveguide is flush with one side face of the silicon dioxide substrate, and the other end face of the optical waveguide extends to the upper surface of the silicon dioxide substrate; the optical waveguide is formed on the basis of a femtosecond laser direct writing process, and the refractive index of the optical waveguide is slightly higher than that of the silicon dioxide substrate;
and the superconducting nanowire is positioned on the upper surface of the silicon dioxide substrate and positioned on the end face of the optical waveguide extending to the upper surface of the silicon dioxide substrate.
Optionally, the optical waveguide comprises:
the horizontal part is positioned in the silicon dioxide substrate, is parallel to the surface of the substrate and has a distance with the upper surface of the silicon dioxide substrate; one end surface of the horizontal part is flush with one side surface of the silicon dioxide substrate;
and the inclined part is positioned in the silicon dioxide substrate, one end surface of the inclined part is integrally connected with the horizontal part, and the other end surface of the inclined part extends to the upper surface of the silicon dioxide substrate.
Optionally, an orthographic projection of the inclined part on the plane of the horizontal part is located on an extension line of the horizontal part.
Optionally, the included angle between the inclined part and the surface of the silicon dioxide substrate comprises 7-9 degrees.
Optionally, the number of the optical waveguides is multiple, and the multiple optical waveguides are arranged in parallel at intervals; the number of the superconducting nanowires is multiple, and the plurality of superconducting nanowires and the plurality of optical waveguides are arranged in one-to-one correspondence.
Optionally, the femtosecond laser direct-write waveguide coupled superconducting nanowire single photon detector further includes:
the V-shaped groove structure is attached to the side face of the silicon dioxide substrate, which is exposed out of the optical waveguide;
and the optical fiber is positioned in the V-shaped groove structure, and the output end of the optical fiber is coupled with the end face of one side face of the silicon dioxide substrate, which is flush with the optical waveguide.
Optionally, the femtosecond laser direct-writing waveguide coupled superconducting nanowire single photon detector further comprises an optical adhesive, and the optical adhesive is located between the V-shaped groove structure and the silicon dioxide substrate.
In order to achieve the above objects and other related objects, the present invention further provides a method for preparing a femtosecond laser direct-writing waveguide coupled superconducting nanowire single photon detector, wherein the method for preparing the femtosecond laser direct-writing waveguide coupled superconducting nanowire single photon detector comprises the following steps:
providing a silicon dioxide substrate, and forming an optical waveguide in the silicon dioxide substrate by adopting a femtosecond laser direct writing process, wherein one end face of the optical waveguide is flush with one side face of the silicon dioxide substrate, and the other end face of the optical waveguide extends to the upper surface of the silicon dioxide substrate;
and forming a superconducting nanowire on the upper surface of the silicon dioxide substrate, wherein the superconducting nanowire is positioned on the end surface of the optical waveguide extending to the upper surface of the silicon dioxide substrate.
Optionally, forming a plurality of optical waveguides in the silicon dioxide substrate by using a femtosecond laser direct writing process, wherein the plurality of optical waveguides are arranged in parallel at intervals; and forming a plurality of superconducting nanowires on the upper surface of the silicon dioxide substrate, wherein the plurality of superconducting nanowires and the plurality of optical waveguides are arranged in one-to-one correspondence.
Optionally, after the superconducting nanowire is formed on the upper surface of the silicon dioxide substrate, the method further includes the following steps:
providing a V-shaped groove structure, wherein an optical fiber is arranged in the V-shaped groove structure;
and pasting the V-shaped groove structure on the side surface of the silicon dioxide substrate exposed out of the optical waveguide, and enabling the output end of the optical fiber to be flush with the optical waveguide and coupled with the end surface of one side surface of the silicon dioxide substrate.
Optionally, the V-groove structure is attached to the side surface of the silicon dioxide substrate, where the optical waveguide is exposed, by using optical cement.
As mentioned above, the femtosecond laser direct-writing waveguide coupling superconducting nanowire single photon detector and the preparation method thereof have the following beneficial effects: the femtosecond laser direct-writing waveguide coupling superconducting nanowire single-photon detector is formed in the silicon dioxide substrate through a femtosecond laser direct-writing process, the preparation process is simple, and the integration level of devices is high; the material of the optical waveguide in the femtosecond laser direct-writing waveguide coupling superconducting nanowire single photon detector is similar to that of the optical fiber, and the coupling efficiency is high.
Drawings
Fig. 1 is a schematic perspective view of a femtosecond laser direct-write waveguide coupled superconducting nanowire single photon detector according to an embodiment of the present invention.
Fig. 2 shows an enlarged view of the area a in fig. 1.
Fig. 3 is a front view of a V-shaped groove structure in a femtosecond laser direct-write waveguide coupled superconducting nanowire single photon detector according to an embodiment of the present invention.
Fig. 4 is a flowchart illustrating a method for manufacturing a femtosecond laser direct-write waveguide coupled superconducting nanowire single photon detector according to a second embodiment of the present invention.
Description of the element reference numerals
1 silicon dioxide substrate
2 optical waveguide
21 horizontal part
22 inclined part
3 superconducting nanowires
4 optical fiber
5V type groove structure
Angle between the alpha-slope portion and the surface of the silicon dioxide substrate
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Please refer to fig. 1 to 4. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and although the drawings only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation, the form, quantity and proportion of the components in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.
Example one
Referring to fig. 1 and 2, the invention provides a femtosecond laser direct-writing waveguide coupled superconducting nanowire single photon detector, which includes: a silicon dioxide substrate 1; the optical waveguide 2 is positioned in the silicon dioxide substrate 1, one end face of the optical waveguide 2 is flush with one side face of the silicon dioxide substrate 1, and the other end face of the optical waveguide extends to the upper surface of the silicon dioxide substrate 1; the optical waveguide 2 is formed based on a femtosecond laser direct writing process; and the superconducting nanowire 3 is positioned on the upper surface of the silicon dioxide substrate 1, and the superconducting nanowire 3 is positioned on the end surface of the optical waveguide 2 extending to the upper surface of the silicon dioxide substrate 1. The femtosecond laser direct-writing waveguide coupling superconducting nanowire single photon detector is formed in the silicon dioxide substrate 1 through a femtosecond laser direct-writing process, and the preparation process is simple because the femtosecond laser direct-writing is completed in one step; meanwhile, because the facula of the femtosecond laser is smaller, the waveguide (about several mum) with extremely small diameter can be prepared, so that the integration level of the device is high; one end of the optical waveguide 2 is flush with one side surface of the silicon dioxide substrate 1, and the other end surface of the optical waveguide extends to the upper surface of the silicon dioxide substrate 1, so that the optical waveguide 2 can be attached to a V-shaped groove structure through the side wall of the silicon dioxide substrate 1 by adopting the existing mature process, and the superconducting nanowire 3 can be prepared on the end surface of the optical waveguide 2 extending to the upper surface of the silicon dioxide substrate 1 by adopting the mature process due to the higher flatness of the upper surface of the silicon dioxide substrate 1, so that the quality of the prepared superconducting nanowire 3 can be ensured; meanwhile, the length of the optical waveguide 2 can be ensured, and enough space can be reserved between external input light and a detection end (the superconducting nanowire 3) so as to prepare a complex optical waveguide coupling structure in the future and meet the requirement of on-chip quantum optical test.
As an example, the shape of the silicon dioxide substrate 1 may include a cube or a rectangular parallelepiped, or the like. The side length and thickness of the silicon dioxide substrate 1 depend on the capability of the process line, for example, the side length of the silicon dioxide substrate 1 may include, but is not limited to, 20mm, and the thickness of the silicon dioxide substrate 1 may include, but is not limited to, 1 mm. In other examples, the side length and the thickness of the silicon dioxide substrate 1 can be set to other values according to actual needs.
As an example, the optical waveguide 2 may include: a horizontal part 21, wherein the horizontal part 21 is positioned in the silicon dioxide substrate 1, the horizontal part 21 is parallel to the surface of the silicon dioxide substrate 1, and the horizontal part 21 is spaced from the upper surface of the silicon dioxide substrate 1; one end surface of the horizontal part 21 is flush with one side surface of the silicon dioxide substrate 1; and an inclined part 22, wherein the inclined part 22 is located in the silicon dioxide substrate, one end surface of the inclined part 22 is integrally connected with the horizontal part 21, and the other end surface extends to the upper surface of the silicon dioxide substrate 1. Specifically, the horizontal portion 21 may have a distance from both the upper surface of the silicon dioxide substrate 1 and the lower surface of the silicon dioxide substrate 1.
As an example, the orthographic projection of the inclined portion 22 on the plane of the horizontal portion 21 is located on the extension line of the horizontal portion 21, that is, the inclined portion 22 is not inclined to both sides of the horizontal portion 21 except that it is inclined to an upper side of an incline away from the horizontal portion 21 compared to the horizontal portion 21.
As an example, an included angle α between the inclined portion 22 and the surface of the silicon dioxide substrate 1 may be set according to actual needs, and preferably, in this embodiment, the included angle α between the inclined portion 22 and the surface of the silicon dioxide substrate 1 may include 7 to 9 °, that is, the included angle α between the inclined portion 22 and the horizontal portion 21 may include 7 to 9 °.
As an example, the diameter of the optical waveguide 2 may be set according to actual needs, preferably, the diameter of the optical waveguide 2 may include 1 to 10 μm, and more preferably, in this embodiment, the diameter of the optical waveguide 2 may include 6 μm.
As an example, an end surface of the optical waveguide 2 extending to the upper surface of the silicon dioxide substrate 1 may be an elliptical end surface, and a major axis and a minor axis of the elliptical end surface may be set according to actual needs, and preferably, in this embodiment, the major axis of the elliptical end surface may include about 50 μm, and the minor axis of the elliptical end surface may include about 6 μm.
As an example, the number of the optical waveguides 2 is multiple, and the multiple optical waveguides 2 are arranged in parallel at intervals; the number of the superconducting nanowires 3 is multiple, the superconducting nanowires 3 and the optical waveguides 2 are arranged in a one-to-one correspondence manner, that is, one superconducting nanowire 3 is arranged on the end surface of each optical waveguide 2 extending to the upper surface of the silicon dioxide substrate 1.
As an example, the superconducting nanowire 3 may extend in a meandering shape at an end surface of the optical waveguide 2 extending to the upper surface of the silicon dioxide substrate 1, and the superconducting nanowire 3 may include, but is not limited to, a NbN (niobium nitride) superconducting nanowire.
In an example, the femtosecond laser direct-writing waveguide coupled superconducting nanowire single photon detector can further comprise an optical fiber 4, wherein the output end of the optical fiber 4 is coupled with the end face of the optical waveguide 2 flush with one side face of the silicon dioxide substrate 1; the material of the optical waveguide 2 is similar to that of the optical fiber 4, and the material of the optical waveguide 2 is selected to be similar to that of the optical fiber 4, so that the coupling efficiency of the femtosecond laser direct-write waveguide coupling superconducting nanowire single photon detector can be improved.
In another example, the femtosecond laser direct-write waveguide coupled superconducting nanowire single photon detector described with reference to fig. 1 and 3 further includes: the V-shaped groove structure 5 is attached to the side face of the silicon dioxide substrate 1, which is exposed out of the optical waveguide 2; and the optical fiber 4 is positioned in the V-shaped groove structure 5, and the output end of the optical fiber 4 is flush with the optical waveguide 2 and coupled with the end face of one side face of the silicon dioxide substrate 1.
Specifically, the V-groove structure 5 may include any one of the known V-groove structures, such as the one manufactured by OZ Optics, and the specific structure of the V-groove structure 5 is known to those skilled in the art and will not be described herein.
The material of the optical fiber 4 is similar to the material of the optical waveguide 2, and the term "the material of the optical fiber 4 is similar to the material of the optical waveguide 2" means that the main material of the optical fiber 4 is the same as the main material of the optical waveguide 2, and may be silicon dioxide, but at least one of the types and the doping amounts of the doped ions in the optical fiber 4 and the optical waveguide 2 is different, and the refractive index of the optical fiber 4 is slightly different from the refractive index of the optical waveguide 2, and may be different by a few thousandths.
By way of example, the femtosecond laser direct-writing waveguide coupled superconducting nanowire single photon detector further comprises an optical adhesive (not shown), and the optical adhesive is located between the V-shaped groove structure 5 and the silicon dioxide substrate 1.
The optical counting and optical response pulse waveform of the femtosecond laser direct-writing waveguide coupled superconducting nanowire single-photon detector can be equivalent to the optical counting and optical response pulse waveform of the conventional femtosecond laser direct-writing waveguide coupled superconducting nanowire single-photon detector; the time jitter of the femtosecond laser direct-writing waveguide coupling superconducting nanowire single-photon detector can be 40.8ps (picosecond), and is equivalent to that of the conventional superconducting nanowire single-photon detector; the recovery time of the femtosecond laser direct-writing waveguide coupling superconducting nanowire single-photon detector can be 40.8ns (nanosecond), and is equivalent to that of the conventional superconducting nanowire single-photon detector.
Example two
Referring to fig. 4 in conjunction with fig. 1 to 3, the invention further provides a method for manufacturing a femtosecond laser direct-write waveguide coupled superconducting nanowire single photon detector, and the method for manufacturing the femtosecond laser direct-write waveguide coupled superconducting nanowire single photon detector includes the following steps:
1) providing a silicon dioxide substrate, and forming an optical waveguide in the silicon dioxide substrate by adopting a femtosecond laser direct writing process, wherein one end face of the optical waveguide is flush with one side face of the silicon dioxide substrate, and the other end face of the optical waveguide extends to the upper surface of the silicon dioxide substrate;
2) and forming a superconducting nanowire on the upper surface of the silicon dioxide substrate, wherein the superconducting nanowire is positioned on the end surface of the optical waveguide extending to the upper surface of the silicon dioxide substrate.
In step 1), referring to step S1 in fig. 4 and fig. 1 to 2, a silicon dioxide substrate 1 is provided, an optical waveguide 2 is formed in the silicon dioxide substrate 1 by a femtosecond laser direct writing process, one end face of the optical waveguide 2 is flush with one side face of the silicon dioxide substrate 1, and the other end face extends to the upper surface of the silicon dioxide substrate 1.
Specifically, the specific method for forming the optical waveguide 2 in the silicon dioxide substrate 1 by using the femtosecond laser direct writing process is known to those skilled in the art, and will not be described herein again.
As an example, the shape of the silicon dioxide substrate 1 may include a cube or a rectangular parallelepiped, or the like. The side length and thickness of the silicon dioxide substrate 1 depend on the capability of the process line, for example, the side length of the silicon dioxide substrate 1 may include, but is not limited to, 20mm, and the thickness of the silicon dioxide substrate 1 may include, but is not limited to, 1 mm. In other examples, the side length and the thickness of the silicon dioxide substrate 1 can be set to other values according to actual needs.
As an example, the optical waveguide 2 may include: a horizontal part 21, wherein the horizontal part 21 is positioned in the silicon dioxide substrate 1, the horizontal part 21 is parallel to the surface of the silicon dioxide substrate 1, and the horizontal part 21 is spaced from the upper surface of the silicon dioxide substrate 1; one end surface of the horizontal part 21 is flush with one side surface of the silicon dioxide substrate 1; and an inclined part 22, wherein the inclined part 22 is located in the silicon dioxide substrate, one end surface of the inclined part 22 is integrally connected with the horizontal part 21, and the other end surface extends to the upper surface of the silicon dioxide substrate 1. Specifically, the horizontal portion 21 may have a distance from both the upper surface of the silicon dioxide substrate 1 and the lower surface of the silicon dioxide substrate 1.
As an example, the orthographic projection of the inclined portion 22 on the plane of the horizontal portion 21 is located on the extension line of the horizontal portion 21, that is, the inclined portion 22 is not inclined to both sides of the horizontal portion 21 except that it is inclined to an upper side of an incline away from the horizontal portion 21 compared to the horizontal portion 21.
As an example, an included angle α between the inclined portion 22 and the surface of the silicon dioxide substrate 1 may be set according to actual needs, and preferably, in this embodiment, the included angle α between the inclined portion 22 and the surface of the silicon dioxide substrate 1 may include 7 to 9 °, that is, the included angle α between the inclined portion 22 and the horizontal portion 21 may include 7 to 9 °.
As an example, the diameter of the optical waveguide 2 may be set according to actual needs, preferably, the diameter of the optical waveguide 2 may include 1 to 10 μm, and more preferably, in this embodiment, the diameter of the optical waveguide 2 may include 6 μm.
As an example, an end surface of the optical waveguide 2 extending to the upper surface of the silicon dioxide substrate 1 may be an elliptical end surface, and a major axis and a minor axis of the elliptical end surface may be set according to actual needs, and preferably, in this embodiment, the major axis of the elliptical end surface may include about 50 μm, and the minor axis of the elliptical end surface may include about 6 μm.
As an example, the number of the optical waveguides 2 is plural, and the plural optical waveguides 2 are arranged in parallel at intervals.
In step 2), referring to step S2 in fig. 4 and fig. 1 to 2, a superconducting nanowire 3 is formed on the upper surface of the silicon dioxide substrate 1, and the superconducting nanowire 3 is located at an end surface of the optical waveguide 2 extending to the upper surface of the silicon dioxide substrate 1.
As an example, the number of the superconducting nanowires 3 is multiple, and the plurality of superconducting nanowires 3 and the plurality of optical waveguides 2 are arranged in a one-to-one correspondence manner, that is, one superconducting nanowire 3 is arranged on an end surface of each optical waveguide 2 extending to the upper surface of the silicon dioxide substrate 1.
As an example, the superconducting nanowire 3 may extend in a meandering shape at an end surface of the optical waveguide 2 extending to the upper surface of the silicon dioxide substrate 1, and the superconducting nanowire 3 may include, but is not limited to, a NbN (niobium nitride) superconducting nanowire.
As an example, with continuing reference to fig. 1 and fig. 3, after forming the superconducting nanowire 2 on the upper surface of the silicon dioxide substrate 1, the following steps are further included:
3) providing a V-shaped groove structure 5, wherein an optical fiber 4 is arranged in the V-shaped groove structure 5;
4) and the V-shaped groove structure 5 is attached to the side surface of the silicon dioxide substrate 1, which is exposed out of the optical waveguide 2, and the output end of the optical fiber 4 is coupled with the end surface of the optical waveguide 2, which is flush with the side surface of the silicon dioxide substrate 1.
As an example, the V-groove structure 5 may be attached to the side surface of the silicon dioxide substrate 1 where the optical waveguide 2 is exposed by using an optical adhesive.
Specifically, the V-groove structure 5 may include any one of the known V-groove structures, such as the one manufactured by OZ Optics, and the specific structure of the V-groove structure 5 is known to those skilled in the art and will not be described herein.
In summary, the present invention provides a femtosecond laser direct-writing waveguide coupled superconducting nanowire single photon detector and a method for manufacturing the same, wherein the femtosecond laser direct-writing waveguide coupled superconducting nanowire single photon detector includes: a silicon dioxide substrate; the optical waveguide is positioned in the silicon dioxide substrate, one end face of the optical waveguide is flush with one side face of the silicon dioxide substrate, and the other end face of the optical waveguide extends to the upper surface of the silicon dioxide substrate; the optical waveguide is formed on the basis of a femtosecond laser direct writing process, and the refractive index of the optical waveguide is slightly higher than that of the silicon dioxide substrate; and the superconducting nanowire is positioned on the upper surface of the silicon dioxide substrate and positioned on the end face of the optical waveguide extending to the upper surface of the silicon dioxide substrate. The femtosecond laser direct-writing waveguide coupling superconducting nanowire single-photon detector is formed in the silicon dioxide substrate through a femtosecond laser direct-writing process, the preparation process is simple, and the integration level of devices is high; the material of the optical waveguide in the femtosecond laser direct-writing waveguide coupling superconducting nanowire single photon detector is similar to that of the optical fiber, and the coupling efficiency is high.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (12)
1. A femtosecond laser direct-writing waveguide coupling superconducting nanowire single-photon detector is characterized by comprising:
a silicon dioxide substrate;
the optical waveguide is positioned in the silicon dioxide substrate, one end face of the optical waveguide is flush with one side face of the silicon dioxide substrate, and the other end face of the optical waveguide extends to the upper surface of the silicon dioxide substrate; the optical waveguide is formed based on a femtosecond laser direct writing process, and the refractive index is higher than that of the silicon dioxide substrate;
and the superconducting nanowire is positioned on the upper surface of the silicon dioxide substrate and positioned on the end face of the optical waveguide extending to the upper surface of the silicon dioxide substrate.
2. The femtosecond laser direct-write waveguide coupled superconducting nanowire single-photon detector as claimed in claim 1, wherein: the optical waveguide includes:
the horizontal part is positioned in the silicon dioxide substrate, is parallel to the surface of the silicon dioxide substrate and has a distance with the upper surface of the silicon dioxide substrate; one end surface of the horizontal part is flush with one side surface of the silicon dioxide substrate;
and the inclined part is positioned in the silicon dioxide substrate, one end surface of the inclined part is integrally connected with the horizontal part, and the other end surface of the inclined part extends to the upper surface of the silicon dioxide substrate.
3. The femtosecond laser direct-write waveguide coupled superconducting nanowire single-photon detector as claimed in claim 2, wherein: the orthographic projection of the inclined part on the plane of the horizontal part is positioned on the extension line of the horizontal part.
4. The femtosecond laser direct-write waveguide coupled superconducting nanowire single-photon detector as claimed in claim 2, wherein: the inclined part and the surface of the silicon dioxide substrate form an included angle of 7-9 degrees.
5. The femtosecond laser direct-write waveguide coupled superconducting nanowire single-photon detector as claimed in claim 1, wherein: the number of the optical waveguides is multiple, and the optical waveguides are arranged in parallel at intervals; the number of the superconducting nanowires is multiple, and the plurality of superconducting nanowires and the plurality of optical waveguides are arranged in one-to-one correspondence.
6. The femtosecond laser direct-write waveguide coupled superconducting nanowire single photon detector as claimed in any one of claims 1 to 5, wherein: the femtosecond laser direct-writing waveguide coupled superconducting nanowire single photon detector further comprises an optical fiber, and the output end of the optical fiber is coupled with the end face of the optical waveguide, which is flush with one side face of the silicon dioxide substrate.
7. The femtosecond laser direct-write waveguide coupled superconducting nanowire single photon detector as claimed in any one of claims 1 to 5, wherein: the femtosecond laser direct-writing waveguide coupling superconducting nanowire single photon detector further comprises:
the V-shaped groove structure is attached to the side face of the silicon dioxide substrate, which is exposed out of the optical waveguide;
and the optical fiber is positioned in the V-shaped groove structure, and the output end of the optical fiber is coupled with the end face of one side face of the silicon dioxide substrate, which is flush with the optical waveguide.
8. The femtosecond laser direct-write waveguide coupled superconducting nanowire single-photon detector as claimed in claim 7, wherein: the femtosecond laser direct-writing waveguide coupling superconducting nanowire single photon detector further comprises optical cement, and the optical cement is located between the V-shaped groove structure and the silicon dioxide substrate.
9. A preparation method of a femtosecond laser direct-writing waveguide coupling superconducting nanowire single-photon detector is characterized by comprising the following steps:
providing a silicon dioxide substrate, and forming an optical waveguide in the silicon dioxide substrate by adopting a femtosecond laser direct writing process, wherein one end face of the optical waveguide is flush with one side face of the silicon dioxide substrate, and the other end face of the optical waveguide extends to the upper surface of the silicon dioxide substrate;
and forming a superconducting nanowire on the upper surface of the silicon dioxide substrate, wherein the superconducting nanowire is positioned on the end surface of the optical waveguide extending to the upper surface of the silicon dioxide substrate.
10. The method for preparing the femtosecond laser direct-writing waveguide coupled superconducting nanowire single photon detector according to claim 9, characterized in that: forming a plurality of optical waveguides in the silicon dioxide substrate by adopting a femtosecond laser direct writing process, wherein the optical waveguides are arranged in parallel at intervals; and forming a plurality of superconducting nanowires on the upper surface of the silicon dioxide substrate, wherein the plurality of superconducting nanowires and the plurality of optical waveguides are arranged in one-to-one correspondence.
11. The method for preparing the femtosecond laser direct-writing waveguide coupled superconducting nanowire single photon detector as claimed in claim 9 or 10, wherein the method comprises the following steps: the method also comprises the following steps after the superconducting nanowire is formed on the upper surface of the silicon dioxide substrate:
providing a V-shaped groove structure, wherein an optical fiber is arranged in the V-shaped groove structure;
and pasting the V-shaped groove structure on the side surface of the silicon dioxide substrate exposed out of the optical waveguide, and enabling the output end of the optical fiber to be flush with the optical waveguide and coupled with the end surface of one side surface of the silicon dioxide substrate.
12. The method for preparing the femtosecond laser direct-writing waveguide coupled superconducting nanowire single photon detector according to claim 11, wherein the method comprises the following steps: and adhering the V-shaped groove structure to the side surface of the silicon dioxide substrate exposed out of the optical waveguide by using optical cement.
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