CN110887514A - Stable tunable high-precision optical fiber tuning method and interferometer for QKD system - Google Patents
Stable tunable high-precision optical fiber tuning method and interferometer for QKD system Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
- G01D5/35306—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/255—Splicing of light guides, e.g. by fusion or bonding
Abstract
The scheme provides a stable tunable high-precision optical fiber tuning method and an interferometer for a QKD system, a cutting value is obtained, two arms of optical fibers of the interferometer are cut, and a coupling end of the optical fibers is fixed in an optical unit of the interferometer. And through tuning, the axial direction of the fused optical fiber is perpendicular to the end face of the coupling end, and the optical path difference between the fused optical fiber and the optical fiber of the fixed interferometer is finely adjusted after being lower than a threshold value, so that the interference fringes reach an optimal value. The stable tunable high-precision optical fiber interferometer comprises a coupling end of an optical fiber after fusion welding is fixed in an interferometer optical unit, a body reaches an adjusting component through an azimuth etalon after being wound around a shaft, and a tuning end is fixed on the adjusting component. The inner side of the interferometer shell is provided with a locking assembly, and the stretching piece is opposite to the locking assembly. By additionally arranging the adjusting component, the spliced optical fiber can be tuned, and the problem that the performance of a quantum key distribution system of discrete variables is unstable due to low adaptation success rate caused by untuneable arm length of an optical fiber interferometer in the prior art is solved.
Description
Technical Field
The invention relates to the field of communication, signal detection and sensing, in particular to a stable tunable high-precision optical fiber tuning method and an interferometer for a QKD system.
Background
A Quantum Key Distribution (QKD) system based on discrete variables of a BB84 protocol has an optical path structure, and the core is to perform orthogonal phase or time phase encoding and decoding by matching two groups of optical fiber type interferometers.
The interferometer is an asymmetric arm optical fiber interferometer, wherein one group of interferometers is used in the transmitter, the other group of interferometers is used in the receiver, and the two groups of interferometers are kept matched, namely the optical path errors of the two groups of interferometers are controlled within the order of hundreds of microns.
The optical fiber interferometer is an optical device manufactured based on the principle of light interference, and is used for measuring physical quantities such as micro displacement, deformation, temperature, phase, vibration and the like, and is also used for modulation, demodulation and the like in the field of optical information. The interference effect is controlled and measured by controlling the arm length difference of the interferometer in the fields of optical communication, engineering measurement, spectral analysis and the like, so the accuracy of the arm length and the arm length difference directly influences the performance of the interferometer and is the most important index of the interferometer.
The optical fiber interferometer is processed by adopting an optical fiber fusion method, the optical fiber fusion method is characterized in that two optical fibers are connected together after the end faces of the optical fibers are melted, and the precision of the existing optical fiber fusion method is in millimeter level (an optical fiber cutter and a ruler of an optical fiber fusion machine are in millimeter level).
In order to achieve the use standard that the optical path errors of two groups of interferometers are controlled within the order of hundreds of micrometers, the interferometers produced based on the optical fiber connection method are usually selected by a screening and matching mode of screening a large number of samples, but the success rate of adaptation is low, and the production cost is high. In actual use, when the interferometer is influenced by external environment and has errors, the interferometer needs to be matched again, and the performance of the quantum key distribution system with discrete variables is unstable.
Therefore, how to provide an interferometer with a tunable arm length becomes a problem to be solved urgently.
Disclosure of Invention
The invention provides a stable tunable high-precision optical fiber tuning method and interferometer for a QKD system, which are used for solving the problems that in the prior art, the optical fiber interferometer has low adaptation success rate due to the fact that the arm length cannot be tuned, and the performance of a quantum key distribution system of discrete variables is unstable due to the low adaptation success rate.
In order to achieve the above object, the present invention provides a method for tuning a stable tunable high-precision optical fiber for a QKD system, including: and cutting the optical fiber and welding the optical fiber after obtaining the cutting value, wherein a negative error exists between the length of the optical fiber and the cutting value. According to the tuning adjustment assembly of the two-dimensional scale, the axial direction of the optical fiber after welding is perpendicular to the end face of the coupling end of the optical fiber after welding, the horizontal direction and the vertical direction are consistent with the two-dimensional scale, and the optical path difference between the optical fiber after welding and the optical fiber of the fixed interferometer is lower than a threshold value. And carrying out fine adjustment on the optical fibers after fusion splicing to enable the interference fringes to reach an optimal value.
Preferably, the three-dimensional tuning assembly in the adjusting assembly is adjusted to make the fused optical fiber enter a state to be tuned.
Preferably, the height tuning knob in the three-dimensional tuning assembly is adjusted so that the tuning end, the body and the coupling end of the fused optical fiber are located on the same horizontal plane. And adjusting a transverse tuning knob in the three-dimensional tuning assembly to enable the tuning end and the coupling end to be in the same straight line.
Preferably, when the height tuning knob of the adjusting assembly is tuned, the fused optical fiber is made to be consistent with the horizontal scale of the two-dimensional scale; when the transverse tuning knob of the tuning adjusting component is tuned, the fused optical fiber is consistent with the vertical scale of the two-dimensional scale, and the fused optical fiber is not affected by tangential force.
Preferably, the fine tuning after the optical fiber is tuned according to the theoretical stretching length value comprises: after recording an initial value, tuning a transverse tuning knob of the adjusting assembly, and stretching the fused optical fiber according to a theoretical stretching length value to obtain a tuning value; and verifying whether the tuning value is correct or not by using a laser homodyne interferometry. And if the optical path difference obtained by the laser homodyne interferometry is less than 0.1 mm, the tuning value is correct, wherein the optical path difference is the optical path difference between the optical fiber of the fixed interferometer and the tuned fusion spliced optical fiber.
Preferably, if the tuning value is correct, the stretching member of the tuning assembly is tuned to finely tune the stretched optical fiber after fusion splicing so that the interference fringe distance is more than 50 nm and the optical fiber is locked.
In order to implement the method, the technical scheme of the invention also provides a stable tunable high-precision optical fiber interferometer for a QKD system, which comprises the following steps: the optical fiber splicing device comprises a spliced optical fiber, an adjusting component, an interferometer optical unit, a shaft and a locking device, wherein the adjusting component comprises a three-dimensional tuning component and a stretching piece;
the locking assembly is fixed on the inner side of the interferometer shell and is adjacent to the three-dimensional tuning assembly, and the stretching piece is arranged opposite to the fastening assembly by taking the side edge of the interferometer shell as an axis.
Preferably, in the above-described aspect, the axis is provided on a side close to the interferometer optical unit.
Preferably, as for the above technical solution, the three-dimensional tuning assembly includes a horizontal tuning knob, a height tuning knob and a clamping fixture, the horizontal tuning knob is disposed on a side surface of the three-dimensional tuning assembly, the height tuning knob is disposed on a top of the three-dimensional tuning assembly, and the horizontal tuning knob and the height tuning knob are used in cooperation, so that a tuning end, a body portion and a coupling end of the fused optical fiber are in a straight line, and the straight line is in accordance with the direction of the two-dimensional scale. The horizontal scale of the two-dimensional scale is vertically arranged in the interferometer shell and is close to the three-dimensional tuning assembly, the vertical scale is arranged on the inner bottom surface of the interferometer shell, and the horizontal scale and the vertical scale form a right angle.
As the optimization of the above technical scheme, preferably, the fused optical fiber, the adjusting assembly, the interferometer optical unit, the shaft and the locking assembly are packaged in the interferometer housing; the outer side of interferometer shell is located to the tensioning member, and is relative with locking device, and the tensioning member can tune the optic fibre after the butt fusion.
The technical scheme of the invention provides a stable tunable high-precision optical fiber tuning method for a QKD system, which is characterized in that after a cutting value is obtained according to parameter requirements, two arms of optical fibers of an interferometer are cut and then are welded, and the length of the optical fibers and the cutting value have negative errors; the axial direction of the fused optical fiber is perpendicular to the end face of the coupling end of the fused optical fiber through the tuning adjusting assembly, and the refractive index stretching variation is lower than a threshold value; and tuning the adjusting component to stretch the spliced optical fiber according to the theoretical stretching length value so as to enable the interference fringes to reach an optimal value.
The technical scheme of the invention also provides a stable tunable high-precision optical fiber interferometer for the QKD system, wherein the coupling end of the fused optical fiber is fixed in the interferometer optical unit, the body part of the fused optical fiber passes through the adjusting component after being wound around the shaft, and the tuning end of the fused optical fiber is fixed on the adjusting component. The azimuth etalon is arranged between the axial shaft and the three-dimensional tuning assembly; the locking assembly fixes the inner side of the interferometer shell and is adjacent to the three-dimensional tuning assembly, and the stretching piece is arranged opposite to the fastening assembly by taking the side edge of the interferometer shell as an axis.
According to the invention, the adjusting assembly is additionally arranged in the existing interferometer, so that the optical fiber after fusion splicing can be adjusted on a three-dimensional coordinate axis, and the problem that the optical fiber after fusion splicing is influenced by tangential force and has uneven refractive index is avoided; and the optical fiber after stretching and welding is finely adjusted by the tuning adjusting component, so that the interference fringes reach the optimal value finally, the arm length of the interferometer can be adjusted, and the defects of high precision requirement, low productivity and yield, unstable performance and the like of the conventional optical fiber interferometer preparation instrument are overcome. The problems that the optical fiber interferometer in the prior art is low in adaptation success rate due to the fact that the arm length cannot be tuned, and the performance of a quantum key distribution system of discrete variables is unstable due to the low adaptation success rate are solved. The interferometer has the advantages that the arm length is adjustable, the arm length can be flexibly configured according to different use requirements, the manufacturing method is simple, and the requirements on equipment precision and manual proficiency are low; the error in the manufacturing process is controllable.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief description will be given below of the drawings required for the embodiments or the technical solutions in the prior art, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a first flowchart illustrating a method for tuning a stably tunable high-precision optical fiber for a QKD system according to an embodiment of the present invention.
Fig. 2 is a schematic flowchart of a stable tunable high-precision optical fiber tuning method for a QKD system according to an embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a stable tunable high-precision fiber interferometer for a QKD system according to an embodiment of the present invention.
Fig. 4 is a schematic perspective view of a stable tunable high-precision fiber interferometer for a QKD system according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Now, a description is given to a stable tunable high-precision optical fiber tuning method for a QKD system provided by the present invention, and fig. 1 is a schematic flow chart provided in an embodiment of the present invention:
and step 101, obtaining a trimming value, trimming the optical fiber and welding.
A negative error is maintained between the length of the optical fiber and the cutoff value, which is obtained according to parameter requirements.
And 102, tuning the adjusting component to enable the fused optical fiber to enter a state to be tuned.
The tuning assembly includes a three-dimensional tuning assembly and an azimuth etalon.
Specifically, the axial direction of the fused optical fiber is perpendicular to the end face of the coupling end of the fused optical fiber. And adjusting a height tuning knob and a transverse tuning knob in the three-dimensional tuning assembly according to the two-dimensional scale, so that the tuning end, the body part and the coupling end of the fused optical fiber are positioned on the same horizontal plane, and the tuning end and the coupling end are positioned on the same straight line. The optical fiber after welding is respectively consistent with the horizontal scale and the vertical scale of the two-dimensional scale in the horizontal direction and the vertical direction, so that the optical fiber after welding is not influenced by tangential force.
And 103, tuning the fused optical fiber according to the theoretical stretching length value, and then performing fine tuning to enable the interference fringe to reach an optimal value.
The method specifically comprises the following steps:
and recording the initial value, tuning a transverse tuning knob of the adjusting component, and stretching the fused optical fiber according to the theoretical stretching length value to obtain a tuning value. And then, verifying whether the tuning value is correct by using a laser homodyne interferometry, and if the optical path difference between the fused optical fiber obtained by the laser homodyne interferometry and the target optical fiber to be matched is lower than 0.1 mm, determining that the tuning value is correct.
If the optical fiber is correct, the stretching piece of the tuning adjusting assembly finely adjusts the fused optical fiber, so that the distance between interference fringes is more than 50 nanometers, and then the stretched fused optical fiber is locked by the locking device.
The optical path difference is the optical path difference between the optical fiber of the fixed interferometer and the tuned fused optical fiber.
A method for tuning a stable, tunable and high-precision optical fiber for a QKD system according to the present invention will now be described in detail, as shown in fig. 2:
step 201, measuring the length of the optical fiber to obtain a cutting value, cutting the optical fiber and pulling out the optical fiber cladding.
Specifically, the cutting value is marked according to actual needs by measuring the length of the optical fiber by using a scale guide rail and an optical fiber clamping and fixing device. And cutting the optical fiber by using the optical fiber cutting device, and pulling out the optical fiber cladding under the condition that the length of the optical fiber and the calculated value keep a negative error, wherein the negative error is about 1 mm.
And step 202, welding the cut optical fibers by using an optical fiber welding machine to obtain the welded optical fibers.
And 203, fixing the coupling end of the fused optical fiber on a flange plate, and fixing the tuning end on a clamping tool of the three-dimensional tuning assembly.
The flange plate of the method is a flange plate of an interferometer optical unit and is fixed in the interferometer optical unit through a thread buckle.
And 204, adjusting the coupling end, the body part and the tuning end of the fused optical fiber to be horizontal.
Specifically, because the two ends of the fused optical fiber are not completely horizontal, a height tuning knob in the three-dimensional tuning assembly needs to be tuned, and meanwhile, the coupling end, the body part and the tuning end are adjusted to the same height by referring to a horizontal scale arranged in the interferometer shell.
And step 205, adjusting the coupling end and the tuning end of the fused optical fiber to be axisymmetric.
Specifically, after the tuning, the coupling end and the tuning end of the fused optical fiber are not in an axisymmetric state, i.e., the axial direction of the fused optical fiber is not completely perpendicular to the coupling end face. And tuning a transverse tuning knob in the three-dimensional tuning assembly, and referring to a vertical scale arranged on the inner bottom surface of the interferometer shell to enable the coupling end and the tuning end to be at the same transverse position, wherein the final state is that the axial direction of the optical fiber is vertical to the coupling end surface.
Specifically, the two-dimensional scale is used for adjusting the pointing angle of the fused optical fiber, so that the body of the fused optical fiber is not extruded with a side object (barrier) to generate a tangential force, and the problem of uneven refractive index of the optical fiber caused by the fact that the axial direction of the dissolved optical fiber is not perpendicular to the coupling end face due to the generation of the tangential force is avoided.
Wherein, the two-dimensional scale can also be replaced by an azimuth etalon.
And step 206, tuning the transverse tuning knob according to the theoretical stretching length value to stretch the fused optical fiber.
Specifically, the lateral tuning knob is described by taking a micrometer as an example:
recording an initial micrometer scale value 1, tuning the micrometer to a micrometer scale value 2 according to a theoretical stretching length value obtained by formula calculation, wherein the micrometer scale value 2 is a tuning value.
In the process of stretching the optical fiber after welding, the optical path variation amount is as follows along with the change of stress:
Δx＝n(λ)×ΔL(X)+Δn(X)×L (1)
wherein Δ x is the optical path variation; n (λ) is a refractive index of a specific wavelength; the wavelength selected by the embodiment is 1550 nanometers, and other wavelengths can be set according to practical application scenes; Δ L is the amount of change in length stretch (theoretical stretch length value); x is an optical path variable; Δ n (x) is a refractive index stretch change amount, and L is a physical length of the optical fiber after fusion splicing before stretching (initial micrometer scale value 1).
Since stretching is elastic deformation, the values of Δ l (x) LX, Δ n (x) n (λ) × C are approximatedXX, wherein, CXIs the tensile strain coefficient.
Thus, the increment of the fiber length and refractive index with the change of stress is:
Δx＝n(λ)×L×[1+CX]×(X) (2)
and step 207, verifying whether the micrometer scale value 2 is correct by using a laser homodyne interference method.
And if the optical path difference measured by the laser homodyne interferometry is lower than 0.1 mm, the scale value 2 of the micrometer is correct, and otherwise, the tuning step is carried out again.
And step 208, fine adjustment is carried out on the fused optical fiber by the tuning tensile piece.
Specifically, a wide-spectrum light source (the light source wavelength range is 1550 +/-50 nanometers), a fixed interferometer, a tunable interferometer and a spectrometer are physically connected by using an optical fiber jumper.
If the correction is correct, the micrometer is tuned, so that the scale value of the micrometer is 2 to 3, and the interference fringes on the spectrometer reach the optimal value, namely the distance between the interference fringes reaches more than 50 nanometers.
And 209, locking the trimmed fusion-spliced optical fiber through a locking device.
A description will now be given of a stable tunable high-precision fiber optic interferometer for QKD systems, as provided by the present invention, as shown in fig. 3 and 4, which includes:
The coupling end of the fused optical fiber 1 is fixed in the interferometer optical unit 2, the body of the fused optical fiber passes through the two-dimensional scale 5 after being wound around the shaft 3, and the tuning end of the fused optical fiber 1 is fixed on the clamping tool 9. Wherein the axis 3 is arranged at a side close to the interferometer light unit 2. As shown in fig. 3 and 4, the shaft 3 may be a cylinder, and may be selectively installed around the shaft 3, or when the optical fiber is short, the shaft 3 may not be installed; the material around the shaft 3 is preferably a ceramic material with a smooth ceramic surface, so that the length difference range of the arm length of the interferometer can be effectively widened.
The horizontal scale vertical 51 of the two-dimensional scale 5 is arranged in the interferometer shell and is close to the three-dimensional tuning assembly, the vertical scale 52 is arranged on the inner bottom surface of the interferometer shell, the horizontal scale 51 and the vertical scale 52 form a right angle, and the two-dimensional scale 5 is used for adjusting the pointing angle of the fused optical fiber.
A lateral tuning knob 7 is provided at the side of the three-dimensional tuning assembly and a height tuning knob 8 is provided at the top of the three-dimensional tuning assembly. The transverse tuning knob 7, the height tuning knob 8 and the two-dimensional scale 5 are matched for use, so that the pointing angle of the optical fiber after fusion splicing is realized, and the coupling end, the body part and the tuning end of the optical fiber 1 after fusion splicing are in a straight line and are parallel to the bottom surface of the interferometer shell.
At this time, the optical fiber 1 after fusion splicing is finely adjusted by the tuning tension piece 6, so that the interferometer arm length optical path difference G2 is close to the matching interferometer arm length optical path difference G1, and the precision is in millimeter order, and the tuning process of the optical fiber 1 after fusion splicing is finished.
Wherein the matching interferometer is a fixed interferometer with a prefabricated asymmetric optical arm.
A locking device 4 secures the inside of the interferometer housing adjacent to the three-dimensional tuning assembly. The stretching piece 6 is arranged on the outer side of the side edge of the interferometer, the side edge of the interferometer shell is used as an axis and is arranged opposite to the fastening assembly, when the precision between the interferometer arm length optical path difference G2 and the matching interferometer arm length optical path difference G1 is reduced in the using process, the fusion spliced optical fiber 1 can be retuned to enable the fusion spliced optical fiber 1 and the matching interferometer arm length optical path difference G1 to be matched, and the performance stability of a quantum key distribution system with discrete variables can be kept.
And finally, packaging the fused optical fiber 1, the adjusting assembly, the interferometer optical unit 2, the shaft 3 and the locking device 4 in the interferometer shell, and installing and fixing the interferometer upper cover to finish packaging.
According to the invention, the adjusting component is additionally arranged in the existing interferometer, so that the optical fiber after fusion splicing can be adjusted on a three-dimensional coordinate axis, and the problem that the optical fiber after fusion splicing is influenced by tangential force and has uneven refractive index can be avoided. The optical fiber after stretching and welding is finely adjusted through the tuning adjusting assembly, so that interference fringes reach an optimal value, the arm length of the interferometer is adjustable, and the defects that an existing optical fiber interferometer preparation instrument is high in precision requirement, low in productivity and yield, unstable in performance and the like are overcome. The problems that the optical fiber interferometer in the prior art is low in adaptation success rate due to the fact that the arm length cannot be tuned, and the performance of a quantum key distribution system of discrete variables is unstable due to the low adaptation success rate are solved. The interferometer has the advantages that the arm length is adjustable, the arm length can be flexibly configured according to different use requirements, the manufacturing method is simple, and the requirements on equipment precision and manual proficiency are low; the error in the manufacturing process is controllable.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A method of stably tunable high precision fiber tuning for QKD systems, comprising:
cutting the optical fiber after obtaining the cutting value, and welding to obtain a welded optical fiber, wherein a negative error exists between the length of the optical fiber and the cutting value;
according to the two-dimensional scale tuning adjustment assembly, the axial direction of the fused optical fiber is perpendicular to the end face of the coupling end of the fused optical fiber, the horizontal direction and the vertical direction of the fused optical fiber are consistent with those of the two-dimensional scale, and the optical path difference between the fused optical fiber and the optical fiber of the fixed interferometer is lower than a threshold value;
and finely adjusting the optical fibers after fusion splicing to enable the interference fringes to reach an optimal value.
2. A method of stably-tunable high-precision optical fiber tuning for a QKD system according to claim 1, said method comprising:
and adjusting the three-dimensional tuning assembly in the adjusting assembly to enable the fused optical fiber to enter a state to be tuned.
3. A method of stably-tunable high-precision optical fiber tuning for a QKD system according to claim 2, said method comprising:
adjusting a height tuning knob in the three-dimensional tuning assembly to enable a tuning end, a body part and a coupling end of the fused optical fiber to be positioned on the same horizontal plane;
and adjusting a transverse tuning knob in the three-dimensional tuning assembly to enable a tuning end and the coupling end to be on the same straight line.
4. A method of stably-tunable high-precision optical fiber tuning for a QKD system according to claim 1 or 3, said method comprising:
when a height tuning knob of the adjusting assembly is tuned, enabling the fused optical fiber to be consistent with a horizontal scale of the two-dimensional scale;
when the transverse tuning knob of the adjusting assembly is tuned, the fused optical fiber is consistent with the vertical scale of the two-dimensional scale, and the fused optical fiber is not influenced by tangential force.
5. The method of claim 1 and 4, wherein said tuning said post-fusion optical fiber according to a theoretical draw length value and then performing a fine tuning comprises:
after recording an initial value, tuning a transverse tuning knob of the adjusting assembly, and stretching the fused optical fiber according to a theoretical stretching length value to obtain a tuning value;
verifying whether the tuning value is correct by using a laser homodyne interference method;
and if the optical path difference obtained by the laser homodyne interferometry is lower than 0.1 mm, the tuning value is correct, wherein the optical path difference is the optical path difference between the optical fiber of the fixed interferometer and the tuned fusion-spliced optical fiber.
6. A method of stably-tunable high-precision optical fiber tuning for a QKD system according to claim 5, characterized in that it comprises:
and if the tuning value is correct, tuning the stretching piece of the adjusting assembly to finely adjust the stretched fused optical fiber so that the distance between interference fringes is more than 50 nanometers and the optical fiber is locked.
7. A stable tunable high precision fiber interferometer for QKD systems that enables the high precision fiber tuning method of any of claims 1-6, comprising:
the optical fiber fusion splicer comprises a fused optical fiber, an adjusting component, an interferometer optical unit, a shaft and a locking device, wherein the adjusting component comprises a three-dimensional tuning component and a stretching component,
the coupling end of the fused optical fiber is fixed in the interferometer optical unit, the body part of the fused optical fiber passes through the adjusting component after being wound around the shaft, and the tuning end of the fused optical fiber is fixed on the adjusting component;
the locking assembly is fixed on the inner side of the interferometer shell and adjacent to the three-dimensional tuning assembly, and the stretching piece is arranged opposite to the fastening assembly by taking the side edge of the interferometer shell as an axis.
8. A stably-tunable high-precision fiber optic interferometer for a QKD system according to claim 6, wherein said axis is disposed on a side adjacent to said interferometer optics unit.
9. The stably-tunable high-precision fiber optic interferometer for a QKD system according to claim 6, wherein said three-dimensional tuning assembly includes, a lateral tuning knob, a height tuning knob, and a clamping fixture,
the transverse tuning knob is arranged on the side surface of the three-dimensional tuning assembly, the height tuning knob is arranged on the top of the three-dimensional tuning assembly, and the transverse tuning knob and the height tuning knob are matched for use, so that the tuning end, the body part and the coupling end of the fused optical fiber are in a straight line, and the direction of the straight line is consistent with that of the two-dimensional scale;
the horizontal scale of the two-dimensional scale is vertically arranged in the interferometer shell and is close to the three-dimensional tuning assembly, the vertical scale is arranged on the inner bottom surface of the interferometer shell, and the horizontal scale and the vertical scale form a right angle.
10. A stably-tunable high-precision fiber interferometer for a QKD system according to claim 6 or 9,
the fusion spliced optical fiber, the adjusting assembly, the interferometer optical unit, the winding shaft and the locking assembly are packaged in the interferometer shell;
the stretching piece is arranged on the outer side face of the interferometer shell and opposite to the locking device, and the stretching piece can tune the optical fiber after welding.
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| US10444003B2 (en) * | 2016-12-05 | 2019-10-15 | Quality Vision International, Inc. | Exchangeable lens module system for probes of interferometric optical measuring machines |
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| CN105865754A (en) * | 2016-05-18 | 2016-08-17 | 哈尔滨工程大学 | Measuring device for length difference between arms of optical fiber interferometer |
| US10444003B2 (en) * | 2016-12-05 | 2019-10-15 | Quality Vision International, Inc. | Exchangeable lens module system for probes of interferometric optical measuring machines |
| CN106950673A (en) * | 2017-04-10 | 2017-07-14 | 三峡大学 | A kind of non-equilibrium Optical Fiber Michelson Interferometer brachium adjusting means |
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Application publication date: 20200317 |