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CN-122018217-A - Full-quartz optical fiber Fabry-Perot interference element and preparation method thereof

CN122018217ACN 122018217 ACN122018217 ACN 122018217ACN-122018217-A

Abstract

The invention provides an all-quartz optical fiber Fabry-Perot interference element and a preparation method thereof, the element comprises a single-mode transmission optical fiber, a hollow optical fiber and an end quartz pressure-sensitive membrane which are connected in sequence, and jointly enclose a Fabry-Perot optical interference cavity. The quartz material in the interference cavity is subjected to non-contact local ultra-fast thermal quenching modification treatment (suspended in a folded carbon paper slit, subjected to 1150-1220 ℃ flash joule heat second-level heat preservation under negative pressure and inert gas and fast cooled) to form a densification reforming state medium. The invention thoroughly eliminates the nano-scale density heterogeneity and low-density dark spots left by microcavity processing, and well maintains the mechanical integrity of the pressure sensing diaphragm while endowing the interference element with extremely high-temperature drift stability, thereby greatly improving the service reliability and test repeatability of the sensor.

Inventors

  • HAI ZHENYIN
  • XUE CHENYANG
  • LIU ZHICHUN
  • ZHANG QI

Assignees

  • 厦门大学

Dates

Publication Date
20260512
Application Date
20260410

Claims (10)

  1. 1. The full-quartz optical fiber Fabry-Perot interference element is characterized by comprising a single-mode transmission optical fiber, a hollow optical fiber and an end quartz pressure-sensitive membrane which are sequentially connected, wherein the single-mode transmission optical fiber, the hollow optical fiber and the end quartz pressure-sensitive membrane jointly enclose a Fabry-Perot optical interference cavity, quartz materials in the Fabry-Perot optical interference cavity undergo non-contact local ultra-fast thermal quenching modification treatment to form a densified reforming state medium, the modification treatment comprises that the Fabry-Perot optical interference cavity is positioned in a slit gap area formed by folded carbon paper and kept in a non-contact state with a current-carrying heating layer, and the Fabry-Perot optical interference cavity is subjected to 1150-1220 ℃ local radiation and convection thermal field based on flash joule heat generation under the protection of sealed negative pressure and inert gas, and is rapidly cooled to 20-200 ℃ after second-level heat preservation.
  2. 2. The all-quartz fiber Fabry-Perot interferometer component of claim 1, wherein the densified reforming state medium is a continuous uniform solid structure in microscopic morphology, free of nanoscale density heterogeneity, free of low density region defects, and free of dark spots.
  3. 3. The all-quartz fiber Fabry-Perot interferometer component of claim 1, wherein the end quartz pressure sensitive membrane has a physical structure free of plastic deformation and free of microcracks after undergoing the modifying treatment.
  4. 4. The all-quartz fiber Fabry-Perot interferometer of claim 1, wherein the peak temperature of the local radiation and convection thermal field is 1200 ℃ and the time for second-order incubation is 1s to 30s.
  5. 5. The all-quartz fiber Fabry-Perot interferometer of claim 4, wherein the modifying treatment comprises 1-10 periodic heat treatment cycles.
  6. 6. The all-quartz fiber Fabry-Perot interferometer of claim 5, wherein the second-order incubation time is 5s to 15s, and the modifying treatment comprises 3 to 7 periodic heat treatment cycles.
  7. 7. The all-quartz fiber Fabry-Perot interferometer element of claim 1, wherein the sealing negative pressure defining the modification treatment is-0.05 MPa, and the inert gas is argon.
  8. 8. A method of fabricating an all-quartz fiber Fabry-Perot interferometer element of any of claims 1-7, comprising: s1, providing an initial interference element which is formed by sequentially connecting a single-mode transmission optical fiber, a hollow optical fiber and an end quartz pressure sensing diaphragm and internally provided with a Fabry-Perot optical interference cavity; s2, installing the initial interference element in a slit gap area formed by folding carbon paper, so that the area where the Fabry-Perot optical interference cavity is located and the current-carrying heating layer are arranged in a non-contact mode; S3, placing the installed initial interference element in a sealed processing cavity, and heating the area of the Fabry-Perot optical interference cavity by adopting a local rapid heating mode based on flash evaporation Joule heat under the protection conditions of negative pumping pressure and inert gas introduction to ensure that the temperature reaches the peak temperature of a local radiation and convection thermal field of 1150-1220 ℃; S4, after maintaining second-level heat preservation time at the peak temperature, rapidly cooling to 20-200 ℃ to complete single local ultra-fast thermal quenching cycle; S5, repeating the local ultrafast thermal quenching and cooling cycle for a plurality of times to enable the quartz material in the Fabry-Perot optical interference cavity to undergo microstructure relaxation and densification reforming, so as to obtain the full quartz fiber Fabry-Perot interference element.
  9. 9. The preparation method of the super-rapid thermal quenching device according to claim 8, wherein the peak temperature of the local radiation and convection thermal field is 1200 ℃, the second-level heat preservation time is 5 s-15 s, and the repetition number of the local super-rapid thermal quenching cycle is 3-7.
  10. 10. The method according to claim 8, wherein in S2, the initial interference element is positioned at a gap center position in the gap region of the slit, and in S3, the relative pressure of the negative pumping pressure is controlled to be-0.05 MPa, and the inert gas is high purity argon.

Description

Full-quartz optical fiber Fabry-Perot interference element and preparation method thereof Technical Field The invention relates to the technical field of optical components, in particular to an all-quartz optical fiber Fabry-Perot interference element and a preparation method thereof. Background The optical fiber Fabry-Perot pressure sensor has the advantages of small volume, light weight, high temperature resistance, strong electromagnetic interference resistance, suitability for long-distance transmission and easiness in working in complex electromagnetic environments, and has good application prospects in the fields of aeroengine hot end testing, combustion flow field diagnosis, hypersonic wind tunnel testing, extreme environment in-situ measurement and the like. In particular, in the scene that the traditional electrical sensor such as high temperature, high pressure, strong vibration, strong electromagnetic interference and the like is difficult to stably work for a long time, the FP pressure sensor constructed based on the quartz optical fiber shows obvious advantages. The conventional optical fiber FP pressure sensor generally utilizes two reflection interfaces to form a Fabry-Perot interference cavity, and external pressure acts on a sensitive diaphragm to cause cavity length change, so that interference spectrum shifts, and pressure measurement is realized according to the interference spectrum. For FP pressure sensors operating in high temperature environments, in addition to pressure-induced cavity length changes, temperature changes can also affect the optical response of the interference cavity by means of material thermal expansion, elastic modulus changes, residual stress release, refractive index fluctuations, microstructure evolution, and the like, resulting in sensor output that includes both temperature and pressure effects. To obtain accurate pressure measurement results, calibration of sensor temperature drift characteristics is generally required, and a corresponding temperature compensation model is established. However, in practical high temperature applications, the existing quartz fiber FP pressure sensor generally has the problem of insufficient temperature drift response stability. The method is characterized in that after the sensor is subjected to multiple heating-cooling thermal cycles, the interference spectrum drift curve of the sensor often has the phenomena of inconsistent cycles, obvious baseline deviation, poor repeatability and the like. This type of phenomenon suggests that the thermal response of the sensor is not entirely determined by reversible thermal expansion or thermo-optic effects, but is accompanied by some degree of irreversible structural evolution. For a high-temperature pressure measurement system which relies on a temperature drift model to carry out temperature compensation, once obvious historical dependence and unrepeatability exist in a thermal cycle process, the temperature drift model obtained based on single calibration is difficult to be stably applied in a subsequent working condition, so that compensation errors are increased, pressure inversion precision is reduced, and even the model is invalid when serious. Further analysis shows that the problems are closely related to the unbalanced structural state of the quartz material in the preparation and service processes. The quartz optical fiber is subjected to severe temperature change from high temperature melting to rapid cooling and rapid shrinkage and shaping of geometric dimensions in the drawing forming process, so that the problems of residual stress, uneven local density distribution, microscopic defect accumulation, inconsistent structure relaxation degree and the like are easily caused, and further the problem of refractive index fluctuation of an optical transmission medium is caused. When the sensor is subjected to repeated thermal cycling in a high-temperature environment, the unbalanced structure is continuously adjusted, and the refractive index of an optical medium at a reflecting interface of the FP cavity is irreversibly changed, so that the optical response of the FP cavity is shifted along with the thermal history. This drift is not a simple linear temperature response but has certain evolution characteristics and therefore directly affects the repeatability and portability of the high temperature calibration results. In order to solve the above problems, a conventional furnace annealing method is generally adopted in the prior art to perform heat treatment on a quartz optical fiber device, so as to release internal stress and improve material stability through constant temperature annealing for a long time. Although the method can improve the thermal stability of part of devices to a certain extent, the method has the following defects that firstly, the conventional furnace annealing has slower temperature rise and temperature fall speeds, the whole treatment period is long,