CN-117945641-B - Active optical fiber preform, preparation method and application thereof

CN117945641BCN 117945641 BCN117945641 BCN 117945641BCN-117945641-B

Abstract

The invention provides an active optical fiber preform and a preparation method and application thereof, wherein the active optical fiber preform comprises the following steps of immersing a silica loose body in a solution containing rare earth chloride to obtain a first intermediate, placing the first intermediate in an MCVD lathe, simultaneously introducing oxygen and helium for pre-oxidation treatment, and continuing to introduce oxygen and helium for oxidation treatment to obtain a second intermediate, wherein the introducing flow of oxygen in the pre-oxidation treatment is V1, the introducing flow of oxygen in the oxidation treatment is V2, the condition that V1: V2 = 1 (5-10) is satisfied, the temperature of the oxidation treatment is higher than the temperature of the pre-oxidation treatment, the pressure of the pre-oxidation treatment is higher than the pressure of the oxidation treatment, and after the second intermediate is subjected to sintering treatment and shrinking treatment in sequence, the active optical fiber preform is obtained, so that the full oxidation of rare earth elements and the maximum removal of hydroxyl groups can be realized, the optical fiber loss can be reduced, and the preparation method has excellent environmental protection and safety and is suitable for mass production.

Inventors

ZHANG JUNYI
SHEN YICHUN
QIN YU
JIANG XINLI
CHEN YALI
DING SONG

Assignees

中天科技精密材料有限公司
江苏中天科技股份有限公司

Dates

Publication Date: 20260505
Application Date: 20240205

Claims (10)

1. The preparation method of the active optical fiber preform is characterized by comprising the following steps: Immersing the loose silica body into a solution containing rare earth chloride to obtain a first intermediate; Placing the first intermediate in an MCVD lathe, simultaneously introducing oxygen and helium for pre-oxidation treatment, and continuing to introduce oxygen and helium for oxidation treatment to obtain a second intermediate, wherein the flow of oxygen in the pre-oxidation treatment is V1, the flow of oxygen in the oxidation treatment is V2, and the V1: V2 = 1 (5-10) is satisfied, the temperature of the oxidation treatment is higher than that of the pre-oxidation treatment, and the pressure of the pre-oxidation treatment is higher than that of the oxidation treatment; And sintering the second intermediate in sequence, and performing shrinkage melting treatment to obtain the active optical fiber preform.
2. The preparation method according to claim 1, wherein the flow rate of helium gas in the pre-oxidation treatment is V3, and the flow rate of helium gas in the oxidation treatment is V4, and v3:v4= (2-3): 1 is satisfied.
3. The method according to claim 2, wherein in the pre-oxidation treatment, the flow rate of oxygen is 50 to 200sccm, the flow rate of helium is 500 to 2000sccm, and/or, In the oxidation treatment, the oxygen gas flow rate is 500-1000 sccm, and the helium gas flow rate is 500-1000 sccm.
4. The method according to claim 1, wherein the pre-oxidation treatment is carried out at a temperature of 200 to 500 ℃, at a pressure of 0.9 to 1.5 atm, for a time of 1.8 to 3.5 hours, and/or, The temperature of the oxidation treatment is 400-800 ℃, the pressure is 0.6-0.9 atmosphere, and the time is 1.5-2 h.
5. The method according to claim 4, wherein the MCVD lathe includes at least a flame torch, a first clamping unit, and a second clamping unit; the first clamping unit and the second clamping unit rotate along the axis of the first clamping unit and the second clamping unit are used for mutually matching and clamping the first intermediate; The flame burner moves reciprocally along the axial direction of the first intermediate body, and the spraying direction of the flame burner faces the first intermediate body; In the pre-oxidation treatment process, starting the flame spraying lamp to enable the flame spraying lamp to perform first reciprocating movement along the axial direction of a first intermediate body, wherein the first clamping unit and the second clamping unit drive the first intermediate body to perform first rotation; in the oxidation treatment process, the flame spraying lamp is started to make the flame spraying lamp perform second reciprocating movement along the axial direction of the first intermediate body; The rotating speed of the first rotation is 10-30 rpm, and the rotating speed of the second rotation is 10-30 rpm; The speed of the first reciprocating movement is 50-100 mm/min, and the speed of the second reciprocating movement is 50-100 mm/min.
6. The method according to claim 1, wherein the rare earth chloride-containing solution contains at least one element of Y, ce, nd, yd, tm, er and/or, The solvent in the solution containing rare earth chloride comprises at least one of methanol, ethanol and glycol.
7. The method according to claim 6, wherein the rare earth chloride-containing solution further contains at least one element selected from the group consisting of Al and P.
8. The production method according to any one of claims 1 to 7, wherein the sintering treatment and the shrinking treatment are performed in a mixed atmosphere containing oxygen and helium; In the mixed atmosphere, the volume ratio of oxygen to helium is 1 (1-2).
9. An active optical fiber preform manufactured by the manufacturing method according to any one of claims 1 to 8.
10. An optical fiber prepared by using the active optical fiber preform of claim 9.

Description

Active optical fiber preform, preparation method and application thereof Technical Field The invention belongs to the technical field of optical fibers, and particularly relates to an active optical fiber preform, a preparation method and application thereof. Background With the development of laser materials and laser technology, researchers find that by doping rare earth elements into an active optical fiber to form a doped layer with a certain concentration, the optical fiber has remarkable absorption and emission characteristics for light with a certain wavelength, and can realize more excellent spectral characteristics and optical efficiency. The rare earth doped active optical fiber is widely applied to an optical fiber sensor at present, and is used as an important gain medium in an optical fiber laser, the performance of the laser is directly determined by the performance of the rare earth doped active optical fiber, a preform is the preparation basis of the optical fiber, the performance of the preform directly influences the performance of the optical fiber, and therefore, how to prepare the optical fiber preform with excellent performance is the research focus in the field. At present, the method for doping rare earth elements into the active optical fiber comprises a gas phase method and a liquid phase method, wherein the gas phase method comprises rare earth chloride gas phase deposition and rare earth chelate gas phase deposition, and the liquid phase method comprises an in-tube rare earth solution soaking method and an out-tube rare earth solution soaking method. The gas phase method depends on large deposition equipment, and the doping concentration and uniformity are difficult to control, so that the performance of the optical fiber is not improved; the liquid phase method is to deposit the optical fiber perform in the deposition tube by MCVD lathe, then soak the optical fiber perform in rare earth solution, get the rare earth doped active optical fiber perform after oxidation, drying and sintering, wherein the in-tube rare earth solution soaking method is to soak the rare earth solution in the deposition tube, the technology needs to use chlorine to dry to remove the hydroxyl brought by solution soaking, thus realizing low loss of the perform, but the long time chlorine is introduced to cause corrosion of the pipeline and damage of the lathe, the out-tube rare earth solution soaking method is to soak the rare earth solution outside the deposition tube, the technology does not need chlorine introduced in the subsequent drying step, but the hydroxyl in the preform cannot be completely removed without chlorine, finally resulting in the increase of the loss of the prepared optical fiber, and the high-loss optical fiber used in the optical fiber laser can further cause the power reduction of the laser. Therefore, how to provide a preparation method of an optical fiber preform that is environment-friendly, safe and capable of effectively reducing optical fiber loss is a technical problem to be solved in the art. Disclosure of Invention The preparation method of the active optical fiber preform provided by the invention realizes gradual oxidation by utilizing pre-oxidation treatment and oxidation treatment, limits the flow of oxygen, can realize full oxidation of rare earth elements and remove hydroxyl to the maximum extent, is beneficial to reducing optical fiber loss, has excellent environmental protection and safety, and is suitable for mass production. The invention provides an active optical fiber preform, which has the advantage of low loss due to the adoption of the preparation method. The invention also provides an optical fiber, which has the advantage of low loss due to the fact that the optical fiber is prepared by adopting the active optical fiber preform. In a first aspect of the present invention, there is provided a method for preparing an active optical fiber preform, comprising the steps of: Immersing the loose silica body into a solution containing rare earth chloride to obtain a first intermediate; Placing the first intermediate in an MCVD lathe, simultaneously introducing oxygen and helium for pre-oxidation treatment, and continuing to introduce oxygen and helium for oxidation treatment to obtain a second intermediate, wherein the flow of oxygen in the pre-oxidation treatment is V1, the flow of oxygen in the oxidation treatment is V2, and the V1: V2 = 1 (5-10) is satisfied, the temperature of the oxidation treatment is higher than that of the pre-oxidation treatment, and the pressure of the pre-oxidation treatment is higher than that of the oxidation treatment; And sintering the second intermediate in sequence, and performing shrinkage melting treatment to obtain the active optical fiber preform. According to the preparation method, the inflow rate of helium in the pre-oxidation treatment is V3, and the inflow rate of helium in the oxidation treatment is V4, so that v3:v4= (2-