CN113248139A

CN113248139A - Optical glass with high photoinduced refractive index change, optical fiber prepared from optical glass, and preparation method and application of optical fiber

Info

Publication number: CN113248139A
Application number: CN202110608661.2A
Authority: CN
Inventors: 张洋; 侯伟杰; 刘娟; 贾金升; 徐宇晗; 刘静波; 孙勇; 刘波; 王一苇; 杨亮亮
Original assignee: China Building Materials Academy CBMA
Current assignee: China Building Materials Academy CBMA
Priority date: 2021-06-01
Filing date: 2021-06-01
Publication date: 2021-08-13
Anticipated expiration: 2041-06-01
Also published as: CN113248139B

Abstract

The invention provides optical glass with high photoinduced refractive index change, an optical fiber prepared from the optical glass, and a preparation method and application of the optical glass, wherein the optical glass comprises the following components in percentage by weight: 55% -60% of silicon dioxide; 15% -20% of aluminum oxide; 5% -10% of magnesium oxide; 0-10% of boron trioxide;5-10% of lead oxide; 0-5% of germanium dioxide; 0-5% of cerium dioxide. The refractive index (n) of the optical glass prepared by the method of the invention_d) Comprises the following steps: 1.53 to 1.58; the material has extremely high light absorption rate in a deep ultraviolet band (namely an ultraviolet laser band), and the spectral transmittance in a 180-300nm band is less than or equal to 30 percent; the spectral transmittance in the range of 400-2000nm is more than or equal to 95 percent; the optical communication band (usually 1310nm or 1550nm) has extremely low absorptivity, namely the spectral transmittance in the 1100-1600nm band is more than or equal to 99 percent; after ultraviolet laser irradiation, the refractive index change reaches (4-8) x 10^‑3。

Description

Optical glass with high photoinduced refractive index change, optical fiber prepared from optical glass, and preparation method and application of optical fiber

Technical Field

The invention relates to the technical field of optical glass, in particular to optical glass with high photoinduced refractive index change, an optical fiber prepared from the optical glass, and a preparation method and application of the optical fiber.

Background

The fiber grating is formed by the technology of ultraviolet laser irradiation or femtosecond laser direct writing and the like on a fiber core of the fiber, when a beam of broadband light is incident into the fiber grating, the periodic structure of the refractive index enables narrow-band light with a certain specific wavelength to be reflected, and the wavelength of the reflected light meets the Bragg scattering condition. Because the variation of grating period or equivalent refractive index can be caused by the variation of temperature, strain, acceleration and other variables, and further the change of the central wavelength of the grating reflected light can be caused, the variation of the parameters of temperature, strain, acceleration and the like in the environment can be obtained by accurately measuring the variation of the central wavelength of the fiber grating reflected light (see fig. 1).

The fiber grating has the remarkable advantages of high sensitivity, high precision, low loss, easiness in distributed measurement, low power consumption, light weight, small diameter and the like, becomes a core device for fiber communication, fiber laser and fiber sensing, is widely applied to the fields of aerospace, ship heavy industry, petroleum power, national defense safety, high-speed rail and rail traffic, bridges, civil engineering and the like, plays an important role in the aspects of sensing control of various high-end equipment, health monitoring of major infrastructure and the like, and is a key technology for realizing photoelectric detection sensing, improving the equipment performance and guaranteeing the safety of a key structure.

According to the working principle of the fiber grating, the refractive index change of the fiber core under the irradiation of ultraviolet laser plays a decisive influence on the testing precision and sensitivity of the fiber grating. Currently, the existing fiber grating sensing technology mainly uses a fiber material with quartz glass as a fiber core. Since the silica glass is prepared by chemical vapor deposition or the like from a single silica material, the intrinsic photoinduced refractive index change is small, about 10^-5An order of magnitude.

In addition, the difference between the softening temperature of the multi-component glass and the softening temperature of the quartz glass is about 1200 ℃, so that the fusion splicing difficulty of the multi-component glass optical fiber and the quartz optical fiber is great in the actual use process, and the application of the multi-component glass optical fiber is restricted.

Disclosure of Invention

In view of the above problems, it is an object of the present invention to provide an optical glass with high photoinduced refractive index variation, an optical fiber prepared from the glass, and a preparation method and application thereof.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the optical glass with high photoinduced refractive index change comprises the following components in percentage by weight: 55% -60% of silicon dioxide; 15% -20% of aluminum oxide; 5% -10% of magnesium oxide; 0-10% of boron trioxide; 5-10% of lead oxide; 0-5% of germanium dioxide; 0-5% of cerium dioxide.

Preferably, the optical glass with high photoinduced refractive index change comprises the following components in percentage by weight: 55% -57% of silicon dioxide; 15% -18% of aluminum oxide; 7 to 10 percent of magnesium oxide; 6-10% of boron trioxide; 8-10% of lead oxide; 3-5% of germanium dioxide; 3-5% of cerium dioxide. Preferably, the glass has higher softening temperature by designing higher contents of aluminum oxide, magnesium oxide and silicon dioxide, and simultaneously, the contents of the boron oxide, the lead oxide, the germanium dioxide and the cerium dioxide are reasonably increased, so that the photoinduced refractive index change performance of the glass can be improved.

Further, in the optical glass with high photoinduced refractive index change, the optical glass can further contain antimony trioxide and/or arsenic trioxide with the total amount of less than 5 wt% per thousand in percentage by weight.

Further, in the aforementioned high-luminous-refractive-index-change optical glass, wherein the optical glass has a property of refractive index (n)_d) Comprises the following steps: 1.53 to 1.58; the linear expansion coefficient is: (60-70). times.10^-7/° c; the glass transition temperature is: 750 ℃ and 800 ℃; the glass softening temperature is: 900 ℃ and 950 ℃.

Further, in the aforementioned high-photorefractive-index-change optical glass, wherein the spectral transmittance (measured by a spectrophotometer for a glass sheet having a thickness of 5 mm) of the optical glass has the following characteristics at different wavelength bands:

(1) the spectral transmittance in the 180-300nm waveband is less than or equal to 30 percent, and the glass has the advantages of extremely high light absorption rate in the deep ultraviolet waveband (namely the ultraviolet laser waveband), and can realize large change of the glass refractive index by improving the absorption of the deep ultraviolet light, namely high intrinsic photoinduced refractive index change.

(2) The spectral transmittance in the range of 400-2000nm is greater than or equal to 95%, wherein the spectral transmittance in the range of 1100-1600nm is greater than or equal to 99%, which aims to have extremely low absorption rate for the optical communication band (usually 1310nm or 1550nm) so as to reduce the optical loss.

Go toIn the optical glass with high photoinduced refractive index change, the refractive index change of the optical glass is (4-8) multiplied by 10 after the optical glass is irradiated by ultraviolet laser^-3In the meantime.

Further, in the aforementioned optical glass with high photorefractive index change, the ultraviolet laser irradiation conditions are as follows: the laser wavelength is 248nm, the pulse width is 10ns, the pulse frequency is 50Hz, the pulse energy is 20mJ, the spot diameter is 5mm, and the irradiation time is 10 min.

The purpose of the invention and the technical problem to be solved can be realized by adopting the following technical scheme. The invention provides a preparation method of optical glass with high photoinduced refractive index change, which comprises the following steps:

1) weighing the raw materials according to the formula ratio, and uniformly mixing to obtain a batch;

2) adding the batch materials into a crucible for melting for multiple times at the temperature of 1200-1300 ℃, wherein the time interval between each time of feeding is 10-30 minutes;

3) after the feeding is finished, heating to 1500-;

4) cooling to 1300-;

5) after homogenization, pouring the glass liquid in a mold to form an optical glass blank;

6) and (3) preserving the formed optical glass blank for 2-3 hours at the temperature of 600-700 ℃, then cutting off the power and annealing to room temperature, and discharging to obtain the optical glass.

The purpose of the invention and the technical problem to be solved can be realized by adopting the following technical scheme. The optical fiber provided by the invention comprises a fiber core and a cladding, wherein the fiber core is made of the optical glass, and the cladding is made of quartz glass.

Further, in the foregoing optical fiber, the optical fiber is a single mode optical fiber or a multimode optical fiber.

Further, in the foregoing optical fiber, a core diameter of the single-mode optical fiber is 8 to 10 μm, and a cladding diameter is 125 ± 5 μm.

Further, in the optical fiber, the diameter of the core of the multimode optical fiber is 50-65 μm, and the diameter of the cladding is 125 ± 5 μm.

The purpose of the invention and the technical problem to be solved can be realized by adopting the following technical scheme. The invention provides a preparation method of an optical fiber, which comprises the following steps:

s1, designing the physical dimensions of a core glass rod and a cladding glass tube according to the specification (the core diameter D1 and the cladding diameter D2) of the optical fiber, wherein the diameter of the core glass rod is D1, the outer diameter of the cladding glass tube is D2, and the inner diameter of the cladding glass tube is D1+ delta D;

s2, weighing and uniformly mixing the raw materials according to the formula, melting the raw materials into optical glass, and processing the optical glass into a fiber core glass rod with the diameter of D1;

s3, processing the quartz glass into a clad glass tube with the outer diameter of D2 and the inner diameter of D1+ delta D;

s4, sealing one end of the cladding glass tube by using a flame processing method;

s5, sleeving the fiber core glass rod in the cladding glass tube to form an optical fiber preform;

s6, the optical fiber prefabricated rod is hung on the optical fiber drawing tower and is evenly drawn into the optical fiber at a drawing temperature.

Further, in the foregoing method for manufacturing an optical fiber, in step S1, the ratio of D2 to D1 is equal to the ratio of D2 to D1.

Further, in the foregoing method for manufacturing an optical fiber, wherein in step S1, Δ D is 0.1 to 0.5 mm.

Further, in the foregoing method for preparing an optical fiber, wherein in step S6, the drawing temperature is 1800-2100 ℃.

Further, in the method for preparing the optical fiber, the numerical aperture of the optical fiber is 0.49-0.63, the fiber loss is 0.5-1.0dB/m, and the tensile strength is 120-.

The purpose of the invention and the technical problem to be solved can be realized by adopting the following technical scheme. The optical fiber sensing element comprises an optical fiber, wherein the optical fiber comprises a fiber core and a cladding, the fiber core is made of the optical glass, the cladding is made of quartz glass, and the fiber core is provided with a grating with a periodic refractive index change.

Further, in the foregoing optical fiber sensing element, the optical fiber sensing element is an optical fiber sensor, an optical fiber laser, or an optical fiber communicator.

After the optical glass and/or the optical fiber prepared by the glass is irradiated by a mask plate and ultraviolet laser or femtosecond laser, a grating with periodic refractive index change is engraved on the fiber core of the optical fiber, and the optical fiber is further applied to optical fiber sensing, optical fiber laser and optical fiber communication.

Compared with the prior art, the invention has the following beneficial effects:

the refractive index (n) of the optical glass of the present invention_d) Comprises the following steps: 1.53 to 1.58; the material has extremely high light absorption rate in a deep ultraviolet band (namely an ultraviolet laser band), and the spectral transmittance in a 180-300nm band is less than or equal to 30 percent; the spectral transmittance in the range of 400-2000nm is more than or equal to 95 percent; the optical communication band (usually 1310nm or 1550nm) has extremely low absorptivity, namely the spectral transmittance in the 1100-1600nm band is more than or equal to 99 percent; after ultraviolet laser irradiation, the refractive index change reaches (4-8) x 10^-3。

The transition temperature of the optical glass is 750-800 ℃ and the softening temperature is 900-950 ℃, so the glass has higher softening point and can be matched with a quartz cladding glass tube to be pulled down at high temperature (1800-2100 ℃) to form an optical fiber, and the optical fiber has a silicate glass core with high photoinduced refractive index change and a quartz glass cladding. Therefore, the optical fiber can be very conveniently fused with a conventional silica optical fiber.

The optical fiber has the numerical aperture of 0.49-0.63 which is far higher than that of a quartz optical fiber by 0.18-0.22, has higher incident light signal collection capacity, has the loss of 0.5-1.0dB/m, has lower loss and higher tensile strength of 120-150kpsi, and is suitable for the fields of short-distance optical fiber sensing and communication or application scenes with higher requirements on strength.

The fiber core of the optical fiber has higher intrinsic photoinduced refractive index change, can realize rapid grating writing through ultraviolet laser or femtosecond laser irradiation, and is easy to prepare into an optical fiber sensor or a high-power optical fiber laser with high sensitivity and high precision. For example, the optical fiber temperature sensor prepared by using the optical glass with high photoinduced refractive index change and the optical fiber as base materials can achieve the temperature measurement accuracy of 0.2-0.3 ℃.

The optical glass or the optical fiber core has good stability of the change of the photoinduced refractive index after the irradiation of ultraviolet laser or femtosecond laser, can not fade in the use process, and can not change the change condition of the photoinduced refractive index after being annealed for 2 hours at the temperature of 300 ℃.

The foregoing is a summary of the present invention, and in order to provide a clear understanding of the technical means of the present invention and to be implemented in accordance with the present specification, the following is a detailed description of the preferred embodiments of the present invention.

Drawings

FIG. 1 is a schematic diagram of a fiber grating in the prior art;

FIG. 2 is a graph of the spectral transmittance of a 5mm thick optical glass sample of example 3 of the present invention;

FIG. 3 is a schematic diagram of a single mode optical fiber according to the present invention;

FIG. 4 is a schematic diagram of the structure of a multimode optical fiber according to the present invention.

Detailed Description

For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.

The following materials or reagents, unless otherwise specified, are all commercially available.

The formulation compositions (in weight percent) of the high-photoinduced refractive index change optical glasses of examples 1-8 of the invention and the optical glasses of comparative examples 1-2 are shown in table 1.

TABLE 1 composition of highly photoinduced refractive index change optical glass (in weight percent)

Examples	1	2	3	4	5	6	7	8	Comparative example 1	Comparative example 2
											Silicon dioxide	55	57	58	60	58.5	54.5	56	57.5	64.5	44.5
Aluminum oxide	20	19	18	16	17	16	18	15	16	16
											Magnesium oxide	10	9	7	7	5	10	8	8	10	10
Boron trioxide	10	6	7	4	1	0	5	7	0	0
											Lead oxide	5	6	7	8	9	10	8	7	0	20
Germanium dioxide	0	1	2	3	4	5	2	3	5	5
											Cerium oxide	0	2	1	2	5	4	3	2	4	4
Antimony trioxide	0	0.2	0.3	0.1	0.4	0.5	0	0.3	0.5	0.5
											Arsenic trioxide	0	0.1	0.1	0.3	0.1	0	0.4	0.2	0	0
Temperature of feed	1350	1350	1350	1350	1350	1350	1350	1350	1350	1350
											Feeding interval	30	30	30	30	30	30	30	30	30	30
Melting temperature	1500	1500	1500	1500	1500	1500	1500	1500	1500	1500
											Settling time	4	4	4	4	4	4	4	4	4	4
Homogenization temperature	1350	1350	1350	1350	1350	1350	1350	1350	1350	1350
											Time of homogenization	2	2	2	2	2	2	2	2	2	2
Annealing temperature	650	650	650	650	650	650	650	650	650	650
											Annealing time	2	2	2	2	2	2	2	2	2	2

Further, weighing the raw materials according to the formula proportion of each component listed in the table 1, and uniformly mixing to obtain a batch; adding the batch materials into a crucible for melting for multiple times at 1350 ℃, wherein the interval time of each charging is 30 minutes; after the charging is finished, heating to 1500 ℃ and clarifying for 4 hours; cooling to 1350 ℃ after clarification, preserving heat for 3 hours and homogenizing; after homogenization, pouring the glass liquid in a mold to form an optical glass blank; keeping the temperature of the formed optical glass blank at 650 ℃ for 2 hours, then cutting off the power and annealing to room temperature, and discharging to obtain the optical glass; the optical glass was then subjected to the main performance tests, the test results of which are shown in table 2.

Wherein, the refractive indexes before and after ultraviolet laser irradiation are tested according to GB/T7962.1-2010; the expansion coefficient, the transition temperature and the softening temperature are tested according to GB/T7962.16-2010; the spectral transmittance is tested according to GB/T7962.12-2010, and the sample is a glass sheet with the thickness of 5 mm; the ultraviolet laser irradiation conditions are that the laser wavelength is 248nm, the pulse width is 10ns, the pulse frequency is 50Hz, the pulse energy is 20mJ, the spot diameter is 5mm, and the irradiation time is 10 min.

TABLE 2 Properties of high-photoinduced-refractive-index-change optical glasses of examples 1 to 8 of the invention and optical glasses of comparative examples 1 to 2

As can be seen from the data in Table 2, the refractive index (n) of the optical glass prepared according to the present invention_d) Comprises the following steps: 1.53 to 1.58; the linear expansion coefficient is: (60-70). times.10^-7/° c; the glass transition temperature is: 750 ℃ and 800 ℃; the glass softening temperature is: 900 ℃ and 950 ℃. The material has extremely high light absorption rate in a deep ultraviolet band (namely an ultraviolet laser band), and the spectral transmittance is less than or equal to 30% in a 180-300nm band; the spectral transmittance within the range of 400-2000nm is more than or equal to 95 percent; the optical communication band (usually 1310nm or 1550nm) has extremely low absorption rate, namely the spectral transmittance at 1100 and 1600nm is more than or equal to 99 percent; the refractive index of the material after ultraviolet laser irradiation changes in4-8)×10^-3In the meantime.

Comparative example 1 compared to example 6, with no lead oxide added, the other components were substantially the same or did not differ significantly in content. As can be seen from the test results, the photo-induced refractive index change of comparative example 1 is much lower than that of example 6, which indicates that lead oxide has a better effect in increasing the photo-induced refractive index change of the glass.

The lead oxide content was further increased in comparative example 2 compared to example 6, and the other component contents were substantially the same or slightly different. From the test results, it can be seen that the light induced refractive index change of comparative example 2 is much higher than that of example 6, but the refractive index and dispersion are high due to the lead oxide content being too high.

The spectral transmittance curve of the 5mm thick optical glass sample of example 3 is shown in fig. 2.

For further understanding, the functions and design principles of the components in the optical glass of the present invention are described as follows:

in the present invention, silica is a main component of the glass-forming skeleton and is a component that plays a major role in the glass skeleton. The content of the silicon dioxide is 55 wt% -60 wt% in percentage by weight. Compared with common glass, the invention has higher content of silicon dioxide, which can reduce the thermal expansion coefficient of the glass and improve the thermal stability, chemical stability, softening temperature, heat resistance, hardness, mechanical strength and the like of the glass. In the glass system of the present invention, when the content of silica is more than 60 wt%, the difficulty of melting increases. Below 55 wt%, the refractive index of the glass is greatly increased beyond the refractive index and numerical aperture requirements required by the present invention.

The aluminum oxide is mainly used for partially replacing silicon dioxide, and can obviously improve the chemical stability of the glass and improve the strength and the softening temperature. The high-strength glass contains 15-20 wt% of aluminum oxide, is higher than common glass and is equivalent to high-strength glass, and aims to further improve the stability and softening temperature of the glass so as to be matched with a quartz glass cladding and meet the process requirement of high-temperature wire drawing. If the content of the aluminum oxide exceeds 20 wt%, the glass melting temperature requirement is higher, the difficulty is high, and the defects such as stones in the glass are increased; if the content of alumina is less than 15 wt%, the softening temperature of the glass is lowered and the drawing temperature matching with the quartz glass is deteriorated.

The magnesium oxide is a network outer body and plays a role in improving parameters such as glass melting characteristics, expansion coefficients and the like. According to experimental research, the content of the magnesium oxide in the invention is 5-10 wt%. If the content of magnesium oxide exceeds 10 wt%, the softening temperature of the glass is lowered and the drawing temperature matching with the silica glass is deteriorated. If the content of the magnesium oxide is less than 5 wt%, the melting temperature requirement of the glass is higher, the difficulty is high, and the defects of stones and the like in the glass are increased.

The boron trioxide is not only an oxide formed by glass, but also a component forming a glass skeleton, and is a cosolvent for reducing the melting viscosity of the glass. In the invention, the boron trioxide also plays the key roles of improving the photoinduced refractive index change of the glass and reducing the dispersion. Boron oxygen trihedron [ BO₃]And boron-oxygen tetrahedron [ BO₄]Boron may be trihedral [ BO ] under different conditions as structural elements₃]Or boron-oxygen tetrahedron [ BO₄]In the presence of B, it is difficult to form boron-oxygen tetrahedron under high-temperature melting conditions, but B is present only in the form of trihedron under certain conditions at low temperature³⁺There is a tendency to abstract free oxygen to form tetrahedra, making the structure compact and increasing the low temperature viscosity of the glass, but it has the characteristics of decreasing the viscosity of the glass at high temperature and increasing the viscosity of the glass at low temperature. Under the action of ultraviolet laser irradiation or femtosecond laser irradiation, the boron-oxygen trihedron [ BO ] in the glass₃]And boron-oxygen tetrahedron [ BO₄]The transformation of configuration at the microscopic level is the main cause of the change in the light-induced refractive index of the glass. According to experimental research, the content of boron trioxide is 0-10 wt% in percentage by weight. If the content exceeds 10 wt%, the softening temperature of the glass is lowered and the drawing temperature matching with the silica glass is deteriorated.

The lead oxide plays an important role in improving the refractive index of the glass, adjusting the thermal property of the glass, reducing the melting temperature of the glass and improving the internal quality of the glass. In addition, lead oxide is also the key to improving the light induced refractive index change of the glass in the present invention. This is because only 4 electrons exist in the outermost electron shell of the Pb atom, and the absorption of the electrons easily occurs in energy level transition. Meanwhile, Pb2+ and Pb4+ are subjected to valence state conversion under the action of ultraviolet laser irradiation, so that the potential distribution in a micro-light region is changed, the attraction force to O2-is changed, the microstructure of the glass is changed, and the photoinduced refractive index change is formed. According to experimental research, the content of the lead oxide is 5-10 wt% in percentage by weight. If the content exceeds 10 wt%, the softening temperature of the glass is lowered and the drawing temperature matching with the silica glass is deteriorated. If the content is less than 5 wt%, the effect of improving the change of the glass in the light-induced refractive index is not good.

Germanium dioxide is also a network former, and as Ge and Si are elements in the same group and the electronic structure of the outer layer is the same, Ge and Si can be substituted into the glass network, and after the irradiation of ultraviolet laser or femtosecond laser, the change of the local microstructure forms the refractive index change. In the present invention, the content thereof is 0 to 5 wt%. If the content of germanium dioxide exceeds 5%, it will cause difficulty in melting the glass, and germanium dioxide is expensive, so that germanium dioxide is not suitable for being introduced in a large amount into the glass.

The content of ceria is 0-5 wt%, which in the present invention functions as: the ultraviolet ray absorption of the outer layer electrons can improve the photoinduced refractive index change of the glass, and the irradiation resistance of the glass can be improved. If the content is more than 5 wt%, the spectral absorption of the glass decreases, and the loss of the glass optical fiber increases.

In addition, in order to improve the internal quality of the glass, antimony trioxide and/or arsenic trioxide can be introduced into the glass component, wherein the antimony trioxide and/or arsenic trioxide is used as a clarifying agent and is helpful for discharging bubbles in the glass melting process so as to improve the internal quality of the optical glass. If the amount exceeds 5 wt%, the content of antimony trioxide and/or arsenic trioxide is too high, which may result in deterioration of the optical properties of the glass. Antimony trioxide and arsenic trioxide have the same effect, and the effect is the same when the antimony trioxide and the arsenic trioxide are added singly or in combination. However, if it is considered from the viewpoint of environmental protection, it is preferable to add antimony trioxide alone.

The "high photorefractive index change" mentioned above refers to high photosensitivity, i.e. the refractive index of the optical glass changes under deep ultraviolet irradiation conditions. Are well known in the art.

The invention also provides an optical fiber prepared from the optical glass and a preparation method thereof.

As shown in fig. 3 and 4, the optical fiber includes a core 1 and a cladding 2, wherein the material of the core 1 is the above optical glass (for example, embodiments 1 to 8), and the material of the cladding 2 is silica glass. The optical fiber sensing element may comprise a single or a plurality of optical fibers, typically a single optical fiber.

If the optical fiber is a single-mode optical fiber, the diameter of a fiber core of the optical fiber is 8-10 mu m, and the diameter of a cladding of the optical fiber is 125 +/-5 mu m.

If the optical fiber is a multimode optical fiber, the diameter of the core of the optical fiber is 50-65 μm, and the diameter of the cladding of the optical fiber is 125 +/-5 μm.

In addition, in order to protect the surface of the optical fiber from being scratched by moisture and external force, reduce the microbend additional loss function of the optical fiber, and the like, the outer surface of the optical fiber may be further provided with an organic protective layer.

Further, the preparation method of the optical fiber comprises the following steps:

(1) designing the physical dimensions of a core glass rod and a cladding glass tube according to the optical fiber specifications (the core diameter D1 and the cladding diameter D2), wherein the diameter of the core glass rod is D1, the outer diameter of the cladding glass tube is D2, and the inner diameter of the cladding glass tube is D1+ delta D;

(2) weighing according to the formula, uniformly mixing, melting into optical glass, and processing into a fiber core glass rod with the diameter of D1;

(3) processing quartz glass into a cladding glass tube with the outer diameter of D2 and the inner diameter of D1+ delta D;

(4) sealing one end of the cladding glass tube by using a flame processing method;

(5) sleeving a fiber core glass rod in a cladding glass tube to form an optical fiber prefabricated rod;

(6) and hanging the optical fiber preform on an optical fiber drawing tower, and uniformly drawing the optical fiber preform into an optical fiber at a certain drawing temperature.

In specific implementation, the ratio of D2 to D1 is equal to the ratio of D2 to D1.

In specific implementation, the range of the delta D is 0.1-0.5 mm.

In specific implementation, the temperature of the wire drawing is 1800-2100 ℃.

Furthermore, the numerical aperture of the optical fiber is 0.49-0.63, and the loss of the optical fiber is 0.5-1.0 dB/m.

According to actual needs, the method can also comprise the step of coating the outer surface of the optical fiber with an organic protective layer of acrylate, carbonate or polyurethane.

The optical glass provided by the invention has the characteristic of high softening temperature (examples 1-8), the drawing temperature of the optical glass is between 1100 and 1300 ℃, the drawing temperature difference with the ordinary glass (700 and 800 ℃) is small, and the drawing forming together with the quartz glass cladding can be realized through the adjustment of the drawing process.

The properties of the optical fibers prepared using examples 1 to 8 (examples 9 to 16) and comparative examples 1 to 2 (comparative examples 3 to 4) according to the above procedure are shown in Table 3.

As can be seen from the data in Table 3, the optical fiber prepared by using the optical glass with high photoinduced refractive index change (examples 1-8) provided by the invention has good fiber forming performance and can be prepared into a single-mode or multi-mode optical fiber; when the optical fiber is drawn by matching the optical glass with high photoinduced refractive index change and the quartz glass, the drawing temperature is usually higher at 1800-2100 ℃, the numerical aperture of the optical fiber is 0.49-0.63, the optical fiber loss is 0.5-1.0dB/m, and the high tensile strength (120-150kpsi) can meet the application requirement of optical fiber sensing;

comparative example 3 is an optical fiber prepared by using the glass material described in comparative example 1 as a fiber core, and although the optical fiber can also be used for optical fiber sensing, the refractive index modulation is small in the ultraviolet grating writing process of the prepared optical fiber because the value of the change of the photoinduced refractive index of comparative example 1 is small, the optical fiber sensing performance is not good, and the application requirement of high-precision optical fiber sensing cannot be met. Comparative example 4 is an optical fiber prepared by using the glass material described in comparative example 2 as a core, and the temperature measurement accuracy is 0.08, but the loss is too high to be used as an optical fiber sensing material.

The optical glass and the optical fiber prepared from the optical glass have the characteristics of high photoinduced refractive index change and the like, so that gratings with periodic refractive index change can be inscribed on the fiber core of the optical fiber after being irradiated by a mask plate and ultraviolet laser or femtosecond laser, and the optical glass and the optical fiber prepared from the optical glass are further applied to the fields of optical fiber sensing, optical fiber laser, optical fiber communication and the like.

Taking the preparation of the optical fiber temperature measuring sensor as an example, the preparation process is as follows: taking 2 meters of long optical fibers (examples 9-16 and comparative example 1) and placing one optical fiber in the existing grating writing device, wherein the grating writing position is selected as the central area of the optical fiber; placing the mask plate at a position 25mm away from the optical fiber, and exposing for 10 seconds by using an excimer laser beam with the width of 12 mm; the period of the change of the refractive index of the grating is 0.1 mu m, and the total length of the grating is 1 mm; the optical fiber with the carved grating is connected with a 1054nm laser light source, a demodulator, a computer and the like to prepare an optical fiber temperature measuring sensor system, and the data in the table 3 show that the temperature measuring precision corresponding to the embodiments 9-16 can reach 0.2-0.3 ℃, which is far better than that corresponding to the comparative examples 3-4.

In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

The recitation of numerical ranges herein includes all numbers subsumed within that range and includes any two numbers subsumed within that range. Different values of the same index appearing in all embodiments of the invention can be combined arbitrarily to form a range value.

The features of the invention claimed and/or described in the specification may be combined, and are not limited to the combinations set forth in the claims by the recitations therein. The technical solutions obtained by combining the technical features in the claims and/or the specification also belong to the scope of the present invention.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiment according to the technical spirit of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. The optical glass with high photoinduced refractive index change is characterized by comprising the following components in percentage by weight: 55% -60% of silicon dioxide; 15% -20% of aluminum oxide; 5% -10% of magnesium oxide; 0-10% of boron trioxide; 5-10% of lead oxide; 0-5% of germanium dioxide; 0-5% of cerium dioxide.

2. The high photorefractive index change optical glass according to claim 1, wherein the optical glass may further comprise antimony trioxide and/or arsenic trioxide in a total amount of less than 5% by weight.

3. The high-photorefractive-index-change optical glass according to claim 1, wherein said optical glass has the property of refractive index (n)_d) Comprises the following steps: 1.53 to 1.58; the linear expansion coefficient is: (60-70). times.10^-7/° c; the glass transition temperature is: 750 ℃ and 800 ℃; the glass softening temperature is: 900 ℃ and 950 ℃;

the optical glass has the following characteristics of spectral transmittance in different wave bands:

(1) the spectral transmittance is less than or equal to 30 percent in the 180-plus-300 nm wave band;

(2) the spectral transmittance in the range of 400 plus 2000nm is more than or equal to 95 percent, wherein the spectral transmittance in the range of 1100 plus 1600nm is more than or equal to 99 percent;

after the optical glass is irradiated by ultraviolet laser, the refractive index change of the optical glass is (4-8) multiplied by 10^-3To (c) to (d); the ultraviolet laser irradiation conditions are as follows: the laser wavelength is 248nm, the pulse width is 10ns, the pulse frequency is 50Hz, the pulse energy is 20mJ, the spot diameter is 5mm, and the irradiation time is 10 min.

4. A method for producing a high-luminous-refractive-index-change optical glass according to any one of claims 1 to 3, comprising the steps of:

3) after the feeding is finished, heating to 1500-;

4) cooling to 1300-;

5. An optical fiber comprising a core and a cladding, wherein the core is made of the optical glass according to any one of claims 1 to 3, and the cladding is made of silica glass.

6. The optical fiber of claim 5, wherein the optical fiber is a single mode fiber or a multimode fiber; the diameter of a fiber core of the single-mode optical fiber is 8-10 mu m, and the diameter of a cladding is 125 +/-5 mu m; the diameter of the core of the multimode fiber is 50-65 μm, and the diameter of the cladding is 125 +/-5 μm.

7. A method of making an optical fiber according to claim 5 or 6, comprising the steps of:

s1, designing the physical size of a core glass rod and a cladding glass tube according to the core diameter D1 and the cladding diameter D2 of the optical fiber, wherein the diameter of the core glass rod is D1, the outer diameter of the cladding glass tube is D2, and the inner diameter of the cladding glass tube is D1+ delta D;

s3, processing the deep ultraviolet transmitting glass into a cladding glass tube with the outer diameter of D2 and the inner diameter of D1+ delta D;

s4, sleeving the fiber core glass rod in the cladding glass tube to form an optical fiber preform;

s5, the optical fiber prefabricated rod is hung on the optical fiber drawing tower and is evenly drawn into the optical fiber at a drawing temperature.

8. The method of claim 7, wherein in step S1, the ratio of D2 to D1 is equal to the ratio of D2 to D1; the delta D is 0.1-0.5 mm; in the step S6, the drawing temperature is 1800-2100 ℃; the optical fiber has a numerical aperture of 0.49-0.63, a fiber loss of 0.5-1.0dB/m, and a tensile strength of 120-150 kpsi.

9. An optical fiber sensing element comprising an optical fiber, wherein the optical fiber comprises a core and a cladding, the core is made of the optical glass according to any one of claims 1 to 3, the cladding is made of silica glass, and the core is provided with a grating with a periodic refractive index change.

10. The fiber optic sensing element of claim 9, wherein the fiber optic sensing element is a fiber optic sensor, a fiber laser, or a fiber optic communicator.