CN118610867A - Bismuth-doped optical fiber with E and S band extension and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of optical fibers and discloses a E, S-band expanded bismuth-doped optical fiber and a preparation method thereof. The optical fiber provided by the invention comprises a fiber core and a cladding, wherein the fiber core is formed by a silicon dioxide material doped with bismuth element and co-doped element, and the co-doped element is one or two elements of phosphorus and germanium; the optical fiber has a fluorescence light emitting amplification broadband in a wavelength range of 1360-1530 nm. The invention combines the improved chemical vapor deposition method MCVD and the liquid phase doping method for preparing the optical fiber. The invention can realize the expansion and amplification of E+S wave band, and the bismuth-doped optical fiber with high quality prepared by the invention has wide application prospect in the field of E+S wave band communication transmission optical amplification.

Description

Bismuth-doped optical fiber with E and S band extension and preparation method thereof

Technical Field

The present invention belongs to the technical field of optical fibers, and more specifically, relates to an E and S band extended bismuth-doped optical fiber and a preparation method thereof.

Background Art

Traditional erbium doped fiber amplifiers (EDFA) mainly work in the C+L (C band: conventional band, wavelength range 1530 ~ 1565nm; L band: long wavelength band, wavelength range 1565 ~ 1625nm) frequency band, which cannot meet the growing demand for fiber capacity. Therefore, it is urgent to research and develop fiber amplifiers outside the C+L band. At present, some rare earth doped fiber amplifiers have been developed, such as praseodymium doped, neodymium doped, and thulium doped fiber amplifiers, but these fiber amplifiers have the problem of narrow gain bandwidth. In addition, Raman fiber amplifiers are currently the only fiber amplifiers that can achieve ultra-wideband full-range amplification from 1270 to 1660nm, but their disadvantages include complex structure, high pump power, the need for multiple pump sources to work simultaneously, and high cost.

Bismuth (Bi)-doped silica (SiO ₂ )-based optical fibers have broadband near-infrared (NIR) luminescence properties spanning the O-band (original band, wavelength range 1260-1360nm), E-band (extended wavelength band, wavelength range 1360-1460nm) and even the U-band (ultra-long wavelength band, wavelength range 1625-1675nm), making Bismuth a promising dopant for developing amplifiers in the above-mentioned bands.

Chinese patent CN105467511A proposes to use ALD technology to prepare a Bi/Er or Bi/Er/Al co-doped silica fiber, which can achieve ultra-wideband amplification in the 1000-1380nm and 1450-1800nm bands. Chinese patent CN116500720A uses ALD technology and MCVD technology to prepare bismuth-doped silica fiber, and the fiber gain in the 1260-1460nm band is greater than 15dB. Chinese patent CN 116679373 A discloses an L+ and L+U band active silica fiber and its preparation method. The fiber core is doped with bismuth and other ions, which can expand the U band bandwidth to 1680nm.

However, there are few studies on bismuth-doped optical fibers in the E+S band worldwide, especially in China. Therefore, studying E+S band extended highly bismuth-doped optical fibers not only has important scientific significance, but also has broad application prospects.

Summary of the invention

The object of the present invention is to provide an E, S band extended bismuth-doped optical fiber and a preparation method thereof, so as to achieve extended amplification of the E+S band.

The invention provides an E and S band extended bismuth-doped optical fiber, comprising: a fiber core and a cladding; the fiber core is composed of a silicon dioxide material doped with bismuth and a co-doped element, and the co-doped element is one or two elements of phosphorus and germanium; the optical fiber has a fluorescent luminescence amplification broadband within a wavelength range of 1360 to 1530 nm.

Preferably, the concentration range of _Bi2O3 is 100-2000ppm; when the core is doped with phosphorus, the concentration range _{of P2O5 is} 100-15000ppm; when the core is doped with germanium, the concentration range of _GeO2 is 500-10000ppm.

Preferably, the diameter of the core is 4-10 μm, and the diameter of the cladding is 120±5 μm.

Preferably, the cladding is made of fluorine-containing silicon dioxide material.

Preferably, the optical fiber forms a bismuth silicon active center BAC-Si and a bismuth phosphorus active center BAC-P, or the optical fiber forms a bismuth silicon active center BAC-Si and a bismuth germanium active center BAC-Ge, or the optical fiber forms a bismuth silicon active center BAC-Si, a bismuth phosphorus active center BAC-P and a bismuth germanium active center BAC-Ge; the emission peak width of the bismuth silicon active center BAC-Si is 1430nm±10nm, the emission peak width of the bismuth phosphorus active center BAC-P is 1310nm±100nm, and the emission peak width of the bismuth germanium active center BAC-Ge is 1600nm±200nm.

On the other hand, the present invention provides a method for preparing E and S band extended bismuth-doped optical fiber, which combines improved chemical vapor deposition (MCVD) and liquid phase doping to prepare the optical fiber, and dopes bismuth and co-doping elements into the core of the optical fiber, so that the optical fiber has a wide band of fluorescent luminescence amplification in the wavelength range of 1360 to 1530 nm; the co-doping elements are one or two elements of phosphorus and germanium.

Preferably, the preparation of optical fiber by combining improved chemical vapor deposition method MCVD and liquid phase doping method comprises the following steps: performing cladding deposition; passing a loose layer of silica containing co-doped elements to perform core deposition to obtain a loose powder structure; pouring a standard solution containing bismuth element into the loose powder structure and fully soaking it to obtain a core doped with bismuth element and co-doped elements; performing rod shrinking and drawing to obtain E and S band extended bismuth-doped optical fiber.

Preferably, a mixed gas of silicon tetrachloride, fluoride and oxygen is introduced into the pure quartz reaction tube to perform the cladding deposition; and before performing the rod shrinking and wire drawing, the method further includes: drying the soaked reaction tube.

Preferably, in the prepared optical fiber _, the concentration range of _Bi2O3 is 100-2000ppm; when the core is doped with phosphorus, the concentration range of _P2O5 is _100-15000ppm ; when the core is doped with germanium, the concentration range of _GeO2 is 500-10000ppm.

Preferably, the diameter of the core of the prepared optical fiber is 4-10 μm, and the diameter of the cladding is 120±5 μm.

One or more technical solutions provided in the present invention have at least the following technical effects or advantages:

(1) The core of the E and S band extended bismuth-doped optical fiber provided by the present invention is composed of a silicon dioxide material doped with bismuth and a co-doping element, wherein the co-doping element is one or two elements of phosphorus and germanium; the doping design of the core of the present invention can form a plurality of different bismuth-related active centers (BACs), and based on the emission broad peaks corresponding to the plurality of active centers, by controlling the content of the doping elements, the optical fiber can have a fluorescence luminescence amplification broadband within the wavelength range of 1360 to 1530 nm (i.e., E+S band; E band: extended wavelength band, wavelength range 1360-1460 nm; S band: short wave band, wavelength range 1460-1530 nm), that is, the present invention can expand the BACs emission broad peak to the 1360-1530 nm band, thereby realizing the extended amplification of the E+S band.

(2) The present invention combines the improved chemical vapor deposition method (MCVD) and the liquid phase doping method to prepare optical fiber, which can better control the doping content of each element in the optical fiber, especially overcome the problem of easy volatilization of bismuth ions in the traditional preparation method, which is conducive to obtaining the target concentration of bismuth ions, and then preparing high-quality bismuth-doped optical fiber. It has broad application prospects in the field of E+S band communication transmission optical amplification, and can be applied to high-efficiency optical amplifiers and lasers, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the energy levels of BAC-P, BAC-Ge, and BAC-Si;

FIG2 is a fluorescence luminescence amplification spectrum of an E and S band extended bismuth-doped optical fiber provided in Example 1 of the present invention;

FIG3 is a fluorescence luminescence amplification spectrum of an E and S band extended bismuth-doped optical fiber provided in Example 2 of the present invention;

FIG. 4 is a fluorescence luminescence amplified spectrum of an E and S band extended bismuth-doped optical fiber provided in Example 3 of the present invention.

DETAILED DESCRIPTION

In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

In a first aspect, the present invention provides an E and S band extended bismuth-doped optical fiber, comprising: a core and a cladding; the core is composed of a silica material doped with bismuth and a co-doped element, and the co-doped element is one or two elements of phosphorus and germanium; the optical fiber has a fluorescent luminescence amplification broadband in the wavelength range of 1360 to 1530 nm.

Wherein, the concentration range _{of Bi2O3} is 100-2000ppm; when the core is doped with phosphorus, the concentration range of _P2O5 is _100-15000ppm ; when the core is doped with germanium, the concentration range of _GeO2 is 500-10000ppm.

The diameter of the fiber core is 4-10 μm, the diameter of the cladding is 120±5 μm, and the cladding is made of fluorine-containing silicon dioxide material.

The doping design of the fiber core of the present invention can form multiple different bismuth-related active centers (BACs), for example:

(1) The optical fiber forms a bismuth silicon active center BAC-Si and a bismuth phosphorus active center BAC-P;

(2) The optical fiber forms a bismuth silicon active center BAC-Si and a bismuth germanium active center BAC-Ge;

(3) The optical fiber forms bismuth silicon active centers BAC-Si, bismuth phosphorus active centers BAC-P, and bismuth germanium active centers BAC-Ge.

Among them, the emission peak of the bismuth silicon active center BAC-Si is around 1430nm (specifically 1430nm±10nm), the emission peak of the bismuth phosphorus active center BAC-P is around 1310nm (specifically 1310nm±100nm), and the emission peak of the bismuth germanium active center BAC-Ge is around 1600nm (specifically 1600nm±200nm).

The present invention can form the above three active centers by co-doping elements of phosphorus and/or germanium. By adjusting the doping content of phosphorus and/or germanium, the above three active centers will shift to different degrees according to the doping content of the respective elements. By exciting the three active centers with a pump, light fluorescence emission in the wavelength range of 1360 to 1530 nm can be achieved.

The principle of the present invention is further described below.

The principle of the present invention includes: the present invention uses phosphorus and germanium as co-dopants for bismuth, and bismuth ions and their related matrix materials form bismuth-related active centers (BACs): BAC-Ge, BAC-P, BAC-Si. Referring to Figure 1, for the energy level transition of BAC-P, under the action of pump light of 808nm, 1240nm, 1270nm or 1310nm, the ground state particles are excited to the upper energy level ES2, and then undergo a non-radiative transition to the metastable state ES1, and finally produce a near-infrared emission corresponding to around 1310nm (±100nm). Similarly, for the energy level transition of BAC-Si, under the action of pump light, the ground state particles are excited to the upper energy level ES2, and then undergo a non-radiative transition to the metastable state ES1, and finally produce a near-infrared emission corresponding to around 1430nm (±10nm). For the energy level transition of BAC-Ge, under the action of pump light, the ground state particles are excited to the upper energy level ES2, and then undergo a non-radiative transition to the metastable state ES1, and finally produce near-infrared emission corresponding to around 1600nm (±200nm). The emission broad peaks of BAC-P (1310±100nm) and BAC-Ge (1600±200nm) are recombined and fitted with the emission broad peak of BAC-Si located around 1430nm (±10nm). By controlling the content of P and Ge, the fluorescence luminescence effect in the range of 1360-1530nm can be achieved based on BACs.

It should be noted that the emission peak of the above BACs is not a peak emission at a specific wavelength, but a gentle broad emission peak. For example, the emission intensity of the broad emission peak of BAC-Si is the same within the wavelength range of 1430nm±10nm, and their central emission wavelength will also change with the content. Among them, although the emission peak of BAC-P is near 1310nm, which is more beneficial to the fluorescence emission of the O band, the emission peak of BAC-P is close to BAC-Si near 1430nm. Therefore, by controlling the content of P, it can not only excite the broad emission peak of BAC-Si near 1430nm (±10nm), but also avoid the situation that the band is shifted to the left to the O band due to a large amount of P doping, and the broad emission peak of BAC-Ge is near 1600nm (±200nm). On the whole, the present invention can expand its BACs emission broad peak to the 1360-1530nm band by controlling the content of P and Ge, and realize the expansion and amplification of the E+S band.

Corresponding to the above-mentioned E and S band extended bismuth-doped optical fiber, the present invention also provides a method for preparing the above-mentioned optical fiber, which is specifically described as follows.

In a second aspect, the present invention provides a method for preparing E and S band extended bismuth-doped optical fiber, which combines modified chemical vapor deposition (MCVD) and liquid phase doping to prepare the optical fiber, and dopes bismuth and co-doping elements into the core of the optical fiber, so that the optical fiber has a wide band of fluorescent luminescence amplification in the wavelength range of 1360 to 1530 nm; the co-doping elements are one or two elements of phosphorus and germanium.

The method mainly comprises the following steps: performing cladding deposition; introducing a loose layer of silicon dioxide containing a co-doped element to perform fiber core deposition to obtain a loose powder structure; pouring a standard solution containing a bismuth element into the loose powder structure and fully soaking the solution to obtain a fiber core doped with bismuth element and the co-doped element; and performing rod shrinking and drawing to obtain an E and S band extended bismuth-doped optical fiber.

In addition, before the rod shrinking and wire drawing, the method may further include: drying the soaked reaction tube.

In the prepared optical fiber _, the concentration range of _Bi2O3 is 100-2000ppm; when the core is doped with phosphorus, the concentration range of _P2O5 is 100-15000ppm; when the core is doped with germanium, the concentration range of _GeO2 is 500-10000ppm. The diameter of the core is 4-10μm, _and the diameter of the cladding is 120±5μm.

The following is a further explanation in conjunction with the relevant processes.

A method for preparing an E and S band extended bismuth-doped optical fiber comprises the following steps:

(1) Cladding deposition: A mixture of silicon tetrachloride, fluoride (e.g., silicon tetrafluoride) and oxygen is introduced into a pure quartz reaction tube to deposit a cladding layer, so that the refractive index of the cladding layer is slightly lower than that of quartz or is equivalent to that of quartz.

(2) Loose layer deposition: A loose layer of silicon dioxide containing co-doped elements (including phosphorus and/or germanium) is introduced into the reaction tube for core deposition to obtain a loose powder structure.

(3) Liquid phase doping: first prepare a high-purity standard solution containing bismuth, then pour the standard solution into the loose powder structure, place it on a solution immersion rotating device, and fully immerse it to obtain a fiber core doped with bismuth and the co-doped element.

(4) Drying: First dry with nitrogen, then place the reaction tube on a lathe and dry with chlorine gas several times.

(5) Melting and shrinking the core rod into a rod: The soaked reaction tube is put back into the lathe, the fiber core is first vitrified into a transparent hollow rod, and finally the reaction tube (including the cladding and core layer) is shrunk along the axial direction to obtain a solid core rod;

(6) Wire drawing: The solid core rod is processed and finally drawn and coated to form a bismuth-doped optical fiber.

In summary, Example 2 is based on the MCVD process and liquid phase doping technology. By introducing phosphorus and/or germanium as co-dopants of bismuth in the loose layer and adjusting the doping amount of phosphorus and/or germanium, bismuth ions and their related matrix materials form bismuth-related active centers (BACs): BAC-Ge, BAC-P, BAC-Si, and then the working bandwidth of bismuth is regulated to achieve the expansion of the gain bandwidth of bismuth to the E+S band, and a broadband bismuth-doped optical fiber in the communication band range of 1360 to 1530 nm is prepared.

Three specific embodiments are given below for illustration.

Embodiment 1:

Embodiment 1 provides an E and S band extended bismuth-doped optical fiber, comprising a core and a cladding, wherein the core is composed of a silica material doped with bismuth and phosphorus elements, and the cladding is composed of a fluorine-containing silica material. The concentration of Bi ₂ O ₃ in the core is 200 ppm, the concentration of P ₂ O ₅ is 5000 ppm, the diameter of the core is 9.3 μm, and the diameter of the cladding is 124.0 μm.

When preparing the optical fiber as described in Example 1, a cladding is deposited, a loose layer of silica containing phosphorus oxychloride is deposited (i.e., a loose powdery structure is obtained), the quartz tube containing the loose layer is immersed in a standard solution containing bismuth, and after drying, it is connected to a machine tool and melted into a rod at high temperature to obtain a bismuth-phosphorus co-doped optical fiber preform rod, which is placed in a drawing tower for drawing to produce a bismuth-phosphorus co-doped active quartz optical fiber in the E+S band.

The optical fiber provided in Example 1, under the pumping condition of a 1240 nm laser diode (LD), has a fluorescence amplification spectrum as shown in FIG2 .

Embodiment 2:

Embodiment 2 provides an E and S band extended bismuth-doped optical fiber, comprising a core and a cladding, wherein the core is composed of a silica material doped with bismuth and germanium elements, and the cladding is composed of a fluorine-containing silica material. The concentration of Bi ₂ O ₃ in the core is 500 ppm, the concentration of GeO ₂ is 8000 ppm, the diameter of the core is 10 μm, and the diameter of the cladding is 120.5 μm.

When preparing the optical fiber as described in Example 2, a cladding is deposited, a loose layer of silica containing germanium tetrachloride is deposited, and the quartz tube containing the loose layer is immersed in a standard solution containing bismuth. After drying, it is connected to a machine tool and melted into a rod at high temperature to obtain a bismuth-germanium co-doped optical fiber preform rod, which is placed in a drawing tower for drawing to produce a bismuth-germanium co-doped active quartz optical fiber in the E+S band.

The optical fiber provided in Example 2, under the pumping condition of 1240nm LD, has a fluorescence amplification spectrum as shown in FIG3 .

Embodiment 3:

Embodiment 3 provides _an E and S band extended bismuth-doped optical fiber, comprising a core and a cladding, wherein the core is composed of a silica material doped with bismuth, phosphorus and germanium elements, and the cladding is composed of a fluorine-containing silica material. The concentration of _Bi2O3 in the core is 200ppm, the concentration of _P2O5 is 500ppm, the concentration of _GeO2 is 3000ppm, the diameter of the core is 11.2μm, _and the diameter of the cladding is 125.2μm.

When preparing the optical fiber as described in Example 3, a cladding is deposited, a loose layer of silica containing phosphorus oxychloride and germanium tetrachloride is deposited, the quartz tube containing the loose layer is immersed in a standard solution containing bismuth, and after drying, it is connected to a machine tool for high-temperature melting and shrinking into a rod to obtain a bismuth-phosphorus-germanium co-doped optical fiber preform rod, which is placed in a drawing tower for drawing to produce a bismuth-phosphorus-germanium co-doped active quartz optical fiber in the E+S band.

The optical fiber provided in Example 3, under the pumping condition of 1240nm LD, has a fluorescence amplification spectrum as shown in FIG4 .

Table 1 Related parameters of Examples 1 to 3

The relevant parameters of Examples 1 to 3 are shown in Table 1. It can be seen from the fluorescence amplification spectrum that the emission wavelengths of the fluorescence amplification spectra of Examples 1 to 3 are all covered within the wavelength range of 1360 to 1530 nm, and can be amplified in the E and S bands. That is, the optical fiber provided by the present invention has a wide bandwidth of fluorescence amplification in the E and S bands. Referring to Example 1, the fluorescence emission intensity of the optical fiber provided by the present invention reaches -19.2 dBm at 1450 nm, and has good performance, and can be applied to high-efficiency optical amplifiers and lasers that work outside the currently used C+L band (1530 to 1625 nm).

Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims (10)

1. An E and S band extended bismuth-doped optical fiber, characterized in that it comprises: a core and a cladding; the core is composed of a silicon dioxide material doped with bismuth and a co-doped element, and the co-doped element is one or two elements of phosphorus and germanium; the optical fiber has a fluorescent luminescence amplification broadband in the wavelength range of 1360 to 1530 nm. 2. The E and S band extended bismuth-doped optical fiber according to claim 1, characterized in that the concentration range of _Bi2O3 is _100-2000ppm ; when the core is doped with phosphorus, the concentration range of _P2O5 is _100-15000ppm ; when the core is doped with germanium, the concentration range of _GeO2 is 500-10000ppm. 3. The E and S band extended bismuth-doped optical fiber according to claim 1, characterized in that the diameter of the core is 4 to 10 μm, and the diameter of the cladding is 120±5 μm. 4. The E and S band extended bismuth-doped optical fiber according to claim 1, characterized in that the cladding is composed of fluorine-containing silica material. 5. The E, S band extended bismuth-doped optical fiber according to claim 1, characterized in that the optical fiber forms a bismuth silicon active center BAC-Si and a bismuth phosphorus active center BAC-P, or the optical fiber forms a bismuth silicon active center BAC-Si and a bismuth germanium active center BAC-Ge, or the optical fiber forms a bismuth silicon active center BAC-Si, a bismuth phosphorus active center BAC-P and a bismuth germanium active center BAC-Ge; the emission width peak of the bismuth silicon active center BAC-Si is 1430nm±10nm, the emission width peak of the bismuth phosphorus active center BAC-P is 1310nm±100nm, and the emission width peak of the bismuth germanium active center BAC-Ge is 1600nm±200nm. 6. A method for preparing E and S band extended bismuth-doped optical fiber, characterized in that the optical fiber is prepared by combining improved chemical vapor deposition (MCVD) and liquid phase doping, and bismuth and co-doping elements are doped into the core of the optical fiber so that the optical fiber has a wide-band fluorescence luminescence amplification within the wavelength range of 1360 to 1530 nm; the co-doping elements are one or two elements of phosphorus and germanium. 7. The method for preparing bismuth-doped optical fiber with E and S band extension according to claim 6 is characterized in that the preparation of optical fiber by combining improved chemical vapor deposition method MCVD and liquid phase doping method comprises the following steps: performing cladding deposition; passing a loose layer of silicon dioxide containing co-doped elements to perform core deposition to obtain a loose powder structure; pouring a standard solution containing bismuth element into the loose powder structure and fully soaking it to obtain a core doped with bismuth element and co-doped element; performing rod shrinking and drawing to obtain bismuth-doped optical fiber with E and S band extension. 8. The method for preparing E and S band extended bismuth-doped optical fiber according to claim 7 is characterized in that a mixed gas of silicon tetrachloride, fluoride and oxygen is introduced into the pure quartz reaction tube to perform the cladding deposition; and before performing the rod shrinking and drawing, the method further comprises: drying the immersed reaction tube. 9. The method for preparing the E and S band extended bismuth-doped optical fiber according to claim 6, characterized in that in the prepared optical fiber, the concentration range of _Bi2O3 is _100-2000ppm ; when the core is doped with _phosphorus , the concentration range of _P2O5 is 100-15000ppm; when the core is doped with germanium, the concentration range of _GeO2 is 500-10000ppm. 10. The method for preparing the E and S band extended bismuth-doped optical fiber according to claim 6, characterized in that the diameter of the core of the prepared optical fiber is 4 to 10 μm, and the diameter of the cladding is 120±5 μm.