Manufacturing technique of ultra-wideband high gain optical fibers and devices

Abstract

A manufacturing technique of ultra-wideband high gain optical fibers and devices is disclosed, including: (1) manufacturing a gain fiber, which is a composite structural optical fiber, having a core composed of a plurality of sets of sector structures distributed symmetrically or a plurality of concentric ring structures. The core is composed of at least two kinds of rare-earth-ion-doped glass, and luminescence centers are located in different sector or ring structure regions; and (2) constructing a fiber laser: using the gain fiber, selectively exciting rare earth ions in different regions in the core by controlling a shape of pump light spot, and combining with fiber grating pairs to realize a tunable laser output. The present disclosure can manufacture gain fibers with high-gain and ultra-wideband characteristics by combining the design of the fiber structure and the control of the light field of the pump light.

Claims

1. A manufacturing technique of ultra-wideband high gain optical fibers and devices, comprising following steps: (1) manufacturing a gain fiber, wherein the gain fiber is a composite structural optical fiber comprising a core and a cladding, the core is composed of a plurality of sets of symmetrically distributed sector structures or a plurality of concentric ring structures, the plurality of sets of sector structures or the plurality of ring structures are composed of at least two kinds of rare-earth-ion-doped glass, luminescence centers of rare earth ions are located in different sector structure regions or ring structure regions in the core respectively, and the gain fiber has a gain coefficient larger than 1 dB/cm, and a gain bandwidth greater than 150 nm; and (2) constructing a fiber laser, comprising: using the composite structural optical fiber in step (1) as the gain fiber, selectively exciting the rare earth ions in different sector structure regions or ring structure regions in the core by controlling a shape of a pump light spot, and combining with fiber grating pairs to achieve tunable laser output; wherein the shape of the pump light spot is controlled by a mode selective coupler and/or a fiber polarization controller in step (2): wherein: for the gain fiber of which the core is composed of the ring structures, pump light is converted into a vector mode by the mode selective coupler, to generate ring pump light, and temperature or stress regulation is performed on the mode selective coupler to convert the pump light into the vector mode in a different order, so that the maximum values of light field are located in the ring structure regions doped with different rare earth ions, thereby exciting different rare earth luminescence centers to generate corresponding gains, and realizing laser switching between different wavebands; and central operating wavelengths of fiber rating pairs at both ends of the gain fiber are adjusted by a temperature or stress regulating device to implement that a wavelength of output laser is tunable in a specific waveband; for the gain fiber of which the core is composed of the sector structures, pump light is converted into a linear polarization mode with a two-lobed spot shape by the mode selective coupler, and an LP.sub.11 mode is controlled to rotate by the polarization controller, so that the maximum values of light field are located in the sector structure regions doped with different rare earth ions, thereby exciting different rare earth luminescence centers to generate corresponding gains, and realizing laser switching between different wavebands; and central operating wavelengths of fiber grating pairs at both ends of the gain fiber are adjusted by a temperature or stress regulating device to implement that a wavelength of output laser is tunable in a specific waveband.

2. The manufacturing technique of ultra-wideband high gain optical fibers and devices according to claim 1, wherein a method of manufacturing the gain fiber in step (1) is a rod-in-tube method, a molten core drawing method, a high pressure assisted melt filling method, a high pressure chemical vapor deposition method, a double crucible method, a casting method, an extrusion molding method or a 3D printing method.

3. The manufacturing technique of ultra-wideband high gain optical fibers and devices according to claim 1, wherein the rare-earth-ion-doped glass is multi-component glass.

4. The manufacturing technique of ultra-wideband high gain optical fibers and devices according to claim 3, wherein the multi-component glass, is selected from one or more of multi-component germanate glass, multi-component phosphate glass, multi-component tellurite glass, multi-component chalcogenide glass, multi-component fluoride glass, multi-component aluminate glass, multi-component borate glass, multi-component silicate glass, multiple-component bismuthate glass, multi-component germanosilicate glass.

5. The manufacturing technique of ultra-wideband high gain optical fibers and devices according to claim 4, wherein the multi-component glass is one or more of multi-component germanate glass, multi-component silicate glass or multi-component tellurite glass.

6. The manufacturing technique of ultra-wideband high gain optical fibers and devices according to claim 1, wherein the cladding is composed of multi-component glass.

7. The manufacturing technique of ultra-wideband high gain optical fibers and devices according to claim 6, wherein the multi-component glass is selected from one or more of multi-component germanate glass, multi-component phosphate glass, multi-component tellurite glass, multi-component chalcogenide glass, multi-component fluoride glass, multi-component aluminate glass, multi-component borate glass, multi-component silicate glass, multiple-component bismuthate glass, multi-component germanosilicate glass.

8. The manufacturing technique of ultra-wideband high gain optical fibers and devices according to claim 7, wherein the multi-component glass is one or more of multi-component germanate glass, multi-component silicate glass or multi-component tellurite glass.

9. The manufacturing technique of ultra-wideband high gain optical fibers and devices according to claim 1, wherein the cladding has a single cladding structure or a multi-cladding structure.

10. The manufacturing technique of ultra-wideband high gain optical fibers and devices according to claim 9, wherein an outer surface of the cladding further comprises a coating layer.

11. The manufacturing technique of ultra-wideband high gain optical fibers and devices according to claim 1, wherein the composite structural optical fiber is a single mode optical fiber.

12. The manufacturing technique of ultra-wideband high gain optical fibers and devices according to claim 1, wherein the rare earth ions are selected from one or more kinds of Er.sup.3+, Tm.sup.3+, Ho.sup.3+, Ce.sup.3+, Eu.sup.3+, Eu.sup.2+, Sm.sup.3+, Sm.sup.2+, Tb.sup.3+, Nd.sup.3+, Dy.sup.3+, Yb.sup.3+ or Pr.sup.3+.

13. The manufacturing technique of ultra-wideband high gain optical fibers and devices according to claim 1, wherein the composite structural optical fiber is a single mode optical fiber, the core is in a configuration of concentric ring structures, and a number of the ring structures is 2-3.

14. The manufacturing technique of ultra-wideband high gain optical fibers and devices according to claim 3, wherein the composite structural optical fiber is a single mode optical fiber, the core is in a configuration of sets of symmetrically distributed sector structures, and a number of the sets of symmetrically distributed sector structures is 2-3.

15. The manufacturing technique of ultra-wideband high gain optical fibers and devices according to claim 1, wherein each of the core and the cladding is composed of multi-component germanate glass, and the rare earth ions are selected from two or three of Er.sup.3+/Yb.sup.3+, Tm.sup.3+/Yb.sup.3+, or Ho.sup.3+/Yb.sup.3+.

16. The manufacturing technique of ultra-wideband high gain optical fibers and devices according to claim 15, wherein each of the rare earth ions Er.sup.3+, Tm.sup.3+, Ho.sup.3+, and Yb.sup.3+ in the core has a doping concentration larger than 5 wt %, the gain fiber has a maximum gain coefficient larger than or equal to 5.2 dB/cm in a near-infrared waveband, and the gain fiber has a maximum gain coefficient larger than or equal to 3.2 dB/cm in a mid-infrared waveband.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a schematic diagram of cross-section of a gain fiber described in Embodiment 1;

(2) FIG. 2 illustrates a schematic diagram of a structure and laser output of a fiber laser described in Embodiment 1;

(3) FIG. 3 illustrates a schematic diagram of cross-section of a gain fiber described in Embodiment 2:

(4) FIG. 4 illustrates a schematic diagram of cross-section of a gain fiber described in Embodiment 3:

(5) FIG. 5 illustrates a schematic diagram of cross-section of a gain fiber described in Embodiment 4; and

(6) FIG. 6 illustrates a schematic diagram of a structure and laser output of a fiber laser described in Embodiment 4.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(7) A manufacturing technique of ultra-wideband high gain optical fibers and devices in the present disclosure will be further described in detail below in conjunction with specific embodiments.

Embodiment 1

(8) In this embodiment, a manufacturing technique of ultra-wideband high gain optical fibers and devices includes following steps.

(9) (1) Manufacturing a Gain Fiber

(10) A cross-section of the gain fiber is shown in FIG. 1. The gain fiber is a composite structural optical fiber including a core and a cladding 103 coating on a surface of the core. The core is composed of a rare-earth-ion-doped region 101 and a rare-earth-ion-doped region 102, which are arranged concentrically. The rare-earth-ion-doped region 101 is Er.sup.3+/Yb.sup.3+ co-doped multi-component silicate glass, the rare-earth-ion-doped region 102 is Tm.sup.3+/Yb.sup.3+ co-doped multi-component germanate glass, and the cladding 103 is multi-component germanate glass without rare earth ions. Each of Er.sup.3+, Tm.sup.3+, and Yb.sup.3+ has a doping concentration larger than 5 wt %.

(11) The gain fiber is manufactured by a molten core drawing method including the following steps.

(12) a. Glass melting: a conventional melting-annealing method is used to prepare bulk core glass, respectively, doped with Er.sup.3+/Yb.sup.3+ and Tm.sup.3+/Yb.sup.3+, and bulk cladding glass.

(13) b. Cladding glass processing: the prepared cladding glass is mechanically processed into a glass tube of a design size, and then the inner and outer surfaces are polished by physical and chemical methods to obtain the cladding 103.

(14) c. Manufacture of composite structural core rod: the composite structural core is manufactured by the molten core drawing method. The bulk Er.sup.3+/Yb.sup.3+ co-doped core glass is mechanically processed into a glass cylinder of a preset size, and the bulk Tm.sup.3+/Yb.sup.3+ co-doped core glass is mechanically processed into a glass tube of a preset size. Then the surfaces are polished by physical and/or chemical methods, and the processed core glass cylinder and the processed core glass tube are assembled into a composite structural core preform, that is, the rare-earth-ion-doped region 101 and the rare-earth-ion-doped region 102 are sequentially formed. A composite structural core rod of the preset size is obtained by drawing in a drawing tower. The sizes of the cladding and each core in steps b and c are determined according to the design requirements of a single mode optical fiber.

(15) d. Optical fiber drawing: the composite structural core rod and the cladding glass tube are assembled into a composite structural fiber preform, which is drawn into the gain fibers by a molten core drawing method, and the cross-section of the gain fiber is shown in FIG. 1.

(16) As measured by a small signal gain test method, the composite structural optical fiber has a maximum gain coefficient of 5.7 dB/cm in the near-infrared waveband, and a maximum gain coefficient of 3.2 dB/cm in the mid-infrared waveband.

(17) (2) Constructing a Fiber Laser

(18) A tunable laser output is realized by constructing a fiber laser using the above-described gain fiber. The structure of the fiber laser and the laser output are shown in FIG. 2. The 980 nm pump light is converted into a vector mode by a mode selective coupler, to generate ring pump light. Temperature or stress control is performed on the mode selective coupler to convert the pump light into vector modes of different orders (HE.sub.11 and HE.sub.91), so that a maximum value of light field is located in the rare-earth-ion-doped region 101 or the rare-earth-ion-doped region 102, thereby exciting different rare earth ions to generate corresponding gains, and realizing laser switching between different wavebands. Central operating wavelengths of fiber grating pairs at both ends of the composite structural gain fiber can be adjusted by a temperature or stress regulating device, and the lasing wavelength is tunable in a specific waveband from 1,450 nm to 2,050 nm.

Embodiment 2

(19) In this embodiment, a manufacturing technique of ultra-wideband high gain optical fibers and devices includes the following steps.

(20) (1) Manufacturing a Gain Fiber

(21) A cross-section view of the gain fiber is shown in FIG. 3. The gain fiber includes a core and a cladding 304 coating on the surface of the core. The core is composed of a rare-earth-ion-doped region 301, a rare-earth-ion-doped region 302, and a rare-earth-ion-doped region 303, which are arranged concentrically. The rare-earth-ion-doped region 301 is Er.sup.3+/Yb.sup.3+ co-doped multi-component germanate glass, the rare-earth-ion-doped region 302 is Tm.sup.3+/Yb.sup.3+ co-doped multi-component germanate glass, the rare-earth-ion-doped region 303 is Ho.sup.3+/Yb.sup.3+ co-doped multi-component germanate glass, and the cladding 304 is multi-component germanate glass without rare earth ions. Each of Er.sup.3+, Tm.sup.3+, Ho.sup.3+ and Yb.sup.3+ has a doping concentration larger than 5 wt %.

(22) The gain optical fiber is manufactured by a rod-in-tube method including the following steps.

(23) a. Glass melting: a conventional melting-annealing method is used to prepare bulk core glass, respectively, doped with Er.sup.3+/Yb.sup.3+, Tm.sup.3+/Yb.sup.3+, and Ho.sup.3+/Yb.sup.3+, and bulk cladding glass.

(24) b. Cladding glass processing: the melted cladding glass is mechanically processed into a glass tube of a design size, and then the inner and outer surfaces are polished by physical and chemical methods to obtain the cladding 304.

(25) c. Manufacture of composite structural core rod: the composite structural core is manufactured by the rod-in-tube method, the bulk Er.sup.3+/Yb.sup.3+ co-doped core glass is mechanically processed into a glass cylinder of a preset size, and the bulk Tm.sup.3+/Yb.sup.3+ and Ho.sup.3+/Yb.sup.3+ co-doped core glasses are mechanically processed into glass tubes of preset sizes, respectively. Then the surfaces are polished by physical and/or chemical methods and the processed core glass cylinder and the processed core glass tubes are assembled into a composite structural core preform, that is, the rare-earth-ion-doped region 301, the rare-earth-ion-doped region 302, and the rare-earth-ion-doped region 303 are sequentially formed. A composite structural core rod of the preset size is obtained by drawing the preform in a drawing tower. The sizes of the cladding and each core in steps b and c are determined according to the design requirements of a single mode optical fiber.

(26) d. Optical fiber drawing: the composite structural core rod and the cladding glass tubes are assembled into a composite structural fiber preform, which is drawn into the gain fibers, and their cross-section is shown in FIG. 3.

(27) As measured by a small signal gain test method, the composite structural optical fiber has a maximum gain coefficient of 6.5 dB/cm in the near-infrared waveband, and a maximum gain coefficient of 5.5 dB/cm in the mid-infrared waveband.

(28) (2) Constructing a Fiber Laser

(29) A tunable laser output is realized by constructing a fiber laser using the above-described gain fiber. The 980 nm pump light is converted into a vector mode by a mode selective coupler, to generate ring pump light. Temperature or stress control is performed on the mode selective coupler to convert the pump light into vector modes in different orders (HE.sub.11 and HE.sub.91), so that the maximum value of light field is located in the rare-earth-ion-doped region 301, the rare-earth-ion-doped region 302 or the rare-earth-ion-doped region 303, thereby exciting different rare earth ions to generate corresponding gains, and realizing laser switching between different wavebands. Central operating wavelengths of fiber grating pairs at both ends of the composite structural gain fiber can be adjusted by a temperature or stress regulating device, and the lasing wavelength is tunable in a specific waveband from 1,450 nm to 2,150 nm.

Embodiment 3

(30) In this embodiment, a manufacturing technique of ultra-wideband high gain optical fibers and devices includes following steps.

(31) (1) Manufacturing a Gain Fiber

(32) A cross-sectional view of the gain fiber is shown in FIG. 4. The gain fiber includes a core and a cladding 403 coating on the surface of the core. The core is composed of a rare-earth-ion-doped region 401 including a pair of sector structures arranged symmetrically and a rare-earth-ion-doped region 402 including a pair of sector structures arranged symmetrically. The rare-earth-ion-doped region 401 is Er.sup.3+/Yb.sup.3+ co-doped multi-component tellurite glass, the rare-earth-ion-doped region 402 is Tm.sup.3+/Yb.sup.3+ co-doped multi-component tellurite glass, and the cladding 403 is multi-component tellurite glass without rare earth ions. Each of Er.sup.3+, Tm.sup.3+ and Yb.sup.3+ has a doping concentration larger than 5 wt.

(33) The gain fiber is manufactured by the rod-in-tube method including the following steps.

(34) a. Glass melting: a conventional melting-annealing method is used to prepare bulk core glass, respectively, doped with Er.sup.3+/Yb.sup.3+ and Tm.sup.3+/Yb.sup.3+, and bulk cladding glass.

(35) b. Cladding glass processing: the melted cladding glass is mechanically processed into a glass tube of a design size, and then the inner and outer surfaces are polished by physical and chemical methods to obtain the cladding 403.

(36) c. Manufacture of composite structural core rod: the composite structural core is manufactured by a one-step drawing method and mechanical or laser cutting, the bulk Er.sup.3+/Yb.sup.3+ and Tm.sup.3+/Yb.sup.3+ co-doped core glasses are mechanically processed into glass cylinders of a preset size, respectively. And then the glass cylinders are drawn in a drawing tower to obtain core rods of a preset size after polishing the surfaces of the glass cylinders. The obtained core rods of a small size are respectively mechanically cut or cut by laser into four equal sectors which are then assembled into a composite structural core rod according to a design to form the rare-earth-ion-doped region 401 and the rare-earth-ion-doped region 402.

(37) d. Optical fiber drawing: the composite structural core rod and the cladding glass tubes are assembled into a composite structural fiber preform, which is drawn into the gain fibers. The cross-section of the gain fiber is shown in FIG. 4.

(38) As measured by a small signal gain test method, the composite structural optical fiber has a maximum gain coefficient of 6.2 dB/cm in the near-infrared waveband, and a maximum gain coefficient of 4.5 dB/cm in the mid-infrared waveband.

(39) (2) Constructing a Fiber Laser:

(40) A tunable laser output is realized by constructing a fiber laser using the above-described gain fiber. The 980 nm pump light is converted into a linear polarization mode LP.sub.11 with a two-lobed light spot shape, i.e., a light field has two maximum values in the azimuthal direction, by a mode selective coupler. The LP.sub.11 mode can be rotated by using a polarization controller, so that the maximum values of the light field are located in the rare-earth-ion-doped regions 401 or the rare-earth-ion-doped regions 402, thereby exciting different rare earth ions to generate corresponding gains, and realizing laser switching between different wavebands. Central operating wavelengths of the fiber grating pairs at both ends of the composite structural gain fiber can be adjusted by a temperature or stress regulating device, and the lasing wavelength is tunable in a specific waveband from 1,450 nm to 2,050 nm.

Embodiment 4

(41) In this embodiment, a manufacturing technique of ultra-wideband high gain optical fibers and devices includes following steps.

(42) (1) Manufacturing a Gain Fiber

(43) A cross-sectional view of the gain fiber is shown in FIG. 5. The gain fiber includes a core and a cladding 504 coating on the surface of the core. The core is composed of a rare-earth-ion-doped region 501 including a pair of sector structures arranged symmetrically, a rare-earth-ion-doped region 502 including a pair of sector structures arranged symmetrically, and a rare-earth-ion-doped region 503 including a pair of sector structures arranged symmetrically. The rare-earth-ion-doped region 501 is Er.sup.3+/Yb.sup.3+ co-doped multi-component germanosilicate glass, the rare-earth-ion-doped region 502 is Tm.sup.3+/Yb.sup.3+ co-doped multi-component germanosilicate glass, the rare-earth-ion-doped region 503 is Ho.sup.3+/Yb.sup.3+ co-doped multi-component germanosilicate glass, and the cladding 504 is multi-component germanate glass without rare earth ions. Each of Er.sup.3+, Tm.sup.3+, Ho.sup.3+ and Yb.sup.3+ has a doping concentration larger than 5 wt %.

(44) The gain fiber is manufactured by a three-dimensional printing method including the following steps.

(45) a. Manufacture of composite structural core rod: the cores with the sector structures are respectively manufactured by a three-dimensional printing process according to a design formula and size, and the cores are assembled into a composite structural core rod according to the design to form the rare-earth-ion-doped region 501, the rare-earth-ion-doped region 502, and the rare-earth-ion-doped region 503. And a cladding glass tube 504 is also manufactured by a three-dimensional printing process.

(46) d. Optical fiber drawing: the composite structural core rod and the cladding glass tube are assembled into a composite structural fiber preform, which is drawn into the gain fibers. The cross-section of the gain fiber is shown in FIG. 5.

(47) As measured by a small signal gain test method, the composite structural optical fiber has a maximum gain coefficient of 5.2 dB/cm in the near-infrared waveband, and a maximum gain coefficient of 3.2 dB/cm in the mid-infrared waveband.

(48) (2) Constructing a Fiber Laser

(49) A tunable laser output is realized by constructing a fiber laser using the above-described gain fiber. The schematic view of the structure and the laser output of the fiber laser are illustrated in FIG. 6. The 980 nm pump light is converted into a linear polarization mode LP.sub.11 with a two-lobed light spot shape, i.e., the light field has two maximum values in the azimuthal direction, by a mode selective coupler. The LP.sub.11 mode can be rotated by using a polarization controller, so that the maximum values of the light field are located in the rare-earth-ion-doped regions 501, the rare-earth-ion-doped regions 502, or the rare-earth-ion-doped regions 503, thereby exciting different rare earth ions to generate corresponding gains, and realizing laser switching between different wavebands. Central operating wavelengths of fiber grating pairs at both ends of the composite structural gain fiber can be adjusted by a temperature or stress regulating device, and the lasing wavelength is tunable in a specific waveband from 1,450 nm to 2,150 nm.

(50) It can be seen from Embodiments 1-4 that by combining the design of the optical fiber structure and the control of the light field of the pump light, a plurality of rare earth ions with different emission wavelengths can be independently integrated in the same optical fiber. By selectively exciting the luminescent ions in different regions of the core, while suppressing the fluorescence emission in other wavebands, and reducing the heat generation, a tunable laser output can be achieved more effectively, which is expected to be applied in the fields such as tunable wideband single frequency fiber lasers with high power, high efficiency, low noise and narrow line width, and tunable wideband ultra-high-repetition-rate mode-locked fiber lasers. Particularly in the infrared wideband, the tunable laser output has a significant effect. Two or three of the rare earth ions of Er.sup.3+/Yb.sup.3+, Tm.sup.3+/Yb.sup.3+, Ho.sup.3+/Yb.sup.3+ can be doped into the core, and Yb.sup.3+, is co-doped as sensitizer in each different region, thus the high-efficiency 1,450-2,050 nm or 1,450-2,150 m wideband illumination can be achieved by using a single-wavelength commercial pump source.

(51) The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction between the combinations of these technical features, all combinations should be considered within the scope of the description.

(52) The above-described embodiments merely represent several embodiments of the present disclosure, and the description thereof is more specific and detailed, but it is not to be construed as limiting the scope of the present disclosure. It should be noted that a number of deformations and improvements may be made by those skilled in the art without departing from the concept of the present disclosure. Therefore, the scope of the present disclosure should be determined by the appended claims.