CN210514690U - All-fiber filter based on hybrid fiber structure - Google Patents

Abstract

The technology relates to an all-fiber filter based on a hybrid fiber structure, which comprises a common single-mode fiber 10, a few-mode fiber 21, a first ellipsoidal fiber structure 31 formed by fusion welding of the common single-mode fiber 10 and the few-mode fiber 21, a second ellipsoidal fiber structure 32 formed by fusion welding of the few-mode fiber 21 and the few-mode fiber 21, and an eccentric fusion point 33 of the few-mode fiber 21 and the common single-mode fiber 10. The first ellipsoidal fiber structure 31 and the second ellipsoidal fiber structure 32 can increase the degree of mode field mismatch, so that a high-order mode can be excited more effectively, coupling occurs again at the core-shifting fusion point 33, and the two structures are utilized to obtain a higher filtering extinction ratio. The filter has the advantages of simple manufacturing method, compact structure, small volume and good stability. The fiber laser is used for a fiber laser system, and the integrity of the fiber laser can be ensured due to the full-fiber structure of the fiber laser, and the fiber laser with switchable output laser wavelength quantity and adjustable laser wavelength position can be obtained.

Description

All-fiber filter based on hybrid fiber structure

Technical Field

The technology relates to an all-fiber filter based on a hybrid fiber structure, and belongs to the field of fiber lasers and instruments and meters.

Background

Fiber lasers were invented in 1963 and through the first commercial fiber lasers appeared in the market at the end of the 80's 20 th century, they have undergone a development course of more than 20 years. A fiber laser is known as an amplifier for ultra high-speed optical communication. The fiber laser technology has wide application prospect and great scientific and technological advantages in the aspects of high-speed and high-capacity wavelength division multiplexing fiber communication systems, high-precision fiber sensing technology, high-power laser and the like. With the development of communication technology, communication services will be shifted to broadband services represented by high-speed IP data and multimedia, which puts higher and higher demands on the bandwidth and capacity of optical communication networks, and the mature application of Dense Wavelength Division Multiplexing (DWDM) technology greatly increases the capacity of optical fiber communication systems. With the increase of the number of optical channels in DWDM systems, various optical multi-wavelength filter technologies become hot research in the field of optical fiber communication.

In recent years, a multi-wavelength fiber laser has attracted much attention because of its potential wide application in the fields of fiber communication systems, fiber sensing, dense wavelength division multiplexing, optical device testing, microwave photonics, and the like. Researchers have also proposed many kinds of multi-wavelength fiber filters to develop multi-wavelength fiber lasers in response to this hot spot. Mainly includes Fabry-Perot resonant filter (Stone J, Stulz L W. fiber obtained high-fine tuned fiber resonator with large, medium and small free spectral filters [ J ]. Electron modulators, 1987,23(15):781 783), Mach-Zehnder interference filter (Ahn J T, Leeh K, Jeon M Y, et al. Continuou tunable multi-fiber resonator with stable fiber-optical modulator [ J ]. Optics, 165, 1999, (1) 33-37-magnetic ring interference filter (simulation, S. hybrid-optical fiber coupler [ J ]. 12. fiber resonator J. (IEEE-fiber resonator of fiber resonator type), IEEE-fiber coupler [ 12. fiber resonator J.: IEEE-coupler [ J ]. 12 ] and two-fiber resonator filters [ 12. E. fiber coupler [ J ]. 12. fiber coupler [ 12 ] and IEEE-fiber coupler [ 12. waveguide ] coupler [ 12. fiber resonator J ], 1998,23(16): 1277-. However, the multi-wavelength filters of these several schemes have some problems. The Fabry-Perot resonant filter needs to meet specific matching conditions when multiple wavelengths are realized, and the number of the wavelengths of the filter is not adjustable after the cavity length of the Fabry-Perot resonant cavity is determined. In the manufacturing process of the Mach-Zehnder interference filter, the Mach-Zehnder interference filter is sensitive to temperature and vibration of the external environment, and the difference between the two arm lengths of the Mach-Zehnder interference filter cannot be too large, so that the Mach-Zehnder interference filter cannot be used commercially. The Sagnac loop interference filter requires writing fiber gratings on the loop or inserting high birefringence fibers, and the number of wavelengths is not adjustable after the Sagnac loop interference filter is successfully manufactured. The manufacturing process of the double-core optical fiber type filter is complex, and the extinction ratio of the filter is low. After a plurality of grating filters are applied to a laser, the number of output laser wavelengths is generally equal to the number of gratings used in the laser, and the increase of the number of gratings increases the insertion loss and the structural complexity. Therefore, the technology provides an all-fiber filter with a novel hybrid fiber structure, the manufacturing method is simple, and the requirement on manufacturing process equipment is low; the structure is compact, the volume is small, and the cost of later packaging and integration of the multi-wavelength fiber laser is greatly reduced; the filtering extinction ratio is high, and laser output with high optical signal-to-noise ratio is obtained; the stability is good, and the stability of the output wavelength of the multi-wavelength laser and the smaller fluctuation of the output laser power are ensured; the all-fiber structure ensures the integrity and the uniformity of the fiber laser and avoids the insertion loss caused by external modulation.

Disclosure of Invention

In order to realize switchable multi-wavelength fiber laser, the technology provides a novel all-fiber filter with a hybrid fiber structure, the filter is mainly based on a mode field mismatch principle, a double-ellipsoid fiber structure is manufactured in the filter structure by welding through an optical fiber welding machine, the mode field mismatch degree is increased, more high-order modes are excited, core-shifting welding is adopted at the other end of the filter, and the extinction ratio of the filter is deepened. The optical fiber filter has the advantages that after the optical fiber filter is applied to an optical fiber laser, multi-wavelength laser output can be obtained, the number state of output lasers can be switched, and the position of the output lasers can be adjusted.

The technical purpose is realized by the following technical scheme:

the utility model provides a novel mixed fiber structure all-fiber filter, this filter includes ordinary single mode fiber, few mode fiber, ordinary single mode fiber and the first ellipsoid fiber structure that few mode fiber butt fusion formed, the second ellipsoid fiber structure that few mode fiber and few mode fiber butt fusion formed, few mode fiber and ordinary single mode fiber's eccentric core splice point constitutes an all-fiber filter through fiber coupling's mode between each structure. The common single-mode optical fiber is connected with the few-mode optical fiber, the middle of the common single-mode optical fiber is provided with a first ellipsoid optical fiber structure formed by fusion welding of the common single-mode optical fiber and the few-mode optical fiber and a second ellipsoid optical fiber structure formed by fusion welding of the few-mode optical fiber and the few-mode optical fiber, and then the few-mode optical fiber and the common single-mode optical fiber are subjected to staggered core fusion welding to form a core deviation fusion point.

Preferably, the single mode fiber may be a common single mode fiber or a thin core single mode fiber, wherein a core diameter of the thin core single mode fiber may be 4-6 μm, and a cladding diameter is 125 μm.

Preferably, the core diameter of the few-mode optical fiber can be 8-10 μm, and the cladding diameter is 125 μm.

Preferably, the maximum cladding diameter of the first ellipsoidal fiber structure and the second ellipsoidal fiber structure can be 160-260 μm, and the fusion distance between the two structures is 3-20 mm.

Preferably, the first ellipsoidal optical fiber structure, the second ellipsoidal optical fiber structure and the core shift welding point are manufactured by an optical fiber welding machine.

Preferably, the core shift welding points adopt core shift welding, and the core shift welding degree is 0-10 μm.

The beneficial effects of the technology are as follows: novel mixed optical fiber structure all-fiber filter, because the mode excitation is carried out to the two ellipsoid optical fiber structure that it adopted, the mode is interfered in addition to eccentric core butt fusion mode for this optical fiber filter possesses high filtering extinction ratio, uses fiber laser with it, can obtain multi-wavelength laser output, and the changeable and output laser position of output laser quantity state simultaneously is adjustable. The filter is simple in manufacturing method and low in requirements on manufacturing process equipment; the structure is compact, the volume is small, and the cost of later packaging and integration of the multi-wavelength fiber laser is greatly reduced; the stability is good, and the stability of the output wavelength of the multi-wavelength laser and the smaller fluctuation of the output laser power are ensured; the all-fiber structure ensures the integrity and the uniformity of the fiber laser and avoids the insertion loss caused by external modulation.

Drawings

Fig. 1 is a schematic structural diagram of an optical fiber filter with a double-ellipsoid structure and core-shift fusion connection manufactured by a common single-mode optical fiber and a few-mode optical fiber.

Fig. 2 is a schematic structural diagram of a fiber filter with a double-ellipsoid structure and core-shift fusion made of a thin-core single-mode fiber and a few-mode fiber.

Fig. 3 is a schematic structural view of a fiber filter with a dual-ellipsoid structure formed by a thin-core single-mode fiber and a few-mode fiber and connected in a forward direction.

Detailed Description

The present technology is further described below with reference to the accompanying drawings.

Example one

In this embodiment, a new hybrid fiber structure fiber filter is made of a common single mode fiber 10 and a few-mode fiber 21, as shown in fig. 1. The filter includes: the optical fiber comprises a common single-mode optical fiber 10, a few-mode optical fiber 21, a first ellipsoidal optical fiber structure 31 formed by fusion welding the common single-mode optical fiber 10 and the few-mode optical fiber 21, a second ellipsoidal optical fiber structure 32 formed by fusion welding the few-mode optical fiber 21 and the few-mode optical fiber 21, and an eccentric fusion point 33 of the few-mode optical fiber 21 and the common single-mode optical fiber 10. Wherein the distance between the first ellipsoidal fiber structure 31 and the second ellipsoidal fiber structure 32 is 3mm, the core radius of the few-mode fiber 21 is 8 μm, and the cladding diameter is 125 μm; the diameter of a fiber core of the common single-mode optical fiber 10 is 9 mu m, and the diameter of a cladding is 125 mu m; the maximum cladding diameters of the first ellipsoidal fiber structure 31 and the second ellipsoidal fiber structure 32 are both 160 μm; the eccentric welding distance at the eccentric welding point 33 was 5 μm.

Example two

In this embodiment, a new hybrid fiber structure fiber filter is made of a thin-core single-mode fiber 11 and a few-mode fiber 22, as shown in fig. 2. The filter includes: the core-spun single-mode fiber comprises a thin-core single-mode fiber 11, a few-mode fiber 22, a first ellipsoidal fiber structure 34 formed by fusion welding of the thin-core single-mode fiber 11 and the few-mode fiber 22, a second ellipsoidal fiber structure 35 formed by fusion welding of the few-mode fiber 22 and the few-mode fiber 22, and an off-core fusion welding point 36 of the few-mode fiber 22 and the thin-core single-mode fiber 11. Wherein, the distance between the first ellipsoidal fiber structure 34 and the second ellipsoidal fiber structure 35 is 10mm, the core radius of the few-mode fiber 22 is 9 μm, and the cladding diameter is 125 μm; the core diameter of the thin-core single-mode fiber 11 is 6 μm, and the cladding diameter is 125 μm; the maximum cladding diameters of the first ellipsoidal fiber structure 34 and the second ellipsoidal fiber structure 35 are both 220 μm; the eccentric welding distance at the eccentric welding point 36 was 10 μm.

EXAMPLE III

In this example, a new hybrid fiber structure fiber filter is made of a thin-core single-mode fiber 12 and a few-mode fiber 23, as shown in fig. 3. The filter includes: the core-spun single-mode fiber comprises a thin-core single-mode fiber 12, a few-mode fiber 23, a first ellipsoidal fiber structure 37 formed by fusion welding of the thin-core single-mode fiber 12 and the few-mode fiber 23, a second ellipsoidal fiber structure 38 formed by fusion welding of the few-mode fiber 23 and the few-mode fiber 23, and an eccentric fusion welding point 39 of the few-mode fiber 23 and the thin-core single-mode fiber 12. Wherein, the distance between the first ellipsoidal fiber structure 37 and the second ellipsoidal fiber structure 38 is 20mm, the core radius of the few-mode fiber 23 is 10 μm, and the cladding diameter is 125 μm; the core diameter of the thin-core single-mode fiber 12 is 4 μm, and the cladding diameter is 125 μm; the maximum cladding diameters of the first and second ellipsoidal fiber structures 37 and 38 are both 260 μm; the eccentric welding distance at the eccentric welding point 39 is 0 μm.

Claims (6)

1. The utility model provides an all-fiber filter based on hybrid fiber structure which characterized in that: the optical fiber comprises a common single-mode fiber (10), a few-mode fiber (21), a first ellipsoidal fiber structure (31) formed by fusion of the common single-mode fiber (10) and the few-mode fiber (21), a second ellipsoidal fiber structure (32) formed by fusion of the few-mode fiber (21) and the few-mode fiber (21), core-shifting fusion points (33) of the few-mode fiber (21) and the common single-mode fiber (10), an all-fiber filter formed by fiber coupling among the structures, wherein the common single-mode fiber (10) is connected with the few-mode fiber (21), the middle part comprises a first ellipsoidal fiber structure (31) formed by welding a common single-mode fiber (10) and a few-mode fiber (21) and a second ellipsoidal fiber structure (32) formed by welding the few-mode fiber (21) and the few-mode fiber (21), then, the few-mode optical fiber (21) is connected with the common single-mode optical fiber (10) to form an eccentric fusion point (33).

2. The all-fiber filter based on the hybrid fiber structure as claimed in claim 1, wherein: the single-mode fiber can be a common single-mode fiber (10) or a thin-core single-mode fiber (11), wherein the core diameter of the thin-core single-mode fiber (11) can be 4-6 mu m, and the cladding diameter is 125 mu m.

3. The all-fiber filter based on the hybrid fiber structure as claimed in claim 1, wherein: the core diameter of the few-mode optical fiber (21) can be 8-10 mu m, and the cladding diameter is 125 mu m.

4. The all-fiber filter based on the hybrid fiber structure as claimed in claim 1, wherein: the maximum cladding diameter of the first ellipsoidal fiber structure (31) and the second ellipsoidal fiber structure (32) can be 160-260 μm, and the fusion distance between the two structures is 3-20 mm.

5. The all-fiber filter based on the hybrid fiber structure as claimed in claim 1, wherein: the first ellipsoidal optical fiber structure (31), the second ellipsoidal optical fiber structure (32) and the core shift fusion point (33) are manufactured by an optical fiber fusion splicer.

6. The all-fiber filter based on the hybrid fiber structure as claimed in claim 1, wherein: the core shift welding points (33) adopt core shift welding, and the core shift welding degree can be 0-10 mu m.

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