CN209981720U - Double-arm structure annular light spot output continuous optical fiber laser - Google Patents

Abstract

The utility model discloses a double-arm structure annular facula output continuous fiber laser, the laser comprises two arms, each arm is formed by connecting a coupler, a pumping source, a wavelength division multiplexer, a gain fiber and a mode conversion device in sequence, a polarization beam splitter connecting the two arms is connected with an output end, the fiber used by the laser is a polarization maintaining fiber, so as to maintain the mutually orthogonal LP11 mode in the two arms, and the output is combined by the polarization beam splitter; the problem of present LP11 mode full fiber laser annular facula output unstable, inhomogeneous is solved, the practicality of the fiber laser of high order mode beam output has been promoted, can be widely applied to fields such as industry laser processing, surface plasma arouses, particle manipulation, microimaging and optical storage.

Description

Double-arm structure annular light spot output continuous optical fiber laser

Technical Field

The utility model relates to a fiber laser technical field specifically is a continuous fiber laser of both arms structure annular facula output.

Background

The cylindrical vector beam is an axisymmetric polarized beam, the modes of the cylindrical vector beam are 4 degenerate vector modes in an LP11 mode in an optical fiber, and the difference of the axisymmetric polarized beam relative to the traditional uniformly polarized beam is that the polarization direction of the axisymmetric polarized beam presents non-uniform cylindrical symmetric distribution on a cross section perpendicular to the propagation direction, the optical field distribution presents a hollow annular distribution, but due to errors in the manufacturing process of the optical fiber and crosstalk of modes in the optical fiber, the output light spot of an actual high-order mode optical fiber laser has the problem of unstable non-uniformity, and the annular light spot is obtained, so that an additional device is needed for relieving the degeneracy of an LP11 mode. In view of the special annular light field distribution and polarization characteristics of the cylindrical vector light, especially the angular polarized light and the radial polarized light have unique focusing characteristics, and the cylindrical vector light plays an important role in numerous fields. Under the condition of tight focusing, a focusing electric field of the radial polarized light beam is dominated by a longitudinal component with high intensity and small size, the size of a focal spot of the radial polarized light beam is far smaller than that of a focusing spot of linear polarized light under the same condition, and the radial polarized light beam can be regarded as a two-dimensional P polarized light beam when being focused, so that the radial polarized light beam has great application value in the aspects of exciting surface plasma, processing laser, manipulating particles and the like. The angular polarized light still has annular optical field distribution at a focus after being focused, so that the particle trap is suitable for trapping particles with refractive indexes smaller than that of the surrounding environment.

The current methods for generating the cylindrical vector beam mainly include an active mode and a passive mode. The active mode is mainly to generate a column vector beam by using the loss of some polarization states in the beam by using a birefringent crystal in a cavity or by using the superposition of the polarization states, and the method has the problems of high requirement on the precision of a device and relatively small action range; the passive mode is to add a polarization control device in or outside the laser cavity, which has the disadvantages of easy environmental interference, poor stability and low practicability.

SUMMERY OF THE UTILITY MODEL

The utility model aims at solving the shortcoming that current high order mode beam output fiber laser poor stability, output facula are inhomogeneous, the practicality is low, based on the interference immunity of polarization maintaining fiber to the environment, designed and made a continuous fiber laser of both arms structure annular facula output.

In order to achieve the above object, the utility model provides a following technical scheme: a double-arm structure annular light spot output continuous optical fiber laser comprises two arms, wherein each arm is formed by sequentially connecting a coupler, a pumping source, a wavelength division multiplexer, a gain optical fiber and a mode conversion device, a polarization beam splitter connecting the two arms is connected with an output end, a stable orthogonal polarization LP11 mode exists in the two arms by using a polarization maintaining optical fiber, and the two arms are combined by the polarization beam splitter to form a complete ring and output through the output end; the coupler is used as a total reflection mirror by connecting two output ports, a pump source is used for providing energy, a wavelength division multiplexer is used for coupling pump light into a laser cavity, a gain optical fiber is used for providing gain and generating and amplifying signal light, a mode conversion device is used for converting an LP01 mode in the optical fiber into an LP11 mode, a polarization-maintaining optical fiber is used for maintaining a signal light mode field in two arms to be a two-lobe structure with polarization and mutually orthogonal shape, a polarization beam splitter connected with the two arms is used for combining light beams in the two arms into a laser beam with a complete annular light spot, and an output end is used for outputting the laser and reflecting part of the laser to realize feedback.

Preferably, the gain fiber is a polarization maintaining fiber, and the doped rare earth element of the polarization maintaining fiber comprises at least one of ytterbium, erbium and thulium.

Preferably, the mode conversion device comprises at least one of a long period grating, a mode selective coupler and a miscut fusion cut on a polarization maintaining optical fiber.

Compared with the prior art, the beneficial effects of the utility model are that:

1. the utility model is of an all-fiber structure, and has compact and stable structure;

2. the laser in the two arms of the utility model is incoherent, and the output facula can be regulated and controlled by changing the parameters of the cavity length, the pumping and the like;

3. the utility model discloses a LP11 mode exists at the laser intracavity stability to output the even annular facula of rule.

Drawings

Fig. 1 is a schematic structural diagram of the dual-arm structure annular light spot output continuous fiber laser of the present invention.

In the figure: 1-a coupler; 2-a pump source; 3-wavelength division multiplexer; a 4-gain optical fiber; a 5-mode conversion device; 6-a polarizing beam splitter; 7-output end.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Referring to fig. 1, the present invention provides a technical solution: a double-arm structure annular light spot output continuous optical fiber laser comprises two arms, wherein each arm is formed by sequentially connecting a coupler 1, a pumping source 2, a wavelength division multiplexer 3, a gain optical fiber 4 and a mode conversion device 5, and a polarization beam splitter 6 for connecting the two arms is connected with an output end 7; in the laser, a coupler 1 is used as a total return mirror, a semiconductor laser with the central wavelength of 975nm is adopted as a pumping source 2, a 975nm/1064nm wavelength division multiplexer is adopted as a wavelength division multiplexer 3, a gain fiber 4 is an ytterbium-doped polarization maintaining fiber and can absorb pumping light to generate signal light, and a mode conversion device 5 is a long-period grating engraved on the polarization maintaining fiber; after passing through the mode conversion device 5, the signal light is converted into an LP11 mode by a fundamental mode LP01, under the stress birefringence effect of the polarization-maintaining optical fiber, mode field distribution of two lobes is formed and maintained, by adjusting the fast and slow axis directions of the two-arm optical fiber, the mode fields of the two arms are orthogonally input into the polarization beam splitter 6 and output a beam of signal light with a complete ring shape, after being partially reflected at the output end 7, the signal light passes through the polarization beam splitter 6 again and is split into two beams of light beams with mode field distribution of two lobes, the two beams enter the two corresponding arms respectively, and finally, the signal light continuously oscillates in the laser cavity to form continuous laser and is output through the output end 7.

The utility model has the advantages of utilize polarization maintaining fiber to the interference immunity of environment and polarization beam splitter 6's light path reversibility for the LP11 mode exists stably in the laser cavity, and has guaranteed the evenly distributed of output facula.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (3)

1. The utility model provides a continuous fiber laser of annular facula output of both arms structure which characterized in that, includes two arms, and every arm includes:

a coupler (1);

a pump source (2);

a wavelength division multiplexer (3);

gain fiber (4) and

a mode conversion device (5), said coupler (1) acting as a total reflection mirror;

wherein the pump source (2) is used for generating pump light;

wherein the wavelength division multiplexer (3) is used for coupling the pump light into the resonant cavity;

wherein the gain fiber (4) is used for absorbing the pump light and generating signal light;

wherein the mode conversion device (5) is configured to convert the LP01 mode into the LP11 mode;

the coupler (1), the pumping source (2), the wavelength division multiplexer (3), the gain fiber (4) and the mode conversion device (5) in the two arms are respectively connected in sequence, the mode conversion devices (5) in the two arms are simultaneously connected with the polarization beam splitter (6), and the polarization beam splitter (6) is connected with the output end (7);

the polarization beam splitter (6) is used for combining two beams of laser with orthogonal polarization states;

wherein the output end (7) is used for outputting the signal light and reflecting part of the signal light to realize feedback.

2. The two-arm structure annular spot output continuous fiber laser according to claim 1, characterized in that: the gain fiber (4) is a polarization maintaining fiber, and doped rare earth elements of the polarization maintaining fiber comprise at least one of ytterbium, erbium and thulium.

3. The two-arm structure annular spot output continuous fiber laser according to claim 1, characterized in that: the mode conversion device (5) comprises at least one of a long period grating, a mode selective coupler and a dislocation fusion splice, which are engraved on a polarization maintaining optical fiber.

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