CN214310974U - All-fiber mode conversion device - Google Patents

Abstract

The utility model provides a LP₀₁mode-LP₁₁All-fiber mode converter, base-mode signal (LP) embodying mode division multiplexing techniques₀₁) To higher order mode (LP)₁₁) Conversion, belonging to the field of optical communication. The whole device comprises: the fiber core comprises a fiber core cladding, a single-mode fiber core, a multi-mode fiber core and a few-mode fiber core. By injecting fundamental mode signals (LP) from the core of a single mode fibre₀₁) Exciting and outputting higher-order modes (LP) through multimode fiber₁₁). The utility model discloses be applied to optical communication mode multiplexing technique, can realize basic mode (LP)₀₁) To higher order mode (LP)₁₁) The conversion of (1); high order modes (LP) can also be implemented₁₁) Towards the fundamental mode signal (LP)₀₁) And (4) converting. The utility model discloses a youThe point is that the structure is simple, and the coupling efficiency can be effectively improved.

Description

All-fiber mode conversion device

Technical Field

The utility model relates to a LP₀₁mode-LP₁₁The mode all-fiber mode conversion device can realize the slave mode (LP) at 1550 nm wavelength by adjusting the parameter value of the structure₀₁) To higher order mode (LP)₁₁) Belonging to the technical field of optical fiber mode division multiplexing communication.

Background

Because the inherent effect of the Single Mode Fiber (SMF) easily reaches the shannon limit, the development of modern communication is inhibited, space division multiplexing is generated at this moment, space division multiplexing of the few-mode fiber (FMF) is called as Mode Division Multiplexing (MDM), and the Mode Converter (MC) is a core device of the mode division multiplexing, and needs to convert a fundamental mode into a high-order mode for system transmission. The mode converter device is small, small in communication volume, convenient to manufacture, relatively cheap and the like.

The mode division multiplexing technology uses few-mode optical fibers as transmission media, and uses mode orthogonality to regard each transmission mode as an independent channel for transmission, thereby greatly increasing the transmission speed and capacity. When the mode division multiplexing communication technology is used, a basic mode signal of a transmitting end needs to be converted into a high-order mode, and a few-mode optical fiber is added to cut off the high-order mode to achieve a filtering effect, so that the coupling effect is better; similarly, the high-order mode carrying information at the receiving end needs to be converted into a fundamental mode signal, and then signal processing is performed.

Mode converters implementing the mode division multiplexing technique up to now mainly fall into three categories: a spatial optical element method, a waveguide method, and an all-fiber method. The spatial optical element method comprises a Spatial Light Modulator (SLM) method and a Phase Plate (PP) method, the waveguide method comprises a waveguide photon lantern method, a long-period waveguide grating method and a planar optical waveguide method, and the all-fiber method comprises a photon lantern method, a mode selection coupler method, a multi-mode interference method, a taper method and a long-period fiber grating conversion method. These studies suffer from the disadvantages of low insertion loss, low extinction ratio, oversized, and not easy to integrate.

The utility model relates to a LP₀₁mode-LP₁₁The mode all-fiber mode converter can be used for converting the optical fiber mode into the optical fiber mode through literature retrieval,the same public reports as the present invention are not found.

Disclosure of Invention

The utility model discloses to the shortcoming of current mode conversion technique, basic mode signal (LP)₀₁) Conversion to higher order mode (LP)₁₁). The novel mode converter provided by the utility model has the advantages of small size, simple structure and easy integration. Similarly, the mode converter has reversibility, and can realize high-order mode (LP) in the same working bandwidth₁₁) Towards fundamental mode (LP)₀₁) And (4) converting.

The utility model discloses a fibre core cladding (1), single mode fiber core (2), multimode fiber core (3), few mode fiber core (4), the central axis of single mode fiber core (2) and the central axis's of multimode fiber core (3) interval are D1, the central axis of few mode fiber core (4) and the central axis's of multimode fiber core (3) interval are D2, multimode fiber core (3) are unanimous with the central axis of fibre core cladding (1), realize basic mode (LP)₀₁) Conversion to higher order mode (LP)₁₁) The mode converter of (1), wherein:

a. the fiber core cladding (1) uniformly covers the fiber core, the radius is R1, and the length is L;

b. the single-mode optical fiber core (2) has the radius R2 and the length L1;

c. the multimode fiber core (3) has the radius R3 and the length L2;

d. the small-mode optical fiber core (4) has the radius R4 and the length L3;

e. the central axes of the single-mode optical fiber core (2), the multimode optical fiber core (3) and the few-mode optical fiber core (4) are parallel, the distance between the central axes of the single-mode optical fiber core (2) and the multimode optical fiber core (3) is D1, and the distance between the central axes of the few-mode optical fiber core (4) and the multimode optical fiber core (3) is D2;

f. the refractive index n1 of the core cladding (1), the refractive indexes of the single-mode optical fiber core (2), the multimode optical fiber core (3) and the few-mode optical fiber core (4) are all n2, and n1 is less than n 2;

g. fundamental mode optical signal (LP)₀₁) The optical signal is input from a fundamental mode input port (P1) and is excited to convert a high-order mode (LP) through a multimode optical fiber core (3)₁₁) The optical signal with high-order mode passes through the few-mode optical fiber core (4) finallyAnd is output from the output port (P2).

h. Along with the transmission of signals, the effective refractive index of a fundamental mode in the single-mode optical fiber core (2) is gradually reduced, the effective refractive index of a high-order mode output by the multimode optical fiber core (3) is increased, and when the effective refractive index of a certain high-order mode is equal to the effective refractive index of the fundamental mode, phase matching is completed, so that mode conversion is realized.

i. The method is characterized in that the length L1 of the single-mode optical fiber core (2), the radius R2 of the fundamental mode input port (P1) of the single-mode optical fiber core (2), the length L2 of the multimode optical fiber core (3), the radius R3 of the multimode optical fiber core (3), the length L3 of the few-mode optical fiber core (4), the radius R4 of the output port (P2) of the few-mode optical fiber core (4), the distance between the central axes of the single-mode optical fiber core (2) and the multimode optical fiber core (3) is D1, the distance between the central axes of the few-mode optical fiber core (4) and the multimode optical fiber core (3) is D2 are adjusted, and the fundamental mode signal (LP) can be achieved₀₁) And converting to a higher order mode.

j. The optical waveguide structure is round or rectangular; LP where the higher-order modes of inversion are not critical when using rectangular waveguides₁₁Mode, is quasi LP₁₁Mode(s).

The utility model provides a LP₀₁mode-LP₁₁A mode all-fiber mode converter; the converter has reversibility, and can realize high-order mode (LP)₁₁) Towards the fundamental mode signal (LP)₀₁). The mode converter is insensitive to length, sensitive to fiber core refractive index, beneficial to integration, small in size and high in research value on future optical fiber mode division multiplexing systems.

The utility model provides a LP₀₁mode-LP₁₁A mode all-fiber mode converter; the converter has reversibility, and can realize high-order mode (LP)₁₁) Towards the fundamental mode signal (LP)₀₁). The mode converter is insensitive to length, sensitive to fiber core refractive index, beneficial to integration, small in size and high in research value on future optical fiber mode division multiplexing systems.

Drawings

FIG. 1 is LP₀₁mode-LP₁₁A structure diagram of a mode all-fiber mode converter.

FIG. 2 isLP₀₁mode-LP₁₁The modal all-fiber mode converter has a profile refractive index profile.

Detailed Description

In order to better describe the implementation process of the device of the present invention, the following description will be made with reference to the attached drawing 1 of the specification to explain the working process of the device

The all-fiber mode conversion device, comprising: the fiber core comprises a fiber core cladding (1), a single-mode fiber core (2), a multi-mode fiber core (3) and a few-mode fiber core (4).

Fundamental mode optical signal slave fundamental mode (LP)₀₁) The input port (P1) inputs the light source, and the fundamental mode of the light source is excited to generate a high-order mode (LP) through the core (3) of the multimode optical fiber₁₁) Forming different propagation phases, the fundamental mode (LP) in the core (2) of a single-mode optical fibre₀₁) Of the multimode optical fibre core (3) and a higher order mode (LP) output by the multimode optical fibre core (3)₁₁) When the high-order mode (LP) of the core (3) of the multimode optical fiber is increased₁₁) And a fundamental mode (LP) in the core (2) of the single-mode optical fibre₀₁) When the effective refractive index of the optical fiber is equal, a phase matching condition is achieved, and a fundamental mode (LP) is completed₀₁) Mode to higher order mode (LP)₁₁) To convert between them. A fundamental mode (LP) with the optical signal transmission₀₁) And a high order mode (LP)₁₁) The effective refractive indexes of the two modes are gradually inconsistent, the coupling effect tends to be mild, and finally the fundamental mode optical signal (LP)₀₁) Almost total power coupling into the core (3) of a multimode optical fibre in the higher-order modes (LP)₁₁) Among the modes, the high-order mode (LP)₁₁) Although the power of (A) is the greatest proportion, only the high-order mode (LP) is desired₁₁) Conversion, and cut-off of the few-mode fiber core (4) to perform mode filtering, so that the output port (P2) can obtain a high-order mode (LP)₁₁) Purer to achieve almost the required (LP) transfer of optical power₁₁) On the mode.

After the addition of a few-mode fiber core (4), the desired high-order mode (LP)₁₁) The power of the mode is obviously improved, and LP is further enhanced₁₁Power of a mode while reducing power of other modes;

herein, onlyIs to list LP₀₁To LP₁₁Switching modes; in practice, however, LP can be achieved by adjusting the values of the architectural parameters as described above₀₁To LP₁₂、LP₃₁And (4) converting the equal high-order mode.

It should be understood that the examples are for illustrative purposes only and are not intended to limit the scope of the present invention. It should be further understood that various changes and modifications of the present invention may occur to those skilled in the art after reading the teachings herein, and that such equivalents are intended to be covered by the appended claims.

Claims (5)

1. LP₀₁mode-LP₁₁Mode all-fiber mode conversion device, its characterized in that: adopt dislocation optical waveguide to connect and constitute mode conversion device, specifically include: a fiber core cladding (1), a single-mode fiber core (2), a multi-mode fiber core (3), a few-mode fiber core (4),

wherein:

a. the fiber core cladding (1) uniformly covers the fiber core, the radius is R1, and the length is L;

b. the single-mode optical fiber core (2) has the radius R2 and the length L1;

c. the multimode fiber core (3) has the radius R3 and the length L2;

d. the small-mode optical fiber core (4) has the radius R4 and the length L3;

e. the central axes of the single-mode optical fiber core (2), the multimode optical fiber core (3) and the few-mode optical fiber core (4) are parallel, the distance between the single-mode optical fiber core (2) and the central axis of the multimode optical fiber core (3) is D1, the distance between the few-mode optical fiber core (4) and the central axis of the multimode optical fiber core (3) is D2, and the central axes of the multimode optical fiber core (3) and the fiber core cladding (1) are consistent;

f. the refractive index n1 of the core cladding (1), the refractive indices of the single-mode optical fiber core (2), the multimode optical fiber core (3) and the few-mode optical fiber core (4) are all n2, and n1 is less than n 2.

2. An LP in accordance with claim 1₀₁mode-LP₁₁Mode all-fiber mode conversion device, its characterized in that: fundamental mode signal (LP)₀₁) Is input from a fundamental mode input port (P1)And a large number of high-order modes are excited and converted through the multimode optical fiber core (3), and a mode field passes through the few-mode optical fiber core (4) and is finally output from an output port (P2).

3. An LP in accordance with claim 1₀₁mode-LP₁₁Mode all-fiber mode conversion device, its characterized in that: along with the transmission of signals, the effective refractive index of a fundamental mode in the single-mode optical fiber core (2) is gradually reduced, the effective refractive index of a high-order mode output by the multimode optical fiber core (3) is increased, and when the effective refractive index of a certain high-order mode is equal to the effective refractive index of the fundamental mode, phase matching is completed, so that mode conversion is realized.

4. An LP in accordance with claim 1₀₁mode-LP₁₁Mode all-fiber mode conversion device, its characterized in that: the method comprises the steps of adjusting the length L1 of a single-mode optical fiber core (2), the radius R2 of a fundamental mode input port (P1) of the single-mode optical fiber core (2), the length L2 of a multimode optical fiber core (3), the radius R3 of the multimode optical fiber core (3), the length L3 of a few-mode optical fiber core (4), the radius R4 of an output port (P2) of the few-mode optical fiber core (4), the distance between the central axes of the single-mode optical fiber core (2) and the multimode optical fiber core (3) is D1, the distance between the central axes of the few-mode optical fiber core (4) and the multimode optical fiber core (3) is D2, the central axes of the multimode optical fiber core (3) and a core cladding (1) are consistent, and fundamental mode signals (LP) can be achieved₀₁) And converting to a higher order mode.

5. An LP in accordance with claim 1₀₁mode-LP₁₁Mode all-fiber mode conversion device, its characterized in that: the optical waveguide structure is round or rectangular; LP where the higher-order modes of inversion are not critical when using rectangular waveguides₁₁Mode, is quasi LP₁₁Mode(s).

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