BENDING-RESISTANT LOW-CROSSTALK PHOTONIC ORBITAL ANGULAR MOMENTUM FIBER WAVEGUIDE

Abstract

A bending-resistant low-crosstalk photonic orbital angular momentum (OAM) optical fiber waveguide. An optical fiber sequentially comprises, from the center to the outside, a first core layer (1), a second core layer (2), a first cladding layer (3), a second cladding layer (4), and a third cladding layer (5), wherein the third cladding layer (5) is the thickest, the first core layer (1) is the second thickest, and the first cladding layer (3) is the thinnest; the refractive index of the first cladding layer (3) is the lowest, the refractive index of the second cladding layer (4) is the second lowest, and the refractive index of the second core layer (2) is the highest. The waveguide structure can effectively regulate the output of different OAM modes, and an effective refractive index difference between modes is greater than 210.sup.4, the modes are easy to separate, and multiplexing and demultiplexing are facilitated.

Claims

1-10. (canceled)

11. A bending-resistant low-crosstalk photonic orbital angular momentum fiber waveguides, wherein the fiber sequentially consists of a first core layer, a second core layer, a first cladding layer, a second cladding layer, and a third cladding layer from the center outward, with the third cladding layer being the thickest, followed by the first core layer, and the first cladding layer being the thinnest; the refractive index of the first cladding layer is the smallest, followed by the second cladding layer, and the refractive index of the second core layer is the largest; the relationship function relationship A between the radii r.sub.1 of the first core layer and r.sub.2 of the second core layer satisfies A=k.sub.110log(r.sub.2/r.sub.1)/(L2), where k.sub.1 ranges from 0.36 to 1.52, L ranges from 3 to 9, and A ranges from 0.06446 to 1.61151; the relationship function B between the radius r.sub.3 of the first cladding layer and the radius r.sub.2 of the second core layer satisfies B=k.sub.210log (r.sub.3/r.sub.2)(L2), where k.sub.2 ranges from 0.66 to 1.37, L ranges from 2 to 9, and B ranges from 0 to 3.4649;the refractive index difference between the first core layer refractive index n.sub.1 and the third cladding layer refractive index n.sub.5 is from 0.00029 to 0.01603;the refractive index difference between the second core layer refractive index n.sub.2 and the third cladding layer refractive index n.sub.5 is from 0.017485 to 0.037885; the refractive index difference between the first cladding layer refractive index n.sub.3 and the third cladding layer refractive index n.sub.5 is from 0.005 to 0.0153; the refractive index difference between the second cladding layer refractive index n.sub.4 and the third cladding layer refractive index n.sub.5 is from 0.005 to 0.0153; the refractive index curve of the second core layer refractive index n.sub.2 gradually changes and satisfies the refractive index profile distribution function: $n\left(r\right)={n_2\left[1-2{\left(\frac{r-r_1}{\frac{d}{2}}\right)}^g\right]}^{\frac{1}{2}},\mathrm{where}{r}_{1}r{r}_2,r_a=\left(r_1+r_2\right)/2,d=r_2-r_1,=\frac{n_2^2-n_5^2}{2n_2^2},$ g is the refractive index profile distribution parameter, and g ranges from 2 to 9.

12. The bending-resistant low-crosstalk photonic orbital angular momentum fiber waveguides as claimed in claim 11, wherein the value of g is 2, 3, 2, 3, or 5.

13. The bending-resistant low-crosstalk photonic orbital angular momentum fiber waveguides as claimed in claim 11, the fiber can control the output of four different-order OAM modes within the wavelength range of 1530 nm to 1565 nm for stable transmission, including OAM-0 order, OAM-1 order, OAM-2 order, and OAM-3 order, and the effective refractive index difference between each OAM mode is greater than 1.5210.sup.4.

14. The bending-resistant low-crosstalk photonic orbital angular momentum fiber waveguides as claimed in claim 13, wherein the bending loss of each OAM mode of the fiber at a wavelength of 1550 nm is small, and the macro-bending loss of bending 1 circle at R5 mm is less than or equal to 0.50 dB; the crosstalk between the OAM-0 order and OAM-1 order modes of the fiber is less than 9 dB/80 km, the crosstalk between the OAM-1 order and OAM-2 order modes is less than 16 dB/80 km, the crosstalk between the OAM-1 order and OAM-2 order modes is less than 15 dB/80 km, and the crosstalk between the OAM-1 order and OAM-3 order modes is less than 25 dB/80 km.

15. The bending-resistant low-crosstalk photonic orbital angular momentum fiber waveguides as claimed in claim 13, wherein the value of g is 2, 3, 2, 3, or 5.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] To provide a clearer understanding of the technical solution of the embodiments of the present disclosure, a brief introduction to the drawings required in the embodiments will be presented below. The following drawings only illustrate certain embodiments of the present disclosure and should not be construed as limiting the scope. Ordinary skilled artisans in the field can obtain other relevant drawings based on these drawings without exercising creative labor.

[0042] After reading the detailed description of the embodiments disclosed herein in conjunction with the following drawings, a better understanding of the features and advantages of the present disclosure can be achieved. In the drawings, the components may not be drawn to scale, and components with similar relevant characteristics or features may have the same or similar reference numerals.

[0043] FIG. 1 is a schematic diagram of the refractive index profile structure of the fiber waveguide of the present disclosure.

[0044] FIG. 2 is a schematic diagram of the end face structure of the fiber waveguide of the present disclosure.

[0045] Wherein: 1First core layer, 2Second core layer, 3First cladding layer, 4Second cladding layer, 5Third cladding layer, 6Inner coating, 7Outer coating.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0046] The following provides a detailed description of the present disclosure with reference to the drawings and specific embodiments. Aspects described in conjunction with the drawings and specific embodiments are exemplary and should not be construed as limiting the scope of the present disclosure.

[0047] As shown in FIGS. 1 and 2, the present disclosure provides a fiber waveguide for photon orbital angular momentum (OAM) transmission. The fiber waveguide is composed of two core layers, three cladding layers, and coating layers. Specifically, from the center outward, it consists of the first core layer (r.sub.1), the second core layer (r.sub.2), the first cladding layer (r.sub.3), the second cladding layer (r.sub.4), and the third cladding layer (r.sub.5), as well as coating layers outside the third cladding layer, composed of an inner coating (6) and an outer coating (7) as shown in FIG. 2. The third cladding layer is the thickest, followed by the first core layer, and the first cladding layer is the thinnest. The refractive index of the first cladding layer is the smallest, followed by the second cladding layer.

[0048] The relationship between the radii r.sub.1 and r.sub.2 of the first and second core layers satisfies the function A=k.sub.110log(r.sub.2/r.sub.1)/(L2), where k.sub.1 ranges from 0.36 to 1.52, L ranges from 3 to 9, and A ranges from 0.06446 to 1.61151. The relationship between the radius r.sub.3 of the first cladding layer and the radius r.sub.2 of the second core layer satisfies the function B=k.sub.210log (r.sub.3/r.sub.2)(L2), where k.sub.2 ranges from 0.66 to 1.37, L ranges from 2 to 9, and B ranges from 0 to 3.4649. The refractive index difference between the first core layer n.sub.1 and the third cladding layer n.sub.5 ranges from 0.00029 to 0.01603. The refractive index difference between the second core layer n.sub.2 and the third cladding layer n.sub.5 is 0.017485. The refractive index difference between the first cladding layer n.sub.3 and the third cladding layer n.sub.5 ranges from 0.005 to 0.0153. The second cladding layer refractive index difference n.sub.4 and the third cladding layer refractive index n.sub.5 range from 0.005 to 0.0153. The refractive index of the second core layer n.sub.2 has a radial gradient, following the refractive index profile distribution function formula

[00003]$n\left(r\right)={n_2\left[1-2{\left(\frac{r-r_1}{\frac{d}{2}}\right)}^g\right]}^{\frac{1}{2}},\mathrm{where}{r}_{1}r{r}_2,r_a=\left(r_1+r_2\right)/2,d=r_2-r_1,=\frac{n_2^2-n_5^2}{2n_2^2},$

and g is the refractive index profile distribution parameter. The refractive index profile distribution parameter g of the second core layer refractive index n.sub.2 ranges from 2 to 9, preferably g=2, 3, 2, 3, or 5.

[0049] The fiber waveguide for photon orbital angular momentum transmission can control the output of four different-order OAM modes within the wavelength range of 1530 nm to 1565 nm to achieve stable transmission, including OAM-0, OAM-1, OAM-2, and OAM-3 modes. The effective refractive index difference between each OAM mode is greater than 1.5210-4. The bending loss of each OAM mode of the fiber waveguide at a wavelength of 1550 nm is small, with a macro-bending loss of less than or equal to 0.50 dB for one loop at an R5 mm bend. The crosstalk between OAM-0 and OAM-1 modes is less than 9 dB/80 km, between OAM-1 and OAM-2 modes is less than 16 dB/80 km, between OAM-1 and OAM-2 modes is less than 15 dB/80 km, and between OAM-1 and OAM-3 modes is less than 25 dB/80 km.

Example 1

[0050] The present disclosure provides a fiber waveguide for photon orbital angular momentum (OAM) transmission, which consists of two core layers, three cladding layers, and coating layers. The characteristics are as follows: from the center outward, there are the first core layer (r.sub.1), the second core layer (r.sub.2), the first cladding layer (r.sub.3), the second cladding layer (r.sub.4), and the third cladding layer (r.sub.5). The coating layer outside the third cladding layer is composed of an inner coating and an outer coating, which are cured by ultraviolet light-cured organic resin. The relationship between the radii r.sub.1 and 12 of the first and second core layers satisfies the function A=k.sub.110log(r.sub.2/r.sub.1)/(L2), where k.sub.1=0.36, A=0.06446, and L ranges from 3 to 9. The relationship between the radius r.sub.3 of the first cladding layer and the radius r.sub.2 of the second core layer satisfies the function B=k.sub.210log(r.sub.3/r.sub.2)(L2), where k.sub.2=0.66, B=0.3131, and L ranges from 2 to 9. The refractive index difference between the first core layer n.sub.1 and the third cladding layer n.sub.5 is 0.00029. The refractive index difference between the second core layer n.sub.2 and the third cladding layer n.sub.5 is 0.017485. The refractive index difference between the first cladding layer n.sub.3 and the third cladding layer n.sub.5 is 0.005, and the structure of this cladding layer waveguide has quantum tunneling effects, which can control the mode loss characteristics. The refractive index difference between the second cladding layer n.sub.4 and the third cladding layer n.sub.5 is 0.00. The refractive index profile distribution function of the second core layer's annular core gradient is given by the formula

[00004]$n\left(r\right)={n_2\left[1-2{\left(\frac{r-r_1}{\frac{d}{2}}\right)}^g\right]}^{\frac{1}{2}},\mathrm{where}{r}_{1}r{r}_2,r_a=\left(r_1+r_2\right)/2,d=r_2-r_1,=\frac{n_2^2-n_5^2}{2n_2^2},$

and g is the refractive index profile distribution parameter. The refractive index curve of the second core layer n.sub.2 varies and satisfies the refractive index profile distribution function, with a value of g=2. The fiber waveguide for photon orbital angular momentum transmission can control four different-order OAM modes within the wavelength range of 1530 nm to 1565 nm to achieve stable transmission, including OAM-0, OAM-1, OAM-2, and OAM-3, where the effective refractive index difference between each OAM mode is greater than 1.5310-4 (refer to Table 1). The bending loss of each OAM mode of the fiber waveguide at a wavelength of 1550 nm is small, with a macro-bending loss of less than or equal to 0.50 dB for one loop at an R5 mm bend (refer to Table 1). The crosstalk between OAM-0 and OAM-1 modes is less than 9 dB/80 km, between OAM-1 and OAM-2 modes is less than 16 dB/80 km, between OAM-1 and OAM-2 modes is less than 15 dB/80 km, and between OAM-1 and OAM-3 modes is less than 25 dB/80 km (refer to Table 1).

Example 2

[0051] The present disclosure provides a fiber waveguide for photon orbital angular momentum (OAM) transmission, which consists of two core layers, three cladding layers, and coating layers. The characteristics are as follows: from the center outward, there are the first core layer (r.sub.1), the second core layer (r.sub.2), the first cladding layer (r.sub.3), the second cladding layer (r.sub.4), and the third cladding layer (r.sub.5), as well as coating layers outside the third cladding layer. The relationship between the radii r.sub.1 and r.sub.2 of the first and second core layers satisfies the function A=k.sub.110log(r.sub.2/r.sub.1)/(L2), where k.sub.1=1.52, A=1.61151, and L ranges from 3 to 9. The relationship between the radius r.sub.3 of the first cladding layer and the radius 12 of the second core layer satisfies the function B=k.sub.210log(r.sub.3/r.sub.2)(L2), where k.sub.2=1.37, B=3.4649, and L ranges from 2 to 9. The refractive index difference between the first core layer n.sub.1 and the third cladding layer n.sub.5 is 0.01603. The refractive index difference between the second core layer n.sub.2 and the third cladding layer n.sub.5 is 0.037885. The refractive index difference between the first cladding layer n.sub.3 and the third cladding layer n.sub.5 is 0.0153, and the structure of this cladding layer waveguide has quantum tunneling effects, which can control the mode loss characteristics. The refractive index difference between the second cladding layer n.sub.4 and the third cladding layer n.sub.5 is 0.0153. The refractive index profile distribution function of the second core layer's annular core gradient is given by the formula

[00005]$n\left(r\right)={n_2\left[1-2{\left(\frac{r-r_1}{\frac{d}{2}}\right)}^g\right]}^{\frac{1}{2}},\mathrm{where}{r}_{1}r{r}_2,r_a=\left(r_1+r_2\right)/2,d=r_2-r_1,=\frac{n_2^2-n_5^2}{2n_2^2},$

and g is the refractive index profile distribution parameter. The refractive index curve of the second core layer n.sub.2 varies and satisfies the refractive index profile distribution function, with a value of g=3. The fiber waveguide for photon orbital angular momentum transmission can control four different-order OAM modes within the wavelength range of 1530 nm to 1565 nm to achieve stable transmission, including OAM-0, OAM-1, OAM-2, and OAM-3, where the effective refractive index difference between each OAM mode is greater than 1.5210-4 (refer to Table 1). The bending loss of each OAM mode of the fiber waveguide at a wavelength of 1550 nm is small, with a macro-bending loss of less than or equal to 0.37 dB for one loop at an R5 mm bend (refer to Table 1). The crosstalk between OAM-0 and OAM-1 modes is less than 9 dB/80 km, between OAM-1 and OAM-2 modes is less than 16 dB/80 km, between OAM-1 and OAM-2 modes is less than 15 dB/80 km, and between OAM-1 and OAM-3 modes is less than 25 dB/80 km (refer to Table 1).

Example 3

[0052] The present disclosure provides a fiber waveguide for photon orbital angular momentum (OAM) transmission, which consists of two core layers, three cladding layers, and coating layers. The characteristics are as follows: from the center outward, there are the first core layer (r.sub.1), the second core layer (r.sub.2), the first cladding layer (r.sub.3), the second cladding layer (r.sub.4), and the third cladding layer (r.sub.5), as well as coating layers outside the third cladding layer. The relationship between the radii r.sub.1 and r.sub.2 of the first and second core layers satisfies the function A=k.sub.110log(r.sub.2/r.sub.1)/(L2), where k.sub.1=1.01, A=0.8057, and L ranges from 3 to 9. The relationship between the radius r.sub.3 of the first cladding layer and the radius r.sub.2 of the second core layer satisfies the function B=k.sub.210log(r.sub.3/r.sub.2)(L2), where k.sub.2=1.12, B=0.6281, and L ranges from 3 to 9. The refractive index difference between the first core layer n.sub.1 and the third cladding layer n.sub.5 is 0.00949. The refractive index difference between the second core layer n.sub.2 and the third cladding layer n.sub.5 is 0.029146. The refractive index difference between the first cladding layer n.sub.3 and the third cladding layer n.sub.5 is 0.01093, and the structure of this cladding layer waveguide has quantum tunneling effects, which can control the mode loss characteristics. The refractive index difference between the second cladding layer n.sub.4 and the third cladding layer n.sub.5 is 0.00729. The refractive index profile distribution function of the second core layer's annular core gradient is given by the formula

[00006]$n\left(r\right)={n_2\left[1-2{\left(\frac{r-r_1}{\frac{d}{2}}\right)}^g\right]}^{\frac{1}{2}},\mathrm{where}{r}_{1}r{r}_2,r_a=\left(r_1+r_2\right)/2,d=r_2-r_1,=\frac{n_2^2-n_5^2}{2n_2^2},$

and g is the refractive index profile distribution parameter. The refractive index curve of the second core layer n.sub.2 varies and satisfies the refractive index profile distribution function, with a value of g=9. The fiber waveguide for photon orbital angular momentum transmission can control four different-order OAM modes within the wavelength range of 1530 nm to 1565 nm to achieve stable transmission, including OAM-0, OAM-1, OAM-2, and OAM-3, where the effective refractive index difference between each OAM mode is greater than 1.5210-4 (refer to Table 1). The bending loss of each OAM mode of the fiber waveguide at a wavelength of 1550 nm is small, with a macro-bending loss of less than or equal to 0.43 dB for one loop at an R5 mm bend (refer to Table 1). The crosstalk between OAM-0 and OAM-1 modes is less than 9 dB/80 km, between OAM-1 and OAM-2 modes is less than 16 dB/80 km, between OAM-1 and OAM-2 modes is less than 15 dB/80 km, and between OAM-1 and OAM-3 modes is less than 25 dB/80 km (refer to Table 1).

Example 4

[0053] The present disclosure provides a photonic orbital angular momentum (OAM) optical fiber waveguide, which is composed of two core layers, three cladding layers, and a coating layer. The features include: from the center outward, the structure consists of the first core layer (r.sub.1), the second core layer (r.sub.2), the first cladding layer (r.sub.3), the second cladding layer (r.sub.4), the third cladding layer (r.sub.5), and the coating layer outside the third cladding layer. The relationship function between the radius r.sub.1 of the first core layer and the radius r.sub.2 of the second core layer is given by A=k.sub.110log(r.sub.2/r.sub.1)/(L2), where k.sub.1=0.96, A=0.5371, and L is an integer ranging from 3 to 9. The relationship between the radius r.sub.3 of the first cladding layer and the radius 12 of the second core layer is described by the function B=k.sub.210log(r.sub.3/r.sub.2)(L2), where k.sub.2=0.987, B=0.9422, and Lis an integer ranging from 2 to 9. The refractive index difference between the first core layer with refractive index n.sub.1 and the third cladding layer with refractive index n.sub.5 is 0.01392. The refractive index difference between the second core layer with refractive index n.sub.2 and the third cladding layer with refractive index n.sub.5 is 0.032056. The refractive index difference between the first cladding layer with refractive index n.sub.3 and the third cladding layer with refractive index n.sub.5 is 0.011953. The refractive index difference between the second cladding layer with refractive index n.sub.4 and the third cladding layer with refractive index n.sub.5 is 0.009651. The refractive index profile distribution function of the second core layer's annular core gradient is given by

[00007]$n\left(r\right)={n_2\left[1-2{\left(\frac{r-r_1}{\frac{d}{2}}\right)}^g\right]}^{\frac{1}{2}},\mathrm{where}{r}_{1}r{r}_2,r_a=\left(r_1+r_2\right)/2,d=r_2-r_1,=\frac{n_2^2-n_5^2}{2n_2^2},$

and g is the refractive index profile distribution parameter. The refractive index curve of the second core layer n.sub.2 varies and satisfies the refractive index profile distribution function, with a value of g=2. The photonic orbital angular momentum optical fiber waveguide can control the output of four different orders of OAM modes within the wavelength range of 1530 nm to 1565 nm, achieving stable transmission of OAM-0th, OAM-1st, OAM-2nd, and OAM-3rd orders. The effective refractive index difference between each OAM mode is greater than 1.5210-4. The bending loss of each OAM mode at a wavelength of 1550 nm is small, with macro bending loss of R5 mm less than or equal to 0.45 dB. The crosstalk between OAM-0th and OAM-1st modes is less than 9 dB/80 km, between OAM-1st and OAM-2nd modes is less than 16 dB/80 km, between OAM-1st and OAM-2nd modes is less than 15 dB/80 km, and between OAM-1st and OAM-3rd modes is less than 25 dB/80 km.

Example 5

[0054] The present disclosure provides a photonic orbital angular momentum (OAM) optical fiber waveguide, which is composed of two core layers, three cladding layers, and a coating layer. The features include: from the center outward, the structure consists of the first core layer (r.sub.1), the second core layer (r.sub.2), the first cladding layer (r.sub.3), the second cladding layer (r.sub.4), the third cladding layer (r.sub.5), and the coating layer outside the third cladding layer. The relationship function between the radius r.sub.1 of the first core layer and the radius r.sub.2 of the second core layer is given by A=k.sub.110log(r.sub.2/r.sub.1)/(L2), where k.sub.1=1.12, A=0.3223, and L is an integer ranging from 3 to 9. The relationship between the radius r.sub.3 of the first cladding layer and the radius r.sub.2 of the second core layer is described by the function B=k.sub.210log(r.sub.3/r.sub.2)(L2), where k.sub.2=1.32, L=2, and B=0. The refractive index difference between the first core layer with refractive index n.sub.1 and the third cladding layer with refractive index n.sub.5 is 0.01506. The refractive index difference between the second core layer with refractive index n.sub.2 and the third cladding layer with refractive index n.sub.5 is 0.027399. The refractive index difference between the first cladding layer with refractive index n.sub.3 and the third cladding layer with refractive index n.sub.5 is 0; The refractive index difference between the second cladding layer with refractive index n.sub.4 and the third cladding layer with refractive index n.sub.5 is 0.00939. The refractive index profile distribution function of the second core layer's annular core gradient is given by

[00008]$n\left(r\right)={n_2\left[1-2{\left(\frac{r-r_1}{\frac{d}{2}}\right)}^g\right]}^{\frac{1}{2}},\mathrm{where}{r}_{1}r{r}_2,r_a=\left(r_1+r_2\right)/2,d=r_2-r_1,=\frac{n_2^2-n_5^2}{2n_2^2},$

and g is the refractive index profile distribution parameter. The refractive index curve of the second core layer n.sub.2 varies and satisfies the refractive index profile distribution function, with a value of g=5. The photonic orbital angular momentum optical fiber waveguide can control the output of four different orders of OAM modes within the wavelength range of 1530 nm to 1565 nm, achieving stable transmission of OAM-0th, OAM-1st, OAM-2nd, and OAM-3rd orders. The effective refractive index difference between each OAM mode is greater than 1.5210-4. The bending loss of each OAM mode at a wavelength of 1550 nm is small, with macro bending loss of R5 mm less than or equal to 0.45 dB. The crosstalk between OAM-0th and OAM-1st modes is less than 9 dB/80 km, between OAM-1st and OAM-2nd modes is less than 16 dB/80 km, between OAM-1st and OAM-2nd modes is less than 15 dB/80 km, and between OAM-1st and OAM-3rd modes is less than 25 dB/80 km.

Example 6

[0055] The present disclosure provides a photonic orbital angular momentum (OAM) optical fiber waveguide, which is composed of two core layers, three cladding layers, and a coating layer. The features include: from the center outward, the structure consists of the first core layer (r.sub.1), the second core layer (r.sub.2), the first cladding layer (r.sub.3), the second cladding layer (r.sub.4), the third cladding layer (r.sub.5), and the coating layer outside the third cladding layer. The relationship function between the radius r.sub.1 of the first core layer and the radius r.sub.2 of the second core layer is given by A=k.sub.110log(r.sub.2/r.sub.1)/(L2), where k.sub.1=0.837, A=0.16115, and L is an integer ranging from 3 to 9. The relationship between the radius r.sub.3 of the first cladding layer and the radius r.sub.2 of the second core layer is described by the function B=k.sub.210log(r.sub.3/r.sub.2)(L2), where k.sub.2=0.763, B=2.9185, and Lis an integer ranging from 2 to 9. The refractive index difference between the first core layer with refractive index n.sub.1 and the third cladding layer with refractive index n.sub.5 is 0.01039. The refractive index difference between the second core layer with refractive index n.sub.2 and the third cladding layer with refractive index n.sub.5 is 0.035065. The refractive index difference between the first cladding layer with refractive index n.sub.3 and the third cladding layer with refractive index n.sub.5 is 0.00796. The refractive index difference between the second cladding layer with refractive index n.sub.4 and the third cladding layer with refractive index n.sub.5 is 0.00856. The refractive index profile distribution function of the second core layer's annular core gradient is given by

[00009]$n\left(r\right)={n_2\left[1-2{\left(\frac{r-r_1}{\frac{d}{2}}\right)}^g\right]}^{\frac{1}{2}},\mathrm{where}{r}_{1}r{r}_2,r_a=\left(r_1+r_2\right)/2,d=r_2-r_1,=\frac{n_2^2-n_5^2}{2n_2^2},$

refractive index curve of the second core layer n.sub.2 varies and satisfies the refractive index profile distribution function, with a value of g=3. The photonic orbital angular momentum optical fiber waveguide can control the output of four different orders of OAM modes within the wavelength range of 1530 nm to 1565 nm, achieving stable transmission of OAM-0th, OAM-1st, OAM-2nd, and OAM-3rd orders. The effective refractive index difference between each OAM mode is greater than 1.5210-4. The bending loss of each OAM mode at a wavelength of 1550 nm is small, with macro bending loss of R5 mm less than or equal to 0.46 dB. The crosstalk between OAM-0th and OAM-1st modes is less than 9 dB/80 km, between OAM-1st and OAM-2nd modes is less than 16 dB/80 km, between OAM-1st and OAM-2nd modes is less than 15 dB/80 km, and between OAM-1st and OAM-3rd modes is less than 25 dB/80 km.

[0056] The main performance indicators of the fiber optic waveguides in the above implementation examples are listed in Table 1. Table 1: Main performance indicators of fiber optic waveguides in implementation examples.

TABLE-US-00001 Example Example Example Example Example Example Item Mode 1 2 3 4 5 6 Crosstalk OAM0-OAM1 10.2 12.3 11.5 9.7 10.9 11.8 (dB/80 km) OAM1-OAM2 16.3 17.6 17.1 16.5 16.6 16.9 OAM2-OAM3 15.8 16.2 15.9 16.2 16.5 15.7 OAM1-OAM3 25.5 26.7 26.1 25.3 26.4 25.2 Macro- OAM0 0.50 0.36 0.43 0.45 0.38 0.46 Bending OAM 1 0.32 0.25 0.3 0.33 0.29 0.25 Loss (dB) OAM 2 0.39 0.37 0.33 0.4 0.45 0.36 @1550(R OAM 3 0.29 0.26 0.35 0.43 0.39 0.42 5*1 loop)

[0057] The various embodiments in this specification are described progressively, with each embodiment focusing on the differences from other embodiments. The similarities and identical parts among the embodiments can be referenced interchangeably.

[0058] The description provided herein is intended to enable any person skilled in the art to make or use the present disclosure. Modifications to the present disclosure will be apparent to those skilled in the art, and the universally applicable principles defined herein can be applied to other variations without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the examples and designs described herein but should be granted the broadest scope consistent with the principles and novel features disclosed herein.

[0059] The above-described embodiments are merely exemplary of the present application and should not be construed as limiting the application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present application should be included within the scope of protection of the present application.