Broadband polarization beam splitter/combiner based on gradient waveguide directional coupler

Abstract

A broadband polarization beam splitter/combiner based on a gradient waveguide directional coupler, comprises a gradient waveguide directional coupler, a beam combining end (1), a curved waveguide (5), a TE mode end (6) and a TM mode end (7). The coupler consists of a straight end gradient waveguide (2) and a serial end gradient waveguide (3). The trend of change of the gradient waveguide (2) is opposite to the gradient waveguide (3), and a gap is provided between the gradient waveguide (2) and the gradient waveguide (3). The beam combining end (1) is connected with one end of the gradient waveguide (2), the other end of the gradient waveguide (2) is connected with one end of the curved waveguide (5), the other end of the curved waveguide (5) is connected with the TE end (6), and the waveguide (3) is connected with the TM end (7).

Claims

1. A broadband polarization beam splitter/combiner based on gradient waveguide directional coupler, configured to split a light into a light of a transverse electric mode TE mode and a light of a transverse magnetic mode TM mode, or to combine a light of a transverse electric mode TE mode and a light of a transverse magnetic mode TM mode into a light, consists of a gradient waveguide directional coupler, a beam combining end (1), a curved waveguide (5), a transverse electric mode TE end (6) and a transverse magnetic mode TM end (7), the gradient waveguide directional coupler consists of a straight end gradient waveguide (2) and a serial end gradient waveguide (3), the trend of change of the straight end gradient waveguide (2) is opposite to that of the serial end gradient waveguide (3), and a gap (4) is provided between the straight end gradient waveguide (2) and the serial end gradient waveguide (3), the beam combining end (1) is connected with one end of the straight end gradient waveguide (2), the other end of the straight end gradient waveguide (2) is connected with one end of the curved waveguide (5), the other end of the curved waveguide (5) is connected with the transverse electric mode TE end (6), and the serial end gradient waveguide (3) is connected with the transverse magnetic mode TM end (7).

2. The broadband polarization beam splitter/combiner of claim 1, wherein when the broadband polarization beam splitter/combiner is used as a beam splitter, a light is incident from the beam combining end (1), a light of TE mode exits from the transverse electric mode TE end (6), and a light of TM mode exits from the transverse magnetic mode TM end (7).

3. The broadband polarization beam splitter/combiner of claim 1, wherein when the broadband polarization beam splitter/combiner is used as a beam combiner, a light of TE mode is incident from the transverse electric mode TE end (6), a light of TM mode is incident from the transverse magnetic mode TM end (7), and a light resulting from combining the two polarized light exits from the beam combining end (1).

4. The broadband polarization beam splitter/combiner of claim 1, wherein the width of the straight end gradient waveguide (2) is tapered, and the width of the serial end gradient waveguide (3) is increased.

5. The broadband polarization beam splitter/combiner of claim 4, wherein the width of the straight end gradient waveguide (2) is tapered from [0.5, 1] m to [0.3, 0.45] m, the width of the serial end gradient waveguide (3) is increased from [0.3, 0.45] m to [0.5, 1] m, and the gap is provided between the straight end gradient waveguide (2) and the serial end gradient waveguide (3).

6. The broadband polarization beam of claim 5, wherein the width of the straight end gradient waveguide (2) is tapered from [0.6, 0.9] m to [0.35, 0.45] m, the width of the serial end gradient waveguide (3) is increased from [0.35, 0.45] m to [0.6, 0.9] m, and the gap is provided between the straight end gradient waveguide (2) and the serial end gradient waveguide (3).

7. The broadband polarization beam of claim 1, wherein the width of the straight end gradient waveguide (2) is increased, and the width of the serial end gradient waveguide (3) is tapered.

8. The broadband polarization beam of claim 7, wherein the width of the straight end gradient waveguide (2) is increased from [0.3, 0.45] m to [0.5, 1] m, the width of the serial end gradient waveguide (3) is tapered from [0.5, 1] m to [0.3, 0.45] and the gap is provided between the straight end gradient waveguide (2) and the serial end gradient waveguide (3).

9. The broadband polarization beam of claim 8, wherein the width of the straight end gradient waveguide (2) is increased from [0.35, 0.45] m to [0.6, 0.9] m, the width of the serial end gradient waveguide (3) is tapered from [0.6, 0.9] m to [0.35, 0.45] m, and the gap is provided between the straight end gradient waveguide (2) and the serial end gradient waveguide (3).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 schematically shows a structure of a conventional polarization beam splitter.

(2) FIG. 2 schematically shows a structure of a broadband polarization beam splitter/combiner based on gradient waveguide directional coupler in accordance with example 1 of the invention.

(3) FIG. 3 schematically shows a structure of a broadband polarization beam splitter/combiner based on gradient waveguide directional coupler in accordance with example 2 of the invention.

REFERENCE NUMBERS

(4) 1beam combining end, 2straight end gradient waveguide, 3serial end gradient waveguide, 4gap, 5bending waveguide, 6transverse electric mode TE end, 7transverse magnetic mode TM end.

DETAILED DESCRIPTION OF THE INVENTION

(5) The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

(6) In order to widen the range of operating wavelength of the polarization beam splitter without increasing the complexity of the device, the embodiments of the present invention provides a broadband polarization beam splitter/combiner based on gradient waveguide directional coupler.

(7) As shown in FIG. 2 and FIG. 3, the broadband polarization beam splitter/combiner of the invention comprises a gradient waveguide directional coupler, a beam combining end 1, a curved waveguide 5, a transverse electric mode TE end 6 and a transverse magnetic mode TM end 7. The gradient waveguide directional coupler consists of a straight end gradient waveguide 2 and a serial end gradient waveguide 3, the trend of change of the straight end gradient waveguide 2 is opposite to that of the serial end gradient waveguide 3, and a gap 4 is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3. The beam combining end 1 is connected with one end of the straight end gradient waveguide 2, the other end of the straight end gradient waveguide 2 is connected with one end of the curved waveguide 5, the other end of the curved waveguide 5 is connected with the transverse electric mode TE end 6, and the serial end gradient waveguide 3 is connected with the transverse magnetic mode TM end 7.

(8) When the broadband polarization beam splitter/combiner is used as a beam splitter, a light is incident from the beam combining end 1, a light of TE mode exits from the transverse electric mode TE end 6, and a light of TM mode exits from the transverse magnetic mode TM end 7.

(9) When the broadband polarization beam splitter/combiner is used as a beam combiner, a light of TE mode is incident from the transverse electric mode TE end 6, a light of TM mode is incident from the transverse magnetic mode TM end 7, and a light resulting from combining the two polarized light exits from the beam combining end 1.

(10) In particular, the width of the straight end gradient waveguide 2 is tapered from [0.5, 1] m to [0.3, 0.45] m, the width of the serial end gradient waveguide 3 is increased from [0.3, 0.45] m to [0.5, 1] m, and a gap is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3.

(11) Alternatively, the width of the straight end gradient waveguide 2 is increased from [0.3, 0.45] m to [0.5, 1] m, the width of the serial end gradient waveguide 3 is tapered from [0.5, 1] m to [0.3, 0.45] m, and the gap is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3.

(12) Further, the width of the straight end gradient waveguide 2 is tapered from [0.6, 0.9] m to [0.35, 0.45] m, the width of the serial end gradient waveguide 3 is increased from [0.35, 0.45] m to [0.6, 0.9] m, and the gap is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3.

(13) Alternatively, the width of the straight end gradient waveguide 2 is increased from [0.35, 0.45] m to [0.6, 0.9] m, the width of the serial end gradient waveguide 3 is tapered from [0.6, 0.9] m to [0.35, 0.45] m, and the gap is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3.

(14) The following is a detailed description in correction with 12 specific examples.

Example 1

(15) As shown in FIG. 2, Example 1 provides a broadband polarization beam splitter/combiner based on gradient waveguide directional coupler. The broadband polarization beam splitter/combiner of the invention comprises a gradient waveguide directional coupler, a beam combining end 1, a curved waveguide 5, a transverse electric mode TE end 6 and a transverse magnetic mode TM end 7. The gradient waveguide directional coupler consists of a straight end gradient waveguide 2 and a serial end gradient waveguide 3. The width of the straight end gradient waveguide 2 is tapered from 0.5 m to 0.3 m, the width of the serial end gradient waveguide 3 is increased from 0.3 m to 0.5 m, and a gap 4 is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3. The beam combining end 1 is connected with one end of the straight end gradient waveguide 2, the other end of the straight end gradient waveguide 2 is connected with one end of the curved waveguide 5, the other end of the curved waveguide 5 is connected with the transverse electric mode TE end 6, and the serial end gradient waveguide 3 is connected with the transverse magnetic mode TM end 7.

(16) When the broadband polarization beam splitter/combiner is used as a beam splitter, a light is incident from the beam combining end 1, a light of TE mode exits from the transverse electric mode TE end 6, and a light of TM mode exits from the transverse magnetic mode TM end 7.

(17) When the broadband polarization beam splitter/combiner is used as a beam combiner, a light of TE mode is incident from the transverse electric mode TE end 6, a light of TM mode is incident from the transverse magnetic mode TM end 7, and a light resulting from combining the two polarized light exits from the beam combining end 1.

Example 2

(18) As shown in FIG. 3, Example 2 provides a broadband polarization beam splitter/combiner based on gradient waveguide directional coupler. The broadband polarization beam splitter/combiner of the invention comprises a gradient waveguide directional coupler, a beam combining end 1, a curved waveguide 5, a transverse electric mode TE end 6 and a transverse magnetic mode TM end 7. The gradient waveguide directional coupler consists of a straight end gradient waveguide 2 and a serial end gradient waveguide 3, The width of the straight end gradient waveguide 2 is increased from 0.3 m to 0.5 m, the width of the serial end gradient waveguide 3 is tapered from 0.5 m to 0.3 m, and a gap 4 is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3. The beam combining end 1 is connected with one end of the straight end gradient waveguide 2, the other end of the straight end gradient waveguide 2 is connected with one end of the curved waveguide 5, the other end of the curved waveguide 5 is connected with the transverse electric mode TE end 6, and the serial end gradient waveguide 3 is connected with the transverse magnetic mode TM end 7.

(19) When the broadband polarization beam splitter/combiner is used as a beam splitter, a light is incident from the beam combining end 1, a light of TE mode exits from the transverse electric mode TE end 6, and a light of TM mode exits from the transverse magnetic mode TM end 7.

(20) When the broadband polarization beam splitter/combiner is used as a beam combiner, a light of TE mode is incident from the transverse electric mode TE end 6, a light of TM mode is incident from the transverse magnetic mode TM end 7, and a light resulting from combining the two polarized light exits from the beam combining end 1.

Example 3

(21) As shown in FIG. 2, Example 3 provides a broadband polarization beam splitter/combiner based on gradient waveguide directional coupler. The broadband polarization beam splitter/combiner of the invention comprises a gradient waveguide directional coupler, a beam combining end 1, a curved waveguide 5, a transverse electric mode TE end 6 and a transverse magnetic mode TM end 7. The gradient waveguide directional coupler consists of a straight end gradient waveguide 2 and a serial end gradient waveguide 3. The width of the straight end gradient waveguide 2 is tapered from 0.6 m to 0.35 m, the width of the serial end gradient waveguide 3 is increased from 0.35 m to 0.6 m, and a gap 4 is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3. The beam combining end 1 is connected with one end of the straight end gradient waveguide 2, the other end of the straight end gradient waveguide 2 is connected with one end of the curved waveguide 5, the other end of the curved waveguide 5 is connected with the transverse electric mode TE end 6, and the serial end gradient waveguide 3 is connected with the transverse magnetic mode TM end 7.

(22) When the broadband polarization beam splitter/combiner is used as a beam splitter, a light is incident from the beam combining end 1, a light of TE mode exits from the transverse electric mode TE end 6, and a light of TM mode exits from the transverse magnetic mode TM end 7.

(23) When the broadband polarization beam splitter/combiner is used as a beam combiner, a light of TE mode is incident from the transverse electric mode TE end 6, a light of TM mode is incident from the transverse magnetic mode TM end 7, and a light resulting from combining the two polarized light exits from the beam combining end 1.

Example 4

(24) As shown in FIG. 3, Example 4 provides a broadband polarization beam splitter/combiner based on gradient waveguide directional coupler. The broadband polarization beam splitter/combiner of the invention comprises a gradient waveguide directional coupler, a beam combining end 1, a curved waveguide 5, a transverse electric mode TE end 6 and a transverse magnetic mode TM end 7. The gradient waveguide directional coupler consists of a straight end gradient waveguide 2 and a serial end gradient waveguide 3. The width of the straight end gradient waveguide 2 is increased from 0.35 m to 0.6 m, the width of the serial end gradient waveguide 3 is tapered from 0.6 m to 0.35 m, and a gap 4 is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3. The beam combining end 1 is connected with one end of the straight end gradient waveguide 2, the other end of the straight end gradient waveguide 2 is connected with one end of the curved waveguide 5, the other end of the curved waveguide 5 is connected with the transverse electric mode TE end 6, and the serial end gradient waveguide 3 is connected with the transverse magnetic mode TM end 7.

(25) When the broadband polarization beam splitter/combiner is used as a beam splitter, a light is incident from the beam combining end 1, a light of TE mode exits from the transverse electric mode TE end 6, and a light of TM mode exits from the transverse magnetic mode TM end 7.

(26) When the broadband polarization beam splitter/combiner is used as a beam combiner, a light of TE mode is incident from the transverse electric mode TE end 6, a light of TM mode is incident from the transverse magnetic mode TM end 7, and a light resulting from combining the two polarized light exits from the beam combining end 1.

Example 5

(27) As shown in FIG. 2, Example 5 provides a broadband polarization beam splitter/combiner based on gradient waveguide directional coupler. The broadband polarization beam splitter/combiner of the invention comprises a gradient waveguide directional coupler, a beam combining end 1, a curved waveguide 5, a transverse electric mode TE end 6 and a transverse magnetic mode TM end 7. The gradient waveguide directional coupler consists of a straight end gradient waveguide 2 and a serial end gradient waveguide 3. The width of the straight end gradient waveguide 2 is tapered from 0.7 m to 0.4 m, the width of the serial end gradient waveguide 3 is increased from 0.4 m to 0.7 m, and a gap 4 is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3. The beam combining end 1 is connected with one end of the straight end gradient waveguide 2, the other end of the straight end gradient waveguide 2 is connected with one end of the curved waveguide 5, the other end of the curved waveguide 5 is connected with the transverse electric mode TE end 6, and the serial end gradient waveguide 3 is connected with the transverse magnetic mode TM end 7.

(28) When the broadband polarization beam splitter/combiner is used as a beam splitter, a light is incident from the beam combining end 1, a light of TE mode exits from the transverse electric mode TE end 6, and a light of TM mode exits from the transverse magnetic mode TM end 7.

(29) When the broadband polarization beam splitter/combiner is used as a beam combiner, a light of TE mode is incident from the transverse electric mode TE end 6, a light of TM mode is incident from the transverse magnetic mode TM end 7, and a light resulting from combining the two polarized light exits from the beam combining end 1.

Example 6

(30) As shown in FIG. 3, Example 6 provides a broadband polarization beam splitter/combiner based on gradient waveguide directional coupler. The broadband polarization beam splitter/combiner of the invention comprises a gradient waveguide directional coupler, a beam combining end 1, a curved waveguide 5, a transverse electric mode TE end 6 and a transverse magnetic mode TM end 7. The gradient waveguide directional coupler consists of a straight end gradient waveguide 2 and a serial end gradient waveguide 3. The width of the straight end gradient waveguide 2 is increased from 0.4 m to 0.7 m, the width of the serial end gradient waveguide 3 is tapered from 0.7 m to 0.4 m, and a gap 4 is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3. The beam combining end 1 is connected with one end of the straight end gradient waveguide 2, the other end of the straight end gradient waveguide 2 is connected with one end of the curved waveguide 5, the other end of the curved waveguide 5 is connected with the transverse electric mode TE end 6, and the serial end gradient waveguide 3 is connected with the transverse magnetic mode TM end 7.

(31) When the broadband polarization beam splitter/combiner is used as a beam splitter, a light is incident from the beam combining end 1, a light of TE mode exits from the transverse electric mode TE end 6, and a light of TM mode exits from the transverse magnetic mode TM end 7.

(32) When the broadband polarization beam splitter/combiner is used as a beam combiner, a light of TE mode is incident from the transverse electric mode TE end 6, a light of TM mode is incident from the transverse magnetic mode TM end 7, and a light resulting from combining the two polarized light exits from the beam combining end 1.

Example 7

(33) As shown in FIG. 2, Example 7 provides a broadband polarization beam splitter/combiner based on gradient waveguide directional coupler. The broadband polarization beam splitter/combiner of the invention comprises a gradient waveguide directional coupler, a beam combining end 1, a curved waveguide 5, a transverse electric mode TE end 6 and a transverse magnetic mode TM end 7. The gradient waveguide directional coupler consists of a straight end gradient waveguide 2 and a serial end gradient waveguide 3. The width of the straight end gradient waveguide 2 is tapered from 0.8 m to 0.4 m, the width of the serial end gradient waveguide 3 is increased from 0.4 m to 0.8 m, and a gap 4 is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3. The beam combining end 1 is connected with one end of the straight end gradient waveguide 2, the other end of the straight end gradient waveguide 2 is connected with one end of the curved waveguide 5, the other end of the curved waveguide 5 is connected with the transverse electric mode TE end 6, and the serial end gradient waveguide 3 is connected with the transverse magnetic mode TM end 7.

(34) When the broadband polarization beam splitter/combiner is used as a beam splitter, a light is incident from the beam combining end 1, a light of TE mode exits from the transverse electric mode TE end 6, and a light of TM mode exits from the transverse magnetic mode TM end 7.

(35) When the broadband polarization beam splitter/combiner is used as a beam combiner, a light of TE mode is incident from the transverse electric mode TE end 6, a light of TM mode is incident from the transverse magnetic mode TM end 7, and a light resulting from combining the two polarized light exits from the beam combining end 1.

Example 8

(36) As shown in FIG. 3, Example 8 provides a broadband polarization beam splitter/combiner based on gradient waveguide directional coupler. The broadband polarization beam splitter/combiner of the invention comprises a gradient waveguide directional coupler, a beam combining end 1, a curved waveguide 5, a transverse electric mode TE end 6 and a transverse magnetic mode TM end 7. The gradient waveguide directional coupler consists of a straight end gradient waveguide 2 and a serial end gradient waveguide 3. The width of the straight end gradient waveguide 2 is increased from 0.4 m to 0.8 m, the width of the serial end gradient waveguide 3 is tapered from 0.8 m to 0.4 m, and a gap 4 is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3. The beam combining end 1 is connected with one end of the straight end gradient waveguide 2, the other end of the straight end gradient waveguide 2 is connected with one end of the curved waveguide 5, the other end of the curved waveguide 5 is connected with the transverse electric mode TE end 6, and the serial end gradient waveguide 3 is connected with the transverse magnetic mode TM end 7.

(37) When the broadband polarization beam splitter/combiner is used as a beam splitter, a light is incident from the beam combining end 1, a light of TE mode exits from the transverse electric mode TE end 6, and a light of TM mode exits from the transverse magnetic mode TM end 7.

(38) When the broadband polarization beam splitter/combiner is used as a beam combiner, a light of TE mode is incident from the transverse electric mode TE end 6, a light of TM mode is incident from the transverse magnetic mode TM end 7, and a light resulting from combining the two polarized light exits from the beam combining end 1.

Example 9

(39) As shown in FIG. 2, Example 9 provides a broadband polarization beam splitter/combiner based on gradient waveguide directional coupler. The broadband polarization beam splitter/combiner of the invention comprises a gradient waveguide directional coupler, a beam combining end 1, a curved waveguide 5, a transverse electric mode TE end 6 and a transverse magnetic mode TM end 7. The gradient waveguide directional coupler consists of a straight end gradient waveguide 2 and a serial end gradient waveguide 3. The width of the straight end gradient waveguide 2 is tapered from 0.9 m to 0.45 m, the width of the serial end gradient waveguide 3 is increased from 0.45 m to 0.9 m, and a gap 4 is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3. The beam combining end 1 is connected with one end of the straight end gradient waveguide 2, the other end of the straight end gradient waveguide 2 is connected with one end of the curved waveguide 5, the other end of the curved waveguide 5 is connected with the transverse electric mode TE end 6, and the serial end gradient waveguide 3 is connected with the transverse magnetic mode TM end 7.

(40) When the broadband polarization beam splitter/combiner is used as a beam splitter, a light is incident from the beam combining end 1, a light of TE mode exits from the transverse electric mode TE end 6, and a light of TM mode exits from the transverse magnetic mode TM end 7.

(41) When the broadband polarization beam splitter/combiner is used as a beam combiner, a light of TE mode is incident from the transverse electric mode TE end 6, a light of TM mode is incident from the transverse magnetic mode TM end 7, and a light resulting from combining the two polarized light exits from the beam combining end 1.

Example 10

(42) As shown in FIG. 3, Example 10 provides a broadband polarization beam splitter/combiner based on gradient waveguide directional coupler. The broadband polarization beam splitter/combiner of the invention comprises a gradient waveguide directional coupler, a beam combining end 1, a curved waveguide 5, a transverse electric mode TE end 6 and a transverse magnetic mode TM end 7. The gradient waveguide directional coupler consists of a straight end gradient waveguide 2 and a serial end gradient waveguide 3. The width of the straight end gradient waveguide 2 is increased from 0.45 m to 0.9 m, the width of the serial end gradient waveguide 3 is tapered from 0.9 m to 0.45 m, and a gap 4 is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3. The beam combining end 1 is connected with one end of the straight end gradient waveguide 2, the other end of the straight end gradient waveguide 2 is connected with one end of the curved waveguide 5, the other end of the curved waveguide 5 is connected with the transverse electric mode TE end 6, and the serial end gradient waveguide 3 is connected with the transverse magnetic mode TM end 7.

(43) When the broadband polarization beam splitter/combiner is used as a beam splitter, a light is incident from the beam combining end 1, a light of TE mode exits from the transverse electric mode TE end 6, and a light of TM mode exits from the transverse magnetic mode TM end 7.

(44) When the broadband polarization beam splitter/combiner is used as a beam combiner, a light of TE mode is incident from the transverse electric mode TE end 6, a light of TM mode is incident from the transverse magnetic mode TM end 7, and a light resulting from combining the two polarized light exits from the beam combining end 1.

Example 11

(45) As shown in FIG. 2, Example 11 provides a broadband polarization beam splitter/combiner based on gradient waveguide directional coupler. The broadband polarization beam splitter/combiner of the invention comprises a gradient waveguide directional coupler, a beam combining end 1, a curved waveguide 5, a transverse electric mode TE end 6 and a transverse magnetic mode TM end 7. The gradient waveguide directional coupler consists of a straight end gradient waveguide 2 and a serial end gradient waveguide 3. The width of the straight end gradient waveguide 2 is tapered from 1 m to 0.45 m, the width of the serial end gradient waveguide 3 is increased from 0.45 m to 1 m, and a gap 4 is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3. The beam combining end 1 is connected with one end of the straight end gradient waveguide 2, the other end of the straight end gradient waveguide 2 is connected with one end of the curved waveguide 5, the other end of the curved waveguide 5 is connected with the transverse electric mode TE end 6, and the serial end gradient waveguide 3 is connected with the transverse magnetic mode TM end 7.

(46) When the broadband polarization beam splitter/combiner is used as a beam splitter, a light is incident from the beam combining end 1, a light of TE mode exits from the transverse electric mode TE end 6, and a light of TM mode exits from the transverse magnetic mode TM end 7.

(47) When the broadband polarization beam splitter/combiner is used as a beam combiner, a light of TE mode is incident from the transverse electric mode TE end 6, a light of TM mode is incident from the transverse magnetic mode TM end 7, and a light resulting from combining the two polarized light exits from the beam combining end 1.

Example 12

(48) As shown in FIG. 3, Example 12 provides a broadband polarization beam splitter/combiner based on gradient waveguide directional coupler. The broadband polarization beam splitter/combiner of the invention comprises a gradient waveguide directional coupler, a beam combining end 1, a curved waveguide 5, a transverse electric mode TE end 6 and a transverse magnetic mode TM end 7. The gradient waveguide directional coupler consists of a straight end gradient waveguide 2 and a serial end gradient waveguide 3. The width of the straight end gradient waveguide 2 is increased from 0.45 m to 1 m, the width of the serial end gradient waveguide 3 is tapered from 1 m to 0.45 m, and a gap 4 is provided between the straight end gradient waveguide 2 and the serial end gradient waveguide 3. The beam combining end 1 is connected with one end of the straight end gradient waveguide 2, the other end of the straight end gradient waveguide 2 is connected with one end of the curved waveguide 5, the other end of the curved waveguide 5 is connected with the transverse electric mode TE end 6, and the serial end gradient waveguide 3 is connected with the transverse magnetic mode TM end 7.

(49) When the broadband polarization beam splitter/combiner is used as a beam splitter, a light is incident from the beam combining end 1, a light of TE mode exits from the transverse electric mode TE end 6, and a light of TM mode exits from the transverse magnetic mode TM end 7.

(50) When the broadband polarization beam splitter/combiner is used as a beam combiner, a light of TE mode is incident from the transverse electric mode TE end 6, a light of TM mode is incident from the transverse magnetic mode TM end 7, and a light resulting from combining the two polarized light exits from the beam combining end 1.