CN103901559B - Optical coupling device - Google Patents

Abstract

An optical coupling device comprises a substrate, a flat optical waveguide formed on the substrate and a medium grating film formed on the flat optical waveguide. The flat optical waveguide is used for butting with a laser light source so as to receive scattered laser beams sent by the laser light source. The medium grating film comprises a first medium grating and a second medium grating which is in interval arrangement with the first medium grating. The first medium grating is located at the emitting light path of the laser light source and is used for converging the scattered laser beams into parallel laser beams. The second medium grating is located at the emitting light path of the first medium grating and is used for converging the parallel laser beams and coupling the converged parallel laser beams to an optical element. Therefore, the medium grating film and the flat optical waveguide form a loaded-type optical waveguide for converging the laser beams emitted by the laser light source, thereby improving light utilization rate.

Description

Optical coupling device

technical field

The invention relates to an integrated optical device, in particular to an optical coupling device.

Background technique

In integrated optics, laser light with better directionality is generally used as the light source. However, the beam emitted by the laser still has a certain divergence angle. If the light source is directly connected to the optical element, the divergent light in the beam will not be able to enter the optical element, and the light utilization rate will be low. . Therefore, how to couple the light source to the optical element so that the divergent light beam converges into the optical element to improve light utilization is an important issue.

Contents of the invention

In view of this, it is necessary to provide an optical coupling device capable of improving light utilization.

An optical coupling device includes a substrate, a flat optical waveguide formed on the substrate, and a dielectric grating film formed on the flat optical waveguide. The slab optical waveguide is used for docking with a laser light source to receive the divergent laser beam emitted by the laser light source, and the dielectric grating film includes a first dielectric grating and a second dielectric grating spaced apart from the first dielectric grating. Media grating. The first dielectric grating is located on the exit light path of the laser light source and is used to converge the diverging laser beams into parallel laser beams. The second dielectric grating is located on the outgoing light path of the first dielectric grating and is used for converging the parallel laser beams and coupling the collimated parallel beams to an optical element.

According to the theory of integrated optics, for example, the first dielectric grating and the second dielectric grating are set as chirped gratings, and further according to the relative position between the laser light source and the optical element, the first dielectric grating and the second dielectric grating are set reasonably. The structure of the second dielectric grating is such that the laser beam emitted by the laser light source is coupled to the optical element.

Description of drawings

FIG. 1 is a schematic structural diagram of an optical coupling device provided by the present invention.

FIG. 2 is a schematic cross-sectional view of the optical coupling device of FIG. 1 along the line II-II.

FIG. 3 is a schematic plan view of the first dielectric grating in FIG. 1 .

Explanation of main component symbols

Optocoupler 10

base 110

top 111

side 112

Planar optical waveguide 120

Dielectric Grating Film 130

First dielectric grating 131

First rectangular rib 1311

Second rectangular rib 1312

First axis of symmetry O

Second dielectric grating 132

Third rectangular rib 1321

Fourth rectangular rib 1322

Second axis of symmetry A

Rectangular groove 133

Laser light source 20

laser beam 21

Optics 30

The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings.

detailed description

The embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

1 and 2, the optical coupling device 10 provided by the embodiment of the present invention includes a substrate 110, a slab optical waveguide 120 formed on the substrate 110, and a dielectric grating formed on the slab optical waveguide 120. Film 130.

The base 110 is substantially rectangular and includes a top surface 111 and a side surface 112 vertically connected to the top surface 111 . Considering that lithium niobate diffused metal titanium (single substance) can form a loaded optical waveguide with graded refractive index, the material of the substrate 110 is lithium niobate crystal. In other embodiments, the substrate 110 may also be made of materials such as ceramics or plastics, and the planar optical waveguide 120 is formed by forming semiconductor materials such as silicon dioxide, silicon, and other materials on the ceramic or plastic substrate 110 through a semiconductor process. .

The planar optical waveguide 120 is formed by coating the top surface 111 with titanium metal and then diffusing the titanium metal into the base 110 at high temperature. In this embodiment, corresponding to the shape of the substrate 110, the flat optical waveguide 120 is rectangular, the top surface 111 is the top surface of the flat optical waveguide 120, and the side surface 112 is the flat optical waveguide 120. side of the waveguide 120 . The flat optical waveguide 120 is used to connect with a laser light source 20 to receive the laser beam 21 emitted by the laser light source 20 .

The dielectric grating film 130 is formed by sputtering, evaporating or coating a layer of high refractive index material film on the top surface 111, and the high refractive index material can be silicon dioxide, silicon dioxide doped with boron or mixtures of phosphorus or organic compounds. In this embodiment, the dielectric grating film 130 is an organic compound coated on the top surface 111, and is formed by etching the dielectric grating film 130 of the organic compound using a yellow photolithography (yellow photolithography) process. A first dielectric grating 131 and a second dielectric grating 132 spaced apart from the first dielectric grating.

In this implementation manner, the first dielectric grating 131 is a chirped grating. The first dielectric grating 131 includes a first rectangular convex strip 1311 in the middle and a plurality of second rectangular convex strips 1312 symmetrically distributed on both sides of the first rectangular convex strip 1311. The first rectangular convex strip 1311 And the sum of the number of the second rectangular convex strips 1312 is an odd number, the first rectangular convex strips 1311 and a plurality of second rectangular convex strips 1312 are arranged in parallel with each other, and the width of the first rectangular convex strips 1311 is greater than each The width of each second rectangular convex strip 1312, and from the first rectangular convex strip 1311 to the direction away from the first rectangular convex strip 1311, the width of the plurality of second rectangular convex strips 1312 becomes smaller and smaller, And the gaps between the second rectangular convex strip 1312 and the first rectangular convex strip 1311 and two adjacent second rectangular convex strips 1312 are getting smaller and smaller.

Please refer to FIG. 3 , in this embodiment, the first rectangular convex strip 1311 includes a rectangular upper surface opposite to the planar optical waveguide 120 . The rectangular upper surface of the first rectangular protrusion 1311 includes two long sides and two wide sides. Taking the line connecting the central points of the two broad sides of the rectangular upper surface of the first rectangular convex strip 1311 as the first axis of symmetry O, the extension of one of the broad sides of the rectangular upper surface of the first dielectric grating 131 The direction is the x-axis, the intersection point of the first symmetry axis O on the x-axis is the origin, the direction along the first symmetry axis O to the direction away from the first symmetry axis O is the positive direction of the x-axis, and the laser The phase difference between the beam 21 at x and the origin is the y axis, and according to the planar optical waveguide wave theory: Where x>0, then the nth boundary x _n of the first dielectric grating 131 satisfies the following conditions: Wherein, n is a positive integer, y _n =nπ, and a and k are constants related to the focal length of the diffractive optical waveguide lens. In this way, it can be deduced that: In the case of x<0, that is, the boundary of the first dielectric grating 1311 on the left side of the first symmetry axis O can be obtained through symmetry.

Please refer to FIG. 1 again, the structure of the second dielectric grating 132 is exactly the same as that of the first dielectric grating 131 , it is also a chirped grating and is symmetrical about a second symmetry axis A. The second dielectric grating 132 includes a third rectangular convex strip 1321 in the middle and a plurality of fourth rectangular convex strips 1322 symmetrically distributed on both sides of the third rectangular convex strip 1321. The third rectangular convex strip 1321 And the sum of the number of the fourth rectangular convex strips 1322 is an odd number, the third rectangular convex strips 1321 and a plurality of fourth rectangular convex strips 1322 are arranged in parallel with each other, and the width of the third rectangular convex strips 1321 is greater than each The width of each fourth rectangular convex strip 1322, and from the third rectangular convex strip 1321 to the direction away from the third rectangular convex strip 1321, the width of the plurality of fourth rectangular convex strips 1322 becomes smaller and smaller, And the gaps between the fourth rectangular convex strip 1322 and the third rectangular convex strip 1321 and two adjacent fourth rectangular convex strips 1322 are getting smaller and smaller.

A rectangular groove 133 is defined between the first dielectric grating 131 and the second dielectric grating 132 . The width of the rectangular groove 133 is the distance between the first dielectric grating 131 and the second dielectric grating 132 . The first axis of symmetry O is aligned with the second axis of symmetry A. Each second rectangular protruding strip 1312 corresponds to a fourth rectangular protruding strip 1322 .

The laser light source 20 adopts a distributed feedback laser (distributed feedback laser, DFB), which belongs to a side-emitting semiconductor laser, and the light-emitting side can be directly welded to the side 112 by a die bond method, and the The central axis of the laser light source 20 is incident on the first axis of symmetry O. Certainly, the laser light source 20 may also adopt other types of laser light sources and be arranged in other ways. The first dielectric grating 131 is located in the outgoing light path of the laser light source. The second dielectric grating 132 is located in the outgoing optical path of the first dielectric grating 131 .

The optical coupling device 10 further includes an optical element 30 arranged on the light-emitting optical path of the second dielectric grating 132, the central axis of the optical element 30 is aligned with the center of the third rectangular convex strip 1321 axis, so that the first rectangular convex strip 1311, the second rectangular convex strip 1312, the third rectangular convex strip 1321 and the fourth rectangular convex strip 1322 are all parallel to the laser light source 20 and the optical The connecting line of the central axis of the element 30 is set. The optical element 30 may be a strip optical waveguide, an optical fiber or a splitter. In this embodiment, the optical element 30 is a strip optical waveguide.

In use, the laser light source 20 emits divergent laser beams and projects the divergent laser beams to the first dielectric grating 131 . The first dielectric grating 131 converges the diverging laser beams into parallel laser beams. The second dielectric grating 132 condenses the parallel laser beams and couples the condensed parallel beams to the optical element 30 .

According to the theory of integrated optics, according to the relative position between the laser light source 20 and the optical element 30, the structure of the first dielectric grating 131 and the second dielectric grating 132, and the structure of the first dielectric grating 131 relative to the laser light source 20 are reasonably set. position and the position of the second dielectric grating 132 relative to the optical element 30 , so that the laser beam emitted by the laser light source 20 is coupled to the optical element 30 .

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. In addition, those skilled in the art can also make other changes within the spirit of the present invention. Of course, these changes made according to the spirit of the present invention should all be included within the scope of protection claimed by the present invention.

Claims (9)

1. An optical coupling device comprising a substrate, a flat optical waveguide formed on the substrate and a dielectric grating film formed on the flat optical waveguide; the flat optical waveguide is used to be used with a laser light source docking to receive the divergent laser beam emitted by the laser light source, the dielectric grating film includes a first dielectric grating and a second dielectric grating spaced apart from the first dielectric grating; the first dielectric grating is located at the The outgoing optical path of the laser light source is used to converge the divergent laser beams into parallel laser beams; the second dielectric grating is located on the outgoing optical path of the first dielectric grating and is used to converge the parallel laser beams and The converged parallel light beams are coupled to an optical element. 2. The optical coupling device as claimed in claim 1, wherein the first dielectric grating is a chirped grating, and the first dielectric grating includes a first rectangular ridge located in the middle and a plurality of symmetrically distributed For the second rectangular convex strip on both sides of the first rectangular convex strip, the sum of the number of the first rectangular convex strip and the second rectangular convex strip is an odd number, and the first rectangular convex strip and the plurality of second rectangular convex strips The two rectangular convex strips are rectangular and arranged parallel to each other, the width of the first rectangular convex strip is greater than the width of each second rectangular convex strip, and from the first rectangular convex strip to the distance away from the first rectangular convex strip direction, the widths of the plurality of second rectangular ridges are getting smaller and smaller, and the gaps between the second rectangular ridges and the first rectangular ridges and two adjacent second rectangular ridges are also getting smaller and smaller. smaller. 3. The optical coupling device according to claim 2, wherein the first rectangular convex strip comprises a rectangular upper surface opposite to the planar optical waveguide, and the rectangular upper surface comprises two long sides and Two broad sides, taking the line connecting the center points of the two broad sides of the upper surface of the rectangle as the first axis of symmetry, and taking the extension direction of one of the broad sides of the upper surface of the rectangle as the x-axis, the first The intersection point of the symmetry axis and the x-axis is the origin, the direction along the first symmetry axis to the direction away from the first symmetry axis is the positive direction of the x-axis, and the phase difference between the laser beam at the x-axis and the origin is The y-axis can be obtained according to the wave theory of flat optical waveguide: Where x>0, then the nth boundary x _n of the first dielectric grating satisfies the following conditions: Wherein, n is a positive integer, y _n =nπ, and a and k are constants. 4. The optical coupling device according to claim 3, wherein the structure of the second dielectric grating is the same as that of the first dielectric grating and is symmetrical about a second symmetry axis, and the second dielectric grating includes a The third rectangular ridge located in the middle and a plurality of fourth rectangular ridges symmetrically distributed on both sides of the third rectangular ridge, the second axis of symmetry is aligned with the first axis of symmetry. 5. The optical coupling device according to claim 4, wherein the first rectangular convex strip, the second rectangular convex strip, the third rectangular convex strip and the fourth rectangular convex strip are parallel It is arranged on the line connecting the central axis of the laser light source and the optical element. 6. The optical coupling device according to claim 1, wherein a rectangular groove is opened between the first dielectric grating and the second dielectric grating. 7. The optical coupling device according to claim 1, wherein the material of the substrate is lithium niobate crystal. 8. The optical coupling device according to claim 7, wherein the base is rectangular and includes a top surface and a side perpendicularly connected to the top surface, and the planar optical waveguide passes through to the top surface The surface is plated with metal titanium and then diffused into the substrate at high temperature to form the flat optical waveguide. The top surface is the top surface of the flat optical waveguide, and the side surfaces are the flat optical waveguide side. 9. The optical coupling device according to claim 8, wherein the dielectric grating film is coated with a layer of high-refractive-index material film from the top surface of the flat optical waveguide and etched by a yellow photolithography process. The first dielectric grating and the second dielectric grating are formed by using the high refractive index material film.