1. A waveguide-to-fiber three-dimensional polymer horizontal lens coupler, comprising:

the polymer coupling waveguide structure is used for converting light beams in the existing waveguide on the integrated photonic chip from a waveguide optical mode into a polymer optical mode and gradually coupling the polymer optical mode into the coupler;

a polymer three-dimensional waveguide for raising an optical mode proximate to a substrate by a height equivalent to a height of a polymer lens optical mode converter and into the polymer lens optical mode converter;

a polymer lens optical mode converter for magnifying a current optical mode volume;

wherein the bottom surfaces of the polymer coupled waveguide structure and the polymer lens optical mode converter are in contact with the surface of the substrate.

2. A waveguide-to-fiber three dimensional polymer horizontal lens coupler according to claim 1, wherein the polymer lens optical mode converter is a three dimensional lens structure consisting of a tapered beam expanding structure and a conical curved surface.

3. A waveguide-to-fiber three dimensional polymer horizontal lens coupler according to claim 2, wherein the tapered beam expanding structure has a length of no more than 30 microns and gradually increases in size, expanding in cross-section from 3.5 microns by 3.5 microns to no more than 30 microns by 30 microns; the curvature radius of the conical curved surface is larger than 3 micrometers and smaller than 20 micrometers, the absolute value of the conical coefficient is not larger than 3, and the length is not larger than 50 micrometers.

4. A waveguide-to-fiber three dimensional polymer horizontal lens coupler according to claim 3, wherein the combined material of the polymer coupled waveguide structure, the polymer three dimensional waveguide, the polymer lens optical mode converter comprises one or more of SU8 photoresist, IP-L photoresist, IP-D photoresist, IP-S photoresist, AZ photoresist.

5. A waveguide-to-fiber three-dimensional polymer horizontal lens coupler according to claim 4, wherein said polymer coupled waveguide structure has a length of less than 10 microns when interfaced with SU8 waveguide, a length of less than 300 microns when interfaced with silicon waveguide, and a length of less than 450 microns when interfaced with lithium niobate waveguide.

6. A waveguide-to-fiber three-dimensional polymer horizontal lens coupler according to claim 5, wherein the polymer three-dimensional waveguide is a curved waveguide symmetric mirror Euler curved structure, the turning angle of the symmetric mirror Euler curved structure is less than or equal to 10 degrees, the minimum turning radius is greater than or equal to 200 microns, the total height is less than or equal to 10 microns, and the total length is less than or equal to 300 microns.

7. A waveguide-to-fiber three dimensional polymer horizontal lens coupler according to claim 6, wherein the single Euler bend minimum turning radius point is forward of the structure center.

8. The waveguide-to-fiber three-dimensional polymer horizontal lens coupler of claim 7, wherein the waveguide-to-fiber three-dimensional polymer horizontal lens coupler is positioned on the waveguide structure on the integrated optical circuit by a three-dimensional laser direct writing technology.

Background

With the rapid development of communication network technology, the integrated photonic chip based on the silicon-based photonic device will replace the traditional network transceiver device and become the leading technology of optical communication network gradually due to its superior performances such as low cost, low loss, high integration level, etc. Meanwhile, optical fibers have become the most important optical information transmission medium due to their advantages of large bandwidth, low loss, and the like. However, since the waveguide structure used in the integrated photonic chip is usually a high refractive index material, and the dielectric material used in the optical fiber is a low refractive index material, there is a problem of optical mode mismatch between them, which results in large loss of light in the process of propagating from the integrated optical circuit to the optical fiber.

The existing coupling schemes are mainly divided into horizontal coupling and vertical coupling. The vertical coupling comprises a grating coupler, a three-dimensional vertical coupler and the like, and the applicable scene is mainly limited to wafer testing; the horizontal coupling comprises a silicon dioxide planar waveguide, an SU8 horizontal waveguide and the like, has wider application range and is particularly suitable for chip coupling packaging. The silicon dioxide planar waveguide and the SU8 horizontal waveguide both convert the optical waveguide mode of the high refractive index material to the low refractive index material in the horizontal direction and exit from the end face, but due to the limitation of planar process, the converted optical mode still has a small volume, and can be coupled with a lensed fiber only, or an off-chip coupling element needs to be added, and the coupling efficiency is low, and the requirements on coupling space and cost are high.

Disclosure of Invention

In view of the above, the present invention provides a waveguide-to-optical fiber three-dimensional polymer horizontal lens coupler, so as to solve the technical problems of low coupling efficiency and high coupling and packaging requirements of the conventional waveguide-to-optical fiber horizontal coupler.

The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed embodiments. This summary is not an extensive overview and is intended to neither identify key/critical elements nor delineate the scope of such embodiments. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

The invention adopts the following technical scheme:

in some alternative embodiments, there is provided a waveguide-to-fiber three-dimensional polymer horizontal lens coupler comprising: the polymer coupling waveguide structure is used for converting light beams in the existing waveguide on the integrated photonic chip from a waveguide optical mode into a polymer optical mode and gradually coupling the polymer optical mode into the coupler; a polymer three-dimensional waveguide for raising an optical mode proximate to a substrate by a height equivalent to a height of a polymer lens optical mode converter and into the polymer lens optical mode converter; a polymer lens optical mode converter for magnifying a current optical mode volume; wherein the bottom surfaces of the polymer coupled waveguide structure and the polymer lens optical mode converter are in contact with the surface of the substrate.

Further, the polymer lens optical mode converter is a three-dimensional lens structure and is composed of a conical beam expanding structure and a conical curved surface.

Further, the length of the conical expanded beam structure is not more than 30 micrometers, the conical expanded beam structure becomes gradually larger, and the cross section of the conical expanded beam structure is expanded from 3.5 micrometers to not more than 30 micrometers to 30 micrometers; the curvature radius of the conical curved surface is larger than 3 micrometers and smaller than 20 micrometers, the absolute value of the conical coefficient is not larger than 3, and the length is not larger than 50 micrometers.

Further, the combined material of the polymer coupling waveguide structure, the polymer three-dimensional waveguide and the polymer lens optical mode converter comprises one or more of SU8 photoresist, IP-L photoresist, IP-D photoresist, IP-S photoresist and AZ photoresist.

Further, the polymer coupled waveguide structure has a length of less than 10 microns when interfaced with the SU8 waveguide, a length of less than 300 microns when interfaced with the silicon waveguide, and a length of less than 450 microns when interfaced with the lithium niobate waveguide.

Furthermore, the polymer three-dimensional waveguide is a bent waveguide symmetrical mirror image Euler bending structure, the turning angle of the symmetrical mirror image Euler bending structure is less than or equal to 10 degrees, the minimum turning radius is more than or equal to 200 microns, the total height is less than or equal to 10 microns, and the total length is less than or equal to 300 microns.

Further, the single Euler bend minimum turn radius point is forward of the structure center.

Further, the waveguide-to-fiber three-dimensional polymer horizontal lens coupler is positioned on a waveguide structure on the integrated optical circuit through a three-dimensional laser direct writing technology.

The invention has the following beneficial effects: the invention enables the optical mode to be coupled with the single-mode fiber in low loss and large wavelength band width, and has the characteristics of coupling loss less than 2dB, working wavelength band width more than 100nm and low polarization correlation on the premise of high compatibility with CMOS (complementary metal oxide semiconductor) process, and the structure of the invention is more stable.

Drawings

FIG. 1 is a schematic diagram of a waveguide-to-fiber three-dimensional polymer horizontal lens coupler according to the present invention.

FIG. 2 is a side view of a waveguide-to-fiber three-dimensional polymer horizontal lens coupler of the present invention.

Detailed Description

The following description and the drawings sufficiently illustrate specific embodiments of the invention to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. The examples merely typify possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in or substituted for those of others.

As shown in fig. 1-2, in some illustrative embodiments, there is provided a waveguide-to-fiber three-dimensional polymer horizontal lens coupler comprising: a polymer coupled waveguide structure 4, a polymer three-dimensional waveguide 3, and a polymer lens optical mode converter 2. The polymer coupling waveguide structure 4, the polymer three-dimensional waveguide 3 and the polymer lens optical mode converter 2 are sequentially connected.

And a polymer coupling waveguide structure 4 for converting the light beam in the existing waveguide on the integrated photonic chip from a waveguide optical mode to a polymer optical mode and gradually coupling into the coupler. The polymer coupled waveguide structure 4, when illustrated as a silicon waveguide to single mode fiber coupling, functions to gradually couple the optical mode in the silicon waveguide into the optical mode of the polymer waveguide and finally into the polymer three dimensional waveguide 3. The polymer coupled waveguide structure 4 is laid on a horizontal plane, and can be in butt-joint epitaxy with existing waveguides on an integrated optical path, such as a silicon waveguide, an SU8 waveguide, a lithium niobate waveguide and the like, so that a waveguide optical mode enters a coupler.

And the polymer three-dimensional waveguide 3 is used for lifting the optical mode close to the substrate to the height equal to that of the polymer lens optical mode converter 2 through the bent waveguide structure, so that the optical mode enters the polymer lens optical mode converter 2 and is conveniently connected with a polymer lens.

The polymer lens optical mode converter 2 is used for amplifying the volume of the current optical mode, namely, the existing optical mode volume is converted into the size which can be matched with the optical fiber 1, the size of a mode field of the optical mode in the polymer lens optical mode converter 2 is increased due to the fact that the size of a waveguide is gradually increased, and the optical mode is finally matched with the optical mode of the optical fiber 1, and the purpose of efficient coupling is achieved.

The optical fiber 1 includes, but is not limited to, a single mode fiber, a few-mode fiber, and a tapered fiber.

The bottom surfaces of the polymer coupling waveguide structure 4 and the polymer lens optical mode converter 2 are both in contact with the surface of the substrate, so that the three-dimensional structure is stable, and the final coupling efficiency is close to 1dB, namely 80%. Wherein the substrate material includes but is not limited to silicon, silicon dioxide, silicon nitride. Since the polymer three-dimensional waveguide 3 is a curved waveguide structure, it does not contact with the substrate surface.

The polymer lens optical mode converter 2 is a three-dimensional lens structure and is composed of a conical beam expanding structure 201 and a conical curved surface 202. In order to realize high-efficiency coupling of the waveguide and the optical fiber, the length of the tapered beam expanding structure is not more than 30 micrometers and gradually becomes larger, and the cross section is expanded from 3.5 micrometers multiplied by 3.5 micrometers to not more than 30 micrometers multiplied by 30 micrometers; the curvature radius of the conical curved surface is larger than 3 micrometers and smaller than 20 micrometers, the absolute value of the conical coefficient is not larger than 3, and the length is not larger than 50 micrometers. The structure aims to converge the optical fiber to a certain size through the refraction effect of the curved surface, and realize the high overlapping with the mode spot of the single-mode optical fiber.

When the coupling from the silicon waveguide to the single-mode fiber is taken as an example for explanation, the length of the tapered beam expanding structure is 15 micrometers, the cross section is expanded from 3.5 micrometers multiplied by 3.5 micrometers to 16 micrometers multiplied by 16 micrometers, the curvature radius of the conical surface is 7 micrometers, the conical coefficient is-0.5, and the length of the coupler is equal to 20 micrometers.

The polymer coupling waveguide structure 4, the polymer three-dimensional waveguide 3 and the polymer lens optical mode converter 2 are made of one or more of SU8 photoresist, IP-L photoresist, IP-D photoresist, IP-S photoresist and AZ photoresist. When the coupling of a silicon waveguide to a single-mode optical fiber is taken as an example for illustration, the combined material of the polymer coupling waveguide structure 4, the polymer three-dimensional waveguide 3 and the polymer lens optical mode converter 2 is selected to be an IP-L photoresist.

The polymer material used in the invention includes but is not limited to a photoresist which has a communication waveband of 1000 nm-1700 nm and is transparent, namely a photoresist with light absorptivity lower than 1%.

The polymer coupled waveguide structure 4 has a length of less than 10 microns when interfaced with SU8 waveguides, a length of less than 300 microns when interfaced with silicon waveguides, and a length of less than 450 microns when interfaced with lithium niobate waveguides.

The polymer three-dimensional waveguide 3 is a curved waveguide symmetrical mirror Euler curved structure, the turning angle of the curved waveguide symmetrical mirror Euler curved structure is less than or equal to 10 degrees, the minimum turning radius is more than or equal to 200 microns, the total height is less than or equal to 10 microns, and the total length is less than or equal to 300 microns. When a silicon waveguide is taken as an example for coupling to a single-mode fiber, the polymer three-dimensional waveguide 3 has a turning angle of 6.5 °, a minimum turning radius of 200 μm, a total height of 6 μm, and a total length of 200 μm.

The single euler bend minimum turning radius point is forward of the structure center.

The waveguide-to-optical fiber three-dimensional polymer horizontal lens coupler is positioned on a waveguide structure on an integrated optical circuit through a three-dimensional laser direct writing technology. The specific manufacturing method comprises the following steps:

s1: a silicon-based optical structure and an SU8 waveguide structure are manufactured on a substrate of a silicon-on-insulator thin film by using a photoetching technology, or a lithium niobate-based optical structure and an SU8 waveguide structure are manufactured on a substrate of a lithium niobate thin film on an insulator by using the photoetching technology;

s2: dropping a photoresist on the optical structure obtained in step S1;

s3: placing the sample obtained in the step S2 into a three-dimensional laser direct writing machine, and positioning a waveguide structure to be butted by using an optical imaging system;

s4: photoetching a three-dimensional coupler in the sample obtained in step S3;

s5: and (5) putting the sample obtained in the step S4 into a developing solution for developing and removing the redundant photoresist to obtain a final structure.

The invention provides a waveguide-to-optical fiber three-dimensional polymer horizontal lens coupler, which can enable a waveguide optical mode in an integrated optical circuit to be effectively and horizontally coupled into a single-mode optical fiber, and compared with the existing coupling schemes such as a grating coupler and the like, the coupling loss is less than 2dB, the working wavelength bandwidth is more than 100nm on the premise of high compatibility with a CMOS (complementary metal oxide semiconductor) process, and the waveguide-to-optical fiber three-dimensional polymer horizontal lens coupler has the characteristic of low polarization correlation.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.