CN117950111A - Coupler, photonic integrated circuit and atomic molecular photophysical system - Google Patents

Coupler, photonic integrated circuit and atomic molecular photophysical system Download PDF

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Publication number
CN117950111A
CN117950111A CN202211352008.5A CN202211352008A CN117950111A CN 117950111 A CN117950111 A CN 117950111A CN 202211352008 A CN202211352008 A CN 202211352008A CN 117950111 A CN117950111 A CN 117950111A
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material layer
dimension
axis
light beam
coupler
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杨超
竺士炀
杨江陵
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Abstract

The application provides a coupler, a photon integrated circuit and an atomic molecular photophysical system, and relates to the technical field of photoelectrons. The coupler includes: a first focusing structure and a cladding layer disposed on the substrate; a first material layer extending along the light transmission direction, the first material layer being wrapped by a cladding layer, a first end of the first material layer facing the first focusing structure; the first material layer includes a first portion and a second portion along a light transmission direction from the first end; a first focusing structure for focusing a first light beam received from an optical fiber coupled to the coupler and outputting a second light beam; a first portion of the first material layer for changing a spot of the second light beam and outputting a third light beam; a second portion of the first material layer for transmitting a third light beam.

Description

Coupler, photonic integrated circuit and atomic molecular photophysical system
Technical Field
The application relates to the technical field of photoelectrons, in particular to a coupler, a photon integrated circuit and an atomic molecular photophysical system.
Background
The photonic integrated circuit (photonics integrated circuit, PIC) provides advantages for electro-optical integration, wherein the photonic integrated circuit PIC is provided with optical devices and electronic components, and is used for receiving the light beam transmitted by the optical fiber coupled with the photonic integrated circuit PIC, and processing the light beam to realize the functions of the photonic integrated circuit PIC.
In order to enable the light beam transmitted in the optical fiber to be coupled into the photonic integrated circuit PIC with higher coupling efficiency, a coupler is often further arranged in the photonic integrated circuit PIC, the coupler is used for coupling the photonic integrated circuit PIC and the optical fiber, and the coupler can enable the size of a mode spot of the light beam transmitted in the optical fiber to be suitable for being transmitted in the photonic integrated circuit PIC, so that the light beam transmitted in the optical fiber is coupled into the photonic integrated circuit PIC with higher coupling efficiency.
However, as the wavelength of the light beam transmitted in the optical fiber is continuously reduced, the coupling efficiency of the existing coupler is significantly reduced.
Disclosure of Invention
The application provides a coupler, a photon integrated circuit and an atomic molecular photophysical system, wherein the coupling efficiency of the coupler is higher than that of the existing coupler.
In a first aspect, there is provided a coupler comprising: a first focusing structure and a cladding layer disposed on the substrate; a first material layer extending along the light transmission direction, the first material layer being wrapped by a cladding layer, a first end of the first material layer facing the first focusing structure; the first material layer includes a first portion and a second portion along a light transmission direction from the first end; a first focusing structure for focusing a first light beam received from an optical fiber coupled to the coupler and outputting a second light beam; a first portion of the first material layer for changing a spot of the second light beam and outputting a third light beam; a second portion of the first material layer for transmitting a third light beam. In the coupler, the coupler comprises a first focusing structure and a cladding layer arranged on a substrate, wherein a first material layer extending along the light transmission direction is wrapped in the cladding layer, a first end of the first material layer faces the first focusing structure, and the first material layer comprises a first part and a second part along the light transmission direction from the first end, so that the light transmission path of a light beam in the coupler is as follows: first focusing structure-first portion of first material layer-second portion of first material layer. When the coupler is coupled with the optical fiber, the optical fiber may transmit a first light beam to the coupler, wherein the first focusing structure first receives the first light beam, the first focusing structure focuses energy of the first light beam, generates a second light beam, and outputs the second light beam to a first portion of the first material layer, the first portion of the first material layer is used to change a spot of the second light beam, generate a third light beam, and output the third light beam. For example, the original first beam has a spot size that matches the core of the optical fiber, the second beam is only more energy intensive than the first beam, and thus it can be considered that the spot size of the second beam also matches the core of the optical fiber, and the first portion of the first material layer changes the spot of the second beam and then outputs a third beam, the spot size of which matches the second portion of the first material layer, which in turn transmits the third beam to another place. According to the coupler, due to the arrangement of the first focusing structure, energy of the first light beam transmitted to the coupler by the optical fiber is focused through the first focusing structure and then transmitted to the first material layer, so that the energy proportion of the first light beam received in the first material layer is improved, and the coupling efficiency of the coupler is further improved.
Optionally, the focal length of the first focusing structure is less than or equal to a first predetermined value, where the first predetermined value is F, f= (pi×ω1×ω2)/λ; where ω1 is the beam waist radius of the first beam, ω2 is the beam waist radius of the third beam, and λ is the wavelength of the first beam. In this alternative manner, when the focal length of the first focusing structure is smaller than or equal to the first predetermined value, the coupler can achieve short focal length focusing of the first light beam received from the optical fiber, so that the distance between the first material layer and the focusing structure can be set to be relatively short, and the structure of the coupler is more compact.
Optionally, the coupler further comprises: a second material layer extending in the light transmission direction; the second material layer is wrapped by the cladding layer and is arranged on one side of the first material layer away from the substrate; the second material layer includes a first portion and a second portion along a light transmission direction from the first end; wherein a projection of the first portion of the second material layer onto the first material layer is located within the first portion of the first material layer; the projection of the second portion of the second material layer onto the first material layer overlaps the second portion of the first material layer; the first part of the first material layer and the first part of the second material layer form a first structure for changing the spot of the second light beam and outputting a third light beam; the second portion of the first material layer and the second portion of the second material layer form a second structure for transmitting a third light beam.
Optionally, the coupler further comprises: a second material layer and a third material layer extending along the light transmission direction; the second material layer is wrapped by the cladding layer, the second material layer is arranged on one side of the first material layer far away from the substrate, and the cladding layer is arranged between the first material layer and the second material layer; the second material layer includes a first portion and a second portion along a light transmission direction from the first end; wherein the projection of the second material layer onto the first material layer is located within the first portion of the first material layer; the third material layer is wrapped by the cladding layer, the third material layer is arranged on one side of the first material layer, which is close to the substrate, and the cladding layer is arranged between the first material layer and the third material layer; the third material layer comprises a first portion and a second portion along the light transmission direction from the first end; wherein the projection of the third material layer onto the first material layer is located within the first portion of the first material layer; the first focusing structure, the first portion of the second material layer, and the first portion of the third material layer form a first structure for focusing a first light beam received from an optical fiber coupled to the coupler, outputting a second light beam; the first portion of the first material layer, the second portion of the second material layer, and the second portion of the third material layer form a second structure for changing a spot of the second light beam and outputting a third light beam.
Optionally, a cladding layer is disposed between the first material layer and the second material layer.
Optionally, the coupler further comprises: a fourth material layer and a fifth material layer extending along the light transmission direction; the fourth material layer is wrapped by the cladding layer, the fourth material layer is arranged on one side of the second material layer far away from the first material layer, and the cladding layer is arranged between the fourth material layer and the second material layer; the fourth material layer comprises a first portion and a second portion along the light transmission direction from the first end; wherein the projection of the fourth material layer on the second material layer overlaps the second material layer; the fifth material layer is wrapped by the cladding layer, the fifth material layer is arranged on one side of the third material layer far away from the first material layer, and the cladding layer is arranged between the fifth material layer and the third material layer; the fifth material layer comprises a first portion and a second portion along the light transmission direction from the first end; wherein the projection of the fifth material layer on the third material layer overlaps the third material layer; the first focusing structure, the first portion of the second material layer, the first portion of the third material layer, the first portion of the fourth material layer, and the first portion of the fifth material layer form a first structure; the first portion of the first material layer, the second portion of the second material layer, the second portion of the third material layer, the second portion of the fourth material layer, and the second portion of the fifth material layer form a second structure.
Optionally, the first portion of the first material layer includes a second end and a third end along the light transmission direction from the first end, a dimension of the second end in the first direction is the same as a dimension of the third end in the first direction, and a dimension of the second end in the second direction is greater than a dimension of the third end in the second direction; wherein the first direction is perpendicular to the substrate, the second direction is parallel to the substrate and perpendicular to the light transmission direction; the second portion of the first material layer includes a fourth end and a fifth end along the light transmission direction from the first end, the fourth end has a dimension in the first direction that is the same as the dimension of the fifth end in the first direction, and the fourth end has a dimension in the second direction that is the same as the dimension of the fifth end in the second direction.
Optionally, the first portion of the first material layer includes a second end and a third end along the light transmission direction from the first end, a dimension of the second end in the first direction is the same as a dimension of the third end in the first direction, and a dimension of the second end in the second direction is greater than a dimension of the third end in the second direction; wherein the first direction is perpendicular to the substrate, the second direction is parallel to the substrate and perpendicular to the light transmission direction; the second part of the first material layer comprises a fourth end and a fifth end along the light transmission direction from the first end, the dimension of the fourth end in the first direction is the same as the dimension of the fifth end in the first direction, and the dimension of the fourth end in the second direction is the same as the dimension of the fifth end in the second direction; the first portion of the second material layer includes a sixth end and a seventh end along the light transmission direction from the first end, a dimension of the sixth end in the first direction is the same as a dimension of the seventh end in the first direction, and a dimension of the sixth end in the second direction is smaller than a dimension of the seventh end in the second direction; the second portion of the second material layer includes an eighth end and a ninth end from the first end in the light transmission direction, a dimension of the eighth end in the first direction being the same as a dimension of the ninth end in the first direction, and a dimension of the eighth end in the second direction being the same as a dimension of the ninth end in the second direction.
Optionally, the first portion of the first material layer includes a second end and a third end along the light transmission direction from the first end, a dimension of the second end in the first direction is the same as a dimension of the third end in the first direction, and a dimension of the second end in the second direction is greater than a dimension of the third end in the second direction; wherein the first direction is perpendicular to the substrate, the second direction is parallel to the substrate and perpendicular to the light transmission direction; the second part of the first material layer comprises a fourth end and a fifth end along the light transmission direction from the first end, the dimension of the fourth end in the first direction is the same as the dimension of the fifth end in the first direction, and the dimension of the fourth end in the second direction is the same as the dimension of the fifth end in the second direction; the first part of the second material layer comprises a sixth end along the light transmission direction from the first end, the sixth end is a light beam incident end, and the end face of the sixth end is a convex surface; the second portion of the second material layer includes a seventh end and an eighth end along the light transmission direction from the first end, the seventh end having a dimension in the first direction that is the same as the eighth end, the seventh end having a dimension in the second direction that is greater than the eighth end; the first part of the third material layer comprises a ninth end along the light transmission direction from the first end, the ninth end is a light beam incident end, and the end face of the ninth end is a convex surface; the second portion of the third material layer includes a tenth end and a tenth end along the light transmission direction from the first end, the tenth end having a dimension in the first direction that is the same as the dimension of the eleventh end in the first direction, the tenth end having a dimension in the second direction that is greater than the dimension of the tenth end in the second direction.
Optionally, the first portion of the first material layer includes a second end and a third end along the light transmission direction from the first end, a dimension of the second end in the first direction is the same as a dimension of the third end in the first direction, and a dimension of the second end in the second direction is greater than a dimension of the third end in the second direction; wherein the first direction is perpendicular to the substrate, the second direction is parallel to the substrate and perpendicular to the light transmission direction; the second part of the first material layer comprises a fourth end and a fifth end along the light transmission direction from the first end, the dimension of the fourth end in the first direction is the same as the dimension of the fifth end in the first direction, and the dimension of the fourth end in the second direction is the same as the dimension of the fifth end in the second direction; the first part of the second material layer comprises a sixth end and a seventh end along the light transmission direction from the first end, the size of the sixth end in the first direction is smaller than that of the seventh end in the first direction, and the size of the sixth end in the second direction is the same as that of the seventh end in the second direction; the second portion of the second material layer includes an eighth end and a ninth end from the first end in the light transmission direction, a dimension of the eighth end in the first direction being the same as a dimension of the ninth end in the first direction, and a dimension of the eighth end in the second direction being the same as a dimension of the ninth end in the second direction.
Optionally, the first portion of the first material layer includes a second end and a third end along the light transmission direction from the first end, a dimension of the second end in the first direction is the same as a dimension of the third end in the first direction, and a dimension of the second end in the second direction is smaller than a dimension of the third end in the second direction; wherein the first direction is perpendicular to the substrate, the second direction is parallel to the substrate and perpendicular to the light transmission direction; the second portion of the first material layer includes a fourth end and a fifth end along the light transmission direction from the first end, the fourth end has a dimension in the first direction that is the same as the dimension of the fifth end in the first direction, and the fourth end has a dimension in the second direction that is the same as the dimension of the fifth end in the second direction.
Optionally, the first material layer further includes a third portion disposed at the first end, and the first focusing structure is fabricated on the third portion of the first material layer.
Optionally, the first focusing structure comprises a lens and a grating array; the incident surface of the lens is convex.
Optionally, the radian of the incident surface of the lens is less than or equal to 100 degrees, and the chord length of the incident surface of the lens is greater than or equal to 5 micrometers.
Optionally, the size of the incident surface of the lens in the first direction is smaller than or equal to a second predetermined value, and the first direction is perpendicular to the substrate; the second predetermined value is L, l=λ/(2*n); λ is the wavelength of the first light beam and n is the refractive index of the material of the first focusing structure.
Optionally, the coupler further comprises a second focusing structure, the second focusing structure being disposed between the first focusing structure and the optical fiber; the second focusing structure is configured to focus a first light beam received from an optical fiber coupled to the coupler.
Optionally, the equivalent focal length of the second focusing structure and the first focusing structure is smaller than or equal to a third predetermined value, wherein the third predetermined value is F, f= (pi×ω1×ω2)/λ; where ω1 is the beam waist radius of the first beam, ω2 is the beam waist radius of the third beam, and λ is the wavelength of the first beam.
Optionally, the dimension of the second end in the first direction is less than or equal to a fourth predetermined value; the fourth predetermined value is L, l=λ/(2*n); λ is the wavelength of the first light beam, and n is the refractive index of the material of the first material layer.
Optionally, the focal length of the first focusing structure is a fifth predetermined value, and a dimension of the first portion of the first material layer in the light transmission direction is greater than or equal to the fifth predetermined value.
In a second aspect, there is provided a photonic integrated circuit comprising: a substrate and a coupler as in any of the first aspects above disposed on the substrate.
In a third aspect, there is provided an atomic molecular photophysical system comprising: a light source, an optical fiber, and a photonic integrated circuit as described in the second aspect above; the light source is used for generating a light beam and transmitting the light beam to the photonic integrated circuit through the optical fiber.
Optionally, the optical fiber and the photonic integrated circuit are fixedly connected through cured adhesive.
Optionally, a distance between a center line of a core of the optical fiber and a center line of a focusing structure in the photonic integrated circuit is less than or equal to a sixth predetermined value.
Drawings
FIG. 1 is a schematic structural diagram of an atomic molecular photophysical AMO system provided by an embodiment of the present application;
FIG. 2 is a schematic diagram of a coupler according to an embodiment of the present application;
FIG. 3 is a schematic diagram of a coupler according to another embodiment of the present application;
FIG. 4 is a schematic structural view of a coupler according to another embodiment of the present application;
FIG. 5 is a schematic diagram of a coupler according to another embodiment of the present application;
FIG. 6 is a schematic view of a focusing structure in a coupler according to still another embodiment of the present application;
FIG. 7 is a schematic diagram of a coupler according to another embodiment of the present application;
fig. 8 is a schematic structural view of a coupler according to still another embodiment of the present application;
FIG. 9 is a schematic diagram of a coupler according to still another embodiment of the present application;
FIG. 10 is a schematic diagram of a coupler according to another embodiment of the present application;
FIG. 11 is a schematic structural view of a coupler according to yet another embodiment of the present application;
FIG. 12 is a schematic diagram of a coupler according to still another embodiment of the present application;
FIG. 13 is a schematic diagram of a coupler according to another embodiment of the present application;
Fig. 14 is a schematic structural view of a coupler according to still another embodiment of the present application.
Detailed Description
The technical solutions of the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In embodiments of the present application, "at least one" means one or more, and "a plurality" means two or more. "and/or", describes an association relationship of an association object, and indicates that there may be three relationships, for example, a and/or B, and may indicate: a alone, a and B together, and B alone, wherein a, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one (one) of a, b or c may represent: a, b, c, a and b, a and c, b and c or a, b and c, wherein a, b and c can be single or multiple. In addition, in the embodiments of the present application, the words "first", "second", and the like do not limit the number and order.
Furthermore, in the embodiments of the present application, the terms "upper," "lower," and the like, are defined with respect to the orientation in which the components in the drawings are schematically disposed, and it should be understood that these directional terms are relative concepts, which are used for description and clarity with respect thereto, and which may be correspondingly varied according to the variation in the orientation in which the components in the drawings are disposed.
It should be noted that in the embodiments of the present application, words such as "exemplary" or "such as" are used to mean serving as an example, instance, or illustration. Any embodiment or design described herein as "exemplary" or "e.g." in an embodiment of the present application is not to be taken as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete fashion.
The technical scheme in the embodiment of the present application will be described below with reference to the accompanying drawings.
Atomic molecular photophysics (atomic molecule optics, AMO) is a new branch of near modern physics, mainly the discipline of studying interactions between light and substances or between substances, where atomic molecular photophysics AMO is generally the study of interactions between atoms, ions, molecules and light or between atoms, ions, molecules, to reveal the underlying quantum behavior.
The system for performing the atomic molecular photophysical AMO study is called an atomic molecular photophysical AMO system, and in the atomic molecular photophysical AMO system, optical devices and electronic components are generally included, where the optical devices include a light source, an optical amplifier, a light detector, an optical fiber connector (optical fiber connector), a coupler (coupler), and the like; electronic components include capacitors, resistors, diodes (diodes), transistors (bipolar junction transistor, BJTs), metal-oxide-semiconductor field effect transistors (MOSFETs), and the like. Currently, the development of atomic molecular photophysical AMO systems is towards functional partitioning, transportation control and electro-optical integration, and more atomic molecular photophysical AMO systems begin to use optical sub-circuits (photonics integrated circuit, PIC), and the photonic integrated circuits PIC can integrate a predetermined number of optical devices and electronic components together, so that possibility is provided for functional partitioning and electro-optical integration.
Referring to fig. 1, an embodiment of the present application provides a schematic structural diagram of an atomic molecular photophysical AMO system, wherein in the atomic molecular photophysical AMO system 10, a light source 30, an optical fiber 40 and a photonic integrated circuit PIC20 are included, the light source 30 is used to generate a light beam, and the light beam is transmitted through the optical fiber 40 into the photonic integrated circuit PIC20, and the photonic integrated circuit PIC20 is used to perform interaction between the light beam and an atom or an ion or a molecule.
In some embodiments, more or fewer devices may be included in the atomic molecular photophysical AMO system 10, which embodiments of the present application do not limit.
Exemplary atomic molecular photophysics AMO systems include cold atomic physical systems, quantum computing systems of reed burg atoms, quantum sensing systems, and ion trap quantum computing systems, to which embodiments of the application are not limited.
The cold atoms mentioned in the cold atom physical system have slow motion rate and less collision, so the cold atoms are easy to control, have low energy spectrum broadening and can improve measurement accuracy when being used for measurement. Secondly, the Debroil wavelength (de broglie wavelength) of the cold atoms is very long, which can show obvious quantum characteristics, and the coherence of the cold atoms is very strong, which can generate macroscopic quantum effects. Again, cold atoms tend to accumulate in a state of as low energy as possible, i.e. to produce Bose-einstein condensation (Bose-Einstein Condensation, BEC). Therefore, the cold atoms have wide application in various fields such as quantum precision measurement, quantum simulation, quantum computation and the like. The light source in the cold atomic physical system is used for generating a light beam, and transmitting the light beam to the photonic integrated circuit PIC in the cold atomic physical system through an optical fiber; the photonic integrated circuit PIC in the cold atom physical system is configured to form a cold atom in the photonic integrated circuit PIC according to a light beam generated by the light source, and then transmit the cold atom to a predetermined functional area, so as to implement predetermined functions such as quantum precision measurement, quantum simulation, quantum calculation, and the like by using the cold atom.
The Redberg atoms mentioned in the quantum computing system of the Redberg atoms are atoms with the outermost layer electrons in a high-excitation state, namely, the high-excitation state atoms with larger main quantum number n, wherein the Redberg atoms have the characteristics of large orbit radius, long radiation life, large polarization rate, larger dipole moment, strong interaction and the like. The quantum logic gate and the quantum bit can be realized based on the dipole interaction of the Redberg atoms, so that the quantum computation is realized. The light source in the quantum computing system of the Redberg atoms is used for generating a light beam, and transmitting the light beam to the photonic integrated circuit PIC in the quantum computing system of the Redberg atoms through an optical fiber; the photonic integrated circuit PIC in the quantum computing system of the reed-burg atoms is configured to excite the reed-burg atoms in the photonic integrated circuit PIC according to the light beam generated by the light source, and transmit the reed-burg atoms to a predetermined functional area, where the predetermined functional area uses the reed-burg atoms to implement a quantum logic gate and a quantum bit, thereby implementing a quantum computing function.
The quantum sensing system utilizes the characteristics that atoms can be accurately controlled and measured to realize the function of the precise sensor by utilizing the external change of the atoms perception. Currently, quantum sensing systems can be used to measure accuracy parameters such as acceleration, gravity, time, pressure, temperature, and magnetic field. Compared with the common sensor, the quantum sensing system has greatly improved sensitivity, accuracy and stability, so that the quantum sensing system has important application in the fields of aerospace, climate monitoring, construction and the like. The light source in the quantum sensing system is used for generating a light beam, and the light beam is transmitted to the photonic integrated circuit PIC in the quantum sensing system through an optical fiber; the photonic integrated circuit PIC in the quantum sensing system is configured to generate a quantum signal for measurement from a light beam generated by a light source, and output the quantum signal. In some embodiments, the photonic integrated circuit PIC in the quantum sensing system is further integrated with a functional module for processing the quantum signal, so the photonic integrated circuit PIC in the quantum sensing system is further used for processing the quantum signal to determine the measurement value.
Ion traps in ion trap quantum computing systems are formed by confining ions within a finite space using an electromagnetic field. The ion trap quantum calculation is to act on ions in the ion trap through light matched with ion energy level transition to realize quantum logic gate and quantum bit, so as to realize calculation function. The ion trap quantum computing system has the advantages of longer coherence time, higher fidelity of a quantum logic gate, high repeatability of quantum bits and the like. The light source in the ion trap quantum computing system is used for generating a light beam, and the light beam is transmitted to the photon integrated circuit PIC in the ion trap quantum computing system through an optical fiber; the photon integrated circuit PIC in the ion trap quantum computing system is used for forming an ion trap, and ions in the ion trap are acted according to light beams generated by a light source to generate a quantum logic gate and a quantum bit, so that a computing function is realized.
Illustratively, referring to fig. 1, in order to allow the light beam transmitted in the optical fiber 40 to be transmitted into the photonic integrated circuit PIC20, a coupler is often disposed in the photonic integrated circuit PIC20, wherein the coupler is configured to receive the light beam transmitted by the optical fiber 40 to the photonic integrated circuit PIC20 and couple the light beam into the photonic integrated circuit PIC 20.
In other embodiments, photonic integrated circuit PIC20 may further include optical modulators, optical switches, optical routing, etc., wherein photonic integrated circuit PIC20 in embodiments of the present application may further include more or fewer optical devices, and embodiments of the present application are not limited in this respect.
Referring to fig. 1, the photonic integrated circuit PIC20 includes a substrate 201 and a semiconductor material layer 203 disposed on the substrate 201, wherein the semiconductor material layer 203 is used to form various optical devices such as couplers and the like, as viewed from the material layer structure.
In some embodiments, the photonic integrated circuit PIC20 further includes a buried oxide layer 202 disposed between the substrate 201 and the layer of semiconductor material 203. In other embodiments, the side of the semiconductor material layer 203 remote from the substrate 201 may be further provided with other material layers, such as an insulating layer, a metal wiring layer, etc., where the material layer structure of the photonic integrated circuit PIC20 shown in fig. 1 is illustrative and does not constitute a limitation on the material layers in the photonic integrated circuit PIC 20.
At present, the wavelength of the light beam generated by the light source 30 in the atomic molecular photophysical AMO system 10 is gradually shortened, and for example, in the ion trap quantum computing system, the light beam for acting on ions in the ion trap is visible light or even ultraviolet light, and the wavelength of the light beam is much shorter than that of the light beam for communication, so that when the photonic integrated circuit PIC20 in the ion trap quantum computing system is manufactured, the existing silicon-based photonic technology platform cannot be used for manufacturing due to the reduction of the wavelength. The existing silicon-based photon technology platform is not applicable to the following three problems when the wavelength of a light beam is reduced:
1. Material absorption problems.
The silicon-based photonic technology platform is mainly made of silicon, and the absorption of silicon to a communication long-wavelength light beam is relatively small, but as the wavelength of the light beam is reduced, the absorption of silicon to a short-wavelength light beam is increased, and when the light beam is mostly absorbed by silicon materials, the function of the photonic integrated circuit PIC is limited.
The solution to this problem is to replace the material with a material transparent to a light beam of a predetermined wavelength, for example, silicon nitride Si 3N4 material may be selected for use when the wavelength of the light beam is greater than 390 nanometers (nm) and aluminum oxide Al 2O3 material may be selected for use when the wavelength of the light beam is less than 390 nm. Thereby reducing absorption of the short wavelength beam by the material.
2. Machining precision.
The processing precision affects the transmission efficiency of the light beam in the photonic integrated circuit PIC, and the processing precision requirement of the light beam with a long wavelength for communication is relatively low, while the processing precision requirement of the light beam with a short wavelength is high.
The solution to this problem is to process the light sub-assembly circuit PIC with a semiconductor device having higher accuracy, for example, when performing photolithography on the light sub-assembly circuit PIC, photolithography is performed by using a deep ultraviolet (deep ultra violet, DUV) lithography device or an extreme ultraviolet (extreme ultra violet, EUV) lithography device preferentially, or photolithography is performed by using an ion beam lithography device to construct an ion blocking layer (electron blocking layer, EBL) so as to improve the processing accuracy.
3. Package tolerance issues between the optical fiber and the photonic integrated circuit PIC.
Wherein the packaging tolerance includes both packaging precision along the optical fiber direction (the direction along the x-axis of the photonic integrated circuit PIC20 shown in fig. 1) and alignment precision perpendicular to the optical fiber direction (i.e., the cross-sectional direction constituted by the yz-axis between the contact surfaces of the optical fiber 40 and the photonic integrated circuit PIC20 shown in fig. 1), wherein the packaging precision is the dimension of the distance between the end surface of the optical fiber 40 near the photonic integrated circuit PIC20 and the end surface of the photonic integrated circuit PIC20 near the optical fiber 40 on the x-axis, and the alignment precision is the distance between the center of the mode field of the end surface of the optical fiber 40 near the photonic integrated circuit PIC20 and the center of the mode field of the end surface of the optical transmission structure near the core in the photonic integrated circuit PIC 20.
In the direction along the optical fiber, the packaging accuracy is required to fall at least within the rayleigh length range of the light beam transmitted in the optical fiber 40, wherein the rayleigh length of the light beam is related to the beam waist radius of the light beam as follows:
Where z is the rayleigh length, w 0 is the beam waist radius of the beam transmitted in the optical fiber 40, and λ is the wavelength of the beam transmitted in the optical fiber 40.
When the visible light polarization maintaining fiber is used as the optical fiber 40 in the direction perpendicular to the optical fiber, the mode field diameter (mode FIELD DIAMETER, MFD) of the fiber core of the visible light polarization maintaining fiber is relatively small, so that the beam waist radius of the light beam (the light beam is a gaussian beam) emitted from the optical fiber 40 is correspondingly small; it is desirable to have the size of the optical transmission structure in photonic integrated circuit PIC20 (which may be, for example, the size of the optical waveguide in photonic integrated circuit PIC 20) decrease in synchronization with the wavelength size of the optical beam transmitted in optical fiber 40.
In addition, the center line of the core of the optical fiber 40 near the end face of the photonic integrated circuit PIC20 should be as flush as possible with the center line of the end face of the optical transmission structure in the photonic integrated circuit PIC20 near the core, or there should be a small alignment gap. Referring to table 1, table 1 shows the alignment accuracy requirements required for the optical transmission structure in the single mode optical fiber and photonic integrated circuit PIC20 of different wavelengths to have a loss of <0.5dB after packaging.
TABLE 1
Wavelength (nm) Girdle radius (mum) Rayleigh Length (μm) Divergence angle (rad) Alignment accuracy requirement (mum)
1550 4.5 41.02 0.11 1
780 2 16.10 0.12 0.4
390 1 8.05 0,12 0.2
Currently, in the direction perpendicular to the optical fiber, the package alignment accuracy enabled by the silicon-based photonic technology is about 0.5 μm, as shown in table 1, as the wavelength of the light beam transmitted in the optical fiber 40 decreases, the alignment accuracy requirement of the photonic integrated circuit PIC is higher and higher, and the alignment accuracy requirement is reduced beyond the current silicon-based photonic process accuracy capability, for example, when the wavelength of the light beam transmitted in the optical fiber 40 is 780nm, the alignment accuracy requirement of the photonic integrated circuit PIC is 0.4 μm; at 390nm, the photonic integrated circuit PIC requires 0.2 μm alignment accuracy. The accuracy of the package alignment is smaller than 0.5 mu m which can be achieved by the silicon-based photonics technology at present.
For this reason, measures other than the process are considered to solve the package tolerance problem between the optical fiber 40 and the photonic integrated circuit PIC20, thereby improving the coupling efficiency between the optical fiber and the photonic integrated circuit PIC.
In practice, the coupling between the optical fiber 40 and the photonic integrated circuit PIC20 is related not only to the material and the processing technology of the photonic integrated circuit PIC20 itself, but also to the processing precision of the peripheral optical fiber array, the packaging glue, etc., so that the actual alignment precision between the core of the optical fiber 40 and the photonic integrated circuit PIC20 will be required to be higher than the theoretical value shown in table 1.
At present, coupling is often realized between the optical fiber and the photonic integrated circuit PIC through a coupler, the coupler comprises an edge coupler and a grating coupler, wherein the grating coupler is flexible in setting position, and can be fixedly connected with the optical fiber 40 through the grating coupler at any position of the photonic integrated circuit PIC so as to realize coupling, but the grating coupler is sensitive to a process and has lower coupling efficiency. The edge coupler has a simple structure and is easy to realize, so that the edge coupler is widely applied to the photonic integrated circuit PIC.
Referring to fig. 2, an embodiment of the present application provides a schematic structural diagram of an edge coupler 21, where, referring to fig. 1, the edge coupler 21 is disposed in a region where the photonic integrated circuit PIC20 is coupled to the optical fiber 40, and the edge coupler 21 is disposed in the semiconductor material layer 203. As shown with reference to fig. 2, the edge coupler 21 includes a mode spot-size converter 22 and a waveguide 23. The photonic integrated circuit PIC20 is provided with an optical transmission structure, which includes a waveguide 23 in the edge coupler 21 and waveguides of other optical devices provided in the photonic integrated circuit PIC, where the waveguides of the other optical devices provided in the photonic integrated circuit PIC may be, for example, waveguides in an optical modulator, waveguides in an optical switch, waveguides in an optical route, and the like. The optical transmission structure in the photonic integrated circuit PIC20 is used to transmit the first light beam that the optical fiber 40 transmits to the photonic integrated circuit PIC 20. Referring to fig. 2, the optical transmission structure in photonic integrated circuit PIC20 includes waveguide 23 in edge coupler 21.
Specifically, the mode spot changer 22 in the edge coupler 21 shown in fig. 2 is used to couple the optical fiber 40 and the waveguide 23 in the edge coupler 21, and the mode spot changer 22 is used to change the mode spot size of the first light beam transmitted from the optical fiber 40 to the edge coupler 21 into the second light beam, wherein the mode spot size of the second light beam is suitable for transmission in the waveguide 23, and the waveguide 23 is used to transmit the second light beam.
Illustratively, when the edge coupler 21 is coupled to the optical modulator, then the waveguide 23 of the edge coupler 21 is coupled to the waveguide of the optical modulator, the waveguide 23 being configured to transmit the second light beam to the waveguide of the optical modulator. When the edge coupler 21 is coupled to the optical switch, the waveguide 23 of the edge coupler 21 is then connected to the waveguide of the optical switch, the waveguide 23 being used for transmitting the second light beam to the waveguide of the optical switch. When the edge coupler 21 is coupled to the optical route, the waveguide 23 of the edge coupler 21 is connected to the waveguide of the optical route, the waveguide 23 being arranged to transmit the second light beam to the waveguide of the optical route.
Exemplary, referring to FIG. 3, an embodiment of the present application provides a schematic material structure of the edge coupler 21, wherein (a) in FIG. 3 is a cross-sectional view along AA' of FIG. 1, which is cut through the edge coupler 21 and a portion of the optical fiber 40 in the photonic integrated circuit PIC 20; fig. 3 (b) is a top view of fig. 1 along the SA region, which includes only the edge coupler 21 in the photonic integrated circuit PIC20, and which also includes a portion of the optical fiber 40.
Specifically, referring to fig. 3, the edge coupler includes a cladding layer 211 provided on a substrate 201 of the photonic integrated circuit PIC20, a material layer 212 extending in the light transmission direction, and a material layer 213. Wherein the refractive index of the material layer 212 is greater than the refractive index of the material of the cladding 211, the refractive index of the material layer 213 is greater than the refractive index of the material of the cladding 211, the material layer 212 is wrapped by the cladding 211, and the a-end of the material layer 212 faces the core 41 in the optical fiber 40; the material layer 213 is surrounded by the cladding layer 211, the material layer 213 being arranged on the side of the material layer 212 remote from the substrate 201.
Wherein, referring to fig. 3, the light transmission direction of the photonic integrated circuit PIC20 is x-axis, along the x-axis from the a-end, the material layer 212 includes a first portion 212a and a second portion 212b, and the material layer 213 includes a first portion 213a and a second portion 213b, wherein the projection of the first portion 213a of the material layer 213 on the material layer 212 is located in the first portion of the material layer 212, and the projection of the second portion 213b of the material layer 213 on the material layer 212 overlaps with the second portion 212b of the material layer 212. The first portion 212a of the material layer 212 and the first portion 213a of the material layer 213 form the structure of the spot-size converter 22 shown in fig. 2, and the second portion 212b of the material layer 212 and the second portion 213b of the material layer 213 form the structure of the waveguide 23 shown in fig. 2. Illustratively, the first portion 212a of the material layer 212 and the first portion 213a of the material layer 213 are configured to alter a mode spot of a first light beam received from the optical fiber 40, generate a second light beam, and output the second light beam; the second portion 212b of the material layer 212 and the second portion 213b of the material layer 213 are adapted to transmit a second light beam.
Specifically, referring to FIG. 3, along the x-axis from the a-terminus, a first portion 212a of the material layer 212 includes a b-terminus and a c-terminus, wherein the b-terminus of the first portion 212a of the material layer 212 coincides with the a-terminus of the material layer 212. The dimension of the b-end in the z-axis is the same as the dimension of the c-end in the z-axis, the z-axis being perpendicular to the substrate 201 and the z-axis being perpendicular to the x-axis. The dimension of the b-end on the y-axis is greater than the dimension of the c-end on the y-axis, the y-axis being parallel to the substrate 201 and the y-axis being perpendicular to the x-axis. Along the x-axis from the a-end, the second portion 212b of the material layer 212 includes a d-end and an e-end, wherein the d-end of the second portion 212b of the material layer 212 coincides with the c-end of the first portion 212a of the material layer 212. The dimension of the d-end in the z-axis is the same as the dimension of the e-end in the z-axis. The dimension of the d-end on the y-axis is the same as the dimension of the c-end on the y-axis.
Specifically, referring to FIG. 3, a first portion 213a of material layer 213 includes an f-terminal and a g-terminal along the x-axis from the a-terminal. The projection of the first portion 213a of the material layer 213 onto the material layer 212 is located within the first portion of the material layer 212, specifically the projection of the g-end onto the material layer 212 overlaps the c-end, and the projection of the f-end onto the material layer 212 is located between the b-end and the c-end. The dimension of the f-end on the z-axis is smaller than the dimension of the g-end on the z-axis, and the dimension of the f-end on the y-axis is the same as the dimension of the g-end on the y-axis. Along the x-axis from the a-end, the second portion 213b of the material layer 213 comprises an h-end and an i-end, wherein the h-end of the second portion 213b of the material layer 213 coincides with the g-end of the first portion 213a of the material layer 213, and the dimension of the h-end in the z-axis is the same as the dimension of the i-end in the z-axis. The dimension of the h-terminal on the y-axis is the same as the dimension of the i-terminal on the y-axis.
Wherein, along the x-axis from the a-end, the dimension of the b-end on the z-axis is the same as the dimension of the c-end on the z-axis, the d-end coincides with the c-end, and the dimension of the d-end on the z-axis is the same as the dimension of the e-end on the z-axis. Thus, the dimension of material layer 212 in the z-axis remains unchanged at all times. The dimension of the b end on the y axis is larger than that of the c end on the y axis, the d end coincides with the c end, and the dimension of the d end on the y axis is the same as that of the e end on the y axis. Thus, the dimension of material layer 212 in the y-axis gradually decreases to a minimum and remains unchanged.
Wherein, along the x-axis from the a-end, the size of the f-end on the z-axis is smaller than the size of the g-end on the z-axis, the g-end coincides with the h-end, and the size of the h-end on the z-axis is the same as the size of the i-end on the z-axis. Thus, the dimension of the material layer 213 in the z-axis gradually increases to a maximum value and remains unchanged. The dimension of the f end on the y axis is identical to the dimension of the g end on the y axis, the g end coincides with the h end, and the dimension of the h end on the y axis is identical to the dimension of the i end on the y axis. Thus, the dimension of the material layer 213 in the y-axis remains unchanged.
In some embodiments, the dimension of material layer 212 in the z-axis from the a-terminus along the x-axis is 20nm or more to 50nm or less.
In some embodiments, the dimension in the z-axis of material layer 213 increases from 0 to 200nm along the x-axis from the a-terminus.
Illustratively, along the x-axis from the a-end, the first portion 212a of the material layer 212 includes a first sub-portion 212a1 and a second sub-portion 212a2, wherein the first portion 212a of the material layer 212 further includes a k-end between the b-end and the c-end, the k-end being configured to space the first sub-portion 212a1 and the second sub-portion 212a2. More specifically, the first subsection 212a1 is a region of the first section 212a of the layer of material 212 defined between the b-and k-ends and the second subsection 212a2 is a region of the first section 212a of the layer of material 212 defined between the k-and c-ends. Wherein the dimension of the b-end on the y-axis is greater than the dimension of the c-end on the y-axis, specifically the dimension of the b-end on the y-axis is greater than the dimension of the k-end on the y-axis, the dimension of the first sub-portion 212a1 on the y-axis is gradually reduced, the dimension of the k-end on the y-axis is the same as the dimension of the c-end on the y-axis, and the dimension of the second sub-portion 212a2 on the y-axis is unchanged.
In addition, the projection of the f-terminal onto the material layer 212 is located between the b-terminal and the c-terminal, and more specifically, the projection of the f-terminal onto the material layer 212 overlaps the k-terminal. Wherein the dimension of the f-end in the z-axis is smaller than the dimension of the g-end in the z-axis. That is, it is shown that the first portion 213a of the material layer 213 starts to increase in size in the z-axis after the first portion 212a of the material layer 212 completes its size reduction in the y-axis.
In the edge coupler 21 shown in fig. 3, the first portion 212a of the material layer 212 and the first portion 213a of the material layer 213 are formed in the structure of the spot size converter 22 shown in fig. 2, and the size of the end of the first portion 212a of the material layer 212 near the core 41 of the optical fiber 40 in the y-axis is larger, so that the spot area of the end face of the spot size converter 22 near the core 41 is larger, the first light beam transmitted in the core 41 is easily received, and the energy of the first light beam is mostly localized in the material layer 212. And the dimension of the first portion 212a of the material layer 212 in the y-axis remains unchanged as the material layer 212 extends along the x-axis from a substantial decrease to a minimum. In addition, as the dimension of the material layer 212 in the y-axis decreases to a minimum, the dimension of the first portion 213a of the material layer 213 in the z-axis gradually increases, such that the first beam may achieve low-loss adiabatic transfer in the spot-changer 22 as the spot-changer 22 changes the spot of the first beam to generate the second beam.
However, to achieve lower losses with the edge coupler shown in fig. 3, it is often desirable for the first portion 212a of the material layer 212 to extend a longer distance along the x-axis so that the first portion 212a of the material layer 212 gradually decreases in size in the y-axis; it is also desirable that the first portion 213a of the material layer 213 extend a longer distance along the x-axis so that the first portion 213a of the material layer 213 gradually increases in size in the z-axis. Larger dimensions of photonic integrated circuit PIC20 in the x-axis are occupied, resulting in an increase in the area of photonic integrated circuit PIC 20.
In addition, the energy of the light beam transmitted from the core 41 of the optical fiber 40 to the spot-size converter 22 is mainly distributed in the cladding 211, only a part of the energy can be distributed in the material layer 212, the energy of the light beam transmitted from the spot-size converter 22 is relatively divergent, and the alignment accuracy of the core 41 and the photonic integrated circuit PIC20 is relatively small, and when the actual alignment accuracy of the core 41 and the photonic integrated circuit PIC20 becomes large, the coupling efficiency may be greatly reduced, and even coupling failure may occur.
By way of example, referring to fig. 4, an embodiment of the present application provides a schematic material structure of another edge coupler 21, where (a) in fig. 4 is a cross-sectional view along AA' of fig. 1, the cross-sectional view being taken through the edge coupler 21 and a portion of the optical fiber 40 in the photonic integrated circuit PIC 20; fig. 4 (b) is a top view of fig. 1 along the SA region, which includes only the edge coupler 21 in the photonic integrated circuit PIC20, and which also includes a portion of the optical fiber 40.
Specifically, referring to fig. 4, the edge coupler 21 includes a cladding layer 211 provided on the substrate 201 of the photonic integrated circuit PIC20, and a material layer 212 extending in the light transmission direction. Wherein the refractive index of the material layer 212 is greater than the refractive index of the material of the cladding 211, the material layer 212 is surrounded by the cladding 211, and the a-end of the material layer 212 faces the core 41 in the optical fiber 40.
Referring to fig. 4, the light transmission direction of the photonic integrated circuit PIC20 is the x-axis, and the material layer 212 includes a first portion 212a and a second portion 212b along the x-axis from the a-end. The first portion 212a of the material layer 212 forms the structure of the spot-size converter 22 shown in fig. 2, and the second portion 212b of the material layer 212 forms the structure of the waveguide 23 shown in fig. 2. Illustratively, the first portion 212a of the material layer 212 is configured to alter the mode spot of the first light beam received from the optical fiber 40, generate a second light beam, and output the second light beam; a second portion 212b of the material layer 212 is used to transmit a second light beam.
Specifically, referring to FIG. 4, along the x-axis from the a-terminus, a first portion 212a of the material layer 212 includes a b-terminus and a c-terminus, wherein the b-terminus of the first portion 212a of the material layer 212 coincides with the a-terminus of the material layer 212. The dimension of the b-end in the z-axis is the same as the dimension of the c-end in the z-axis, the z-axis being perpendicular to the substrate 201 and the z-axis being perpendicular to the x-axis. The dimension of the b-end on the y-axis is smaller than the dimension of the c-end on the y-axis, the y-axis being parallel to the substrate 201 and the y-axis being perpendicular to the direction of the x-axis. Along the x-axis from the a-end, the second portion 212b of the material layer 212 includes a d-end and an e-end, wherein the d-end of the second portion 212b of the material layer 212 coincides with the c-end of the first portion 212a of the material layer 212. The dimension of the d-end in the z-axis is the same as the dimension of the e-end in the z-axis. The dimension of the d-end on the y-axis is the same as the dimension of the e-end on the y-axis.
Wherein the dimension of the b-end in the y-axis is smaller than the dimension of the c-end in the y-axis, the d-end coincides with the c-end, and the dimension of the d-end in the y-axis is the same as the dimension of the e-end in the y-axis, so that the dimension of the material layer 212 in the y-axis is gradually increased to a maximum value and then remains unchanged.
Wherein the dimension of the b-end in the z-axis and the dimension of the c-end in the z-axis extend from the a-end along the x-axis, the d-end coincides with the c-end, and the dimension of the d-end in the z-axis is the same as the dimension of the e-end in the z-axis, and therefore the dimension of the material layer 212 in the z-axis remains unchanged.
In the edge coupler 21 shown in fig. 4, the first portion 212a of the material layer 212 is formed in the structure of the spot size converter 22, and the first portion 212a of the material layer 212 has a larger size in the z-axis near the end of the core 41 of the optical fiber 40, so that the spot size near the end face of the spot size converter 22 of the core 41 is larger, and the first light beam transmitted in the core 41 is easily received, wherein the energy of the first light beam is mostly in the cladding. And as the first portion 212a of the material layer 212 extends along the x-axis, the first portion 212a of the material layer 212 gradually increases in size in the y-axis so that energy of the first beam may be localized into the structure of the waveguide 23 formed by the second portion 212b of the material layer 212, enabling the spot-changer 22 to change the spot of the first beam to generate the second beam, the first beam may enable low-loss adiabatic transfer in the spot-changer 22. However, to achieve lower losses with the edge coupler shown in fig. 4, it is often desirable for the first portion 212a of the material layer 212 to extend a longer distance along the x-axis so that the first portion 212a of the material layer 212 increases in size in the y-axis. Larger dimensions of photonic integrated circuit PIC20 in the x-axis are occupied, resulting in an increase in the area of photonic integrated circuit PIC 20.
In addition, the energy of the light beam transmitted from the core 41 of the optical fiber 40 to the spot-size converter 22 is mainly distributed in the cladding 211, only a part of the energy can be distributed in the material layer 212, the energy of the light beam transmitted from the spot-size converter 22 is relatively divergent, and the alignment accuracy of the core 41 and the photonic integrated circuit PIC20 is relatively small, and when the actual alignment accuracy of the core 41 and the photonic integrated circuit PIC20 becomes large, the coupling efficiency may be greatly reduced, and even coupling failure may occur.
To this end, an embodiment of the present application provides a coupler, and referring to fig. 5, an embodiment of the present application provides a schematic structural diagram of a coupler 50, wherein, referring to fig. 1, in an atomic molecular optical physical ANO system 10, the coupler 50 is disposed in a region where a photonic integrated circuit PIC20 is coupled to an optical fiber 40, and the coupler 50 is disposed in a semiconductor material layer 203. As shown in fig. 5, the coupler 50 includes a focusing structure 51, a spot-size converter 52, and a waveguide 53. The photonic integrated circuit PIC20 is provided with an optical transmission structure, and the optical transmission structure includes a waveguide 53 in the coupler 50 and a waveguide of other optical devices provided in the photonic integrated circuit PIC20, where the waveguide of the other optical devices provided in the photonic integrated circuit PIC20 may be, for example, a waveguide in an optical modulator, a waveguide in an optical switch, a waveguide in an optical route, and the like. The optical transmission structure in the photonic integrated circuit PIC20 is used to transmit the optical beam transmitted by the optical fiber 40 to the photonic integrated circuit PIC 20. Referring to fig. 5, the optical transmission structure in photonic integrated circuit PIC20 includes a waveguide 53 in coupler 50.
Specifically, referring to fig. 5, a focusing structure 51 is provided for focusing a first light beam received from the optical fiber 40 coupled to the coupler 50, generating a second light beam, and outputting the second light beam. The spot-size converter 52 in the coupler 50 is configured to change the spot size of the second light beam, generate a third light beam, and output the third light beam, wherein the spot size of the third light beam is suitable for transmission in the waveguide 53. A waveguide 53 for transmitting the third light beam.
Illustratively, when the coupler 50 is coupled to the optical modulator, the waveguide 53 of the coupler 50 is coupled to the waveguide of the optical modulator, the waveguide 53 being configured to transmit the third light beam to the waveguide of the optical modulator. When the coupler 50 is coupled to the optical switch, the waveguide 53 of the coupler 50 is then connected to the waveguide of the optical switch, the waveguide 53 being used for transmitting the third light beam to the waveguide of the optical switch. When the coupler 50 is coupled to the optical path, the waveguide 53 of the coupler 50 is then connected to the waveguide of the optical path, the waveguide 53 being used to transmit the third light beam to the waveguide of the optical path.
By way of example, referring to fig. 6, an embodiment of the present application provides a schematic diagram of a focusing structure, wherein a first light beam is transmitted to the photonic integrated circuit PIC20 by the optical fiber 40, the first light beam is first incident on the focusing structure 51, and an incident surface of the focusing structure 51 receives the first light beam, wherein, as shown in fig. 6, an energy distribution of the first light beam is relatively dispersed, and the focusing structure 51 can implement focusing of energy of the first light beam, so that the energy of the first light beam is concentrated to generate a second light beam, and referring to fig. 6, the energy of the second light beam is gradually concentrated.
The focusing structure 51 may be a lens or a grating array, as shown in fig. 6, where the focusing structure may be a lens, the shape of the lens is an arc sector, the incident surface of the lens is a convex surface, and the exit surface of the lens is a plane; or the lens may be circular in shape, more specifically elliptical, with the entrance face of the lens being convex and the exit face of the lens also being convex. The focusing structure may also be a grating array, where a plurality of gratings are arranged in the grating array, and the gratings may change the propagation direction of the light beam, and when different gratings in the grating array change the direction of the light beam to a predetermined point, the grating array may also implement focusing of the light beam.
Exemplary, referring to FIG. 7, an embodiment of the present application provides a schematic material structure of a coupler 50, wherein (a) in FIG. 7 is a cross-sectional view along AA' of FIG. 1, which is taken through coupler 50 and a portion of optical fiber 40 in photonic integrated circuit PIC 20; fig. 7 (b) is a top view of fig. 1 along the SA region, which includes only the coupler 50 in the photonic integrated circuit PIC20, and which also includes a portion of the optical fiber 40.
Wherein fig. 8-14 also show schematic material structures of the coupler 50, and (a) in any of fig. 8-14 is a cross-sectional view along AA' of fig. 1, which is cut through the coupler 50 and a portion of the optical fiber 40 in the photonic integrated circuit PIC 20; fig. 8 to 14 (b) is a top view of fig. 1 along the SA region, which includes only the coupler 50 in the photonic integrated circuit PIC20, and which also includes a portion of the optical fiber 40. And will not be described in detail later.
Referring to fig. 7, the edge coupler 50 includes a focusing structure 51 and a cladding layer 501 disposed on a substrate 201; and further comprises a layer of material 502 extending in the light transmission direction. Illustratively, the material of the focusing structure 51 includes polyimide, SU8 photoresist, wherein polyimide or SU8 photoresist is a high refractive index composite material as well as an organic material. For example, polyimide or SU8 photoresist may be dropped on the sidewalls of photonic integrated circuit PIC20 to form focusing structure 51, wherein the end of focusing structure 51 adjacent to core 41 of optical fiber 40 is convex. Illustratively, the materials of material layer 502 include: silicon nitride (Si 3N 4), hafnium oxide (HfO 2), lithium niobate (LiNbO 3), aluminum nitride (AlN), and aluminum oxide (Al 2O 3), and the material of the cladding layer 501 includes silicon oxide, and the dimension of the cladding layer in the z-axis is 6 μm or more and 10 μm or less. Wherein the refractive index of the material layer 502 is greater than the refractive index of the material of the cladding layer 501.
The material layer 502 is surrounded by a cladding layer 501, the a-end of the material layer 502 being directed towards the focusing structure 51. Illustratively, it may be that the a-end of the material layer 502 is exposed outside the cladding layer 501, and the a-end of the material layer 502 is in contact with the focusing structure 51. Illustratively, the accuracy of the encapsulation of the core 41 of the optical fiber 40 with the coupler 50 in the photonic integrated circuit PIC20 is less than or equal to the rayleigh length of the first optical beam transmitted in the optical fiber 40.
From the a-end along the light transmission direction, the material layer 502 includes a first portion 502a and a second portion 502b; a focusing structure 51 for focusing the first light beam received from the optical fiber 40 coupled with the coupler 50 and outputting a second light beam; a first portion 502a of the material layer 502 for changing a spot of the second light beam and outputting a third light beam; a second portion 502b of the material layer 502 is used for transmitting a third light beam.
Illustratively, the focal length of the focusing structure 51 is equal to or less than a predetermined value 1, where the predetermined value 1 is F, f= (pi ω1 ω2)/λ; where ω1 is the beam waist radius of the first beam, ω2 is the beam waist radius of the third beam, and λ is the wavelength of the first beam. When the focal length of the focusing structure 51 is less than or equal to the predetermined value 1, the coupler 50 can achieve short focal length focusing of the first light beam received from the optical fiber 40, so that the distance between the material layer 502 and the focusing structure can be set to be relatively short, and the structure of the coupler 50 is more compact.
Illustratively, referring to fig. 7, the focusing structure 51 may be attached to a sidewall of the photonic integrated circuit PIC 20. Wherein the optical fiber 40 is coupled to the sidewall, specifically, the incident surface of the focusing structure 51 faces the optical fiber 40, and the a-end of the material layer 502 faces the focusing structure, wherein a distance between a center line of the focusing structure 51 and a center line of the core 41 in the optical fiber 40 is less than or equal to a predetermined value 2, specifically, the center line of the focusing structure 51 and the center line of the core 41 in the optical fiber 40 need to be aligned as much as possible, so that as much energy of the first light beam transmitted to the photonic integrated circuit PIC20 by the optical fiber is transmitted to the focusing structure 51. The distance between the center line of the focusing structure 51 and the center line of the material layer 502 is less than or equal to the predetermined value 3, specifically, the center line of the focusing structure 51 and the center line of the material layer 502 need to be aligned as much as possible, so that the energy of the second light beam output by the focusing structure after focusing the first light beam is transmitted into the material layer 502 as much as possible. The specific values of the predetermined value 2 may be the same or different in different couplers 50, the specific values of the predetermined value 3 may be the same or different in different couplers 50, and the predetermined value 2 and the predetermined value 3 may be equal or different, which is not limited in the embodiment of the present application.
Illustratively, referring to fig. 7, according to the placement position shown in fig. 7, where the light transmission direction of the photonic integrated circuit PIC20 is the x-axis, along the x-axis from the a-end, the material layer 502 includes a first portion 502a and a second portion 502b, the first portion 502a of the material layer 502 forms the structure of the spot-size converter 52 shown in fig. 5, and the second portion 502b of the material layer 502 forms the structure of the waveguide 53 shown in fig. 5. Illustratively, the first portion 502a of the material layer 502 is configured to alter a spot of the second beam, generate a third beam, and output the third beam; the second portion 502b of the material layer 502 is used for transmitting a third light beam.
In the coupler 50, the focusing structure 51 and the cladding layer 501 disposed on the substrate 201 are included, the cladding layer 501 is wrapped with a material layer 502 extending along the light transmission direction, and the a end (also called a first end) of the material layer 502 faces the focusing structure 51, and the material layer 502 includes a first portion 502a and a second portion 502b along the light transmission direction from the a end, so that the light transmission path of the first light beam in the coupler 50 is: focusing structure 51-a first portion 502a of material layer 502-a second portion 502b of material layer 502. When the coupler 50 is coupled with the optical fiber 40, the optical fiber 40 may transmit a first light beam to the coupler 50, wherein the focusing structure 51 first receives the first light beam, the focusing structure 51 focuses the energy of the first light beam, generates a second light beam, and outputs the second light beam to the first portion 502a of the material layer 502, the first portion 502a of the material layer 502 is used to change a mode spot of the second light beam, generate a third light beam, and output the third light beam. The original first beam has a spot size matching the core 41 of the optical fiber 40, and the second beam is only more energy-intensive than the first beam, so that the spot size of the second beam can be considered to be matching the core 41 of the optical fiber 40, and the first portion 502a of the material layer 502 is used to change the spot of the second beam and then output the third beam, and the spot size of the third beam is matched with the second portion 502b of the material layer 502, and the second portion 502b of the material layer 502 is used to transmit the third beam to other places. In such a coupler 50, due to the focusing structure 51, the energy of the first light beam transmitted to the coupler 50 by the optical fiber 40 is focused by the focusing structure and then transmitted to the material layer 502, so that the energy proportion of the first light beam received in the material layer 502 is improved, and the coupling efficiency of the coupler 50 is further improved.
Specifically, referring to fig. 7, along the x-axis from the a-end, a first portion 502a of the material layer 502 includes a b-end and a c-end, wherein the b-end of the first portion 502a of the material layer 502 coincides with the a-end of the material layer 502. The dimension of the b-end in the z-axis is the same as the dimension of the c-end in the z-axis, the z-axis (also called the first direction) being perpendicular to the substrate 201 and the z-axis being perpendicular to the x-axis. The dimension of the b-end on the y-axis is greater than the dimension of the c-end on the y-axis, the y-axis (also called the second direction) being parallel to the substrate 201 and the y-axis being perpendicular to the x-axis. Along the x-axis from the a-end, the second portion 502b of the material layer 502 includes a d-end and an e-end, wherein, since the material 502 is an entire material layer and the material layer 502 includes the first portion and the second portion, the first portion 502a of the material layer 502 is continuous with the second portion 502b of the material layer 502, and the d-end of the second portion 502b of the material layer 502 coincides with the c-end of the first portion 212a of the material layer 502. Wherein the dimension of the d end on the z axis is the same as the dimension of the e end on the z axis, and the dimension of the d end on the y axis is the same as the dimension of the c end on the y axis.
Illustratively, the dimension of the first portion 502a of the material layer 502 in the y-axis is greater from the a-end along the x-axis than the dimension of the c-end in the y-axis, and thus the dimension of the first portion 502a of the material layer 502 in the y-axis is tapered. The dimensions of the second portion 502b, d-end of the material layer 502 in the y-axis are the same as the dimensions of the e-end in the y-axis, and thus the dimensions of the second portion 502b of the material layer 502 in the y-axis are constant. That is, the material layer 502 remains unchanged as it gradually decreases in size in the y-axis to a minimum value as it extends from the a-end along the x-axis.
In some embodiments, the dimension of the first portion 502a of the material layer 502 in the y-axis is gradually reduced, and the opening angle of the first portion 502a of the material layer 502 in the y-axis is equal to or greater than the rayleigh opening angle of the third light beam, where rayleigh Li Zhangjiao θ=λ/(pi×ω2) of the third light beam, where λ is the wavelength of the third light beam, and ω2 is the beam waist radius of the third light beam.
Wherein the dimension of the b end on the z axis is the same as the dimension of the c end on the z axis, the d end coincides with the c end, and the dimension of the d end on the z axis is the same as the dimension of the e end on the z axis. Thus, the dimensions of material layer 502 in the z-axis remain unchanged as material layer 502 extends along the x-axis.
In some embodiments, for example, when the first portion 502a of the material layer 502 is engineered, there may be a predetermined offset such that the dimension of the b-end in the z-axis is not exactly equal to the dimension of the c-end in the z-axis, and when the difference between the dimension of the b-end in the z-axis and the dimension of the c-end in the z-axis is less than or equal to a predetermined value of 4, the dimension of the b-end in the z-axis is also considered to be the same as the dimension of the c-end in the z-axis. The predetermined value 4 is determined by engineering errors, which are not limited by the embodiments of the present application. The difference between the two values is equal to or less than a preset value 4.
For example, as shown in fig. 7, the focusing structure 51 is specifically convex along the y-axis, and is coupled to the optical fiber 40 by the coupler 50 in the photonic integrated circuit 20, when the actual alignment accuracy between the core 41 of the optical fiber 40 and the photonic integrated circuit PIC20 becomes larger along the y-axis, the focusing structure 51 can focus the first light beam transmitted from the optical fiber 40 to the coupler 50 and then transmitted to the material layer 502, so that the packaging tolerance between the optical fiber 40 and the photonic integrated circuit PIC20 is improved.
In other embodiments, the focusing structure 51 is convex along the z-axis, and is coupled to the optical fiber 40 by the coupler 50 in the photonic integrated circuit 20, and when the actual alignment accuracy between the core 41 of the optical fiber 40 and the photonic integrated circuit PIC20 becomes larger along the z-axis, the focusing structure 51 can focus the first light beam transmitted from the optical fiber 40 to the coupler 50 and then transmitted to the material layer 502, so that the packaging tolerance between the optical fiber 40 and the photonic integrated circuit PIC20 is improved.
In still other embodiments, the focusing structure 51 is convex along the z-axis and convex along the y-axis, which means that the end surface of the focusing structure 51 near the core 41 of the optical fiber 40 is spherical, and is coupled with the optical fiber 40 by the coupler 50 in the photonic integrated circuit 20, when the actual alignment accuracy of the core 41 of the optical fiber 40 and the photonic integrated circuit PIC20 becomes larger along the z-axis or becomes larger along the y-axis, the focusing structure 51 can focus the first light beam transmitted from the optical fiber 40 to the coupler 50 and then to the material layer 502, so as to improve the packaging tolerance of the optical fiber 40 and the photonic integrated circuit PIC 20.
In some embodiments, referring to fig. 8, in comparison to the coupler 50 shown in fig. 7, in the coupler shown in fig. 8, the material layer 502 further includes a third portion 502c disposed at the a-end, and the focusing structure 51 is formed on the third portion 502c of the material layer 502. That is, the third portion 502c, the first portion 502a, and the second portion 502b are included in the overall material layer 502 along the x-axis from the a-end. The focusing structure 51 is formed on the third portion 502c of the material layer 502, and the focusing structure 51 includes a lens and a grating array, so that a lens may be formed on the third portion 502c of the material layer 502, an incident surface of the lens faces the optical fiber 40, and an incident surface of the lens is a convex surface; or may be fabricated in a third portion 502c of the material layer 502 in a grating array having an entrance face facing the optical fiber 40.
Illustratively, when a lens is fabricated in the third portion 502c of the material layer 502 such that the focusing structure 51 is fabricated in the third portion 502c of the material layer 502, the curvature of the incident surface of the lens is 100 degrees or less, and the chord length of the incident surface of the lens is 5 microns or more such that the focal length of the lens is less than 20 microns. The focal length of the lens is specifically equal to or less than a predetermined value 1, where the predetermined value 1 is F, f= (pi·ω1·ω2)/λ, where ω1 is a beam waist radius of the first light beam, ω2 is a beam waist radius of the third light beam, and λ is a wavelength of the first light beam. Illustratively, the radius of the entrance face of the lens is 20 microns or less. The size of the incident surface of the lens on the z axis is less than or equal to a preset value 5, wherein the preset value 5 is L, and L=lambda/(2*n); λ is the wavelength of the first light beam, and n is the refractive index of the material of the focusing structure 51, i.e. the refractive index of the material layer 502. Illustratively, when the material of the material layer 502 is silicon nitride, the refractive index of the silicon nitride material is 2, and when the wavelength of the first light beam is 700nm to 800nm, the size of the incident surface of the lens in the z-axis is about 200nm.
Illustratively, the dimension of the b-terminus in the z-axis is equal to or less than a predetermined value of 6; the predetermined value 6 is L, l=λ/(2*n); lambda is the wavelength of the first light beam and n is the refractive index of the material layer 502. That is, when the focusing structure 51, the spot-size converter 52, and the waveguide 53 are formed on the entire material layer 502, the size of the material layer 502 in the z-axis is not changed, and is determined by the wavelength of the first light beam and the refractive index of the material layer 502. Illustratively, the material in material layer 502 is silicon nitride, which has a refractive index of 2, and the dimension of the b-terminal in the z-axis is about 200nm when the wavelength of the first light beam is 700nm to 800 nm.
Illustratively, whether the focusing structure 51 is mounted on a sidewall of the photonic integrated circuit PIC20 or the focusing structure 51 is formed on a third portion of the material layer 502, for example, the focal length of the focusing structure 51 is a predetermined value 7, the dimension of the first portion 502a of the material layer 502 in the x-axis is greater than or equal to the predetermined value 7. This may allow the spot of the second beam focused by the focusing structure 51 to be focused to a minimum dimension in the y-axis of the first portion 502a of the material layer 502.
Illustratively, the focusing structure 51 shown in fig. 8 is formed on the third portion 502c of the material layer 502, and thus the material of the focusing structure 51 and the material of the material layer 502 are the same material. The materials of the material layer 502 include: silicon nitride (Si 3N 4), hafnium oxide (HfO 2), lithium niobate (LiNbO 3), aluminum nitride (AlN), aluminum oxide (Al 2O 3).
Illustratively, in the atomic molecular photophysical system 10 shown in fig. 1, when the focusing structure 51 is attached to the sidewall of the photonic integrated circuit PIC20, the focusing structure 51 is attached to the sidewall of the photonic integrated circuit PIC20 by a cured adhesive, the optical fiber 40 is fixedly connected to the focusing structure 51 attached to the sidewall of the photonic integrated circuit PIC20 by the cured adhesive, and the distance between the center line of the core 41 in the optical fiber 40 and the center line of the focusing structure 51 is less than or equal to a predetermined value 2, specifically, the center line of the focusing structure 51 and the center line of the core 41 in the optical fiber 40 need to be aligned as much as possible. The distance between the center line of the focusing structure 51 and the center line of the material layer 502 is less than or equal to a predetermined value 3, specifically, the center line of the focusing structure 51 and the center line of the material layer 502 need to be aligned as much as possible. When the focusing structure 51 is formed on the third portion of the material layer 502, the optical fiber 40 and the photonic integrated circuit PIC20 are fixedly connected by cured adhesive, and a distance between a center line of the core 41 in the optical fiber 40 and a center line of the focusing structure 51 is less than or equal to a predetermined value 2, specifically, the center line of the focusing structure 51 and the center line of the core 41 in the optical fiber 40 need to be aligned as much as possible.
In other embodiments, referring to fig. 9, based on the coupler 50 shown in fig. 8, the coupler 50 shown in fig. 9 further comprises a focusing structure 61, wherein the focusing structure 61 is disposed between the focusing structure 51 and the optical fiber 40; the focusing structures 61 and 51 are used to focus the first light beam received from the optical fiber 40 coupled to the coupler 50.
As shown in fig. 9, for example, it is also shown that the coupler 50 may include two focusing structures, a focusing structure 61 and a focusing structure 51, respectively.
Illustratively, the focusing structure 61 may be the focusing structure 51 shown in fig. 7, wherein the material of the focusing structure 61 includes polyimide, SU8 photoresist, wherein the polyimide or SU8 photoresist is a high refractive index composite material as well as an organic material. For example, polyimide or SU8 photoresist may be dropped on the sidewalls of photonic integrated circuit PIC20 to form focusing structure 61, where the end of focusing structure 61 near core 41 of optical fiber 40 is convex, and fig. 9 specifically illustrates focusing structure 61 as being convex along the y-axis, in some embodiments, focusing structure 61 may be convex along the z-axis, and in other embodiments, focusing structure 61 may be convex along the z-axis and convex along the y-axis (i.e., the end of focusing structure 61 near core 41 of optical fiber 40 is spherical).
The focusing structure 51 may be specifically the focusing structure 51 shown in fig. 8, and the material of the focusing structure 51 and the material of the material layer 502 are the same material. The materials of the material layer 502 include: silicon nitride (Si 3N 4), hafnium oxide (HfO 2), lithium niobate (LiNbO 3), aluminum nitride (AlN), aluminum oxide (Al 2O 3). The materials of the focusing structure 51 therefore include: silicon nitride (Si 3N 4), hafnium oxide (HfO 2), lithium niobate (LiNbO 3), aluminum nitride (AlN), aluminum oxide (Al 2O 3). The focusing structure 51 comprises a lens and a grating array, and thus may be fabricated in the third portion 502c of the material layer 502 as a lens with its entrance face facing the optical fiber 40 and its entrance face being convex; or may be fabricated in a third portion 502c of the material layer 502 in a grating array having an entrance face facing the optical fiber 40. Illustratively, when a lens is fabricated in the third portion 502c of the material layer 502 such that the focusing structure 51 is fabricated in the third portion 502c of the material layer 502, the curvature of the incident surface of the lens is 100 degrees or less, and the chord length of the incident surface of the lens is 5 microns or more such that the focal length of the lens is less than 20 microns.
For example, as shown in fig. 9, when the coupler 50 includes the focusing structure 61 and the focusing structure 51, the equivalent focal length of the focusing structure 51 and the focusing structure 61 is specifically less than or equal to a predetermined value 1, where the predetermined value 1 is F, f= (pi×ω1×ω2)/λ, where ω1 is a beam waist radius of the first light beam, ω2 is a beam waist radius of the third light beam, and λ is a wavelength of the first light beam.
In other embodiments, referring to fig. 10, embodiments of the present application provide another coupler 50, wherein the coupler 50 shown in fig. 10 further includes a material layer 503 extending in the light transmission direction, as compared to the coupler 50 shown in fig. 8. Wherein the material layer 503 is surrounded by the cladding layer 501, the material layer 503 is disposed on a side of the material layer 502 away from the substrate 201, and the material layer 503 is in contact with the material layer 502.
Referring to fig. 10, the light transmission direction of the photonic integrated circuit PIC20 is an x-axis, and the material layer 503 includes a first portion 503a and a second portion 503b along the x-axis from the a-end, where a projection of the first portion 503a of the material layer 503 onto the material layer 502 is located in the first portion 502a of the material layer 502, and a projection of the second portion 503b of the material layer 503 onto the material layer 502 overlaps with the second portion 502b of the material layer 502. The first portion 502a of the material layer 502 and the first portion 503a of the material layer 503 form the structure of the spot-size converter 52 shown in fig. 5, and the second portion 502b of the material layer 502 and the second portion 503b of the material layer 503 form the structure of the waveguide 53 shown in fig. 5. Illustratively, the first portion 502a of the material layer 502 and the first portion 503a of the material layer 503 are configured to change a spot of the second light beam, generate a third light beam, and output the third light beam; the second portion 502b of the material layer 502 and the second portion 503b of the material layer 503 are used for transmitting the third light beam.
Specifically, referring to FIG. 10, a first portion 503a of material layer 503 includes an f-terminal and a g-terminal along the x-axis from the a-terminal. The projection of the first portion 503a of the material layer 503 onto the material layer 502 is located within the first portion 502a of the material layer 502, specifically, the projection of the g-end onto the material layer 502 overlaps the c-end, and the projection of the f-end onto the material layer 502 is located between the b-end and the c-end. Wherein the dimension of the f end on the z axis is the same as the dimension of the g end on the z axis, and the dimension of the f end on the y axis is smaller than the dimension of the g end on the y axis. Along the x-axis from the a-axis, the second portion 503b of the material layer 503 includes an h-end and an i-end, wherein, since the material layer 503 is an entire material layer and the material layer 503 includes a first portion and a second portion, the first portion 503a of the material layer 503 and the second portion 503b of the material layer 503 are continuous, the h-end of the second portion 503b of the material layer 503 coincides with the g-end of the first portion 503a of the material layer 503, the dimension of the h-end in the z-axis is the same as the dimension of the i-end in the z-axis, and the dimension of the h-end in the y-axis is the same as the dimension of the i-end in the y-axis.
Illustratively, referring to FIG. 10, along the x-axis from the a-end, the first portion 502a of the material layer 502 includes a first subsection 502a1 and a second subsection 502a2, wherein the first portion 502a of the material layer 502 further includes a k-end positioned between the b-end and the c-end, the k-end being configured to space the first subsection 502a1 and the second subsection 502a2. More specifically, the first subsection 502a1 is a region of the first section 502a of the material layer 502 defined between the b-and k-ends and the second subsection 502a2 is a region of the first section 502a of the material layer 502 defined between the k-and c-ends. Wherein the dimension of the b end on the y axis is larger than the dimension of the c end on the y axis, specifically the dimension of the b end on the y axis is larger than the dimension of the k end on the y axis, the dimension of the first subsection 502a1 on the y axis is gradually reduced, the dimension of the k end on the y axis is the same as the dimension of the c end on the y axis, and the dimension of the second subsection 502a2 on the y axis is unchanged.
Illustratively, the projection of the f-side onto the material layer 502 is between the b-side and the c-side, and more specifically, the projection of the f-side onto the material layer 502 is between the b-side and the k-side, meaning that it extends from the a-side along the x-axis, and the beginning of the material layer 503 extends from the a-side along the x-axis when the dimension of the first subsection 502a1 in the y-axis is not reduced to a minimum. In some embodiments, the dimensions in the y-axis of the first portion 502a of the material layer 502 are: the beginning of material layer 503 extends from the a-end along the x-axis when half the sum of the dimension of the b-end on the y-axis and the dimension of the k-end on the y-axis.
Illustratively, the first portion 503a of the material layer 503 has a smaller dimension in the y-axis from the a-end along the x-axis than the g-end, and thus the first portion 503a of the material layer 503 has a progressively larger dimension in the y-axis. The dimensions of the second portion 503b, h-end of the material layer 503 in the y-axis are the same as the dimensions of the i-end in the y-axis, so that the dimensions of the second portion 503b of the material layer 503 in the y-axis are constant. That is, the dimension of the material layer 503 in the y-axis gradually increases to a maximum value and remains unchanged as it extends from the a-end along the x-axis.
Wherein the dimension of the f end on the z axis is the same as the dimension of the g end on the z axis, the g end coincides with the h end, and the dimension of the h end on the z axis is the same as the dimension of the i end on the z axis. Thus, the dimension of the material layer 503 in the z-axis remains unchanged as the material layer 503 extends along the x-axis.
In the coupler 50 shown in fig. 10, the first portion 502a of the material layer 502 and the first portion 503a of the material layer 503 are formed in the structure of the spot size converter 52, and the first portion 502a of the material layer 502 has a larger size on the y-axis at the end near the core 41 of the optical fiber 40, so that the spot size near the end face of the spot size converter 22 of the core 41 is larger, and the second light beam is easily received. And the first portion 502a of the material layer 502 gradually decreases in size in the y-axis as the first portion 502a of the material layer 502 extends along the x-axis. In addition, when the dimension of the first portion 502a of the material layer 502 in the y-axis is not reduced to a minimum value, the dimension of the first portion 503a of the material layer 503 in the y-axis is gradually increased, so that the second light beam can realize low-loss adiabatic transmission in the spot-changer 52 when the spot-changer 52 changes the spot of the second light beam to generate the third light beam.
In other embodiments, referring to fig. 11, embodiments of the present application provide another coupler 50, wherein the coupler 50 shown in fig. 11 further includes a material layer 503 and a material layer 504 extending in the light transmission direction, as compared to the coupler 50 shown in fig. 8. Wherein the material layer 503 is wrapped by the cladding layer 501, the material layer 503 is disposed on one side of the material layer 502 away from the substrate 201, and the cladding layer 501 is disposed between the material layer 502 and the material layer 503; the material layer 504 is surrounded by the cladding layer 501, the material layer 504 is arranged on the side of the material layer 502 close to the substrate 201, and the cladding layer 501 is arranged between the material layer 502 and the material layer 504.
Referring to fig. 11, the light transmission direction of the photonic integrated circuit PIC20 is the x-axis, and the material layer 503 includes a first portion 503a and a second portion 503b along the x-axis from the a-end, where a projection of the material layer 503 on the material layer 502 is located in the first portion 502a of the material layer 502. Along the x-axis from the a-terminus, the material layer 504 includes a first portion 504a and a second portion 504b, wherein a projection of the material layer 504 onto the material layer 502 is located within the first portion 502a of the material layer 502. The focusing structure 51, the first portion 503a of the material layer 503 and the first portion 504a of the material layer 504 form a first structure for focusing the first light beam received from the optical fiber 40 coupled to the coupler 50 and outputting a second light beam; the first portion 502a of the material layer 502, the second portion 503b of the material layer 503, and the second portion 504b of the material layer 504 form a structure of the spot-size converter 52 shown in fig. 5, which is used to change the spot size of the second light beam and output the third light beam. The second portion 502b of the material layer 502 forms a structure of a waveguide 53 as shown in fig. 5 for transmitting a third light beam.
Specifically, referring to FIG. 11, a first portion 503a of material layer 503 includes an f-terminal along the x-axis from the a-terminal. The f end is a light beam incident end, and an end surface of the f end is a convex surface, wherein an end surface of the first portion 503a of the material layer 503 on which the light beam exits is a plane, and the first portion 503a of the material layer 503 can implement focusing of the received light beam. Illustratively, the first portion 503a of the material layer 503 shown in fig. 11 is a lens structure, and the dimension of the first portion 503a of the material layer 503 in the x-axis may be the same as the dimension of the focusing structure 51 shown in fig. 11 (or fig. 8) in the x-axis; the dimension of the first portion 503a of the material layer 503 in the y-axis may be the same as the dimension of the focusing structure 51 in the y-axis shown in fig. 11 (or fig. 8); the dimension of the first portion 503a of the material layer 503 in the z-axis may be the same as the dimension of the focusing structure 51 in the z-axis shown in fig. 11 (or fig. 8).
Along the x-axis from the a-end, the second portion 503b of the material layer 503 includes a g-end and an h-end, wherein, since the material layer 503 is an entire material layer and the material layer 503 includes a first portion and a second portion, the first portion 503a of the material layer 503 and the second portion 503b of the material layer 503 are continuous, the g-end is used to space the first portion 503a of the material layer 503 and the second portion 503b of the material layer 503, and more specifically, the first portion 503a of the material layer 503 is a section of the material layer 503 defined between the f-end and the g-end, and the second portion 503b of the material layer 503 is a section of the material layer 503 defined between the g-end and the h-end. Wherein the dimension of the g-end on the z-axis is the same as the dimension of the h-end on the z-axis, and the dimension of the g-end on the y-axis is larger than the dimension of the h-end on the y-axis.
Illustratively, along the x-axis from the a-end, the second portion 503b of the material layer 503 includes a first sub-portion 503b1 and a second sub-portion 503b2, wherein the second portion 503b of the material layer 503 further includes a v-end, which is located between the g-end and the h-end, the v-end being configured to space the first sub-portion 503b1 and the second sub-portion 503b2. More specifically, the first subsection 503b1 is a region of the second section 503b of the material layer 503 defined between the g-end and the v-end and the second subsection 503b2 is a region of the second section 503b of the material layer 503 defined between the v-end and the h-end. Wherein the dimension of the g-end on the y-axis is larger than the dimension of the h-end on the y-axis, specifically the dimension of the g-end on the y-axis is larger than the dimension of the v-end on the y-axis, the dimension of the first subsection 503b1 on the y-axis is gradually reduced, the dimension of the v-end on the y-axis is the same as the dimension of the h-end on the y-axis, and the dimension of the second subsection 503b2 on the y-axis is unchanged. That is, the dimension of the second portion 503b of the material layer 503 in the y-axis is gradually reduced to a minimum value and then remains unchanged.
Specifically, referring to FIG. 11, a first portion 504a of the material layer 504 includes an i-terminus from an a-terminus along the x-axis. The end i is a light beam incident end, and an end face of the end i is a convex surface, wherein an end face of the first portion 504a of the material layer 504 where the light beam exits is a plane, and the first portion 504a of the material layer 504 can implement focusing of the received light beam. Illustratively, the first portion 504a of the material layer 504 shown in fig. 11 is a lens structure, and the first portion 504a of the material layer 504 may have the same dimension in the x-axis as the focusing structure 51 shown in fig. 11 (or fig. 8); the dimension of the first portion 504a of the material layer 504 in the y-axis may be the same as the dimension of the focusing structure 51 shown in fig. 11 (or fig. 8) in the y-axis; the dimension of the first portion 504a of the material layer 504 in the z-axis may be the same as the dimension of the focusing structure 51 in the z-axis shown in fig. 11 (or fig. 8).
Along the x-axis from the a-side, the second portion 504b of the material layer 504 includes a j-side and an m-side, wherein, since the material layer 504 is an entire material layer and the material layer 504 includes a first portion and a second portion, the first portion 504a of the material layer 504 and the second portion 504b of the material layer 504 are continuous, the j-side is used to space the first portion 504a of the material layer 504 and the second portion 504b of the material layer 504, and more specifically, the first portion 504a of the material layer 504 is a section of the material layer 504 defined between the i-side and the j-side, and the second portion 504b of the material layer 504 is a section of the material layer 504 defined between the j-side and the m-side. The size of the j end on the z axis is the same as that of the m end on the z axis, and the size of the j end on the y axis is larger than that of the m end on the y axis.
Illustratively, in some embodiments, the second portion 504b of the material layer 504 is the same shape as the second portion 503b of the material layer 503, wherein the second portion 503b of the material layer 503 remains unchanged after decreasing in size to a minimum in the y-axis.
In other embodiments, the projection of the material layer 504 on the material layer 503 overlaps the material layer 503, for example, the projection of the material layer 504 on the material layer 503 completely overlaps the material layer 503, or the size of the interval between the projection of the material layer 504 on the material layer 503 and the material layer 503 is less than or equal to a predetermined value 8, which is not limited by the embodiment of the present application.
In still other embodiments, material layer 504 is symmetrical with material layer 503 relative to the centerline of material layer 502 about the centerline of material layer 502 as an axis of symmetry. Wherein the distance between the material layer 502 and the material layer 503 has a dimension D in the z-axis, D is 100nm or more and 2 μm or less.
Illustratively, the first portion 502a of the material layer 502 may be tapered in size along the y-axis as it extends from the a-end along the x-axis, such as the schematic configuration of the first portion 502a of the material layer 502 shown in fig. 8; or the dimension of the first portion 502a of the material layer 502 in the y-axis may be tapered and then remain unchanged, for example, the schematic structure of the first portion 502a of the material layer 502 shown in fig. 10.
Illustratively, referring to fig. 11, in the coupler 50 shown in fig. 11, the material layer 503, the material layer 502, and the material layer 504 are arranged along the z-axis, wherein the focusing structure 51 may achieve focusing, the first portion 503a of the material layer 503 may achieve focusing, the first portion 504a of the material layer 504 may achieve focusing, and a distance between the focusing structure 51 and an end face of the optical fiber 40 near the photonic integrated circuit PIC20 is greater than a dimension of a distance between the first portion 503a of the material layer 503 and an end face of the optical fiber 40 near the photonic integrated circuit PIC20 in the x-axis; the distance between the focusing structure 51 and the end face of the optical fiber 40 close to the photonic integrated circuit PIC20 is larger in the x-axis than the distance between the first portion 504a of the material layer 504 and the end face of the optical fiber 40 close to the photonic integrated circuit PIC 20. That is, when the first light beam is received by the coupler 50, the focusing structure 51, the first portion 503a of the material layer 503, and the first portion 504a of the material layer 504 can also achieve focusing in the z-axis direction, so that most of the energy in the first light beam is received and focused, thereby again improving the coupling efficiency of the coupler 50.
In some embodiments, referring to fig. 12, the coupler 50 shown in fig. 12 further includes a material layer 505 and a material layer 506 extending in the light transmission direction on the basis of the coupler 50 shown in fig. 11. Wherein the material layer 505 is wrapped by the cladding layer 501, the material layer 505 is disposed on one side of the material layer 503 away from the material layer 502, and the cladding layer 501 is disposed between the material layer 503 and the material layer 505; the material layer 506 is surrounded by the cladding 501, the material layer 506 is arranged on the side of the material layer 504 remote from the material layer 502, and the cladding 501 is arranged between the material layer 504 and the material layer 505.
Wherein, referring to fig. 12, the light transmission direction of the photonic integrated circuit PIC20 is the x-axis, and the material layer 505 includes a first portion 505a and a second portion 505b along the x-axis from the a-end, wherein the projection of the material layer 505 on the material layer 503 overlaps the material layer 503. Along the x-axis from the a-end, the material layer 506 includes a first portion 506a and a second portion 506b, wherein a projection of the material layer 506 onto the material layer 504 overlaps the material layer 504. The focusing structure 51, the first portion 503a of the material layer 503, the first portion 504a of the material layer 504, the first portion 505a of the material layer 505 and the first portion 506a of the material layer 506 form a first structure for focusing a first light beam received from the optical fiber 40 coupled to the coupler 50, outputting a second light beam; the first portion 502a of the material layer 502, the second portion 503b of the material layer 503, the second portion 504b of the material layer 504, the second portion 505b of the material layer 505 and the second portion 506b of the material layer 506 form a structure of a spot size converter 52 as shown in fig. 5, for changing a spot size of the second light beam and outputting a third light beam. The second portion 502b of the material layer 502 forms a structure of a waveguide 53 as shown in fig. 5 for transmitting a third light beam.
Specifically, referring to fig. 12, a first portion 505a of the material layer 505 includes an n-terminal along the x-axis from the a-terminal. The n-end is a light beam incident end, and an end surface of the n-end is a convex surface, wherein an end surface of the light beam emitting end of the first portion 505a of the material layer 505 is a plane, and the first portion 505a of the material layer 505 can implement focusing of the received light beam. Illustratively, as shown in FIG. 12, the first portion 505a of the material layer 505 is a lens structure, and the first portion 505a of the material layer 505 may have the same dimensions in the x-axis as the focusing structure 51 shown in FIG. 12 (or FIG. 8); the dimension of the first portion 505a of the material layer 505 in the y-axis may be the same as the dimension of the focusing structure 51 shown in fig. 12 (or fig. 8) in the y-axis; the dimension of the first portion 505a of the material layer 505 in the z-axis may be the same as the dimension of the focusing structure 51 shown in fig. 12 (or fig. 8) in the z-axis.
Along the x-axis from the a-side, the second portion 505b of the material layer 505 includes an o-side and a p-side, wherein, since the material 505 is an entire material layer and the material layer 505 includes a first portion and a second portion, the first portion 505a of the material layer 505 and the second portion 505b of the material layer 505 are continuous, the o-side is used to space the first portion 505a of the material layer 505 and the second portion 505b of the material layer 505, and more specifically, the first portion 505a of the material layer 505 is a section of the material layer 505 defined between the n-side and the o-side, and the second portion 505b of the material layer 505 is a section of the material layer 505 defined between the o-side and the p-side. Wherein the dimension of the o-terminal on the z-axis is the same as the dimension of the p-terminal on the z-axis, and the dimension of the o-terminal on the y-axis is larger than the dimension of the p-terminal on the y-axis.
In some embodiments, the second portion 505b of the material layer 505 is the same shape as the second portion 503b of the material layer 503, wherein the second portion 505b of the material layer 505 is tapered in size in the y-axis and then remains unchanged.
In other embodiments, the projection of the material layer 505 on the material layer 503 overlaps the material layer 503, for example, the projection of the material layer 505 on the material layer 503 completely overlaps the material layer 503, or the size of the interval between the projection of the material layer 505 on the material layer 503 and the material layer 503 is less than or equal to a predetermined value 9, which is not limited by the embodiment of the present application.
Specifically, referring to FIG. 12, a first portion 506a of material layer 506 includes a q-terminus along the x-axis from the a-terminus. The q-end is a light beam incident end, and an end surface of the q-end is a convex surface, where an end surface of the light beam emitting end of the first portion 506a of the material layer 506 is a plane, and the first portion 506a of the material layer 506 may implement focusing of the received light beam. Illustratively, the first portion 506a of the material layer 506 shown in fig. 12 is a lens structure, and the dimension of the first portion 506a of the material layer 506 in the x-axis may be the same as the dimension of the focusing structure 51 shown in fig. 12 (or fig. 8) in the x-axis; the dimension of the first portion 506a of the material layer 506 in the y-axis may be the same as the dimension of the focusing structure 51 shown in fig. 12 (or fig. 8) in the y-axis; the dimension of the first portion 506a of the material layer 506 in the z-axis may be the same as the dimension of the focusing structure 51 in the z-axis shown in fig. 12 (or fig. 8).
Along the x-axis from the a-side, the second portion 506b of the material layer 506 includes an r-side and an s-side, wherein, since the material layer 506 is a whole material layer and the material layer 506 includes a first portion and a second portion, the first portion 506a of the material layer 506 and the second portion 506b of the material layer 506 are continuous, the r-side is used to space the first portion 506a of the material layer 506 and the second portion 506b of the material layer 506, and more specifically, the first portion 506a of the material layer 506 is a section of the material layer 506 defined between the q-side and the r-side, and the second portion 506b of the material layer 506 is a section of the material layer 506 defined between the r-side and the s-side. Wherein the dimension of the r end on the z axis is the same as the dimension of the s end on the z axis, and the dimension of the r end on the y axis is larger than the dimension of the s end on the y axis.
Illustratively, in some embodiments, the second portion 506b of the material layer 506 is the same shape as the second portion 504b of the material layer 504, wherein the second portion 504b of the material layer 504 is tapered in size in the y-axis and then remains unchanged.
In other embodiments, the projection of the material layer 506 onto the material layer 504 overlaps the material layer 504, for example, the projection of the material layer 506 onto the material layer 504 completely overlaps the material layer 504, or the dimension of the space between the projection of the material layer 506 onto the material layer 504 and the material layer 504 is less than or equal to a predetermined value 10, which is not limited by the embodiments of the present application.
In still other embodiments, material layer 505 is symmetrical with material layer 506 about the centerline of material layer 502 as an axis of symmetry, as compared to the centerline of material layer 502.
Illustratively, referring to fig. 12, in the coupler 50 shown in fig. 12, the material layers 505, 503, 502, 504, and 506 are arranged along the z-axis, the focusing structure 51 may achieve focusing, the first portion 503a of the material layer 503 may achieve focusing, the first portion 504a of the material layer 504 may achieve focusing, the first portion 505a of the material layer 505 may achieve focusing, and the first portion 506a of the material layer 506 may achieve focusing. In addition, the material layers 505, 503, 502, 504 and 506 are sequentially arranged along the z-axis, that is, when the coupler 50 receives the first light beam, the focusing structure 51, the first portion 503a of the material layer 503, the first portion 504a of the material layer 504, the first portion 505a of the material layer 505 and the first portion 506a of the material layer 506 may achieve a larger range of focusing in the z-axis direction, so as to again improve the coupling efficiency of the coupler 50.
Illustratively, in other embodiments, referring to fig. 13, the coupler 50 shown in fig. 13 further comprises, in comparison to the coupler 50 shown in fig. 8: is provided on the material layer 503 extending in the light transmission direction. Wherein the material layer 503 is surrounded by the cladding layer 501, the material layer 503 is disposed on a side of the material layer 502 remote from the substrate 201. A cladding layer 501 is provided between the material layer 503 and the material layer 502.
Referring to fig. 13, the light transmission direction of the photonic integrated circuit PIC20 is an x-axis, and the material layer 503 includes a first portion 503a and a second portion 503b along the x-axis from the a-end, where a projection of the first portion 503a of the material layer 503 onto the material layer 502 is located in the first portion 502a of the material layer 502, and a projection of the second portion 503b of the material layer 503 onto the material layer 502 overlaps with the second portion 502b of the material layer 502. The first portion 502a of the material layer 502 and the first portion 503a of the material layer 503 form the structure of the spot-size converter 52 shown in fig. 5, and the second portion 502b of the material layer 502 and the second portion 503b of the material layer 503 form the structure of the waveguide 53 shown in fig. 5. Illustratively, the first portion 502a of the material layer 502 and the first portion 503a of the material layer 503 are configured to change a spot of the second light beam, generate a third light beam, and output the third light beam; the second portion 502b of the material layer 502 and the second portion 503b of the material layer 503 are used for transmitting the third light beam.
Specifically, referring to FIG. 13, a first portion 503a of material layer 503 includes an f-terminal and a g-terminal along the x-axis from the a-terminal. The projection of the first portion 503a of the material layer 503 onto the material layer 502 is located within the first portion 502a of the material layer 502, specifically, the projection of the g-end onto the material layer 502 overlaps the c-end, and the projection of the f-end onto the material layer 502 is located between the b-end and the c-end. Wherein the dimension of the f-end on the z-axis is smaller than the dimension of the g-end on the z-axis, and the dimension of the f-end on the y-axis is the same as the dimension of the g-end on the y-axis. Along the x-axis from the a-axis, the second portion 503b of the material layer 503 includes an h-end and an i-end, wherein, since the material layer 503 is an entire material layer and the material layer 503 includes a first portion and a second portion, the first portion 503a of the material layer 503 and the second portion 503b of the material layer 503 are continuous, the h-end of the second portion 503b of the material layer 503 coincides with the g-end of the first portion 503a of the material layer 503, the dimension of the h-end in the z-axis is the same as the dimension of the i-end in the z-axis, and the dimension of the h-end in the y-axis is the same as the dimension of the i-end in the y-axis.
Illustratively, along the x-axis from the a-end, the first portion 502a of the material layer 502 includes a first sub-portion 502a1 and a second sub-portion 502a2, wherein the first portion 502a of the material layer 502 further includes a k-end, the k-end being located between the b-end and the c-end, the k-end being configured to space the first sub-portion 502a1 and the second sub-portion 502a2. More specifically, the first subsection 502a1 is a region of the first section 502a of the material layer 502 defined between the b-and k-ends and the second subsection 502a2 is a region of the first section 502a of the material layer 502 defined between the k-and c-ends. Wherein the dimension of the b end on the y axis is larger than the dimension of the c end on the y axis, specifically the dimension of the b end on the y axis is larger than the dimension of the k end on the y axis, the dimension of the first subsection 502a1 on the y axis is gradually reduced, the dimension of the k end on the y axis is the same as the dimension of the c end on the y axis, and the dimension of the second subsection 502a2 on the y axis is unchanged.
Illustratively, the projection of the f-side onto the material layer 502 is located between the b-side and the c-side, and more specifically, the projection of the f-side onto the material layer 502 overlaps the k-side, meaning that it extends from the a-side along the x-axis, and the beginning of the material layer 503 extends from the a-side along the x-axis when the dimension of the first subsection 502a1 in the y-axis is reduced to a minimum.
Illustratively, the dimension of the first portion 503a of the material layer 503 in the z-axis is smaller than the dimension of the g-end in the z-axis from the a-end along the x-axis, so that the dimension of the first portion 503a of the material layer 503 in the z-axis is gradually increased. The dimensions of the second portion 503b, h-end of the material layer 503 in the z-axis are the same as the dimensions of the i-end in the z-axis, so that the dimensions of the second portion 503b of the material layer 503 in the z-axis are constant. That is, the dimension of the material layer 503 in the z-axis gradually increases to a maximum value and remains unchanged as it extends from the a-end along the x-axis.
The size of the f end on the y axis is the same as the size of the g end on the y axis, the g end coincides with the h end, and the size of the h end on the y axis is the same as the size of the i end on the y axis. Thus, the dimension of the material layer 503 in the z-axis remains unchanged as the material layer 503 extends along the x-axis.
In the coupler 50 shown in fig. 13, the first portion 502a of the material layer 502 and the first portion 503a of the material layer 503 are formed in the structure of the spot size converter 52, and the first portion 502a of the material layer 502 has a larger size on the y-axis at the end near the core 41 of the optical fiber 40, so that the spot size near the end face of the spot size converter 22 of the core 41 is larger, and the second light beam is easily received. And the first portion 502a of the material layer 502 gradually decreases in size in the y-axis as the first portion 502a of the material layer 502 extends along the x-axis. In addition, as the dimension of the first portion 502a of the material layer 502 in the y-axis decreases to a minimum, the dimension of the first portion 503a of the material layer 503 in the z-axis gradually increases, so that the second beam can achieve low-loss adiabatic transfer in the spot-changer 52 as the spot-changer 52 changes the spot of the second beam to generate the third beam.
In other embodiments, referring to FIG. 14, embodiments of the present application provide another coupler 50, the coupler 50 comprising a focusing structure 51 and a cladding layer 501 disposed on a substrate 201; further comprising a material layer 502 extending in the light transmission direction, the material layer 502 being surrounded by the cladding layer 501, the a-end of the material layer 502 being directed towards the focusing structure 51; from the a-end along the light transmission direction, the material layer 502 includes a first portion 502a and a second portion 502b; a focusing structure 51 for focusing the first light beam received from the optical fiber 40 coupled with the coupler 50 and outputting a second light beam; a first portion 502a of the material layer 502 for changing a spot of the second light beam and outputting a third light beam; a second portion 502b of the material layer 502 is used for transmitting a third light beam.
Illustratively, referring to fig. 14, the focusing structure 51 may be attached to a sidewall of the photonic integrated circuit PIC 20. Wherein the optical fiber 40 is coupled to the sidewall, specifically, the incident surface of the focusing structure 51 faces the optical fiber 40, wherein the end surface of the focusing structure 51 near the core 41 of the optical fiber 40 is convex, fig. 14 specifically illustrates that the focusing structure 51 is convex along the z-axis and convex along the y-axis (that is, the end surface of the focusing structure 51 near the core 41 of the optical fiber 40 is denoted as a spherical surface), and in some embodiments, the focusing structure 51 may be convex along the y-axis, and in other embodiments, the focusing structure 51 may be convex along the z-axis. Illustratively, the a-end of the material layer 502 is in contact with the focusing structure 51, and the accuracy of the encapsulation of the core 41 of the optical fiber 40 with the coupler 50 in the photonic integrated circuit PIC20 is less than or equal to the rayleigh length of the first light beam transmitted in the optical fiber 40. Illustratively, the material of the focusing structure 51 includes polyimide, SU8 photoresist, wherein polyimide or SU8 photoresist is a high refractive index composite material as well as an organic material. Illustratively, polyimide or SU8 photoresist may be dropped on the sidewalls of photonic integrated circuit PIC20 to form focusing structure 51.
Specifically, referring to fig. 14, along the x-axis from the a-end, a first portion 502a of the material layer 502 includes a b-end and a c-end, wherein the b-end of the first portion 502a of the material layer 502 coincides with the a-end of the material layer 502. The dimension of the b-end in the z-axis is the same as the dimension of the c-end in the z-axis, the z-axis being perpendicular to the substrate 201 and the z-axis being perpendicular to the x-axis. The dimension of the b-end on the y-axis is smaller than the dimension of the c-end on the y-axis, the y-axis being parallel to the substrate 201 and the y-axis being perpendicular to the direction of the x-axis. Along the x-axis from the a-end, the second portion 502b of the material layer 502 includes a d-end and an e-end, wherein the d-end of the second portion 502b of the material layer 502 coincides with the c-end of the first portion 502a of the material layer 502. The dimension of the d-end in the z-axis is the same as the dimension of the e-end in the z-axis. The dimension of the d-end on the y-axis is the same as the dimension of the c-end on the y-axis.
Wherein the dimension of the b-end in the y-axis is smaller than the dimension of the c-end in the y-axis, the dimension of the first portion 502a of the material layer 502 in the y-axis is gradually increasing. The dimension of the d-end in the y-axis is the same as the dimension of the e-end in the y-axis, and the dimension of the second portion 502b of the material layer 502 in the y-axis is constant. That is, extending from the a-end along the x-axis, the dimension of the material layer 502 in the y-axis gradually increases to a maximum value and remains the same.
Wherein the dimension of the b end on the z axis is the same as the dimension of the c end on the z axis, the d end coincides with the c end, and the dimension of the d end on the z axis is the same as the dimension of the e end on the z axis. Thus, the dimension of material layer 502 in the z-axis remains unchanged at all times.
In the coupler 50 shown in fig. 14, the first portion 502a of the material layer 502 is formed in the structure of the spot size converter 52, and the first portion 502a of the material layer 502 has a larger size in the z-axis at the end near the core 41 of the optical fiber 40, so that the spot size near the end face of the spot size converter 52 of the core 41 is larger, and the second light beam output by the focusing structure 51 is easily received. And as the first portion 502a of the material layer 502 extends along the x-axis, the first portion 502a of the material layer 502 gradually increases in size in the y-axis so that the second beam may achieve low-loss adiabatic transfer in the spot-changer 52 as the spot-changer 52 changes the spot of the second beam to generate the third beam.
The focusing structure 51 in the coupler 50 shown in fig. 10 to 13 is exemplified by a third portion 502c formed in the material layer 502. Of course, in other embodiments, the focusing structure 51 in the coupler 50 shown in fig. 10 to 13 may also be attached to the side wall of the photonic integrated circuit PIC 20. Or in still other embodiments, the coupler 50 shown in fig. 10 to 13 includes a focusing structure 51 and a focusing structure 61, where the focusing structure 51 is fabricated on the third portion 502c of the material layer 502, and the focusing structure 61 is attached to a sidewall of the photonic integrated circuit PIC 20. The embodiments of the present application are not limited in this regard.
Although the application has been described in connection with specific features and embodiments thereof, it will be apparent that various modifications and combinations can be made without departing from the spirit and scope of the application. Accordingly, the specification and drawings are merely exemplary illustrations of the present application as defined in the appended claims and are considered to cover any and all modifications, variations, combinations, or equivalents that fall within the scope of the application. It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims (23)

1. A coupler, comprising:
A first focusing structure and a cladding layer disposed on the substrate;
A first material layer extending in a light transmission direction, the first material layer being surrounded by the cladding layer, a first end of the first material layer being oriented towards the first focusing structure; from the first end along the light transmission direction, the first material layer includes a first portion and a second portion;
the first focusing structure is used for focusing the first light beam received from the optical fiber coupled with the coupler and outputting a second light beam;
A first portion of the first material layer for changing a spot of the second light beam, outputting a third light beam;
a second portion of the first material layer is configured to transmit the third light beam.
2. The coupler of claim 1, wherein the focal length of the first focusing structure is equal to or less than a first predetermined value, the first predetermined value being F, f= (pi ω1 ω2)/λ;
Wherein ω1 is the beam waist radius of the first light beam, ω2 is the beam waist radius of the third light beam, and λ is the wavelength of the first light beam.
3. The coupler according to claim 1 or 2, characterized in that the coupler further comprises: a second material layer extending in the light transmission direction;
The second material layer is wrapped by the cladding layer, and the second material layer is arranged on one side of the first material layer away from the substrate; from the first end along the light transmission direction, the second material layer includes a first portion and a second portion;
Wherein a projection of a first portion of the second material layer onto the first material layer is located within the first portion of the first material layer; a projection of a second portion of the second material layer onto the first material layer overlaps the second portion of the first material layer;
A first part of the first material layer and a first part of the second material layer form a first structure, and the first structure is used for changing the spot of the second light beam and outputting the third light beam;
the second portion of the first material layer and the second portion of the second material layer form a second structure for transmitting the third light beam.
4. The coupler according to claim 1 or 2, characterized in that the coupler further comprises: a second material layer and a third material layer extending along the light transmission direction;
The second material layer is wrapped by the cladding layer, the second material layer is arranged on one side of the first material layer away from the substrate, and the cladding layer is arranged between the first material layer and the second material layer; from the first end along the light transmission direction, the second material layer includes a first portion and a second portion;
wherein a projection of the second material layer onto the first material layer is located within a first portion of the first material layer;
The third material layer is wrapped by the cladding layer, the third material layer is arranged on one side of the first material layer, which is close to the substrate, and the cladding layer is arranged between the first material layer and the third material layer; from the first end along the light transmission direction, the third material layer includes a first portion and a second portion;
Wherein a projection of the third material layer onto the first material layer is located within a first portion of the first material layer;
the first focusing structure, the first portion of the second material layer, and the first portion of the third material layer form a first structure for focusing the first light beam received from the optical fiber coupled to the coupler, outputting the second light beam;
The first portion of the first material layer, the second portion of the second material layer, and the second portion of the third material layer form a second structure for changing a spot of the second light beam and outputting the third light beam.
5. A coupler according to claim 3, wherein the cladding is provided between the first material layer and the second material layer.
6. The coupler of claim 4, wherein the coupler further comprises: a fourth material layer and a fifth material layer extending along the light transmission direction;
The fourth material layer is wrapped by the cladding layer, the fourth material layer is arranged on one side, far away from the first material layer, of the second material layer, and the cladding layer is arranged between the fourth material layer and the second material layer; from the first end along the light transmission direction, the fourth material layer includes a first portion and a second portion;
Wherein a projection of the fourth material layer onto the second material layer overlaps the second material layer;
The fifth material layer is wrapped by the cladding layer, the fifth material layer is arranged on one side, far away from the first material layer, of the third material layer, and the cladding layer is arranged between the fifth material layer and the third material layer; from the first end along the light transmission direction, the fifth layer of material comprises a first portion and a second portion;
wherein a projection of the fifth material layer onto the third material layer overlaps the third material layer;
The first focusing structure, the first portion of the second material layer, the first portion of the third material layer, the first portion of the fourth material layer, and the first portion of the fifth material layer form the first structure;
The first portion of the first material layer, the second portion of the second material layer, the second portion of the third material layer, the second portion of the fourth material layer, and the second portion of the fifth material layer form the second structure.
7. A coupler according to claim 1 or 2, characterized in that,
A first portion of the first material layer includes a second end and a third end along the light transmission direction from the first end, the second end having a dimension in a first direction that is the same as a dimension of the third end in the first direction, the second end having a dimension in a second direction that is greater than a dimension of the third end in the second direction; wherein the first direction is perpendicular to the substrate, the second direction is parallel to the substrate and perpendicular to the light transmission direction;
the second portion of the first material layer includes a fourth end and a fifth end along the light transmission direction from the first end, the fourth end having the same dimension in the first direction as the fifth end, the fourth end having the same dimension in the second direction as the fifth end.
8. The coupler of claim 3, wherein the coupler comprises,
A first portion of the first material layer includes a second end and a third end along the light transmission direction from the first end, the second end having a dimension in a first direction that is the same as a dimension of the third end in the first direction, the second end having a dimension in a second direction that is greater than a dimension of the third end in the second direction; wherein the first direction is perpendicular to the substrate, the second direction is parallel to the substrate and perpendicular to the light transmission direction;
The second portion of the first material layer includes a fourth end and a fifth end along the light transmission direction from the first end, the fourth end having the same dimension in the first direction as the fifth end, the fourth end having the same dimension in the second direction as the fifth end;
A first portion of the second material layer along the light transmission direction from the first end includes a sixth end and a seventh end, the sixth end having the same dimension in the first direction as the seventh end, the sixth end having a smaller dimension in the second direction than the seventh end;
The second portion of the second material layer includes an eighth end and a ninth end from the first end in the light transmission direction, the eighth end having the same dimension in the first direction as the ninth end, the eighth end having the same dimension in the second direction as the ninth end.
9. A coupler according to claim 4 or 6, characterized in that,
A first portion of the first material layer includes a second end and a third end along the light transmission direction from the first end, the second end having a dimension in a first direction that is the same as a dimension of the third end in the first direction, the second end having a dimension in a second direction that is greater than a dimension of the third end in the second direction; wherein the first direction is perpendicular to the substrate, the second direction is parallel to the substrate and perpendicular to the light transmission direction;
The second portion of the first material layer includes a fourth end and a fifth end along the light transmission direction from the first end, the fourth end having the same dimension in the first direction as the fifth end, the fourth end having the same dimension in the second direction as the fifth end;
The first part of the second material layer comprises a sixth end along the light transmission direction from the first end, the sixth end is a light beam incident end, and the end face of the sixth end is a convex surface;
A second portion of the second material layer along the light transmission direction from the first end includes a seventh end and an eighth end, the seventh end having a dimension in the first direction that is the same as a dimension of the eighth end in the first direction, the seventh end having a dimension in the second direction that is greater than the dimension of the eighth end in the second direction;
The first part of the third material layer comprises a ninth end from the first end along the light transmission direction, the ninth end is a light beam incident end, and the end face of the ninth end is a convex surface;
The second portion of the third material layer includes a tenth end and a tenth end from the first end in the light transmission direction, the tenth end having a dimension in the first direction that is the same as a dimension of the eleventh end in the first direction, the tenth end having a dimension in the second direction that is greater than the dimension of the eleventh end in the second direction.
10. The coupler according to claim 5, wherein,
A first portion of the first material layer includes a second end and a third end along the light transmission direction from the first end, the second end having a dimension in a first direction that is the same as a dimension of the third end in the first direction, the second end having a dimension in a second direction that is greater than a dimension of the third end in the second direction; wherein the first direction is perpendicular to the substrate, the second direction is parallel to the substrate and perpendicular to the light transmission direction;
The second portion of the first material layer includes a fourth end and a fifth end along the light transmission direction from the first end, the fourth end having the same dimension in the first direction as the fifth end, the fourth end having the same dimension in the second direction as the fifth end;
a first portion of the second material layer includes a sixth end and a seventh end along the light transmission direction from the first end, the sixth end having a dimension in the first direction that is less than a dimension of the seventh end in the first direction, the sixth end having a dimension in the second direction that is the same as the dimension of the seventh end in the second direction;
The second portion of the second material layer includes an eighth end and a ninth end from the first end in the light transmission direction, the eighth end having the same dimension in the first direction as the ninth end, the eighth end having the same dimension in the second direction as the ninth end.
11. A coupler according to claim 1 or 2, characterized in that,
A first portion of the first material layer includes a second end and a third end along the light transmission direction from the first end, the second end having a dimension in a first direction that is the same as a dimension of the third end in the first direction, the second end having a dimension in a second direction that is less than the dimension of the third end in the second direction; wherein the first direction is perpendicular to the substrate, the second direction is parallel to the substrate and perpendicular to the light transmission direction;
the second portion of the first material layer includes a fourth end and a fifth end along the light transmission direction from the first end, the fourth end having the same dimension in the first direction as the fifth end, the fourth end having the same dimension in the second direction as the fifth end.
12. The coupler according to any one of claims 1 to 10, wherein,
The first material layer further comprises a third part arranged at the first end, and the first focusing structure is manufactured on the third part of the first material layer.
13. The coupler of claim 12, wherein the first focusing structure comprises a lens and a grating array; the incident surface of the lens is a convex surface.
14. The coupler of claim 13, wherein the curvature of the entrance face of the lens is 100 degrees or less and the chord length of the entrance face of the lens is 5 microns or more.
15. The coupler of claim 14, wherein a dimension of an incident face of the lens in a first direction, the first direction being perpendicular to the substrate, is less than or equal to a second predetermined value;
The second predetermined value is L, l=λ/(2*n);
the λ is a wavelength of the first light beam, and the n is a refractive index of a material of the first focusing structure.
16. The coupler of claim 12, wherein the coupler comprises a plurality of coupling elements,
The coupler further includes a second focusing structure disposed between the first focusing structure and the optical fiber; the second focusing structure and the first focusing structure are configured to focus a first light beam received from an optical fiber coupled to the coupler.
17. The coupler of claim 16, wherein an equivalent focal length of the second focusing structure and the first focusing structure is less than or equal to a third predetermined value, the third predetermined value being F, f= (pi ω1 ω2)/λ;
Wherein ω1 is the beam waist radius of the first light beam, ω2 is the beam waist radius of the third light beam, and λ is the wavelength of the first light beam.
18. The coupler according to any one of claims 7-10, wherein the second end has a dimension in the first direction that is equal to or less than a fourth predetermined value;
the fourth predetermined value is L, l=λ/(2*n);
the lambda is the wavelength of the first light beam and the n is the refractive index of the material of the first material layer.
19. The coupler of claim 2, wherein a focal length of the first focusing structure is a fifth predetermined value, and a dimension of the first portion of the first material layer in the light transmission direction is greater than or equal to the fifth predetermined value.
20. A photonic integrated circuit, comprising: a substrate and a coupler as claimed in any one of claims 1 to 19 disposed on the substrate.
21. An atomic molecular photophysical system comprising: a light source, an optical fiber, and the photonic integrated circuit of claim 20;
The light source is used for generating a light beam and transmitting the light beam to the photonic integrated circuit through the optical fiber.
22. The atomic molecular photophysical system of claim 21, wherein the optical fiber is fixedly connected to the photonic integrated circuit by a cured glue.
23. An atomic molecular photophysical system according to claim 21 or 22, wherein the distance between the centre line of the core of the optical fiber and the centre line of the focusing structure in the photonic integrated circuit is less than or equal to a sixth predetermined value.
CN202211352008.5A 2022-10-31 2022-10-31 Coupler, photonic integrated circuit and atomic molecular photophysical system Pending CN117950111A (en)

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CN202211352008.5A CN117950111A (en) 2022-10-31 2022-10-31 Coupler, photonic integrated circuit and atomic molecular photophysical system

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Application Number Priority Date Filing Date Title
CN202211352008.5A CN117950111A (en) 2022-10-31 2022-10-31 Coupler, photonic integrated circuit and atomic molecular photophysical system

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