CN110389407B - Optical antenna, phased array laser radar and preparation method of optical antenna - Google Patents
Optical antenna, phased array laser radar and preparation method of optical antenna Download PDFInfo
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- 230000003287 optical effect Effects 0.000 title claims abstract description 119
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/122—Basic optical elements, e.g. light-guiding paths
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/13—Integrated optical circuits characterised by the manufacturing method
Abstract
The invention provides an optical antenna, a phased array laser radar and a preparation method of the optical antenna. The optical antenna includes: the device comprises an SOI substrate, a waveguide structure layer, a spacing layer, a grating structure layer and a protective layer; the SOI substrate includes: a bottom silicon layer, a buried oxide layer and a top silicon layer; forming a waveguide structure layer on a top silicon layer of the SOI substrate, and sequentially arranging a spacing layer, a grating structure layer and a protective layer above the waveguide structure layer; because the difference value between the refractive index of the grating structure layer and the refractive indexes of the spacing layer and the protective layer is larger than the preset threshold value, and the refractive index of the grating structure layer is higher than the refractive indexes of the spacing layer and the protective layer, the grating structure layer has high refractive index contrast, so that when light waves are diffracted on the waveguide structure layer, the diffraction in the direction of the SOI substrate can be eliminated, the light waves can be successfully emitted upwards, high radiation efficiency is obtained, and the utilization rate of the optical antenna is greatly improved.
Description
Technical Field
The embodiment of the invention relates to the technical field of radars, in particular to an optical antenna, a phased array laser radar and a preparation method of the optical antenna.
Background
The concept of phased array lidar has been proposed for a long time, and various designs are being developed. The basic modules of the optical antenna module are mature, such as a light source module, a beam splitting module, a phase modulation module and the like, but in the optical antenna module, how to efficiently lead out the phase-modulated light of each waveguide from a photonic integrated circuit is still a great challenge. This is because the refractive index of the waveguide is much greater than that of air, and it is very difficult to couple light from the waveguide into free space, so that the radiation efficiency of the optical antenna is extremely low, which seriously affects its utilization rate.
At present, the optical antennas for the phased array laser radar are internationally mainly divided into a metal dipole type optical antenna and a non-metal optical antenna, wherein the non-metal optical antenna is mainly a grating type optical antenna. With the development of integrated optics, the grating optical antenna becomes the most effective coupling method for photonic integration due to the advantages of simple process, compatibility with the CMOS process, and the like.
However, in the conventional grating type optical antenna, the grating is not specially designed, and a conventional grating is adopted, so that light coupled out from the grating on each waveguide is seriously scattered, the radiation efficiency is extremely low, and the energy utilization rate of the optical antenna is extremely low.
Disclosure of Invention
The embodiment of the invention provides an optical antenna, a phased array laser radar and a preparation method of the optical antenna, and solves the technical problems that light coupled from a grating to the outside on each waveguide is seriously scattered and the radiation efficiency is extremely low due to the fact that a conventional grating is adopted in a grating type optical antenna in the prior art, and further the energy utilization rate of the optical antenna is extremely low.
In a first aspect, an embodiment of the present invention provides an optical antenna, including: the device comprises an SOI substrate, a waveguide structure layer, a spacing layer, a grating structure layer and a protective layer;
the SOI substrate includes: a bottom silicon layer, a buried oxide layer and a top silicon layer;
forming the waveguide structure layer on the top silicon layer of the SOI substrate, and sequentially arranging a spacing layer, a grating structure layer and a protective layer above the waveguide structure layer;
the difference between the refractive index of the grating structure layer and the refractive indexes of the spacing layer and the protective layer is larger than a preset threshold value, and the refractive index of the grating structure layer is higher than the refractive indexes of the spacing layer and the protective layer.
Further, as in the optical antenna described above, the buried oxide layer is located intermediate the bottom silicon layer and the top silicon layer.
Further, as the optical antenna, the waveguide structure layer includes: a strip waveguide array, a spot-size conversion structure and a wide slab waveguide;
the strip waveguide array and the wide slab waveguide are connected through the spot-size conversion structure.
Further, as for the optical antenna, the spot-size conversion structure is a trapezoid structure or a trapezoid-like structure with a curved oblique side, and one side of the short bottom side of the spot-size conversion structure is close to the strip waveguide array.
Further, as in the optical antenna described above, the grating structure layer is located completely above the wide slab waveguide.
Further, as for the optical antenna, the grating period in the grating structure layer is matched with the effective refractive index and the operating wavelength of the wide slab waveguide, and the grating thickness and the duty cycle in the grating structure layer satisfy the condition of emitting light upwards in the main lobe.
In a second aspect, embodiments of the present invention provide a phased array lidar including an optical antenna as claimed in any preceding claim.
Further, as for the phased array lidar, the etching depth of the strip waveguide array in the optical antenna is consistent with the thickness of the front-end device connected with the optical antenna.
In a third aspect, an embodiment of the present invention provides a method for preparing an optical antenna as described in any one of the above, including:
obtaining an SOI substrate;
etching the top silicon layer of the SOI substrate to form a waveguide structure layer;
depositing a spacer layer over the waveguide structure layer;
depositing a grating material layer above the spacing layer, and etching the grating material layer to form a grating structure layer;
growing a protective layer above the grating structure layer;
the difference between the refractive index of the grating structure layer and the refractive indexes of the spacing layer and the protective layer are both larger than a preset threshold value, and the refractive index of the grating structure layer is higher than the refractive indexes of the spacing layer and the protective layer.
Further, the method for manufacturing an optical antenna as described above, before depositing the grating material layer over the spacer layer, further includes:
setting a grating period in the grating structure layer according to a light wave band emitted by the optical antenna, so that the grating period is matched with the effective refractive index and the working wavelength of the wide slab waveguide;
and calculating the grating thickness and the duty ratio in the grating structure layer according to the condition that the main lobe emits light upwards.
The embodiment of the invention provides an optical antenna, a phased array laser radar and a preparation method of the optical antenna, wherein the optical antenna comprises the following components: the device comprises an SOI substrate, a waveguide structure layer, a spacing layer, a grating structure layer and a protective layer; the SOI substrate includes: a bottom silicon layer, a buried oxide layer and a top silicon layer; forming the waveguide structure layer on the top silicon layer of the SOI substrate, and sequentially arranging a spacing layer, a grating structure layer and a protective layer above the waveguide structure layer; the difference between the refractive index of the grating structure layer and the refractive indexes of the spacing layer and the protective layer is larger than a preset threshold value, and the refractive index of the grating structure layer is higher than the refractive indexes of the spacing layer and the protective layer. Because the spacing layer and the protective layer have low refractive indexes, the grating structure layer has a high refractive index, and the difference values of the refractive indexes of the grating structure layer and the refractive indexes of the spacing layer and the protective layer are larger than a preset threshold value, the grating structure layer has high refractive index contrast, so that when the waveguide structure layer diffracts, the diffraction in the direction of the SOI substrate can be eliminated, and the light wave can be successfully emitted upwards, thereby obtaining high radiation efficiency and further greatly improving the utilization rate of the optical antenna.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an optical antenna according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an optical antenna according to a second embodiment of the present invention;
fig. 3 is a schematic structural diagram of an SOI substrate in an optical antenna according to a second embodiment of the present invention;
fig. 4 is a schematic cross-sectional structure diagram of an optical antenna according to a second embodiment of the present invention after a waveguide structure layer is formed by etching a silicon layer on a top of an SOI substrate;
fig. 5 is a schematic top view of an optical antenna according to a second embodiment of the present invention, after a waveguide structure layer is formed by etching a silicon layer on a top of an SOI substrate;
fig. 6 is a schematic cross-sectional view of an optical antenna according to a second embodiment of the present invention after a spacer layer is deposited on the waveguide structure layer;
fig. 7 is a schematic top view of an optical antenna according to a second embodiment of the present invention after a spacer layer is deposited on the waveguide structure layer;
fig. 8 is a schematic cross-sectional structure diagram of the optical antenna according to the second embodiment of the present invention after depositing a grating material on the spacer layer and etching a grating;
fig. 9 is a schematic top view of the optical antenna according to the second embodiment of the present invention, after depositing a grating material on the spacer layer and etching a grating;
fig. 10 is a flowchart of a method for manufacturing an optical antenna according to a fourth embodiment of the present invention;
fig. 11 is a flowchart of a method for manufacturing an optical antenna according to a fifth embodiment of the present invention.
Reference numerals:
11-bottom silicon layer 12-buried oxide layer 13-top silicon layer 2-waveguide structure layer 21-strip waveguide array 22-spot-size conversion structure 23-wide slab waveguide 3-spacing layer 4-grating structure layer 5-protective layer
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Optical antennas are used to receive or transmit light waves and may be used in many optical systems. Such as a phased array lidar. Since the wavelength bands of light waves are very different, it is impossible to use all light waves with one optical antenna, and even if the same scheme can be used, the parameters thereof need to be changed correspondingly according to the wavelength bands of light waves processed by the optical antenna, and for convenience of expression, in each embodiment of the present invention, the wavelength band of light waves is 1.5 to 1.6 μm for example.
Fig. 1 is a schematic structural diagram of an optical antenna according to an embodiment of the present invention, and as shown in fig. 1, the optical antenna according to the embodiment includes: SOI substrate, waveguide structure layer 2, spacing layer 3, grating structure layer 4 and protective layer 5.
Wherein the SOI substrate includes: a bottom silicon layer 11, a buried oxide layer 12 and a top silicon layer 13.
Specifically, in the present embodiment, the waveguide structure layer 2 is formed on the top silicon layer 13 of the SOI substrate, and the spacer layer 3, the grating structure layer 4 and the protective layer 5 are sequentially disposed above the waveguide structure layer 2.
The difference between the refractive index of the grating structure layer 4 and the refractive indexes of the spacing layer 3 and the protective layer 5 is greater than a preset threshold, and the refractive index of the grating structure layer 4 is higher than the refractive indexes of the spacing layer 3 and the protective layer 5.
In the present embodiment, the SOI substrate is collectively referred to as a silicon-on-insulator substrate. The SOI substrate includes: a bottom silicon layer 11, a buried oxide layer 12 and a top silicon layer 13. Wherein a buried oxide layer 12 is located intermediate the bottom silicon layer 11 and the top silicon layer 13. Specifically, in this embodiment, the material and thickness of each layer of the SOI substrate may be customized according to different requirements, and the SOI substrate of the conventional standard CMOS process may also be used.
In the present embodiment, the waveguide structure layer 2 may be formed by etching the top silicon layer 13 of the SOI substrate. The waveguide structure layer 2 includes at least: the strip waveguide array may further include a spot-size conversion structure, a wide slab waveguide, and the like, which is not limited in this embodiment.
In the present embodiment, the spacer layer 3 may be formed above the waveguide structure layer 2 by deposition, the spacer layer 3 has a low refractive index, and the material for preparing the spacer layer 3 may be silicon dioxide.
In this embodiment, a grating material layer may be formed over the spacer layer 3 by a deposition method, and a grating structure layer 4 may be formed over the spacer layer 3 by an electron beam exposure or a step lithography method in combination with an ICP etching method. The grating material layer has a high refractive index, and may be a polysilicon layer.
In the present embodiment, a protective layer 5 may be formed over the grating structure layer 4 by growing, the protective layer 5 has a low refractive index, and the material of the protective layer 5 may be silicon dioxide.
In the present embodiment, the spacer layer 3 and the protection layer 5 have low refractive indexes, and the grating structure layer 4 has a high refractive index, which is relatively speaking, that is, the refractive index of the grating structure layer 4 is higher than the refractive indexes of the spacer layer 3 and the protection layer 5, in order to make the grating structure layer have high refractive index contrast, the difference between the refractive index of the grating structure layer 4 and the refractive indexes of the spacer layer 3 and the protection layer 5 is larger than a preset threshold, and the preset threshold is obtained through a plurality of tests.
The preset threshold value is related to the transmission wavelength of light, the material of a grating structure layer, the material of a spacing layer and the material of a protective layer, and the preset threshold value is usually 0.5-2.5 in an SOI substrate.
The optical antenna provided by the embodiment comprises: the structure comprises an SOI substrate, a waveguide structure layer 2, a spacing layer 3, a grating structure layer 4 and a protective layer 5; the SOI substrate includes: the structure comprises a bottom silicon layer 11, a buried oxide layer 12 and a top silicon layer 13, wherein a waveguide structure layer 2 is formed on the top silicon layer 13 of the SOI substrate, and a spacing layer 3, a grating structure layer 4 and a protective layer 5 are sequentially arranged above the waveguide structure layer 2; the difference between the refractive index of the grating structure layer 4 and the refractive indexes of the spacing layer 3 and the protective layer 5 is greater than a preset threshold. Because the spacing layer 3 and the protective layer 5 have low refractive indexes, the grating structure layer 4 has a high refractive index, and the difference values between the refractive index of the grating structure layer 4 and the refractive indexes of the spacing layer 3 and the protective layer 5 are both larger than a preset threshold value, the grating structure layer 4 has high refractive index contrast, so that when the waveguide structure layer 2 diffracts, the diffraction in the direction of the SOI substrate can be eliminated, and the light waves can be successfully emitted upwards, thereby obtaining high radiation efficiency and further greatly improving the utilization rate of the optical antenna.
Fig. 2 is a schematic structural diagram of an optical antenna according to a second embodiment of the present invention, and as shown in fig. 2, the optical antenna according to the present embodiment further includes the following features based on the optical antenna according to the first embodiment of the present invention.
Further, fig. 3 is a schematic structural diagram of an SOI substrate in an optical antenna according to a second embodiment of the present invention, as shown in fig. 3, in this embodiment, a buried oxide layer 12 in the SOI substrate of the optical antenna is located between a bottom silicon layer 11 and a top silicon layer 13.
Optionally, in this embodiment, an SOI substrate of a conventional standard CMOS process is selected, wherein the material of the bottom silicon layer 11 is silicon and has a thickness of 500-600 μm, the material of the buried oxide layer 12 is silicon dioxide and has a thickness of 2 μm, and the material of the top silicon layer 13 is silicon and has a thickness of 220 nm.
Further, fig. 4 is a schematic cross-sectional structure diagram after a waveguide structure layer is formed by etching a silicon layer on the top of the SOI substrate in the optical antenna provided by the second embodiment of the present invention, and fig. 5 is a schematic top-view structure diagram after a waveguide structure layer is formed by etching a silicon layer on the top of the SOI substrate in the optical antenna provided by the second embodiment of the present invention. In fig. 4, the top silicon layer 13 is not marked in fig. 4 since the top silicon layer of the SOI substrate is fully etched to form the waveguide structure layer. For the same reason, the top silicon layer 13 is not labeled in fig. 6 and 8 either, and as shown in fig. 4 and 5, in the present embodiment, the waveguide structure layer 2 includes: a strip waveguide array 21, a spot-size conversion structure 22 and a wide slab waveguide 23.
The strip waveguide array 21 and the wide slab waveguide 23 are connected by a spot-size conversion structure 22.
Specifically, in the present embodiment, each of the strip waveguides in the strip waveguide array 21 has a uniform size and is horizontally distributed. Each strip waveguide is connected with the wide slab waveguide 23 through the spot-size conversion structure 22, so that the light waves are well transferred from each strip waveguide to the wide slab waveguide 23, and energy loss caused by mismatching of front and rear waveguide spots is reduced.
Alternatively, the curve of the hypotenuse of the trapezoid-like structure in the spot-size converting structure 22 may be hyperbolic, or sinusoidal or other curve.
Preferably, in the present embodiment, the spot size conversion structure 22 is a trapezoid structure or a trapezoid-like structure, and a short bottom side of the spot size conversion structure 22 is close to the slab waveguide array 21.
In this embodiment, the speckle conversion structure 22 is a trapezoid structure or a trapezoid-like structure, so that the light waves can be more smoothly transited from each strip waveguide to the wide slab waveguide 23, and energy loss caused by mismatching of front and rear waveguide speckles is further reduced.
The longer the length of the spot size conversion structure 22 of the trapezoid structure or the trapezoid-like structure is, the more smoothly the spot size is transited from the slab waveguide array 21 to the wide slab waveguide 23, so that the length of the spot size conversion structure is larger than 15 μm in this embodiment.
Further, in the present embodiment, in order to make the mode input into the spot size conversion structure 22 by the slab waveguide array 21 match the mode of the rear-end wide slab waveguide 23 as much as possible, the output ends of the spot size conversion structure 22 are closely connected without a space. The output width of the spot-size converting structure 22 is determined by the waveguide pitch, and the output width of the spot-size converter in this embodiment is 0.5-5 μm.
In the present embodiment, since the refractive index of silicon for the 1.5 to 1.6 μm wavelength band is about 3.47, and the diffraction limit of the strip waveguide array 21 is considered, and the minimum waveguide width of the strip waveguide array 21 needs to be larger than the effective half wavelength of the propagating mode in the strip waveguide array 21, the waveguide width of the strip waveguide array 21 of the optical antenna is set to be 400 to 600 nm. Because the adjacent spacing of the strip waveguide arrays 21 directly influences the far-field divergence angle of the optical antenna, the closer the waveguide spacing, the larger the divergence angle, and the farther the waveguide spacing, the smaller the divergence angle. However, too far a waveguide spacing can also have adverse effects, such as a reduced scanning range of the optical antenna. Therefore, the waveguide pitch of the strip waveguide array 21 cannot be too far or too close, the waveguide pitch of the strip waveguide array 21 can be obtained through multiple experiments, and preferably, in the embodiment, the waveguide pitch of the strip waveguide array 21 is 0.5-5 μm.
In the present embodiment, the width of the wide slab waveguide 23 is influenced by the front end stripe waveguide pitch and the number of the paths, and can be set according to the front end stripe waveguide pitch and the number of the paths, and the length of the wide slab waveguide 23 is greater than 40 μm.
Further, fig. 6 is a schematic cross-sectional structure view of the optical antenna provided in the second embodiment of the present invention after a spacer layer is deposited on the waveguide structure layer, and fig. 7 is a schematic top view of the optical antenna provided in the second embodiment of the present invention after a spacer layer is deposited on the waveguide structure layer. As shown in fig. 6 and 7, in the present embodiment, the spacer layer 3 is deposited above the wide slab waveguide 23, the thickness of the spacer layer 3 directly affects the coupling of the light wave and the grating in the wide waveguide, the thicker the spacer layer 3 is, the less easily the light wave is coupled, and the too thin the spacer layer 3 cannot provide enough low refractive index contrast for the grating, thereby affecting the emission efficiency. The thickness of the spacer layer 3 in this embodiment can be obtained through multiple tests, and preferably, can be 50 to 150 nm.
Preferably, fig. 8 is a schematic cross-sectional structure diagram of the optical antenna provided in the second embodiment of the present invention after depositing a grating material on the spacer layer and etching a grating, and fig. 9 is a schematic top-view structure diagram of the optical antenna provided in the second embodiment of the present invention after depositing a grating material on the spacer layer and etching a grating, as shown in fig. 8 and fig. 9, in this embodiment, the grating structure layer 4 is completely located above the wide slab waveguide 23.
Specifically, when the optical antenna forms the high-refractive-index-contrast grating structure layer 4, the region of the grating structure layer 4 is determined first, and since the wider the waveguide on the top silicon layer 13 of the SOI substrate is, the better the grating coupling effect is, the grating structure layer 4 is completely disposed above the wide slab waveguide 23 to achieve a better coupling effect.
Further, in the present embodiment, the grating period in the grating structure layer 4 is matched with the effective refractive index and the operating wavelength of the wide slab waveguide 23. Preferably, the grating period of the grating structure layer 4 is 1.1 to 1.3 μm.
Specifically, in this embodiment, the grating period in the grating structure layer 4 and the effective refractive index and the operating wavelength of the wide slab waveguide 23 are repeatedly debugged, and the emission result of the optical antenna is checked, so that the grating period in the grating structure layer 4 is matched with the effective refractive index and the operating wavelength of the wide slab waveguide 23, and the wavelength corresponding to the emission peak efficiency of the optical antenna is prevented from deviating from the preset wavelength band.
Preferably, in the present embodiment, the grating thickness and the duty ratio in the grating structure layer 4 satisfy the condition that light is emitted upward in the main lobe.
Specifically, because the thickness and the duty ratio of the grating determine the upward emission state of the light wave coupled into the grating, if the grating structure is proper, the light wave can oscillate in the grating and can be coupled and emitted for multiple times, so that the emission efficiency is greatly improved. And if the grating structure determined by the emission condition of the main lobe can not make the grating lobe form oscillation and emit, the grating lobe is perfectly restrained, and the utilization rate of energy is greatly improved. Therefore, in the present embodiment, the duty ratio of the grating in the grating structure layer 4 is preferably 0.36 to 0.44, and the grating thickness is preferably 420 to 480nm for a wavelength band of 1.5 to 1.6 μm.
In the optical antenna provided by this embodiment, the grating thickness and the duty ratio in the grating structure layer 4 satisfy the condition of the main lobe for emitting light, so that the light wave can be emitted from above the grating with high efficiency, and only the main lobe satisfies the oscillation condition, and the grating lobe does not satisfy the oscillation condition, thereby perfectly suppressing the emission of the grating lobe.
Further, in the present embodiment, the thickness of the protection layer 5 is 2 μm or other values, which is not limited in the present embodiment.
The third embodiment of the present invention provides a phased array lidar, which includes the optical antenna provided in the first or second embodiment.
The structure and function of the optical antenna of the phased array laser radar are the same as those of the optical antenna provided in the first embodiment or the second embodiment, and are not described in detail herein.
Preferably, in the present embodiment, the etching depth of the strip waveguide array 21 in the optical antenna is the same as the thickness of the front-end device to which the optical antenna is connected.
Specifically, because the optical antenna in the phased array laser radar is connected with the front end device, the etching depth of the strip waveguide array 21 in the optical antenna is consistent with the thickness of the front end device connected with the optical antenna, and the front end device may be a device including a curved waveguide, that is, the structure of the strip waveguide array 21 of the optical antenna needs to be consistent with the curved waveguide. In order to minimize the loss, the strip waveguide array 21 is etched by a full etching method, i.e. the etching depth of the strip waveguide array 21 in the optical antenna is equal to the thickness of the top silicon layer 13 of the SOI substrate. If the thickness of the top silicon layer 13 of the SOI substrate is 220nm, the etching depth of the strip waveguide array 21 is 220 nm. The strip waveguide array 21 can minimize the bending loss of the front end bending waveguide and minimize the energy leaked by the waveguide bending.
Fig. 10 is a flowchart of a method for manufacturing an optical antenna according to a fourth embodiment of the present invention, and as shown in fig. 10, the method for manufacturing an optical antenna according to the first embodiment of the present invention can manufacture an antenna according to the first embodiment of the present invention, and the method for manufacturing an optical antenna according to the present embodiment includes the following steps.
In this embodiment, an SOI substrate of a conventional standard CMOS process can be directly obtained, in which the bottom silicon layer 11 is made of silicon and has a thickness of 500 to 600 μm, the buried oxide layer 12 is made of silicon dioxide and has a thickness of 2 μm, and the top silicon layer 13 is made of silicon and has a thickness of 220 nm. Or obtaining other prepared SOI substrates, wherein the material and thickness of each layer are prepared according to different requirements, which is not limited in this embodiment.
Wherein the waveguide structure layer 2 at least comprises: the slab waveguide array 21 may further include a spot-size conversion structure 22 and a wide slab waveguide 23, which is not limited in this embodiment.
The pattern transfer may be performed by electron beam exposure or step-and-step lithography, and the etching method may be an inductively coupled plasma etching method (ICP method for short) or other methods, which is not limited in this embodiment.
Specifically, in the present embodiment, the spacer layer 3 can be deposited on the waveguide layer by using a Plasma Enhanced Chemical Vapor Deposition (PECVD).
The refractive index of the spacer layer 3 is lower than that of the grating structure layer 4, and the difference between the refractive index of the grating structure layer 4 and the refractive index of the spacer layer 3 is greater than a preset threshold value, so that the grating structure layer 4 has high refractive index contrast. The material of the spacer layer 3 may be silicon dioxide.
And 1004, depositing a grating material layer above the spacing layer, and etching the grating material layer to form a grating structure layer.
Specifically, the grating material layer may be deposited by a plasma enhanced chemical vapor deposition method, and the grating material layer may be etched by an electron beam exposure method or a step-and-step lithography method in combination with an ICP method to form the grating structure layer 4.
The grating material layer has a high refractive index and can be a polysilicon layer.
The protective layer 5 has a low refractive index, which may be a silicon dioxide layer, and the difference between the refractive index of the grating structure layer 4 and the refractive index of the protective layer 5 is greater than a preset threshold, so that the grating structure layer 4 has a high refractive index contrast.
The preparation method of the optical antenna provided by the embodiment includes: obtaining an SOI substrate; etching the top silicon layer of the SOI substrate to form a waveguide structure layer; depositing a spacer layer over the waveguide structure layer; depositing a grating material layer above the spacing layer, and etching the grating material layer to form a grating structure layer; growing a protective layer above the grating structure layer; the difference between the refractive index of the grating structure layer and the refractive indexes of the spacing layer and the protective layer is larger than a preset threshold value, and the refractive index of the grating structure layer is higher than the refractive indexes of the spacing layer and the protective layer. Because the spacing layer and the protective layer have low refractive indexes, the grating structure layer has a high refractive index, and the difference values of the refractive indexes of the grating structure layer and the refractive indexes of the spacing layer and the protective layer are larger than a preset threshold value, the grating structure layer has high refractive index contrast, so that when the waveguide structure layer diffracts, the diffraction in the direction of the SOI substrate can be eliminated, and the light wave can be successfully emitted upwards, thereby obtaining high radiation efficiency and further greatly improving the utilization rate of the optical antenna.
Fig. 11 is a flowchart of a method for manufacturing an optical antenna according to a fifth embodiment of the present invention, and as indicated in fig. 11, in the method for manufacturing an optical antenna according to the present embodiment, on the basis of the method for manufacturing an optical antenna according to the fourth embodiment of the present invention, steps 1001 to 1005 are refined, and a step of determining a grating period, a thickness, and a duty ratio in a grating structure layer is further included, so that the method for manufacturing an optical antenna according to the present embodiment includes the following steps.
Further, in the present embodiment, the SOI substrate includes: a bottom silicon layer 11, a buried oxide layer 12 and a top silicon layer 13, the buried oxide layer 12 being located intermediate the bottom silicon layer 11 and the top silicon layer 13.
Specifically, in order to be compatible with the CMOS process, the SOI substrate of the conventional standard CMOS process is employed in the present embodiment. The bottom silicon layer 11 is made of silicon with a thickness of 500-600 μm, the buried oxide layer 12 is made of silicon dioxide with a thickness of 2 μm, and the top silicon layer 13 is made of silicon with a thickness of 220 nm.
Further, in the present embodiment, the waveguide structure layer 2 includes: a strip waveguide array 21, a spot-size conversion structure 22 and a wide slab waveguide 23.
The strip waveguide array 21 and the wide slab waveguide 23 are connected by a spot-size conversion structure 22.
Specifically, in the present embodiment, each of the strip waveguides in the strip waveguide array 21 has a uniform size and is horizontally distributed. Each strip waveguide is connected with the wide slab waveguide 23 through the spot-size conversion structure 22, so that the light waves are well transferred from each strip waveguide to the wide slab waveguide 23, and energy loss caused by mismatching of front and rear waveguide spots is reduced.
Preferably, in the present embodiment, the spot size conversion structure 22 is a trapezoid structure or a trapezoid-like structure, and a short bottom side of the spot size conversion structure 22 is close to the slab waveguide array 21. Therefore, the light wave can be more smoothly transited from each strip waveguide to the wide slab waveguide 23, and the energy loss caused by mismatching of front and rear waveguide mode spots is further reduced.
Preferably, in the present embodiment, the waveguide width of the strip waveguide array 21 in which the optical antenna is provided is 400 to 600 nm. The waveguide pitch of the strip waveguide array 21 is 0.5 to 5 μm. The length of the wide slab waveguide 23 is greater than 40 μm.
At step 1103, a spacer layer is deposited over the waveguide structure layer.
Specifically, in the present embodiment, before depositing the spacer layer 3 above the waveguide structure layer 2, the thickness of the spacer layer 3 needs to be set, and in the present embodiment, the thickness of the spacer layer 3 can be obtained through multiple experiments, and preferably, can be 50 to 150 nm.
And 1104, setting a grating period in the grating structure layer according to a light wave band emitted by the optical antenna, and calculating the grating thickness and the duty ratio in the grating structure layer according to the condition that the main lobe emits light upwards.
Further, in this embodiment, the grating period in the grating structure layer 4 and the effective refractive index and the working wavelength of the wide slab waveguide 23 are repeatedly debugged, and the emission result of the optical antenna is checked, so that the grating period in the grating structure layer 4 is matched with the effective refractive index and the working wavelength of the wide slab waveguide 23, and the wavelength corresponding to the emission peak efficiency of the optical antenna is prevented from deviating from the preset waveband.
Preferably, the grating period of the grating structure layer 4 is 1.1 to 1.3 μm.
Furthermore, because the thickness and the duty ratio of the grating determine the upward emission state of the light wave coupled into the grating, if the grating structure is proper, the light wave can form oscillation in the grating and carry out coupling and emission for many times, thereby greatly improving the emission efficiency. And if the grating structure determined by the emission condition of the main lobe can not make the grating lobe form oscillation and emit, the grating lobe is perfectly restrained, and the utilization rate of energy is greatly improved. Therefore, in the present embodiment, the duty ratio of the grating in the grating structure layer 4 is preferably 0.36 to 0.44, and the grating thickness is preferably 420 to 480nm for a wavelength band of 1.5 to 1.6 μm.
At step 1106, a protective layer is grown over the grating structure layer.
The method for manufacturing an optical antenna provided in this embodiment further includes, before depositing the grating material layer over the spacer layer: setting a grating period in the grating structure layer according to a light wave band emitted by the optical antenna, so that the grating period is matched with the effective refractive index of the wide slab waveguide; according to the condition of main lobe light emission, calculating the grating thickness and the duty ratio in the grating structure layer, wherein the grating thickness and the duty ratio in the grating structure layer are enough for the condition of main lobe light emission, so that light waves can be emitted from the upper part of the grating with high efficiency, only the main lobe meets the oscillation condition, and the grating lobe does not meet the oscillation condition, thereby perfectly inhibiting the emission of the grating lobe.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (12)
1. An optical antenna, comprising: the device comprises an SOI substrate, a waveguide structure layer, a spacing layer, a grating structure layer and a protective layer;
the SOI substrate includes: a bottom silicon layer, a buried oxide layer and a top silicon layer;
forming the waveguide structure layer on the top silicon layer of the SOI substrate, and sequentially arranging a spacing layer, a grating structure layer and a protective layer above the waveguide structure layer;
the difference values of the refractive index of the grating structure layer and the refractive indexes of the spacing layer and the protective layer are both larger than a preset threshold value, and the refractive index of the grating structure layer is higher than the refractive indexes of the spacing layer and the protective layer;
the waveguide structure layer comprises a wide slab waveguide, the grating period in the grating structure layer is matched with the effective refractive index and the working wavelength of the wide slab waveguide, and the grating thickness and the duty ratio in the grating structure layer meet the condition of emitting light upwards with a main lobe.
2. The optical antenna of claim 1, wherein the buried oxide layer is located intermediate the bottom silicon layer and the top silicon layer.
3. The optical antenna of claim 1, wherein the waveguide structure layer further comprises: a strip waveguide array and a spot conversion structure;
the strip waveguide array and the wide slab waveguide are connected through the spot-size conversion structure.
4. The optical antenna of claim 3, wherein the spot-size converting structure is a trapezoid structure or a trapezoid-like structure with a curved oblique side, and a short bottom side of the spot-size converting structure is close to the strip waveguide array.
5. The optical antenna of claim 4, wherein the grating structure layer is located entirely above the wide slab waveguide.
6. An optical antenna according to claim 1, characterized in that said predetermined threshold value takes a value between 0.5 and 2.5.
7. The optical antenna according to claim 1, wherein the optical antenna is adapted to a light wave band of 1.5-1.6 μm, and the thickness of the spacer layer is 50-150 nm.
8. An optical antenna according to claim 1, wherein the length of the wide slab waveguide is greater than 40 μm and the grating period in the grating structure layer is 1.1-1.3 μm.
9. A phased array lidar characterized by comprising an optical antenna according to any of claims 1-8.
10. The phased array lidar of claim 9, wherein the depth of the etching of the array of strip waveguides in the optical antenna is consistent with the thickness of the front-end device to which the optical antenna is connected.
11. A method of manufacturing an optical antenna according to any of claims 1 to 8, comprising:
obtaining an SOI substrate;
etching the top silicon layer of the SOI substrate to form a waveguide structure layer;
depositing a spacer layer over the waveguide structure layer;
depositing a grating material layer above the spacing layer, and etching the grating material layer to form a grating structure layer;
growing a protective layer above the grating structure layer;
the difference between the refractive index of the grating structure layer and the refractive indexes of the spacing layer and the protective layer is larger than a preset threshold value, and the refractive index of the grating structure layer is higher than the refractive indexes of the spacing layer and the protective layer.
12. The method of claim 11, wherein prior to depositing a layer of grating material over the spacer layer, further comprising:
setting a grating period in the grating structure layer according to a light wave band emitted by the optical antenna, so that the grating period is matched with the effective refractive index and the working wavelength of the wide slab waveguide;
and calculating the grating thickness and the duty ratio in the grating structure layer according to the condition that the main lobe emits light upwards.
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| CN111399114B (en) * | 2020-04-02 | 2022-09-02 | 中国科学院微电子研究所 | Design method of grating antenna |
| CN111897051A (en) * | 2020-08-24 | 2020-11-06 | 国科光芯(海宁)科技股份有限公司 | Waveguide grating structure and preparation method thereof |
| CN112630884B (en) * | 2020-12-22 | 2023-09-08 | 联合微电子中心有限责任公司 | Waveguide grating antenna array for optical phased array and preparation method thereof |
| CN114815057A (en) * | 2022-05-05 | 2022-07-29 | 武汉大学 | Focusing type vertical grating coupler and preparation method thereof |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103635785A (en) * | 2011-02-15 | 2014-03-12 | 勒克思马克斯科技公司 | A fully integrated complementary metal oxide semiconductor (CMOS) fourier transform infrared (FTIR) spectrometer and raman spectrometer and method thereof |
| CN103837937A (en) * | 2014-03-19 | 2014-06-04 | 清华大学深圳研究生院 | Prism-grating optical waveguide coupler and optical waveguide device |
| CN104635298A (en) * | 2015-02-11 | 2015-05-20 | 深圳太辰光通信股份有限公司 | Planar optical waveguide and manufacturing method thereof |
| CN105676369A (en) * | 2014-10-24 | 2016-06-15 | 泰科电子公司 | Light-Coupling Structure And Optical Device Including A Grating Coupler |
| WO2016197376A1 (en) * | 2015-06-11 | 2016-12-15 | 华为技术有限公司 | Grating coupler and preparation method therefor |
| CN107765363A (en) * | 2016-08-17 | 2018-03-06 | 三星电子株式会社 | Optical phased array arranges（OPA） |
| CN107924027A (en) * | 2015-06-12 | 2018-04-17 | 加利福尼亚太平洋生物科学股份有限公司 | Integrated target spot waveguide device and system for optical coupling |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017106880A1 (en) * | 2015-12-17 | 2017-06-22 | Finisar Corporation | Surface coupled systems |
-
2018
- 2018-04-19 CN CN201810355993.2A patent/CN110389407B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103635785A (en) * | 2011-02-15 | 2014-03-12 | 勒克思马克斯科技公司 | A fully integrated complementary metal oxide semiconductor (CMOS) fourier transform infrared (FTIR) spectrometer and raman spectrometer and method thereof |
| CN103837937A (en) * | 2014-03-19 | 2014-06-04 | 清华大学深圳研究生院 | Prism-grating optical waveguide coupler and optical waveguide device |
| CN105676369A (en) * | 2014-10-24 | 2016-06-15 | 泰科电子公司 | Light-Coupling Structure And Optical Device Including A Grating Coupler |
| CN104635298A (en) * | 2015-02-11 | 2015-05-20 | 深圳太辰光通信股份有限公司 | Planar optical waveguide and manufacturing method thereof |
| WO2016197376A1 (en) * | 2015-06-11 | 2016-12-15 | 华为技术有限公司 | Grating coupler and preparation method therefor |
| CN107924027A (en) * | 2015-06-12 | 2018-04-17 | 加利福尼亚太平洋生物科学股份有限公司 | Integrated target spot waveguide device and system for optical coupling |
| CN107765363A (en) * | 2016-08-17 | 2018-03-06 | 三星电子株式会社 | Optical phased array arranges（OPA） |
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