CN108776367B - High-density photonic integrated waveguide grating array - Google Patents
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- 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
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- G02B6/12009—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 forming wavelength selective elements, e.g. multiplexer, demultiplexer comprising arrayed waveguide grating [AWG] devices, i.e. with a phased array of waveguides
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- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
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Abstract
A high density photonic integrated waveguide grating array. Apparatus for transmitting multiple optical signals, comprising 3 or more waveguide gratings arranged in parallel; each waveguide grating has a propagation constant different from that of other adjacent waveguide gratings; the period of each grating is related to the propagation constant of the waveguide, and optical signals can be emitted at the same angle through different waveguide gratings. Because the interval between the waveguide gratings is very small, the array is suitable for an optical phased array antenna, and large-angle transverse scanning is realized by changing the relative phase difference between all the waveguide gratings, so that the array has a very wide application prospect in the fields of laser radar, medical imaging, wireless communication and the like.
Description
Technical Field
The invention relates to a photoelectronic integrated device and a preparation method thereof, in particular to a high-density photonic integrated waveguide grating array.
Background
The silicon-based photonic device has a huge application prospect in the aspect of large-scale photoelectron integration due to the advantage of low cost, and is also an important means for realizing an optical phased array. The optical phased array has the characteristics of low cost, high speed and high precision, and has important application in the aspects of laser radar, medical imaging, wireless communication and the like. In order to further improve the scanning accuracy and the scanning angle of the optical phased array, how to improve the density of the phased array antenna is an important problem to be solved.
In the era of big data and artificial intelligence, the automatic driving technology is receiving wide attention to solve the problem of traffic accidents caused by the situations of insufficient driving technology, fatigue driving and the like of drivers. The lidar is one of the core components of the automatic driving technology and is used for collecting environmental information around the vehicle. The traditional laser radar is realized by mechanical scanning, and has the defects of high cost, low speed, low precision and the like. Optical phased array technology can just solve this series of problems. The optical phased array technology is realized by a silicon-based photonic integrated device, is compatible with the developed mature CMOS technology, can be produced in large scale and batch, and has the characteristic of low cost. The scanning of the optical phased array angle is realized by changing the phase of the phased array antenna, and compared with the traditional mechanical scanning, the scanning device has the advantages of higher speed and higher precision.
The precision and scanning range of an optical phased array are related to the scale of a phased array antenna, a waveguide grating array. Generally speaking, the scanning range of an optical phased array is related to the transmitting unit pitch, i.e., the spacing between waveguide gratings herein, and the smaller the spacing, the larger the scanning range. Therefore, the realization of a high-density waveguide grating array is of great significance for improving the performance of an optical phased array.
The basic structure of a waveguide grating array is to add a grating structure to the waveguide array, which can couple light from the waveguide into free space. When the distance between the waveguides is reduced to be close to the optical wavelength or even shorter than the optical wavelength, strong coupling occurs between the waveguides, so that crosstalk between different channels cannot be avoided, and the performance of the device is greatly influenced. The use of waveguide superlattices is a viable solution. By changing the propagation constants of the adjacent waveguides, the propagation constants of the adjacent waveguides are inconsistent, so that the crosstalk among the waveguides is effectively inhibited. Where adjacent waveguides include relatively closely spaced waveguides where crosstalk may occur, crosstalk may occur between next-to-adjacent, 3 rd-adjacent waveguides, or even further-from-adjacent waveguides at high densities where immediately adjacent waveguides are spaced less than two wavelengths. The large-scale high-density waveguide array is obtained by periodically arranging the group of waveguides with different propagation constants. The wavelength in the present application refers to a wavelength in a vacuum unless otherwise specified. A high density of waveguides corresponds to a waveguide spacing of less than two wavelengths or a spatial density of more than 1 waveguide per two wavelength distance.
High density waveguide grating arrays also reduce crosstalk by similar principles. For high density waveguide arrays with waveguide spacing close to or less than the wavelength, it is difficult to achieve low crosstalk between all waveguides by the general method of randomly changing the propagation constants of the waveguides. The design requires that the elements of the effective coupling matrix K between the waveguides should satisfy the following relationship if low cross talk between all waveguides is desired.
Wherein Kmm,KnnIs a diagonal element. Kmk,KnkAre non-diagonal elements. The effective coupling matrix in the above formula can be obtained by coupled wave Theory, and the specific principle can be referred to W.Song et al, "High-sensitivity Waveguide substrates with Low cross talk," Nature Communications 6,7027(2015), and N.Yang et al, "Theory of High-sensitivity Low-cross Waveguide substrates," Photonic Research 4,233-239 (2016). Note that the waveguide in the present invention is a waveguide including a grating, and the waveguide in the above document does not include a grating. The effective coupling matrix of the present invention is obtained for such a waveguide array containing gratings. Due to the grating structure on the waveguides of different propagation constants, a phased array antenna array is formed. The exit angle of the light beam, the propagation constant of the waveguide grating and the period of the grating are all related, and in order to make the divergence angle of the light beam as small as possible, the exit angle of each waveguide grating must be made uniform. Due to the fact that propagation constants of adjacent waveguide gratings are different, the period of the grating must be accurately designed to ensure that the final light beam emergence angles are the same, which is a key problem of a high-density optical phased array antenna array.
The waveguide grating array is completely different from a conventional arrayed waveguide grating (arrayed waveguide grating) in structure, working mode and working mechanism, and can not be confused. The waveguide grating array structure herein contains one grating per waveguide. Conventional arrayed waveguide gratings do not explicitly include gratings themselves, but rather a grating is equivalently generated by phase differences between waveguides. The structure here emits light into free space, whereas conventional arrayed waveguide gratings typically emit light into a slab waveguide within the chip. The structure can realize two-dimensional regulation and control of the beam angle, can be used for application of laser radars and the like, and the traditional array waveguide grating only realizes one-dimensional regulation and control of the beam angle in a chip plane in practice and is usually used for application of wavelength division multiplexing, spectrometers and the like.
Disclosure of Invention
The invention aims to provide a device for transmitting multiple optical signals, in particular to a high-density waveguide grating array applicable to an optical phased array and application. The high-density waveguide grating array structure (device) for the optical phased array provided by the invention emits light to a free space, and can realize two-dimensional regulation and control of a beam angle.
The technical scheme of the invention is as follows: an apparatus for transmitting multiple optical signals, i.e. a high-density waveguide grating array for an optical phased array, comprising 3 or more waveguide gratings arranged in parallel; each waveguide grating has a propagation constant different from that of the adjacent waveguide grating; the period of each grating is related to the propagation constant of the waveguide in which the grating is located, and optical signals can be emitted at the same angle through different waveguide gratings; wherein the distance between the waveguide gratings is below two wavelengths; the waveguide structure is realized by a strip waveguide, a ridge waveguide or a composite structure waveguide; the emergent angle of the optical signal of each waveguide grating is accurately controlled by the grating period, and waveguide gratings with different propagation constants select different periods so as to enable the whole waveguide grating array to emit the optical signal at the same angle.
Further, the difference in the propagation constants of two adjacent waveguide gratings may be obtained by making waveguides having different heights or widths; or the difference in the propagation constants of two adjacent waveguide gratings may be obtained by adding different materials to the waveguide.
Further, wherein the propagation constant of the waveguide grating structure: locally changing the width or height of the waveguide by etching the original waveguide structure, wherein the local change occurs at a plurality of positions and the distribution is periodic or nearly periodic; or by locally adding the same or different material around the original waveguide structure to produce a spatially local change in refractive index, which occurs at a plurality of locations, the distribution of which may be periodic or nearly periodic.
Further, each waveguide grating may be a nearly periodic grating, and the waveguide constant in each waveguide grating and the slow change in the grating period in the waveguide propagation direction should be properly matched to achieve the same angle of light emitted from different positions of each waveguide grating. The waveguide grating array is composed of a plurality of repeated array units, and each array unit comprises a plurality of different waveguide gratings. The spacing between the waveguide gratings is the same as the wavelength order, even less than or equal to half wavelength, so that the density of the waveguide grating array can be greatly improved. In order to reduce crosstalk between waveguide grating arrays, a waveguide superlattice structure is introduced, and propagation constants of waveguide modes of waveguide gratings in the same array unit are different.
The invention is applied to a device for transmitting, controlling or emitting optical signals based on the high-density waveguide grating array of the optical phased array, which comprises a splitter for splitting an incident optical signal into 3 paths or more than 3 paths of optical signals; the phase shifting units with corresponding number can independently change the phase of each optical signal; the transmitting antenna is composed of a corresponding number of waveguide gratings, and transmits optical signals from the waveguide gratings into free space, wherein the propagation constant of each waveguide grating is different from that of other adjacent waveguide gratings.
The splitter can be realized by a directional coupler, a Y-shaped splitter, a multi-mode interference structure or a star coupler, and the splitter can comprise a plurality of sub-splitters.
The phase shift unit can be realized by heating the waveguide or changing the carrier concentration of the waveguide material or applying an electric field or a magnetic field.
The waveguide structure of the waveguide grating transmitting antenna can be realized by a strip waveguide, a ridge waveguide or a composite structure waveguide.
The waveguide grating transmitting antenna structure can be realized by etching the original waveguide structure to locally change the width or height of the waveguide, wherein the local change occurs at a plurality of positions, and the distribution of the local change can be periodic or nearly periodic.
The waveguide grating transmitting antenna structure can be realized by locally adding the same or different materials around the original waveguide structure to generate local change of the refractive index in space, the local change occurs in a plurality of positions, and the distribution can be periodic or nearly periodic.
Wherein the difference in propagation constants of two adjacent waveguide grating transmit antennas can be obtained by making the waveguides with different heights or widths.
Wherein the difference in propagation constants of two adjacent waveguide grating transmit antennas can be obtained by adding different materials to the waveguide.
The emergent angle of the optical signal of each waveguide grating transmitting antenna is accurately controlled by the grating period, and the waveguide grating transmitting antennas with different propagation constants select different periods so as to transmit the optical signal at the same angle by each waveguide grating in the whole waveguide grating transmitting antenna.
Each waveguide grating may be a nearly periodic grating in which the waveguide constants and the slow variation of the grating period in the direction of waveguide propagation should be properly matched to achieve the same angle of light emitted from different positions of each waveguide grating.
The high-density waveguide grating array for the optical phased array has the beneficial effects that the high-density waveguide grating array for the optical phased array can emit light to a free space, wherein the distance between waveguide gratings is below two wavelengths (the distance between waveguide gratings can be reduced to be below one wavelength especially for increasing the scanning angle; the distance between waveguide gratings can be reduced to be below 180 ideal scanning angles; further, the distance between waveguide gratings can be reduced to be half wavelength or less), so that the high-density optical phased array transmitting antenna is formed, and the scanning range and the precision of the high-density optical phased array transmitting antenna are higher than those of a common optical phased array. Such high performance optical phased array technologies may be used in a variety of scenarios such as lidar, medical imaging, wireless communications, and the like.
The adjacent waveguide gratings have different propagation constants, so that the crosstalk between the waveguide gratings is effectively reduced. Different propagation constants are achieved by varying the width, height, or using different materials for the waveguide. Wherein the grating structure is realized by etching the waveguide in width or height, or by adding other same or different materials around the waveguide. The period of the grating must be strictly designed to ensure that different waveguide gratings have the same exit angle. Two-dimensional regulation and control of the beam angle can be realized. In order to reduce crosstalk between waveguide grating arrays, a waveguide superlattice structure is introduced, and propagation constants of waveguide modes of waveguide gratings in the same array unit are different. The periods of different waveguide gratings are precisely designed, so that the influence caused by different propagation constants is counteracted, and all the waveguide gratings can have corresponding emergence angles under the input of specific wavelengths. Because the interval between the waveguide gratings is very small, the array is suitable for an optical phased array antenna, and large-angle transverse scanning is realized by changing the relative phase difference between all the waveguide gratings, so that the array has a very wide application prospect in the fields of laser radar, medical imaging, wireless communication and the like.
Drawings
FIG. 1 is a schematic diagram of a high density waveguide grating array;
FIG. 2 is a side view of a waveguide grating array;
fig. 3 shows a usable waveguide structure a, a slab waveguide b, a rib waveguide;
FIG. 4 illustrates several useful grating structures; a. a first etched grating, b a second etched grating, c a grating formed by adding a material;
fig. 5 shows the results of crosstalk calculations between waveguides in a waveguide grating array at half-wavelength spacing after the use of a waveguide superlattice.
Fig. 6 shows the results of the calculation of the angular distribution characteristics of the emitted light field of the waveguide grating array after the waveguide superlattice is used.
FIG. 7 is a schematic diagram of an optical phased array including a high density waveguide grating array.
In the figure, 1, a silicon substrate layer, 2, a silicon oxide layer, 3, a working silicon layer, 4, a top silicon dioxide protective layer, 5 to 9, five waveguide gratings with different propagation constants, 10, a waveguide grating array unit, 11, a strip waveguide, 12, a ridge waveguide, 13, a first etched grating, 14, a second etched grating, and 15, a grating formed by adding materials. 101. A splitter. 102. A phase shifter. 103. A waveguide grating array.
Detailed Description
[ example 1 ]
The high density optical phased array antenna array is implemented on silicon-on-insulator (SOI) as shown in fig. 1. The structure can be divided into four layers: a silicon substrate 1, a silicon oxide layer 2, a silicon layer 3 defining the device and a top-covering silicon dioxide layer 4, the bulk of the device being on the silicon layer 3. The phased array antenna array consists of four repeated array elements 10, each array element comprising five different waveguide gratings 5-9 with different waveguide widths, so that the waveguide modes have different propagation constants. The light propagates in the waveguide in the x-direction (exactly the-x direction) in this example. Wherein the grating structure is obtained by etching 13, 14. Each grating has different periods, and the light signals are ensured to be emitted at the same angle. The specific relationship can be obtained by the following formula:
where beta is the propagation constant of the waveguide grating, Λ is the period of the grating, k0Is the wave vector of light in air, theta0Is the exit angle of the light after passing through the waveguide grating. When the required angle theta is reached0After determination, according to the propagation constant β of the waveguide grating, the corresponding required grating period Λ (fig. 2) can be calculated. More generally, light can also be emitted by designing other diffraction orders using gratings, where β -n (2 pi/Λ) ═ k0sinθ0Wherein n may be any integer n ═ 0, ± 1, ± 2, ….
[ example 2 ]
The number of the array units is not limited to four, and can be increased or decreased according to the requirement, for example, 3-1000. The number of waveguide gratings per array unit is also not limited to five, e.g., 2-20.
[ example 3 ]
The waveguide structure may use not only the strip waveguide 11 but also the ridge waveguide 12, or other waveguide forms.
[ example 4 ]
The waveguide grating structure can be obtained by etching to locally change the waveguide height (as shown in 13) or to locally change the waveguide width (as shown in 15), or to change both height and width. It may also be achieved by locally adding the same or different materials (as shown in the waveguide structure 15) around the waveguide (up-down or left-right). In a specific implementation method, the waveguide structure 15 may also be obtained by depositing an additional material on a large-area thin film, and then etching the additional material to locally change the height or width of the remaining material, or change both the height and width of the remaining material.
Essentially the grating structure requires that the refractive index is a function n (x, y, z) of the spatial position (x, y, z), which in general should be a periodic function, e.g. n (x + Λ, y, z) ═ n (x, y, z), where Λ is the grating period. Chirped gratings or more complex gratings may also have a slow modulation of the refractive index based on the periodic variation, for example n (x + Λ, y, z) ═ n (x, y, z) × m (x), where m (x) varies by much less than 1 over any interval [ x, x + Λ ]. For example, m (x) may be a function that decreases slowly with increasing | x |. A slow modulation of the refractive index in a chirped grating or more complex grating may also be manifested as a slow variation of the period of the grating or the phase of the grating with x.
The refractive index can be locally changed as long as a portion of the material is locally etched away, so that the refractive index becomes a function of spatial position (x, y, z). A similar effect can be achieved by locally adding material. This local change occurs at multiple locations, the distribution of which may be periodic or nearly periodic. Changing the etch width or etch depth locally and periodically or adding material changes the refractive index periodically. For the cases in fig. 1 and 4, the refractive index is a periodic function along the x-direction. M (x) in the above chirped grating or more complex grating, if a function slowly decreases with increasing | x |, can be achieved by slowly changing the etch depth or etch width away from the periodicity on the basis of periodically changing the etch depth or etch width. Such a grating structure can be considered to be nearly periodic. If the slowly varying function m (x) causes a waveguide parameter such as the propagation constant β to vary slowly with x, the exit angle in equation (2) can be made invariant with x by slowly varying a grating parameter such as the grating period Λ with x. That is, if the waveguide constant and the grating period in each waveguide grating change slowly along the waveguide propagation direction, it can be realized that the light emitted from different positions of each waveguide grating has the same angle as long as their changes are properly matched to ensure that the exit angle in formula (2) is unchanged.
When the waveguide grating array works, an optical signal enters the waveguide grating array from an arrow A and is coupled into air from an arrow B under the action of the grating. The beam is at theta (theta)0) The angular deflection may be achieved by changing the wavelength of the optical signal entering the waveguide grating, the specific relationship being determined as in equation (2). The deflection of the beam at the angle psi is controlled by the phase gradient between the individual waveguide gratings, as follows:
wherein λ0Is the wavelength of light, phi is the phase difference of light signals in adjacent waveguide gratings, and d is the period of the waveguide grating units. Refers to the distance between the center lines of two waveguides which are directly adjacent, i.e. the distance between two waveguides which are directly adjacent in the y direction in fig. 1. In the actual working process, before the optical signal enters the waveguide grating array, one path of optical signal is divided into a plurality of paths, and the divided optical signal of each path generates the required phase difference through the modulation of a thermo-optical or electro-optical phase shifter and then is input into the waveguide grating array. As can be seen from equation (3), when the phase difference of adjacent waveguide gratings varies from-pi to pi in the case where the interval of the waveguide grating arrangement is narrowed to a half wavelength, scanning of the light beam at an angle of phi ± 90 ° can be obtained.
According to the basic principle of a phased array, the angle ψ n of n-order sub-beams (sometimes also referred to as grating lobes) of the phased array is satisfied;
sinψn＝nλ/d+sinψ0. (4)
n-0 is the main beam and n is not equal to 0 is the sub-beam. The waveguide density is increased, i.e., the waveguide pitch d is correspondingly decreased, when the high-density waveguide pitch d is less than or equal to half wavelength, the angle psi of the main beam is obtained according to the formula 40Whatever the value, all the secondary beams disappear. This is exactly what is meant by the use of high density waveguide grating arrays. If the distance between waveguide gratings is above two wavelengths, the included angle between the sub-beam and the main beam is usually too small, and the scanning angle is limited by the sub-beam. To increase the scanning angle, the distance between waveguide gratings can be reduced to two wavelengths or even below one wavelength. To achieve a desired scan angle of 180 degrees, the distance between waveguide gratings should be reduced to half a wavelength or less. Fig. 5 shows the crosstalk between waveguides at half wavelength spacing, all below-20 dB, when the waveguide superlattice technology is used to tune different waveguides with different propagation constants. All the above theories regarding phased arrays can only hold true if it is ensured that the crosstalk between the different waveguides is sufficiently low. When the crosstalk between the waveguides is large, the phase between the channels is influenced by the crosstalk and obviously deviates from an ideal value, so that the phased array cannot normally work according to the standard theory description of the phased array, and a stray light beam or other harmful effects which are difficult to control are generated. Fig. 6 shows that in the case of using a high-density waveguide grating array, there is only one main beam in the far field, and the case of 0 degrees (solid line) and the case of 40 degrees (dotted line) are shown at the same time.
A schematic diagram of an optical phased array using a high density waveguide grating array is shown in fig. 7. Light is coupled into splitter 101 from the left and phase shifted by phase shifter 102. Light is emitted through the waveguide grating array 103 into free space. The splitter, the phase shifter (or phase shift unit), and the waveguide grating array may be connected by a waveguide, or may couple light among these devices in other ways. The splitter 101 may be composed of a plurality of sub-splitters. The phase shifter can control the refractive index and phase change by thermo-optic effect, electro-optic effect, refractive index change effect due to carrier concentration, and magneto-optic effect. By changing the phase of the phase shifter, in combination with changing the wavelength, a two-dimensional scan of the beam pointing can be achieved.
The embodiments of the invention do not limit the scope of the invention, but rather the scope of the invention is defined by the claims and the associated explanations.
Claims (12)
1. An apparatus for transmitting a plurality of optical signals, comprising 3 or more waveguide gratings arranged in parallel; each waveguide grating has a propagation constant different from that of other adjacent waveguide gratings; the period of each grating is related to the propagation constant of the waveguide in which the grating is located, and optical signals can be emitted at the same angle through different waveguide gratings; wherein elements of an effective coupling matrix [ K ] between the waveguides containing the grating satisfy the following relationship:
wherein K ismm、KnnIs a diagonal member, Kmk、KnkIs a non-diagonal element;
wherein each waveguide grating satisfies:
β-n(2π/Λ)＝k0sinθ0，
where beta is the propagation constant of the waveguide grating, Λ is the period of the waveguide grating, k0Is the wave vector of light in air, theta0Is the emergent angle of light passing through the waveguide grating, and n can be any integer; the numerical value of beta and lambda of each waveguide grating in the array keeps the emergent angle theta0The same;
wherein the grating may be periodic or nearly periodic; in a nearly periodic grating, the waveguide propagation constant and the grating period vary with the direction of propagation in the waveguide, but their variation match ensures that the exit angle is constant, with the variation of the index modulation function much less than 1 within one grating period.
2. The apparatus of claim 1, wherein the waveguide structure is implemented by a strip waveguide, a ridge waveguide or a composite waveguide.
3. The apparatus of claim 1, wherein the waveguide grating structure is implemented by etching the original waveguide structure to locally change the width or height of the waveguide, the local change occurring at a plurality of locations, the distribution of locations being periodic or nearly periodic, and wherein the waveguide grating structure is implemented by locally adding the same or different materials around the original waveguide structure to generate a spatially local change in the refractive index, the local change occurring at a plurality of locations, the distribution of locations being periodic or nearly periodic.
4. The apparatus of claim 1, wherein the difference in propagation constants of two adjacent waveguide gratings is obtained by forming waveguides having different heights or widths, or by adding different materials to the waveguides.
5. The apparatus of claim 1, wherein the exit angle of the optical signal from each waveguide grating is precisely controlled by the grating period, and waveguide gratings with different propagation constants have different periods selected so that the entire waveguide grating array emits the optical signal at the same angle.
6. The apparatus of claim 1, wherein each waveguide grating is a nearly periodic grating, and the waveguide constant of each waveguide grating and the slow variation of the grating period in the waveguide propagation direction are properly matched to achieve the same angle of light emitted from different positions of each waveguide grating.
7. An apparatus for transmitting, controlling or transmitting an optical signal, comprising a splitter for splitting an incoming optical signal into 3 or more than 3 optical signals; the phase shifting units with corresponding number can independently change the phase of each optical signal; the transmitting antenna formed by the corresponding number of waveguide gratings transmits optical signals from the waveguides to enter a free space, wherein the propagation constant of each waveguide grating is different from that of other adjacent waveguide gratings, and the elements of an effective coupling matrix [ K ] between the waveguides containing the gratings satisfy the following relations:
wherein K ismm、KnnIs a diagonal member, Kmk、KnkIs a non-diagonal element;
wherein each waveguide grating satisfies:
β-n(2π/Λ)＝k0sinθ0，
where beta is the propagation constant of the waveguide grating, Λ is the period of the waveguide grating, k0Is the wave vector of light in air, theta0Is the emergent angle of light passing through the waveguide grating, and n can be any integer; the numerical value of beta and lambda of each waveguide grating in the array keeps the emergent angle theta0The same;
wherein the grating may be periodic or nearly periodic; in a nearly periodic grating, the waveguide propagation constant and the grating period vary with the direction of propagation in the waveguide, but their variation match ensures that the exit angle is constant, with the variation of the index modulation function much less than 1 within one grating period.
8. Apparatus for transmitting, controlling or transmitting optical signals according to claim 7, in which the splitter comprises a plurality of sub-splitters, the or each sub-splitter being implemented by means of a directional coupler, a Y-splitter, a multimode interference structure or a star coupler; the phase shifting unit can be realized by heating the waveguide or changing the carrier concentration of the waveguide material or applying an electric field or a magnetic field; the waveguide structure of the waveguide grating transmitting antenna can be realized by a strip waveguide, a ridge waveguide or a composite structure waveguide.
9. An apparatus for transmitting, controlling or transmitting an optical signal according to claim 7, wherein the waveguide grating transmitting antenna structure is implemented by etching the original waveguide structure to locally change the width or height of the waveguide, the local change occurring at a plurality of locations, the distribution of locations being periodic or nearly periodic, and wherein the waveguide grating transmitting antenna structure is implemented by locally adding the same or different materials around the original waveguide structure to produce a spatially local change in the refractive index, the local change occurring at a plurality of locations, the distribution of locations being periodic or nearly periodic.
10. An apparatus for transmitting, controlling or transmitting an optical signal according to claim 7, wherein the difference in propagation constants of two adjacent waveguide grating transmitting antennas is obtained by making waveguides with different heights or widths, or by adding different materials to the waveguides.
11. The apparatus according to claim 7, wherein the exit angle of the optical signal from each of the waveguide grating transmitting antennas is precisely controlled by the grating period, and the waveguide grating transmitting antennas having different propagation constants have different periods selected so that the waveguide gratings in the whole waveguide grating transmitting antenna transmit the optical signal at the same angle.
12. An apparatus for transmitting, controlling or transmitting an optical signal as claimed in claim 7, wherein each waveguide grating is a nearly periodic grating, and the waveguide constant of each waveguide grating and the slow variation of the grating period in the direction of waveguide propagation should be properly matched to achieve the same angle of light emission at different positions of each waveguide grating.
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| US11215760B2 (en) | 2020-02-25 | 2022-01-04 | Honeywell International Inc. | Device for emission of arbitrary optical beam profiles from a chip to free space |
| CN111596499A (en) * | 2020-06-17 | 2020-08-28 | 中国科学院微电子研究所 | Waveguide grating antenna construction method and device |
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