Silicon-based optical phased array structure with high sideband suppression ratio and its calculation method

Abstract

The present invention discloses a silicon-based optical phased array with a high sideband suppression ratio, comprising a laser, a coupling beam splitter, a phase modulator, a transmission waveguide, and a coupling grating. The coupling beam splitter, phase modulator, transmission waveguide, and coupling grating are all integrated on a silicon dioxide substrate. The output light beam of the laser enters the coupling beam splitter, which splits the single-path light into multiple paths of light. Each split light path simultaneously enters the phase modulator for phase modulation. The transmission waveguide connects the phase modulator and the coupling grating, and the coupling grating radiates the phase-modulated multiple paths of light into the far field. The present invention also discloses a method for calculating the structure of a silicon-based optical phased array with a high sideband suppression ratio. Advantages: The present invention adjusts the length of the coupling region between the array waveguide and the main waveguide so that the near-field light intensity of the optical phased array satisfies the Gaussian distribution, thereby improving the sideband suppression ratio of the far-field light intensity.

Description

Technical Field

[0001] The present invention relates to the field of laser radar technology, and in particular to a silicon-based optical phased array structure with a high sideband suppression ratio. Background Art

[0002] With the booming development of new energy vehicles, autonomous driving technology has also made significant progress. Against this backdrop, the advantages of LiDAR (LiDAR), which enables long-range, high-precision three-dimensional imaging, are becoming increasingly prominent. The core component of LiDAR is its beam scanning system. Compared to traditional mechanical scanning structures, optical phased arrays (OPAs) are gaining increasing attention due to their advantages, including the lack of internal moving parts, ease of miniaturization, simplified phase calibration, and low cost. The output beam of an OPA appears as a bright spot with a certain angular width in the far field, essentially a result of multi-beam interference. Therefore, the far-field spot contains not only a main lobe but also various sidelobes. The presence of sidelobes significantly reduces the scanning accuracy of an OPA. Therefore, reducing sidelobes in the far-field light intensity and improving the sideband suppression ratio are key tasks in the design and optimization of OPA structures. The sideband suppression ratio of the far-field light intensity is generally required to exceed 30dB.

[0003] Traditional silicon-based optical phased arrays mostly use a multi-level beam splitting structure, and the optical power of the array waveguide is evenly distributed.

[0004] For example, in Optica, journal number 2334-2539, article title: Non-redundant optical phased array, and authors T. Fukui, R. Tanomura, K. Komatsu, D. Yamashita, S. Takahashi, Y. Nakano, and T. Tanemura, the 3dB MMI cascade spectrometer design described in the article implements a non-redundant optical phased array, reducing the number of phase modulators without reducing the scanning resolution points. However, the sideband suppression ratio of far-field measurements is only 7dB.

[0005] For example, in Optical Express, journal number 1094-4089, titled "Sub-wavelength-pitch silicon-photonic optical phased array for large field-of-regard coherent optical beam steering," the authors are Y. Zhang, Y. C. Ling, K. Zhang, C. Gentry, D. Sadighi, G. Whaley, J. Colosimo, P. Suni, and S. J. Ben Yoo. The 3dB MMI cascaded beam splitting design described in this article achieves a large scanning range in both the horizontal and vertical directions. However, the drawbacks are also significant: the waveguide array exhibits significant crosstalk, and its far-field sideband suppression ratio is only 7dB.

[0006] Silicon-based optical phased array structures generally improve the sideband suppression ratio (SSR) of far-field light intensity by reducing crosstalk between arrayed waveguides or by improving the accuracy of initial phase calibration. Crosstalk suppression between waveguide arrays is often achieved through the design of specialized array structures, such as superlattice waveguides, plasmonic waveguides, and metamaterial waveguides. While symmetry-breaking in waveguide array structures can achieve crosstalk suppression to a certain extent, these structures also suffer from processing difficulties, limited crosstalk suppression (optimal crosstalk suppression is around -20dB), and high cost. Furthermore, in practical applications, optical phased arrays must maintain the initial phase of each waveguide consistent, generating a phase gradient based on this phase to achieve beam scanning. Maintaining phase lock across the waveguides is also crucial in practical applications, despite environmental fluctuations (such as temperature and humidity). Currently, deterministic stochastic gradient descent methods and hierarchical stochastic parallel gradient descent methods offer faster optimization convergence and higher phase calibration accuracy, capable of improving SSR to over 25dB. However, the sideband suppression ratio improvement method that relies on the optimization algorithm is greatly affected by environmental factors and is relatively unstable. Furthermore, the improvement in the sideband suppression ratio brought about by phase calibration cannot fully meet the requirements of the radiating antenna. Summary of the Invention

[0007] One of the objectives of the present invention is to propose a silicon-based optical phased array structure with a high sideband suppression ratio. By adjusting the length of the coupling region between the array waveguide and the main waveguide, the near-field light intensity of the optical phased array satisfies the Gaussian distribution, thereby improving the sideband suppression ratio of the far-field light intensity.

[0008] The technical solution adopted is: a silicon-based optical phased array structure with a high sideband suppression ratio, including a laser, a coupled beam splitter, a phase modulator, a transmission waveguide and a coupling grating. The coupled beam splitter, phase modulator, transmission waveguide and coupling grating are all integrated on a silicon dioxide substrate. The output beam of the laser enters the coupled beam splitter, and the coupled beam splitter splits the single-path light into multiple-path light. Each split beam enters the phase modulator at the same time for phase modulation. The transmission waveguide connects the phase modulator and the coupling grating, and the coupling grating radiates the phase-modulated multiple-path light to the far field.

[0009] In a further preferred embodiment of the present invention, the coupled beam splitter has a 1×N beam splitting structure, consisting of a main waveguide with a width of W0 and a beam splitting waveguide array. The beam splitting waveguide array consists of N sub-waveguides with a width of W1, where W1 = W0 and N is a positive integer. Silicon-based optical phased arrays generally use a 1×N beam splitting structure, where 1 represents the main waveguide, which serves as the propagation channel for the light source input; N represents the beam splitting structure, which divides the output beam into N sub-waves. According to the Huygens principle, the propagation direction of the output light can be controlled by adjusting the propagation phase of each sub-wave.

[0010] In a further preferred embodiment of the technical solution of the present invention, the N sub-waveguides of the beam splitting waveguide array are composed of a length of L i The straight waveguide and S-shaped Bezier waveguide (i=1,2,…,N) are cascaded on one side of the main waveguide. The N sub-waveguides are non-uniformly divided into M groups, then:

[0011]

[0012] Among them, m j is the number of sub-waveguides in the j-th (j=1, 2,…, M) group, where M is a positive integer.

[0013] The sub-waveguide consists of a straight waveguide and an S-type Bezier waveguide. The straight waveguide can achieve transmission coupling with the main waveguide, transferring part of the light intensity to the sub-waveguide; the S-type Bezier waveguide guides the coupled light to output. This structure can reduce the loss of light transmission.

[0014] In a further preferred embodiment of the technical solution of the present invention, the phase modulator provides an additional phase for the beam splitting waveguide array, and its change gradient as follows:

[0015]

[0016] Where λ is the wavelength of the light source beam, N eff is the effective refractive index of the light beam propagating in the waveguide, D is the interval period of the output waveguide array, θ s is the scanning pointing angle of the optical phased array.

[0017] Angular scanning in a silicon-based optical phased array is achieved by providing additional phase to the beam-splitting waveguide array through a phase modulator. The pointing angle θs is determined so that the additional phase provided to the sub-waveguides satisfies the aforementioned relationship, ensuring that the output light from the silicon-based optical phased array is a plane wave. The 3D sensing capabilities of lidar require a plane wave scanning beam.

[0018] In a further preferred embodiment of the present invention, the transmission waveguides are arranged in a uniformly distributed array, with N sub-waveguides and a transmission waveguide spacing period of D = αλ, where α is the array spacing factor. This invention primarily constructs a Gaussian near-field light intensity distribution by adjusting the optical power ratio transmitted by the sub-waveguides in the beam-splitting waveguide array. With this design approach, only by ensuring a uniform distribution of transmission waveguides can the Gaussian near-field light intensity achieve a high sideband suppression ratio after Fraunhofer diffraction.

[0019] In a further preferred embodiment of the technical solution of the present invention, the coupled grating is a sub-wavelength grating, and the grating period Λ satisfies the phase matching condition, specifically as follows:

[0020]

[0021] Where λ is the wavelength of the light source beam, n p is the refractive index of the light beam in the exit space, N eff is the effective refractive index of the light beam propagating in the waveguide.

[0022] The subwavelength grating can couple the light beam transmitted in the waveguide outward, thereby enabling scanning of far-field objects. The above phase matching conditions ensure that the light source beam is coupled out perpendicularly from the end face of the subwavelength grating.

[0023] In a further preferred embodiment of the technical solution of the present invention, the laser is an off-chip light source, and the laser is a monochromatic light source for one-dimensional scanning and a broadband light source for two-dimensional scanning.

[0024] Silicon-based optical phased arrays can achieve two-dimensional scanning. Horizontal scanning is primarily achieved by adding a gradient phase to the waveguide array using a phase modulator, so a single-wavelength light source can achieve horizontal scanning. In the vertical direction, beams of different wavelengths coupled through a subwavelength grating exhibit different output angles, a process commonly referred to as wavelength tuning. Therefore, vertical scanning requires a broadband light source.

[0025] A second objective of the present invention is to propose a calculation method for a silicon-based optical phased array structure with a high sideband suppression ratio. This method constructs a continuous mode coupling equation in the propagation direction, uses a genetic algorithm to optimize the coupling between waveguides in groups, and uses the sideband suppression ratio of the silicon-based optical phased array's far-field light intensity as the optimized loss function.

[0026] The technical solution adopted is: a calculation method for a silicon-based optical phased array structure with high sideband suppression ratio, including the following steps:

[0027] S1. Use Gaussian distribution to construct the optical phased array beam splitting weight factor w n (n=1,2,…,N) distribution model;

[0028] S2, according to the main waveguide width W0, the beam waveguide width W1 and the waveguide spacing W g , calculate the coupling coefficient κ; set the propagation mismatch constant Δβ, calculate the coupling length L c ;

[0029] S3. Combine the mode coupling equations between the main waveguide and N sub-waveguides to obtain the main waveguide light field amplitude coefficient A(z) and the sub-waveguide light field amplitude coefficient a n The general solution of (z)(n=1,2,…,N), where z is the propagation distance; with A(z) as the boundary condition, the sub-waveguide light field amplitude coefficient a n (z) distribution model that satisfies the beam splitting weight factor w n The total energy is conserved, and the straight waveguide length L corresponding to the N sub-waveguides is obtained n (n=1,2,…,N);

[0030] S4, N sub-waveguides are non-uniformly divided into M groups, and the number of sub-waveguides in each group is expressed as S m (m=1,2,…,M), the straight waveguide lengths of the neutron waveguides in the same group are the same, and their common length is the average value L of the corresponding straight waveguide lengths in S3 m (S m )(m=1,2,…,M);

[0031] S5. Construct loss function Fitness = f SMSR (S m ,θ), where SMSR represents the sideband suppression ratio of the far-field light intensity;

[0032] S6. Use genetic algorithm to search for the best grouping method of beam splitting waveguide array, that is, S m distribution function to maximize the sideband suppression ratio of the far-field light intensity.

[0033] 9. The calculation method according to claim 8, wherein after the N sub-waveguides are grouped, the average length L of the straight waveguide in each group is m (S m ) is greater than 0.5μm.

[0034] The processing of silicon-based photonic devices will have certain dimensional errors. The small average length difference can easily be covered by the error during the processing process, which in turn causes the energy ratio in the corresponding sub-waveguide to fail to meet the numerical requirements proposed in the present invention, and the far-field sideband suppression ratio of the actual device will also be reduced.

[0035] The beneficial effects of the present invention are:

[0036] 1. The present invention has a silicon-based optical phased array structure with a high sideband suppression ratio. By designing and optimizing the length of the coupling region between the beam splitting waveguide and the main waveguide, precise control of the beam splitting ratio is achieved, and a Gaussian near-field light intensity distribution is realized, thereby improving the sideband suppression ratio of the far-field light intensity and effectively suppressing interference and noise from the sidelobes.

[0037] 2. The present invention has a silicon-based optical phased array structure with a high sideband suppression ratio, which groups the beam splitting waveguides non-uniformly, thereby increasing the diversity of the beam splitting waveguide sizes and improving the practical application value.

[0038] 3. The calculation method of the silicon-based optical phased array structure with high sideband suppression ratio in the present invention is based on the mode coupling theory to obtain the general solution of the amplitude coefficient of the light field in the main waveguide and the beam splitting waveguide array. With the light field amplitude attenuation of the main waveguide as the boundary condition and the distribution of the beam splitting weight factor as the solution target, the length of each beam splitting waveguide coupling region can be quickly calculated. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 1 is a schematic diagram of the structure of a silicon-based optical phased array with high sideband suppression ratio in an embodiment of the present invention;

[0040] Figure 2 is the quantity distribution corresponding to the grouping of the subordinate sub-waveguides of the beam splitting waveguide array in the embodiment of the present invention;

[0041] Figure 3 This is a flow chart of a design optimization method for a silicon-based optical phased array with high sideband suppression ratio according to an embodiment of the present invention;

[0042] Figure 4 is the length of the coupling region corresponding to the beam splitting waveguide array in the embodiment of the present invention;

[0043] Figure 5 is the average adjacent length L of the grouped beam splitting waveguide array in the embodiment of the present invention m (S m ) difference;

[0044] Figure 6 1 is the normalized distribution of light intensity in the far field at different scanning angles in an embodiment of the present invention: (a) 0deg; (b) 10deg; (c) 20deg; (d) 30deg; (e) 40deg; and (f) 50deg. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clear, the following Figure 1-5 It should be understood that the specific embodiments described herein are only used to illustrate the present invention and are not intended to limit the present invention.

[0046] like Figure 1 As shown, this embodiment is a silicon-based optical phased array structure with a high sideband suppression ratio, including a laser 1, a coupled beam splitter 2, a phase modulator 3, a transmission waveguide 4 and a coupled grating 5, wherein the laser 1 is an off-chip light source, and the coupled beam splitter 2, the phase modulator 3, the transmission waveguide 4 and the coupled grating 5 are integrated on a silicon dioxide substrate. The laser 1 generates a light beam which is incident on the main waveguide 2-1 in the coupling beam splitter 2; the beam splitting waveguide array 2-2 is cascaded in sequence on one side of the main waveguide 2-1, and the incident light is coupled to the beam splitting waveguide array 2-2 by direct coupling; the straight waveguide belonging to the coupling area in the beam splitting waveguide array 2-2 is extended outward through an S-type Bezier waveguide, and is connected to the phase modulator 3 through the straight waveguide; the phase modulator 3 realizes phase modulation of the propagating light beam by changing the refractive index of the waveguide area, and the modulation phase distribution of the phase modulator 3 is gradient descending or gradient ascending; one end of the transmission waveguide 4 is connected to the phase modulator 3, and the other end is connected to the coupling grating 5, and the waveguide spacing is equal; the coupling grating 5 is a sub-wavelength grating, which realizes the output coupling of the incident light.

[0047] In this embodiment, the laser 1 can be a monochromatic light source or a broadband light source. The monochromatic light source can only realize one-dimensional scanning of the optical phased array in the horizontal direction, while the broadband light source can realize two-dimensional scanning of the optical phased array in the horizontal and vertical directions through wavelength tuning.

[0048] In this embodiment, the beam splitting waveguide array 2-2 includes N=600 sub-waveguides, which are divided into M=20 groups. The number of waveguides corresponding to each group is S. m like Figure 2 Distribution shown.

[0049] In this embodiment, the phase modulator 3 is connected to an external voltage and uses the thermo-optical effect to add an additional phase to the light field passing through the area. The change gradient as follows:

[0050]

[0051] Where λ is the wavelength of the light source beam, N eff is the effective refractive index of the light beam propagating in the waveguide, D is the interval period of the output waveguide array, θ sis the scanning pointing angle of the optical phased array, which expresses the corresponding relationship between the modulation phase and the scanning pointing angle.

[0052] In this embodiment, the grating period Λ of the coupling grating 5 satisfies the phase matching condition for vertical emission:

[0053]

[0054] Among them, n p is the refractive index of the light beam in the exit space. In this embodiment, the coupling grating 5 applies single radiation, so m=1.

[0055] like Figure 3 As shown, this embodiment is a calculation method for a silicon-based optical phased array structure with a high sideband suppression ratio, comprising the following steps:

[0056] S1, build the optical phased array beam splitting weight factor distribution model, that is, Gaussian distribution. The beam splitting weight factor w n The specific manifestations are as follows:

[0057]

[0058] Where μ is the mean and σ is the standard deviation.

[0059] S2, based on the main waveguide width W0, the beam splitting waveguide array width W1, and the waveguide spacing W g , calculate the coupling coefficient κ. Set the propagation mismatch constant Δβ = 0 and calculate the coupling length L c .

[0060] S3, the mode coupling equations between the main waveguide 2-1 and the N sub-waveguides are combined to obtain the main waveguide light field amplitude coefficient A(z) and the sub-waveguide light field amplitude coefficient a n The general solution of (z)(n=1,2,…,N) is as follows:

[0061]

[0062] Where z is the propagation distance, At the same time, with A(z) as the boundary condition, the amplitude coefficient a n (z) satisfies the Gaussian distribution satisfied by the beam splitting weight factor, and the total energy is conserved, as shown below:

[0063]

[0064] The propagation distance z that satisfies the above formula is the straight waveguide length L belonging to the beam splitting waveguide array 2-2. n (n=1,2,…,N), its distribution is as follows Figure 4 Indicated by the dotted line.

[0065] S4, the sub-waveguides of the beam splitting waveguide array 2-2 are non-uniformly divided into M=20 groups, and the number of sub-waveguides in each group is expressed as S m (m=1,2,…,M). Assume that the straight waveguide lengths in the sub-waveguides of the mth group are the same, and their common length is the average value L of the corresponding straight waveguide lengths in S3. m (S m )(m=1,2,…,M).

[0066] S5, construct the loss function Fitness = f SMSR (S m ,θ), where SMSR represents the sideband suppression ratio of the far-field light intensity, as follows:

[0067] S51, according to the coupled mode equation (4), the light field amplitude coefficient a of the group-averaged beam splitting waveguide array 2-2 is obtained. n (L m (S m ))(m=1,2,…,M), then the light field distribution is:

[0068]

[0069] Where, D = 0.56λ;

[0070] S52, according to formula (6), the array factor AF of the far-field amplitude can be obtained (S m ,θ), as follows:

[0071]

[0072] Where θ is the far-field angular distribution;

[0073] S53, approximate processing. The far-field SMSR is less affected by the far-field light intensity envelope, so AF(S m ,θ) dominates. The sideband suppression ratio of AF can be approximated as the sideband suppression ratio of the far-field light intensity distribution. Finally, AF(S m ,θ) the SMSR of the far-field distribution is used as the loss function.

[0074] S6, using genetic algorithm to search for the best grouping method of beam splitting waveguides, namely S m The distribution function is used to maximize the sideband suppression ratio of the far-field light intensity distribution. Finally, the structure of the coupled beam splitter is determined. m distribution, then the grouped L n Distribution Figure 4 As shown by the solid line. Figure 5 As shown, the average length after grouping is L m (S m ) is greater than 0.5μm, and the length can be effectively distinguished in actual processing. Figure 6 As shown in Figure 2, the distribution of far-field light intensity at different scanning angles is shown, and its SMSR is >39dB.

[0075] Based on mode coupling theory, the near-field output intensity distribution of an optical phased array can be controlled, thereby improving the far-field sideband suppression ratio to 39dB. Optical phased arrays optimized based on grouped design have significant size differences, which makes them easier to implement in actual manufacturing.

[0076] The above embodiments are only for illustrating the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A calculation method for a silicon-based optical phased array structure with high sideband suppression ratio, characterized by: The steps include: S1. Use Gaussian distribution to construct optical phased array beam splitting weight factors w n ( n = 1, 2, …, N ) distribution model; S2, according to the main waveguide width W 0. Beam splitting waveguide width W 1 and waveguide spacing W g , calculate the coupling coefficient κ ; Set the propagation mismatch constant Δ β , calculate the coupling length L c ; S3, combined main waveguide and N The mode coupling equations between the sub-waveguides are used to obtain the main waveguide light field amplitude coefficient A ( z ) and the sub-waveguide optical field amplitude coefficient a n ( z ) ( n = 1, 2, …, N ), where z is the propagation distance; A ( z ) is the boundary condition, the sub-waveguide light field amplitude coefficient a n ( z ) distribution model that satisfies the beam weight factor w n The total energy is conserved, and then we can get N The straight waveguide length corresponding to the sub-waveguide L n ( n = 1, 2, …, N ); Specifically: Combined main waveguide (2-1) and N The mode coupling equations between the sub-waveguides are used to obtain the amplitude coefficient of the main waveguide light field. A ( z ), and the sub-waveguide light field amplitude coefficient a n ( z )( n = 1, 2, …, N ) is as follows: （4） in, z is the propagation distance, At the same time, A ( z ) is the boundary condition, the amplitude coefficient a n ( z ) satisfies the Gaussian distribution satisfied by the beam splitting weight factor, and the total energy is conserved, as shown below: （5） The propagation distance z that satisfies the above formula is the length of the straight waveguide belonging to the beam splitting waveguide array (2-2) L n ( n = 1, 2, …, N ); S4, N The sub-waveguides are non-uniformly divided into M group, the number of sub-waveguides in each group is expressed as S m ( m = 1, 2, …, M ), the straight waveguide lengths of the same group of neutron waveguides are the same, and their common length is the average value of the corresponding straight waveguide lengths in S3 L m ( S m )( m = 1, 2, …, M ); S5. Construct loss function Fitness = f SMSR ( S m , θ ), where SMSR represents the sideband suppression ratio of the far-field intensity; the array factor for the far-field amplitude is obtained AF ( S m , θ ),as follows: （7） in, θ is the far-field angular distribution; S6. Use genetic algorithm to search for the best grouping method of beam splitting waveguide array, that is, S m Distribution function, so that the sideband suppression ratio of the far-field light intensity is maximized; A silicon-based optical phased array structure based on a calculation method for a silicon-based optical phased array structure with a high sideband suppression ratio comprises a laser (1), a coupled beam splitter (2), a phase modulator (3), a transmission waveguide (4) and a coupled grating (5), wherein the coupled beam splitter (2), the phase modulator (3), the transmission waveguide (4) and the coupled grating (5) are all integrated on a silicon dioxide substrate. The output light beam of the laser (1) enters the coupling beam splitter (2), the coupling beam splitter (2) splits the single-path light into multiple-path light, each split light beam simultaneously enters the phase modulator (3) for phase modulation, the transmission waveguide (4) connects the phase modulator (3) and the coupling grating (5), and the coupling grating (5) radiates the phase-modulated multiple-path light to the far field.

2. The calculation method of a silicon-based optical phased array structure with high sideband suppression ratio according to claim 1, characterized in that: The coupled beam splitter (2) is 1× N The beam splitting structure consists of a beam with a width of W 0 main waveguide and beam splitting waveguide array, the beam splitting waveguide array consists of N sub-waveguides, the sub-waveguide width is W 1, W 1 = W 0, N Is a positive integer.

3. The calculation method of a silicon-based optical phased array structure with high sideband suppression ratio according to claim 2, characterized in that: The beam splitting waveguide array N The sub-waveguide consists of a length of L i ( i = 1, 2, …, N ) is composed of a straight waveguide and an S-shaped Bezier waveguide, which are cascaded on the same side of the main waveguide. N The sub-waveguides are non-uniformly divided into M Group, then: ， in, m j For the j ( j = 1, 2, …, M ) The number of sub-waveguides in the group, M Is a positive integer.

4. The calculation method of a silicon-based optical phased array structure with high sideband suppression ratio according to claim 2, characterized in that: The phase modulator provides additional phase to the beam splitting waveguide array, and its gradient Δφ as follows: ， in, λ is the wavelength of the light source beam, N eff is the effective refractive index of the light beam propagating in the waveguide, D is the interval period of the output waveguide array, θ s is the scanning pointing angle of the optical phased array.

5. The calculation method of the silicon-based optical phased array structure with high sideband suppression ratio according to claim 4, characterized in that: The transmission waveguide (4) is a uniformly distributed array, and the number of sub-waveguides is N , the interval period of the output waveguide array is D = αλ ;in, α Array spacing factor.

6. The calculation method of a silicon-based optical phased array structure with high sideband suppression ratio according to claim 1, characterized in that: The coupled grating (5) is a sub-wavelength grating, and the grating period Λ satisfies the phase matching condition, which is as follows: ， in, λ is the wavelength of the light source beam, n p is the refractive index of the light beam in the exit space, N eff is the effective refractive index of the light beam propagating in the waveguide.

7. The calculation method of a silicon-based optical phased array structure with high sideband suppression ratio according to claim 1, characterized in that: The laser (1) is an off-chip light source. The laser (1) is a monochromatic light source for one-dimensional scanning and a broad-spectrum light source for two-dimensional scanning.

8. The calculation method of a silicon-based optical phased array structure with high sideband suppression ratio according to claim 1, characterized in that: N After the sub-waveguides are grouped, the average length of the straight waveguide in each group L m ( S m ) is greater than 0.5 μm .

Images