CN100483166C - Optical waveguide array electro-optic scanner based scanning beam ring compression method - Google Patents

Optical waveguide array electro-optic scanner based scanning beam ring compression method Download PDF

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CN100483166C
CN100483166C CNB2007100181897A CN200710018189A CN100483166C CN 100483166 C CN100483166 C CN 100483166C CN B2007100181897 A CNB2007100181897 A CN B2007100181897A CN 200710018189 A CN200710018189 A CN 200710018189A CN 100483166 C CN100483166 C CN 100483166C
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waveguide
optical waveguide
sidelobe
spacing
refractive index
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CN101078801A (en
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石顺祥
梁华伟
李家立
马琳
刘继芳
孙艳玲
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Xidian University
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Xidian University
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Abstract

The invention discloses a side lobe compression method for scanning beam based on optical waveguide array electro-optic scanner. Aiming at side lobe of beam of optical waveguide array electro-optic scanner with optical waveguide coupling, the method compresses side lobe of scanning beam generated by optical waveguide coupling by setting different optical waveguide core layer refraction and by setting irregular distribution of optical waveguide distance scanning beam generated by optical waveguide equal-distance is compressed. The process that that refraction of each waveguide core layer is set more or less than the refraction of adjacent waveguide core layer; the distance of each waveguide is set according to the rule that the distance increases by monotonic linearity or monotonic quadratic or monotonic cube; the setting parameter is simulated to obtain radiation intensity distribution when beam is not be scanned; additional primary phase of different waveguide is set again to carry out simulating calculation so as to obtain radiation intensity distribution when beam is scanned. The invention can decrease coupling between waveguides effectively, compress side lobe of scanning beam effectively and improve the ability for target detection.

Description

Scanning light beam sidelobe compression method based on optical waveguide array electro-optic scanner
Technical field
The present invention relates to laser technology field, specifically a kind of method of utilizing the scanning light beam sidelobe compression of the quick optical waveguide array electro-optic scanner that optical waveguide array realizes can be used for the beam flying in laser radar, laser guidance, laser display field.
Background technology
Along with the development of laser radar, laser guidance, laser display technology, the characteristic of laser scanning to be had higher requirement, the technical scheme of realization laser scanning has a variety of, as optical mechaical scanning, electropical scanning, acousto-optic scanning, optical phased array technology etc.
Optical mechaical scanning has been widely adopted in such as many systems such as infrared imagings, and particularly the development in recent years microelectron-mechanical scanning technique of getting up is more widely used this technology.The advantage of optical mechaical scanning is that sweep limit is big, optical loss is little, but because of there is inertia device in it, sweep velocity is slow, and its application is restricted.
Electric light, acousto-optic scanning are to utilize electric light, acoustooptic effect to change light beam in the spatial transmission direction.The advantage of these two kinds of scannings is that the scanning addressing speed is fast, controllability good, but traditional electric light, acousto-optic scanning are because control voltage height, sweep limit is little, optical loss is big, has directly influenced their practical application.
In recent years, optical phased array technology OPA becomes the focus of studying beam flying in the world gradually.The basic structure of Beam Control is to be made of several array elements, incides the phase delay of the light in each array element by control, makes light beam carry out spacescan.Simple in structure, in light weight, precise and stable, the controlled advantage of direction that optical phased array has can realize that multi-beam scans simultaneously by programmed control, and has dynamic focusing and defocus ability.For many years, numerous researchists study it.Wherein, people such as nineteen ninety-five Thomas are at " Programmable diffractive optical element using a multichannellanthanum-modified lead zirconate titanate phase modulator " (Opt.Lett., 20,1995, propose 1510-1512) based on the optical phased array design of plumbous lanthanum zirconium titanium sintered body PLZT and people such as McManamon in 1996 at " Optical Phased Array Technology " (Proc.IEEE, 84,1996,268～298) the compactness that proposes in based on nematic liquid crystal, the high-resolution optical phased array has been represented present two important research directions.These two kinds of optical phased arrays have bigger numerical aperture, but because the response speed of nematic liquid crystal is slow, has only the ms magnitude, thereby be difficult to well play a role in the application of high-velocity scanning; And PLZT is higher because of its modulation voltage, and driving power is complicated, makes range of application also be subjected to certain restriction.
People such as Hobbs are at " Laser Electro-Optic Phased Array Devices (LEOSPARD) " (IEEE Laser and Electro-Optics Society Conf.Proc., the notion of the phased beam flying of a kind of optical waveguide array electric light has been proposed 1989,94～95).Wherein, optical waveguide array electro-optic scanner as shown in Figure 1, but represented another important developing direction of practicability optical phased array, be subjected to people's attention, and carried out extensive studies.Under the situation of coupling of not considering between optical waveguide to the scan characteristic influence, we adopt " a kind of novel optical waveguide array electric light rapid scanner " (optics journal, 2002, the scan characteristic of the diffraction theory research optical phased array 1318-1322) shows, the optical waveguide array electro-optic scanner spatial field distributes except the main lobe that is used to scan, and also has some to influence the sidelobe of scan characteristic.Fig. 3 be by diffraction theory calculate as light wavelength lambda=0.85 μ m, the waveguide core layer thickness is optical waveguide width a=0.55 μ m, during optical waveguide spacing d=1.7 μ m, the light beam radiation characteristic of 10 layers of optical waveguide array.Fig. 3 (a) is that to scan be that the radiation light intensity normalization of scanning angle when being 0 ° distributes, the radiation light intensity normalization distribution when Fig. 3 (b) is 15 ° for scanning angle.
As seen from Figure 3, in the scanning process of optical waveguide array electro-optic scanner, sidelobe is very big to the scanning light beam properties influence, and it will cause sweep limit to reduce and will become the interference of detectable signal.According to the needs of practical application, must compress sidelobe.
Sidelobe compression ideally for not considering the coupling between optical waveguide has had the people that it has been carried out special discussion, as: phased array optical equipment and method, Chinese patent, application number: 97119771.7.This patent is being ignored under the prerequisite that is coupled between the optical waveguide, adopts the irregular location mode of optical waveguide spacing to study the sidelobe compression of optical phased array.But in real work, because the optical waveguide width and the optical waveguide spacing of optical waveguide array electro-optic scanner is all very little, thereby the coupling between optical waveguide can not be left in the basket to the influence of beam flying characteristic.If adopting the scan characteristic of simulation method-finite difference beam Propagation method research optical waveguide array electro-optic scanner will find, coupling between optical waveguide is very big to the influence of scan characteristic, in scanning process, except original main lobe and sidelobe, some other sidelobe appears also.Fig. 4 be utilize that finite difference beam Propagation method calculates when light wavelength lambda=0.85 μ m, waveguide core layer thickness a=0.55 μ m, optical waveguide spacing d=1.7 μ m, sandwich layer refractive index n 1=3.51, cladding index n 2=3.43 o'clock, the light beam radiation characteristic of 10 layers of optical waveguide array.Fig. 4 (a) is that scanning angle is that 0 ° radiation light intensity normalization distributes the radiation light intensity normalization distribution when Fig. 4 (b) is 15 ° for scanning angle when scanning.By Fig. 4 and Fig. 3 as seen, because the influence that is coupled between optical waveguide, great changes have taken place in spacescan optical field distribution characteristic, and sidelobe is more serious to the influence of scan characteristic, even might make target detection to carry out.Thereby for this optical waveguide array electro-optic scanner, the sidelobe of limited scanning light beam is a critical major issue to improve beam flying quality and target detection precision.Should be pointed out that this problem has universal significance for the optical phased array technology of similar structures.
The content of invention
The purpose of this invention is to provide scanning light beam sidelobe compression method based on optical waveguide array electro-optic scanner, considering under the situation about being coupled between optical waveguide, sidelobe to the optical waveguide array electro-optic scanner scanning light beam effectively compresses, to solve, influence the problem of detection accuracy in scanning light beam quality and the practical application because of the scanning light beam sidelobe is bigger.
The present invention is achieved in that
Know-why
1. by the unequal distribution of adjacent light waveguide core layer refractive index is set, reduce the coupling between optical waveguide, limited scanning light beam sidelobe.
According to " waveguide core layer refractive index different directional coupler research " (Central China University of Science and Technology's journal, 35 (Z1), 2007,30-33) theory, when adjacent light waveguide core layer refractive index was unequal, the propagation constant difference of its guided mode was bigger, coupling is very little between optical waveguide; For by the unequal light wave propagation constant mismatch problems that causes of refractive index, can be by the length of appropriate design optical waveguide, make that the phase differential between the different optical waveguides is the integral multiple of 2 π just in the output face, realize phase matching.Therefore, the unequal distribution of adjacent light waveguide core layer refractive index can be set, effectively reduce the coupling between optical waveguide, the compression sidelobe.
2. being provided with on the unequal basis of adjacent light waveguide core layer refractive index, further compress sidelobe by the irregular distribution of optical waveguide spacing.
Principle (the Suppression of sidelobes in thefar-field patterns of electro-optical waveguide array of the irregular distribution sidelobe compression of optical waveguide spacing, SPIE, 5279,2004,416-422) be:, and utilize electrooptical effect to control the output phase of different optical waveguides by the irregular distribution of optimal design optical waveguide spacing
Figure C200710018189D00081
Guarantee at spacescan angle θ sLast diffracted beam coherent phase is long, form the scanning main lobe, and it is long not satisfy coherent phase on other diffraction direction, reaches the purpose of sidelobe compression.
For the optical waveguide array electro-optic scanner of the irregular distribution of optical waveguide spacing, the distribution of amplitudes when the space radiation angle is θ is
In the formula, E 0Be the amplitude of corresponding single slit diffraction receiving screen center, α=π asin θ/λ, a is an optical waveguide thickness, and λ is a lambda1-wavelength, and N is the optical waveguide array number of plies, A jBe the light field amplitude of j layer optical waveguide, k is the wave number in the vacuum, x jBe the distance of j optical waveguide to first optical waveguide.
Situation (4 for the uniform irradiation optical waveguide array j=1), following formula can be reduced to
Figure C200710018189D00092
d j＝x j-x j-1 (3)
d jIt is the spacing of j optical waveguide and j-1 optical waveguide.Light distribution when correspondingly, the space radiation angle is θ is
Figure C200710018189D00093
I 0 = E 0 2 Accept the light intensity of screen center for corresponding single waveguide antenna light beam.
According to following formula, change d jSize promptly change x jDistribution, and control by electrooptical effect
Figure C200710018189D00095
Just can change the distribution of light intensity I (θ).When satisfying by optimal design at spacescan angle θ sOn, the diffracted beam coherent phase is long, form the scanning main lobe, and on other diffraction direction, it is long not satisfy coherent phase, reaches the purpose of sidelobe compression.
Refractive index by design adjacent light waveguide core layer does not wait distribution, has made the coupling between optical waveguide become very little, on this basis, by the irregular distribution of optimal design optical waveguide spacing, can further compress sidelobe again.
The technical thought that realizes the object of the invention is: at the optical waveguide array electro-optic scanner of considering to be coupled between optical waveguide, come limited scanning light beam sidelobe by changing the optical waveguide array structure, promptly by making the coupling between the unequal distribution reduction of adjacent light waveguide core layer refractive index optical waveguide, with limited scanning light beam sidelobe; By making the further limited scanning light beam of the irregular distribution of optical waveguide spacing sidelobe, thereby effectively improve the quality of scanning light beam, improve the ability of target detection.
Technical scheme 1
According to the requirement of optical waveguide material and metal-organic chemical vapor deposition equipment technology, each optical waveguide cladding index, optical waveguide width, optical waveguide length and lambda1-wavelength are set;
It is unequal that adjacent light waveguide core layer refractive index is set, to reduce the coupling between optical waveguide, limited scanning light beam sidelobe;
Each optical waveguide spacing is provided with according to dull linear the increase, with further limited scanning light beam sidelobe;
According to I ( θ ) = I 0 sin α α | Σ j = 1 N exp ( ikx j sin θ ) | 2 , Utilize Matlab software this parameter to be simulated not carried out beam flying be the radiation intensity distribution of scanning angle when being 0 °;
According to
Figure C200710018189D00102
The waveguide additive phase that causes owing to electrooptical effect is set, in the formula, j=2,3 ... 10, Be the additive phase of j waveguide, x jBe the distance of j waveguide to first waveguide, different scanning angle that the different sizes of p are corresponding, for certain scanning position of determining, p is a definite value;
According to
Figure C200710018189D00104
Utilize Matlab software to carry out the radiation intensity distribution of simulation trial when obtaining beam flying, in the formula, I 0Be the light intensity of corresponding single slit diffraction receiving screen center, α=π asin θ/λ, a is an optical waveguide thickness, and θ is the space radiation angle, and λ is a lambda1-wavelength, and N is the optical waveguide array number of plies, k is the wave number in the vacuum, x jBe the distance of j optical waveguide to first optical waveguide.
Technical scheme 2
According to the requirement of optical waveguide material and metal-organic chemical vapor deposition equipment technology, each optical waveguide cladding index, optical waveguide width, optical waveguide length and lambda1-wavelength are set
It is unequal that adjacent light waveguide core layer refractive index is set, and reduces the coupling between optical waveguide, the scanning light beam sidelobe that compression is caused by the coupling between optical waveguide,
Increase the spacing that rule is provided with each optical waveguide according to dull quadratic power or dull cube, further limited scanning light beam sidelobe;
According to I ( θ ) = I 0 sin α α | Σ j = 1 N exp ( ikx j sin θ ) | 2 , Utilize Matlab software that this parameter is simulated, do not carried out beam flying and be the radiation intensity distribution of scanning angle when being 0 °;
According to The waveguide additive phase is set, in the formula, j=2,3 ... 10,
Figure C200710018189D00113
Be the additive phase of j waveguide, x jBe the distance of j waveguide to first waveguide, different scanning angle that the different sizes of p are corresponding, for certain scanning position of determining, p is a definite value;
According to
Figure C200710018189D00114
Utilize Matlab software to carry out the radiation intensity distribution of simulation trial when having obtained beam flying, in the formula, I 0Be the light intensity of corresponding single slit diffraction receiving screen center, α=π asin θ/λ, a is an optical waveguide thickness, and θ is the space radiation angle, and λ is a lambda1-wavelength, and N is the optical waveguide array number of plies, k is the wave number in the vacuum, x jBe the distance of j optical waveguide to first optical waveguide.
The present invention is owing at first be provided with the refractive index and the different parameter of adjacent light waveguide core layer refractive index of each optical waveguide sandwich layer, and then the irregular distribution of each optical waveguide spacing is set, thereby can compress the scanning light beam sidelobe of the optical waveguide array electro-optic scanner of considering the coupling between optical waveguide well, greatly improved the quality of scanning light beam.
Description of drawings
Fig. 1 is the optical waveguide array electro-optic scanner instance graph that the present invention controls;
Fig. 2 is scanning light beam sidelobe compression process figure of the present invention;
Fig. 3 (a) does not consider the influence that is coupled between optical waveguide, and scanning angle is 0 ° of radiation intensity distribution figure when promptly not carrying out beam flying;
Fig. 3 (b) does not consider the influence that is coupled between optical waveguide, the radiation intensity distribution figure when scanning angle is 15 °;
Fig. 4 (a) considers the influence that is coupled between optical waveguide, and scanning angle is 0 ° of radiation intensity distribution figure when promptly not carrying out beam flying;
Fig. 4 (b) is the influence that is coupled between the consideration optical waveguide, the radiation intensity distribution figure when scanning angle is 15 °;
Fig. 5 (a) considers the influence that is coupled between optical waveguide, and it is unequal that adjacent light waveguide core layer refractive index is set, and the optical waveguide spacing equates, scanning angle is 0 ° of radiation intensity distribution figure when promptly not carrying out beam flying;
Fig. 5 (b) is the influence that is coupled between the consideration optical waveguide, and it is unequal that adjacent light waveguide core layer refractive index is set, and the optical waveguide spacing equates, the radiation intensity distribution figure when scanning angle is 15 °;
Fig. 6 (a) considers the influence that is coupled between optical waveguide, and it is unequal that adjacent light waveguide core layer refractive index is set, and the optical waveguide spacing adopts dull linear increase mode to be provided with, and scanning angle is 0 ° of radiation intensity distribution figure when promptly not carrying out beam flying;
Fig. 6 (b) is the influence that is coupled between the consideration optical waveguide, and it is unequal that adjacent light waveguide core layer refractive index is set, and the optical waveguide spacing adopts dull linear increase mode that the radiation intensity distribution figure when scanning angle is 15 ° is set;
Fig. 7 (a) considers the influence that is coupled between optical waveguide, and it is unequal that adjacent light waveguide core layer refractive index is set, and the optical waveguide spacing adopts dull quadratic power increase mode to be provided with, and scanning angle is 0 ° of radiation intensity distribution figure when promptly not carrying out beam flying;
Fig. 7 (b) is the influence that is coupled between the consideration optical waveguide, and it is unequal that adjacent light waveguide core layer refractive index is set, and the optical waveguide spacing adopts dull quadratic power increase mode that the radiation intensity distribution figure when scanning angle is 15 ° is set;
Fig. 8 (a) considers the influence that is coupled between optical waveguide, and it is unequal that adjacent light waveguide core layer refractive index is set, and the optical waveguide spacing adopts dull cube increase mode to be provided with, and scanning angle is 0 ° of radiation intensity distribution figure when promptly not carrying out beam flying;
Fig. 8 (b) is the influence that is coupled between the consideration optical waveguide, and it is unequal that adjacent light waveguide core layer refractive index is set, and the optical waveguide spacing adopts dull cube increase mode that the radiation intensity distribution figure when scanning angle is 15 ° is set.
Embodiment
With reference to Fig. 1, the optical waveguide array electro-optic scanner of the present invention's control comprises: optical waveguide sandwich layer, optical waveguide covering and control system, wherein, the covering effect of electrode of having held concurrently, be called electrode layer again, control system is a driving power, and it can export plurality of voltages as required.The basic functional principle of optical waveguide array electro-optic scanner: can on each electrode layer, necessary potential be set by control system, just can in optical waveguide, form needed electric field, thereby on optical waveguide array output cross section, form needed additive phase, and the additive phase that distributes according to certain rules can cause the deflection of output beam.
Utilize optical waveguide array electro-optic scanner shown in Figure 1 to carry out process such as Fig. 2 of the compression of scanning light beam sidelobe.
Embodiment 1
Select the optical waveguide array electro-optic scanner of forming by 10 optical waveguides for use, select for use AlGaAs optical waveguide material, select for use semiconductor laser to produce laser beam, the driving power of semiconductor laser adopts common power supply, control system adopts the driving power that can change output 10 road voltages fast, select for use template as the radiation laser beam receiving screen, select for use charge coupled device ccd to receive scanning light beam.
Step 1 is provided with the structural parameters and the lambda1-wavelength of optical waveguide array, and promptly cladding index is 3.43, and the optical waveguide width is 0.55 μ m, optical waveguide length 6000 μ m, and lambda1-wavelength is made as 0.85 μ m;
Step 2 according to the unequal rule of adjacent light waveguide core layer refractive index, is provided with optical waveguide sandwich layer refractive index, and promptly 10 optical waveguide sandwich layer refractive indexes alternately are 3.51 and 3.52 successively;
Step 3 is greatly d according to the linear monotone increasing of optical waveguide spacing j=d 2The rule variation of+c (j-2) is provided with each waveguide spacing, in the formula, and j=2,3,4 ... N, N are the waveguide number, d jBe the spacing of j waveguide and j-1 waveguide, d 2Be the distance between the 2nd waveguide and the 1st waveguide, c is the amplitude that the 2nd waveguide spacing increases with respect to the 1st waveguide spacing, i.e. d 2=1.7 μ m, d 3=1.9 μ m, d 4=2.1 μ m, d 5=2.3 μ m, d 6=2.5 μ m, d 7=2.7 μ m, d 8=2.9 μ m, d 9=3.1 μ m, d 10=3.3 μ m;
Step 4, according to I ( θ ) = I 0 sin α α | Σ j = 1 N exp ( ikx j sin θ ) | 2 , Utilize Matlab software that this parameter is carried out simulation trial, obtain the light intensity value of different spaces radiation angle, utilize these light intensity values to draw, do not carried out beam flying and be scanning angle radiation intensity distribution such as Fig. 6 (a) when being 0 °, in the formula, I 0Be the light intensity of single waveguide antenna light beam receiving screen center, α=π asin θ/λ, a is a duct thickness, and θ is the space radiation angle, and λ is a lambda1-wavelength, and N is the optical waveguide array number of plies, k is the wave number in the vacuum, x jBe the distance of j waveguide to first waveguide;
Step 5 is pressed
Figure C200710018189D00142
The waveguide additive phase that causes owing to electrooptical effect is set, in the formula, j=2,3 ... 10,
Figure C200710018189D00143
Be the additive phase of j waveguide, x jBe the distance of j waveguide to first waveguide, different scanning angle that the different sizes of p are corresponding, for certain scanning position of determining, p is a definite value;
Step 6, according to
Figure C200710018189D00144
Utilize Matlab software to carry out simulation trial, obtain the light intensity value of different spaces radiation angle, utilize these light intensity values to draw, radiation intensity distribution when obtaining carrying out beam flying such as Fig. 6 (b), in the formula, I 0Be the light intensity of corresponding single waveguide diffraction receiving screen center, α=π asin θ/λ, a is a duct thickness, and θ is the space radiation angle, and λ is a lambda1-wavelength, and N is the waveguide array number of plies, k is the wave number in the vacuum, x jBe the distance of j waveguide to first waveguide.
Embodiment 2
Select the optical waveguide array electro-optic scanner of forming by 10 optical waveguides for use, select for use AlGaAs optical waveguide material, select for use semiconductor laser to produce laser beam, the driving power of semiconductor laser adopts common power supply, control system adopts the driving power that can change output 10 road voltages fast, select for use template as the radiation laser beam receiving screen, select for use charge coupled device ccd to receive scanning light beam.
Step 1 is provided with the structural parameters and the lambda1-wavelength of optical waveguide array, and promptly cladding index is 3.43, and the optical waveguide width is 0.55 μ m, optical waveguide length 6000 μ m, and lambda1-wavelength is made as 0.85 μ m;
Step 2 according to the unequal rule of adjacent light waveguide core layer refractive index, is provided with optical waveguide sandwich layer refractive index, and promptly 10 optical waveguide sandwich layer refractive indexes alternately are 3.51 and 3.52 successively;
Step 3 is d according to dull increase of optical waveguide spacing quadratic power j=d 2+ c (j-2) 2Rule change each waveguide spacing be provided with, in the formula, j=2,3,4 ... N, N are the waveguide number, d jBe the spacing of j waveguide and j-1 waveguide, d 2Be the distance between the 2nd waveguide and the 1st waveguide, c is the amplitude that the 2nd waveguide spacing increases with respect to the 1st waveguide spacing, i.e. d 2=1.7 μ m, d 3=1.8 μ m, d 4=2.1 μ m, d 5=2.6 μ m, d 6=3.3 μ m, d 7=4.2 μ m, d 8=5.3 μ m, d 9=6.6 μ m, d 10=8.1 μ m;
Step 4, according to I ( θ ) = I 0 sin α α | Σ j = 1 N exp ( ikx j sin θ ) | 2 , Utilize Matlab software that this parameter is carried out simulation trial, obtain the light intensity value of different spaces radiation angle, utilize these light intensity values to draw, do not carried out beam flying and be scanning angle radiation intensity distribution such as Fig. 7 (a) when being 0 °, in the formula, I 0Be the light intensity of single waveguide antenna light beam receiving screen center, α=π asin θ/λ, a is a duct thickness, and θ is the space radiation angle, and λ is a lambda1-wavelength, and N is the optical waveguide array number of plies, k is the wave number in the vacuum, x lBe the distance of j waveguide to first waveguide;
Step 5 is pressed
Figure C200710018189D00161
The waveguide additive phase that electrooptical effect causes is set, in the formula, j=2,3 ... 10,
Figure C200710018189D00162
Be the additive phase of j waveguide, x jBe the distance of j waveguide to first waveguide, different scanning angle that the different sizes of p are corresponding, for certain scanning position of determining, p is a definite value;
Step 6, according to
Figure C200710018189D00163
Utilize Matlab software to carry out simulation trial, obtain the light intensity value of different spaces radiation angle, utilize these light intensity values to draw, radiation intensity distribution when obtaining carrying out beam flying such as Fig. 7 (b), in the formula, I 0Be the light intensity of corresponding single waveguide diffraction receiving screen center, α=π asin θ/λ, a is a duct thickness, and θ is the space radiation angle, and λ is a lambda1-wavelength, and N is the waveguide array number of plies, k is the wave number in the vacuum, x jBe the distance of j waveguide to first waveguide.
Embodiment 3
Select the optical waveguide array electro-optic scanner of forming by 10 optical waveguides for use, select for use AlGaAs optical waveguide material, select for use semiconductor laser to produce laser beam, the driving power of semiconductor laser adopts common power supply, control system adopts the driving power that can change output 10 road voltages fast, select for use template as the radiation laser beam receiving screen, select for use charge coupled device ccd to receive scanning light beam.
Step 1 is provided with the structural parameters and the lambda1-wavelength of optical waveguide array, and promptly cladding index is 3.43, and the optical waveguide width is 0.55 μ m, optical waveguide length 6000 μ m, and lambda1-wavelength is made as 0.85 μ m;
Step 2 is provided with optical waveguide sandwich layer refractive index according to the unequal rule of adjacent light waveguide core layer refractive index, and promptly 10 optical waveguide sandwich layer refractive indexes alternately are 3.51 and 3.52 successively;
Step 3, increasing according to the dull cube of optical waveguide spacing is d j=d 2+ c (j-2) 3Rule change each waveguide spacing be provided with, in the formula, j=2,3,4 ... N, N are the waveguide number, d jBe the spacing of j waveguide and j-1 waveguide, d 2Be the distance between the 2nd waveguide and the 1st waveguide, c is the amplitude that the 2nd waveguide spacing increases with respect to the 1st waveguide spacing, i.e. d 2=1.7 μ m, d 3=1.8 μ m, d 4=2.5 μ m, d 5=4.4 μ m, d 6=8.1 μ m, d 7=14.2 μ m, d 8=23.3 μ m, d 9=36 μ m, d 10=52.9 μ m;
Step 4, according to I ( θ ) = I 0 sin α α | Σ j = 1 N exp ( ikx j sin θ ) | 2 , Utilize Matlab software that this parameter is carried out simulation trial, obtain the light intensity value of different spaces radiation angle, utilize these light intensity values to draw, do not carried out beam flying and be scanning angle radiation intensity distribution such as Fig. 8 (a) when being 0 °, in the formula, I 0Be the light intensity of single waveguide antenna light beam receiving screen center, α=π asin θ/λ, a is a duct thickness, and θ is the space radiation angle, and λ is a lambda1-wavelength, and N is the optical waveguide array number of plies, k is the wave number in the vacuum, x jBe the distance of j waveguide to first waveguide;
Step 5 is pressed The waveguide additive phase that electrooptical effect causes is set, in the formula, j=2,3 ... 10,
Figure C200710018189D00173
Be the additive phase of j waveguide, x jBe the distance of j waveguide to first waveguide, different scanning angle that the different sizes of p are corresponding, for certain scanning position of determining, p is a definite value;
Step 6, according to Utilize Matlab software to carry out simulation trial, obtain the light intensity value of different spaces radiation angle, utilize these light intensity values to draw, radiation intensity distribution when obtaining carrying out beam flying such as Fig. 8 (b), in the formula, I 0Be the light intensity of corresponding single waveguide diffraction receiving screen center, α=π asin θ/λ, a is a duct thickness, and θ is the space radiation angle, and λ is a lambda1-wavelength, and N is the waveguide array number of plies, k is the wave number in the vacuum, x jBe the distance of j waveguide to first waveguide.
Compression effectiveness of the present invention can pass through Fig. 3～8 and describe in detail, promptly is benchmark with Fig. 5, compares with Fig. 3, Fig. 4, Fig. 6, Fig. 7, Fig. 8 respectively.
If optical waveguide sandwich layer refractive index alternately is 3.51 and 3.52, and the phase phasic difference of satisfying light field on the outgoing cross section is the integral multiple of 2 π, light wavelength lambda=0.85 μ m, waveguide core layer thickness a=0.55 μ m, optical waveguide spacing d=1.7 μ m, cladding index n 2=3.43 o'clock, 10 layers of optical waveguide array radiation intensity distribution that calculated by finite difference beam Propagation method as shown in Figure 5, wherein, Fig. 5 (a) is that the radiation light intensity normalization of scanning angle when being 0 ° distributes for scanning, the radiation light intensity normalization distribution when Fig. 5 (b) is 15 ° for scanning angle.
More as can be known, when scanning angle is 0 °, adjacent light waveguide core layer refractive index is set does not wait by Fig. 5 (a) and Fig. 4 (a), little to the influence of scan characteristic; More as can be known, when scanning angle is 15 °, adjacent light waveguide core layer refractive index is set does not wait by Fig. 5 (b) and Fig. 4 (b), the scanning light beam quality be improved significantly, but still have the remaining sides lobe.
By Fig. 5 (a) and (b) and Fig. 3 (a) and (b) more as can be known, when adjacent light waveguide core layer refractive index being set when unequal, consider not consider that the sidelobe that is coupled between optical waveguide is similar in the sidelobe that is coupled between optical waveguide and the diffraction theory.Hence one can see that, and the coupling between optical waveguide obtains bigger reduction, and sidelobe obtains compression.
By Fig. 6 (a) and (b) and Fig. 5 (a) and (b) more as can be seen, adopt the optical waveguide spacing dull linear increase to distribute can effectively compress sidelobe.
By Fig. 7 (a) and (b) and Fig. 5 (a) and (b) more as can be seen, adopt the dull quadratic power of optical waveguide spacing to increase to distribute and to compress sidelobe.
By Fig. 8 (a) and (b) and Fig. 5 (a) and (b) more as can be seen, adopt the dull cube of optical waveguide spacing to increase to distribute and to compress sidelobe.
More as can be seen, in the middle of these three kinds of distribution modes, the optical waveguide spacing adopts dull linear increase mode sidelobe compression effectiveness best by Fig. 6,7,8.
By Fig. 3～8 more as can be seen, by optimal design optical waveguide array structure, can under the actual conditions of considering coupling influence between optical waveguide, compress sidelobe well, promptly, adjacent light waveguide core layer refractive index do not wait the coupling that reduces between optical waveguide by being set, the compression sidelobe further compresses sidelobe by the irregular distribution of optical waveguide spacing is set.

Claims (8)

1. optical waveguide array electro-optic scanner sidelobe compression method comprises following process:
Requirement according to waveguide material and metal-organic chemical vapor deposition equipment is provided with each waveguide cladding index, duct width, waveguide length and lambda1-wavelength;
The refractive index of each waveguide core layer is set to be greater than or less than adjacent waveguide sandwich layer refractive index, to reduce the coupling between waveguide, limited scanning light beam sidelobe;
Each waveguide spacing is provided with according to linear increase of dullness, to compress the sidelobe that equidistantly causes owing to waveguide;
According to I ( θ ) = I 0 sin α α | Σ j = 1 N exp ( ikx j sin θ ) | 2 , Utilize Matlab software that this parameter is simulated radiation intensity distribution when not carried out beam flying, this light distribution promptly is the radiation intensity distribution of scanning angle when being 0 °;
Increase the additional initial phase that different waveguide is set according to dullness Different increase slope correspondences different scanning angles, according to
Figure C200710018189C00023
Utilize Matlab software to carry out the radiation intensity distribution of simulation trial when having obtained beam flying,
In the formula, the light distribution when I (θ) is θ for the space radiation angle, I 0Be the light intensity of corresponding single slit diffraction receiving screen center, α=π asin θ/λ, a is a duct thickness, and θ is the space radiation angle, and λ is a lambda1-wavelength, and N is the waveguide array number of plies, k is the wave number in the vacuum, x jBe the distance of j waveguide to first waveguide.
2. optical waveguide array electro-optic scanner sidelobe compression method according to claim 1, the refractive index that it is characterized in that each waveguide core layer is by n i≠ n I-1And n i≠ n I+1Be provided with, in the formula, n iBe the refractive index of i waveguide, i=2,3 ... N-1, N are the waveguide number, n I-1With n I+1Can equate also can be unequal.
3. optical waveguide array electro-optic scanner sidelobe compression method according to claim 1 is characterized in that each waveguide spacing is provided with according to dull linear the increase, is by d j=d 2The rule of+c (j-2) changes and carries out, in the formula, and j=2,3,4 ... N, N are the waveguide number, d jBe the spacing of j waveguide and j-1 waveguide, d 2Be the distance between the 2nd waveguide and the 1st waveguide, c is the amplitude that the 2nd waveguide spacing increases with respect to the 1st waveguide spacing.
4. optical waveguide array electro-optic scanner sidelobe compression method according to claim 1 is characterized in that the refractive index setting of each waveguide core layer, alternately is made as 3.51 and 3.52 for gallium aluminium arsenic material.
5. optical waveguide array electro-optic scanner sidelobe compression method comprises following process:
Requirement according to waveguide material and metal-organic chemical vapor deposition equipment is provided with each waveguide cladding index, duct width, waveguide length and lambda1-wavelength;
The refractive index of each waveguide core layer is set to be greater than or less than adjacent waveguide sandwich layer refractive index, to reduce the coupling between waveguide, limited scanning light beam sidelobe;
Increase the spacing that rule is provided with each waveguide according to dull quadratic power or dull cube, to compress the sidelobe that equidistantly causes owing to waveguide;
According to I ( θ ) = I 0 sin α α | Σ j = 1 N exp ( ikx j sin θ ) | 2 , Utilize Matlab software that this parameter is simulated, the radiation intensity distribution when not carried out beam flying;
Increase the additional initial phase that different waveguide is set according to dullness Different increase slope correspondences different scanning angles, according to
Figure C200710018189C00033
Utilize Matlab software to carry out the radiation intensity distribution of simulation trial when having obtained beam flying,
In the formula, the light distribution when I (θ) is θ for the space radiation angle, I 0Be the light intensity of corresponding single slit diffraction receiving screen center, α=π asin θ/λ, a is a duct thickness, and θ is the space radiation angle, and λ is a lambda1-wavelength, and N is the waveguide array number of plies, k is the wave number in the vacuum, x jBe the distance of j waveguide to first waveguide.
6. optical waveguide array electro-optic scanner sidelobe compression method according to claim 5 is characterized in that each waveguide spacing increases setting according to dull quadratic power, is by d j=d 2+ c (j-2) 2Rule changes and carries out, in the formula, and j=2,3,4 ... N, N are the waveguide number, d jBe the spacing of j waveguide and j-1 waveguide, d 2Be the distance between the 2nd waveguide and the 1st waveguide, c is the amplitude that the 2nd waveguide spacing increases with respect to the 1st waveguide spacing.
7. optical waveguide array electro-optic scanner sidelobe compression method according to claim 5 is characterized in that each waveguide spacing increases setting according to dull cube, is by d j=d 2+ c (j-2) 3Rule changes and carries out, in the formula, and j=2,3,4 ... N, N are the waveguide number, d jBe the spacing of j waveguide and j-1 waveguide, d 2Be the distance between the 2nd waveguide and the 1st waveguide, c is the amplitude that the 2nd waveguide spacing increases with respect to the 1st waveguide spacing.
8. optical waveguide array electro-optic scanner sidelobe compression method according to claim 5 is characterized in that the refractive index setting of each waveguide core layer, alternately is made as 3.51 and 3.52 for gallium aluminium arsenic material.
CNB2007100181897A 2007-07-05 2007-07-05 Optical waveguide array electro-optic scanner based scanning beam ring compression method Expired - Fee Related CN100483166C (en)

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