JPH012022A - light deflection device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an optical deflection device that generates surface acoustic waves in an optical waveguide and deflects guided light by the diffraction action of the surface acoustic waves. The present invention relates to an optical deflection device that deflects two light beams at the same time so that it can be used for parallel recording or reading of two images.

(Prior Art) As shown in Japanese Patent Application Laid-Open No. 61-183826, light is incident on an optical waveguide made of a material through which surface acoustic waves can propagate, and the guide propagates within the optical waveguide. A surface acoustic wave is generated in the direction intersecting the wave light, the guided light is Bragg diffracted by the surface acoustic wave, and the diffraction angle (deflection angle) of the guided light is continuously changed by continuously changing the frequency of the surface acoustic wave. A light deflection device that changes the direction of the light is known. Such optical deflection devices include, for example, mechanical optical devices such as galvanometer mirrors and polygon mirrors, EOD (electro-optic optical deflectors), and A
Compared to optical deflectors that use optical deflection elements such as OD (acousto-optic optical deflectors), they have the advantage of being smaller and lighter, and are highly reliable as they do not have mechanical moving parts. .

(Problems to be Solved by the Invention) However, the above-described optical deflection device has a problem in that it is difficult to obtain a large deflection angle.

In other words, in an optical deflection device using this optical waveguide, the optical deflection angle is approximately proportional to the frequency of the surface acoustic waves, so in order to obtain a large deflection angle, it is necessary to increase the frequency of the surface acoustic waves to an extremely high value. It will be necessary to change. Furthermore, in addition to changing the frequency of the surface acoustic waves over a wide band in this way, in order to satisfy the Bragg condition, the traveling direction of the surface acoustic waves is continuously changed (steering). It is necessary to control the angle of incidence on the

In order to meet the above requirements, for example,
1-183626, a plurality of interdigitated electrode pairs (IDT) generate surface acoustic waves whose frequencies change in different bands.
An optical deflection device has been proposed in which IDTs are arranged such that surface acoustic waves are generated in different directions, and each IDT is operated by switching.

However, the optical deflection device with the above configuration has a problem in that the diffraction efficiency decreases around the crossover frequency of the surface acoustic waves emitted by each IDT, so the amount of light of the deflected light beam fluctuates depending on the deflection angle. occurs.

Even with the above configuration, the IDT having a portion with a high deflection angle must be configured to generate surface acoustic waves of extremely high frequency. This point will be explained below with specific examples. If the incident angle of the guided light with respect to the traveling direction of the surface acoustic wave is θ, the deflection angle of the guided light due to the acousto-optic interaction between the surface acoustic wave and the guided light is δ
is δ-2θ. If the wavelength and effective refractive index of the guided light are λ and Ne, and the wavelength, frequency, and velocity of the surface acoustic wave are Δ, f, and v, respectively, then 2 θ −2 sin −1 (λ/2Ne φ A) λ/Ne 11A −λ·f/Ne −v (1). Therefore, the deflection angle range △(2θ) is △(2θ) − Δf・λ
/Ne*v. Here, for example, λ-0,78μas Ne-2
, 2, the deflection angle range Δ as v −350017L/S
(2θ) −10°, the frequency range of surface acoustic waves, that is, the frequency band Δ of the high frequency applied to the IDT.
f −1,72 GHz is required. If this frequency band is set to one octave so as not to be affected by the second-order diffracted light, the center frequency is fO-2, 57 GHz.

The maximum frequency is f2-3.43 GHz. The period of IDT that obtains this maximum frequency f2 is Δ-1.02 μm,
The line width of the IDT electrode finger is W-A/4-0.255 μm.

In the photolithography method and electron beam lithography, which are common techniques for forming IDTs, the current line width limits are approximately 0.8 μm and 0.5 μm, respectively, and therefore IDTs with extremely small line widths as described above is difficult to realize. Furthermore, even if such a fine IDT could be formed in the future, a driver that generates a high frequency of about 3.43 GHz would be difficult to manufacture and extremely expensive, and such a fine IDT would require a high voltage. It becomes difficult to apply. Furthermore, if the frequency of the surface acoustic wave is increased as described above, the wavelength will naturally become shorter, so the surface acoustic wave will be more easily absorbed by the optical waveguide, resulting in a decrease in diffraction efficiency.

On the other hand, the literature
son on C1rcu1ts and Syst
ems, vol, CAS-28, No.

12, p1072 [Guided-Wave
AcoustoopticBragg Module
ators for Wide-Band Inte
rated 0ptic Cosmunicatl
ons and Slgnal Pr.

cesslng ] by C, S, TSA I, as mentioned above, multiple IDTs are not switched, but one IDT is a curved finger whose electrode finger line width changes continuously and each electrode finger has an arc shape. An optical deflection device configured as a chirped IDT is shown in which the frequency and traveling direction of surface acoustic waves are continuously changed over a wide range using this single IDT. In such a configuration, the problem of the amount of light beam fluctuating depending on the deflection angle as described above can be solved, but the problem remains that the frequency of the surface acoustic wave must be set extremely high. , which causes exactly the same problem as described above.

On the other hand, when reproducing and recording medical images, for example, there is a desire to record two images with different enlargement ratios and image processing conditions side by side on one recording medium. The optical deflection device described above can of course be used in an optical scanning recording device that records an image as described above by scanning a light beam on a photosensitive material.
It can also be used to record images in parallel.

In other words, if the deflection angle range of the light beam by this optical deflection device is divided into two, and the light beam is modulated within each divided deflection angle range based on a different image signal, two images will be lined up on the photosensitive material. will be recorded.

Furthermore, it is also possible to configure an optical scanning reading device that reads two images simultaneously by using the optical deflection device as described above. In other words, in this case, a read image signal obtained by scanning a light beam over a read document on which two images are recorded and photoelectrically detecting emitted light, reflected light, etc. from the document, By separately extracting each divided deflection angle range, two sets of image signals each carrying one image are obtained.

However, as mentioned earlier, in this type of optical deflection device, it is difficult to obtain a large deflection angle range;
When images are recorded or read in parallel, the deflection angle range of the light beam used to record or read each image becomes even smaller by dividing a relatively small deflection angle range into two. Therefore, with such an image recording or reading method, only small-sized images can be recorded or read.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical deflection device that can be used for parallel recording or reading of two images, and that can widen the range of light beam deflection angles for recording or reading each image. It is something to do.

(Means for Solving the Problems) The first optical deflection device of the present invention allows guided light to travel within an optical waveguide formed of a material through which surface acoustic waves can propagate, as described above, and In an optical deflection device configured to diffract and deflect a wave using a surface acoustic wave, the first surface propagates in a direction intersecting the optical path of the first guided light guided in the optical waveguide and diffracts and deflects the guided light. A first surface acoustic wave generating means for generating an elastic wave in an optical waveguide; a second surface acoustic wave generating means for generating two surface acoustic waves in the optical waveguide; are arranged so as to scan over a predetermined surface without overlapping each other.

Further, the second optical deflection device of the present invention includes, in addition to the first surface acoustic wave generating means and the second surface acoustic wave generating means, the first guiding light diffracted by the first surface acoustic wave. The first waveguide light travels in a direction intersecting the optical path of the wave light,
Diffraction in a direction that further amplifies the f-direction due to the diffraction,
third surface acoustic wave generating means for generating a third surface acoustic wave to be deflected in the optical waveguide; and a third surface acoustic wave generating means for generating a third surface acoustic wave to be deflected in the optical waveguide; and the second waveguide light,
and fourth surface acoustic wave generating means for generating in the optical waveguide a fourth surface acoustic wave that is diffracted and deflected in a direction that further amplifies the deflection due to the diffraction, and the first and third surface acoustic wave generation means are provided. The wave number vectors of the first guided light before and after being diffracted by the first surface acoustic wave are kl+lk2, and the wave number vector of the first guided light diffracted by the third surface acoustic wave is l, respectively.
k3, the wave number vector of the first and third surface acoustic waves is IKl
, lk2, lkl + IKl ""lk
2 1) The frequency and traveling direction of the first and third surface acoustic waves are continuously changed while satisfying the following conditions: c2+1K2-1, respectively, and the second and fourth surface acoustic waves are generated. The means also sets the wave number vectors of the second guided light before and after being diffracted by the second surface acoustic wave to lk4. lk,, the wave number vector of the second waveguide light diffracted by the fourth surface acoustic wave is 1
6, the wave number vectors of the second and fourth surface acoustic waves are lk3
．． [When K, lk4 +IK3-1)c.

1, the frequencies and traveling directions of the second and fourth surface acoustic waves are continuously changed while satisfying the following conditions: 1.2.3 and 4. surface acoustic wave generation means,
The present invention is characterized in that the first and second guided light beams emitted from the optical waveguide are arranged so as to scan a predetermined surface without overlapping each other.

The above-mentioned surface acoustic wave generating means 1.2.3 and 4 are, for example, inclined finger chirped interdigitated electrode pairs in which the electrode finger spacing changes stepwise and the direction of each electrode finger changes stepwise. (T 1lted - Finger Chirpe
d IDT) and a driver that applies an alternating voltage whose frequency changes continuously to this electrode pair.

(Function) When a light beam is deflected by the first optical deflection device of the present invention, which includes the first surface acoustic wave generation means and the second surface acoustic wave generation means arranged as described above, the light beam is emitted from the optical waveguide. Since the two light beams scan separate locations on the predetermined surface (that is, the surface to be scanned), separate images can be recorded or read by each beam.

In this case, each light beam is deflected by a separate surface acoustic wave, so that the entire range of deflection angles achieved by each surface acoustic wave is available for recording or reading out an image.

The above also applies to the second optical deflection device of the present invention. Furthermore, in this second optical deflection device, the first (second) guided light that has been deflected by the first (second) surface acoustic wave is deflected again by the third (fourth) surface acoustic wave. Therefore, the deflection angle range for recording or reading one image is further expanded than that of the first optical deflection device.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 shows an embodiment of the first optical deflection device of the present invention. This optical deflection device 10 includes an optical waveguide 12 formed on a substrate 11 and a linear diffraction grating for light beam incidence formed on the optical waveguide 12.
ing coupler (hereinafter referred to as LGC)13
, LGC14 for light beam emission, and these LGCs
A pair of first and second tilted chirped interdigitated electrodes (Tilted - Finger Chirpe
dInter D 1g1tal T trans
ducer, hereinafter referred to as inclined finger chirp IDT>
17.18, and a high frequency amplifier 19.1 that applies a high frequency alternating voltage to each of these inclined finger chirp IDTs 17.18 in order to generate the surface acoustic waves 15.1B.
9° and sweepers 20, 20° that continuously change (sweep) the frequency of the voltage.

In this embodiment, as an example, the substrate 11 has LiNbO
The optical waveguide 12 is formed by using three wafers and providing a Ti diffusion film on the surface of the wafer. Note that substrate 1
Other than that, a crystalline substrate made of sapphire, SL, etc. may be used as the material. Furthermore, the optical waveguide 12 is not limited to the above-mentioned Ti diffusion, but may also be formed by sputtering, vapor depositing, or the like other materials on the substrate 11. Regarding optical waveguides, for example, T. Tamir (T, Tam1r)
“Integrated Obtics” (ed.)
rated 0rties) J () Bix in Applied Physics (Topics
in Applied Physics) Volume 7)
Springer -
(1975); "Optical Integrated Circuits" by Nishihara, Haruna, and Suhara, published by Ohmsha (1985).In the present invention, any of these known optical waveguides may be used as the optical waveguide 12. can also be used.

However, this optical waveguide 12 must be formed of a material such as the above-mentioned Ti diffusion film that can propagate surface acoustic waves, which will be described later. Further, the optical waveguide may have a laminated structure of two or more layers.

The inclined finger chirp IDT17.18 is, for example, an optical waveguide 1.
A positive electron beam resist is applied to the surface of 2, an Au conductive thin film is further deposited on top of it, an electrode pattern is drawn with an electron beam, the Au thin film is peeled off and developed, and then a Cr thin film and an A1 thin film are deposited. After that, it can be formed by performing lift-off in an organic solvent. Incidentally, when the substrate 11 and the optical waveguide 12 are made of a piezoelectric material, the inclined finger chirp IDT 17.18 generates a surface acoustic wave 15.1B even if it is installed directly inside the optical waveguide 12 or on the substrate 11.
However, if this is not the case, a piezoelectric thin film made of, for example, ZnO may be formed on a part of the substrate 11 or the optical waveguide 12 by vapor deposition, sputtering, etc., and the IDT 17.1B may be installed there. .

The deflected light beams L and L' are emitted toward the LGC 13 from light sources 21 and 21', such as semiconductor lasers, for example. These light beams LSL' (parallel beams) are taken into the optical waveguide 12 by the LGC 13 and guided within the optical waveguide 12, respectively.

Note that when the light beams L and L' are divergent beams, L
Instead of G C13, a focusing diffraction grating (Focus
lgG rating Coupler: F G
C), the divergent beam can be made into a parallel beam by this FCC and introduced into the optical waveguide 12. The first waveguide light guided in the optical waveguide 12 undergoes diffraction (B rag diffraction). And as mentioned above, the first
Since the frequency of the alternating voltage applied to the inclined finger chirp IDT 17 changes continuously, the frequency of the first surface acoustic wave 15 changes continuously. As is clear from equation (1) above, the guided light L diffracted by the surface acoustic wave 15
Since the deflection angle of 2 is approximately proportional to the frequency of the surface acoustic wave 15, as the frequency of the surface acoustic wave 15 changes as described above, the guided light L2 is continuously deflected as shown by arrow A. This guided light L2 is emitted to the outside of the optical waveguide 12 by the LGC14. In this way, the optical waveguide 12
The light beam L4 emitted to the outside scans the surface to be scanned 30 one-dimensionally.

The second guided light L1° guided in the optical waveguide 12 also undergoes diffraction (B rag diffraction). Then, since the frequency of the alternating voltage applied to the second tilted finger chirp IDT1g is swept in the same way as in the first tilted finger chirp IDT17, the diffracted waveguide light L2° is continuous as shown by arrow B. to be biased towards This guided light L2° is also L G
The light is emitted to the outside of the optical waveguide 12 by C14.

In this way, the light beam L, j emitted outside the optical waveguide I2
scans the surface to be scanned 30 one-dimensionally.

The first and second inclined finger chirp IDTs 17 and 18 cause the light beams La and L4' emitted from the optical waveguide 12 to
As shown in FIG. 2, they are arranged parallel to each other without overlapping each other on the surface to be scanned 30. Therefore, on the surface to be scanned 30, main scanning lines are formed separately by the light beams L4 and L4°. Therefore, if the surface to be scanned 30 is moved in a direction substantially perpendicular to the main scanning direction (in the direction of arrow Y) by a known sub-scanning means (not shown), each different area of the surface to be scanned 30 will be light beam L,
,L,' is scanned two-dimensionally.

Therefore, when recording an image using this optical deflection device 10 (in this case, the surface to be scanned 30 is a photosensitive material), the light beams L and L' incident on the optical deflection device 10 are
If synchronized with the deflection timing and modulated based on a separate image signal, the scanned surface 30. Images carried by these image signals are recorded in parallel on the top. On the other hand, when reading an image using this optical deflection device 10 (in this case, the scanned document if [I30 is a reading document on which two images are recorded), the light beams L, , L,'
If the emitted light, reflected light, or transmitted light generated in parallel from a location on the scanned surface 30 that has been scanned is independently detected by separate photoelectric reading means, two sets of image signals each carrying the above-mentioned images are obtained. can get.

In this optical deflection device IO, two light beams for recording or reading each image are connected to the first and second light beams, respectively.
Since the deflection is performed by the second surface acoustic waves 15, 16, the deflection angle range for each individual image is the same as when recording or reading one image with one light beam.

In the embodiment described above, as shown in FIG.
The scanning start point L of the light beam L, , L, ° on the scanned surface 30
s and Ls' are made to be close to each other, but depending on the arrangement of the IDTs 17 and 18 and the way of sweeping the alternating voltage frequency applied to them, the scanning end of the light beam L4%L4° can be changed as shown in Fig. 3. The light beams L, , L, ° can be placed close to each other, or as shown in Figure 4.
It is also possible to make one scanning start end and the other scanning end close to each other.

Next, with reference to FIG. 5, a second embodiment of the optical deflection device of the present invention will be described. In this FIG. 5, elements equivalent to those in FIG. 1 are given the same numbers, and explanations thereof will be omitted unless particularly necessary. In this optical deflection device 50, the first inclined finger chirp IDT
A third slanted finger chirp IDT 27 is provided adjacent to the slanted finger chirp IDT 17, and a fourth slanted finger chirp IDT 28 is provided adjacent to the second slanted finger chirp IDTL8.

As described above, the guided light L2 diffracted and deflected by the first surface acoustic wave 15 is transmitted to the third inclined finger chirp IDT 27.
Due to the acousto-optic interaction with the third surface acoustic wave 25 emitted from the surface acoustic wave 25, the deflection is diffracted in a direction that further amplifies the deflection. The frequency of the alternating voltage applied to the third tilted finger chirp IDT 27 is swept in the same way as in the first tilted finger chirp IDT 17, and therefore the third surface acoustic wave 25 is also similar to the first surface acoustic wave 15. Since the frequency changes continuously, the guided light L3 after passing through the third surface acoustic wave 25 is continuously deflected as shown by arrow C.

The guided light L2° diffracted and deflected by the surface acoustic wave 16 of measure 2 further amplifies the deflection due to acousto-optic interaction with the fourth surface acoustic wave 2B emitted from the fourth inclined finger chirp IDT 28. diffraction in the direction of Fourth
The frequency of the alternating voltage applied to the tilted finger chirp IDT 2B is swept in the same manner as in the second tilted finger chirp IDT 18, and therefore the fourth surface acoustic wave 26 also has a frequency similar to that of the second surface acoustic wave 16. changes continuously, so the guided light L3 after passing through the fourth surface acoustic wave 26
1 is continuously deflected as shown by the arrow. The guided light beams L3 and L31 thus deflected are emitted to the outside of the optical waveguide 12 by the LGC 14. Optical waveguide 1
2 The light beam L, , L, ° emitted to the outside is the scanned surface 3
Scan over 0 one-dimensionally.

In this device, the 1.2.3 and 4 inclined finger chirps IDTl7, I8.27 and 28 ensure that the light beams L, , L,'' emitted outside the optical waveguide 12 do not overlap each other on the scanned surface 30. Therefore, on the scanning surface 3o, main scanning lines are formed separately by the light beams L and L4'.

Therefore, when using this optical deflection device 50, it is possible to record or read two images in parallel in the same manner as when using the optical deflection device 10 described above.

Next, the light beams L4 and Llo emitted from the optical waveguide 12
The deflection angle ranges (that is, the deflection angle ranges of the guided light beams L3 and L3') Δδ and Δδ° will be explained with reference to FIG. Note that in this example, the first and third inclined finger chirps I
With respect to DT17.27, the second and fourth inclined finger chirp IDTs 1g and 28 have the same configuration (the arrangement is symmetrical), and voltages are applied to each in the same way. Deflection angle range △δ of beam L4
Let's go about it. FIG. 6 shows the first inclined finger chirp ID
The detailed shape and arrangement state of T17 and the third inclined finger chirp IDT27 are shown. As shown in the figure, in each of the first slanted finger chirp IDT 17 and the third slanted finger chirp IDT 27, the interval between the electrode fingers changes stepwise at a constant rate of change, and the direction of each electrode finger also changes stepwise at a constant rate of change. It is designed to change over time. First tilted finger chirp IDT17 and third tilted finger chirp ID
Both T27 are arranged so that the one with the narrower spacing between the electrode fingers (the upper end in the figure) is located on the guided light side, and as the frequency of the applied voltage is swept as described above, the upper end has the maximum frequency. fz-2GH2, and the lower end generates a surface acoustic wave with a minimum frequency fl-IGHz of 15.25. and the first tilted finger chirp IDT
17 has a shape in which the electrode fingers at the upper end and the lower end are inclined by 3" relative to each other, the electrode fingers at the upper end form an angle of 6" with respect to the traveling direction of the guided light L1, and the electrode fingers at the lower end form an angle of 3". They are arranged at an angle of . On the other hand, the tilted finger chirp IDT 27 of the third option has a shape in which the electrode fingers at the upper end and the lower end are inclined by 9'' to each other, and the electrode fingers at the upper end form an angle of 18'' with respect to the traveling direction of the guided light L1. The electrode finger at the bottom end is 9°
are arranged to form an angle. Note that the ground electrodes of both inclined finger chirp IDT17.27 may be integrated with each other. Also, the tilted finger chirp I mentioned above
DT is explained in detail in, for example, the above-mentioned literature by C.S. and TSAI.

2 GHz surface acoustic waves 15. from the first inclined finger chirp IDT17 and the third inclined finger chirp IDT27.
When the light beam 25 is emitted, the diffraction state of the light beam becomes the state shown by ■ in FIG. That is, in this case, the guided light L1 is incident on the 2 GHz surface acoustic wave 15 at an incident angle of 6 degrees, and this angle satisfies the Bragg condition. That is, the wave number vectors of the guided light L1 and the diffracted guided light L2 are Iki, lc2, and the wave number vector of the surface acoustic wave 15, respectively.
When IK is 1, as shown in FIG. 7 (1), it becomes +1-2. In other words, the traveling direction of the diffracted waveguide light L2 is the direction of the vector fk2 (deflection angle δ-2θ-1
2'). At this time, the 2 GHz surface acoustic wave 25 is transmitted to the electrode finger at the upper end of the third inclined finger chirp IDT 27 in FIG.
The incident angle of the guided light L2 to the surface acoustic wave 25 is also 6 degrees, and the surface acoustic wave 25 is the same as the surface acoustic wave 15. Since it is a wavelength, it satisfies the Bragg condition. That is, the guided light L after being diffracted by the surface acoustic wave 25
If the wave number vector of 3 is 1 and the wave number vector of surface acoustic wave 25 is IK2, then 2 is obtained as shown in Fig. 7 (1).
+ [K2 Liao l1C3.

From the above state, the frequency of surface acoustic wave 15.25 is IGH
It is gradually lowered to z. Each wave number vector lK of surface acoustic waves 15.25! , the size of IK2 l[xl, to 11!
+ is 2π/A if its wavelength is A, so
After all, it is proportional to the frequency of the surface acoustic wave 15.25. Therefore, when the frequency of the surface acoustic wave 15.25 is IGHz, the wave number vector 1 of the surface acoustic wave 15.25 is 1, IKz
The magnitude is 1/2 of that when the frequency is 2 GHz.

Further, in this case, the traveling directions of the surface acoustic waves 15 and 25, that is, the directions of the wave number vectors IK and IKz are IG
As described above, the electrode finger portions of the first tilted finger chirp IDT 17 and the third tilted finger chirp IDT 27 excite the surface acoustic wave 15.25 of 2 GHz.
3° and 9° to the electrode finger part that excites 25, respectively.
Since it is tilted, the wave number vector IKl of the 2 GHz surface acoustic wave is 15.25.

[Changes of 3° and 9″ from the direction of K2. Also, the direction of the seventh
In Figure (1), since azb, the surface acoustic wave 1
Wave number vector [K1 when the frequency of 5.25 is IGHz
, IKz are as shown in FIG. 7(2).

As explained above, the frequency of the surface acoustic wave 15.25 is I
Even in the case of GHz, the above-mentioned 1 holds the following relationship: +1K1-1kHz lk2+IK2-1 and 3.

The magnitude of the wave number vector Ik, 1 to 11, is n·2π/λ (n is the refractive index), where λ is the wavelength of the guided light L1, and this wavelength is the same for the guided lights L 2 and L 3. Therefore, in the end, 1 l = l [kz l = 1lk3 l
The wave number vector IK1 of the -blade surface acoustic wave 15 is 2π/A when its wavelength is 8, and this wavelength is always equal to the wavelength of the surface acoustic wave 25, so l[Kt l = l[K2 1. In addition, the directions of the wave number vectors IK1 and IKz are such that the frequency of the surface acoustic wave 15.25 is 2G, as explained earlier.
When changing from Hz to IGHz, each changes at its own constant rate of change. Therefore, the surface acoustic wave 15.25
While the frequency of changes from 2 GHz to IGHz as described above, the above-mentioned relationship of Ikl + [K, - 2 rkz + [KZ - [k3] always holds, and the Bragg condition between the guided light L1 and the surface acoustic wave 15 is satisfied. , the Bragg condition between the guided light L2 and the surface acoustic wave 25 is always satisfied.

As is clear from the above explanation, surface acoustic waves 15.25
When the frequency of is 2 GHz and IGHz, the traveling direction of the guided wave L3 diffracted twice is 3 in the vector of Fig. 7 (1) and 3 in the direction of the vector in Fig.
■The direction indicated by ''), and the difference is 24-12-12°
It is. In other words, with this device, a wide deflection angle range of Δδ - 12'' can be obtained.Incidentally, one device whose frequency varies from IGHz to 2GHz (the frequency band is set to one octave so as not to be affected by the second-order diffracted light) If the optical beam is deflected only by surface acoustic waves, the deflection angle range will be 66, which is 1/2 of the above value.

As mentioned above, in this example, the second and fourth inclined finger chirp IDTs 18.28 have the same configuration as the first and third inclined finger chirp IDTs 17.27 (the arrangement is symmetrical), and Since the voltages are applied in the same manner as each other, the wave number vector of the second guided light 5' before being diffracted by the second surface acoustic wave 16 becomes The wave number vector of the second guided light L3 is 5, and the wave number vector of the second guided light L3' diffracted by the fourth surface acoustic wave 26 is I.
k6, the wave number vectors of the second and fourth surface acoustic waves 16.26 [K3. [K, then [k, +IK3-1k.

The relationship k5 +rK4-nc6 is always satisfied, and the guided light has a deflection angle range of 3° △
δ° is 12′, which is equal to the deflection angle range Δδ of the guided light L3.

As described above, in this optical deflection device 50, the respective deflection angle ranges Δδ and Δδ' of the light beams L4, L, and degrees are different from each other as in the first optical deflection device 10 described above.
Compared to the case where L' is each deflected by one surface acoustic wave 15,16, this is essentially doubled. Therefore, by using this optical deflection device 50, a wider beam scanning width can be secured than when using the optical deflection device 10, and it is possible to record or read a larger size image.

Note that if the frequency of the surface acoustic wave 15.25 is made even lower than IGHz, the guided light L3 will be deflected even more than the position indicated by ``■'' in FIG. 7(2). However, at this position, when the frequency is 2 GHz, the guided light L2 that is diffracted once is emitted, although it is small, so as in this example, the range from ■ to ■° in FIG. 7(2) is It is preferable to use it as a deflection range.

Next, changes in the configuration that can be made in the optical deflection device 50 described above will be explained. The following explanation will be given using the first and third inclined finger chirp IDT17.27 sides as an example, but it goes without saying that similar changes can be made to the second and fourth side.
This can also be done on the slanted finger chirp IDT18.28 side. First, in the above embodiment, the surface acoustic wave 1
5.25 frequency is changed continuously from 2GHz to IGHz, but on the other hand, from IGHz to 2GHz.
It may be changed up to GHz. In this case, only the direction of deflection of the light beam tom is reversed. Furthermore, if the frequency is changed from 2 to 1 to 2 to IGHz, the L-th light beam will be deflected back and forth, making it possible to scan the light beam back and forth.

Furthermore, in the embodiment described above, the guided light L! for the surface acoustic wave 15 with a frequency of 2 GHz! (that is, the angle between the electrode finger that excites 2 GHz of the first inclined finger chirp IDT 17 and the traveling direction of the guided light L1) is 6°, and the electrode finger that excites IGHz of the first inclined finger chirp IDT 17 is 6°. The angle between the waveguide light and the traveling direction is 3°, while the electrode fingers that excite 2 GHz and IGHz of the third inclined finger chirp IDT 27 have an angle of 18° with the traveling direction, respectively.
9°, but generally the minimum and maximum frequencies of surface acoustic waves 15.25 are fl, fz (fz −2fl)
In the above example, 6°, 3°, 18°
, 90 and the angles set as θ, θ/2.3θ, and 3, respectively.
If θ/2 is used, the above-mentioned Bragg condition can always be satisfied in any case. This will be obvious by referring to FIGS. 7(1) and (2).

Note that the shape of the inclined finger chirp IDT17.27 is
Even when the shape is defined by the surface acoustic wave 1
5.25 minimum and maximum frequency r1, fz fz-2f'
, it is not necessarily necessary to set it so that
For example, the maximum frequency f2 may be set to be slightly smaller than the value 2f1.

However, the slanted finger chirp IDT17.
27, this IDT shape is utilized to the maximum extent, and the maximum deflection angle range is obtained without the second-order diffracted light generated at the minimum frequency r1 entering the deflection angle range from fl to f'! It is preferable to change the surface acoustic wave frequency between -"2fl.

Furthermore, in the present invention, the minimum and maximum frequencies 'l and fz of the surface acoustic waves 15.25 are set to f2fi2f, and the frequencies of the surface acoustic waves 15.25 are changed so that they are equal to each other. It is not always necessary to do this, and even if the frequency and traveling direction of the surface acoustic waves 15.25 are changed individually, the first and third tilted finger chirp I
Depending on the shape and arrangement of DT17.27, it is possible to satisfy the above-mentioned relationship of tic1+[K1-2+IIK2-111+3.

However, as in the above embodiment, surface acoustic waves 15.
By changing the frequency of 25 in the same way, it becomes possible to drive two tilted finger chirp IDTs with a common driver.
This is convenient because only one expensive driver is required.

Furthermore, in the device of the present invention, instead of the inclined finger chirp IDT17.18.27.28 described above, a so-called curved finger chirp IDT in which the electrode finger interval changes stepwise and each electrode finger has an arc shape is used. You can also do that. FIG. 8 shows an example of the arrangement of this curved finger chirp IDT. In this example, the first curved finger chirp IDT 117 also
In the third curved finger chirp 1DT127, the rightmost electrode finger portion in the figure generates a surface acoustic wave 15.25 with a maximum frequency r2, and the leftmost electrode finger portion generates a surface acoustic wave 15.25 with a minimum frequency r5.
．． 25 (indicated by a broken line in the figure). In this case as well, if fz-2f, the guided light L1 for the first surface acoustic wave 15 with the maximum frequency f2
The first curved finger chirp IDT11
The electrode finger portion at the left end of 7 forms an angle of θ/2 with respect to the traveling direction of the guided light Ll, and the -direction third curved finger chirp I
The right and left end electrode finger parts of DT127 are the guided light L1.
Both IDs make angles of 3θ and 3θ/2 with respect to the traveling direction of
All you need to do is create and place TIL7.127. Also, the second
, the fourth curved finger chirp IDT118.128 may be formed in the same manner as the above-mentioned IDTl17.127.

Furthermore, in order to make the light beam enter the optical waveguide 12 and emit it to the outside, the above-mentioned LGC 13,
In addition to 14, a coupler prism or the like may be used, or a light beam may be made to enter and exit directly from the end face of the optical waveguide 12. Moreover, in order to convert the light beams L and L' into parallel beams when they are divergent beams, or to focus the light beams emitted from the optical waveguide 12, a waveguide lens or a normal external lens can be used.

Further, when the optical waveguide 12 is made of ZnO instead of the Ti-diffused LiNbO3 described above, for example, the maximum and minimum frequencies of the surface acoustic waves 15.25 may be set to 1. O.G.
Hz, 0.5 GHz, a deflection angle range of about Δδ-8° is obtained.

Further, in the present invention, three or more guided lights are guided in an optical waveguide, each of these guided lights is diffracted and deflected by a surface acoustic wave, and the three or more light beams output from the optical waveguide are diffracted. It may be configured to scan a predetermined surface without overlapping each other. In this device as well, the means for respectively diffracting and deflecting the two adjacent guided light beams is configured as described above, so such an optical deflection device is also included in the device of the present invention. .

Further, in the second optical deflection device of the present invention, three or more surface acoustic waves are propagated in the optical waveguide in order to deflect one guided light, and these surface acoustic waves cause one guided light to be deflected into three It may be diffracted or deflected more than once. In this device as well, the above-described effects can be obtained by using two adjacent surface acoustic waves, so such a device is also included in the second optical deflection device of the present invention.

(Effects and Effects of the Invention) As explained above in detail, the optical deflection device of the present invention is configured so that two light beams deflected by surface acoustic waves scan the surface to be scanned separately. Furthermore, in addition to the above, the second optical deflection device of the present invention is configured such that a light beam once deflected by a surface acoustic wave is further deflected by another surface acoustic wave. Compared to recording or reading two images by dividing the deflection angle range of the book's light beam into two,
The deflection angle range per image can be essentially doubled in the first optical deflection device and quadrupled in the second optical deflection device. Therefore, according to the device of the present invention, it is possible to record or read large-sized images,
Also as above.

Since an extremely wide range of deflection angles can be obtained, the distance from the optical deflection device to the surface to be scanned can be shortened, thereby achieving miniaturization of optical scanning recording devices and reading devices.

In the device of the present invention, a wide deflection angle range can be obtained as described above without setting the frequency of each surface acoustic wave extremely high, so when using an IDT as a surface acoustic wave generating means, There is no need to set the line width extremely small, and this IDT can be easily manufactured using currently established technology. Further, as described above, there is no need to set the frequency of the alternating voltage applied to the IDT to be extremely high, and therefore the driver of the IDT can be easily and inexpensively formed.

Furthermore, in the device of the present invention, the two light beams scanned in parallel on a predetermined surface are guided and deflected within a common optical waveguide, so the scanning position of the two light beams can be adjusted. However, it can be done easily and with high precision.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing an embodiment of the first optical deflection device of the present invention, and FIGS. 2.3 and 4 are explanatory diagrams showing examples of deflection directions of two light beams in the device of the present invention. , FIG. 5 is a schematic plan view showing an embodiment of the second optical deflection device of the present invention, FIG. 6 is a plan view showing an enlarged part of the optical deflection device of FIG. 5, and FIG. FIG. 8 is an explanatory diagram illustrating the mechanism of light beam deflection in the second optical deflection device of the present invention, and is a plan view showing another example of the surface acoustic wave generating means used in the present invention. 10, 50... optical deflection device 11... groups
Plate 12... Optical waveguide 13... LGC for light beam incidence 14... LGC for light beam output Engineering 5... First surface acoustic wave 1B... Second surface acoustic wave 17... 1st inclined finger chirp IDT18...
・Second inclined finger chirp IDT19.19゛...High frequency amplifier 20.20°...Sweeper 21,21゛...Light
source. 25...Third surface acoustic wave 26...Fourth surface acoustic wave 27...Third inclined finger chirp IDT28...
・T2O from the fourth inclined finger chirp...Scanned surface 117...First curved finger chirp IDT118...
Second curved finger chirp IDT127...Third curved finger chirp IDT128...Fourth curved finger chirp ID
TL1... Guided light L before entering the first surface acoustic wave
2... Guided light L3 that has passed through the first surface acoustic wave...
The guided light that has passed through the third surface acoustic wave is 1°...the guided light that has passed through the second surface acoustic wave is 2°...the guided light that has passed through the second surface acoustic wave is 3' ... Guided light L S % L s ' that has passed through the fourth surface acoustic wave... 1 at the scanning start end of the light beam... Wave number vector 1 of guided light Ll, 2... Wave number of guided light L2 3... Wave number vector of the guided light L3 [K,... Wave number vector of the first surface acoustic wave [K2.
... Wave number vector of the third surface acoustic wave Fig. 2 Fig. 3 S0 Fig. 4'; Q 6 [R1 Fig. 7 Fig. 8 [21

Claims (8)

[Claims] (1) An optical waveguide formed of a material through which surface acoustic waves can propagate; a first surface acoustic wave generating means for generating a surface acoustic wave in the optical waveguide; and diffracting and deflecting the second guided light traveling in a direction intersecting the optical path of the second guided light traveling in the optical waveguide. a second surface acoustic wave generating means for generating a second surface acoustic wave in the optical waveguide, and these first and second surface acoustic wave generating means An optical deflection device characterized in that two guided light beams are arranged so as to scan a predetermined surface without overlapping each other. (2) The first and second surface acoustic wave generating means each include a pair of inclined-finger chirped interdigitated electrodes in which the electrode finger spacing changes stepwise and the direction of each electrode finger changes stepwise; 2. The optical deflection device according to claim 1, further comprising a driver that applies an alternating voltage whose frequency changes continuously to the electrode pair. (3) The first and second surface acoustic wave generating means each include a curved-finger chirped interdigitated electrode pair in which the electrode finger spacing changes stepwise and each electrode finger has an arc shape; 2. The optical deflection device according to claim 1, further comprising a driver that applies an alternating voltage whose frequency changes continuously. (4) an optical waveguide formed from a material through which surface acoustic waves can propagate; a first surface acoustic wave generating means for generating a surface acoustic wave in the optical waveguide; and diffracting and deflecting the second guided light traveling in a direction intersecting the optical path of the second guided light traveling in the optical waveguide. a second surface acoustic wave generating means for generating a second surface acoustic wave in the optical waveguide; and a second surface acoustic wave generating means for generating a second surface acoustic wave in the optical waveguide; The first guided light,
third surface acoustic wave generating means for generating in the optical waveguide a third surface acoustic wave that is diffracted and deflected in a direction that further amplifies the deflection due to the diffraction; The second waveguide light travels in a direction intersecting the optical path of the second waveguide light,
a fourth surface acoustic wave generating means for generating in the optical waveguide a fourth surface acoustic wave that is diffracted and deflected in a direction that further amplifies the deflection due to the diffraction, and the first and third surface acoustic waves The generating means is the first
The wave number vectors of the first guided light before and after being diffracted by the surface acoustic wave are |k_1, |k_2, respectively, and the wave number vector of the first guided light diffracted by the third surface acoustic wave is |k_3, respectively. When the wave number vectors of the first and third surface acoustic waves are |K_1 and |K_2, |k_1+|K_
1=|k_2 |k_2+|K_2=|k_3 The second and fourth surfaces are formed so as to continuously change the frequency and traveling direction of the first and third surface acoustic waves, respectively, while satisfying the following conditions. The elastic wave generating means includes the second elastic wave generating means.
The wave number vectors of the second guided light before and after being diffracted by the surface acoustic wave are |k_4, |k_5, respectively, and the wave number vector of the second guided light diffracted by the fourth surface acoustic wave is |k_6, respectively. When the wave number vectors of the second and fourth surface acoustic waves are |K_3 and |K_4, |k_4+|K_
3=|k_5 |k_5+|K_4=|k_6 The first, second, third, and The surface acoustic wave generating means of No. 4 is
An optical deflection device characterized in that the first and second guided lights emitted from the optical waveguide are arranged so as to scan a predetermined surface without overlapping each other. (5) Each of the first, second, third, and fourth surface acoustic wave generating means is a pair of inclined-finger chirped interdigitated electrodes in which the electrode finger spacing changes stepwise and the direction of each electrode finger changes stepwise. and a driver for applying an alternating voltage whose frequency changes continuously to the electrode pair. (6) The first, second, third, and fourth surface acoustic wave generating means each include a pair of curved-finger chirped interdigitated electrodes in which the electrode finger spacing changes stepwise and each electrode finger has an arc shape; 5. The optical deflection device according to claim 4, further comprising a driver that applies an alternating voltage whose frequency changes continuously to the electrode pair. (7) mth and (m+2)th surface acoustic wave generating means [m=
1 and/or 2] are both frequencies f_1 to f_2
(f_2≒2f_1), the surface acoustic wave is configured to generate a surface acoustic wave whose frequency changes while taking the same value, and the incident angle of the m-th guided light L_1 that is incident on the m-th surface acoustic wave of frequency f_2. is θ, the electrode fingers of the portion of the chirped interdigitated electrode pair constituting the m-th surface acoustic wave generating means that generates the surface acoustic wave of frequency f_1 are θ with respect to the traveling direction of the guided light L_1. /2 of the chirped interdigitated electrode pair constituting the (m+2)th surface acoustic wave generating means, the electrode fingers of the portions that generate surface acoustic waves of frequencies f_2 and f_1 respectively correspond to the guided light L.
7. The optical deflection device according to claim 5 or 6, wherein the optical deflection device is formed to form an angle of 3θ or 3θ/2 with respect to the traveling direction of _1. (8) Each of the chirped interdigitated electrode pairs constituting the m-th and (m+2)-th surface acoustic wave generating means is driven by a common driver. Light deflection device.