JP2001091976A - Light deflection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To two-dimensionally deflect a light beam with low driving voltage and a high utilization factor of the light by utilizing a small-sized optical waveguide element which uses only one substrate and does not necessitate optical axis control. SOLUTION: The device is provided with a thin film optical waveguide 3 arranged on a conductive single crystal substrate 1 and having an epitaxial electro optical effect. An electrode 5 for controlling the light beam in the optical waveguide is arranged on the optical waveguide 3. A light emitting prism 9 for emitting the light beam in the optical waveguide 3 is arranged on the more downstream light beam side of the optical waveguide 3 than the position where the electrode 5 for controlling the light beam in the optical waveguide is arranged. A buffer layer is arranged between the single crystal substrate 1 and the optical waveguide 3. An upper side electrode 5 is arranged between the optical waveguide 3 and the electrode 5 for controlling the light beam in the optical waveguide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical deflecting element, and more particularly, to an optical deflecting element capable of two-dimensionally deflecting a light beam incident on an optical waveguide. This light deflection element includes a laser printer, a digital copier, a facsimile, a display, an optical interconnection, a barcode reader, a glyph code reader, a pickup for an optical disk, a surface inspection optical scanner, a surface shape estimation optical scanner, and the like. It can be used throughout optoelectronics.

[0002]

2. Description of the Related Art As a laser beam light deflector used in laser beam printers, digital copiers, facsimile machines, etc., a rotating polygon mirror called a polygon mirror for deflecting a beam from a gas laser or a semiconductor laser, and its rotation. Laser reflected by polygon mirror
A lens composed of an fθ lens that condenses a beam in a state of linear movement at a constant velocity on an image forming surface such as a photoconductor is typically used. The light deflecting device using such a polygon mirror is not only large in size, but also has a problem in that the polygon mirror is mechanically rotated at a high speed by a motor, so that there is a problem in durability and noise is generated. In addition, the galvanomirror and cantilever mirror have a problem of deflection accuracy.

On the other hand, as a solid-state electric laser beam light deflector, there is a light deflector utilizing an acousto-optic effect. Among them, an optical waveguide type deflector which is smaller than a bulk type acousto-optical device is known. Is expected. This optical waveguide device is being studied for application to a printer or the like as a laser beam light scanning device that solves the drawbacks of a laser beam light scanning device using a polygon mirror. Optical deflection element of the optical waveguide type deflection, an optical waveguide including, for example, LiNbO ₃ and ZnO, have a means for entering the laser beam into the optical waveguide, further a light beam in the optical waveguide by acousto-optic effect It has a comb-shaped electrode for exciting surface acoustic waves and means for outputting the deflected light beam from the optical waveguide. Is added to
However, the light deflection element using the acousto-optic effect generally has a diffraction efficiency of several tens of percent, so that the light utilization efficiency is reduced or the zero-order light must be processed. Power supplies are expensive and large, such as laser printers, digital copiers, facsimiles, displays, optical interconnections,
Application to bar code readers, glyph code readers, optical disk pickups, and the like has been difficult.

On the other hand, A. Yariv, Optical Electronics, 4th ed., Which uses an oxide ferroelectric material having an electro-optical effect having a higher modulation speed than the acousto-optical effect.
(New York, Rinehart and Winston, 1991) pp. 336-3
There is known a prism type light deflecting element described in 39. As such an element, there is a bulk element using a ceramic or a single crystal. However, since the size is large and the driving voltage is considerably high, a practical deflection angle cannot be obtained. Also, a prism-type domain-inverted light deflector or a prism-type electrode light deflector using a cascade-type prism using a LiNbO ₃ single-crystal wafer on which a Ti diffusion type optical waveguide or a proton exchange type optical waveguide is manufactured is described in Q. Chen. , et al., J. Lightwave Tech. vol. 12 (1
994) 1401. and Japanese Patent Application Laid-Open No. 1-248141. However, since the electrode spacing of about 0.5 mm, which is the thickness of the LiNbO ₃ single crystal wafer, is required, the driving voltage is still high,
In the above document, a deflection angle of only about 0.2 degrees is obtained even with a driving voltage of ± 600 V, and there is a problem that a practical deflection angle cannot be obtained. Also, JP-A 2-3118
27 shows a method of changing the effective refractive index of the optical waveguide by an electro-optic effect to change the exit angle from the prism coupler. However, since the disclosed configuration is not an electrode arrangement that changes the refractive index of the optical waveguide portion provided with the prism coupler, it is not possible to actually change the emission angle, and temporarily change the emission angle. Even if this is achieved, the electrode spacing is increased because the electrodes are provided on the surface of the optical waveguide, and a practical deflection angle cannot be obtained as in the case of the above-mentioned document.

On the other hand, the present inventor has proposed an oxide optical waveguide provided on a conductive substrate and having an epitaxial or unidirectional electro-optic effect, and a light source for inputting a light beam into the optical waveguide. Invented is a prism type optical deflection element using a thin film optical waveguide having electrodes for deflecting a light beam in the optical waveguide by an electro-optic effect.
(Japanese Unexamined Patent Publication No. 9-5797) solved the problem of the drive voltage described above. However, the electromagnetic field distribution of the laser light propagating through the optical waveguide leaks into the substrate. In many cases, the absorption coefficient of a substrate having a practical resistivity is large, and the exudation component is strongly absorbed by free carriers in the conductive substrate, and the propagation loss in the thin-film optical waveguide is reduced by the scattering of the optical waveguide itself. In addition, the absorption becomes several tens of dB / cm due to absorption, and there is a problem that light utilization efficiency may be insufficient in practice.

Generally, in a device having a coplanar electrode arrangement, a metal electrode on an optical waveguide and a silicon
A method has been adopted in which a cladding layer of O ₂ is inserted to prevent seepage of an electromagnetic field into a metal electrode and to avoid absorption of propagating light. However, when SiO ₂ is provided between the conductive substrate and the oxide optical waveguide, there is a problem that an oxide optical waveguide having an electro-optical effect of epitaxial or single orientation cannot be produced because SiO ₂ is amorphous. there were. Furthermore, the relative permittivity of the oxide optical waveguide material having an electro-optic effect ranges from several tens to several thousands, which is extremely large as compared with the relative permittivity of SiO ₂ of 3.9, and the above-described thin film optical waveguide structure on a conductive substrate. In the above, since a series capacitor is formed as an equivalent circuit, the effective voltage applied to the thin-film optical waveguide is only a few% or less with respect to the applied voltage, and there is a problem that a large increase in the driving voltage is eventually caused. .
Further, in an i-GaAs waveguide which is a compound semiconductor, i-Ga
An i-AlGaAs cladding layer is inserted between the As waveguide and the n-AlGaAs lower cladding layer to prevent the electromagnetic field from seeping into the n-AlGaAs lower cladding layer, thereby freeing the n-AlGaAs lower cladding layer. A method of avoiding absorption by carriers has been adopted. However, it is a material completely different from a compound semiconductor, epitaxial growth is not easy, and the relative dielectric constant has no known method of providing a similar structure in an oxide optical waveguide having an electro-optic effect ranging from tens to thousands. Was. For this reason, the present inventors provided a high dielectric constant epitaxial or unidirectional buffer layer on a conductive substrate, and formed an oxide thin film optical waveguide having an epitaxial or unidirectional electro-optical effect thereon. And a structure in which an electrode is further provided thereon is invented by FN97-00386.
(Submitted on July 22, 1997), it is possible to achieve both low drive voltage characteristics and low light propagation loss characteristics.

However, any of the above-described light deflection systems only performs one-dimensional deflection of light.
Since it is necessary to combine two deflecting means, there has been a problem that at least optical axis adjustment is required and the device configuration is complicated. For example, in order to perform two-dimensional deflection using the method shown in JP-A-9-5797, a polygon mirror, a galvano mirror, a cantilever mirror, a bulk type acousto-optical element,
Alternatively, a combination with a bulk-type electro-optical element can be considered, but each conventional problem eventually occurs. Therefore, it is essential to perform two-dimensional deflection by one optical waveguide element.

Such a two-dimensional deflecting element is disclosed in Japanese Patent Application Laid-Open No. 62-238537 by the acousto-optic effect of two surface acoustic waves for changing the deflection angle in the substrate plane and the output angle at the output unit. Although a two-dimensionally deflectable optical waveguide element is shown as a combination of the means, the diffraction efficiency of the acousto-optic deflection is several tens of percent, so that the light utilization efficiency is reduced or multi-order light must be processed. The problem, such as the expensive and large driving circuit for controlling the frequency of several hundred MHz, has not been solved yet. In addition, Japanese Patent Application Laid-Open
-130327 shows a two-dimensional deflecting element that deflects in the plane of the substrate by the acousto-optic effect of surface acoustic waves and changes the emission angle by the electro-optic effect by applying a voltage to the output grating. . But,
The conventional problems of acousto-optic deflection remain. In addition, since the electrode for controlling the refractive index of the grating section is provided on the surface of the optical waveguide, the electrode interval becomes large, and even when 100 V is applied, the change of the emission angle is 0.04 mrad (0.002 mrad).
Degree) and there is a problem that it is not possible to obtain a practical deflection angle as in the examples of the above-mentioned literature and patents. Further, since diffraction is eventually used also in the grating part, the light use efficiency is reduced and the zero-order light and There was also a problem that multiple-order light had to be processed.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has a small size, low driving voltage, and high light utilization without the need for optical axis adjustment by an optical waveguide element using one substrate. It is an object of the present invention to propose an optical waveguide device capable of efficiently deflecting a light beam two-dimensionally.

[0010]

According to the first aspect of the present invention, there is provided a conductive or semiconductive single-crystal substrate serving as a lower electrode or a conductive or semiconductive substrate serving as a lower electrode on a surface thereof. An optical waveguide having an electro-optical effect of epitaxial or mono-orientation provided on a substrate on which an epitaxial or uni-oriented thin film is formed, and disposed on the optical waveguide, the single-crystal substrate or epitaxial or A region for changing a refractive index according to an applied voltage and deflecting a light beam propagating through the optical waveguide in a first direction according to an applied voltage is formed between the thin film and a single orientation thin film. An electrode for controlling a light beam in the optical waveguide to be formed;
An emission prism that emits a light beam in the optical waveguide in a second direction that intersects the first direction, and changes the temperature of the optical waveguide, and, according to the temperature, from the emission prism. Temperature control means for controlling the emitted light beam to deflect the emitted light beam in the second direction.

Here, the single orientation refers to a case where the intensity of a specific crystal plane parallel to the substrate surface in the X-ray diffraction pattern of the thin film is 1% or less with respect to the intensity of other crystal planes.
Epitaxial refers to a case where a thin film having a single orientation has a single orientation in the in-plane direction of the substrate.

When a voltage is applied between the light beam controlling electrode in the optical waveguide and the single crystal substrate or the epitaxial or unidirectional thin film, a region where the refractive index changes according to the applied voltage is formed. Is done. As described above, since the refractive index of the region changes according to the applied voltage, the light beam propagating through the optical waveguide can be deflected in the first direction according to the applied voltage.

The temperature control means for controlling the output light beam changes the temperature of the optical waveguide, and deflects the light beam emitted from the output prism in the second direction according to the temperature.

Thus, the present invention can perform two-dimensional deflection of a light beam as described above.

According to the present invention, as described above, two-dimensional deflection can be performed on a single single-crystal substrate or a substrate on which a single-crystal thin film is formed by providing an exit prism and a temperature control means. The optical beam can be two-dimensionally deflected with high light use efficiency while eliminating the need for optical axis adjustment.

Further, since the optical waveguide is arranged on the substrate, the length to which the voltage is applied can be shortened, so that the light beam can be two-dimensionally deflected to a small size and a low driving voltage.

Here, the temperature control means for controlling the output light beam includes a resistor or a bottom surface of the output prism disposed on the optical waveguide near the output prism via a cladding layer having a smaller refractive index than the optical waveguide. It may be a resistor disposed on a nearby side surface. This makes it possible to control the temperature only in the vicinity of the bottom surface of the exit prism, which is the minimum area where the temperature needs to be controlled, and to shorten the reaction time for the deflection in the second direction.

In order to form a region in which the refractive index changes in accordance with the applied voltage, the light beam controlling electrode in the optical waveguide has a triangular pattern having two sides that are not parallel to each other. May be applied to generate regions having different refractive indices corresponding to the triangular pattern, wherein the optical waveguide has a triangular polarization domain inversion region having two sides that are not parallel to each other, and By applying a voltage to the in-waveguide light beam control electrode, different refractive indices may be generated in the triangular polarization domain inversion region and other regions.

Here, the substrate satisfies the three conditions of having a refractive index smaller than that of the optical waveguide, being conductive, and matching the crystal lattice with the optical waveguide. desirable.

For this reason, the surface of the single crystal substrate may be provided with an epitaxial or unidirectional conductive or semiconductive oxide having a lower refractive index than the optical waveguide. If the single-crystal substrate or the epitaxial or single-oriented thin film is a transparent oxide having a refractive index smaller than that of the optical waveguide, light utilization efficiency is improved, and it is more preferable.

The optical waveguide may be provided on a single-crystal substrate or a single-crystal thin film via a buffer layer having a refractive index smaller than that of the epitaxial or mono-oriented optical waveguide. Therefore, light loss can be reduced, and high light use efficiency can be achieved.
The effective voltage in the optical waveguide can be increased.

Further, a cladding layer having a smaller refractive index than the optical waveguide may be provided on the surface of the optical waveguide. This prevents not only the dust from directly adhering to the optical waveguide and lowering the light utilization efficiency, but also reduces the light loss due to light scattering on the surface of the optical waveguide and improves the light utilization efficiency. it can.

The optical waveguide may be an oxide ferroelectric.

Next, each element of the present invention will be described in more detail.

In the present invention, a conductive or semiconductive single-crystal substrate as a lower electrode substrate, or a conductive or semiconductive epitaxial or single-oriented single-crystal thin film provided between the substrate and the optical waveguide. Materials that can be used are SrTiO ₃ doped with Nb, Al-doped ZnO, I
_{n 2 O 3, RuO 2,} BaPbO 3, SrRuO 3, YBa 2 Cu 3 O 7-x, SrVO 3, La
NiO ₃ , La _0.5 Sr _0.5 CoO ₃ , ZnGa ₂ O ₄ , CdGa ₂ O ₄ , CdGa ₂ O ₄ , M
oxides such as g ₂ TiO ₄ and MgTi ₂ O ₄ , simple semiconductors such as Si, Ge, and diamond, AlAs, AlSb, AlP, GaAs, GaSb, In
P, InAs, InSb, AlGaP, AlLnP, AlGaAs, AlInAs, AlAsS
III-V based compound semiconductors such as b, GaInAs, GaInSb, GaAsSb, InAsSb, ZnS, ZnSe, ZnTe, CaSe, Cdte, HgSe, HgT
e, CdS and other II-VI based compound semiconductors, Pd, Pt, Al, A
Although metals such as u and Ag can be used, it is often advantageous to use an oxide for the film quality of the oxide thin film optical waveguide disposed on the top. These conductive or semi-conductive single-crystal substrates, or conductive or semi-conductive epitaxial or single-oriented single-crystal thin film, the crystal structure of the ferroelectric thin film, and deflection speed, switching speed, or It is desirable to select according to the carrier mobility required by the modulation rate. Also,
The resistivity is 10 ⁸ Ωcm or less, preferably 10 ⁶ Ωcm
The following is effective in terms of the RC time constant, but if the resistivity is such that the voltage drop is negligible, it can be used as the lower electrode. When using a silicon substrate having a higher refractive index than a normal optical waveguide material, for example, a high refractive index of 3.45, the thickness of the buffer layer is considerably increased to prevent light leakage to the substrate. Need arises,
It is desirable for the buffer layer to have a lower refractive index than that of the optical waveguide material in order to reduce the thickness of the buffer layer and drive at a low voltage.

Materials that can be used as a substrate for a conductive or semiconductive epitaxial or unidirectional thin film provided between the substrate and the optical waveguide include SrTiO ₃ , BaTiO ₃ ,
_{BaZrO 3, LaAlO 3, ZrO 2} , Y 2 O 3 8% -ZrO 2, MgO, MgAl 2 O 4, L
Oxides such as iNbO ₃ , LiTaO ₃ , Al ₂ O ₃ , and ZnO, simple semiconductors such as Si, Ge, and diamond, AlAs, AlSb, AlP, GaAs,
GaSb, InP, InAs, InSb, AlGaP, AlLnP, AlGaAs, AlIn
III such as As, AlAsSb, GaInAs, GaInSb, GaAsSb, InAsSb
-V compound semiconductor, ZnS, ZnSe, ZnTe, CaSe, Cdte, H
II-VI compound semiconductors such as gSe, HgTe, and CdS can be used, but the use of an oxide is often advantageous for the film quality of the oxide thin film optical waveguide disposed at the top.

When a buffer layer is used, the buffer layer has a refractive index smaller than that of the thin-film optical waveguide material, and the ratio between the relative dielectric constant of the buffer layer and the relative dielectric constant of the optical waveguide is 0.002 or more, preferably the ratio of the buffer layer. The ratio of the relative permittivity of the optical waveguide to the permittivity is 0.006 or more, and the relative permittivity of the buffer layer is 8
The above materials are selected. Further, the buffer layer material needs to be able to maintain the epitaxy relationship between the conductive substrate material and the optical waveguide material. The condition for maintaining this epitaxy relationship is that the buffer layer material is similar to the crystal structure of the conductive substrate material and the optical waveguide material, and the difference in lattice constant is 10%.
The following is desirable, but it is sufficient if the epitaxy relationship can be maintained without necessarily following this relationship. Specifically, in an ABO ₃ type perovskite type oxide, for example, SrTiO ₃ , BaTiO ₃ , (S
_{r 1-x Ba x) TiO} 3 (0 <x <100), PbTiO 3, Pb 1-x La x (Zr y T
i _1-y ) _{1-x / 4} O ₃ (0 <x <30, 0 <y <100, P depending on the values of x and y
ZT, PLT, PLZT), Pb (Mg _1/3 Nb _2/3 ) O ₃ , KNbO ₃ etc., as a hexagonal system, for example, ferroelectrics represented by LiNbO ₃ , LiTaO ₃ etc., tungsten bronze type oxide Sr _x Ba _1-x Nb ₂ O
₆ , Pb _x Ba _1-x Nb ₂ O _6, etc., and also Bi ₄ Ti ₃ O ₁₂ , P
b ₂ KNb ₅ O _15, selected from _{K 3 Li 2 Nb 5 O 1} 5, ZnO further more substituted derivatives. It is effective that the ratio of the thickness of the buffer layer to the thickness of the optical waveguide is 0.1 or more, preferably 0.5 or more, and the thickness of the buffer layer is 10 nm or more.

As the material of the thin film optical waveguide, an oxide is selected.
And specifically ABO_ThreeSquare perovskite type
BaTiO3 as a crystal, orthorhombic or pseudocubic_Three, PbTi
O_Three, Pb _1-xLa_x(Zr_yTi_1-y)_{1-x / 4}O_Three (depending on the values of x and y
PZT, PLT, PLZT), Pb (Mg_1/3Nb_{Two / 3}) O_Three, KNbO_ThreeEtc.
For example, LiNbO as a crystal system_Three, LiTaO_ThreeForcing
Sr for conductor and tungsten bronze type_xBa_1-xNb_TwoO₆, Pb_x
Ba_1-xNb_TwoO₆In addition to this, Bi_FourTi_ThreeO₁₂, Pb_TwoKNb_Five
O_Fifteen, K_ThreeLi_TwoNb_FiveO_Fifteen, Selected from the above substituted derivatives, etc.
Devour. Thickness of thin-film optical waveguide is typically 0.1 μm to 10 μm
It is set during the
Can be

When a cladding layer is used, a buffer layer
Similar ones can be used. That is, the thin-film light guide
It has a smaller refractive index than the waveguide material and the cladding layer
The relative permittivity and the relative permittivity of the optical waveguide is 0.002 or more,
Preferably, the relative dielectric constant of the cladding layer and the relative dielectric constant of the optical waveguide are derived.
The electrical conductivity ratio is 0.006 or more, and the relative dielectric constant of the cladding layer
Materials with a rate of 8 or more are selected. Clad layer material
In addition, it is possible to maintain the epitaxy relationship with the optical waveguide.
Is not always necessary and may be a polycrystalline thin film.
If it is necessary to obtain a good interface,
It is necessary to be able to maintain taxi relations. This epita
The condition that can maintain the xy relationship is that the cladding layer material is
Similar to the crystal structure of the thin film optical waveguide material, the difference between the lattice constants
It is desirable to be 10% or less, but this relationship is not necessarily
It suffices if the epitaxy relationship can be maintained without obeying it. Concrete
ABO_ThreeSquare perovskite oxide
SrTiO as a crystal, orthorhombic or pseudo-cubic_Three, BaTi
O_Three, (Sr_1-xBa_x) TiO_Three (0 <x <100), PbTiO_Three, Pb_1-xLa_x(Zr
_yTi_1-y)_{1-x / 4}O_Three (0 <x <30, 0 <y <100, depending on x and y values
PZT, PLT, PLZT), Pb (Mg_1/3Nb_2/3) O_Three, KNbO_ThreeEtc., six
LiNbO for example as a tetragonal system_Three, LiTaO_ThreeStrong represented by
Sr for dielectric, tungsten bronze oxide _xBa_1-xNb
_TwoO₆, Pb_xBa_1-xNb_TwoO₆In addition to this, Bi_FourTi
_ThreeO₁₂, Pb_TwoKNb_FiveO_Fifteen, K _ThreeLi_TwoNb_FiveO_Fifteen, ZnO and more substitution
Selected from derivatives. The thickness of the cladding layer and the optical waveguide
The film thickness ratio is 0.1 or more, preferably 0.5 or more, and
It is effective that the thickness of the cladding layer is 10 nm or more.
You.

The electrodes for controlling the light beam in the optical waveguide are Al, T
Various metals or alloys such as i, Cr, Ni, Cu, Pd, Ag, In, Sn, Ta, W, Ir, Pt, and Au, and transparent materials such as ITO and Al-doped ZnO that have a smaller refractive index than the optical waveguide Oxide electrodes can be used. When a cladding layer having a smaller refractive index than that of the optical waveguide is provided between the optical waveguide and the upper electrode, any material can be used for the upper electrode, but the drive voltage is increased. It is desirable to use a transparent oxide electrode such as Al or Zn-doped ZnO. The electrode for controlling a light beam in the optical waveguide has a prism-shaped pattern having two sides that are not parallel to each other. By applying a voltage, regions having different refractive indices corresponding to the electrode pattern can be generated. When the optical waveguide has a prism-shaped polarization domain inversion region having two sides that are not parallel to each other, a prism-shaped polarization domain inversion region is applied by applying a voltage to a light beam control electrode in the optical waveguide. Different refractive indices can be generated in the regions.

As the exit prism, a prism having a higher refractive index than the optical waveguide can be used according to the optical waveguide material and the wavelength of light.
It can be selected from O ₂ ), GaP, GaAs or refractive index glass. The angle of the bottom angle of the prism or the angle of the inclined surface with respect to the bottom surface can be appropriately set according to the refractive index of the optical waveguide, a change in the refractive index of the optical waveguide due to the electro-optic effect, and the refractive index of the prism.

The thin-film optical waveguide can be provided with a thin-film lens for the purpose of controlling the incident light beam. Make the effective refractive index of the lens part larger than that of the thin film optical waveguide part,
It is possible to provide a mode index type circular or pupil type convex lens, a Fresnel type or a grating type lens, for example, after manufacturing a lens-shaped ferroelectric thin film having a refractive index larger than that of a thin film optical waveguide. , By forming a thin-film optical waveguide thereover.

The clad layer, the thin film optical waveguide, the buffer layer, and the lens layer are formed by electron beam evaporation, flash evaporation, ion plating, Rf-magnetron sputtering, ion beam sputtering, laser ablation, MBE, CVD. It is produced by a vapor phase growth method selected from plasma CVD, MOCVD and the like, and a solid phase growth method of a thin film produced by a wet process such as a sol-gel method and a MOD method. A solution of a metal organic compound such as a metal alkoxide or an organic metal salt is applied to a substrate by a wet process such as a sol-gel method or a MOD method,
It is most effective to further bake the buffer layer, the thin film optical waveguide, and the cladding layer by solid phase epitaxial growth by baking. These solid-phase epitaxial growth methods have lower equipment costs and better uniformity on the substrate surface than various vapor-phase growth methods, and are important for controlling the structure of the buffer layer, the thin-film optical waveguide, and the cladding layer. Control of the refractive index can be easily realized with good reproducibility simply by blending the composition of the metal organic compound precursor according to the composition of the thin film having the necessary refractive index for the buffer layer, the thin film optical waveguide, and the cladding layer. Buffer layer with low light propagation loss,
Growth of thin-film optical waveguides and cladding layers is possible.

As the temperature control means for controlling the emitted light beam, a method of controlling the temperature from the substrate side of the optical waveguide element using a metal resistor, a ceramic heater, a Peltier element or the like provided with a feedback circuit using a thermocouple or the like is also available. There is
Since the response speed is greatly affected by heat conduction and heat capacity,
It is preferable to carry out from the optical waveguide side. As a method of controlling the temperature from the optical waveguide side, a heating resistor is provided near the exit prism on the thin film optical waveguide material or the cladding layer material, or a heating resistor is provided on the side surface near the lower surface of the exit prism. Temperature control.
Such thin film resistors include Cu-Mn alloy, Cu-Ni alloy,
Ni-Cr-Al alloy, Fe-Cr alloy, Ni-Cr alloy, metal materials such as platinum, molybdenum, tungsten, Ir-O, Ru-O, Ru-Ti-
O, Ta-Si-O, Ti-Si-O, Ba-Ru-O, Cr-Si-O, Ti-C-Si-O,
Oxides such as Nb-Si-O and ITO, Ta-Si-C, Ta-Si, Ta-N, and polysilicon can be used. However, when the heating resistor is not transparent in the wavelength region of the guided light, if the heating resistor is directly formed without the interposition of the cladding layer, the propagation loss deteriorates due to light absorption of the heating resistor. It is preferable to form a heating resistor. Such cladding layers include SiO ₂ , SiC, SiON, SiN, La-SiO
Overglaze materials for thermal heads, such as N, BP-Si, and TaO, can be used because they have excellent resistance to thermal history. The heating resistor and the clad layer can be formed by patterning with a metal mask or a photoresist using sputtering, electron beam evaporation, CVD, PCVT, or MOD. In particular, if the MOD method is used, the cladding layer and the heating resistor can be formed at low cost by repeating the application step and the baking step by screen printing.

[0035]

Embodiments of the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 1, an optical deflecting element according to this embodiment is a thin film having an epitaxial or unidirectional electro-optic effect provided on a conductive or semiconductive single crystal substrate 1. An optical waveguide 3 is provided. An electrode 5 for controlling a light beam in the optical waveguide is provided on the optical waveguide 3. Further, as shown in FIG. 4, an emission prism for emitting the light beam in the optical waveguide 3 is located downstream of the position on the optical waveguide 3 where the electrode 5 for controlling the light beam in the optical waveguide is disposed. 9 are arranged.

The buffer layer 2 is disposed between the single crystal substrate 1 and the optical waveguide 3, and the upper electrode 5 is disposed between the optical waveguide 3 and the light beam controlling electrode 5 in the optical waveguide. Have been.

When light is introduced into the optical waveguide 3 provided on the single crystal substrate 1, a part of the total light intensity seeps into the substrate,
When the transparency of the substrate is low, the component that seeps into the substrate is absorbed, resulting in a propagation loss accompanying light propagation. However, in the present embodiment, in consideration of the case where a transparent conductive substrate cannot be used, as shown in FIG. , Thereby reducing the propagation loss. In order for the buffer layer 2 to function as an isolation layer between the thin-film optical waveguide 3 and the conductive substrate 1, it is necessary that the refractive index of the buffer layer material is smaller than the refractive index of the thin-film optical waveguide material. In addition, in order to reduce the light propagation loss due to scattering due to the optical waveguide surface and grain boundaries in the optical waveguide to a practical level, the buffer layer material must be able to maintain the epitaxy relationship between the conductive substrate material and the optical waveguide material. Is essential. Also, the optical waveguide material desirably has a high electro-optic coefficient, and the conductive substrate material desirably has a low resistivity.

The thickness ratio between the buffer layer 2 and the optical waveguide 3 needs to be at least 0.1 or more in order to reduce the propagation loss to 1 dB / cm or less. Further, when assuming operation in the single mode TE ₀ is appropriate to 0.5 or more.

Next, when the upper metal electrode 5 is provided on the thin-film optical waveguide 3 and the frequency of light in the thin-film optical waveguide exceeds the plasma frequency of the metal electrode, the metal electrode 5 The exuded component is strongly absorbed by the carrier in the metal, resulting in propagation loss. However, in the present embodiment, as shown in FIG. 1, the region in which this seeping occurs is replaced by the cladding layer 4 having low absorption, thereby eliminating absorption by the upper metal electrode 5 and reducing propagation loss. In order for the cladding layer 4 to function as an isolation layer between the thin-film optical waveguide 3 and the metal electrode 5, it is generally necessary that the refractive index of the cladding layer material is smaller than the refractive index of the thin-film optical waveguide material. If a transparent conductive thin film can be used as the upper electrode 5, no propagation loss occurs even without using such a cladding layer 4.

On the other hand, when the buffer layer 2 exists between the conductive substrate 1 and the thin-film optical waveguide 3, the voltage applied between the upper and lower electrodes is distributed according to the respective capacities of the thin-film optical waveguide and the buffer layer. The effective voltage that can be applied decreases. However, in the present embodiment, a high effective voltage can be applied to the thin-film optical waveguide by using the buffer layer 2 having a constant thickness and a high dielectric constant.
For example, the total applied voltage is V ₀ and the relative permittivity of the thin-film optical waveguide is ε.
_w, the film thickness d _w, the epsilon _b dielectric constant of the buffer layer, the thickness and d _b, the effective voltage V _w applied to the thin-film optical waveguide 3 is expressed as follows.

V _w = C _b / (C _w + C _b ) × V ₀ = ε _b d _w / (ε _w d _b + ε _b d _w ) × V ₀ [1] The relative permittivity of the buffer layer 2 is Since the relative permittivity of the optical waveguide 3 is close to 4000, it is desirable that ε _b / ε _{w has a value} of 0.002 or more, that is, an effective voltage of 8 or more that can secure 2% or more of the applied voltage. The above principle is exactly the same for the cladding layer 4.

As described above, the oxide thin film optical waveguide 3 having the electro-optical effect of the epitaxial or single orientation is provided on the transparent or conductive single-crystal substrate 1 serving as the lower electrode. Further, a transparent upper electrode 5 is provided thereon, or a high dielectric constant epitaxial or unidirectional buffer layer 2 is provided on a conductive or semiconductive single crystal substrate 1 serving as a lower electrode. An oxide thin-film optical waveguide 3 having a refractive index higher than that of the buffer layer 2 and having an epitaxial or unidirectional electro-optic effect is provided thereon, and a refractive index smaller than that of the optical waveguide 3 is provided thereon, if necessary. By providing a cladding layer 4 having a high dielectric constant and an upper electrode 5 thereon, a structure in which the optical waveguide 3 is sandwiched between upper and lower electrodes even with an oxide ferroelectric material is possible. And, it is possible to lower the driving voltage without impairing the low optical propagation loss characteristic.

Here, in FIG. 1, the upper electrode 5 has a prism shape (triangular shape), and the buffer layer 2, the thin film optical waveguide 3,
When a voltage V is applied between the lower electrode and the substrate 1 located at a distance d via the cladding layer 4 as needed, the thin-film optical waveguide 3 has a primary electro-optical effect.
In the case where an effect is obtained, a change in the refractive index according to the following equation occurs in a region sandwiched between the upper electrode 5 and the substrate 1 and in other regions. Note that r is a constant when the thin-film optical waveguide 3 has the Pockels effect.

Δn = 1/2 · r · n ³ · (V / d) [2] When the thin-film optical waveguide 3 has the Kerr effect, which is a secondary electro-optic effect, the refractive index change according to the following equation Occurs. R is a constant when the thin-film optical waveguide 3 has the Kerr effect.

Δn = 1/2 · R · n ³ · (V / d) ² [3] In these cases, as shown in FIG.
Assuming that the length of the light beam in the traveling direction is L and the width (base) is W, the light beam 8 after passing through this electrode portion is deflected by the deflection angle θ according to the following equation.

Θ = Δn × L / W [4] When the prism type electrode is provided as the upper electrode 5, the light beam 6 can be deflected. In the deflected state, there is no undeflected component and the scattered light is extremely small. Since the number is small, the problems of insertion loss and crosstalk can be solved. Note that, instead of providing a prism-shaped electrode as the upper electrode 5, a thin-film optical waveguide is used.
In the case where 3 has a prism-shaped polarization domain inversion region having two sides that are not parallel to each other, a voltage is applied to the upper electrode 5 for controlling a light beam in the optical waveguide to thereby form a prism-shaped polarization domain inversion region and other regions. In this region, a different refractive index can be generated, and the deflection of the laser beam can be obtained similarly.

On the other hand, as shown in FIG. 3, the base angle α and the refractive index n
_When the emission prism 9 of _p is provided on the surface of the thin-film optical waveguide 3 having the effective refractive index N, the light is emitted at an angle γ ₀ according to the following equation, where the initial element temperature is T ₀ .

Γ ₀ = cos ⁻¹ [n _p (T ₀ ) × sin [sin ⁻¹ (N (T ₀ ) / n _p (T ₀ )) − α]] − α [5] the temperature control means such as a heater, varying the temperature of the thin-film optical waveguide 3 to T _1, the thin-film optical waveguide 3
The effective refractive index of the light beam and the refractive index of the emission prism change with a change in temperature, and the emission angle of the light beam 8 changes according to the following equation.

Γ ₁ = cos ⁻¹ [n _p (T ₁ ) × sin [sin ⁻¹ (N (T ₁ ) / n _p (T ₁ )) − α]] − α [6] That is, the prism electrode In the direction perpendicular to the deflection direction according to the following equation.

Θ = γ ₀ -γ ₁ [7] As described above, in the present embodiment, two-dimensional deflection of the light beam is possible. As described above, in the present embodiment, the optical waveguide element using a single substrate enables the light beam to be two-dimensionally deflected with low driving voltage and high light use efficiency without the need for optical axis adjustment. Laser printers, digital copiers, facsimiles, displays, optical interconnections, bar code readers, glyph code readers, optical disk pickups, surface inspection optical scanners, surface shape estimation optical scanners It can be used for all opto-electronics including those.

[0052]

[Embodiment 1] In this embodiment, as shown in FIG. 4, an opaque but low-resistance Nb-doped SrTiO ₃ (10
0) A 400 nm-thick epitaxial PZT (95/5) buffer layer is grown on the single crystal lower electrode substrate 1,
nm epitaxial PLZT (9/65/35) thin film optical waveguide 3 is grown, and a prism type for controlling the light beam in the optical waveguide
By forming the ITO electrode 5, providing the incident end face and the exit prism 9, and providing the heater 10 on the lower surface of the substrate,
A two-dimensional deflection element was manufactured.

The buffer layer and the optical waveguide 3 were manufactured by solid phase epitaxial growth. 0.6 M PZT (95 /
5) The precursor solution is spin-coated on a 10 mm square Nb-doped SrTiO ₃ substrate, heated in an O ₂ atmosphere at 10 ° C./sec and maintained at 350 ° C., and then heated to 100 ° C./sec. 750 ℃
And finally the electric furnace was turned off to cool. As a result, a first-layer PZT thin film having a thickness of 100 nm was grown by solid phase epitaxial growth. By repeating this three more times, an epitaxial PZT buffer layer having a total thickness of 400 nm was obtained. Next, a 0.6 M concentration of a precursor solution for PLZT (9/65/35) was spin-coated on a Nb-doped SrTiO ₃ substrate having a buffer layer, and the same as the buffer layer at 10 ° C./s in an O ₂ atmosphere.
After the temperature was raised at ec and maintained at 350 ° C., the temperature was raised at 100 ° C./sec and maintained at 750 ° C. Finally, the electric furnace was turned off and cooled. As a result, a first-layer PLZT thin film having a thickness of 100 nm was grown by solid phase epitaxial growth. By repeating this process nine more times, an epitaxial PLZT thin film optical waveguide with a total film thickness of 1000 nm was obtained. Crystallographic relationship is PLZT (100) with single orientation
// PZT (100) // Nb-SrTiO ₃ (100), in-plane orientation PLZT [001] /
/ PZT [001] // Nb-SrTiO ₃ [001] structure was obtained. PLZT
On the thin film optical waveguide, a 200 nm thick film is formed by sputtering.
A prism-shaped electrode 5 for controlling a light beam in an optical waveguide having a base of 100 μm and a height of 1000 μm made of an ITO thin film was formed by a lift-off method. Furthermore, a light beam incident portion is formed by polishing the end face, and a rutile prism 9 having a base angle of 60 degrees and a base of 5 mm is fixed to the upper part of the thin-film optical waveguide, and further a 20 mm × 70 mm × A two-dimensional deflection element was manufactured by fixing the substrate on a 0.35 mm silicon heater 10.

First, in order to evaluate the characteristics of the optical waveguide,
By a prism coupling to introduce a laser beam of 633 nm in PLZT thin film optical waveguide of the present embodiment, showing characteristics entering the 5 dB / cm with a practical level it was determined for light propagation loss of the TE ₀ mode. The relative dielectric constants of the PZT buffer layer and the PLZT thin-film optical waveguide of the present example were measured.
And 900, and the effective voltage of the PLZT thin-film optical waveguide obtained from the above equation [1] is 53%.

The wavelength 6 collimated to a width of 100 μm from the incident end face to the PLZT thin-film optical waveguide 3 of the two-dimensional deflecting element of this embodiment.
A 33 nm laser beam 6 was introduced. The applied laser beam is applied with a voltage between the prism-shaped electrode 5 for controlling the light beam in the optical waveguide and the lower Nb-doped SrTiO ₃ substrate electrode 1 so that different refractive indices are present in the lower part of the electrode and other parts. Occurred and the laser beam was deflected.
FIG. 5 shows the relationship between the deflection angle and the voltage obtained by determining the deflection angle from the displacement of the laser spot position on the projection plane. Since the voltage distribution to the thin-film optical waveguide shows voltage dependence due to the difference in the dielectric properties of the buffer layer and the thin-film optical waveguide 3, the deflection characteristics are also low.
At 5 V or less, voltage dependence was exhibited, but at 5 V or more, a first-order electro-optic effect according to equation [4] was exhibited, and the deflection angle at 20 V was 5
At 0 mrad (2.9 degrees), the effective electro-optic coefficient was about 60 pm / V. The response speed was about 10 MHz. Further, by heating with the silicon heater 10, the optical waveguide
3 and the refractive index of the rutile prism 9 changed, and the light beam 8 emitted from the emission prism 9 was deflected in a direction orthogonal to the deflection direction by applying a voltage to the prism electrode due to the change in the refractive index. FIG. 6 shows the relationship between the temperature and the deflection angle. The deflection angle varied almost linearly with temperature, and was deflected by 24 mrad (1.3 degrees) when the temperature was increased from 25 ° C. to 90 ° C., and a response speed of about 4 Hz was obtained. The light beam 7 thus emitted was two-dimensionally deflected like the light beam 8 according to the voltage and the temperature. [Embodiment 2] In this embodiment, an opaque but low-resistance Nb-doped SrTiO ₃ (100) single-crystal lower electrode substrate was formed on a 400 nm-thick epitaxial PZT (85/85 1
5) grow a buffer layer, then grow a 1000 nm thick epitaxial PZT (52/48) thin film optical waveguide, and further form a prismatic ITO electrode for controlling the light beam in the optical waveguide,
A two-dimensional deflection element as shown in FIG. 4 was manufactured by providing an incident end face and an exit prism and providing a heater on the lower surface of the substrate.

The buffer layer and the optical waveguide were produced by solid phase epitaxial growth in the same manner as in Example 1. First, a precursor solution for PZT (85/15) was filled with 10 mm square Nb-doped SrTi
Spin coating is performed on the O ₃ substrate, and the O ₂
By firing in an atmosphere, a 100 nm-thick first-layer PZT thin film was grown by solid phase epitaxial growth. By repeating this three more times, an epitaxial PZT buffer layer having a total thickness of 400 nm was obtained. Next, the precursor solution for PZT (52/48) is spin-coated on an Nb-doped SrTiO ₃ substrate having a buffer layer, and baked in an O ₂ atmosphere using an electric furnace, so that a 100 nm-thick The first PZT thin film was grown by solid phase epitaxial growth. By repeating this process nine more times, an epitaxial PZT thin film optical waveguide with a total film thickness of 1000 nm was obtained. The crystallographic relationship is that of unidirectional PZT (10
0) // PZT (100) // Nb-SrTiO ₃ (100), in-plane orientation PZT [001]
// PZT [001] // A structure of Nb-SrTiO ₃ [001] was obtained. P
200 nm film thickness by sputtering on ZT thin film optical waveguide
A prism-shaped electrode 5 for controlling a light beam in an optical waveguide having a base of 100 μm and a height of 1000 μm made of an ITO thin film was formed by a lift-off method. Furthermore, a light beam incident portion is formed by polishing the end face, and a rutile prism 9 having a base angle of 60 degrees and a base of 5 mm is fixed to the upper part of the thin-film optical waveguide, and further a 20 mm × 70 mm × A two-dimensional deflection element was manufactured by fixing the substrate on a 0.35 mm silicon heater 10.

First, in order to evaluate the optical waveguide characteristics,
Was determined the introduced light propagation loss of the TE ₀ mode laser beam of 633 nm in PZT thin film optical waveguide of the present embodiment by a prism coupling, optical propagation loss indicates the characteristic entering the practical level with 4 dB / cm Was. Also, when the relative permittivity of the PZT buffer layer and the PLZT thin film optical waveguide of the present example was measured,
PLZ is 400 and 600 respectively, which is obtained from the above equation [1]
The effective voltage of the T thin film optical waveguide was 63%.

The wavelength 633 collimated into the PZT thin-film optical waveguide 3 of the two-dimensional deflection element of this embodiment to a width of 100 μm from the incident end face.
A laser beam 6 of nm was introduced. The incident laser beam is a prism-shaped electrode for controlling the light beam in the optical waveguide
By applying a voltage between 5 and the lower Nb-doped SrTiO ₃ substrate electrode 1, different refractive indices were generated in the lower part and the other part of the electrode, and the laser beam was deflected. The relationship between the voltage and the deflection angle obtained from the displacement of the laser spot position on the projection surface shows the primary electro-optic effect according to equation [4] as shown in Fig. 7, and the deflection angle at 20V Is 6
At 0 mrad (3.4 degrees), the effective electro-optic coefficient was about 50 pm / V. A response speed of about 10 MHz was obtained, and a deflection of 300 mrad (17.2 degrees) was obtained when 100 V was applied.

Further, by heating with the silicon heater 10, the refractive indexes of the optical waveguide 3 and the rutile prism 9 are changed, and the light beam 7 emitted from the emitting prism 9 is changed by the voltage change to the prism electrode. It was deflected in the direction perpendicular to the direction of deflection by application. In the present embodiment, since the exit prism having a base angle of 60 degrees is used, characteristics of temperature and deflection angle as shown in FIG.
The deflection was 20 mrad (1.1 degrees) when the temperature was raised from 90 to 90 ° C, and the response speed was about 4 Hz. Light beam 7 emitted in this manner
Was deflected two-dimensionally like a light beam 8 according to voltage and temperature. [Comparative Example 1] In this comparative example, an insulating and 500 μm thick
An epitaxial PZT (52/48) thin film optical waveguide with a thickness of 1000 nm is grown on a SrTiO ₃ (100) single crystal substrate, and a prismatic ITO electrode for controlling the light beam in the optical waveguide is formed. A two-dimensional deflection element as shown in FIG. 4 was produced by providing a light emitting prism and a heater on the lower surface of the substrate.

The optical waveguide is a solid phase epitaxy in the same manner as in the first embodiment.
Manufactured by axial growth, crystallographic relationship
PZT (100) // SrTiO_Three(100), in-plane orientation PZT [001] // S
rTiO _ThreeThe structure of [001] was obtained. On the PZT thin film optical waveguide
Bottom 1 of 200 nm ITO thin film by sputtering
A prism for controlling the light beam in an optical waveguide of 00 μm and height of 1000 μm
The electrode 5 was formed by a lift-off method. SrTiO_ThreeBase
An In electrode was deposited on the back surface of the plate. In addition, polishing the end face
Forming a light beam entrance,
In the upper part of the wave path, rutile with a base angle of 60 degrees and a base of 5 mm
Fix the prism 9 and add a 20 mm × 70 mm × 0.35 mm
By fixing the substrate on the conheater 10, two-dimensional
A deflection element was manufactured.

SrTiO of this comparative example_ThreeThe relative permittivity of the substrate is 250, P
The relative permittivity of the ZT thin film optical waveguide was 600. SrTiO_Three(100)
The thickness of the single crystal substrate is 500 μm, and that of the PZT (52/48) thin film optical waveguide
Since the film thickness is 1000 nm, the PZT thin film obtained from the above equation [1] is used.
The effective voltage of the film optical waveguide was only 0.1%. Comparative example
Of the two-dimensional deflection element of PZT thin-film optical waveguide 3 from the incident end face
Laser beam of 633 nm wavelength collimated to a width of 100 μm
System 6 was introduced. The incident laser beam is an optical waveguide
Prism type electrode 5 and SrTiO for internal light beam control _ThreeSubstrate back
A voltage was applied between the In electrode 1 and the 0 V at 20 V.
Only a 1 mrad deflection could be observed. On the other hand,
Heating by the heater 10 makes the optical waveguide 3
The refractive index of the prism 9 changes.
The light emitted from the exit prism 9 is pre-
In the direction perpendicular to the direction of deflection by applying a voltage to the
Deflected, 18mrad (1.0 degree) deflection at 25 ° C to 90 ° C
did. Thus, in this comparative example, the deflection angle due to the voltage application
Is not practical because it is small.
Use a cylindrical lens, etc., because of a large difference from the direction angle.
Good two-dimensional deflection cannot be performed even with a magnifying optical system
No. Embodiment 3 Another embodiment of the present invention is SrTiO._Three(100)
SrRuO with a thickness of 200 nm to serve as a lower electrode on a crystalline substrate_ThreeConductivity
Epitaxial growth of 1600 nm thick by growing a thin film epitaxially
Grow a Char PZT (85/15) buffer layer, then 1000
 nm epitaxial PZT (52/48) thin film optical waveguides grown
And a prismatic ITO for controlling the light beam in the optical waveguide
The electrode 5 is formed by a lift-off method,
Provide a projection prism and a heater on the lower surface of the substrate
Thus, a two-dimensional deflection element as shown in FIG. 4 was manufactured.

The SrRuO ₃ conductive thin film can be epitaxially grown by sputtering. The buffer layer and the optical waveguide can be manufactured by solid phase epitaxial growth in the same manner as in the first embodiment. The crystallographic relationship is unidirectional
PZT (100) // PZT (100) // SrRuO ₃ (100) // SrTiO ₃ (10
0) is obtained. On the PZT thin film optical waveguide, a 200 μm thick ITO thin film with 200 nm
A prism electrode 5 for controlling a light beam in an optical waveguide having a height of 2000 μm is formed by a lift-off method. Furthermore, the light beam incidence part is formed by polishing the end face,
A rutile prism 9 with a base angle of 60 degrees and a base of 5 mm is fixed above the thin-film optical waveguide.
A two-dimensional deflection element was manufactured by fixing the substrate on the substrate.

In the two-dimensional deflection element of this embodiment, the PZT
The collimated laser beam 6 incident from the end surface of the thin film optical waveguide is deflected by applying a voltage between the prism type electrode 5 for controlling the light beam in the optical waveguide and the lower SrRuO ₃ conductive thin film. Further, by heating with the silicon heater 10, the refractive index of the optical waveguide 3 and the rutile prism 9 changes, and the light emitted from the emission prism 9 is applied to the prism electrode as in the second embodiment due to the change in the refractive index. The light is deflected in a direction perpendicular to the direction of the voltage application.
The deflection angle is 50 mrad (2.9
Degree), the response speed was about 10 MHz. Further, the temperature is raised from 25 ° C. to 90 ° C. by heating with the silicon heater 10 to 24
Deflected by mrad (1.3 degrees), the response speed was about 4 Hz. A two-dimensional deflection element can be configured as described above. Embodiment 4 In this embodiment, as shown in FIG.
Opaque but low-resistance Nb-doped S as in Example 1.
A 400 nm-thick epitaxial PZT (95/5) buffer layer is grown on the lower electrode substrate 1 of rTiO ₃ (100) single crystal, and then a lens-shaped epitaxial PZT (30/70) to be a mode index lens A thin film is formed, and then an epitaxial PLZT (9/65/35) thin film optical waveguide 3 having a thickness of 1000 nm is grown, and a prismatic ITO for controlling a light beam in the optical waveguide is further formed.
The two-dimensional deflection element was manufactured by forming the electrode 5, providing the semiconductor laser diode 14, the incident end face, and the emitting prism 9, and providing a heater on the lower surface of the substrate.

The buffer layer, the lens layer, and the thin film optical waveguide were manufactured by solid phase epitaxial growth in the same manner as in Example 1. First, similarly to Example 1, Nb-doped SrTiO ₃
The substrate was spin-coated with a precursor solution for PZT (95/5) and baked in an electric furnace four times to obtain an epitaxial PZT buffer layer with a total thickness of 400 nm. Next, a PZT (30/70) precursor solution was spin-coated on the Nb-doped SrTiO ₃ substrate on which the buffer layer was formed, and baking at 350 ° C. was repeated eight times to obtain an amorphous PZT (30/70) thin film. . Next, using a negative electron beam resist, electron beam exposure was performed to form a pupil-shaped lens having an aperture diameter of 400 μm to form a resist pattern. next
By etching the amorphous PZT (30/70) thin film with aqueous HCl, the pupil-shaped amorphous PZT (30
/ 70) After forming a thin film and stripping the resist, solid phase epitaxial growth was performed, and an 800 nm-thick epitaxial PZT (30
/ 70) The lens layer 11 was formed. Finally, as in the example, PL
By repeating the spin coating of the precursor solution for ZT (9/65/35) and firing in an electric furnace 10 times, an epitaxial PLZT thin film optical waveguide with a total film thickness of 1000 nm was obtained on the buffer layer having the lens layer 11. . The crystallographic relationship is a single orientation PLZT (100) thin film optical waveguide // PZT (100) lens layer // PZT (100) buffer layer // Nb-SrTiO ₃ (100) substrate, in-plane orientation PLZT [001] Thin film optical waveguide // PZT [001] lens layer // PZT [001] buffer layer
// The structure of Nb-SrTiO ₃ [001] substrate was obtained. On the PLZT thin-film optical waveguide, a prism-shaped electrode 5 for controlling the light beam in the optical waveguide having a base of 200 μm and a height of 2000 μm was formed by an ITO thin film having a thickness of 200 nm by sputtering by a lift-off method. Further, a glass paste for spin-on-glass is applied and baked on the optical waveguide layer by a screen printing method to form an interlayer insulating layer 12 having a thickness of 1 μm, and then ruthenium octylate and tetra-n-butyl titanate are formed thereon. By applying and baking a paste for forming a resistor consisting of the same by screen printing, a width of 0.1 mm, a length of 2 mm,
A 0.1 μm-thick Ru—Ti-based resistor film 13 was formed by the MOD method. Furthermore, after forming the light beam incident part by polishing the end face, the semiconductor laser 14 is installed, and a rutile prism 9 with a base angle of 60 degrees and a base of 2 mm is fixed on the upper part, and two-dimensional deflection is performed. An element was manufactured.

In the two-dimensional deflection element of this embodiment, the PLZ
Semiconductor laser provided on the end face for incidence on T thin-film optical waveguide 3.
The laser beam incident from 12 has a width of 200
Collimated to μm. Its collimated laser
The beam is a prism type for controlling the light beam in the optical waveguide.
Electrode 5 and lower Nb-doped SrTiO_ThreeApply a voltage between the substrate electrode 1
Is deflected by the addition. Furthermore, the exit prism
Immediately before, via the cladding layer 12, the PLZT thin-film optical waveguide 3
A heating resistor for controlling the emitted light beam provided in the
By applying a voltage to 13),
The emission angle from the projection prism 9 changes. Prism type
The deflection angle when applying 20 V to the electrode 5 was 50 mrad (2.9 degrees).
The response speed was about 10 MHz. Also, 20 to the resistor 13
V, 18mrad (1.0 degree) deviation by applying 2msec pulse voltage
Response speed by setting the duty ratio to 30%
About 160Hz was obtained. As described above, the thin-film lens 11
Two-dimensional deflection with semiconductor laser mounted
A device can be manufactured, and at the same time, a resistor is formed on the thin film waveguide.
2D deflection element with improved response speed
Can be made. Embodiment 5 FIG. 10 shows another embodiment of the present invention.
As described above, the Nb doping amount was reduced compared to Example
Nb-doped SrTiO with electrical conductivity_Three(100) Single crystal lower electrode
1000nm thick epitaxial PZT (52/48) thin on the substrate
Growing a film optical waveguide and controlling the light beam in the optical waveguide
Prism-type Al-doped ZnO electrode for
The prism bottom is formed by sputtering.
Nb-SiO on the side near the surface _TwoThe emission plate on which the resistor film 13 is formed
By creating a rhythm, a two-dimensional deflection element
Was.

The PZT (52/48) thin film optical waveguide can be epitaxially grown by Rf magnetron sputtering.
Crystallographic relationship is unidirectional PZT (100) thin film optical waveguide // Nb
The structure of the -SrTiO ₃ (100) substrate is obtained. 200 nm thick Al-doped ZnO by sputtering on PZT thin film optical waveguide
A prism-shaped electrode 5 for controlling a light beam in an optical waveguide having a base of 100 μm and a height of 2000 μm made of a thin film can be formed by a lift-off method. Further, a light beam incident portion is formed by fixing a rutile prism 9 having a base angle of 60 degrees and a base of 2 mm, and a resistor for controlling an emitted light beam (corresponding to the resistor of claim 3). The angle of the base angle forming 13) is 60 degrees,
2 mm by fixing a rutile prism 9 with a base of 2 mm
A dimensional deflection element can be manufactured.

In the two-dimensional deflection element of this embodiment, the PZT
The collimated laser beam incident from the rutile prism 15 for incidence on the thin-film optical waveguide 3 includes a prism-type electrode 5 for controlling a light beam in the optical waveguide and a lower Nb-doped SrTiO _3.
It is deflected by applying a voltage between itself and the substrate electrode 1. Further, by applying a voltage to the output light beam controlling resistor 13 and heating it, the optical waveguide 3 and the rutile prism 9 are heated.
The output light from the output prism 9 is deflected by this change in the refractive index in a direction orthogonal to the direction of deflection by applying a voltage to the prism electrode, as in the second embodiment. The deflection angle is 40 mrad (2.3 degrees) with 20 V applied to the prism electrode,
The response speed was about 100 kHz. Also, 20 to the resistor
A response speed of about 120 Hz was obtained by deflecting 13 mrad (0.7 degrees) by applying a pulse voltage of 2 msec and applying a duty ratio of 25%. As described above, by arranging the resistor above the thin film waveguide, a two-dimensional deflection element with improved response speed can be manufactured. COMPARATIVE EXAMPLE 2 In this comparative example, a 400 nm-thick epitaxial PZT (85 mm) was deposited on a lower electrode substrate of opaque but low-resistance Nb-doped SrTiO ₃ (100) single crystal as in Example 1.
/ 15) Grow a buffer layer, then grow a 1000 nm-thick epitaxial PZT (52/48) thin-film optical waveguide, and furthermore, prismatic ITO electrode for controlling light beam in the optical waveguide, end face for incidence, and emission A two-dimensional deflecting element was fabricated by forming an ITO electrode for controlling the light beam on the upper part of the grating.

The buffer layer and the optical waveguide are the same as in the first embodiment.
In this manner, it was produced by solid phase epitaxial growth. Conclusion
Crystallographic relationship is unidirectional PZT (100) // PZT (100) // Nb-S
rTiO _Three(100), in-plane orientation PZT [001] // PZT [001] // Nb-SrT
iO_ThreeThe structure of [001] was obtained. Out on the PZT thin film optical waveguide
A grating with a firing period of 2 μm was provided. PZT thin film light
200 nm thick ITO thin film by sputtering on the waveguide
Optical beam in optical waveguide with 100 μm bottom and 1000 μm height by film
A prism-shaped electrode for controlling the
Lift-off electrode with 1000μm square output light beam control
It was formed by the fu method. In addition, polishing the end face
Therefore, a light beam incident part is formed, and
The top of the control electrode has a base angle of 60 degrees and a base of 5 mm.
The chill prism was fixed, and a two-dimensional deflection element was fabricated.

The wavelength 633 collimated into the PZT thin film optical waveguide of the two-dimensional deflecting element of this embodiment to a width of 100 μm from the incident end face.
nm laser beam was introduced. Laser incident
The laser beam was deflected by applying a voltage between a prism electrode for controlling the light beam in the optical waveguide and a lower Nb-doped SrTiO ₃ substrate electrode. Further, by applying a voltage between the output light beam control electrode provided on the output grating and the lower Nb-doped SrTiO ₃ substrate electrode, the refractive index of the output grating portion changes, and this refractive index is changed. The change caused the output angle to change. However, the emitted laser is split into a plurality of beams, so that the intensity of the primary beam is weak and the change in the emission angle is also two.
The value was about 6 mrad at 0 V, which was smaller than that in Example 2. [Embodiment 6] As another embodiment of the present invention, a 200 nm thick Al-doped ZnO film serving as a lower electrode is formed on an Al ₂ O ₃ (0001) single crystal substrate.
A conductive thin film is epitaxially grown, and then a 600 nm-thick epitaxial LiNbO ₃ thin film optical waveguide 3 is grown, and further, a prism type Al-doped ZnO for controlling a light beam in the optical waveguide.
An electrode 5 is formed, an input grating 16 and an output prism 9 are provided, a Peltier element 17 is further provided on the lower surface of the substrate, and a fiber array 18 is provided on the output side to constitute an optical switch as shown in FIG. be able to.

The Al-doped ZnO thin film is grown epitaxially by Rf magnetron sputtering, and then in-situ
With u, a LiNbO ₃ thin film optical waveguide can be epitaxially grown by Rf magnetron sputtering. The crystallographic relationship is unidirectional LiNbO ₃ (0001) thin film optical waveguide // Al-ZnO (00
1) Conductive thin film // The structure of Al ₂ O ₃ (0001) substrate is obtained. L
After a prism-shaped domain inversion region (corresponding to the polarization domain inversion region of claim 5) having a base of 100 μm and a height of 1000 μm is formed on the iNbO ₃ thin-film optical waveguide, a 200 nm-thick Al-doped region is formed thereon by sputtering. A rectangular electrode 5 for controlling a light beam in an optical waveguide having a base of 100 μm and a height of 1000 μm made of a ZnO thin film is formed by etching. Also, TiO ₂
A grating 16 for light beam incidence is formed by patterning, a rutile prism 9 with a base angle of 45 degrees and a base of 3 mm is fixed on the upper part of the LiNbO ₃ thin-film optical waveguide, and further on the lower surface of the substrate. Peltier element 17 for temperature control
The optical switch of 1 × 8 as shown in FIG. 11 was constructed by arranging two systems of 250 μm pitch 4-core fiber arrays 18 on the emission side.

In the two-dimensional deflection element of this embodiment, LiN
The collimated laser beam 20 incident on the bO ₃ thin-film optical waveguide 3 from the incident grating 16 is placed between the prism-type electrode 5 for controlling the light beam in the optical waveguide and the lower conductive Al-doped ZnO thin-film electrode 1. The voltage is applied to deflect the light on the first four-core fiber array. Further, by changing the temperature by the Peltier element 17, the output angle of the light beam 8 from the output prism 9 changes, and the prism type electrode 5 for controlling the light beam in the optical waveguide and the lower conductive Al-doped ZnO thin film electrode 1 are used. By applying a voltage between
Deflect on fiber array 2 1x with the function of switching to two systems with two different temperatures as described above
Eight optical switches can be configured. Comparative Example 3 In this comparative example, Al ₂ O
₃ Place a 200 nm thick layer of A on the (0001)
Epitaxially growing a l-doped ZnO conductive thin film, then growing an epitaxial LiNbO ₃ thin film optical waveguide with a thickness of 600 nm, further forming a prism type Al-doped ZnO electrode for controlling the light beam in the optical waveguide, grating for incidence and emission A grating is provided, and an Al-doped ZnO electrode for controlling a light beam is formed above the grating for emission.
An optical switch was configured by disposing a fiber array on the emission side.

The Al-doped ZnO thin film is epitaxially grown by Rf magnetron sputtering, and then in-situ
With u, a LiNbO ₃ thin film optical waveguide can be epitaxially grown by Rf magnetron sputtering. The crystallographic relationship is unidirectional LiNbO ₃ (0001) thin film optical waveguide // Al-ZnO (00
1) Conductive thin film // The structure of Al ₂ O ₃ (0001) substrate is obtained. L
After forming a prism-shaped domain-inverted region with a base of 100 μm and a height of 1000 μm on the iNbO ₃ thin-film optical waveguide, an optical waveguide with a base of 100 μm and a height of 1000 μm made of a 200-nm-thick Al-doped ZnO thin film is formed on the upper part by sputtering. An inner light beam control rectangular electrode is formed by etching. Also, a grating for the light beam incident by patterning TiO ₂ and an exit grating formed, further Al-doped ZnO electrode through the optical waveguide in the light beam for output light beam control 2000μm angle to the upper portion of the grating for emitting It is formed by etching in the same manner as the control electrode, and a 250 μm pitch 4-core fiber array is
A 1 × 8 optical switch was constructed by system arrangement.

In the two-dimensional deflection element of this comparative example, LiN
The collimated laser beam incident from the grating for incidence on the bO ₃ thin film optical waveguide is composed of a prism type electrode for controlling the light beam in the optical waveguide and a lower conductive Al-doped ZnO.
By applying a voltage between the thin-film electrode and the thin-film electrode, the light is deflected on the first four-core fiber array. Furthermore, by applying a voltage between the output light beam control electrode and the lower conductive Al-doped ZnO thin film electrode, the output angle from the output grating changes, and the prism type for controlling the light beam in the optical waveguide. A voltage is applied between the electrode 5 and the lower conductive Al-doped ZnO thin film electrode to deflect on the second fiber array. However, since the emitted laser is split into a plurality of beams, crosstalk is large.
Stable operation was not obtained as compared with.

[0074]

As described above, according to the present invention, since a single substrate is provided with an exiting prism and a temperature control means to perform two-dimensional deflection, it is not necessary to adjust the optical axis and to use high light. The light beam can be efficiently deflected two-dimensionally, and since the optical waveguide is arranged on the substrate, the length to which a voltage is applied can be shortened. Can be two-dimensionally deflected.

[Brief description of the drawings]

FIG. 1 is a diagram showing a principle diagram of an electromagnetic field distribution in an optical waveguide.

FIG. 2 is a diagram illustrating a principle of light beam deflection by a prism electrode.

FIG. 3 is a diagram illustrating a principle of deflection of a light beam from an exit prism due to a temperature change.

FIG. 4 is a diagram illustrating a two-dimensional deflection element according to the first embodiment.

FIG. 5 is a diagram illustrating a deflection characteristic of a light beam by a prism electrode of the two-dimensional deflection element according to the first embodiment.

FIG. 6 is a diagram illustrating a deflection characteristic of a light beam from an exit prism due to a temperature change of the two-dimensional deflection element according to the first embodiment.

FIG. 7 is a diagram illustrating a deflection characteristic of a light beam by a prism electrode of a two-dimensional deflection element according to a second embodiment.

FIG. 8 is a diagram illustrating a deflection characteristic of a light beam from an exit prism due to a temperature change of a two-dimensional deflection element according to a second embodiment.

FIG. 9 is a diagram illustrating a two-dimensional deflection element according to a fourth embodiment.

FIG. 10 is a diagram illustrating a two-dimensional deflection element according to a fifth embodiment.

FIG. 11 is a diagram illustrating a two-dimensional deflection element according to a sixth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductive substrate 3 Optical waveguide 5 Electrode 9 Emission prism 10 Heater

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shigenori Nakamura 430 Sakai, Nakagawa-cho, Ashigarashimo-gun, Kanagawa Green Tech Nakai F-term in Fuji Xerox Co., Ltd. 2K002 AA01 AA05 AA06 AB08 BA06 BA13 CA02 CA22 DA05 EA30 EB04 EB05 HA02 HA11

Claims (10)

[Claims] 1. A conductive or semiconductive single-crystal substrate serving as a lower electrode, or a substrate having a conductive or semiconductive epitaxial or unidirectional thin film serving as a lower electrode formed on a surface thereof. An optical waveguide having an electro-optical effect of epitaxial or mono-oriented orientation, and a voltage applied between the mono-crystalline substrate or the epitaxial or mono-oriented thin film disposed on the optical waveguide and according to the applied voltage. An electrode for controlling a light beam in the optical waveguide, which forms a region for deflecting a light beam propagating through the optical waveguide in a first direction in accordance with an applied voltage while changing a refractive index in the optical waveguide; An emission prism that emits the light beam in a second direction that intersects the first direction; and changing the temperature of the optical waveguide, and emitting the light beam from the emission prism in accordance with the temperature. A temperature control means for controlling an emitted light beam for deflecting the light beam to be emitted in the second direction. 2. The temperature control means for controlling the output light beam is a resistor disposed on the optical waveguide near the output prism via a cladding layer having a smaller refractive index than the optical waveguide. 2. The light deflecting element according to claim 1, wherein: 3. The light deflecting element according to claim 1, wherein the temperature control means for controlling the output light beam is a resistor disposed on a side surface near a bottom surface of the output prism. 4. The electrode for controlling a light beam in an optical waveguide,
Has a triangular pattern with two sides that are not parallel to each other,
4. The light deflecting element according to claim 1, wherein a region having a different refractive index corresponding to the triangular pattern is generated by applying a voltage. 5. The triangular polarization domain inversion region having a triangular polarization domain inversion region having two sides that are not parallel to each other, and applying a voltage to a light beam control electrode in the optical waveguide. And generating a different refractive index in a region other than the region.
The light deflecting element according to claim 3. 6. An epitaxial or single-oriented conductive or semiconductive oxide having a lower refractive index than the optical waveguide and provided on a surface of the single crystal substrate. An optical deflecting element according to any one of claims 1 to 5. 7. The optical waveguide is provided on the single-crystal substrate or the epitaxial or single-oriented thin film via a buffer layer having a smaller refractive index than the epitaxial or single-oriented optical waveguide. 7. The optical deflecting element according to claim 1, wherein: 8. The method according to claim 1, wherein the single crystal substrate or the epitaxial or unidirectional thin film is a transparent oxide having a smaller refractive index than the optical waveguide. 3. The light deflecting element according to claim 1. 9. The optical deflection device according to claim 1, wherein a cladding layer having a smaller refractive index than the optical waveguide is provided on a surface of the optical waveguide. element. 10. The optical deflecting element according to claim 1, wherein the optical waveguide is an oxide ferroelectric.