JP2010085916A - Light deflector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the number of resolution points of a light deflector. <P>SOLUTION: The light deflector which applies voltage to electro-optic crystal such as KTN (potassium tantalate niobate) to control deflection angle is combined with a thin-layer hologram-waveguide to further increase the number of resolution points of the light deflector alone. In one embodiment, the thin-layer hologram is obtained by forming a grating in a single-mode planar waveguide. This waveguide is configured so as to generate a guided wave whose wavelength vector has the same magnitude as the absolute value of the sum of wavelength vectors of the grating and incident light. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical deflector that changes the traveling direction of light.

  Among optical deflectors that change the traveling direction of light, a KTN optical deflector or a KLTN optical deflector that uses a space charge limited current and a secondary electro-optic effect (Patent Document 1) uses a primary electro-optic effect. The electro-optic light deflector and the acousto-optic light deflector that utilizes ultrasonic waves and the photoelastic effect are solid elements having no movable parts, unlike galvano mirrors, polygon mirrors, MEMS mirrors, and the like. Therefore, when changing the deflection angle, there is no need to accelerate or decelerate the mirror having the inertial mass, and therefore no rigidity is required, so that a small and high-speed optical deflector is obtained. However, these solid-state optical deflectors have the disadvantage that the deflection angle is small and the resolution cannot be increased.

  The number of resolution points referred to in the optical deflector is a value obtained by dividing the light scanning width by the diameter of the light spot. Since the spot diameter also depends on the wavelength of light, the performance index of the deflector alone is given by Φtanθ. Here, Φ is the beam diameter that can enter the optical deflector, and θ is the maximum deflection half angle. The total deflectable angle is 2θ. It is assumed that a convex lens having a focal length f is placed at a distance f from the emission end of the optical deflector. The collimated light emitted from the optical deflector is condensed at a position 2f from the emission end, but the spot size is expressed as approximately 2λf / Φ where the wavelength is λ, and the focal point is moved by 2ftanθ. It becomes a range. That is, the value obtained by dividing the moving range by the spot diameter, Φtanθ / λ, represents the number of resolution points. Since the required wavelength of λ varies depending on the application, Φtanθ, which does not depend on the wavelength, is an index related to the optical deflector.

  For example, as a typical example of a prism-type electro-optic light deflector using the first-order electro-optic effect, ± 15 mrad. For example, when λ is 532 nm, the number of resolution points is 28. Alternatively, as a typical example of a KTN optical deflector using a space charge limited current and a secondary electro-optic effect, ± 125 mrad. Taking the angle of deflection and the beam diameter of 0.5 mm as an example, the resolution is 118 points at λ = 532 nm.

  These solid-state devices, including acousto-optic deflectors that utilize ultrasonic and photoelastic effects, are not used in fields such as printing and display because they do not have a large number of resolution points. Application fields are limited to industrial and research fields.

  By the way, there is known a volume hologram that records a light interference fringe by actually irradiating a light-responsive material such as a photopolymer with a plurality of light beams simultaneously (Patent Document 2).

International Publication No. 2006/137408 Pamphlet Japanese Patent No. 3323146

  The deflection angle itself can be increased by an optical component such as a lens or a diffraction element. However, in the case of a lens, the spread angle of the light beam itself is increased at the same time, so the number of resolution points is unchanged. In the case of a diffraction element, depending on the design of the diffraction grating, in the case of a relief hologram that can be mass-produced, crosstalk is inevitable because diffraction occurs even if the incident angle is changed, resulting in a large number of resolution points. I can't do it. This is due to the more fundamental principle that an optical element that does not contain dissipation does not increase or decrease the information of incident light. This indicates that it cannot be increased.

The present invention uses a method of controlling diffraction according to Bragg conditions with a slight change in incident angle of incident light using a volume multiplexed hologram. The basic principle is to increase the number of resolution points at the expense of continuity of deflection angle. However, since volume multiplex holograms need to form a grating in the depth direction of the hologram medium, there is only a means for recording light interference fringes by actually irradiating multiple light beams simultaneously onto a material that reacts to light such as a photopolymer. unknown. This method is not suitable for mass production, and when N types of a plurality of interference fringes are exposed, the diffraction efficiency is attenuated in proportion to N ⁻² . Therefore, a waveguide hologram produced by mechanically transferring a hologram pattern, which is mass-productive and does not decrease the diffraction efficiency even when the number of types of interference fringes is increased, is used as a volume hologram.

  According to the present invention, it is possible to increase the deflection angle and increase the number of resolution points at the expense of the continuity of the deflection angle of the optical deflection element. Solid mechanical elements such as KTN optical deflectors, electro-optic deflectors, acousto-optic deflectors, which are advantageous in terms of high speed but inferior in the deflection angle range, compared to mechanical optical deflectors such as galvanometer mirrors, polygon mirrors, MEMS mirrors The present invention can be combined. That is, the number of resolution points can be increased by using diffraction by a volume hologram that satisfies the black condition. Furthermore, if the diffraction is not caused by the thin hologram, the incident light intensity is not lost, and diffracted light with high light intensity can be obtained.

  FIG. 1 shows a basic configuration diagram of the present invention. FIG. 1 shows the same viewing direction changed. In FIG. 1A, the light deflection direction is perpendicular to the paper surface, and in FIG. 1B, it is within the paper surface. A collimated incident beam (1-1) having a fixed traveling direction is incident on the KTN optical deflector (1-2). By controlling the voltage applied to the electrode (1-3) provided in the KTN, the beam is deflected in the plane of the paper (xy plane) in FIG. 1 (b). Here, a KTN optical deflector is illustrated as an optical deflector with a small number of resolution points, but a prism type electro-optic light deflector or an acousto-optic light deflector may be used.

  The light (1-4) emitted from the KTN optical deflector (1-2) is condensed (1-6) by the cylindrical lens (1-5), spreads on the xy plane, and is confined in the z direction. The slab waveguide (1-7) has a straight line extending in the y direction by focusing on the end face. The slab waveguide (1-7) includes a core (1-9) sandwiched between clads (1-8) and a waveguide hologram (1- 10). The incident guided light (1-11) coupled to the core (1-9) of the slab waveguide (1-7) is diffracted by the waveguide hologram (1-10) to generate diffracted light (1-12). . If the hologram unevenness size and the waveguide length are designed so that the diffraction efficiency of the waveguide hologram is almost 100% when the Bragg condition is satisfied, the light incident on the waveguide (1-11) is almost Attenuated to 0, only the diffracted light (1-12) is emitted out of the waveguide, is deflected in the xy plane, and becomes emitted light (1-13) that spreads in the z direction. Diffusion in the z direction is returned to parallel by a cylindrical lens (1-14), and collimated light (1-15) deflected to the xy plane is obtained.

  FIG. 2 shows the relationship between incident light, diffracted light, and hologram in the waveguide plane. FIG. 2A shows a pair of incident guided light (2-1), diffracted light (2-2), and waveguide hologram (2-3) in an inverted space. Wave vector of incident guided light (2-1) (

) And wave vector of diffracted light (2-2) (

) Are equal in magnitude (k), ie

And

It is. Here, the effective refractive index (n _eff ) of the waveguide is intermediate between the refractive index of the _core (n _core ) and the refractive index of the _clad (n _clad ), and has a value close to n _core . FIG. 2B shows the same thing in real space, but the traveling direction (2-5) of the incident guided light and the traveling direction (2-4) of the diffracted light are as shown in FIG. The direction of the wave vector is the same. The grating (2-6), which is a hologram, has a wave number vector where the grating pitch is Λ.

The size of

The direction is the direction in which the refractive index of real space changes.

  What is the Bragg condition?

Is to satisfy. Here, the sign may be positive or negative. When the Bragg condition is satisfied, the diffraction efficiency (η) is

It is represented by Here, δn is the amplitude of the refractive index modulation of the grating, L is the interaction length between the grating and the incident light, and θ is the angle formed by the grating vector and the wave number vector of the incident light.

  In order to realize “increasing the number of resolution points” which is the object of the present invention, a plurality of gratings are superimposed as shown in FIGS. 2C and 2D, and the direction of incident guided light is made minute. When changed, the grating satisfying the Bragg condition changes to Grating 1 (2-7, 2-10), Grating 2 (2-8, 2-12), Grating 3 (2-9, 2-11), The direction of the diffracted light to be diffracted needs to change one after another. FIG. 2C shows a waveguide hologram composed of a plurality of gratings 1, 2 and 3 in an inverted space, and FIG. 2D shows a real space.

  However, in the present invention, since the grating is a waveguide hologram formed in the core clad interface of the waveguide, the wave number vector of the grating has no z component and is in the xy plane. This leads to a situation different from a normal volume multiplex hologram.

FIG. 3 is a diagram for explaining diffraction of a waveguide hologram in an inverse space. FIG. 3A is a diagram of the inverted space when the waveguide surface is viewed from above, and FIG. 3B is a diagram of the inverted space when the waveguide surface is viewed from the side. The wave number vectors of the grating are all in the xy plane. Reference numeral (3-1) indicates the surface of the Ewald sphere having a radius of 2πn _eff / λ. Wave vector of incident guided light

Let's say. Three types of grating vectors, where P is the starting point of the grating vector in the xy plane

think of. The point A is on the Ewald sphere in the xy plane including the zero point. The normal of the xy plane starting from point B intersects the Ewald sphere (3-1) at the intersection (B '). Here, B 'point is

And the angle θ between the z axis and

It shall be in the area | region (3-2) which satisfy | fills. On the other hand, the intersection C ′ between the normal line starting from the point C and the Ewald sphere (3-1) is assumed to be outside the region (3-2) that satisfies the equation (5).

  Volume multiplexed holograms using waveguide holograms intended in the present invention are:

Incident,

Diffracted by

Produces diffracted light having a wave vector of.

Is in the xy plane. That is, diffracted light is also guided light.

  Because point B is not on the Ewald sphere,

Respectively

If the volume hologram does not satisfy the Bragg condition, the expression (3) should not cause diffraction. However, when the point B ′ is included in the region (3-2) in FIG.

Diffracted light having a vector as a wave vector is generated. this is,

As a thin-film hologram

It is the result of acting on. On the other hand, when the point C ′ is outside the region (3-2),

Light having a wave vector of is confined in the waveguide. Therefore,

Is prohibited as a wave vector because of its waveguide structure.

Since the wave vector of is forbidden by the law of conservation of energy,

Is

It will not be diffracted by.

In FIG. 4, the operation of the plurality of gratings will be described. The figure is drawn in an inverse space on the waveguide plane (z = 0). Reference numeral (4-1) denotes a circle having a radius of 2πn _eff / λ, and is an intersection line with z = 0 of the Ewald sphere (3-1) in FIG. The wave vector of the incident light to the two types of waveguides

And Since A ₁ and B ₂ are on the circle (4-1),

Respectively

And

Respectively

Since the expression (3) of the Bragg condition is satisfied,

and

Produces diffracted light having a wave vector of.

Produced diffraction for OP ₂

, When the start point P ₁ moves parallel, because the end point B ₁ represents fall outside of the Ewald sphere,

Does not act on the incident light.

  But,

Caused diffraction

Is translating to when the combined start point _{P 2,} since the end point _{A 2} enters the disk of radius _{2πn eff n clad / n core λ} (4-2) in the same effect as the point B in FIG. 3 Happened,

Acts as a thin film hologram that diffracts out of the waveguide. Therefore,

Even if both types of gratings act on the incident light, and the diffraction out of the waveguide is shielded as unnecessary, the necessary diffraction in the waveguide plane

Will be diminished. Therefore, when multiplexing the gratings, it is necessary to select a grating to be acted upon so as not to cause diffraction by such a thin film hologram.

  FIG. 5 shows the traveling direction (front to back) of the incident light to the waveguide and the outgoing light from the waveguide. FIG. 5A shows the leftmost incidence and diffraction satisfying the Bragg condition, and FIG. 5B shows the second incidence and diffraction from the right satisfying the Bragg condition. FIG. 5C shows the incidence and diffraction from the left most satisfying the Bragg condition, and FIG. 5D shows the incidence and diffraction not satisfying the Bragg condition.

  Reference numeral (5-1) denotes an angle range in the traveling direction that the light incident on the waveguide can take. Within that angle range, there is a grating that satisfies the Bragg condition at the angle at which the scale (5-2) was struck, and it was struck by the scale (5-4) within the angle range indicated by reference numeral (5-3). Make diffraction at the angle. At the angular interval at which the scale (5-2) is struck, the beams (5-5) and (5-7) are not separated on the projection plane in FIGS. 5 (a) and 5 (b), but are diffracted by the waveguide hologram. In this case, the interval between the scales (5-4) is widened so that the beam (5-6) and the beam (5-8) can be separated from each other on the projection plane. In FIG. 5C, when the incident beam (5-9) is tilted to the right, the angle of the diffracted light (5-10) is tilted to the left. In this explanation, the inclination of the incident light and the inclination of the diffracted light are opposite, but this is not necessarily required. However, by making the incident light and the diffracted light in opposite directions, a configuration in which a thin film hologram does not easily occur can be obtained.

  FIG. 5D shows a situation when the incident beam (5-11) is incident at an angle that does not satisfy the Bragg condition. The angular resolution (δθ) with respect to the incident angle in a waveguide under Bragg conditions is

It is represented by Here, L is the interaction length between the guided light and the grating, and θ is the angle formed by the grating vector and the wave vector of the guided light. When L is sufficiently long and the deviation of the incident angle from the Bragg condition is larger than δθ expressed by equation (6), diffraction does not occur. However, when L is short, a plurality of weak diffractions are generated by a plurality of gratings close to the Bragg condition, and a plurality of beams are generated as shown in (5-12).

  In the present invention, since the hologram principle is used, the phase of the incident light needs to be uniquely determined. Therefore, the waveguide must be single mode. Therefore, the core thickness (d) is

Must. For example, when λ = 650 nm, n _core = 1.52, and n _clad = 1.50, d <1.32 μm. To couple the beam to such a narrow core, either align the system tightly and then fix it so that it does not move, or allow the beam to change to the core position. It is necessary to form.

  FIG. 6 shows a configuration when the latter method is adopted. FIG. 6A is a view of the laminated waveguide as seen from the cross-sectional direction, and FIG. 6B is a view of the laminated waveguide as seen from above. A KTN deflector (6-5) in which an electrode (6-6) for deflecting the beam in the xz plane is formed in order to control the beam condensed linearly by the cylindrical lens along the core. Use. The incident beam (6-1) is deflected in the xy plane by the KTN deflector (6-2) on which the electrode (6-3) is formed, and then deflected by the λ / 2 plate (6-17). After rotating the surface by 90 °, the light enters the aforementioned KTN deflector (6-5). The beam (6-7) that has passed through the two KTN deflectors is deflected two-dimensionally and is condensed linearly by the cylindrical lens (6-8). Since the position of the condensing line in the z direction can be changed by the KTN deflector (6-5), the voltage applied to the electrode (6-6) may be adjusted so that the coupling efficiency to the core is increased.

  In FIG. 6, a laminated waveguide (6-10) is used. Since the position of the beam in the z direction can be modulated, if waveguides are stacked, deflection in the xz plane can be performed by selecting a waveguide layer to be coupled. If a gap (6-16) is provided on the output end side of the waveguide, the deflection angle in the xz plane can be increased. However, regarding the deflection in the xz plane, the number of resolution points is not increased, and if only the deflection angle is changed, it is possible to change the focal length of the cylindrical lens (6-14). 16) is not necessarily required. Thus, by adding a KTN deflector (6-5) that enables deflection in the xz plane, a means for increasing the coupling to the waveguide can be provided. Further, by laminating, it is possible to select a grating that does not cause diffraction by a thin-layer hologram.

  Next, FIG. 7 shows a method for ensuring the coupling of incident light (7-1) to the waveguide (7-2). Also in this figure, a gap is provided between the waveguides, but such a gap is not always necessary, and the waveguides can be simply laminated. In FIG. 7, the slab waveguide (7-2) is illustrated as being stacked, but the waveguides are not necessarily stacked. A region (7-3) in which a grating causing diffraction outside the waveguide is drawn in the waveguide, and a light receiving element (7-9) that can detect the light intensity of the diffracted light (7-7) diffracted outside the waveguide ). The grating for generating diffraction outside the waveguide is shown in FIG.

It is a grating with a wave vector. Since the diffracted light is diffracted by the grating in the normal direction of the waveguide surface, a voltage that maximizes the amount of light received by the light receiving element (7-9) may be applied to the electrode (6-6). By providing this region (7-3) before the diffraction region (7-4) in the waveguide which is the core of the present invention, the fluctuation width in the traveling direction of the incident waveguide is small. The deflection angle of the emission angle of (7-7) is also reduced, and there is an advantage that the light receiving area of the light receiving element (7-9) can be reduced.

  Furthermore, by providing a grating (7-5, 7-6) and a light receiving element group (7-10) for generating diffraction (7-8) outside the waveguide for the diffracted light in the waveguide, It is possible to monitor and compensate for the installation angle error between the KTN deflector and the waveguide and the deterioration of the KTN deflector. It should be noted that the grating region (7-2, 7-5, 7-5) for monitoring is not used in order to prevent the amount of light emitted from the waveguide end (7-11, 7-12, 7-13, 7-14) from being finally reduced. The diffraction efficiency of 7-6) needs to be small. Specifically, the control is performed by shortening the width of the grating (the length in the x direction).

  In the present invention, since the principle of volume hologram is used, the diffraction efficiency can be 100% as shown in the equation (4). However, it is difficult to always compensate 100% diffraction efficiency due to various factors such as thermal expansion and misalignment. In that case, both incident light and diffracted light are emitted from the end of the waveguide, which may be problematic depending on the application. Therefore, a device for blocking incident light is made at a diffraction efficiency of 100% or less.

  FIG. 8 is a diagram for explaining a method of removing incident light when the diffraction efficiency is not 100%. In FIG. 8A, the first-layer slab waveguide (8-1) generates diffracted light at the diffraction angle of (8-3) with respect to the incident angle range of (8-2). . The second layer slab waveguide (8-4) causes diffraction in the region (8-5) opposite to the first layer for the same incident angle (8-2). FIG. 8B shows a waveguide (8-6) in which these two waveguides are laminated. By selecting the incident waveguide, the range of diffracted light is changed from (8-3) to (8- 5) can be expanded. However, in the state (A) in which the layers are simply laminated, in the case of diffraction efficiency of 100% or less, the incident light, which is zero-order light, is emitted (8-2) with a small amount of light, and thus crosstalk occurs.

  Therefore, in FIG. 8C, the 0th-order light is removed regardless of the diffraction efficiency by adding the light shielding plate (8-7) that blocks the 0th-order light. However, in this configuration, a state where light is not deflected so much becomes a blind spot. Therefore, in FIG. 8D, it is possible to eliminate the blind spot within the deflection angle range by adding the prism (8-8).

  Example 1 will be described with reference to FIGS. 1 and 9. FIG. 9 is a diagram of the waveguide as viewed from above, and is a diagram for explaining a configuration of a plurality of gratings on the waveguide.

  The used light (1-1) is collimated laser light having a wavelength of 830 nm. The deflection angle of the KTN optical deflector (1-2) is ± 5 °, and the beam diameter is 0.5 mmφ. Since Φtanθ = 0.0437 mm, the number of resolution points with the KTN optical deflector alone is 52 at λ = 830 nm.

  If the refractive indexes of the core and clad of the waveguide (1-7) are 1.53 and 1.50, respectively, the numerical aperture of the waveguide is NA = 0.3, so that the cylindrical lens (1-5) The focal length is 1 mm, and the lens NA is set to NA = 0.24, which is slightly lower than the NA of the waveguide. The thickness of the core is set to 1.2 μm, which is slightly smaller than the single mode condition of 1.38 μm. The width of the condensing line by the cylindrical lens is 3.46 μm, and the focal depth is ± 7.2 μm. Therefore, alignment of the incident end faces of the cylindrical lens (1-5) and the waveguide (1-7) is performed with a precision of ± 5 μm using a microscope.

  The deflection angle of the incident guided light is ± 3.27 ° according to Snell's law. If 260 resolution points are required, a deflection width of 50 ° is required outside the waveguide, and the object can be achieved if it can be converted to a deflection angle of 5 ° to 33.5 ° inside the waveguide. The grating periodically arranges grooves having a depth of 50 nm and a width of 70 nm so as to form a required grating vector. However, when a plurality of gratings are superimposed, the depth of the portion where the grooves overlap is not changed. Unify to 70 nm. Furthermore, as shown in FIG. 9, gratings (9-5 to 9-8) in which the diffraction order regions are divided are produced.

The angle φ _m in the waveguide of the m-th diffracted light is set at a constant angle interval outside the waveguide.

And Here, m is an integer from 0 to 259. On the other hand, the angle [Phi _m in the waveguide of the incident light corresponding to phi _{m is, ΔΦ m = Φ m + 1} -Φ m, Φ 0 = -3.27 °, as Φ ₂₅₉ = 3.27 °, recurrence formula

The coefficient A is determined so as to satisfy For example, the calculated value of A is A = 0.00003650934146.

  Grating vector contributing to each diffraction

Is

The period of the mth grating is given by

And the direction of each groove extends in the direction perpendicular to the grating vector in the waveguide plane. The period (Λ) of the grating ranges from 0.8 μm for m = 0 to 17.96 μm for m = 259.

Next, the position for drawing the grating is changed according to m. As shown in FIG. 9, here, assuming that the incident end of a slab waveguide having a waveguide surface with an area of 15 × 20 mm ² is x = 0, a grating (9-8) of 0 ≦ m <65 is 2 mm <x <4 mm position, 65 ≦ m <130 grating (9-7), 4 mm <x <6 mm position, 130 ≦ m <195 grating (9-6), 6 mm <x <8 mm position In addition, a grating (9-5) of 195 ≦ m <260 is drawn by superimposing each on a position of 8 mm <x <10 mm. However, each groove of the grating is not a groove connected in the region x, but is composed of a random length with a minimum length of 4 μm and a broken line of a random gap, and the line coverage (ζ) is a unit of Λ. As μm ζ = 0.05Λ (11)
To be. In FIG. 9, the diffracted light is emitted in the direction of (9-4) with respect to the incident light (9-2), and if the diffraction efficiency is not 100%, the 0th-order light (9-3) is emitted. Is done. In this way, it is possible to prevent the thin-layer hologram diffraction from occurring by arranging the grating separately for each diffraction order. Note that the direction of diffracted light in the waveguide changes according to the equation (10).

  When a pattern in which the grating pattern shown in FIG. 9 of the first embodiment is vertically inverted on the paper surface is produced, diffraction by the grating (9-9) occurs in the (9-10) direction as shown in FIG. 10 (a). . When the laminated waveguide (9-11) is manufactured by arranging FIG. 9 in the first layer and FIG. 10 (a) in the second layer and setting the cladding thickness separating the cores to 10 μm, FIG. 9 (b) As shown, the deflection range (9-13) is expanded by layer selection, and the number of resolution points increases to 520, which is twice the 260 points. FIG. 9B illustrates a configuration in which a shielding plate (9-12) of 0.5 mm width × 0.1 mm height that shields the 0th-order light is arranged to shield the remaining 0th-order light.

  Furthermore, in the range of 1 mm <x <1.5 mm, the wave vector

But

A grating (9-14) is formed. Since the diffracted light from the grating (9-14) is diffracted in the vertical vertical direction of the waveguide, it is possible to maximize the coupling to the waveguide by receiving this light at the light receiving element and performing a peak search. Become.

While the present invention has been described with respect to several specific embodiments, the embodiments described herein are merely illustrative in view of the many possible embodiments to which the principles of the present invention can be applied. It is not intended to limit the scope of the invention. For example, in the above-described embodiment, the KTN deflector is used as the deflector. However, as in the case of KTN, LLTN (K _1-y Li _y Ta) that uses a space charge limiting current and a secondary electro-optic effect is used. _1-x Nb _x O ₃ ) can be used, and the primary electro-optic effect using LN (LiNbO ₃ ), BT (BaTiO ₃ ), SBN (Sr _1-x Ba _x Nb ₂ O ₆ ) can be used. A prism-type electro-optic light deflector to be used can also be used. As described above, the configuration and details of the embodiment exemplified here can be changed without departing from the gist of the present invention. Further, the illustrative components and procedures may be changed, supplemented, or changed in order without departing from the spirit of the invention.

It is a figure which shows the basic composition of this invention, Fig.1 (a) is the figure seen from the cross-sectional direction of the waveguide, FIG.1 (b) is the figure which looked at the waveguide surface from the top. It is a figure which shows the relationship between the incident light in the waveguide surface which has a grating, a diffracted light, and a waveguide hologram, and Fig.2 (a) is a figure which showed incident light, the diffracted light, and the waveguide hologram in reverse space 2 (b) is a diagram showing incident light, diffracted light, and a waveguide hologram in real space, and FIG. 2 (c) is a diagram showing a waveguide hologram composed of a plurality of gratings in reverse space. FIG. 2D is a diagram showing a waveguide hologram composed of a plurality of gratings in real space. FIG. 3A is a diagram for explaining diffraction of a waveguide hologram in an inverse space, FIG. 3A is a diagram of the inverse space when the waveguide surface is viewed from above, and FIG. 3B is a diagram when the waveguide surface is viewed from the side. FIG. It is a figure explaining the multiple hologram in a waveguide hologram in reverse space. It is a figure which shows the advancing direction of the incident light to a waveguide, and the emitted light from a waveguide, Fig.5 (a) shows the incident light and diffracted light from the right most satisfying Bragg conditions, and FIG.5 (b) is FIG. The second incident light and diffracted light from the right satisfying the Bragg condition are shown, FIG. 5C shows the leftmost incident light and diffracted light satisfying the Bragg condition, and FIG. 5D does not satisfy the Bragg condition. It is a figure which shows incident light and diffracted light. FIG. 6 is a diagram showing a configuration in which a beam of incident light is incident on a waveguide core in the present invention, FIG. 6A is a diagram viewed from the cross-sectional direction of the waveguide, and FIG. It is the figure which looked at the waveguide surface from the top. FIG. 7A is a diagram showing a configuration for monitoring the intensity at which an incident light beam is coupled to a waveguide in the present invention, and FIG. 7A is a diagram seen from the cross-sectional direction of the waveguide, and FIG. ) Is a view of the waveguide surface as viewed from above. FIG. 8A is a diagram for explaining a method of removing incident light when the diffraction efficiency is not 100% in the present invention, and FIG. 8A shows the incident angle ranges of incident light of the first and second layers. FIG. 8B shows the diffraction angle range of the diffracted light, FIG. 8B shows the diffraction angle range of the diffracted light with respect to the incident angle range of the incident light when the first layer and the second layer are combined, and FIG. FIG. 8 (d) shows a configuration in which a prism is further added. FIG. It is a figure for demonstrating Example 1 of this invention. It is a figure for demonstrating Example 2 of this invention.

Explanation of symbols

1-1 Incident beam 1-2 Optical deflector 1-3 Electrode 1-4 Emission light 1-5 Cylindrical lens 1-6 Condensed beam 1-7 Slab waveguide 1-8 Clad 1-9 Core 1-10 Waveguide Hologram 1-11 Incident guided light 1-12 Diffracted light 1-13 Outgoing light 1-14 Cylindrical lens 1-15 Collimated light 2-1 Incident guided light 2-2 Diffracted light 2-3 Waveguide hologram 2-4 Traveling direction 2-5 Traveling direction of incident guided light 2-6, 2-7, 2-8, 2-9, 2-10, 2-11, 2-12 Grating 3-1 Ewald sphere 3-2 Region 4- 1 Circle 4-2 Disc 5-1 Angle range of traveling direction that incident light can take 5-2 Scale indicating existence of grating satisfying Bragg condition 5-3 Angle range for generating diffraction 5-4 Scale for generating diffraction 5- 5,5 -6, 5-7, 5-8 beam 5-9 incident beam 5-10 diffracted light 5-11 incident beam 5-12 multiple beams 6-1 incident beam 6-2 deflector 6-3 electrode 6-4 deflection 6-5 Deflector 6-6 Electrode 6-7 Beam 6-8 Cylindrical lens 6-9 Condensed beam 6-10 Laminated waveguide 6-11 Incoming waveguide light 6-12 Diffracted light 6-13 Outgoing light 6-6 14 Cylindrical lens 6-15 Collimated light 6-16 Gap 6-17 Half-wave plate 7-1 Incident light 7-2 Waveguide 7-3 Region where grating that causes diffraction outside the waveguide is drawn 7-4 Inside the waveguide 7-5 Grating 7-7 that produces diffraction outside the waveguide 7-6 Grating that produces diffraction outside the waveguide 7-7, 7-8 Diffracted light diffracted outside the waveguide 7-9 Light receiving element 7- 10 Light receiving element group 7-11, 7-12, 7-13, 7-14 Emission light 8-1 Slab waveguide 8-2 Incident angle range 8-3 Diffraction angle range 8-4 Slab waveguide 8-5 Diffraction angle range 8-6 Multilayer waveguide 8-7 Light shielding plate 8-8 Prism 8-9, 8-10 Diffraction angle range 9-1 Slab waveguide 9-2 Incident light 9-3 0th order light 9-4 Direction of diffracted light 9 -5, 9-6, 9-7, 9-8 Grating region 9-9 Grating region group 9-10 Direction of diffracted light 9-11 Multilayer waveguide 9-12 Shielding plate 9-13 Deflection range 9-14 Grating region

Claims (10)

An optical deflector that changes the traveling direction of light,
A planar waveguide that is single mode for incident light;
Deflection means for changing a horizontal incident angle of the incident light with respect to the planar waveguide,
The planar waveguide includes a grating having a wave vector Ki in the waveguide, where i is the diffraction order,
The grating is configured such that there is guided light having a wave vector k _s having a magnitude equal to the absolute value of the sum of the wave vector Ki and the wave vector k _r of the incident light. Optical deflector. The optical deflector according to claim 1, comprising:
The planar waveguide includes a diffracting means for diffracting a part of the guided light out of the waveguide. The optical deflector according to claim 2, wherein
The planar deflector further comprises light receiving means for detecting light diffracted outside the waveguide. The optical deflector according to claim 3, wherein
A second deflecting unit that changes an incident angle of the incident light in a vertical direction with respect to the planar waveguide;
The optical deflector, wherein the incident angle in the vertical direction is configured to be changed by the second deflecting unit based on the intensity of light detected by the light receiving unit. The optical deflector according to any one of claims 1 to 4,
In the grating, the projection of the end point of the vector obtained by adding the wave vector Ki and the wave vector k _s of the guided light onto the Evalt sphere gives the refractive indices of the core and clad of the planar waveguide to n. as _core and _{n clad, n} core _{sinθ <optical} deflector, characterized in that it is configured so as to satisfy _{n clad.} An optical deflector according to any one of claims 1 to 5,
An optical deflector comprising a plurality of the planar waveguides laminated. The optical deflector according to any one of claims 1 to 6,
An optical deflector using KTN or KLTN as the deflecting means. The optical deflector according to any one of claims 1 to 6,
An optical deflector using LN, BT, or SBN as the deflecting means. The optical deflector according to any one of claims 1 to 6,
An optical deflector using an acousto-optic light deflector utilizing ultrasonic waves and a photoelastic effect as the deflecting means. The optical deflector according to any one of claims 1 to 6,
The planar waveguide includes at least one of a prism and a light shielding plate on an emission end face thereof.

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