JP6931237B2 - Light deflection device and rider device - Google Patents

Description

The present invention relates to an optical deflection device that controls the traveling direction of light, and a lidar device including the optical deflection device.

The technical fields of laser radar or lidar equipment (LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging)) that use laser measurement to acquire the distance to surrounding objects as a two-dimensional image are the automatic driving of cars and three-dimensional. It is used for map production, etc., and its basic technology can also be applied to laser printers, laser displays, and the like.

In this technical field, a light beam is applied to an object, the reflected light reflected by the object is detected, distance information is obtained from the time difference and frequency difference, and the light beam is two-dimensionally scanned. Acquires wide-angle 3D information.

A light deflection device is essential for light beam scanning. Conventionally, mechanical mechanisms such as rotation of the entire device, mechanical mirrors such as polygon mirrors (polygon mirrors) and galvano mirrors, and small integrated mirrors using micromachine technology (MEMS technology) have been used, but they are large. In recent years, research on non-mechanical light deflection devices has become active due to problems such as high cost and instability in vibrating moving objects.

As a non-mechanical light deflection device, a phased array type or a diffraction grating type that realizes light deflection by changing the wavelength of light or the refractive index of the device has been proposed. However, the phased array type light deflection device has a problem that it is very difficult to adjust the phase of a large number of light radiators arranged in an array and it is not possible to form a high-quality sharp light beam. The diffraction grating type light deflection device can easily form a sharp beam, but has a problem that the light deflection angle is small.

Further, in the light beam to be scanned, in addition to the sharpness described above, controllability of the intensity distribution (amplitude distribution) is required.

Patent Documents 1 to 5 have been proposed, for example, as an optical deflection device having controllability of the beam intensity of a radiation beam.

Patent Document 1 shows a configuration in which the height, width, or depth of the elements constituting the grating is monotonically changed in the waveguide direction of the waveguide light, and Patent Document 2 shows the grating thickness with respect to the propagation direction of the light. In Patent Document 3, a configuration in which the lattice height of the diffraction grating is gradually increased substantially linearly is shown, and in Patent Document 4, the depth of the grating or the thickness of the gap layer is set as the location. Patent Document 5 shows a configuration in which the width of the groove formed on the surface layer of the grating is modulated with respect to the longitudinal direction of the waveguide.

Japanese Patent Application Laid-Open No. 62-296102 Japanese Patent Application Laid-Open No. 4-195003 Japanese Patent Application Laid-Open No. 6-94939 Japanese Patent Application Laid-Open No. 7-169088 JP 2015-161829 Japanese Patent Application No. 2016-10844 (Fig. 10)

The conventionally known light deflection device described above has a configuration in which two components of a waveguide and a light radiation mechanism such as a grating are combined, and is composed of one component in terms of manufacturability, size, cost, and the like. There is a demand for light deflection devices.

Further, in the above-mentioned prior art, a grating (diffraction grating) is used as an optical deflection device, and an intensity distribution (amplitude distribution) is adjusted according to a shape such as height, width, or depth of the grating. Since the surface shape of these gratings requires microfabrication, there are problems such as processing accuracy and variation in shape. Therefore, there is a demand for an optical deflection device that can obtain controllability of an intensity distribution (amplitude distribution) with a configuration that is easy to form.

An object of the light deflection device and the lidar device of the present invention is to solve the above-mentioned problems and to form one component. Another object of the present invention is to make it possible to adjust the intensity distribution (amplitude distribution) by a configuration that is easy to form.

The inventor of the present invention has proposed a technique for increasing the light deflection angle by coupling a slow light waveguide to a diffraction mechanism such as a diffraction grating (Patent Document 6). Slow light occurs in photonic nanostructures such as photonic crystal waveguides and has low group velocities. Slow light light has the characteristic that the propagation constant changes significantly due to slight changes in wavelength and refractive index of the waveguide. When a diffraction mechanism is installed inside or in the immediate vicinity of this slow light waveguide, the slow light waveguide is combined with the diffraction mechanism to form a leak waveguide, which radiates light into free space. At this time, a large change in the propagation constant is reflected in the deflection angle of the synchrotron radiation, and as a result, a large deflection angle is realized.

The light deflection device according to the present invention is based on a photonic crystal having a dual periodic structure in which two types of circular holes having different diameters are repeated along a waveguide.

In a periodic structure in which circular holes of one type of diameter are repeated in the plane of a photonic crystal along a waveguide, slow light propagating light is non-radiating, but a double period in which two types of circular holes of different diameters are repeated. Due to the structure, the slow light propagating light is converted into radiation conditions and radiated into space. Since the double periodic structure has a structure in which two types of circular holes having different diameters are repeatedly provided in the plane of the photonic crystal, it can be composed of one component (Patent Document 6).

Such a double periodic structure includes a periodic structure that repeats a large-diameter circular hole and a periodic structure that repeats a small-diameter circular hole, and the diameter of the reference circular hole is set to 2r and the difference width of the diameter is set to 2Δr. Then, the diameter of the large-diameter circular hole is 2 (r + Δr), and the diameter of the small-diameter circular hole is 2 (r−Δr). Here, the large diameter and the small diameter indicate the relationship between the large and small diameters with respect to the diameter of the reference circular hole or in the comparison of the diameters of each other. The present inventors have found that when Δr is changed in such a configuration, the emissivity changes significantly, but other properties such as the radiation angle and the propagation constant in the propagation direction do not change much.

(Form of light deflection device)
The form of the light deflection device of the present invention is
(A) As the waveguide, a photonic waveguide made of photonic crystals is used instead of the conventional bulk material of glass material or semiconductor material.
(B) As the diffraction mechanism, a photonic crystal structure is used instead of the conventionally proposed grating.
(C) As a diffraction mechanism by the photonic crystal, a structure of a plurality of circular holes formed in the plane of the photonic crystal is provided, and a plurality of circular holes whose diameters change along the waveguide in the plane of the photonic crystal. It has a periodic structure.

The plurality of circular holes provided in the light deflection device of the present invention not only form a waveguide in the plane of the photonic crystal, but also radiate due to a periodic structure in which the diameters of the plurality of circular holes change along the waveguide. The beam intensity distribution (amplitude distribution) is adjusted.

According to the light deflection device of the present invention, the diameter and position of the circular holes in the plane of the photonic crystal can be easily adjusted by the semiconductor film forming technique, so that the light deflection device has an intensity distribution (amplitude distribution). ) Can be obtained with a simple configuration.

(Double periodic structure of circular holes)
The periodic structure of a plurality of circular holes in which a photonic crystal is also formed in the plane of the waveguide of the optical deflection device according to the present invention has a double structure in which the diameters of the circular holes are complementary to each other along the waveguide. It is a periodic structure.

The double periodic structure includes a first periodic structure in which the diameter of the circular hole increases and a second periodic structure in which the diameter of the circular hole decreases. When the diameter of the reference circular hole is 2r and the increase / decrease width of the diameter that increases / decreases complementarily is 2Δr ₁ , 2Δr ₂ .
_{(D) The diameter 2r 1 of the} circular hole included in the first periodic structure is 2 (r + Δr ₁ ).
_{(E) The diameter 2r 2 of the} circular hole included in the second periodic structure is 2 (r−Δr ₂ ).
The diameters of the circular hole diameter 2r _{1 provided by the first periodic structure and the circular hole diameter 2r 2} provided by the second periodic structure are set to the above-mentioned (d) and (e) with respect to the reference circular hole diameter 2r. By making the relationship of, the diameter of the circular hole can be made into a double periodic structure in which the diameter of the circular hole increases and decreases complementarily with each other along the waveguide. Here, the reference circular hole can be arbitrarily set from a plurality of circular holes included in the periodic structure.

(Diameter increase / decrease width Δr ₁ , Δr ₂ )
The diameter increase / decrease widths Δr ₁ and Δr ₂ can be set in a plurality of settings.

[First setting form]
In the first setting mode, the increase / decrease width Δr ₁ and the increase / decrease width Δr ₂ are the same increase / decrease width Δr. According to this setting mode, the diameter 2r ₁ of the circular hole of the first periodic structure increases by 2 (r + Δr), and the diameter 2r ₂ of the circular hole of the second periodic structure decreases by 2 (r−Δr). ..

[Second setting form]
In the second setting mode, the amount of increase in the area of the circular hole provided in the first periodic structure and the amount of decrease in the area of the circular hole provided in the second periodic structure are the same amount.

In a form in which the areas of the circular holes to be increased / decreased are the same, the increase / decrease width Δr ₁ and the increase / decrease width Δr ₂ can be configured by the following relationship.
The relationship between the increase / decrease width Δr ₁ and the increase / decrease width Δr ₂ can be expressed in the following two modes.

First aspect in which the increased / decreased area is the same amount:
The increase / decrease width Δr ₁ and the increase / decrease width Δr ₂ are relative to the reference diameter r.
(R + Δr ₁ ) ² − r ² = r ² − (r − Δr ₂ ) ²
Have a relationship.

Second aspect in which the increased / decreased area is the same amount:
The ratio k (= Δr ₁ / Δr ₂ ) of the increase / decrease width Δr ₁ and the increase _{/ decrease width Δr 2} is relative to the reference diameter r.
k ² + (2r / Δr ₂ ) · k = (2r / Δr ₂ ) -1
Or (1 + 2r / Δr ₁ ) k ^2- (2r / Δr ₁ ) · k = -1
Have a relationship.

(Radiation coefficient and light radiation distribution of light deflection device)
The distribution of light radiation with respect to the propagation direction of the synchrotron radiation emitted from the waveguide to the outside of the plane depends on the intensity of the light propagating in the waveguide of the light deflection device and the radiation coefficient of the light deflection device. In the light deflection device of the present invention, the radiation coefficient can be set according to the increase / decrease state of the diameter of the circular hole of the periodic structure constituting the diffraction mechanism, and further, the light radiation distribution can be set.

In the optical deflection device of the present invention, the propagation light intensity distribution P with respect to the propagation direction of the propagated light of the waveguide, the radiation coefficient B with respect to the propagation direction of the radiated light radiated from the waveguide to the outside of the plane, and the light intensity radiated from the waveguide. Assuming that the light radiation distribution X with respect to the propagation direction of is, the light radiation distribution X is represented by the product (B × P) of the propagated light intensity distribution P and the radiation coefficient B.

From this relationship, the radiation coefficient B of the light deflection device is represented by B = X / P obtained by dividing the light radiation distribution X by the propagation light intensity distribution P. In the light deflection device, since the propagation light intensity distribution along the light propagation direction is determined by the characteristics of the waveguide, the light radiation distribution X can be set by the radiation coefficient B of the light deflection device. Therefore, a desired light radiation distribution X can be obtained by optimally setting the radiation coefficient B.

Here, by using the relationship between the radiation coefficient B and the increase / decrease width Δr of the diameter that changes along the waveguide, the increase / decrease width Δr of the circular hole that gives the optimum radiation coefficient B is determined. Therefore, the desired light radiation distribution X can be obtained by optimally setting Δr.

The light radiation distribution X can have any distribution shape. For example, when the light radiation distribution X is a Gaussian distribution, the synchrotron radiation beam distribution Y with respect to the fluctuation Δθ of the synchrotron radiation angle θ is also a Gaussian distribution, and unnecessary side lobes can be removed.

In the present invention, according to the form of the radiation coefficient set corresponding to the light radiation distribution X, by optimizing the radiation coefficient B, the side lobe and the hemming are reduced, and a higher quality light beam is formed. This can increase the spatial resolution of lidar devices (LiDAR) using light deflection devices. In addition, the adjustment of the radiation coefficient enables a design that minimizes the total loss when the light is restored according to the loss of the slow light waveguide.

The light deflection device of the present invention is characterized in that it has a configuration that enables optimization of the radiation coefficient using a photonic crystal, and the optimization of the radiation coefficient is performed by a conventionally used grating (diffraction grating). It is difficult with a diffraction mechanism such as. The amount of radiation of grating generally changes depending on the depth (height) of the grating. Therefore, in order to change the amount of radiation in the plane, it is necessary to change the depth (height) of the grid depending on the location. It requires a complicated process and it is difficult to obtain high processing accuracy. In addition, changing the depth (height) of the grating lattice changes the diffraction conditions of light, so if the depth is distributed depending on the location, the radiation angle will also have a distribution. Therefore, the beam formed by the synchrotron radiation also has an extra spread. That is, when a grating is used as the diffraction mechanism, the radiation coefficient cannot be optimized while the radiation angles are aligned.

On the other hand, according to the form of the optical deflection device of the present invention, optimization of the radiation coefficient and fixation of the radiation angle can be achieved at the same time only by changing the in-plane design such as adjusting the diameter of the circular hole. .. In addition, the optimization of the radiation coefficient can be realized by easy processing of increasing or decreasing the diameter of the circular hole in the plane along the optical transport path, and has the advantage of realizing high performance. There is.

(Rider device)
The lidar device of the present invention includes the light deflection device of the present invention, a laser light source that emits a plurality of laser beams having different wavelengths, and a light detection unit that individually detects the laser beams. The light deflection device reaches from the outside and an emitter that simultaneously emits laser light of multiple wavelengths emitted by a laser light source in parallel in the direction of each deflection angle determined by the wavelength of each laser light and the refractive index of the beam deflector. Among the laser beams having a plurality of wavelengths, the same element constitutes an injector in which laser beams having an incident angle of which the incident angle is the deflection angle are selectively and simultaneously incident in parallel. The photodetector individually detects the laser light of each wavelength incident at the incident angle having the same deflection angle as the laser light emitted by the emitter in the injector. By matching the deflection angle of the emitter with the deflection angle of the incidenter, the reflected light emitted from the emitter and reflected by the object is detected. By using the light deflection device of the present invention, the lidar device of the present invention can form a desired distribution shape of the light emission distribution of the laser light applied to the irradiation target.

As described above, the optical deflection device and the lidar device of the present invention can realize parallel operation with a simple configuration and avoid an increase in size or complexity of the system.

It is a figure for demonstrating the formation of a synchrotron radiation beam by a leakage waveguide, and the periodic structure which generates a slow light. It is a figure which shows the characteristic of the loss component, the propagation light intensity distribution, the light radiation distribution, and the distribution of a synchrotron radiation beam. It is a figure for demonstrating the structure of the light deflection device of this invention. It is a figure which shows the photonic band, the group refractive index _ng spectrum, the radiation angle θ with respect to a wavelength λ, and the radiation coefficient B _{dB with respect to a wavelength λ.} It is a figure for demonstrating the structure of the light deflection device of this invention. It is a figure for demonstrating the increase / decrease of the diameter of the circular hole of the 1st periodic structure and the 2nd periodic structure. It is a figure for demonstrating the relationship of the propagation light intensity distribution P (y), the radiation coefficient B (y), the light radiation distribution X (y), and the synchrotron radiation beam distribution Y (Δθ) in a light deflection device. It is a figure which shows the propagating light intensity distribution P (y), the radiation coefficient B (y), the light radiation distribution X (y), and the synchrotron radiation beam distribution Y (Δθ). It is a figure which shows the example of the light deflection device when the synchrotron radiation beam is a Gaussian beam. It is a figure for demonstrating the form of the structure of a rider device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In a light deflection device using a slow light structure, FIG. 1 will be used to explain a light emission mechanism using a leak waveguide, and FIGS. 2 to 9 will be used to explain the configuration of the light deflection device of the present invention. The configuration of the rider device of the present invention will be described with reference to 10.

(Synchrotron radiation beam from leaky waveguide)
FIG. 1 is a diagram for explaining the formation of a synchrotron radiation beam by a leakage waveguide and a periodic structure for generating slow light. FIG. 1 (a) shows an outline of radiating light from a leakage waveguide, and FIG. 1 (b) shows an example of using a grating (circuit grating) as a diffraction mechanism.

In FIG. 1A, the incident light incident on the leaky waveguide 10 is radiated from the leaky waveguide 10 as a radiation beam at a deflection angle θ. At this time, the deflection angle θ of the radiated beam changes depending on the wavelength λ of the incident light and the refractive index n of the leakage waveguide.

FIG. 1B shows a configuration example in which a waveguide having a slow light structure and a light radiation mechanism are separate mechanisms in an optical deflection device using a leakage waveguide.

The waveguide 11 of the optical deflection device 1 is a slow light waveguide configured by arranging a second refractive index medium with a period a between the upper clad 11b and the lower clad 11c of the first refractive index medium. 11a is provided. The slow light waveguide 11a forms a periodic structure (periodic structure of the waveguide) by periodically arranging the second refractive index medium with respect to the clad of the refractive index of the first refractive index medium with a period a. As the first refractive index medium, a medium having a higher refractive index than the second refractive index medium can be selected. When light is incident on a periodic structure having a large step formed by deep etching of a material having a large refractive index from a direction propagating in this periodic structure, light (slow light) having a small group velocity is generated. The slow light waveguide 11a propagates incident light incident from one end in a low group velocity slow light mode.

The exit portion 12 of the light deflection device 1 is provided with a light emission mechanism 12a such as a surface diffraction grating at a position adjacent to the upper clad 11b. The light radiation mechanism 12a has, for example, a concavo-convex shape having a period Λ. The concave-convex shape of the period Λ constitutes a periodic structure of the period Λ (periodic structure of the light emission mechanism) between the refractive index n of the refractive index medium and the refractive index n _{out of an external medium such as air.}

Slow light having a periodic structure of the waveguide In the slow light of the waveguide 11a, the propagation constant β changes significantly due to a slight change in the propagation state such as the wavelength λ of light and the refractive index n of the waveguide. Such light propagates while having an electromagnetic field spread (exuding component) around it. When the exit portion 12 having a periodic structure (periodic structure of the light radiation mechanism) having a small step formed by a material having a small refractive index or shallow etching is arranged at a distance that slightly touches the exuding component, Slow light is combined with this to scatter and diffract, and is gradually emitted upward and diagonally. The radiation occurs over a wide area along the direction of the waveguide and is in phase. Therefore, when the light deflection device is viewed from the lateral direction along the propagation direction, the emitted beam becomes a high-quality sharp light beam.

When the wavelength λ of light or the refractive index n of the refractive index medium constituting the periodic structure of the waveguide is changed, the propagation constant β of the waveguide 11 changes, and the coupling condition with the periodic structure of the light emission mechanism of the emission unit 12 changes. change. As a result, the emission angle θ of the emission beam changes.

(Slow light structure by photonic crystal)
An example of forming a two-dimensional photonic crystal in a slow light waveguide will be described with reference to FIG. 1 (c).

In the two-dimensional photonic crystal waveguide 11d of FIG. 1 (c), similar circular holes are arranged two-dimensionally periodically in a semiconductor (Si or the like) slab having the same thickness, for example, in a triangular lattice arrangement. It is a configuration with the circular holes removed. In the structure of the two-dimensional photonic crystal waveguide 11d, a photonic band gap is generated near the Bragg wavelength, the group refractive index _ng is increased, and slow light is generated.

In an optical deflection device using a leakage waveguide, in a configuration in which a slow light structure waveguide and a light radiation mechanism are separate mechanisms, a surface diffraction grating having a periodic structure is provided on the surface of the two-dimensional photonic crystal waveguide 11d. It forms to form a light emission mechanism. By adjusting the thickness of the cladding between the two-dimensional photonic crystal waveguide and the surface diffraction grating, the degree of coupling between the two is changed, and light emission at an appropriate rate is obtained.

(Radiation coefficient of light deflection device, light radiation distribution, synchrotron radiation beam distribution)
In the above-mentioned light deflection device, the waveguide and the light radiation mechanism are composed of individual components, whereas in the light deflection device of the present invention, the waveguide and the light radiation mechanism are formed by the periodic structure of the circular holes. It is a structure with one mechanism. Hereinafter, the outline of the radiation coefficient, the light radiation distribution, and the synchrotron radiation beam distribution of the light deflection device in the periodic structure of the circular hole will be described.

In the waveguide having the slow light structure described above, the slow light gradually leaks to form a synchrotron radiation beam. At this time, if the structure of the waveguide is uniform with respect to the direction in which the light propagates, the radiation coefficient is constant, so that the stronger the intensity of the slow light, the greater the radiation intensity. The intensity of slow light is high at first, and the longer it propagates, the weaker it becomes exponentially due to the influence of radiation and the loss of the waveguide itself. Therefore, the synchrotron radiation beam has a biased intensity distribution in which the synchrotron radiation beam is strong on the front side and weakens in the depth direction even in the same wave surface. When such a synchrotron radiation beam reaches a distant object, the intensity distribution in the near field becomes a Fourier transform distribution. Since the Fourier transform of the exponential distribution is a sinc function, the distribution has many side lobes that attenuate while oscillating from the intensity peak. This reduces the quality of the synchrotron radiation beam, which in turn reduces the spatial resolution of the lidar device (LiDAR).

The intensity distribution of the synchrotron radiation beam described above will be described. The unnecessary loss coefficient of the waveguide is A [cm ^-1 ], the radiation coefficient of light by the light emission mechanism is B [cm ^-1 ], and the propagation light intensity distribution in the waveguide with respect to the traveling distance y is P (y). Then, the following differential equation holds.
dP (y) / dy =-(A + B) P (y) ... (1)

When this equation (1) is solved, the propagated light intensity distribution P (y) and the light radiation distribution X (y) are represented by the following equations (2) and (3), respectively.
P (y) = P ₀ e ^{− (A + B) y}・ ・ ・ (2)
X (y) = BP (y) ・ ・ ・ (3)

Here, assuming that the propagation constant of the waveguide is β, the in-plane wave number k _‖ converted into the optical diffraction mechanism having the period Λ is expressed by the following equation (4).
k _‖ = β− (2π / Λ) N ・ ・ ・ (4)
Here, N is a natural number. In high-order diffraction in which N also takes a large value in Λ, a plurality of radiated beams are generated. Therefore, usually, the first-order diffraction of N = 1 is used.

_{The wave number k ‖} is conserved at the boundary between the device surface and the free space to form a radiation beam, and the following equation (5) holds for the radiation angle θ.
k _‖ ＝ β− (2π / Λ) ＝ k ₀ sinθ ・ ・ ・ (5)

上記式（６）において、ｙ'は放射光ビームの波面に沿った向きに対するｙの射影成分である。Assuming that the amount of deviation of the synchrotron radiation beam emitted in the θ direction from θ is Δθ, the synchrotron radiation beam distribution Y (Δθ) in the distance is given by the following equation (6).

In the above equation (6), y'is a projection component of y with respect to the direction of the synchrotron radiation beam along the wave plane.

The characteristics calculated using the above equations (2), (3), and (6) are shown in FIG. _{A dB} and B _{dB in} FIG. 2A are values obtained by converting the loss coefficient A of the waveguide and the radiation coefficient B of light by the optical radiation mechanism into dB / cm, respectively. Here, both the loss coefficient A and the radiation coefficient B are constant values with respect to the traveling direction of light.

The propagating light intensity distribution P (y) shown in FIG. 2B is a function that decays exponentially, and the light radiation distribution X (y) shown in FIG. 2C also reflects the propagating light intensity distribution P (y). And decay exponentially.

The synchrotron radiation beam distribution Y (Δθ) shown in FIG. 2D is a single peak beam, but the full width at half maximum of Δθ is about 0.04 [deg] °, and side lobes and tailing appear.
Note that FIG. 2 _{shows examples of radiation coefficients B dB} [dB / cm] of 20 dB / cm, 50 dB / cm, and 80 dB / cm.

(Double periodic structure of optical deflection device)
The light deflection device of the present invention has a diffraction mechanism that combines a waveguide and a light radiation mechanism with a single mechanism and a double-period structure with a plurality of circular hole arrays to combine with the propagating light of slow light. The structure is such that the radiation coefficient B of is gradually changed with respect to the traveling direction of light.

Since this double periodic structure does not change the radiation angle of the synchrotron radiation, by adjusting the radiation coefficient B, it is possible to obtain a high quality synchrotron radiation beam as compared with the case where the radiation coefficient B is constant.

The light deflection device of the present invention uses a photonic crystal waveguide as a slow light waveguide, and the waveguide and the light radiation mechanism are configured by one mechanism. The photonic crystal waveguide constitutes a waveguide by reflecting and propagating light by sandwiching the left and right sides of the waveguide with photonic crystals arranged in a circular hole.

The light deflection device according to the present invention is based on providing a double periodic structure in the plane of a photonic crystal, which repeats two types of circular holes having different diameters along the waveguide forming the waveguide.

FIG. 3 is a diagram for explaining the basic principle of the light deflection device according to the present invention (Patent Document 6).
In the light deflection device 1, circular holes 3a and 3b of a low refractive index medium such as _{SiO 2} are arranged two-dimensionally periodically in a slab made of a high refractive index medium such as Si, for example, in a triangular lattice arrangement. The configuration is such that the circular holes in the arrangement of the portions are removed, and the portion from which the circular holes are removed constitutes a waveguide portion made of a two-dimensional photonic crystal and an exit portion that emits a radiated light beam.

The light deflection device 1 includes a double periodic structure 4 that repeats two _{types of circular holes 3a and 3b having different diameters 2r 1} and 2r _{2 with respect to the light propagation direction.} By this double periodic structure 4, slow light propagating light, which is non-radiating in the periodic structure in which circular holes having the same diameter are arranged, is converted into radiation conditions and radiated into space.

The double periodic structure included in the optical deflection device according to the present invention includes a periodic structure that repeats a large-diameter circular hole and a periodic structure that repeats a small-diameter circular hole. When the diameter of the reference circular hole is 2r and the difference width of the diameter is 2Δr, the diameter 2r ₁ of the large-diameter circular hole is 2 (r + Δr), and the diameter 2r ₂ of the small-diameter circular hole is 2 (r−”. Δr). Further, when the distance between the centers of the adjacent large-diameter circular holes 3a and the small-diameter circular holes 3b is a, the distance Λ between the circular holes of each periodic structure is 2a.

An example of the size of the light deflection device 1 is, for example, a = 400 nm, 2r = 210 nm, and the distance s ₃ between the adjacent circular holes 3a and the circular holes 3b is 84 nm. Note that this size is an example and is not limited to this value.

Further, in the configuration example of the optical deflection device shown in FIG. 3, a device using the third row shift type silica clad Si LSPCW and a device using the second row shift type LSPCW can be configured. According to the second row shift type LSPCW having a large ng, an increase in the optical deflection angle Δθ is expected.

4 (a) to 4 (d) show the photonic band, the group refractive index _ng spectrum, the radiation angle θ with respect to the wavelength λ, and the radiation coefficient B _dB with respect to the wavelength λ in the light deflection device of the present invention. .. The radiation angle θ in FIG. 4C is set to θ = 0 ° in the plane vertical direction (z direction in FIG. 3).

In FIG. 4A, in the optical deflection device of the present invention having a dual periodic structure, the photonic band representing the light propagation characteristic has the diameter of the circular hole even when the diameter r of the circular hole changes by 2Δr. Does not change as in the case where is uniform at 2r. Further, even in the group refractive index _{ng , as shown in FIG. 4B, the slow light having a low dispersion of approximately 20 ng} , which does not change with respect to the diameter change Δr, is generated in a wide wavelength band, and is a photonic band. _{It is shown that the ng} increases sharply toward the wavelength corresponding to the edge, and the slow light effect further increases. The characteristic of the light propagation characteristic shows that the propagation constant β does not change with respect to the light propagation direction, and the angle θ of the emitted light does not change as shown in FIG. 4 (c).

On the other hand, in FIG. 4D, the radiation coefficient B _{dB of} light can be changed by changing the diameter 2r of the circular hole by Δr. FIG. 4D shows an example in which Δr is 5 nm, 10 nm, 15 nm, and 20 nm, and shows that the radiation coefficient B _dB increases as Δr increases. The radiation coefficient B represents the rate at which the propagating light leaks out of the plane from the optical transport path, and the larger Δr, the higher the intensity of the synchrotron radiation beam emitted out of the plane. In addition, by adjusting Δr along the light transport path, the intensity of the synchrotron radiation beam emitted out of the plane can be controlled, and the light beam distribution can be adjusted to form a high-quality light beam distribution. Can be done.

At the radiation angle θ with respect to the wavelength λ shown in FIG. 4C, the radiation angle θ reflects the photonic band, so that the Δr dependence is small. Although not shown in FIG. 4C, a light deflection angle Δθ close to 30 ° with respect to a wavelength change Δr = 27 nm can be obtained by the slow light effect and refraction at the silica clad / air interface.

In the radiation coefficient B _dB for wavelength λ shown in FIG. 4 (d), Using n _g large second column shift type LSPCW, further B _dB increase is expected. On the other hand, B _dB increases as Δr increases. Therefore, it is possible to control the amount of light radiation by controlling Δr, and it is possible to form a light radiation beam having a small spread.

As described above, the present inventors have found that when Δr is changed, the emissivity changes significantly, but other properties such as the radiation angle and the propagation constant in the propagation direction do not change so much, which is the object of the present application. We have found that it can be applied to adjust the beam distribution of synchrotron radiation emitted out of the plane to form a high quality light beam distribution.

(Form of light deflection device)
In the form of the light deflection device of the present invention, the diameter changes along the waveguide in the plane of the photonic crystal in the structure of a plurality of circular holes formed in the plane of the photonic crystal as a diffraction mechanism by the photonic crystal. It has a periodic structure of a plurality of circular holes. The plurality of circular holes included in the light deflection device of the present invention constitute a waveguide of conveyed light in the plane of the photonic crystal and a light radiation mechanism for radiating a synchrotron radiation beam out of the plane, and the plurality of circular holes of the plurality of circular holes. The intensity distribution (amplitude distribution) of the radiated beam is adjusted by the periodic structure in which the diameter changes along the waveguide.

FIG. 5A shows a schematic configuration of the form of the light deflection device, and FIG. 5B shows a first periodic structure and a second periodic structure included in the form of the light deflection device.

In FIGS. 5A and 5B, the optical deflection device 1 is provided with periodic structures 4 of a plurality of circular holes 3a and 3b whose diameters change with respect to the light propagation direction on both sides of the waveguide 5. The periodic structure 4 of the plurality of circular holes is a double periodic structure in which the diameters of the circular holes 3a and 3b increase or decrease in a complementary manner along the waveguide 5.

In FIG. 5B, the double periodic structure 4 includes a first periodic structure 4a and a second periodic structure 4b in which the diameter of the circular hole increases or decreases. The increase and decrease in the diameter of the circular holes of the first periodic structure 4a and the second periodic structure 4b are complementary to each other, and when the diameter of the circular hole increases in one periodic structure, it increases in the other periodic structure. The diameter of the circular hole adjacent to the circular hole is reduced. The increase / decrease in the diameter of the circular hole is along the direction of the waveguide 5, but which of the direction in which the propagating light travels in the waveguide 5 or the direction opposite to the direction in which the propagating light travels is used as a reference. Since the direction of increase / decrease is relative, the direction in which the propagating light travels is assumed to be the reference direction, the reference direction is the increase direction, and the direction opposite to the reference is the decrease direction.

In the first periodic structure 4a, the plurality of circular holes 3a _{increase or decrease in diameter 2r 1} with respect to the direction of the propagating light of the waveguide 5. On the other hand, in the second periodic structure 4b, the plurality of circular holes 3b _{decrease or increase the diameter 2r 2} with respect to the direction of the propagating light of the waveguide 5.

FIG. 6 is a diagram for explaining an increase / decrease in the diameter of the circular holes of the first periodic structure and the second periodic structure. In FIG. 6 (a), the diameter of the reference circle hole r, [Delta] r 1 a varying width of the diameter increasing or decreasing _{complementary,} and [Delta] r _2, when a direction from the lower drawing upwards as the reference direction, the first _{The diameter 2r 1} of the circular hole 3a constituting the periodic structure 4a of the above _{increases by 2Δr 1} minute, and becomes 2 (r + Δr ₁ ), 2 (r + 2Δr ₁ ), and so on in that order. _{On the other hand, the diameter 2r 2} of the circular hole 3b constituting the second periodic structure 4b _{decreases by 2Δr 2} minutes, and becomes 2 (r−Δr ₂ ), 2 (r-2Δr _{2), ...}

_{The diameters 2r 1} , 2r ₂ of the circular hole 3a included in the first periodic structure 4a and the circular hole 3b included in the second periodic structure 4b are set to the above-mentioned 2Δr ₁ , By _{increasing / decreasing by 2Δr 2 minutes, the diameters 2r 1} and 2r ₂ of the circular holes 3a and 3b have a double periodic structure in which the diameters 2r 1 and 2r 2 increase and decrease complementarily along the waveguide. The reference circular hole can be arbitrarily set from a plurality of circular holes included in the periodic structure. _{When Δr 1} and Δr ₂ for the increase / decrease are common Δr, the diameters of the circular holes 3a included in the first periodic structure 4a are 2 (r + Δr) and 2 (r + 2Δr), and the second periodic structure The diameter of the circular hole 3b included in 4b is 2 (r−Δr) and 2 (r-2Δr).

In the above description, an example in which the diameter 2r _{1 of the circular hole of the first periodic structure 4a is increased and the diameter 2r 2} of the circular hole of the second periodic structure 4b is decreased has been described. _{The diameter 2r 1} of the circular hole may be decreased and the diameter 2r ₂ of the second periodic structure 4b may be increased.

In the above configuration, it is possible to increase or decrease the amount of radiation of light by increasing or decreasing the [Delta] r ₁ and [Delta] r _2, deviation occurs in the photonic band by increasing or decreasing the [Delta] r ₁ and [Delta] r _2, propagation constant by the position in the optical transport path β and radiation angle θ may change at the same time. As a result, the synchrotron radiation beam is not unified and diffuses in various directions, resulting in a low-quality synchrotron radiation beam.

Here, as a configuration for suppressing fluctuations in the propagation constant β and the radiation angle θ due to the increase / decrease in _{Δr 1} and Δr ₂ described above, the optical deflection device of the present invention has a circular hole when changing _{Δr 1} and Δr _2. It was found that it would be better to have a configuration in which the increase in area and the decrease in the area of the circular hole are equal.

Relationship decrease and become the same amount of area increment and the circular hole in the area of the circular hole is, in relation to the varying width [Delta] r ₁ and varying width [Delta] r _2, the following equation with respect to the reference diameter r ( It can be represented by 7).
(R + Δr ₁ ) ^2- r ² = r ^2- (r-Δr ₂ ) ² ... (7)

FIG. 6B shows a configuration in which the increase and decrease of the areas of the circular holes of the first periodic structure and the circular holes of the second periodic structure of the light deflection device are equal to each other.

The area of the circular hole 3a of the first periodic structure is increased by ΔS ₁ (= (r + Δr ₁ ) ² −r ² ) _{by increasing the diameter from 2r to 2 (r + Δr 1).} On the other hand, the area of the circular hole 3b of the second periodic structure is reduced by ΔS ₂ (= r ^2- (r − Δr ₂ ) ² ) _{by reducing the diameter from 2r to 2 (r−Δr 2).}

By adjusting the increase width Δr ₁ and the decrease width Δr ₂ , the increase / decrease in the areas of _{ΔS 1} and ΔS _{2 is made the same amount. As described above, Δr 1} = Δr ₂ = Δr is configured by making the increase and decrease of each area of the circular hole of the first periodic structure and the circular hole of the second periodic structure equal to each other in the optical deflection device. In comparison with, it is possible to further suppress changes in the photonic band, form a high-quality light beam, and adjust the beam distribution of synchrotron radiation emitted outside the plane, which is the object of the present application. It has been found that it is suitable for forming a high quality light beam distribution.

The relationship in which the increase in the area of the circular hole and the decrease in the area of the circular hole are equal can be expressed by using the ratio k (= Δr ₁ / Δr _{2 ) of the increase / decrease width Δr 1} and the increase _{/ decrease width Δr 2.} .. In this case, the ratio k (= Δr ₁ / Δr _{2 ) of the increase / decrease width Δr 1} and the increase _{/ decrease width Δr 2} can be expressed by the following equation (8) or equation (9) with respect to the reference diameter r. can.
k ² + (2r / Δr ₂ ) · k = (2r / Δr ₂ ) -1 ... (8)
(1 + 2r / Δr ₁ ) k ^2- (2r / Δr ₁ ) ・ k = -1 ・ ・ ・ (9)

(Radiation coefficient and light radiation distribution of light deflection device)
FIG. 7A shows the relationship between the propagation light intensity distribution P (y), the radiation coefficient B (y), the light radiation distribution X (y), and the synchrotron radiation beam distribution Y (Δθ) in the light deflection device. 7 (b) shows the relationship between the radiation coefficient B (y) and the increase / decrease Δr in the diameter of the circular hole. Note that y is the distance from the incident end of the incident light in the waveguide of the optical deflection device.

In the light deflection device of the present invention, the radiation coefficient can be set according to the increase / decrease state of the diameter of the circular hole of the periodic structure constituting the diffraction mechanism, and further, the light radiation distribution can be set.

In the optical deflection device of the present invention, the propagating light intensity distribution P (y) with respect to the propagating direction of the propagating light of the waveguide, the radiation coefficient B (y) with respect to the propagating direction of the radiated light emitted from the waveguide to the outside of the plane, and the waveguide. Assuming that the light radiation distribution X (y) with respect to the propagation direction of the light intensity emitted from the light radiation distribution X (y), the light radiation distribution X (y) depends on the propagated light intensity distribution P (y) and the radiation coefficient B (y), and the light The radiation distribution X (y) is represented by the following equation (10) by the product of the propagated light intensity distribution P (y) and the radiation coefficient B (y).
X (y) = B (y) · P (y) ... (10)

From this relationship, the radiation coefficient B (y) of the light deflection device is expressed by the following equation (11) obtained by dividing the light radiation distribution X (y) by the propagating light intensity distribution P (y).
B (y) = X (y) / P (y) ... (11)

In the light deflection device, since the propagation light intensity distribution along the light propagation direction is determined by the characteristics of the waveguide, the light radiation distribution X (y) can be set by the radiation coefficient B (y) of the light deflection device. Therefore, a desired light radiation distribution X (y) can be obtained by setting the radiation coefficient B (y).

Further, the increase / decrease width Δr of the circular hole of the light deflection device for realizing the desired light radiation distribution X (y) can be obtained based on the relationship between the radiation coefficient B (y) and the increase / decrease width Δr of the diameter. ..

The relationship between the radiation coefficient B (y) and the diameter increase / decrease width Δr can be obtained from the radiation coefficient − diameter change characteristic, and the diameter increase / decrease width Δr is based on the relationship between the radiation coefficient B and the diameter increase / decrease width Δr. , Obtained as a value corresponding to the radiation coefficient B.

The light radiation distribution X (y) can have any distribution shape. For example, when the light radiation distribution X (y) is a Gaussian distribution, the side lobe of the synchrotron radiation beam distribution Y (Δθ) with respect to the fluctuation Δθ of the synchrotron radiation angle θ can be removed.

As shown in FIG. 2, when the radiation coefficient B is constant along the direction of the synchrotron radiation path, the light radiation distribution X (y) is exponentially attenuated, and the side lobe of the synchrotron radiation beam distribution Y (Δθ). Is a sinc function. In order to suppress the side lobes of the light beam, it is conceivable to make the synchrotron radiation beam distribution Y (Δθ) a Gaussian function. In this case, the light radiation distribution X (y) itself needs to be a Gaussian function. The propagating light intensity distribution P (y) is attenuated by the loss coefficient A and the radiation coefficient B of the waveguide. Taking into account the attenuation due to the loss coefficient A and the emission coefficient B, the light emission distribution X (y) is changed along y in order to make it a Gaussian function having a peak in the center of the waveguide of length L. The radiation coefficient B (y) must satisfy the following.
X (y) = B (y) · P (y) = Dexp (−a · (y−L / 2) ² )
... (12)

Here, a is a coefficient that gives the spread of the Gaussian function, and D is a constant that represents the amount of radiation at the peak of the Gaussian function. The differential equation related to propagation based on the equation (12) is expressed by the following equation (13).
dP (y) / dy = -AP (y) -Dexp (-a · (y-L / 2) ² )
... (13)

When the equation (13) is solved, the radiation coefficient B (y) is expressed by the following equation (14).

FIG. 8 shows the calculation results using the above equations (12) and (14), FIG. 8 (a) shows the propagation light intensity distribution P (y), and FIG. 8 (b) shows the radiation coefficient B (y). ), FIG. 8 (c) shows the synchrotron radiation distribution X (y), and FIG. 8 (d) shows the synchrotron radiation beam distribution Y (Δθ).

Here, η is a constant that depends on the constant D, and represents the amount of light that remains unradiated at the position of y = L. Further, f is a constant given by f = a · (L / 2) ^2. For example, f = 0 corresponds to a = 0, and the synchrotron radiation distribution X (y) is a Gaussian function with infinitely small changes. On the other hand, the large constant f corresponds to the large coefficient a, and becomes a Gaussian function with a large change.

FIG. 8 shows (f = 2, η = 0.9), (f = 1, η = 0.95), (f = 1, η = 0.9), (f = 0, η = 0.95). ) And (f = 0, η = 0.9), each case where the loss coefficient A of the waveguide is 0 dB / cm, 10 dB / cm, and 30 dB / cm is shown.

In FIG. 8, the synchrotron radiation beam distribution Y (Δθ) obtained when f = 2 and η = 0.9 indicates that a Gaussian beam having almost no side lobes or tailing is formed.

(Configuration example of optical deflection device)
FIG. 9 shows an example of an optical deflection device when the synchrotron radiation beam is a Gaussian beam. 9 (a) shows a plan view of the light deflection device 1, FIGS. 9 (b) and 9 (c) show a perspective view of the light deflection device 1, and FIG. 9 (c) illustrates the distribution shape of the synchrotron radiation beam. Is shown.

The radiation coefficient B (y) for converting the synchrotron radiation beam into a Gaussian beam is obtained by the equation (14), and further, the diameter of the circular hole forming the distribution shape of the obtained radiation coefficient B (y) is obtained. In order to obtain the diameter of the circular hole, the correspondence relationship between the radiation coefficient B (y) and the increase / decrease width Δr of the diameter of the circular hole formed in the plane of the light deflection device 1 is obtained in advance, and based on this correspondence relationship. , The increase / decrease width Δr of the diameter corresponding to the radiation coefficient B is obtained according to the position of the light deflection device 1 in the light propagation direction. In the configuration example shown in FIG. 9, each diameter of the row of the circular holes 3 provided in the periodic structure 4 of the light deflection device 1 is increased or decreased with respect to the vicinity of the center in the light propagation light direction.

(Form of rider device)
The lidar device of the present invention includes the light deflection device of the present invention, a laser light source that emits a plurality of laser beams having different wavelengths, and a light detection unit that individually detects the laser beams. The light deflection device is an emitter that simultaneously emits laser light of multiple wavelengths emitted by a laser light source in parallel in the direction of each deflection angle determined by the wavelength of each laser light and the refractive index of the waveguide, and a plurality of light deflectors arriving from the outside. Among the laser beams having a wavelength, the same element constitutes an injector in which laser beams having an incident angle of which the incident angle is the deflection angle are selectively and simultaneously incident in parallel. The photodetector individually detects the laser light of each wavelength incident at the incident angle having the same deflection angle as the laser light emitted by the emitter in the injector. By matching the deflection angle of the emitter with the deflection angle of the incidenter, it is possible to detect the reflected light emitted from the emitter and reflected by the object.

Each form of the configuration of the rider device will be described with reference to FIG. The first form of the lidar device is a form in which an injector and an emitter are individually configured. FIG. 10A shows a first form of the rider device. The lidar device 100A of the first embodiment includes an emitter composed of a laser light source 102, a waveguide 104, and a light deflection device 101, and a light deflection device 101, a waveguide 104, and a photodetector 103 (photodiode). It is a configuration in which the constituent injectors are individually provided and juxtaposed. The emitter emits the light of the laser light source 102 toward the outside from the photodetector device 101, and the injector incidents the reflected light that hits the object, passes through a filter (not shown), and then passes through a branch path. It is guided to the light detection unit 103 for detection.

Since the reflected light from an object spreads widely and diffuses, even if the injector is placed next to the emitter, the angle of the light beam received by the injector is slightly different from the emission angle of the emitter. By setting, it is possible to receive the reflected light without directly incident the light emitted from the emitter.

FIG. 10B shows a second form of the rider device. The lidar device 100B of the second embodiment has a configuration in which the waveguide 104 is branched and the photodetector 103 (photodiode) is arranged at one end of the branch path. The light deflection device 101 passes the incident reflected light through a filter (not shown) and then guides the incident reflected light to the photodetector 103 via a branch path for detection.

FIG. 10 (c) shows the third form. In the lidar device 100C of the third embodiment, the optical switch 105 is inserted into the waveguide 104, and after the laser light of the laser light source 102 has passed, the lidar device 100C is switched to the photodetector 103 (photodiode) side, and the laser is reflected and returned. Light is guided to the photodetector 103 (photodiode) with high efficiency.

FIG. 10 (d) shows the fourth form. When a strong reverse bias is applied to a photodiode having a pn junction formed on a Si waveguide, subbandgap absorption occurs through crystal defects, and light in a long wavelength band that cannot be detected originally can be detected. .. In the lidar device 100D of the fourth embodiment, the photodiode having the pn junction formed as the photodetector 103 is inserted in the middle of the waveguide 104, and after the laser light of the laser light source 102 has passed, it is changed to the reverse bias. And detect the reflected light pulse.

FIG. 10 (e) shows the fifth form. The lidar device 100E of the fifth embodiment includes a pulse light source / light detection unit 106 that also serves as a laser light source and a light detection unit. The pulse light source / photodetector 106 can also operate as a photodiode by applying a reverse bias to a semiconductor laser that serves as a pulse light source. According to this configuration, the pulse light source / photodetector 106 emits a laser beam and then applies a reverse bias to operate it as a photodiode to detect the reflected and returned laser beam.

In each form of the lidar device using reflected light, the light from the laser light source can be an optical pulse or continuous light. The lidar device can measure the distance by the TOF method when the optical pulse is used, and can measure the distance by the FMCW method when the continuous light is used.

According to the device configuration of the lidar device of each form, even if light of the same wavelength arrives from a different direction, the incident angle is different, so that the light does not follow the reverse order and is not coupled to the original waveguide, and photodetection is performed. It does not enter the part (photodiode).

In each embodiment shown in FIG. 10, an optical filter of a wavelength filter may be inserted in the waveguide 104. The optical filter is a filter that passes the wavelength of the laser light of the laser light source, and it is more preferable to use a variable wavelength filter that can change the passing wavelength in synchronization with the wavelength change when the wavelength of the laser light source is changed.

There are various wavelengths of light in the environment, and light having a wavelength different from that of the laser light source may arrive at the light deflection device 1 as a noise component. If the angle of incidence of light of different wavelengths and the angle of emission of light beams are the same, noise components with different wavelengths cannot be coupled to the waveguide, but arrive at the light deflection device 1 from a different direction. Some noise components can be coupled back to the waveguide. The optical filter can remove the noise component coupled to the waveguide in this way. The removal of this noise component contributes to the improvement of the SN ratio when detecting the reflected signal of the rider device.

In addition to the configuration using near-infrared light, the technology related to light deflection devices and lidar devices uses visible light such as projectors, laser displays, retinal displays, 2D / 3D printers, POS and card readers by forming devices using visible light materials. It is expected to be applied.

The present invention is not limited to each of the above embodiments. Various modifications can be made based on the gist of the present invention, and these are not excluded from the scope of the present invention.

The light deflection device and lidar device (laser radar) of the present invention are a laser radar (LiDAR) mounted on automobiles, drones, robots, and industrial equipment, a 3D scanner mounted on a personal computer or a smartphone to easily capture the surrounding environment, and monitoring. It can be used for systems. Further, if a similar optical deflection device is used, optical exchange, a spatial matrix optical switch for a data center, and the like are possible.

1 Optical deflection device 2r, 2r ₁ , 2r ₂ Diameter 3,3a, 3b Circular hole 4 Double periodic structure 4a Periodic structure 4b Periodic structure 5 Waveguide 10 Leakage waveguide 11 waveguide 11a Slow light waveguide 11b Upper clad 11c Lower clad 11d 2D photonic crystal waveguide 12 Emission part 12a Light emission mechanism 100A-100E Rider device 101 Light deflection device 102 Laser light source 103 Light detection unit 104 Waveguide 105 Optical switch 106 Pulse light source / light detection part A Loss coefficient B Radiation coefficient D Constant f Constant k Number of waves P Propagation light intensity distribution r Reference diameter X Light radiation distribution Y Radiation light beam distribution

Claims (9)

A light deflection device constructed using photonic crystals.
The photonic crystal includes a waveguide and a double periodic structure composed of a plurality of circular holes provided so as to sandwich the waveguide.
The double periodic structure includes a first periodic structure and a second periodic structure, and the circular holes forming the first periodic structure and the circular holes forming the second periodic structure are the guides. With structures that alternate with each other in the reference direction along the waveguide,
The plurality of circular holes constituting the first periodic structure are configured such that the diameter of the circular holes increases by the first width in the reference direction.
The plurality of circular holes constituting the second periodic structure are configured such that the diameter of the circular holes decreases by the second width in the reference direction.
Light deflection device. 2r diameter of the reference circle hole, and the 2Derutaaru 1 a first _width, when the second width is 2Derutaaru _{2, n} an integer of 0 or more,
_{The diameter 2r 1 of the} circular hole included in the first periodic structure is 2 (r + n · Δr ₁ ).
The light deflection device according to claim 1, _{wherein the diameter 2r 2 of the} circular hole included in the second periodic structure is 2 (rn · Δr _2). The light deflection device according to claim 2, wherein the first width 2Δr ₁ and the second width 2Δr _{2 have the same width 2Δr.} The light deflection device according to claim 2, wherein the amount of increase in the area of the circular hole included in the first periodic structure and the amount of decrease in the area of the circular hole included in the second periodic structure are the same amount. The Δr ₁ , the Δr ₂ , and the r are
(R + Δr ₁ ) ² − r ² = r ² − (r − Δr ₂ ) ²
The light deflection device according to claim 2, wherein the light deflection device comprises the above-mentioned relationship. Wherein [Delta] r ₁ and the [Delta] r ₂ ratio _{k (= Δr 1 / Δr 2} ) , relative to the r,
k ² + (2r / Δr ₂ ) · k = (2r / Δr ₂ ) -1
Or (1 + 2r / Δr ₁ ) k ^2- (2r / Δr ₁ ) · k = -1
The light deflection device according to claim 2, wherein the light deflection device comprises the above-mentioned relationship. Propagation light intensity distribution P with respect to the propagation direction of the propagating light of the waveguide,
Radiation coefficient B with respect to the propagation direction of synchrotron radiation emitted out of the plane from the waveguide,
And the light radiation distribution X with respect to the propagation direction of the light intensity emitted from the waveguide is
B = X / P
With the relationship
The light deflection device according to claim 3, wherein the Δr is a value corresponding to the radiation coefficient B in the relationship between the radiation coefficient B and the Δr. The light deflection device according to claim 7, wherein the light radiation distribution X has a Gaussian distribution. The light deflection device according to any one of claims 1 to 8.
A laser light source that emits multiple laser beams with different wavelengths,
Equipped with a photodetector that individually detects laser light
The light deflection device is
An emitter that simultaneously emits laser light of multiple wavelengths emitted by the laser light source in parallel in the direction of each deflection angle determined by the wavelength of each laser light and the refractive index of the waveguide.
And, among the laser beams of a plurality of wavelengths arriving from the outside, the incidenter in which the laser beams having an incident angle of the deflection angle are selectively and simultaneously incident in parallel is composed of the same element or another element.
The photodetector
A lidar device, characterized in that, in the incidenter, laser light of each wavelength incident at an incident angle having the same deflection angle as the laser light emitted by the emitter is individually detected.

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