JP2018173537A - Optical waveguide device and laser radar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical waveguide device that is used for a laser radar, the optical waveguide device having strong resistance against high intensity light.SOLUTION: An optical waveguide device comprises: an optical waveguide core; and a clad that covers the optical waveguide core. The optical waveguide core includes a first input/output part and a second input/output part that are formed along a common reference plane, an array waveguide part that includes a plurality of fine-line waveguides connecting the first input/output part with second input/output part in parallel, and refractive index control parts that are provided in the middle of the fine-line waveguides. The first input/output part is a grating coupler or a spot size converter. The refractive index control parts give phase shift with different amounts of shift to rays of light propagating through the fine-line waveguides. The second input/output part couples the light propagating in a direction along the reference plane and the light propagating in a direction intersecting the reference plane.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical waveguide element used for laser radar, and a laser radar including the optical waveguide element.

  Laser radars have been developed that detect the size, shape, or distance from an object by sweeping laser light, irradiating the object, and receiving the reflected light. In addition, a technique of using an optical waveguide element using, for example, silicon (Si) as a waveguide material for a transmitter and a receiver of a laser radar has been studied (see, for example, Patent Documents 1 and 2).

  In a laser radar using an optical waveguide element, the transmission unit includes a demultiplexing unit and an arrayed waveguide unit configured by the optical waveguide element. The arrayed waveguide portion includes a plurality of thin wire waveguides, and the plurality of thin wire waveguides are connected in parallel with the branching portion.

  In a laser radar using an optical waveguide element, a laser beam is demultiplexed into a plurality of beams at a demultiplexing unit. The demultiplexed laser beams are respectively input to different thin wire waveguides in the arrayed waveguide portion. In the arrayed waveguide portion, a phase shift with a different shift amount is given to the laser light propagating through each thin wire waveguide (that is, the phase is controlled). And the laser beam output from each thin wire | line waveguide is multiplexed, and the light beam as irradiation light with respect to a target object is formed.

  In the laser radar using the optical waveguide element, the traveling direction of the irradiation light can be controlled by controlling the phase of the laser light in the arrayed waveguide portion. Therefore, it is not necessary to provide a movable part in the apparatus when controlling the traveling direction of the irradiation light. As a result, for example, when a laser radar is mounted on a vehicle, resistance to vibration is improved, so that a laser radar having excellent reliability can be realized.

Here, in an optical waveguide element (Si waveguide) using Si as a waveguide material, an optical waveguide core that substantially becomes a light transmission path is formed using Si as a material. Then, the periphery of the optical waveguide core is covered with a clad made of, for example, silicon oxide (SiO ₂ ) having a refractive index lower than that of Si. With such a configuration, in the Si waveguide, the refractive index difference between the optical waveguide core and the clad becomes extremely large, so that light can be strongly confined in the optical waveguide core. As a result, in the Si waveguide, the size of the optical waveguide can be reduced. Further, in the Si waveguide, a small curved waveguide having a bending radius reduced to, for example, about several μm can be realized. Therefore, using the Si waveguide for laser radar is advantageous for downsizing the entire apparatus. Furthermore, Si has a large temperature coefficient. For this reason, for example, when phase control is performed by a thermo-optic effect using an electrode, it is possible to perform phase control with small electric power.

US Patent No. 2015/0378241 US 2016/0049765

  By the way, in a laser radar, when using for the object which detects a far object, it is necessary to use a strong light pulse as a laser beam. However, in the laser radar using the optical waveguide element, when high intensity light is input to the Si waveguide having a small size, there is a problem that the optical waveguide element itself is damaged and deteriorated due to the influence of two-photon absorption.

  An object of the present invention is to provide an optical waveguide element used for laser radar, which is highly resistant to high-intensity light, and a laser radar including the same.

  In order to solve the above-described problems, an optical waveguide device according to the present invention includes an optical waveguide core and a clad including the optical waveguide core. The optical waveguide core includes a plurality of first input / output units, a second input / output unit, and a first input / output unit and a second input / output unit that are formed along a common reference plane. It includes an arrayed waveguide portion including a thin wire waveguide, and a refractive index control portion provided in the middle of each thin wire waveguide. The first input / output unit is a grating coupler or a spot size converter. Each refractive index control unit gives a phase shift of a different shift amount to light propagating through the thin wire waveguide. The second input / output unit couples light propagating in a direction along the reference plane and light propagating in a direction intersecting the reference plane.

  In the optical waveguide device of the present invention, light from a light emitting device such as a pulse light source can be input to each thin wire waveguide via the first input / output unit. And according to the intensity | strength of the light from a light emitting element, and the tolerance of a thin wire waveguide, the installation number of a thin wire waveguide is determined, and light is branched. For this reason, unlike the case where the light from the light emitting element is directly input to the thin waveguide having a small size, the optical waveguide element of the present invention can suppress the two-photon absorption. Therefore, the optical waveguide device of the present invention has high resistance to high-intensity light, and can prevent the problem of deterioration of the optical waveguide even when it is used, for example, in a laser radar transmitter.

(A) is a schematic plan view showing an optical waveguide device of the present invention, and (B) is a schematic end view of the structure shown in (A) taken along line II. (A) is a schematic end view for explaining the first input / output unit, and (B) and (C) are schematic plan views for explaining the first input / output unit. 1 is a schematic plan view showing a first laser radar of the present invention. It is a figure which shows the 1st laser radar of this invention, and is the schematic side view which looked at the structure shown in FIG. 3 from the left side of the paper surface. It is a schematic plan view which shows the 2nd laser radar of this invention. (A) is the schematic side view which looked at the structure shown in FIG. 5 from the left side of a paper surface, (B) is the schematic side view which looked at the structure shown in FIG. 5 from the paper surface lower side. . (A) is a schematic end view for explaining a connection portion between the connection waveguide portion and the first input / output portion, and (B) is a connection portion between the connection waveguide portion and the first input / output portion. It is a schematic plan view for demonstrating. (A) is a schematic plan view for demonstrating the connection part of a connection waveguide part and a 1st input / output part, (B) is the structure shown to (A) cut out by the II-II line | wire It is a schematic end view. It is a schematic plan view which shows the 3rd laser radar of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the shape, size, and arrangement relationship of each component are merely schematically shown to the extent that the present invention can be understood. In the following, a preferred configuration example of the present invention will be described. However, the material and numerical conditions of each component are merely preferred examples. Therefore, the present invention is not limited to the following embodiments, and many changes or modifications that can achieve the effects of the present invention can be made without departing from the scope of the configuration of the present invention.

(Optical waveguide element)
With reference to FIG. 1, an optical waveguide device (hereinafter also simply referred to as an optical waveguide device) according to a first embodiment of the present invention will be described. FIG. 1A is a schematic plan view showing an optical waveguide element. Note that in FIG. 1A, a support substrate, a clad, and an electrode to be described later are omitted. FIG. 1B is a schematic end view of the structure shown in FIG. 1A taken along line II.

  In the following description, for each component, the direction along the light propagation direction is the length direction. The direction along the thickness of the support substrate is the thickness direction. Moreover, let the direction orthogonal to a length direction and a thickness direction be a width direction.

  The optical waveguide device 100 includes a support substrate 10, a clad 20, an optical waveguide core 30, and an electrode 40. The optical waveguide core 30 includes a first input / output unit 31, a second input / output unit 35, and a plurality of thin wire waveguides 33-1 that connect the first input / output unit 31 and the second input / output unit 35 in parallel. To n (n is a positive integer), and refractive index control units 34-1 to n provided in the middle of the thin wire waveguides 33-1 to 33-n. The first input / output unit 31, the arrayed waveguide unit 32, and the second input / output unit 35 are formed along a common reference plane S. Here, the reference plane S can be a plane parallel to the upper surface of the support substrate 10, for example.

  The optical waveguide device 100 is used, for example, as a transmitter or receiver of a laser radar. Here, as an example, a configuration example in which the optical waveguide device 100 is used as a transmission unit will be described. In this case, the optical waveguide element 100 is connected to a light emitting element such as a pulsed light source (hereinafter also referred to as a pulsed light source) at a position deviating from the reference plane S in the first input / output unit 31.

  In the optical waveguide device 100, light from the pulse light source is input to the first input / output unit 31. The light input to the first input / output unit 31 is branched into n and sent to the thin wire waveguides 33-1 to 33-n of the arrayed waveguide unit 32. The light propagating through each of the thin wire waveguides 33-1 to 33-n is given a phase shift with a different amount of shift (that is, the phase is controlled) in the refractive index control units 34-1 to 34-n. The phase-controlled light that propagates through each of the thin wire waveguides 33-1 to 33-n is combined at the second input / output unit 35 and output as irradiation light.

  The support substrate 10 is composed of a flat plate made of, for example, single crystal Si.

The clad 20 is formed on the support substrate 10 so as to cover the upper surface of the support substrate 10 and include the optical waveguide core 30. The clad 20 is formed using, for example, SiO ₂ as a material.

  The optical waveguide core 30 is made of Si having a higher refractive index than that of the cladding 20. As a result, the optical waveguide core 30 functions as a light transmission path, and light input to the optical waveguide core 30 propagates in a propagation direction corresponding to the planar shape of the optical waveguide core 30.

  In order to prevent the propagating light from escaping to the support substrate 10, the optical waveguide core 30 is preferably formed to be separated from the support substrate 10 by at least 3 μm, for example.

  The first input / output unit 31 is configured as a grating coupler. The first input / output unit 31 will be described with reference to FIG. FIG. 2A is a schematic end view for explaining the first input / output unit 31, and shows an end surface obtained by cutting the first input / output unit 31 along the length direction.

  A grating is formed in the first input / output unit 31. The grating is formed by forming a lattice groove 51 in the first input / output unit 31. The lattice groove 51 is formed by being drilled from the upper surface of the first input / output part 31 to the middle in the thickness direction. A plurality of lattice grooves 51 are periodically formed along the length direction. The grating diffracts light (that is, light propagating in a direction crossing the reference plane S) input from a pulse light source located at a position away from the reference plane S, and couples it with light propagating in the direction along the reference plane S. Let

  As another configuration example of the first input / output unit 31, as shown in FIG. 2B, a grating is formed at the end of each of the thin wire waveguides 33-1 to 33-n, so that the first input as a grating coupler is formed. The output unit 31 can also be configured. FIG. 2B is a schematic plan view showing a configuration example when the first input / output unit 31 as a grating coupler is formed at the end of each of the thin wire waveguides 33-1 to 33-n. In FIG. 2B, the support substrate and the clad are omitted.

  The grating is formed by forming lattice grooves 52a and 52b at the end portions of the thin wire waveguides 33-1 to 33-n. A plurality of grating grooves 52a are periodically formed along the length direction on one side surface of the thin wire waveguides 33-1 to 33-n. A plurality of grating grooves 52b are periodically formed on the other side surface of the thin wire waveguides 33-1 to 33-n at the same period as the grating grooves 52a along the length direction.

  Furthermore, as another configuration example of the grating formed in the first input / output unit 31, a photonic crystal can be used as shown in FIG. FIG. 2C is a schematic plan view illustrating a configuration example when a photonic crystal is formed as the first input / output unit 31. In FIG. 2C, the support substrate and the clad are omitted.

  The photonic crystal is configured by forming holes 53 in the first input / output unit 31. The hole 53 is formed so as to penetrate the first input / output unit 31 from the upper surface to the lower surface. The holes 53 are formed in a plurality of rows. A plurality of holes 53 are periodically formed along the length direction in each row.

  Each of the thin wire waveguides 33-1 to 3 to n included in the arrayed waveguide portion 32 is formed by combining a curved waveguide and a straight waveguide. The thin wire waveguides 33-1 to 33-n can have a thickness and a width as small as about several hundred nm, for example.

  Tapered portions 36-1 to 36 -n are provided between the thin wire waveguides 33-1 to 3 -n and the first input / output unit 31. The taper portions 36-1 to 36-n are tapered so that the width continuously decreases from one end connected to the first input / output unit 31 to the other end connected to the thin wire waveguides 33-1 to 33-n. Yes. The widths of the other ends of the taper portions 36-1 to 36-n connected to the thin wire waveguides 33-1 to 33-n are designed to coincide with the widths of the thin wire waveguides 33-1 to 33-n. By providing the taper portions 36-1 to 36-n, reflection of light propagating between the first input / output unit 31 and the thin wire waveguides 33-1 to 33-n can be reduced. When the grating coupler according to FIG. 2B is used as the first input / output unit 31, the tapered portions 36-1 to 36-n can be omitted.

  The refractive index controllers 34-1 to 3-4-n are set as regions immediately below the electrodes 40 to be described later in the middle of the thin-line waveguides 33-1 to 3-n. In the refractive index control units 34-1 to 34-n, the phase shifts of different amounts of shift are given to the light propagating through the thin wire waveguides 33-1 to 33-n by the action of the electrodes 40.

  The second input / output unit 35 is configured as a grating coupler. A grating is formed in the second input / output unit 35 as in the first input / output unit 31. The grating diffracts the light propagating in the direction along the reference plane S and combines it with the light propagating in the direction intersecting the reference plane S. As a result, the second input / output unit 35 outputs the light transmitted from the arrayed waveguide unit 32 in the direction away from the reference plane S as irradiation light. The traveling direction of the irradiation light in the width direction (shown as the x direction in FIG. 1A) depends on the phase shift given by the refractive index control units 34-1 to 3-4 of the thin wire waveguides 33-1 to 33-n. Determined. Therefore, in each of the refractive index control units 34-1 to 34-n, irradiation light for scanning in the x direction can be output by controlling the phase shift of the light.

  Tapered portions 37-1 to 37 -n are provided between the second input / output unit 35 and the thin wire waveguides 33-1 to 33 -n. The tapered portions 37-1 to 37-n are tapered so that the width continuously increases from one end connected to the thin wire waveguides 33-1 to 33-n to the other end connected to the second input / output unit 35. Yes. The widths of the ends of the taper portions 37-1 to 37-n connected to the thin wire waveguides 33-1 to 33-n are designed to coincide with the widths of the thin wire waveguides 33-1 to 33-n. By providing the taper portions 37-1 to 37-n, reflection of light propagating between the thin wire waveguides 33-1 to 33-n and the second input / output unit 35 can be reduced.

  The electrodes 40-1 to 40-n are formed at positions that cover the refractive index control units 34-1 to 3-n via the clad 20. Joule heat can be generated by passing a current through the electrodes 40-1 to 40-n. The refractive index of the refractive index control units 34-1 to 34-1 can be changed by the thermo-optic effect due to the heat generation. As a result, the phase of light propagating through the refractive index control units 34-1 to 34-1 can be shifted.

  In the optical waveguide device 100 described above, the light from the pulse light source is input to the thin wire waveguides 33-1 to 33-n via the first input / output unit 31 configured as a grating coupler. And according to the intensity | strength of the light from a pulse light source, and the tolerance of the thin wire | line waveguides 33-1 to 3-n, the installation number of the thin wire | line waveguides 33-1 to 3-n is determined, and light is branched. Therefore, unlike the case where the light from the pulse light source is directly input to the small-sized waveguides 33-1 to 33-n, the optical waveguide device 100 can suppress the two-photon absorption. Therefore, the optical waveguide element 100 has high resistance to high-intensity light, and can prevent the problem of deterioration of the optical waveguide even when it is used, for example, in a laser radar transmitter.

  Here, the light from the pulse light source has an intensity of several to several tens of watts, whereas the resistance to the light intensity of the Si waveguide is limited to about 200 mW. For this reason, it is preferable to form 20 or more fine wire waveguides 33-1 to 33-n. The output angle of the irradiation light output from the second input / output unit 35 with respect to the reference plane S is λ / D, where D is the separation distance between adjacent thin wire waveguides 33-1 to 33-n, and λ is the wavelength. It will be about. Therefore, the output angle (the angle between the reference plane S and the output light along the x direction) can be increased by designing the separation distance D between the thin wire waveguides 33-1 to 33-n to be small. Here, the separation distance D between the thin wire waveguides 33-1 to 33-n can be set to several μm.

(First laser radar)
A laser radar (hereinafter also referred to as a first laser radar) according to a second embodiment of the present invention will be described with reference to FIGS. Here, a configuration when the above-described optical waveguide device 100 is used as a transmission unit of a laser radar will be described. 3 and 4 show only the transmission unit of the first laser radar. FIG. 3 is a schematic plan view showing the first laser radar. In FIG. 3, the cladding and the electrodes are omitted. FIG. 4 is a schematic side view of the structure shown in FIG. 3 as viewed from the left side of the drawing. In FIG. 4, only the support substrate, the second input / output unit of the optical waveguide element, and a lens described later are shown, and other components are omitted. Since the first laser radar is configured to include the above-described optical waveguide device 100 (see FIG. 1), common components of the optical waveguide device 100 are denoted by the same reference numerals, and description thereof is omitted. .

  The first laser radar 200 includes a plurality of optical waveguide elements 100, a plurality of pulse light sources 110 connected to the respective optical waveguide elements 100 in a one-to-one correspondence, and a lens 120 as a transmission unit. FIG. 3 shows a configuration example in which the first laser radar 200 includes four optical waveguide elements 100-1 to 100-4 and four pulse light sources 110-1 to 110-4 corresponding thereto.

  Each optical waveguide core 30 of the optical waveguide elements 100-1 to 100-4 is formed on a common support substrate 10 along a common reference plane S (see FIG. 1B). Each optical waveguide core 30 is formed so as to be included in a common clad 20 (see FIG. 1B).

  The optical waveguide elements 100-1 to 100-4 are provided in the same direction in the scanning direction (x direction) of irradiation light by phase control using the above-described refractive index control units 34-1 to 3-4-n. Furthermore, the optical waveguide elements 100-1 to 100-4 are arranged such that the respective second input / output units 35 are arranged along a direction (y direction) orthogonal to the x direction. 3 shows an example in which the second input / output units 35 are arranged in a straight line along the y direction, the arrangement of the optical waveguide elements 100-1 to 100-4 is not limited to this. The optical waveguide elements 100-1 to 100-4 may be arranged as long as the second input / output unit 35 is arranged along the y direction so as to perform scanning in the y direction by the irradiation light from each second input / output unit 35. . For example, the optical waveguide elements 100-1 to 100-4 can be arranged so that the second input / output units 35 are arranged in a staggered pattern in two rows along the y direction.

  The pulse light sources 110-1 to 110-4 generate pulsed light, and input the generated pulsed light to the first input / output units 31 of the corresponding optical waveguide elements 100-1 to 100-4, respectively. The pulse light sources 110-1 to 110-4 are provided at positions that deviate from the reference plane S (see FIG. 1B). Therefore, the light from the pulse light source propagates in the direction intersecting the reference plane S.

  The lens 120 is provided to face the upper surface of the support substrate 10 at a position that spatially overlaps the second input / output units 35 of the optical waveguide elements 100-1 to 100-4. Irradiation light output from each second input / output unit 35 is input to the lens 120 and is output in a direction corresponding to the curvature of the lens 120.

  Depending on the arrangement of the second input / output units 35 in the y direction of the optical waveguide elements 100-1 to 100-4, the irradiation light from each second input / output unit 35 has a different input position to the lens 120. For this reason, the irradiation light from each 2nd input / output part 35 passes through the lens 120, respectively, and the output direction of ay direction differs. Therefore, in the first laser radar 200, by providing a plurality of optical waveguide elements 100 and disposing the second input / output units 35 along the y direction, scanning in the y direction with irradiation light becomes possible. Further, as described above, the scanning in the x direction by the irradiation light is possible by the phase control using the refractive index control units 34-1 to 34-n.

  When the target is detected using the first laser radar 200, one of the pulse light sources 110-1 to 110-4 is selected and driven. Then, the phase of the pulsed light from the selected pulsed light sources 110-1 to 110-4 is controlled in the corresponding optical waveguide elements 100-1 to 100-4 using the refractive index control units 34-1 to 34-n. Are output as irradiation light for scanning in the x direction. By performing this operation by sequentially driving the pulse light sources 110-1 to 110-4, it is possible to scan in the x direction at each position in the y direction while scanning the object in the y direction. As described above, the first laser radar 200 can irradiate the object by sweeping the irradiation light in the x direction and the y direction.

  Further, in the first laser radar 200, reflected light from an object is received by a receiving unit (not shown) formed in a region different from the transmitting unit of the support substrate 10. In the first laser radar 200, since the irradiation light is sequentially output from each of the optical waveguide elements 100-1 to 100-4, the reflected light from each position in the y direction of the object is sequentially received at different times. Is done.

  Therefore, the reflected light from which position in the y direction of the object can be identified based on the received time. Then, by combining the reflected light received at each time, it is possible to detect the size, shape, distance from the object, and the like.

(Second laser radar)
A laser radar according to a third embodiment of the present invention (hereinafter also referred to as a second laser radar) will be described with reference to FIGS. Here, a configuration when the above-described optical waveguide device 100 is used as a transmission unit of a laser radar will be described. Therefore, FIGS. 5 and 6 show only the transmitter of the second laser radar. FIG. 5 is a schematic plan view showing the second laser radar. In FIG. 5, the cladding and the electrodes are omitted. FIG. 6A is a schematic side view of the structure shown in FIG. 5 viewed from the left side of the drawing. FIG. 6B is a schematic side view of the structure shown in FIG. 5 viewed from the lower side of the drawing. In FIG. 6, only the support substrate, the second input / output unit of the optical waveguide element, the lens, and a light shielding plate described later are shown, and other components are omitted. Since the second laser radar is configured to include the above-described optical waveguide device 100 (see FIG. 1), common components of the optical waveguide device 100 are denoted by the same reference numerals, and description thereof is omitted. . Also, the same reference numerals are given to the components common to the first laser radar 200 described above, and the description thereof is omitted.

  The second laser radar 300 includes a plurality of optical waveguide elements 100, one pulse light source 110, a connection waveguide unit 130, a lens 120, and a light shielding plate 140 as a transmission unit. FIG. 5 shows a configuration example in which the second laser radar 300 includes four optical waveguide elements 100-1 to 100-4.

  The connection waveguide section 130 is formed on the support substrate 10 common to the optical waveguide cores 30 of the optical waveguide elements 100-1 to 100-4. Further, the connection waveguide section 130 is formed so as to be included in the clad 20 common to each optical waveguide core 30.

The connection waveguide section 130 has a refractive index higher than that of the clad 20 and a refractive index lower than that of the optical waveguide core 30. For example, the connection waveguide section 130 is made of SiO _x (x is a positive integer) or SiN. . As a result, the connection waveguide section 130 functions as a light transmission path, and light input to the connection waveguide section 130 propagates in a propagation direction according to the planar shape of the connection waveguide section 130. Further, since the refractive index is lower than that of the optical waveguide core 30, the thickness and width of the connection waveguide portion 130 are designed to be 1 μm or larger and larger than the optical waveguide core 30.

  The connection waveguide part 130 connects between the pulse light source 110 and the first input / output part 31 of each of the optical waveguide elements 100-1 to 100-4. Therefore, the light from the pulse light source 110 is distributed to the first input / output units 31 of the respective optical waveguide devices 100-1 to 4 through the connection waveguide unit 130.

  As described above, since the connection waveguide section 130 is larger than the optical waveguide core 30, the influence of two-photon absorption is small. Therefore, the pulse light source 110 and the connection waveguide section 130 can be directly connected by end face coupling or the like without using an input / output section having a light distribution mechanism such as a grating coupler.

  An end portion of the connection waveguide unit 130 connected to the first input / output unit 31 includes the first input / output unit 31. With reference to FIG. 7, the connection between the connection waveguide unit 130 and the first input / output unit 31 will be described. FIG. 7A is a schematic end view for explaining a connection portion between the connection waveguide section 130 and the first input / output section 31. The connection waveguide section 130 and the first input / output section 31 are long. The end surface cut out along the direction is shown.

  The first input / output unit 31 is included at the end of the connection waveguide unit 130. As described above, by including the first input / output unit 31 in the connection waveguide unit 130, the light that propagates through the connection waveguide unit 130 has a higher refractive index than the connection waveguide unit 130. Migrate to The light transferred to the first input / output unit 31 is diffracted by the first input / output unit 31 serving as a grating coupler, and sent to the thin wire waveguides 33-1 to 33-n.

  In the connection between the connection waveguide section 130 and the first input / output section 31, the first input / output section 31 can be replaced with a grating coupler and can be a spot size converter. The structure in this case is shown in FIG. FIG. 7B is a schematic plan view for explaining a connection portion between the connection waveguide section 130 and the first input / output section 31 when the first input / output section 31 is a spot size converter. . In FIG. 7B, the support substrate and the clad are omitted, and the connection waveguide section 130 is transparent.

  In the configuration example according to FIG. 7B, the first input / output unit 31 is configured by forming tapered portions 54-1 to n at the end portions of the thin wire waveguides 33-1 to n. The taper portions 54-1 to 54-n are tapered so that the width continuously increases from one end on the connection waveguide portion 130 side to the other end on the narrow wire waveguides 33-1 to n-side. The widths of the other ends of the taper portions 54-1 to n on the thin wire waveguides 33-1 to n are designed to coincide with the widths of the thin wire waveguides 33-1 to 33-n.

  With such a structure, light propagating through the connection waveguide section 130 gradually shifts to the taper sections 54-1 to 54-n. Since the taper portions 54-1 to 54-n have a higher refractive index than that of the connection waveguide portion 130, light that moves from the connection waveguide portion 130 to the taper portions 54-1 to 54-n has a mode field diameter (MFD: Mode Field Diameter). ) Is reduced and sent to the thin wire waveguides 33-1 to 33-n. In addition, when using the spot size converter of the structural example of FIG.7 (B) as the 1st input / output part 31, taper part 36-1 to n mentioned above can be abbreviate | omitted.

  Furthermore, as another configuration example in which the first input / output unit 31 is a spot size converter, a configuration in which the thickness of the first input / output unit 31 is changed can be employed. The configuration in this case is shown in FIG. FIG. 8A is a schematic plan view for explaining a connection portion between the connection waveguide section 130 and the first input / output section 31 when the first input / output section 31 is a spot size converter. . In FIG. 8A, the support substrate and the clad are omitted, and the connection waveguide section 130 is transparent. FIG. 8B is a schematic end view of the structure shown in FIG. 8A taken along the line II-II.

  In the configuration example according to FIG. 8, the first input / output unit 31 has a tapered shape whose thickness continuously increases from one end on the connection waveguide unit 130 side to the other end on the taper unit 36-1 to n side. Has been. The thickness of the other end of the first input / output part 31 on the taper part 36-1 to n side coincides with the thickness of the taper part 36-1 to n (that is, the thickness of the thin wire waveguides 33-1 to 33-n). Designed to be.

  With such a structure, the light propagating through the connection waveguide unit 130 gradually shifts to the first input / output unit 31. Since the first input / output unit 31 has a refractive index higher than that of the connection waveguide unit 130, the light that moves from the connection waveguide unit 130 to the first input / output unit 31 has a reduced MFD, and the tapered units 36-1 to 36-1. It is sent to the thin wire waveguides 33-1 to n through n.

  The light shielding plate 140 is a part of the optical path of light from the second input / output unit 35 to the lens 120 between each of the second input / output units 35 of the optical waveguide elements 100-1 to 100-4 and the lens 120. It is arranged at a position that intersects the optical path. Thereby, of the irradiation light from each second input / output unit 35, the irradiation light output in a direction intersecting with the light shielding plate 140 is blocked by the light shielding plate 140. Here, the light shielding plate 140 is disposed at a position that intersects the optical path of light from the second input / output unit 35 to the region on one end side along the y direction of the lens 120. Therefore, the irradiation light (base point state) at the coordinate x = 0 in the x direction is blocked by the light blocking plate 140 and does not reach the lens 120.

  When detecting an object using the second laser radar 300, the pulsed light source 110 is driven. Then, in one selected optical waveguide device 100, phase control is performed using the refractive index control units 34-1 to 34-n, so that the object is output as irradiation light for scanning in the x direction. At this time, the optical waveguide elements 100 other than the optical waveguide element 100 that performs scanning in the x direction perform phase control using the refractive index control units 34-1 to 34-n, so that the irradiation light crosses the light shielding plate 140. Output. Accordingly, only light irradiated from the optical waveguide element 100 that performs scanning in the x direction is output through the lens 120 at a certain time, and light irradiated from other optical waveguide elements 100 is blocked by the light shielding plate 140. Then, by sequentially selecting the optical waveguide elements 100-1 to 100-4 and scanning in the x direction, it is possible to scan in the x direction at each position in the y direction while scanning the object in the y direction. it can. Thus, the second laser radar 300 can irradiate the object by sweeping the irradiation light in the x direction and the y direction without providing the plurality of pulse light sources 110. Therefore, the second laser radar 300 is advantageous from the viewpoint of power saving. In addition, since the pulse light source 110 is generally expensive, the second laser radar 300 that does not require a plurality of pulse light sources 110 is advantageous in terms of cost.

(Third laser radar)
A laser radar (hereinafter also referred to as a third laser radar) according to a fourth embodiment of the present invention will be described with reference to FIG. Here, a configuration when the above-described optical waveguide device 100 is used as a transmission unit of a laser radar will be described. FIG. 9 shows only the transmission unit of the third laser radar. FIG. 9 is a schematic plan view showing a third laser radar. In FIG. 9, the cladding and the electrodes are omitted. Since the third laser radar is configured to include the above-described optical waveguide element 100 (see FIG. 1), the common constituent elements of the optical waveguide element 100 are denoted by the same reference numerals, and description thereof is omitted. . Also,
The third laser radar is different from the above-described second laser radar in that the light shielding plate is omitted and a delay line is added. Since other components are the same as those of the second laser radar, common components are denoted by the same reference numerals, and description thereof is omitted.

  In the third laser radar 400, the delay line 150 is provided in the middle of the connection waveguide section 130. The delay line 150 is formed integrally with the connection waveguide section 130 as a part of the connection waveguide section 130. Here, a delay line 150-1 is connected to the first input / output unit 31 of the optical waveguide device 100-1 and the pulse light source 110 in the connection waveguide unit 130. A delay line 150-2 is provided at a portion connecting the output unit 31 and the pulse light source 110, and a delay line 150-3 is provided at a portion connecting the first input / output unit 31 and the pulse light source 110 of the optical waveguide device 100-3. , Each provided. In the third laser radar 400, by providing these delay lines 150-1 to 150-3, the light transmission distances between the pulse light source 110 and the optical waveguide elements 100-1 to 100-n are set to different values. Yes.

  In the third laser radar 400, by providing the delay lines 150-1 to 150-3, the optical waveguide elements 100 having a short transmission distance from the pulse light source 110 are sequentially formed (here, in the order of the optical waveguide elements 100-4 to 1). ) The irradiation light can be output. Similarly to the first laser radar 200 and the second laser radar 300, the phase control is performed using the refractive index control units 34-1 to 34-n, so that irradiation light for scanning the object in the x direction is output. be able to. Accordingly, it is possible to scan in the x direction at each position in the y direction while scanning the object in the y direction. Thus, the third laser radar 400 can irradiate the object by sweeping the irradiation light in the x direction and the y direction without providing the plurality of pulse light sources 110. Therefore, the third laser radar 400 is advantageous from the viewpoint of power saving, like the second laser radar 300. In addition, since the pulse light source 110 is generally expensive, the third laser radar 400 that does not require a plurality of pulse light sources 110 is advantageous in terms of cost.

(Receiver)
In the first laser radar 200, the second laser radar 300, and the third laser radar 400 described above, the configuration example in which the optical waveguide element 100 is used for the transmission unit of the laser radar has been described. However, the optical waveguide device 100 can also be used for a receiving part of a laser radar.

  When the optical waveguide device 100 is used as a receiving unit of a laser radar, a light receiving device is used instead of the pulse light sources 110 of the first laser radar 200, the second laser radar 300, and the third laser radar 400 described above. Can be provided. Then, reflected light from the object is input from the second input / output unit 35. Since the light path is reversible, the reflected light input from the second input / output unit 35 is received by the light receiving element via the thin wire waveguides 33-1 to 33-n and the first input / output unit 31.

  A light receiving element using the optical waveguide element 100 can also be used as a receiving unit of the first laser radar 200, the second laser radar 300, and the third laser radar 400. In this case, for the plurality of optical waveguide elements 100 provided in the transmission unit and the reception unit, the optical waveguide element 100 that outputs irradiation light in the transmission unit and the optical waveguide element 100 that receives reflected light in the reception unit are one-to-one. Make it correspond. As described above, in the first laser radar 200, the second laser radar 300, and the third laser radar 400, the reflected light from each position in the y direction of the object is sequentially received at different times. The Therefore, the reflected light from which position in the y direction of the object can be identified based on the received time. Then, by combining the reflected light received at each time, it is possible to detect the size, shape, distance from the object, and the like.

  Here, when the configuration examples of the second laser radar 300 and the third laser radar 400 are applied to the receiving unit, one light receiving element can be provided. For this reason, for example, even if a highly sensitive but expensive light receiving element such as an avalanche photodiode (APD) is used, the cost can be suppressed.

  The reflected light from the object has a lower intensity than the light from the pulse light source 110. For this reason, when using for the receiving part of a laser radar, the 1st input / output part 31 is abbreviate | omitted from the optical waveguide element 100, and the light from each thin wire | line waveguide 33-1 to n is directly input into a light receiving element. It can also be configured.

10: support substrate 20: clad 30: optical waveguide core 31: first input / output unit 32: arrayed waveguide unit 33: fine wire waveguide 34: refractive index control unit 35: second input / output unit 40: electrode 100: optical waveguide Element 110: Pulse light source 120: Lens 130: Connection waveguide section 140: Light shielding plate 200: First laser radar 300: Second laser radar 400: Third laser radar

Claims (5)

An optical waveguide core and a clad including the optical waveguide core;
The optical waveguide core connects a first input / output unit, a second input / output unit, and the first input / output unit and the second input / output unit, which are formed along a common reference plane, in parallel. An arrayed waveguide portion including a plurality of fine wire waveguides, and a refractive index control portion provided in the middle of each of the fine wire waveguides,
The first input / output unit is a grating coupler;
Each of the refractive index control units gives a phase shift of a different shift amount to the light propagating through the thin wire waveguide,
The second input / output unit couples light propagating in a direction along the reference plane and light propagating in a direction intersecting the reference plane. An optical waveguide core and a clad including the optical waveguide core;
The optical waveguide core connects a first input / output unit, a second input / output unit, and the first input / output unit and the second input / output unit, which are formed along a common reference plane, in parallel. An arrayed waveguide portion including a plurality of fine wire waveguides, and a refractive index control portion provided in the middle of each of the fine wire waveguides,
The first input / output unit is a spot size converter;
Each of the refractive index control units gives a phase shift of a different shift amount to the light propagating through the thin wire waveguide,
The second input / output unit couples light propagating in a direction along the reference plane and light propagating in a direction intersecting the reference plane. A plurality of optical waveguide elements according to claim 1, a plurality of light emitting elements, and a lens,
The plurality of optical waveguide elements are arranged side by side along the length direction perpendicular to the width direction, with the width direction of each of the second input / output portions of the plurality of optical waveguide elements being aligned.
The plurality of light emitting elements are connected in a one-to-one correspondence with the first input / output units of the plurality of optical waveguide elements,
The laser radar, wherein the lens outputs light transmitted from each of the second input / output units of the plurality of optical waveguide elements in a direction corresponding to a curvature of the lens. A plurality of the optical waveguide device according to claim 1, one light emitting device, a connection waveguide portion, a lens, and a light shielding plate,
The plurality of optical waveguide elements are arranged side by side along the length direction perpendicular to the width direction, with the width direction of each of the second input / output portions of the plurality of optical waveguide elements being aligned.
The connection waveguide portion is formed of a material having a refractive index higher than that of the cladding and a refractive index lower than that of the optical waveguide core,
The connection waveguide portion connects between the light emitting element and each of the first input / output portions of the plurality of optical waveguide elements,
The lens outputs light transmitted from each of the second input / output units of the plurality of optical waveguide elements in a direction according to the curvature of the lens,
The light shielding plate includes a part of an optical path of light from the second input / output unit to the lens between each of the second input / output units of the plurality of optical waveguide elements and the lens. A laser radar characterized by being arranged at an intersecting position. A plurality of optical waveguide elements according to claim 1, one light emitting element, a connection waveguide section, and a lens,
The plurality of optical waveguide elements are arranged side by side along the length direction perpendicular to the width direction, with the width direction of each of the second input / output portions of the plurality of optical waveguide elements being aligned.
The connection waveguide portion is formed of a material having a refractive index higher than that of the cladding and a refractive index lower than that of the optical waveguide core,
The connection waveguide portion connects between the light emitting element and each of the first input / output portions of the plurality of optical waveguide elements,
A delay line is formed as a part of the connection waveguide part in each part of the connection waveguide part that connects the light emitting element and each of the first input / output parts. The light transmission distance between each of the first input / output unit and the first input / output unit is a different value.
The laser radar, wherein the lens outputs light transmitted from each of the second input / output units of the plurality of optical waveguide elements in a direction corresponding to a curvature of the lens.

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