KR102475891B1 - Edge light emitting laser source, apparatus for obtaining 3D image having the same - Google Patents

Abstract

A side emitting laser light source and a 3D image capture device including the same are disclosed.
In the disclosed side-emitting laser light source, an active layer may be provided on a substrate, and a wavelength selection section including a plurality of grating regions oscillating light in a plurality of wavelength bands may be provided in the active layer.

Description

Edge light emitting laser source, apparatus for obtaining 3D image having the same}

Exemplary embodiments relate to a multi-wavelength side-emitting laser light source having a single chip structure, a 3D image acquisition device including the same, and a method of manufacturing the side-emitting laser light source.

The 3D camera includes a function of measuring a distance from a plurality of points on the surface of the object to the 3D camera. Various algorithms for measuring the distance between an object and a 3D camera have been proposed, and a time-of-flight (TOF) method is generally used. The TOF method is a method of measuring a flight time from irradiating illumination light (eg, infrared rays) to an object until the illumination light reflected from the object is received by a light receiver. The flight time of the illumination light can be mainly obtained by measuring the phase delay of the illumination light, and a high-speed light modulator is used to measure the phase delay. A distance image is extracted from the time-flight of light reflected from the object and returned.

According to an exemplary embodiment, a side-emission laser light source radiating light of multiple wavelength bands with a single chip structure may be provided.

According to an exemplary embodiment, it is possible to provide a 3D image capture device including a side-emitting laser light source emitting light of multiple wavelength bands with a single chip structure.

A side emitting laser light source according to an exemplary embodiment,

Board;

an active layer provided on the substrate;

a wavelength selection section having a plurality of grating regions for selecting wavelengths of light output from the active layer; and

and a gain section configured to resonate light having multiple wavelength bands selected by the plurality of grating regions in a direction parallel to the active layer.

The plurality of grating regions may be provided in at least one of between the active layer and the gain section and between the substrate and the active layer.

The plurality of grating areas may be arranged in a direction parallel to a direction in which light is emitted from the gain section.

The plurality of grating areas may be arranged in a direction parallel to the substrate.

The plurality of grating regions may be provided outside the gain section.

The gain section may have a light exit surface and a light reflection surface, and the plurality of grating areas may be provided on at least one of a front side of the light exit surface and a rear side of the light reflection surface.

The plurality of grating areas may be arranged in a direction parallel to a direction in which light is emitted from the gain section.

The plurality of grating areas may be arranged in a direction parallel to the substrate.

The plurality of grating regions may be configured to select light of different wavelengths according to the grating array structure.

The plurality of grating areas may be provided on one same substrate.

The side-emitting laser light source may have a single chip structure.

The active layer may have a multi-quantum well structure.

The plurality of grating regions may include a material including at least one of In, Ga, As, and P.

The plurality of grating regions may include one or two or more of a dielectric material including at least one of SiO ₂ , SiN _x , TiO ₂ , MgF ₂ , Al ₂ O ₃ , and Ta ₂ O ₅ , a material including a polymer, a metal, and the like. Combinations may be included.

A wavelength selected from the plurality of grating regions may have a range of 780-1650 nm.

The substrate may include a GaAs substrate.

The side-emitting laser light source may include: a type 1 cladding layer between the substrate and the active layer; and a second-type cladding layer provided on the active layer.

A 3D image acquisition device according to an exemplary embodiment,

a side-emitting laser light source for irradiating light of multiple wavelength bands;

an optical modulator for modulating light emitted from the side-emitting laser light source and reflected from an object; and

An image sensor sensing the light modulated by the light modulator; includes,

The side-emitting laser light source has a substrate, an active layer provided on the substrate, a wavelength selection section having a plurality of grating regions for selecting a wavelength of light output from the active layer, and multiple wavelength bands selected by the plurality of grating regions. A gain section for resonating light in a direction parallel to the active layer may be included.

A side-emission laser light source according to an exemplary embodiment may reduce speckle by irradiating light having two or more wavelength bands. The side-emission laser light source according to an exemplary embodiment uses a plurality of grating array structures to have a wavelength shift characteristic corresponding to a temperature change similar to that of an optical modulator, thereby reducing deterioration in depth sensing accuracy of an object due to temperature change. .

In the method of manufacturing a side-emission laser light source according to an exemplary embodiment, a plurality of grating regions oscillating light in multiple wavelength bands may be formed on a single substrate to fabricate a multi-wavelength side-emission laser light source in a single chip structure. By manufacturing a multi-wavelength side-emitting laser light source in a single chip structure, the volume of the light source can be reduced and the manufacturing process can be simplified.

1 shows a schematic perspective view of a side-emitting laser light source according to an exemplary embodiment.
FIG. 2 is a II cross-sectional view of FIG. 1 .
FIG. 3 illustrates an example in which the side-emission laser light source shown in FIG. 1 includes grating regions of three or more wavelength bands.
4 illustrates a change in wavelength according to temperature of each of a side-emitting laser light source, an optical modulator, and a single-wavelength side-emitting laser light source according to an exemplary embodiment.
FIG. 5 shows changes in light intensity according to wavelengths of an optical modulator and a single-wavelength side-emitting laser light source at relatively high and low temperatures.
FIG. 6 shows a change in light intensity as a function of wavelength of a light modulator and a side-emission laser light source according to an exemplary embodiment for relatively high and low temperatures.
FIG. 7 illustrates a change in transmittance difference according to temperature between a side-emitting laser light source and a single-wavelength side-emitting laser light source according to an exemplary embodiment.
FIG. 8 shows the change in transmittance difference of the light modulator according to the wavelength of the single-wavelength side-emitting laser light source at 25° C., 40° C., and 50° C., respectively.
9 illustrates a change in transmittance of an optical modulator according to a wavelength of a side-emission laser light source at 25° C., 40° C., and 50° C., respectively, according to an exemplary embodiment.
FIG. 10 illustrates changes in light intensity according to a position of an object of each of a side-emitting laser light source and a single-wavelength side-emitting laser light source according to an exemplary embodiment.
11 illustrates an image formed by a side-emitting laser light source according to an exemplary embodiment.
12 shows an image formed by a single-wavelength side-emitting laser light source.
FIG. 13 illustrates an example in which the side emitting laser light source shown in FIG. 1 further includes a cladding layer.
Fig. 14 shows a schematic perspective view of a side emitting laser light source according to another exemplary embodiment.
15 is a II-II sectional view of FIG. 14;
FIG. 16 illustrates an example in which the side-emission laser light source shown in FIG. 14 includes grating regions of three or more wavelength bands.
Fig. 17 shows a schematic perspective view of a side-emitting laser light source according to another exemplary embodiment.
FIG. 18 is a III-III sectional view of FIG. 17 .
FIG. 19 illustrates an example in which the side-emitting laser light source shown in FIG. 17 includes grating regions of three or more wavelength bands.
20 schematically illustrates a 3D image acquisition device according to an exemplary embodiment.
21 schematically illustrates a 3D image capture device according to another exemplary embodiment.
22 schematically illustrates a 3D image acquisition device according to another exemplary embodiment.
23 to 26 show a method of manufacturing the side emitting laser light source shown in FIG. 1 .
27 to 31 show a method of manufacturing the side emitting laser light source shown in FIG. 14 .

Hereinafter, a side emitting laser light source according to an exemplary embodiment and a 3D image capture device including the same will be described in detail with reference to the accompanying drawings.

In the following drawings, the same reference numerals denote the same components, and the size of each component in the drawings may be exaggerated for clarity and convenience of description. The terms first, second, etc. may be used to describe various components, but these terms are only used to distinguish one component from another.

Singular expressions include plural expressions unless the context clearly dictates otherwise. Also, when a part "includes" a certain component, it means that it may further include other components unless otherwise stated.

In addition, terms such as "...unit" and "module" described in the specification mean a unit that processes at least one function or operation, which may be implemented as hardware or software or a combination of hardware and software. . Also, "A is provided to B" can be interpreted as A being provided to B in a contact or non-contact manner.

1 is a perspective view of a side emitting laser light source according to an exemplary embodiment, and FIG. 2 is a sectional view II of FIG. 1 .

The side-emission laser light source includes a substrate 10, an active layer 20 provided on the substrate 10, a wavelength selection section 30 having a plurality of grating regions 35, and a plurality of grating regions 35. It may include a gain section 40 that resonates light having a wavelength band.

The substrate 10 may be a GaAs substrate. The active layer 20 may include a material including at least one of In, Ga, As, and P, and may include, for example, a GaAs material. The active layer 20 may include a quantum well structure. For example, the active layer 20 may be composed of a single quantum well or multiple quantum wells including a compressive strained quantum well and a tensile barrier layer. The well structure may be, for example, a single or multiple quantum well structure including a GaInN quantum well and an AlGaInN barrier layer, but is not limited thereto, and the material of the active layer 20 may be variously changed according to a desired oscillation wavelength band. have.

A plurality of grating regions 35 may be provided in at least one of between the active layer 20 and the gain section 40 and between the substrate 10 and the active layer 20 .

Each of the plurality of grating areas 35 may include a different grating array structure. The plurality of grating regions 35 may select a wavelength band according to the grating array structure. Accordingly, the plurality of grating regions 35 may oscillate light in multiple wavelength bands. For example, a wavelength band may be selected by constructively interfering with light of some wavelengths and destructively interfering with light of other wavelengths according to the arrangement structure of the grating, the size of the grating, and the like. The grating arrangement structure may include, for example, an arrangement pitch of gratings, an arrangement direction of gratings, and the like. The size of the grating may include, for example, a depth of the grating, a width of the grating, and the like.

A compound containing at least one of In, Ga, Al, As, and P in the grating region 35, and at least one of SiO ₂ , SiN _x , TiO ₂ , MgF ₂ , Al ₂ O ₃ , and Ta ₂ O ₅ It may include one or a combination of two or more of materials including dielectric materials, polymers, metals, and the like. For example, the dielectric material may include SiO ₂ /SiN _x , Al ₂ O ₃ /TiO ₂ , Al ₂ O ₃ /SiN _x , SiO ₂ /Ta ₂ O ₅ , and the like.

In the side-emission laser light source according to an exemplary embodiment, the grating region 35 oscillating light in multiple wavelength bands may have an integral single-chip structure. A plurality of grating regions 35 may be provided on the same substrate 10 by having an integral single-piece chip structure without an adhesive layer for bonding or a seam that appears as a result of bonding.

The gain section 40 may resonate and amplify light having multiple selected wavelength bands. The gain section 40 may cause resonance by reciprocating light in a direction parallel to the active layer 20 .

The wavelength selection section 30 may be provided on the top or bottom of the active layer 20, on the exit surface or on the opposite side of the exit surface with respect to the light emission direction. Although FIG. 1 shows an example in which the wavelength selection section 30 is provided above the active layer 20, it is not limited thereto.

The plurality of grating areas 35 may include, for example, a first grating area 35-1 and a second grating area 35-2. However, the number of grating regions is not limited thereto and may be provided in various ways. The first and second grating regions 35-1 and 35-2 may serve as distributed feedback, for example. For example, the first grating region 35-1 may selectively reflect light of the first wavelength band λ1 and the second grating region 35-2 may selectively reflect light of the second wavelength band λ2. have.

A resonance space in which light of a wavelength band selected from the multi-wavelength side-emitting laser light source shown in FIGS. 1 and 2 resonates may be referred to as, for example, a laser cavity. The width LC of the laser cavity may be, for example, 1 mm or less. However, it is not limited thereto, and the width of the laser cavity may be designed in various ways.

FIG. 3 illustrates an example in which the plurality of grating regions 35 of the side-emitting laser light source shown in FIG. 1 oscillates light of two or more different wavelength bands.

The plurality of grating areas 35 include a first grating area 35-1, a second grating area 35-2, a third grating area 35-3, ... nth grating area 35-n. can include The first to nth grating regions 35-1, 35-2, 35-3, ... 35-n may select light of different wavelength bands, or some of the grating regions may select the same wavelength band. of light may be configured to be selected. The first to n-th grating regions 35-1, 35-2, 35-3, ... 35-n may be arranged in parallel with respect to the light emission direction. In the first to n-th grating regions 35-1, 35-2, 35-3, ... 35-n, a wavelength band may be selected according to the arrangement period of the grating, the size of the grating, and the like.

For example, referring to FIG. 2 , each grating area may include alternately arranged lands L and grooves G. An arrangement period of the grating may be, for example, a pitch Pi between neighboring lands L (or grooves G). And, the size of the grating may be changed by, for example, the height, width and/or length of the land L (or groove G). An emission direction of light from each grating area may be in a direction parallel to the grating arrangement direction. In other words, the emission direction of the light may be the side direction of the side-emitting laser light source.

For example, the first grating region 35-1 selects light of a first wavelength λ1, the second grating region 35-2 selects light of a second wavelength λ2, and the nth wavelength λ2. The grating area 35-n may select and reflect light of the nth wavelength λn.

The light of the wavelength band selected in each grating region may resonate while reciprocating in the gain section 40 . Reflective regions may be provided on both sides of the gain section.

A side-emission laser light source according to an exemplary embodiment may have an integral single-chip structure in which a plurality of grating regions configured to emit light of a plurality of wavelengths are arranged in an array structure. The single-chip structure is a structure that does not have an adhesive layer for bonding or a seam resulting from bonding, and may represent a structure in which a side-emitting laser light source is fabricated on a single substrate.

A side-emission laser light source according to an exemplary embodiment may be used, for example, to obtain a 3D image. In order to obtain a 3D image, distance (or depth) information on a subject is required, and an optical modulator having excellent electro-optical response characteristics may be used to obtain a 3D image with high distance (or depth) accuracy. However, when the difference between the characteristics of the light source and the light modulator due to temperature changes is large, distance (or depth) accuracy may be degraded. Hereinafter, a change in the characteristics of the light source and the light modulator according to temperature change will be described.

4 shows wavelength change characteristics according to temperature. The horizontal axis of the graph represents the temperature, and the vertical axis represents the wavelength, to show only the tendency of change characteristics, and units are omitted. A single-wavelength side-emitting laser light source exhibits a wavelength change characteristic of approximately 0.3 nm/°C with temperature change. The optical modulator exhibits a wavelength change characteristic of approximately 0.1 nm/° C. with temperature change. The multi-wavelength side-emitting laser light source according to this embodiment exhibits a wavelength change characteristic of 0.07 nm/°C. According to this result, the single-wavelength side-emitting laser light source may have a difference in wavelength change characteristics with the light modulator of about 0.2 nm/°C according to temperature. In contrast, the multi-wavelength side-emitting laser light source according to the present embodiment may have a difference in wavelength change characteristics with an optical modulator of about 0.03 nm/°C according to temperature. Therefore, the multi-wavelength side-emitting laser light source according to the present embodiment has a temperature characteristic relatively similar to that of an optical modulator compared to a single-wavelength laser, and thus can have high distance (or depth) accuracy for temperature changes in the surrounding environment. .

5 shows a comparison between the light intensity according to the wavelength of a single-wavelength side-emitting laser light source and the light intensity according to the wavelength of the light modulator. The light intensity is shown for a relatively high temperature (HT) and a relatively low temperature (LT), and temperature change characteristics with the light modulator are compared. The solid line is for a single wavelength side-emitting laser light source, and the dotted line is for the light modulator. A wavelength difference between a first peak point PL1 at a low temperature LT and a second peak point PL2 at a high temperature HT of a single-wavelength side-emitting laser light source is referred to as Δλ1. A wavelength difference between the third peak point PM1 at the low temperature LT and the fourth peak point PM2 at the high temperature HT of the light modulator is referred to as Δλ2.

6 shows a comparison between the light intensity according to the wavelength of the multi-wavelength side-emitting laser light source and the light intensity according to the wavelength of the light modulator according to the present embodiment. The light intensity is shown for a relatively high temperature (HT) and a relatively low temperature (LT), and temperature change characteristics with the light modulator are compared. The solid line is for the multi-wavelength side-emitting laser light source according to this embodiment, and the dotted line is for the light modulator. The wavelength difference between the fifth peak point PE1 at the low temperature LT and the sixth peak point PE2 at the high temperature HT of the multi-wavelength side-emitting laser light source according to the present embodiment is referred to as Δ?3. do. As described above, the wavelength difference between the third peak point PM1 at the low temperature LT and the fourth peak point PM2 at the high temperature HT of the light modulator is Δλ2. Comparing FIGS. 5 and 6 , Δλ1>Δλ2, and Δλ2 and Δλ3 may be almost the same. That is, the side-emitting laser light source according to the present embodiment may have characteristics substantially similar to the change in light intensity characteristics according to the wavelength of the light modulator.

A side-emission laser light source according to an exemplary embodiment may have characteristics corresponding to the wavelength change characteristics of the light modulator and the light intensity change characteristics with respect to temperature change. That is, the difference between the wavelength change of the light modulator and the wavelength change of the light source according to the temperature change can be reduced. Therefore, it is possible to efficiently compensate for a change in the characteristics of the light modulator due to a change in temperature, and it is possible to increase the accuracy of the 3D distance sensor.

7 shows a transmittance difference of an optical modulator according to temperature. The difference in transmittance represents a difference in transmittance when voltage is applied to the light modulator and transmittance when voltage is not applied. Transmittance when voltage is not applied to the optical modulator may be higher than transmittance when voltage is applied. The greater the transmittance difference, the higher the accuracy of the 3D distance sensor. Here, the temperature may represent the ambient temperature of the light modulator. The dotted line represents a single-wavelength side-emitting laser light source, and the solid line represents a multi-wavelength side-emitting laser light source according to the present embodiment. For a single-wavelength side-emitting laser light source, the difference in transmittance of the light modulator changes with temperature change, whereas for the multi-wavelength side-emitting laser light source according to the present embodiment, the difference in transmittance of the light modulator is almost uniform regardless of temperature change. can When the transmittance difference of the light modulator is kept constant regardless of the temperature, the accuracy of the 3D distance sensor can be kept constant without being affected by the temperature change. When the transmittance difference of the light modulator changes according to the temperature change, the light modulator reacts sensitively to the temperature, and thus the accuracy of distance sensing may deteriorate.

Meanwhile, the side-emitting laser light source according to an exemplary embodiment may emit light in a red wavelength band. For example, the side-emitting laser light source may emit light having a wavelength ranging from 780 nm to 1650 nm. The side-emitting laser light source may emit light having a wavelength ranging from 800 nm to 1600 nm, for example.

8 shows a change in maximum transmittance difference of an optical modulator according to a wavelength of a single wavelength side-emitting laser light source for each temperature. 8 shows a change in the maximum transmittance difference of the light modulator according to the wavelength of light when the external temperature of the light modulator is 25° C., 40° C., and 50° C. Since heat is generated in the optical modulator, the temperature of the optical modulator is generally higher than the external temperature. 8 shows a case where the temperature of the light modulator is 50°C, 60°C, and 70°C, respectively, for external temperatures of 25°C, 40°C, and 50°C. The optical modulator may ensure good sensing efficiency of the 3D distance sensor when the maximum transmittance difference is about 30% or more. Referring to FIG. 8 , it can be seen that the overlapping wavelength band in which the optical modulator can secure a transmittance difference of approximately 30% regardless of the external temperature is 3.5 nm. FIG. 9 shows the change in the maximum transmittance difference of the light modulator according to the wavelength of the multi-wavelength side-emitting laser light source according to the present embodiment according to temperature. Referring to FIG. 9 , an overlapping wavelength band corresponding to a transmittance difference of approximately 30% at external temperatures of 25° C., 40° C., and 50° C. may be 7 nm. With respect to the possible external temperature range of the light modulator, the larger the overlapping wavelength band that can secure the predetermined transmittance difference, the smaller the difference in light transmission characteristics according to the temperature change between the light source and the light modulator, and the difference in light transmission characteristics according to the temperature change The smaller the number, the higher the accuracy of distance sensing.

10 illustrates a fluctuation pattern of a single-wavelength side-emitting laser light source and a multi-wavelength side-emitting laser light source for illumination positions. For example, FIG. 11 shows an image obtained by capturing an object OBJ using light emitted from a single-wavelength side-emitting laser light source, and FIG. 12 shows an image obtained by using light emitted from a multi-wavelength side-emitting laser light source. This shows an image of the object (OBJ) photographed. 10 shows the measured light intensity at a predetermined position (P) of the image of the object (OBJ) and expressed in arbitrary units (a.u.). In FIG. 10 , a dotted line indicates a single-wavelength side-emitting laser light source, and a solid line indicates a multi-wavelength side-emitting laser light source. For example, the maximum amplitude of a fluctuation pattern of a single-wavelength side-emitting laser light source may be 18, and the maximum amplitude of a fluctuation pattern of a multi-wavelength side-emitting laser light source may be 11. In this way, the fluctuation amplitude of the multi-wavelength side-emitting laser light source can be reduced compared to the single-wavelength side-emitting laser light source. The speckle of the laser can be reduced if the fluctuation amplitude is reduced.

Since the side-emission laser light source according to the exemplary embodiment is configured to have multiple wavelength bands in an integral single-chip structure, it can be miniaturized, and non-uniformity of characteristics of each wavelength band can be reduced, and production cost can be reduced.

FIG. 13 illustrates an example in which the side emitting laser light source shown in FIG. 1 further includes a cladding layer. Detailed descriptions of elements having the same reference numerals as those in FIG. 1 are omitted. For example, the first type cladding layer 21 may be provided on one surface of the active layer 20 and the second type cladding layer 22 may be provided on the other surface of the active layer 20 . The first-type cladding layer 21 may be, for example, an n-type cladding layer, and the second-type cladding layer 22 may be, for example, a p-type cladding layer. Alternatively, the first-type cladding layer 21 may be, for example, a p-type cladding layer, and the second-type cladding layer 22 may be, for example, an n-type cladding layer.

The n-type cladding layer and the p-type cladding layer may include, for example, a bulk crystal of GaN, AlGaN, or AlGaInN, or a superlattice structure of AlGaN/AlGaN or AlGaN/GaN. However, it is not limited thereto and may be formed of various materials. The first-type cladding layer 21 and the second-type cladding layer 22 can enhance optical efficiency by improving optical confinement.

14 is a perspective view of a side emitting laser light source according to another exemplary embodiment, and FIG. 15 is a cross-sectional view II-II of FIG. 14 . The side-emission laser light source includes a substrate 110, an active layer 120 provided on the substrate 110, a wavelength selection section 130 having a plurality of grating regions 135, and multiple layers selected by a plurality of grating regions 135. It may include a gain section 140 that resonates light having a wavelength band. The wavelength selection section 130 may be provided parallel to the side of the active layer 120 . That is, the active layer 120 may be provided on a portion of the substrate 110 and the wavelength selection section 130 may be provided on the remaining portion of the substrate 110 . A gain section 140 may be provided above the active layer 120 .

A plurality of grating regions 135 may be provided outside the gain section 140 . For example, the gain section 140 may have a light exit surface and a light reflection surface, and a plurality of grating regions 135 may be provided on at least one of a front side of the light exit surface and a rear side of the light reflection surface.

The plurality of grating areas 135 may include, for example, a first grating area 135-1 and a second grating area 135-2. The wavelength selection section 130 may serve as, for example, a distributed Bragg reflector.

For example, a wavelength band may be selected by constructively interfering with light of some wavelengths and destructively interfering with light of other wavelengths according to the grating arrangement structure of the plurality of grating regions 135 and the size of the grating. The grating arrangement structure may include, for example, an arrangement pitch of gratings, an arrangement direction of gratings, and the like. The size of the grating may include, for example, a depth of the grating, a width of the grating, and the like. The gain section 140 may resonate and amplify light having multiple selected wavelength bands. The gain section 140 may emit amplified light while reciprocally reflecting light in a direction parallel to the active layer 120 .

In the multi-wavelength side-emitting laser light source shown in FIG. 15 , the width LC of the laser cavity may be, for example, 2 mm or less. However, it is not limited thereto, and the width of the laser cavity may be designed in various ways.

Since the DBR-type side-emission laser light source shown in FIG. 14 is configured to have multiple wavelength bands in an integrated single-chip structure, it can be miniaturized, can reduce non-uniformity of characteristics of each wavelength band, and can reduce production cost. . In addition, since the difference in wavelength change characteristics according to the temperature change of the light modulator is relatively small compared to a single-wavelength side-emitting laser light source, efficiency and accuracy of the 3D distance sensor can be increased. In addition, the side-emitting laser light source exhibits high power and high efficiency characteristics, and has high wavelength selectivity due to the application of the grating, so that it can be effectively applied to a 3D distance sensor.

Although FIG. 14 shows an example with two grating areas, it is possible to have three or more grating areas as shown in FIG. 16, and the grating area can be designed in various ways according to a desired selected wavelength band. 16, the wavelength selection section 130 includes a first grating area 135-1, a second grating area 135-2, a third grating area 135-3, a fourth grating area 135-4, ..., may include the nth grating region 135-n. For example, the first grating region 135-1 selects light of a first wavelength λ1, the second grating region 135-2 selects light of a second wavelength λ2, and the nth wavelength λ2. The grating area 135-n may select and reflect light of an nth wavelength λn.

Next, FIG. 17 is a perspective view of a side-emitting laser light source according to an exemplary embodiment, and FIG. 18 is a cross-sectional view taken along line III-III of FIG. 17 .

An exemplary side-emitting laser light source includes a substrate 310, an active layer 320 provided on the substrate 310, a plurality of wavelength selection sections having a plurality of grating regions, and light having multiple wavelength bands selected by the plurality of grating regions. It may include a gain section 340 that resonates.

For example, a plurality of wavelength selection sections may be provided side by side on the side of the active layer 320 . For example, the first wavelength selection section 331 may be provided on one side of the active layer 320 and the second wavelength selection section 332 may be provided on the other side of the active layer 320 . A gain section 340 may be provided above the active layer 320 .

The first wavelength selection section 331 and the second wavelength selection section 332 may include a plurality of grating regions corresponding to each other. For example, the first wavelength selection section 331 includes a first grating region 335-1 configured to select a first wavelength band λ1 and a second grating region configured to select a second wavelength band λ2 ( 335-2) may be included. The second wavelength selection section 332 may include a third grating area 336-1 and a fourth grating area 336-2.

For example, the third grating area 336-1 may have the same grating array structure as the first grating area 335-1. The fourth grating area 336-2 may have the same grating array structure as the second grating area 335-2. For example, the third grating area 336-1 may have a shorter length than the first grating area 335-1. The fourth grating area 336-2 may have a shorter length than the second grating area 335-2. However, it is not limited thereto, and the length may be variously selected.

Light of the first wavelength band λ1 can be selected by the first grating area 335-1 and the third grating area 336-1, and the second grating area 335-2 and the fourth grating area Light of the second wavelength band λ2 may be selected by 336-2.

In the multi-wavelength side-emission laser light source shown in FIG. 18 , the width LC of the laser cavity may be, for example, 2.5 mm or less. However, it is not limited thereto, and the width of the laser cavity may be designed in various ways.

As shown in FIG. 19, it is also possible that each wavelength selection section includes three or more grating regions. For example, it is possible to have (335-1)(335-2)...(335-n), and the grating area can be designed in various ways according to a desired selected wavelength band.

The first wavelength selection section 331 includes the 1-1st grating area 335-1, the 1-2nd grating area 335-2, the 1-3rd grating area 335-3, and the 1-4th grating. Regions 335-4, ..., 1-n grating regions 135-n may be included. The second wavelength selection section 332 includes the 2-1st grating area 336-1, the 2-2nd grating area 336-2, the 2-3rd grating area 336-3, and the 2-4th grating. Regions 336-4, ..., may include 2-n grating regions 336-n.

For example, the 1-1st grating area 335-1 and the 2-1st grating area 336-1 select light of the first wavelength λ1, and the 1-2nd grating area 335-1 2) and the 2-2nd grating area 336-2 select light of the second wavelength λ2, and the 1-n grating area 335-n and the 2-n grating area 336-n ) may select and reflect light of the nth wavelength (λn).

Meanwhile, although not shown, a type 1 cladding layer may be provided on one surface of the active layer 320 and a type 2 cladding layer may be further provided on the other surface.

20 schematically illustrates a 3D image acquisition device 400 according to an exemplary embodiment. The 3D image capture device 400 includes a light source 410 that radiates light to an object OBJ, a light modulator 430 that modulates light reflected from the object OBJ, and light modulated by the light modulator 430. It may include an image sensor 440 that forms an image by receiving light.

As the light source 410, a multi-wavelength side-emitting laser light source described with reference to FIGS. 1 to 19 may be employed. The light source 410 may include, for example, a multi-wavelength red laser light source having an integrated single-chip structure. The red wavelength band may have, for example, a range of 780-1650 nm. The red wavelength band may have, for example, a range of 800-1600 nm. The light modulator 430 is a transmissive type and may modulate the amplitude or phase of light reflected from the object OBJ. At least one lens 420 for condensing light may be further provided between the light source 410 and the light modulator 430 .

The side-emitting laser light source 410 may radiate multi-wavelength lasers having a single chip structure to the object OBJ. In this way, a difference between a characteristic change of the light source 410 and a characteristic change of the light modulator 430 according to a temperature change may be reduced. If the difference in change in characteristics of the light source 410 and the light modulator 430 with respect to the external environment is small, the accuracy of the distance (depth) of the object OBJ may be increased. In addition, by reducing the speckle, the quality of the image obtained by the 3D image capture device may be improved.

21 shows a schematic configuration of a 3D image capture device 500 according to an exemplary embodiment.

The 3D image capture device 500 may be configured to extract depth information of the object OBJ using, for example, an optical time-of-flight method.

The 3D image acquisition device 500 includes a side-emission laser light source 505 for irradiating light of multiple wavelength bands to an object OBJ, an optical modulator 510 for modulating light reflected from the object OBJ, and an optical modulator ( It may include an image sensor 515 that senses the light modulated by 510 and converts it into an electrical signal, and a signal processing unit 530 that calculates depth image information from an output of the image sensor 515 . In addition, a controller 555 for controlling operations of the light source 505 , the light modulator 510 , the image sensor 515 , and the signal processor 530 may be included. As the light source 505, the light source described with reference to FIGS. 1 to 19 may be employed.

The 3D image capture device 500 may further include a first lens 540 that condenses the infrared light reflected from the object OBJ to the light modulator 510 . A bandpass filter 545 may be further provided between the first lens 540 and the light modulator 510 to transmit only light in a predetermined wavelength band among light reflected from the object OBJ. For example, the band pass filter 545 may transmit only light in a wavelength band irradiated from the light source 505 . The arrangement order of the first lens 540 and the band pass filter 545 may be reversed. A second lens 550 may be further provided between the light modulator 510 and the image sensor 515 to condense the light modulated by the light modulator 510 onto the image sensor 515 .

The light source 505 may be configured to emit infrared light of multiple wavelength bands, eg, in the range of 780 nm to 1650 nm. The light source 505 may be configured to emit infrared light of multiple wavelength bands, for example, in the range of 800 nm to 1600 nm.

The light source 505 may project light onto the object OBJ according to a control signal received from the controller 555 . The projection light projected from the light source 505 to the object OBJ may have a form of a periodic continuous function having a predetermined period Te. For example, the projected light may have a specially defined waveform such as a sine wave, a ramp wave, a square wave, or the like, but may also have a general undefined waveform. Also, the light source 505 may periodically project light onto the object OBJ only for a predetermined period of time by the control unit 555 .

The light modulator 510 may modulate the light reflected from the object OBJ by the control unit 555 . The light modulator 510 may modulate the size of transmitted light by changing a gain according to a light modulation signal having a predetermined waveform. To this end, the light modulator 510 may have a variable gain. The light modulator 510 may operate at a high modulation rate of, for example, tens to hundreds of MHz to identify a phase difference or a travel time of light according to a distance.

The image sensor 515 may form an image by detecting the light modulated by the light modulator 510 . For example, when only a distance to a certain point of the object OBJ is to be measured, a single optical sensor such as a photodiode or an integrator may be used as the image sensor 515 . Alternatively, when measuring distances to a plurality of points on the object OBJ at the same time, the image sensor 515 may have a one-dimensional or two-dimensional array of a plurality of photodiodes or other photodetectors. For example, the image sensor 515 may be a CCD image sensor or a CMOS image sensor having a two-dimensional array.

The signal processor 530 may calculate depth information based on the output of the image sensor 515 and generate an image including the depth information. The signal processing unit 530 may be implemented as, for example, a dedicated integrated circuit (IC) or may be implemented as software installed in the 3D image acquisition device 500 . When implemented in software, the signal processing unit 530 may be stored in a separate movable storage medium.

Light emitted from the light source 505 may be reflected from the surface of the object OBJ and may be incident to the first lens 540 . In general, an actual object (OBJ) will form a 2D array of a plurality of surfaces having different depths, that is, the distance to the imaging surface of the 3D image capture device 500, but the drawings are for simplicity of explanation. An object OBJ having first to fifth surfaces P1 to P5 having different depths is illustrated as an example. As the projected light is reflected on each of the first to fifth surfaces P1 to P5, five different time-delayed (ie, different phases) reflected lights may be generated. At this time, the reflected light reflected from the first surface P1, which is the farthest from the 3D image capture device 500, arrives at the first lens 540 after a time delay of TOF1, and the 3D image capture device ( 500) will reach the first lens 540 after a time delay of TOF5, which is smaller than TOF1.

Reflected light having different time delays (or phase delays) may be incident to the light modulator 510 . Before the light is incident to the light modulator 510 , background light or miscellaneous light outside the wavelength band irradiated from the light source 505 may be removed by the band pass filter 545 .

Amplitudes or phases of the reflected lights having different degrees of phase delay may be modulated by the optical modulator 510 . The modulated light may reach the image sensor 515 after being magnified and focused while passing through the second lens 550 . The image sensor 515 may receive the modulated light and convert it into an electrical signal. The output signals I1 to I5 of the image sensor 515 include different depth information, and the signal processing unit 530 determines the first to fifth surfaces P1 to P5 of the object OBJ based on this. ), it is possible to calculate depth information corresponding to depth (Depth1 to Depth5) and generate an image including the depth information.

22 shows a schematic configuration of a 3D image acquisition device 600 according to another exemplary embodiment.

The 3D image capture device 600 may extract depth information of the object OBJ using optical time-of-flight (TOF) along with a configuration for capturing a 2D color image.

The 3D image capture device 600 includes, for example, a light source 605 on an object OBJ, a light modulator 610 that modulates light reflected from the object OBJ, and light modulated by the light modulator 610. a first image sensor 615 that senses and converts it into an electrical signal; a second image sensor 625 that converts an optical image of the visible light (R, G, B) band reflected from the object OBJ into an electrical signal; It may include a 3D image signal processing unit 630 generating a 3D image of the object by calculating depth information and color information from electrical signals output from the first image sensor 615 and the second image sensor 625, respectively. have. In addition, a control unit 655 for controlling operations of the light source 605, the light modulator 610, the first image sensor 615, the second image sensor 625, and the 3D image signal processing unit 630 may be included. can

As the light source 605 , for example, the light source described with reference to FIGS. 1 to 19 may be employed. The light source 605 may emit infrared light (IR) of multiple wavelengths between 780 nm and 1650 nm, for example. The light source 605 may emit infrared light (IR) of multiple wavelengths between 800 nm and 1600 nm, for example.

The 3D image acquisition device 600 diverges infrared light (IR) toward the first image sensor 615 and visible light among light reflected from the object OBJ toward the second image sensor 625. A splitter 635 may be further included.

Between the beam splitter 635 and the light modulator 610, a first lens 640 condensing the infrared light (IR) diverged from the beam splitter 635 to the light modulator 610 may be further provided. A bandpass filter 645 that transmits only light in a predetermined wavelength band among light reflected from OBJ may be further provided. For example, the band pass filter 645 may transmit only light of a wavelength band irradiated from a light source. The arrangement order of the first lens 640 and the band pass filter 645 may be reversed. A second lens 650 may be further provided between the light modulator 610 and the first image sensor 615 to condense the light modulated by the light modulator 610 onto the first image sensor 615 .

In the drawing, although infrared light (IR) and visible light (R, G, and B) reflected from the object (OBJ) pass through the photographing lens 620 in common, only visible light (R, G, and B) passes through the photographing lens 620. Passing through, the infrared light (IR) may be changed into an optical arrangement that is incident on the light modulator 610 through a path that does not pass through the photographing lens 620 .

The optical modulator 610 may modulate the amplitude or phase of transmitted light by changing a gain according to an optical modulation signal having a predetermined waveform. The modulated light may be sensed by the first image sensor 615, and a signal containing depth information of the object OBJ may be output from the first image sensor 615. A signal containing color information of the object OBJ may be output from the second image sensor 625 .

The 3D image signal processing unit 630 may generate a 3D image signal from outputs of the first image sensor 615 and the second image sensor 625 .

A 3D image acquisition device according to an exemplary embodiment may acquire distance information from a robot cleaner, a motion recognition DTV (Digital TV), a Digital Security Controls (DSC) camera, a 3D camera, and an object, for example. It can be applied to various fields such as 3D cameras, motion capture sensors, and laser radars. A 3D image acquisition device may be applied to a sensor for detecting an obstacle in a robot cleaner. Also, a 3D image capture device may be employed as a depth sensor for motion recognition of a DTV. Also, the 3D image capture device may be applied to an authentication/recognition sensor of a security camera. In addition, the 3D image capture device can be applied to various 3D image capture devices through which general users can directly produce 3D content.

23 to 26 show a method of manufacturing a side-emitting laser light source according to an exemplary embodiment.

Referring to FIG. 23 , an active layer 720 may be stacked on a substrate 710 . The substrate 710 may be formed of GaAs. The active layer 720 may include a quantum well layer. Referring to FIG. 24 , a thin film layer 730 may be stacked on the active layer 720 . The thin film layer 730 may be, for example, a compound including one or a combination of two or more of In, Ga, Al, As, P, SiO ₂ , SiN _x , TiO ₂ , MgF ₂ , Al ₂ O ₃ , Ta ₂ O ₅ It may include one or a combination of two or more of materials including a dielectric material including one or a combination of two or more of, a polymer, a metal, and the like.

Referring to FIG. 25 , a grating region 735 may be formed by patterning the thin film layer 730 . The grating area 735 may include a plurality of areas having different grating array structures. A grating region having a plurality of grating array structures may be manufactured through a one-step etching process. Light of multiple wavelength bands may be selected by the plurality of grating regions 735 .

Referring to FIG. 26 , a gain section 740 may be formed in the grating area 735 .

27 to 31 illustrate a method of manufacturing a side emitting laser light source according to another embodiment.

Referring to FIG. 27 , an active layer 815 may be stacked on a substrate 810 . Referring to FIG. 28 , a partial region 823 of the active layer 815 may be etched. Referring to FIG. 29 , a thin film layer 830 may be stacked on the etched partial region 823 . Referring to FIG. 30 , a grating region 835 may be formed by patterning the thin film layer 830 . The grating area 835 may include a plurality of areas having different grating array structures. A grating region having a plurality of grating array structures may be manufactured through a one-step etching process. The grating region 835 may be formed on the same layer as the active layer 820 . Light of multiple wavelength bands may be selected by the plurality of grating regions 835 .

Referring to FIG. 31 , a gain section 840 may be formed on the active layer 820 .

In the manufacturing method of a side-emitting laser light source according to an exemplary embodiment, a plurality of grating regions oscillating light in multiple wavelength bands are formed on the same substrate to fabricate a multi-wavelength side-emitting laser light source in an integral single-chip structure. have. By manufacturing a multi-wavelength side-emitting laser light source in a single chip structure, the volume of the light source can be reduced and the manufacturing process can be simplified. Since it has a single chip structure, it is possible to reduce non-uniformity of wavelength differences between a plurality of grating areas.

In addition, the side-emission laser light source according to an exemplary embodiment reduces speckle by radiating light having two or more wavelength bands, and has a wavelength shift characteristic similar to that of an optical modulator by using a plurality of grating array structures. By doing so, it is possible to reduce the deterioration of depth sensing accuracy of the object due to temperature change.

The above embodiments are merely exemplary, and various modifications and equivalent other embodiments may be made therefrom by those skilled in the art. Therefore, the true technical scope of protection according to the embodiments of the present invention should be determined by the technical spirit of the invention described in the following claims.

10,110, 310: substrate, 20,120, 320: active layer
30, 130, 330: Wavelength selection section
35,135, 335: grating area
35-1, 135-1, 335-1: first grating area
35-2, 135-2, 335-2: Second grating area
40, 140, 340: gain section
400,500,600: 3D image acquisition device
430,510,610: light modulator
440,515,615,625: image sensor

Claims (23)

Board;
an active layer provided on the substrate;
a wavelength selection section having a plurality of grating regions for selecting wavelengths of light output from the active layer; and
A gain section for resonating light having multiple wavelength bands selected by the plurality of grating regions in a direction parallel to the active layer;
The wavelength selection section includes a first grating area configured to select light of a first wavelength and a second grating area configured to select light of a second wavelength different from the first wavelength, The side-emitting laser light source, wherein the grating regions are arranged side by side in a direction parallel to an emission direction of light in the gain section. According to claim 1,
The plurality of grating regions are provided at least one of between the active layer and the gain section and between the substrate and the active layer. delete According to claim 1,
A side-emitting laser light source in which the plurality of grating regions are arranged in a direction parallel to a substrate. According to claim 1,
The plurality of grating regions are provided on the outside of the gain section side-emitting laser light source. According to claim 5,
The gain section has a light exit surface and a light reflection surface, and the plurality of grating regions are provided on at least one of a front side of the light exit surface and a rear side of the light reflection surface. According to claim 5,
The side-emitting laser light source in which the plurality of grating regions are arranged in a direction parallel to an emission direction of light from the gain section. According to claim 7,
A side-emitting laser light source in which the plurality of grating regions are arranged in a direction parallel to a substrate. The method of any one of claims 1, 2, 4 to 8,
The side-emitting laser light source configured to select light of different wavelengths according to the grating array structure of the plurality of grating regions. The method of any one of claims 1, 2, 4 to 8,
A side-emitting laser light source in which the plurality of grating regions are provided on the same substrate. The method of any one of claims 1, 2, 4 to 8,
The side-emitting laser light source having an integral single-chip structure. The method of any one of claims 1, 2, 4 to 8,
A side-emitting laser light source in which the active layer has a multi-quantum well structure. The method of any one of claims 1, 2, 4 to 8,
The plurality of grating regions include a material containing at least one of In, Ga, As, and P. The method of any one of claims 1, 2, 4 to 8,
The plurality of grating regions may include one or a combination of two or more of a dielectric material including at least one of SiO ₂ , SiN _x , TiO ₂ , MgF ₂ , Al ₂ O ₃ , and Ta ₂ O ₅ , a material including a polymer, a metal, and the like. A side-emitting laser light source comprising a. The method of any one of claims 1, 2, 4 to 8,
The wavelength selected from the plurality of grating regions is a side-emitting laser light source having a range of 780-1650 nm. The method of any one of claims 1, 2, 4 to 8,
A side-emitting laser light source in which the substrate includes a GaAs substrate. The method of any one of claims 1, 2, 4 to 8,
a first-type cladding layer between the substrate and the active layer; and
A side emitting laser light source further comprising a second type cladding layer provided on the active layer. a side-emitting laser light source for irradiating light of multiple wavelength bands;
an optical modulator for modulating light emitted from the side-emitting laser light source and reflected from an object; and
An image sensor sensing the light modulated by the light modulator; includes,
The side-emitting laser light source has a substrate, an active layer provided on the substrate, a wavelength selection section having a plurality of grating regions for selecting a wavelength of light output from the active layer, and multiple wavelength bands selected by the plurality of grating regions. A gain section for resonating light in a direction parallel to the active layer;
The wavelength selection section includes a first grating area configured to select light of a first wavelength and a second grating area configured to select light of a second wavelength different from the first wavelength, A three-dimensional image acquisition device in which grating regions are arranged in a direction parallel to an emission direction of light in the gain section. According to claim 18,
The plurality of grating regions are provided in at least one of between the active layer and the gain section and between the substrate and the active layer. delete According to claim 18,
The plurality of grating regions are provided outside the gain section. According to claim 21,
The gain section has a light exit surface and a light reflection surface, and the plurality of grating regions are provided on at least one of a front side of the light exit surface and a rear side of the light reflection surface. The method of any one of claims 18, 19, 21 to 22,
A three-dimensional image acquisition device in which the plurality of grating regions are provided on the same substrate.

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