Optical modulator, optical beam steering device, and electronic device

Abstract

Provided is an optical modulator for amplifying intensity of incident light and modulating a phase of the incident light. The optical modulator includes a first distributed Bragg reflector (DBR) layer having a first reflectivity and including at least two first refractive index layers having different refractive indexes from each other and repeatedly alternately stacked, a second DBR layer having a second reflectivity and including at least two second refractive index layers having different refractive indexes from each other and repeatedly alternately stacked, and an active layer disposed between the first DBR layer and the second DBR layer and including a quantum well structure.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2019-0116875, filed on September 23, 2019, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The apparatus and methods according to the example embodiments relate to optical modulators, beam steering devices including optical modulators, and electronic devices including beam steering devices. Background Technology

[0004] Optical modulators, used to modulate the transmission / reflection, polarization, phase, intensity, path, etc., of incident light, are used in various optical devices. Furthermore, optical modulators with various structures have been implemented to control the light characteristics required by optical devices.

[0005] For example, liquid crystal structures with optical anisotropy and microelectromechanical systems (MEMS) utilizing micromechanical motion of light anti-reflection elements are widely used in conventional optical modulators. These optical modulators have an operating response speed of at least several μs based on their operating characteristics. Furthermore, in the optical phased array (OPA) method, the phase of light is modulated by using the interference of various pixels or by a beam of light in the form of a waveguide.

[0006] When using MEMS structures that utilize mechanical motion, the size of the optical modulator may increase, leading to higher costs. Furthermore, the application of MEMS may be limited due to issues including vibration.

[0007] According to the control technology of the OPA method, each pixel or waveguide must have a driving pixel, and the pixel arithmetic unit must have an operating driver. Therefore, the circuit and equipment may inevitably become complex and may increase the processing cost.

[0008] Recently, attempts have been made to apply metasurfaces to optical modulators. A metasurface is a structure in which values ​​smaller than the wavelength of incident light are applied to thickness, pattern, periodicity, etc. For example, optical devices with variable optical properties (e.g., refractive index) and using tunable metasurfaces based on semiconductor materials with multi-quantum-well structures have been used in a variety of technological fields, from optical communication to optical sensing.

[0009] For example, an optical modulator using a tunable metasurface may include a Fabry-Perot resonator structure formed as a sandwich structure, wherein a layer of semiconductor material is provided between a pair of distributed Bragg reflectors (hereinafter referred to as DBRs).

[0010] An optical modulator for modulating light by using a Fabry-Perot resonator structure including a pair of DBRs and a semiconductor material layer can include an optical material having a loss. In general, a large resonant structure is used for high phase modulation. However, in this case, optical loss can also increase and the efficiency of a low optical modulator is decreased. SUMMARY

[0011] Example embodiments address at least the above problems and / or disadvantages and other disadvantages not described above. Also, example embodiments are not required to overcome the above disadvantages and can not overcome any of the problems described above.

[0012] One or more example embodiments provide an optical modulator having saturated gain due to an active layer including quantum dots.

[0013] Also, one or more example embodiments provide an optical beam steering apparatus including the optical modulator having saturated gain, and an electronic device including the optical beam steering apparatus.

[0014] According to an aspect of example embodiments, there is provided an optical modulator for amplifying intensity of incident light and modulating a phase of the incident light, the optical modulator including: a first distributed Bragg reflector (DBR) layer having a first reflectivity and including at least two first refractive index layers having different refractive indexes from each other and repeatedly alternately stacked; a second DBR layer having a second reflectivity and including at least two second refractive index layers having different refractive indexes from each other and repeatedly alternately stacked; and an active layer disposed between the first DBR layer and the second DBR layer and including a quantum well structure.

[0015] The quantum well structure can include at least one quantum dot having a single gain satisfying Gs^2*Rf*Rb<1, and Gs, Rf, and Rb denote the single gain, the second reflectivity, and the first reflectivity, respectively.

[0016] The quantum well structure can include at least one quantum dot having a single gain satisfying Gs^2>1 / Rb, and Gs and Rb denote the single gain and the first reflectivity, respectively.

[0017] The quantum well structure can include a well layer and a barrier layer, and the well layer can include a plurality of quantum dots.

[0018] The active layer can include a plurality of stacked structures, and each of the plurality of stacked structures can include a well layer and a barrier layer alternately stacked.

[0019] The active layer can include a first multi-stack structure having a first plurality of stack structures and a second multi-stack structure having a second plurality of stack structures.

[0020] The optical modulator can further include a barrier layer between the first multi-stack structure and the second multi-stack structure.

[0021] The quantum well structure of the active layer can include a first multi-stack structure and a second multi-stack structure, wherein each of the first multi-stack structure and the second multi-stack structure can include a well layer and a first barrier layer alternately stacked, wherein the optical modulator can further include a second barrier layer disposed between the first multi-stack structure and the second multi-stack structure, and wherein a thickness of the second barrier layer can be greater than a thickness of the first barrier layer.

[0022] The quantum well structure of the active layer can include at least one quantum dot, and a bandgap energy of the at least one quantum dot can be equal to an energy of the incident light.

[0023] The active layer can have a saturated gain under an applied current, a value of the applied current being greater than or equal to a predetermined value.

[0024] The first reflectivity length can be greater than the second reflectivity length.

[0025] The optical modulator can further include a processor configured to individually modulate a refractive index and a gain of the active layer by applying a current between the first DBR layer and the second DBR layer.

[0026] The optical modulator can further include a plurality of superstructures disposed on the second DBR layer.

[0027] At least two of the plurality of superstructures can have different refractive indexes from each other.

[0028] The optical modulator can further include a first contact layer disposed on the first DBR layer and a second contact layer disposed on the second DBR layer.

[0029] According to an aspect of another example embodiment, there is provided an optical beam steering apparatus including: an array of optical modulators including a plurality of optical modulators including the optical modulator, the plurality of optical modulators having the same structure; and a control circuit configured to individually control refractive indexes of the plurality of optical modulators.

[0030] The plurality of optical modulators can have the same quantum dot distribution density.

[0031] The control circuit can include a plurality of complementary metal-oxide-semiconductor (CMOS) devices, each CMOS device connected to two adjacent light modulators of the plurality of light modulators.

[0032] According to an aspect of another example embodiment, there is provided an electronic device including: a light source; and a light beam steering device configured to modulate a traveling direction of light incident from the light source toward an object; a sensor configured to receive light reflected from the object; and a processor configured to analyze the light received by the sensor.

[0033] The at least one quantum dot can have a single gain satisfying 1 / Rb < Gs^2 < 1 / (Rf*Rb), and Gs, Rb, and Rf denote the single gain, the first reflectivity, and the second reflectivity, respectively.

[0034] According to an aspect of another example embodiment, there is provided an optical sensor including a light modulator, the light modulator including: a first distributed Bragg reflector (DBR) layer; a second DBR layer; and a quantum well disposed between the first DBR layer and the second DBR layer, wherein the optical sensor can be configured to apply a current between the first DBR layer and the second DBR layer to control a gain of the light modulator and a phase of incident light by band-to-band transition of electrons between a valence band and a conduction band of the quantum well. BRIEF DESCRIPTION OF DRAWINGS

[0035] Certain example embodiments will be described with reference to the accompanying drawings, in which:

[0036] Figure 1 is a lateral cross-sectional view schematically illustrating a structure of a light modulator according to an embodiment;

[0037] Figure 2 is a graph illustrating characteristics of a light modulator of Figure 1 ;

[0038] Figure 3 is a process in which a density inversion occurs in a light modulator of Figure 1 ;

[0039] Figure 4 is a process in which stimulated emission occurs in a light modulator of Figure 1 ;

[0040] Figure 5 is a process in which a refractive index is changed in a light modulator of Figure 1 ;

[0041] Figure 6is a lateral cross-sectional view schematically illustrating a structure of an optical modulator according to another embodiment;

[0042] Figure 7 is a lateral cross-sectional view schematically illustrating a structure of an optical modulator according to another embodiment;

[0043] Figure 8 is a lateral cross-sectional view schematically illustrating a structure of an optical modulator according to another embodiment;

[0044] Figure 9 is a lateral cross-sectional view schematically illustrating a structure of an optical modulator array according to an embodiment;

[0045] Figure 10 is a lateral cross-sectional view schematically illustrating a structure of a control circuit for controlling Figure 9 an optical modulator array;

[0046] Figure 11 is a lateral cross-sectional view schematically illustrating a beam steering apparatus according to an embodiment; and

[0047] Figure 12 is a block diagram illustrating a schematic structure of an electronic apparatus according to an embodiment. DETAILED DESCRIPTION

[0048] Example embodiments are described more fully hereinafter with reference to the accompanying drawings.

[0049] In the following description, like reference numerals are used to refer to like elements throughout the several drawings. It is to be understood that other specific arrangements can be utilized and that the example embodiments set forth herein are not limiting. Rather, the phraseology and terminology used herein is for the purpose of description and understanding only. Moreover, the use of "including," "comprising," "having," "containing," "carrying," "holding," "featuring," "adapting", "arranging" and the like, are not meant to be limiting.

[0050] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Expressions such as "at least one of," when preceding the

[0051] Hereinafter, an optical modulator, an optical beam steering apparatus including the optical modulator, and an electronic apparatus including the optical beam steering apparatus according to various embodiments will be described with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements, and the size or thickness of components can be exaggerated for clarity of explanation.

[0052] The terms first, second, etc. can be used herein to describe various components. However, the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from another component. The optical modulator apparatus, the optical beam steering apparatus including the optical modulator apparatus, and the electronic apparatus including the optical beam steering apparatus can be implemented in various forms and are not limited to the embodiments described herein.

[0053] Throughout the specification, it will be further understood that when a component "includes" or "comprises" an element, unless otherwise defined, the component can further include other elements, not excluding the other elements.

[0054] Figure 1 FIG. 1 is a schematic cross-sectional view illustrating a structure of an optical modulator 1100 according to an embodiment. Figure 2 FIG. 2 is a schematic cross-sectional view illustrating a structure of the optical modulator 1100 according to an embodiment. Figure 1 FIG. 3 is a graph illustrating characteristics of the optical modulator 1100 of FIG. 2.

[0055] Referring to FIG. 1, Figure 1 The optical modulator 1100 can include a first distributed Bragg reflector (DBR) layer 100 having a first reflectivity Rb, an active layer 200, and a second DBR layer 300 having a second reflectivity Rf. The first DBR layer 100 can include two refractive index layers having different refractive indexes from each other and repeatedly alternately stacked. The active layer 200 is disposed on the first DBR layer 100 and includes a quantum well structure having a stack structure in which a well layer 202 and a first barrier layer 201 are alternately stacked. At least one quantum dot 203 is disposed in the well layer 202. The second DBR layer 300 is disposed on the active layer 200 and includes two refractive index layers having different refractive indexes from each other and repeatedly alternately stacked. Further, a first contact layer 400 can be disposed on the first DBR layer 100, and a second contact layer 500 can be disposed on the second DBR layer 300. For example, the first contact layer 400 can be disposed on a lower surface of the first DBR layer 100, and the second contact layer 500 can be disposed on an upper surface of the second DBR layer 300.

[0056] The light modulator 1100 can amplify the intensity of the incident light IL. Accordingly, the output light OL can have a greater intensity than the incident light IL. Also, the light modulator 1100 can modulate the phase of the incident light IL. Accordingly, the traveling direction of the output light OL can be adjusted so that the output light OL travels in a desired direction regardless of the incident angle of the incident light IL. The functions of the light modulator 1100 to amplify the incident light IL and to modulate the phase of the incident light IL are described later with reference to the accompanying drawings.

[0057] The first DBR layer 100 and the second DBR layer 300 can form a Fabry-Perot resonator. The incident light IL incident from the outside into the second DBR layer 300 can resonate between the first DBR layer 100 and the second DBR layer 300. Herein, the first reflectivity Rb of the first DBR layer 100 can be greater than the second reflectivity Rf of the second DBR layer 300. Accordingly, light resonating between the first DBR layer 100 and the second DBR layer 300 can be output to the outside through the second DBR layer 300. Also, since the first reflectivity Rb of the first DBR layer 100 is greater than the second reflectivity Rf of the second DBR layer 300, a phase change of the incident light IL can occur within a range of 360 degrees.

[0058] The first DBR layer 100 and the second DBR layer 300 can function as a mirror having high reflectivity, and can include a pair of material layers having different refractive indices from each other. For example, the first DBR layer 100 and the second DBR layer 300 can include a structure in which low-refractive-index layers 10 having a relatively low refractive index and high-refractive-index layers 11 having a relatively high refractive index are alternately stacked. For example, the first DBR layer 100 and the second DBR layer 300 can include a structure in which AlAs / Al0.5Ga0.5As or Al0.9Ga0.1As / Al0.3Ga0.7As are repeatedly and alternately stacked. However, it is not limited thereto, and the ratio of Al to Ga can vary. In addition, the low-refractive-index layers 10 and the high-refractive-index layers 11 of the first DBR layer 100 and the second DBR layer 300 can include materials completely different from the materials described. When light of a specific wavelength is incident into the first DBR layer 100 and the second DBR layer 300 having such a structure, reflection can occur at the interface of the low-refractive-index layers 10 and the high-refractive-index layers 11. In this context, high reflectivity can be obtained by removing or reducing a phase difference between all light, so that the light has the same phase and constructive interference of the reflected light can occur. To this end, the optical thickness (a value obtained by multiplying the physical thickness of a layer by the refractive index of the layer) of each of the low-refractive-index layers 10 and the high-refractive-index layers 11 can correspond to a value of an odd multiple of λ / 4 (λ is the wavelength of incident light). As the number of times a pair of low-refractive-index layers 10 and high-refractive-index layers 11 is repeatedly stacked increases, the first DBR layer 100 and the second DBR layer 300 can have increased reflectivity. For example, the number of times a pair of low-refractive-index layers 10 and high-refractive-index layers 11 is repeatedly stacked can be greater in the case of the first DBR layer 100 than in the case of the second DBR layer 300. Accordingly, the reflectivity Rb of the first DBR layer 100 can be greater than the reflectivity of the second DBR layer 300.

[0059] The active layer 200 can include a semiconductor material having a quantum well structure. For example, the active layer 200 can include a stack structure in which the well layer 202 and the first barrier layer 201 are alternately stacked. The active layer 200 can include a plurality of the first barrier layers 201 and a plurality of the well layers 202 alternately stacked, or can include a pair of the first barrier layers 201 and one well layer 202 disposed between the pair of the first barrier layers 201. The band gap energy of the first barrier layer 201 can be greater than the band gap energy of the well layer 202. The well layer 202 has a relatively small band gap energy than the first barrier layer 201 in contact with the well layer 202, and thus, electrons and holes can have quantized energy levels in the well layer 202. For example, the first barrier layer 201 can include GaAs, and the well layer 202 can include InGaAs. However, it is not limited thereto, and the first barrier layer 201 and the well layer 202 can include other materials than the described materials. In addition, when the current source 600 applies a current between the first DBR layer and the second DBR layer so that the current flows into the active layer 200, the refractive index of the active layer 200 can be changed. Accordingly, the phase of the incident light IL and the phase of the output light OL can be different from each other. That is, as the refractive index of the active layer 200 is changed, the traveling direction of the light that has passed through the optical modulator 1100 can be changed.

[0060] The active layer 200 can further include a quantum dot. For example, at least one quantum dot 203 can be disposed in the well layer 202. However, it is not limited thereto, and a plurality of quantum dots 203 can be disposed in the well layer 202. The band gap energy of the quantum dot 203 can be less than the band gap energy of the well layer 202. The band gap energy of the quantum dot 203 can be the same as the energy of the incident light IL. For example, the quantum dot 203 can include InAs. However, it is not limited thereto, and the quantum dot 203 can include other materials than the described materials.

[0061] As described below, in the quantum dot 203, a density inversion can occur due to an applied current. When the incident light having a specific energy is incident into the quantum dot 203 in which the density inversion occurs, stimulated emission can occur. Due to the stimulated emission, the intensity of the incident light IL can be amplified. As the applied current increases, the occurrence of the stimulated emission can increase. Accordingly, the amplification rate of the intensity of the incident light IL can increase. However, when the current reaches a value equal to or greater than a specific value, the stimulated emission can not increase, and thus, the amplification rate of the intensity of the incident light IL can reach saturation. Hereinafter, the description will be made with reference to FIGS. 6A and 6B. Figure 2A saturation principle of the amplification of the intensity of the incident light IL is described. Thus, when the amplification of the intensity of the incident light IL is saturated, this can be referred to as a case where the active layer 200 has saturated gain. The saturated gain of the active layer 200 can be determined based on the distribution density of the quantum dots 203 having a single gain Gs. For example, as the distribution density of the quantum dots 203 increases, the saturated gain of the active layer 200 can increase.

[0062] The single gain Gs of the quantum dots 203 can satisfy Gs^2 * Rf * Rb < 1. When the single gain Gs is increased such that the value of Gs^2 * Rf * Rb is equal to or greater than 1, spontaneous emission can occur in the quantum dots 203. That is, when the single gain Gs of the quantum dots 203 is increased to a value exceeding a predetermined threshold, lasing can occur even when a small amount of current flows in the optical modulator 1100. In this case, light can be emitted from the optical modulator 1100 even when light is not incident into the optical modulator 1100. Accordingly, the optical modulator 1100 cannot be used for a beam steering apparatus to modulate the phase of the incident light IL.

[0063] Further, the single gain Gs of the quantum dots 203 can satisfy Gs^2 > 1 / Rb. When the single gain Gs is decreased such that the value of Gs^2 is equal to or less than 1 / Rb, the active layer 200 can have a loss. Accordingly, it is desirable to design the single gain Gs of the quantum dots 203 to satisfy Gs^2 > 1 / Rb so that the active layer 200 has a gain.

[0064] Thus, when the single gain Gs of the quantum dots 203 satisfies 1 / Rb < Gs^2 < 1 / (Rf * Rb), lasing due to spontaneous emission can not occur in the quantum dots 203, and at the same time, the active layer 200 can have a gain.

[0065] The first contact layer 400 can include an N-type contact layer doped with an N-type material, and the second contact layer 500 can include a P-type contact layer doped with a P-type material. Figure 1 It is illustrated that the first contact layer 400 is disposed below the first DBR layer 100. However, it is not limited thereto. For example, the first contact layer 400 can be disposed between the active layer 200 and the first DBR layer 100. Further, Figure 1 It is illustrated that the second contact layer 500 is disposed above the second DBR layer 300. However, it is not limited thereto. For example, the second contact layer 500 can be disposed between the active layer 200 and the second DBR layer 300. An electrode can also be disposed on the first contact layer 400 and the second contact layer 500.

[0066] Reference Figure 2The intensity of the output light OL output from the optical modulator 1100 can increase as the current I applied to the active layer 200 increases. However, when the current reaches a value equal to or greater than a certain value la, the intensity of the output light OL can no longer increase. Accordingly, the active layer 200 can have a saturated gain at an applied current equal to or greater than a certain value la, because only a limited number of electrons among electrons capable of directly participating in causing stimulated emission in the active layer 200 can flow into the ground state of the conduction band of the quantum dot 203. In contrast, the refractive index of the active layer 200 can change even in a region in which the gain of the active layer 200 no longer increases. In other words, the phase p of the incident light IL can change even in a region in which the intensity of the output light OL no longer increases.

[0067] As described above, the optical modulator 1100 can continuously change the phase of the incident light IL while having a saturated gain based on the applied current. As such, the optical modulator 1100 can further include a processor configured to separately control the gain and the refractive index. For example, the processor can separately adjust the refractive index and the gain of the active layer 200 by applying a current between the first DBR layer 100 and the second DBR layer 300. Accordingly, the optical modulator 1100 can effectively control the traveling direction of the incident light IL. Hereinafter, a principle of separately controlling the gain and the refractive index via the optical modulator 1100 will be described. Figure 5

[0068] Figure 3 A process in which the density inversion occurs in the optical modulator 1100 of Figure 1 is schematically illustrated. Figure 4 A process in which the stimulated emission occurs in the optical modulator 1100 of Figure 1 is schematically illustrated. Figure 5 A process in which the refractive index is changed in the optical modulator 1100 is schematically illustrated. In the description of Figure 3 to 5 , reference will be made to the components shown in Figure 1 . As shown in Figure 3 to 5 , the band gap energy Eb of the first barrier layer a1 or a4 can be greater than the band gap energy Ew of the well layer a2. Further, the band gap energy Ew of the well layer a2 can be greater than the band gap energy Ed of the quantum dot 203.

[0069] Reference will be made to Figure 3 ​When the electron staying in the valence band of the quantum dot 203 acquires energy due to the current applied between the first DBR layer 100 and the second DBR layer 300 and moves to the conduction band, the density inversion can occur. For example, the electron staying in the valence band of the quantum dot 203 can acquire energy and can be filled in the ground state S1 of the conduction band. For example, when a current corresponding to the band gap energy Ed of the quantum dot 203 is applied between the first DBR layer 100 and the second DBR layer 300, the electron in the valence band of the quantum dot 203 can acquire energy and move to the conduction band, and thus, the density inversion can occur. When the current is continuously applied, more electrons can move, and thus, the occurrence of the density inversion can increase.

[0070] Referring to Figure 4 The wavelength of the incident light IL can have an energy equal to the band gap energy Ed of the quantum dot 203, and the density inversion can occur in the quantum dot 203. When the incident light IL is incident into the optical modulator 1100, the stimulated emission can occur, and thus, the intensity of the incident light IL can be amplified. Accordingly, the output light OL having a greater intensity than the incident light IL can be output from the optical modulator 1100. At the same time, the electron filled in the ground state S1 of the conduction band of the quantum dot 203 can occur the stimulated emission. As described above, the number of electrons filled in the ground state S1 is limited, and thus, even when the current is continuously applied between the first DBR layer 100 and the second DBR layer 300, the occurrence of the stimulated emission can not increase any more. Accordingly, when the amplification rate reaches a value equal to or greater than a certain value, the amplification rate of the incident light IL can not increase any more, and can be saturated. In other words, when the current having a value greater than or equal to a certain value is applied, the active layer 200 can have a saturated gain.

[0071] Referring to Figure 5As the magnitude of the current between the first DBR layer 100 and the second DBR layer 300 is increased, electrons can be filled in multiple quantized states of the quantum dot a3 and the well layer a2. As described above, the gain of the active layer 200 can be determined by the electrons in the ground state S1 of the conduction band of the quantum dot 203. Separately, the refractive index of the active layer 200 can be determined by the electrons filled in the multiple quantum states of the well layer a2. For example, even after the electrons are completely filled in the multiple states including the ground state S1 of the quantum dot 203, the electrons can be continuously filled in the multiple states of the well layer a2 as the current is continuously applied to the active layer 200. As the number of electrons filled in the well layer a2 changes, the refractive index of the active layer 200 can change. As described above, when the current having a value equal to or greater than a certain value is applied, the gain of the active layer 200 does not increase any more and can be saturated even when the applied current increases. In contrast, even when the gain of the active layer 200 is saturated, the refractive index of the active layer 200 can continuously change as the current is continuously applied to the active layer 200. As such, by applying the current to the active layer 200, the gain and the refractive index can be separately controlled.

[0072] The optical modulator 1110 can include the current source 600 that applies a current between the first DBR layer 100 and the second DBR layer 300 to control the gain of the optical modulator 1110 and the phase of the incident light through the interband transition of the electrons between the valence band and the conduction band of the well layer 202.

[0073] Figure 6 is a lateral cross-sectional view schematically illustrating a structure of the optical modulator 1110 according to another embodiment. When describing Figure 6 the embodiment of Figure 1 the same aspects as those of the embodiment of

[0074] Referring to Figure 6The optical modulator 1110 can include a first DBR layer 110 having a first reflectivity Rb, a second DBR layer 310 having a second reflectivity Rf, and an active layer 210 disposed between the first DBR layer 110 and the second DBR layer 310. The first DBR layer 100 can include two refractive index layers having different refractive indexes from each other and repeatedly alternately stacked. The active layer 210 can be disposed on the first DBR layer 110 and can include a quantum well structure having a stack structure in which a well layer 212 and a first barrier layer 211 are alternately stacked. At least one quantum dot 213 is disposed in the well layer 212. The second DBR layer 310 can be disposed on the active layer 210 and can include two refractive index layers having different refractive indexes from each other and repeatedly alternately stacked. Further, the optical modulator 1110 can further include a first contact layer 410 disposed below the first DBR layer 110 and a second contact layer 510 disposed above the second DBR layer 310. However, it is not limited thereto, and the first contact layer 410 can be disposed between the active layer 210 and the first DBR layer 110. Further, the second contact layer 510 can be disposed between the active layer 210 and the second DBR layer 310.

[0075] The first DBR layer 110 and the second DBR layer 310 can respectively have substantially the same structure as the first DBR layer 100 and the second DBR layer 300 of FIG. 1. Figure 1 For example, the first DBR layer 110 and the second DBR layer 310 can include a structure in which a low refractive index layer 12 having a relatively low refractive index and a high refractive index layer 13 having a relatively high refractive index are alternately stacked.

[0076] The first contact layer 410 and the second contact layer 510 can respectively have substantially the same structure as the first contact layer 400 and the second contact layer 500 of FIG. 1. Figure 1

[0077] The active layer 210 can include a semiconductor material having a quantum well structure. For example, the active layer 210 can include a plurality of stack structures ST1 to STn (n is a natural number) in which the well layer 212 and the first barrier layer 211 are alternately stacked. As the number of the plurality of stack structures ST1 to STn increases, the gain of the active layer 210 can increase.

[0078] Each of the plurality of stack structures ST1 to STn can include at least one quantum dot 213. The quantum dot 213 can have substantially the same structure as the quantum dot 203 of FIG. 1. Figure 2

[0079] Figure 7 is a lateral cross-sectional view schematically illustrating a structure of an optical modulator 1120 according to another embodiment. When describing the embodiment of FIG. 11, the same elements as those of FIG. 1 are designated by the same reference numerals, and a detailed description thereof will be omitted. Figure 7 is a lateral cross-sectional view schematically illustrating a structure of an optical modulator 1120 according to another embodiment. When describing the embodiment of FIG. 11, the same elements as those of FIG. 1 are designated by the same reference numerals, and a detailed description thereof will be omitted.​​Figure 1 Aspects of embodiments of the present application are omitted.

[0080] Referring to Figure 7 , the optical modulator 1120 can include a first DBR layer 120 having a first reflectivity Rb, a second DBR layer 320 having a second reflectivity Rf, and an active layer 220 disposed between the first DBR layer 120 and the second DBR layer 320. The first DBR layer 120 can include two refractive index layers having different refractive indexes from each other and repeatedly alternately stacked. The active layer 220 is disposed on the first DBR layer 120 and can include a quantum well structure having a stack structure in which a well layer 222 and a first barrier layer 221 are alternately stacked, with at least one quantum dot 223 disposed in the well layer 222. The second DBR layer 320 can be disposed on the active layer 220 and can include two refractive index layers having different refractive indexes from each other and repeatedly alternately stacked. Further, the optical modulator 1120 can further include a first contact layer 420 disposed below the first DBR layer 120 and a second contact layer 520 disposed above the second DBR layer 320. However, it is not limited thereto, and the first contact layer 420 can be disposed between the active layer 220 and the first DBR layer 120. Further, the second contact layer 520 can be disposed between the active layer 220 and the second DBR layer 320.

[0081] The first DBR layer 120 and the second DBR layer 320 can respectively have substantially the same structure as the first DBR layer 100 and the second DBR layer 300 of Figure 1 . For example, the first DBR layer 120 and the second DBR layer 320 can include a structure in which a low refractive index layer 14 having a relatively low refractive index and a high refractive index layer 15 having a relatively high refractive index are alternately stacked.

[0082] The first contact layer 420 and the second contact layer 520 can respectively have substantially the same structure as the first contact layer 400 and the second contact layer 500 of Figure 2 .

[0083] The active layer 220 can include a semiconductor material having a quantum well structure. For example, the active layer 220 can include a plurality of stack structures ST1 to ST6 in which the well layer 222 and the first barrier layer 221 are alternately stacked. Figure 7Six stack structures ST1 to ST6 are shown. However, this is not limiting, and there can be more than six stack structures. As the number of stack structures ST1 to ST6 increases, the gain of the active layer 220 can increase. Meanwhile, the active layer 220 can include a first multi-stack structure MS1 having a plurality of stack structures (e.g., the first stack structure ST1 to the third stack structure ST3) and a second multi-stack structure MS2 having a plurality of stack structures (e.g., the fourth stack structure ST4 to the sixth stack structure ST6). However, this is not limiting, and each of the first multi-stack structure MS1 and the second multi-stack structure MS2 can include more or less than three stack structures. In addition, Figure 7 Two multi-stack structures are shown. However, this is not limiting, and the active layer 220 can include more than two multi-stack structures. In addition, the second barrier layer 224 can also be disposed between the first multi-stack structure MS1 and the second multi-stack structure MS2. In addition, the second barrier layer 224 can be disposed between the first multi-stack structure MS1 and the second DBR layer 320. Furthermore, the second barrier layer 224 can be disposed between the second multi-stack structure MS2 and the first DBR layer 120. That is, the optical modulator 1120 can have a plurality of second barrier layers 224. The thickness of the second barrier layer 224 can be greater than the thickness of the first barrier layer 221. Furthermore, the well layer 222 can include at least one quantum dot 223. The quantum dot 223 can have substantially the same structure as the quantum dot 203 of Figure 2

[0084] Figure 8 is a lateral cross-sectional view schematically showing a structure of an optical modulator 1130 according to another embodiment. When aspects of the embodiment of Figure 8 are described, aspects identical to those of the embodiment of Figure 1 are omitted.

[0085] Reference is made to Figure 8 ​The optical modulator 1130 can include a first DBR layer 130 having a first reflectivity Rb, a second DBR layer 330 having a second reflectivity Rf, and an active layer 230 disposed between the first DBR layer 130 and the second DBR. The first DBR layer 130 can include two refractive index layers having different refractive indexes from each other and repeatedly alternately stacked. The active layer 230 can be disposed on the first DBR layer 130 and can include a quantum well structure having a stack structure in which a well layer 232 and a first barrier layer 231 are alternately stacked with at least one quantum dot 233 disposed in the well layer 232. The second DBR layer 330 can be disposed on the active layer 230 and can include two refractive index layers having different refractive indexes from each other and repeatedly alternately stacked. In addition, the optical modulator 1130 can further include a first contact layer 430 disposed below the first DBR layer 130 and a second contact layer 530 disposed above the second DBR layer 330. However, it is not limited thereto, and the first contact layer 430 can be disposed between the active layer 230 and the first DBR layer 130. In addition, the second contact layer 530 can be disposed between the active layer 230 and the second DBR layer 330.

[0086] The first DBR layer 130 and the second DBR layer 330 can have substantially the same structures as the first DBR layer 100 and the second DBR layer 300 of FIG. 1, respectively. For example, the first DBR layer 130 and the second DBR layer 330 can include a structure in which a low refractive index layer 16 having a relatively low refractive index and a high refractive index layer 17 having a relatively high refractive index are alternately stacked. Figure 1

[0087] The first contact layer 430 and the second contact layer 530 can have substantially the same structures as the first contact layer 400 and the second contact layer 500 of FIG. 1, respectively. Figure 2

[0088] The active layer 230 can have the same structure as the active layer 200 of FIG. 1. For example, the active layer 230 can include a stack structure in which the well layer 232 and the first barrier layer 231 are alternately stacked. For example, the well layer 232 can be disposed between a pair of the first barrier layers 231. In addition, the well layer 232 can include at least one quantum dot 233. The quantum dot 233 can have substantially the same structure as the quantum dot 203 of FIG. 1. Figure 1 Figure 1

[0089] ​​​​Furthermore, multiple superstructures 630 can be disposed above the second DBR layer 330. For example, the multiple superstructures 630 can be formed to directly contact the second contact layer 530 disposed above the second DBR layer 330. However, when the second contact layer 530 is disposed between the second DBR layer 330 and the active layer 230, multiple superstructures 630 can be formed to directly contact the second DBR layer 330.

[0090] Multiple superstructures 630 can have shape metrics smaller than the wavelength of the incident light IL. In this case, the incident light IL can also be modulated by passing through the superstructure 630 before outputting the incident light IL with phase and intensity modulated by the active layer 230. Thus, the phase or intensity of the incident light IL can be secondary modulated by the superstructure 630. The degree of secondary modulation of the incident light IL passing through the superstructure 630 can be determined based on the shape metrics of the superstructure 630.

[0091] The shape dimensions of the plurality of metastructures 630 can be smaller than the wavelength of the incident light IL. For example, the height, area, width, spacing, etc., of the plurality of metastructures 630 can be smaller than the wavelength of the incident light IL. At least two of the plurality of metastructures 630 can have different refractive indices from each other. For example, at least two of the plurality of metastructures 630 can have different shape dimensions from each other, such as different heights, areas, widths, spacing, etc., and therefore can have different refractive indices from each other.

[0092] Figure 9 This is a schematic cross-sectional view of the structure of the optical modulator array 2100 according to an embodiment. Figure 10 It is a schematic diagram showing the control Figure 9 A cross-sectional view of the structure of the control circuit 2200 of the optical modulator array 2100. Figure 11 This is a schematic cross-sectional view of a beam steering device 2000 according to an embodiment.

[0093] refer to Figure 9 The optical modulator array 2100 may include a plurality of optical modulators 2110 disposed on the substrate 2120. For example, the plurality of optical modulators 2110 may be coupled with... Figure 1 Optical modulator 1100 Figure 6 Optical modulator 1110 Figure 7 Optical modulator 1120 and Figure 8The light modulators 1130 of the plurality of light modulators 1110 are substantially the same. For example, each of the plurality of light modulators 2110 can include at least one quantum dot. Also, the distribution density of the quantum dots of each of the plurality of light modulators 2110 can be the same. Accordingly, the gain of each of the plurality of light modulators 2110 can be the same. However, not limited thereto, the distribution density of the quantum dots of each of the plurality of light modulators 2110 can be different from each other, and thus the gain of each of the plurality of light modulators 2110 can be different from each other.

[0094] Referring to Figure 10 The control circuit 2200 can include a plurality of transistors Tr1 to Tr4. The first transistor Tr1 can be disposed on the substrate sub and can include a source electrode 1 and a drain electrode 2 facing each other. The source electrode 1 and the drain electrode 2 can be doped with an n-type or a p-type material. A channel layer 3 can be formed between the source electrode 1 and the drain electrode 2. The channel layer 3 can be a region including an n-type material or a p-type material. For example, when both the source electrode 1 and the drain electrode 2 are doped with an n-type material, the channel layer 3 can be a region including a p-type material. In this case, the first transistor Tr1 can be referred to as an n-channel metal oxide semiconductor (NMOS). Alternatively, when both the source electrode 1 and the drain electrode 2 are doped with a p-type material, the channel layer 3 can be a region including an n-type material. In this case, the first transistor Tr1 can be referred to as a p-channel metal oxide semiconductor (PMOS). When the first transistor Tr1 is an NMOS, a second transistor Tr2 adjacent to the first transistor Tr1 can be a PMOS. In this case, the first transistor Tr1 and the second transistor Tr2 can be connected to each other to form a complementary metal oxide semiconductor (CMOS). For example, the drain electrodes 2 of the first transistor Tr1 and the second transistor Tr2 can be connected to each other to form a CMOS. Also, the first transistor Tr1 can further include a gate electrode 4 disposed on the substrate sub on a region corresponding to the channel layer 3. A gate insulating layer 5 can be further disposed between the gate electrode 4 and the channel layer 3. An insulating layer 7 covering the gate electrode 4 can be disposed on the substrate sub. A plurality of holes H can be formed in the insulating layer 7. A plurality of first electrodes E1 and a plurality of second electrodes E2 can be formed in the plurality of holes H. The plurality of first electrodes E1 can contact the plurality of source electrodes 1. Also, the plurality of first electrodes E1 can be formed to be exposed to the outside of the insulating layer 7. The plurality of second electrodes E2 can contact the plurality of drain electrodes 2. The plurality of drain electrodes 2 can be connected to each other in the insulating layer 7. Figure 10 The drain electrodes 2 are not shown to be directly connected to each other, but can be connected to each other through different paths. Figure 10 The control circuit 2200 includes four transistors Tr1 to Tr4. However, for convenience of explanation, the control circuit 2200 can include more than four transistors.

[0095] Referring toFigure 11 The beam steering device 2000 may include an optical modulator array 2100 and a control circuit 2200. The optical modulator array 2100 and the control circuit 2200 may be electrically connected to each other via a bonding portion 2300. For example, the plurality of optical modulators included in the optical modulator array 2100 and the plurality of transistors included in the control circuit 2200 may be electrically connected to each other. For example, the first transistor Tr1 electrically connected to the first optical modulator OM1 may be an NMOS, while the second transistor Tr2 electrically connected to the second optical modulator OM2 adjacent to the first optical modulator OM1 may be a PMOS. In this case, the first transistor Tr1 and the second transistor Tr2 may form a CMOS. In other words, the first optical modulator OM1 and the second optical modulator OM2 adjacent to each other may be electrically connected to a CMOS including the first transistor Tr1 and the second transistor Tr2. (See reference...) Figure 10 As described, the control circuit 2200 may include multiple transistors Tr1 to Tr4, thus allowing for the formation of multiple CMOS sensors. The currents applied to the multiple CMOS sensors included in the control circuit 2200 may be different from each other. Therefore, different electrical signals can be sent to optical modulators electrically connected to the multiple CMOS sensors. Thus, the control circuit 2200 including multiple CMOS sensors can individually control the characteristics of the multiple optical modulators. For example, the control circuit 2200 can individually control the refractive index of the multiple optical modulators. In this case, each of the multiple optical modulators may have the same saturation gain. Therefore, the intensity of light output from each of the multiple optical modulators may be the same.

[0096] Figure 12 This is a block diagram illustrating a schematic structure of an electronic device 3000 according to an embodiment.

[0097] refer to Figure 12 The electronic device 3000 may include: a lighting device 3100 configured to illuminate an object OBJ with light; a sensor 3300 configured to receive light reflected from the object OBJ; and a processor 3200 configured to perform calculations to obtain information about the object OBJ based on the light received from the sensor 3300. The electronic device 3000 may also include a memory 3400 storing code or data for executing the processor 3200.

[0098] The lighting device 3100 may include a light source 3120 and a beam steering device 3110. The light source 3120 can generate light for scanning the object OBJ. The source light may be a pulsed laser beam. The beam steering device 3110 can illuminate the object OBJ by changing the direction of travel of the light from the light source 3120, and may include... Figure 11 Beam steering device 2000. Reference Figure 11It is described that the optical modulators 1100, 1110, 1120, and 1130 described in Figure 1 , Figure 6 , Figure 7 and Figure 8 can be applied to the light beam steering apparatus 2000.

[0099] An optical apparatus for modulating a direction of light from the illumination apparatus 3100 so that the light is directed toward the object OBJ or for additional modulation can also be arranged between the illumination apparatus 3100 and the object OBJ.

[0100] The sensor 3300 can sense light Lr reflected by the object OBJ. The sensor 3300 can include an array of light detection elements. The sensor 3300 can also include a spectral apparatus for analyzing light reflected from the object OBJ for each wavelength. In Figure 12 , the illumination apparatus 3100 and the sensor 3300 can be integrated into a single sensing apparatus, and in this case, the illumination apparatus 3100 and the sensor 3300 can perform light emission and light detection operations, respectively.

[0101] The processor 3200 can perform a calculation for obtaining information about the object OBJ from light received from the sensor 3300. In addition, the processor 3200 can perform overall processing and control of the electronic device 3000. The processor 3200 can obtain and process information about the object OBJ. For example, the processor 3200 can obtain and process two-dimensional or three-dimensional image information. In addition, the processor 3200 can operate a light source included in the illumination apparatus 3100 or overall control the operation of the sensor 3300. For example, the processor 3200 can calculate a value of a current applied to the optical modulator included in the illumination apparatus 3100. The processor 3200 can determine whether a user is authenticated or the like based on information obtained from the object OBJ, and can perform other applications.

[0102] The memory 3400 can store code for execution by the processor 3200. In addition, the memory 3400 can store various execution modules executed by the electronic device 3000 and data for the execution modules. For example, the memory 3400 can store program code used by the processor 3200 to perform a calculation for obtaining information about the object OBJ, and code such as an application module executed by using information about the target object OBJ. In addition, the memory 3400 can also store a communication module, a camera module, a video play module, an audio play module, and the like, as programs for driving apparatuses that can be additionally provided in the electronic device 3000.

[0103] After the calculation of the processor 3200, information about the shape and position of the object OBJ can be transmitted to other devices or units as needed. For example, information about the object OBJ can be transmitted to a controller of another electronic device that uses information about the object OBJ. The other units to which the information is transmitted can include a display device or a printer that outputs a result. In addition, the other units can be, but are not limited to, a smartphone, a cellular phone, a personal digital assistant (PDA), a laptop computer, a personal computer (PC), various wearable devices, and other mobile or non-mobile computing devices.

[0104] The memory 3400 can include a flash memory type memory, a hard disk type memory, a multimedia micro memory, a card type memory (e.g., an SD or XD memory), a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), a magnetic memory, a magnetic disk, and an optical disk, etc.

[0105] The electronic device 3000 can include, for example, a portable mobile communication device, a smartphone, a smart watch, a PDA, a laptop computer, a PC, other mobile or non-mobile computing devices, but the electronic device 3000 is not limited thereto. In addition, the electronic device 3000 can include an autonomous driving machine (e.g., a self-driving vehicle, an autonomous vehicle, a robot, a drone, etc.) or an Internet of Things (IoT) device.

[0106] According to various embodiments of the present disclosure, the phase and intensity of light can be individually controlled by using an optical modulator having a saturated gain.

[0107] According to various embodiments of the present disclosure, the direction of travel of light can be effectively modulated by using an optical beam steering device including an optical modulator having a saturated gain.

[0108] Although not limited thereto, the example embodiments can be implemented as computer readable code on a computer readable recording medium. The computer readable recording medium is any data storage device that can store data which can be thereafter read by a computer system. Examples of the computer readable recording medium include read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, and optical data storage devices. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. In addition, the example embodiments can be written as computer programs and can be implemented in general-use or special-purpose digital computers that are programmed with computer readable codes. Furthermore, it is understood that one or more units of the above-described apparatus and device can include circuitry, a processor, a microprocessor, etc., and can execute computer programs stored in a computer readable medium.

[0109] The above-described example embodiments are merely examples and should not be construed as limiting. The present teachings can be readily applied to other types of apparatuses. Furthermore, the description of the example embodiments is intended to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.

Claims

1. An optical modulator for amplifying the intensity of incident light and modulating the phase of the incident light, the optical modulator comprising: A first distributed Bragg reflector (DBR) layer has a first reflectivity and includes at least two first refractive index layers that have different refractive indices from each other and are repeatedly and alternately stacked. The second DBR layer has a second reflectivity and includes at least two second refractive index layers that have different refractive indices from each other and are repeatedly and alternately stacked. An active layer is disposed between the first DBR layer and the second DBR layer, and includes a quantum well structure; as well as The processor is configured to individually modulate the refractive index and gain of the active layer by applying a current between the first DBR layer and the second DBR layer. The active layer exhibits saturation gain when the applied current is greater than or equal to a predetermined value. The processor modulates the refractive index and gain of the active layer by varying the applied current within a range less than or equal to the saturation gain. The processor modulates the refractive index of the active layer individually within a range exceeding the saturation gain.

2. The optical modulator according to claim 1, wherein, The quantum well structure includes at least one quantum dot, which has a single gain satisfying Gs^2*Rf*Rb<1, and Wherein, Gs, Rf, and Rb represent the single gain, the second reflectivity, and the first reflectivity, respectively.

3. The optical modulator according to claim 1, wherein, The quantum well structure includes at least one quantum dot, which has a single gain satisfying Gs^2 > 1 / Rb, and Wherein, Gs and Rb represent the single gain and the first reflectivity, respectively.

4. The optical modulator according to claim 1, wherein, The quantum well structure includes a well layer and a barrier layer, and the well layer includes a plurality of quantum dots.

5. The optical modulator according to claim 1, wherein, The active layer includes multiple stacked structures, and each of the multiple stacked structures includes alternately stacked well layers and barrier layers.

6. The optical modulator according to claim 1, wherein, The active layer includes: A first multi-stacked structure having a first plurality of stacked structures, and a second multi-stacked structure having a second plurality of stacked structures.

7. The optical modulator of claim 6 further includes a blocking layer between the first multi-stack structure and the second multi-stack structure.

8. The optical modulator according to claim 1, wherein, The quantum well structure of the active layer includes a first multi-stacked structure and a second multi-stacked structure. Each of the first multi-stacked structure and the second multi-stacked structure includes alternately stacked well layers and first barrier layers. The optical modulator further includes a second blocking layer, which is disposed between the first multi-stack structure and the second multi-stack structure. The thickness of the second barrier layer is greater than the thickness of the first barrier layer.

9. The optical modulator according to claim 1, wherein, The quantum well structure of the active layer includes at least one quantum dot, and the band gap energy of the at least one quantum dot is equal to the energy of the incident light.

10. The optical modulator according to claim 1, wherein, The first reflectivity is greater than the second reflectivity.

11. The optical modulator according to claim 1, further comprising a plurality of superstructures disposed on the second DBR layer.

12. The optical modulator according to claim 11, wherein, At least two of the multiple superstructures have different refractive indices from each other.

13. The optical modulator according to claim 1 further includes a first contact layer disposed on the first DBR layer and a second contact layer disposed on the second DBR layer.

14. A beam steering device includes: An optical modulator array including a plurality of optical modulators, the plurality of optical modulators including the optical modulator according to claim 1, and the plurality of optical modulators having the same structure; And A control circuit configured to individually control the refractive indices of the plurality of optical modulators.

15. The beam steering device according to claim 14, wherein, The plurality of optical modulators have the same quantum dot distribution density.

16. The beam steering device according to claim 14, wherein, The control circuit includes a plurality of complementary metal oxide semiconductor (CMOS) devices, and each CMOS device is connected to two adjacent optical modulators among the plurality of optical modulators.

17. An electronic device includes: A light source; The beam steering device according to claim 14, the beam steering device being configured to modulate the traveling direction of light incident from the light source toward an object; A sensor configured to receive light reflected from the object; And A processor configured to analyze the light received by the sensor.

18. The electronic device according to claim 17, wherein, The quantum well structure of the active layer includes at least one quantum dot, the at least one quantum dot having a single gain satisfying 1 / Rb < Gs^2 < 1 / (Rf * Rb), and where Gs, Rb, and Rf respectively represent the single gain, the first reflectivity, and the second reflectivity.

19. An optical sensor including an optical modulator, the optical modulator including: A first distributed Bragg reflector (DBR) layer; A second DBR layer; And A quantum well disposed between the first DBR layer and the second DBR layer, wherein the optical sensor is configured to apply a current between the first DBR layer and the second DBR layer to control the gain of the optical modulator and the phase of incident light through an interband transition of electrons between the valence band and the conduction band of the quantum well, where a processor in the optical modulator individually modulates the phase of the incident light and the gain of the optical modulator by applying a current between the first DBR layer and the second DBR layer, where the quantum well has a saturated gain when the value of the applied current is greater than or equal to a predetermined value, where the processor modulates the refractive index and the gain of the quantum well by changing the applied current within a range less than or equal to the saturated gain, and where the processor individually modulates the refractive index of the quantum well within a range exceeding the saturated gain.

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