Light redirecting device and optical system including the light redirecting device

Abstract

Provided are a light steering device including a tunable laser source and an optical system including the light steering device. The light steering device includes a tunable laser source and a steering device. Multiple laser beams having mutual optical coherence and output from the tunable laser source are incident on the steering device, and the steering device includes multiple modulation units for beam steering.

Description

Technical Field

[0001] Devices consistent with example embodiments relate to light redirecting devices, and more particularly, to light redirecting devices using a tunable laser source and optical systems including the light redirecting devices. Background Art

[0002] In order to steer the laser beam to a desired position, a method of mechanically rotating the laser output portion, and a method of utilizing the coherence of multiple laser beams output from multiple unit cells or multiple waveguides by using an optical phased array (OPA) method as a non-mechanical driving method have been used. In particular, a light steering device has been studied in which a light emission angle depending on the characteristics of a diffraction grating is controlled by using a tunable laser source as a light source to achieve two-dimensional light steering using a diffraction structure arranged in one dimension. Summary of the invention

[0003] One or more example embodiments may provide a light redirecting apparatus using a tunable laser light source and an optical system including the light redirecting apparatus.

[0004] Additional example aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the example embodiments.

[0005] According to one aspect of an example embodiment, a light steering device includes: a tunable laser source; and a steering device, wherein a plurality of laser beams having optical coherence with each other and output from the tunable laser source are incident on the steering device, and the steering device includes a plurality of modulation units for beam steering.

[0006] The tunable laser source and the steering device may be connected to each other via a plurality of input / output connection structures corresponding to the plurality of laser beams.

[0007] The tunable laser source may include first and second waveguides, and first and second ring resonators spaced apart from each other between the first and second waveguides.

[0008] The tunable laser source may include an optical amplifier on at least one of the first waveguide and the second waveguide.

[0009] Each of the first ring resonator and the second ring resonator may include a ring waveguide and a modulator.

[0010] The modulator may include: a heating element configured to heat the ring waveguide; an electrode element configured to change the current density of the ring waveguide by applying a current around the ring waveguide; or a piezoelectric element configured to change the refractive index of the ring waveguide or the refractive index of the material surrounding the ring waveguide according to the application of voltage.

[0011] The plurality of laser beams may include a first laser beam and a second laser beam outputted from one side of the first waveguide and one side of the second waveguide, respectively, so as to ensure optical coherence, the one side of the first waveguide and the one side of the second waveguide being located in a diagonal direction with respect to each other.

[0012] The first output port and the second output port may be provided at both sides of the first waveguide, respectively, and the third output port and the fourth output port may be provided at both sides of the second waveguide, respectively.

[0013] The steering device may include a third waveguide and a fourth waveguide on which the first laser beam and the second laser beam are incident, respectively.

[0014] The first waveguide and the third waveguide may be integrally formed, and the second waveguide and the fourth waveguide may be integrally formed.

[0015] The steering device may further include a splitter configured to split each of the third waveguide and the fourth waveguide into a plurality of waveguides.

[0016] The plurality of modulation units may be configured to modulate a phase of the light beam passing through the branched third waveguide and fourth waveguide.

[0017] There may be a time-independent phase difference between the first laser beam and the second laser beam.

[0018] The light redirecting device may further include a phase difference compensation device configured to compensate for a phase difference between the first laser beam and the second laser beam.

[0019] The phase difference compensation device may be provided on at least one of a path of the first laser beam and a path of the second laser beam, and is further configured to apply an electrical signal corresponding to a phase difference between the first laser beam and the second laser beam.

[0020] At least one of the plurality of modulation units may be configured to apply an electrical signal corresponding to a phase difference between the first laser beam and the second laser beam.

[0021] The light output portions of the diverting device may be arranged in a one-dimensional array.

[0022] According to one aspect of another example embodiment, an optical system includes: a tunable laser source; a steering device, a plurality of laser beams having optical coherence with each other and output from the tunable laser source are incident on the steering device, the steering device including a plurality of modulation units for beam steering; and a detection unit configured to detect the beams redirected by the steering device.

[0023] The tunable laser source may include first and second waveguides, first and second ring resonators spaced apart from each other between the first and second waveguides, and an optical amplifier provided on at least one of the first and second waveguides.

[0024] The plurality of laser beams may include first and second laser beams outputted from one side of a first waveguide and one side of a second waveguide, respectively, in order to ensure optical coherence, the one side of the first waveguide and the one side of the second waveguide being located in a diagonal direction with respect to each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] These and / or additional example aspects and advantages will become apparent and more readily understood from the following description of example embodiments in conjunction with the accompanying drawings, in which:

[0026] Figure 1 is a top view of a light redirecting device according to an example embodiment;

[0027] Figure 2 yes Figure 1 A magnified view of the tunable laser source;

[0028] Figure 3 is along Figure 2 A cross-sectional view taken along line III-III';

[0029] Figure 4 is along Figure 2 A cross-sectional view taken along line IV-IV';

[0030] Figure 5 yes Figure 1 A cross-sectional view of a light output portion of a steering device;

[0031] Figure 6 is a top view of a light redirecting device according to another example embodiment;

[0032] Figure 7 is a top view of a light redirecting device according to another example embodiment;

[0033] Figure 8 is a top view of a light redirecting device according to another example embodiment;

[0034] Fig. 9 is a top view of a light redirecting device according to another example embodiment;

[0035] Fig.10 is a top view of a light redirecting device according to another example embodiment; and

[0036] Fig.11 An optical system according to another example embodiment is schematically shown. DETAILED DESCRIPTION

[0037] Reference will now be made in detail to the example embodiments shown in the accompanying drawings, in which the same reference numerals always refer to the same elements. Moreover, for ease of explanation and clarity, the size of each layer shown in the figures may be exaggerated. In this regard, the present example embodiments may have different forms and should not be construed as being limited to the description set forth herein. Therefore, by reference to the accompanying drawings, the example embodiments are described below only for explaining aspects of this specification. In a layer structure, when a constituent element is disposed "above" or "on" another constituent element, the constituent element may be directly only on or above the other constituent element in a non-contact manner.

[0038] Figure 1 is a top view of a light redirecting device according to an example embodiment.

[0039] Reference Figure 1 , the light steering device may include a tunable laser source 100 and a steering device 200, the steering device 200 being used to steer the light output from the tunable laser source 100 in a desired direction. The tunable laser source 100 and the steering device 200 may be integrated on a substrate 50. For example, a silicon substrate may be used as the substrate 50. However, the present disclosure is not limited thereto, and a substrate having any of a variety of materials may be used for the substrate 50. ( Figure 3 A cladding layer 51 (shown) may be provided on the upper surface of the substrate 50. Although the cladding layer 51 may include, for example, silicon oxide, the present disclosure is not limited thereto. The tunable laser source 100 may vary the wavelength of the laser beam to a wide bandwidth as described below.

[0040] Figure 2 yes Figure 1 An enlarged view of the tunable laser source 100 is shown. Figure 3 is along Figure 2 A cross-sectional view taken along line III-III'. Figure 4 is along Figure 2 A cross-sectional view taken along line IV-IV'.

[0041] Reference Figures 2 to 4 The tunable laser source 100 may be, for example, a tunable laser diode. The tunable laser source 100 may include a first waveguide 111 and a second waveguide 112 , and a first ring resonator 125 and a second ring resonator 126 provided between the first waveguide 111 and the second waveguide 112 .

[0042] The first waveguide 111 and the second waveguide 112 may be arranged, for example, in parallel with each other. The first waveguide 111 and the second waveguide 112 may each include a semiconductor material. For example, the first waveguide 111 and the second waveguide 112 may each include silicon. However, this is exemplary, and the first waveguide 111 and the second waveguide 112 may include any of various other materials. The first waveguide 111 and the second waveguide 112 may be provided with a first optical amplifier 141 and a second optical amplifier 142, respectively, which will be described later.

[0043] The first ring resonator 125 and the second ring resonator 126 may be spaced apart from each other between the first waveguide 111 and the second waveguide 112. Figure 3 , a cross section of the first ring resonator 125 is exemplarily shown, and the second ring resonator 126 may have the same cross-sectional structure as the first ring resonator 125. The first ring resonator 125 may include a first ring waveguide 121 and a first modulator 131. The second ring resonator 126 may include a second ring waveguide 122 and a second modulator 132.

[0044] The first ring waveguide 121 and the second ring waveguide 122 may include the same material, such as the material of the first waveguide 111 and the second waveguide 112 , for example, a semiconductor material such as silicon. The first modulator 131 may modulate the propagation constant of the first ring waveguide 121 , and the second modulator 132 may modulate the propagation constant of the second ring waveguide 122 .

[0045] Each of the first modulator 131 and the second modulator 132 may include, for example, a heating element, an electrode element, or a piezoelectric element. The heating element may change the length of the corresponding ring waveguide by applying heat to the corresponding ring waveguide of the first ring waveguide 121 and the second ring waveguide 122, and the refractive index change of the corresponding ring waveguide generated thereby may change the oscillation wavelength to a wide bandwidth. The electrode element may change the current density in the corresponding ring waveguide by applying a current around the corresponding ring waveguide of the first ring waveguide 121 and the second ring waveguide 122, and the refractive index change of the corresponding ring waveguide generated thereby may change the oscillation wavelength to a wide bandwidth. Due to the deformation according to the application of voltage, the piezoelectric element may change the refractive index of the corresponding ring waveguide of the first ring waveguide 121 and the second ring waveguide 122, or the refractive index of the material surrounding the corresponding ring waveguide of the first ring waveguide 121 and the second ring waveguide 122, and thus change the oscillation wavelength to a wide bandwidth.

[0046] Although Figure 2The case where the first modulator 131 and the second modulator 132 are provided inside the first ring waveguide 121 and the second ring waveguide 122, respectively, is exemplarily shown, but example embodiments are not limited thereto, and shapes and positions of the first modulator 131 and the second modulator 132 may be modified in any of various ways.

[0047] The first optical amplifier 141 and the second optical amplifier 142 may be provided on the first waveguide 111 and the second waveguide 112, respectively. The first optical amplifier 141 may be provided on the first waveguide 111 between the first ring resonator 125 and the second ring resonator 126, and the second optical amplifier 142 may be provided on the second waveguide 112 between the first ring resonator 125 and the second ring resonator 126. The first optical amplifier 141 and the second optical amplifier 142 may include, for example, a semiconductor optical amplifier or an ion-doped amplifier. The first optical amplifier 141 and the second optical amplifier 142 may perform optical amplification and optical generation simultaneously.

[0048] Figure 4 1 is a schematic cross-sectional view of the first optical amplifier 141 of the first optical amplifier 141 and the second optical amplifier 142 as semiconductor optical amplifiers. The second optical amplifier 142 may have the same cross-sectional structure as the first optical amplifier 141. Figure 4 , the first optical amplifier 141 may include, for example, a lower cladding layer 143, an active layer 144, and an upper cladding layer 145. The lower cladding layer 143 and the upper cladding layer 145 may include, for example, a III-V compound semiconductor material or a II-VI compound semiconductor material. The active layer 144 may include, for example, InGaAs, InGaNAs, InGaAsP, or InAlGaAs. The lower cladding layer 143 and the upper cladding layer 145 may include a semiconductor material having a band gap larger than that of the active layer 144. The lower cladding layer 143 and the upper cladding layer 145 may include, for example, GaAs, GaP, AlGaAs, InGaP, GaAs, or InP. The material forming the first optical amplifier 141 may be selected according to the wavelength (or band gap) of the light to be amplified. For example, when light having a wavelength of about 1.55 μm is to be amplified, InP / InGaAs material may be used for the lower cladding layer 143 and the upper cladding layer 145 and the active layer 144.

[0049] A conductive layer 147 may be provided on the lower cladding layer 143 and the upper cladding layer 145. The conductive layer 147 may include, for example, at least one material selected from the group consisting of Ti, Au, Ag, Pt, Cu, Al, Ni, and Cr, an alloy thereof, or a stack thereof. However, example embodiments are not limited thereto, and the conductive layer 147 may include, for example, at least one of indium tin oxide (ITO), indium zinc oxide (IZO), Ga-In-Zn oxide (GIZO), Al-Zn oxide (AZO), Ga-Zn oxide (GZO), and ZnO. The conductive layer 147 may be used as an electrode, or a separate electrode may be coupled to the conductive layer 147.

[0050] The first optical amplifier 141 or the second optical amplifier 142 as a semiconductor optical amplifier does not require a separate excitation laser, and the optical signal can be generated and amplified by applying an electric field to both sides of the first waveguide 111 and the second waveguide 112. In detail, when an electric field is applied through the conductive layer 147, absorption and stimulated emission of photons occur. When a photon is absorbed, an electron-hole pair is generated. On the contrary, when the electron-hole pair is recombined, stimulated emission of photons occurs. In order to amplify the optical signal, stimulated emission of photons occurs more than absorption of photons. The semiconductor optical amplifier may include a Fabry-Perot amplifier (FPA) type and a traveling wave amplifier (TWA) type. According to the FPA type, population inversion occurs in the conduction band as a high energy level due to the injection current, and thus stimulated emission can occur due to transition to the valence band as a low energy level, and can be amplified by a resonator. According to the TWA type, both end faces of the semiconductor laser are coated with an anti-reflection layer to limit reflection from the emission surface, and the resonance phenomenon is limited so that the gain bandwidth can be increased compared to the FPA type. The first and second optical amplifiers 141 and 142 may have widths greater than those of the first and second waveguides 111 and 112. Therefore, loss of light transmitted through the first and second waveguides 111 and 112 during movement toward the first and second optical amplifiers 141 and 142 may be reduced.

[0051] In the tunable laser source 100 having the above structure, light generated from at least one of the first optical amplifier 141 and the second optical amplifier 142 may be amplified by passing through the first ring resonator 125 and the second ring resonator 126 clockwise and counterclockwise, and then may be output to the outside at a desired oscillation wavelength through the first waveguide 111 and the second waveguide 112. For example, Figure 2 As shown, the first laser beam L1 may be output from both sides of the first waveguide 111, and the second laser beam L2 may be output from both sides of the second waveguide 112. In this state, the first laser beam L1 output from both sides of the first waveguide 111 and the second laser beam L2 output from both sides of the second waveguide 112 may have the same wavelength and the same output power.

[0052] All of the first laser beam L1 and the second laser beam L2 output from the tunable laser source 100 are output from opposite ends of the first waveguide and the second waveguide (ie, as shown in FIG. 1 ). Figure 2 As shown, the first laser beam L1 and the second laser beam L2 (located in diagonal directions relative to each other) have guaranteed mutual optical coherence. Figure 2 , the first laser beam L1 output from the first side of the first waveguide 111 (i.e., the first waveguide 111 located on the left side of the first optical amplifier 141) and the second laser beam L2 output from the second side of the second waveguide 112 located in the diagonal direction relative to the first side of the first waveguide 111 (i.e., the second waveguide 112 located on the right side of the second optical amplifier 142) can have ensured mutual optical coherence. As such, when the first laser beam L1 and the second laser beam L2 having mutual optical coherence are used in the light redirecting device, compared with the case of using a single laser beam, approximately twice the optical output power can be obtained while consuming the same power.

[0053] At the same time, the first laser beam L1 output from the second side of the first waveguide 111 (i.e., the first waveguide 111 located on the right side of the first optical amplifier 141) and the second laser beam L2 output from the first side of the second waveguide 112 located in a diagonal direction on the second side of the first waveguide 111 (i.e., the second waveguide 112 on the left side of the second optical amplifier 142) can have ensured optical coherence with each other, which is discussed in the example embodiment described below.

[0054] There may be a phase difference between the first laser beam L1 and the second laser beam L2 having optical coherence. However, since the phase difference in this case is a phase difference that is independent of time, the phase difference problem can be solved by compensating the phase difference of any one of the first laser beam L1 and the second laser beam L2 by using a phase difference compensation device as described below. Although the first waveguide 111 and the second waveguide 112 are provided with the first optical amplifier 141 and the second optical amplifier 142, respectively, in the above description, the optical amplifier may be provided to only one of the first waveguide 111 and the second waveguide 112.

[0055] Return to reference Figure 1 The steering device 200 can steer light in a desired direction by using the first laser beam L1 and the second laser beam L2 having optical coherence and output from the tunable laser source 100. The steering device 200 may include a third waveguide 211 and a fourth waveguide 212, a plurality of splitters 251 and 252, and a plurality of modulation units 271 and 272.

[0056] The first laser beam L1 output from the first side of the first waveguide 111 of the tunable laser source 100 may be incident on the third waveguide 211 of the steering device 200, and the second laser beam L2 output from the second side of the second waveguide 112 of the tunable laser source 100 may be incident on the fourth waveguide 212 of the steering device 200. The third waveguide 211 and the fourth waveguide 212 may include a semiconductor material such as silicon. However, this is exemplary, and the third waveguide 211 and the fourth waveguide 212 may include any other various materials.

[0057] The third waveguide 211 of the steering device 200 may be integrally formed with the first waveguide 111 of the tunable laser source 100 , and the fourth waveguide 212 of the steering device 200 may be integrally formed with the second waveguide 112 of the tunable laser source 100 .

[0058] The phase difference compensation device 151 may be provided on the third waveguide 211. As described above, there may be a time-independent phase difference between the first laser beam L1 and the second laser beam L2 having optical coherence incident on the third waveguide 211 and the fourth waveguide 212. The phase difference compensation device 151 may compensate for the phase difference between the first laser beam L1 and the second laser beam L2 by applying an electrical signal corresponding to the phase difference between the first laser beam L1 and the second laser beam L2 to the third waveguide 211 through which the first laser beam L1 passes. Therefore, the first laser beam L1 passing through the third waveguide 211 via the phase difference compensation device 151 may have the same phase as the second laser beam L2 passing through the fourth waveguide 212.

[0059] Although Figure 1 The case where the phase difference compensation device 151 is provided on the third waveguide 211 of the steering device 200 is exemplarily shown, but the phase difference compensation device 151 may be provided on the first waveguide 111 of the tunable laser source 100. In addition, the phase difference compensation device 151 may be provided on the fourth waveguide 212, or provided on both the third waveguide 211 and the fourth waveguide 212.

[0060] The splitters 251 and 252 can respectively split the third waveguide 211 and the fourth waveguide 212 into a plurality of waveguides. Figure 1 , the third waveguide 211 and the fourth waveguide 212 are respectively branched into four waveguides by the first brancher 251 and the second brancher 252, thus showing a case where there are a total of eight (8) third waveguides 211 and fourth waveguides 212. However, this is exemplary, and the number of branchers 251 and 252 and the number of the third waveguides 211 and the fourth waveguides 212 after branching may be modified in any of various ways.

[0061] The modulation units 271 and 272 may respectively modulate the phases of the first laser beam L1 and the second laser beam L2 passing through the branched third waveguide 211 and the fourth waveguide 212. In this state, the modulation units 271 and 272 may independently modulate the phases of the first laser beam L1 and the second laser beam L2 passing through the third waveguide 211 and the fourth waveguide 212. Therefore, a phase distribution profile of the first laser beam L1 and the second laser beam L2 passing through the third waveguide 211 and the fourth waveguide 212, respectively, via the modulation units 271 and 272 may be formed.

[0062] In order to modulate the phases of the first laser beam L1 and the second laser beam L2 passing through the third waveguide 211 and the fourth waveguide 212, respectively, for example, the following method may be used: the refractive index of the third waveguide 211 and the fourth waveguide 212 is changed by applying heat or an electric signal to the third waveguide 211 and the fourth waveguide 212 via the modulation units 271 and 272. As another method, each of the modulation units 271 and 272 includes a cladding layer (not shown) having a refractive index that changes according to the application of an electric signal, and the refractive index of the cladding layer is changed by applying an electric signal to the cladding layer, thereby changing the phases of the first laser beam L1 and the second laser beam L2 passing through the third waveguide 211 and the fourth waveguide 212.

[0063] The modulation units 271 and 272 may include a first modulation unit 271 provided on the branched third waveguide 211 and a second modulation unit 272 provided on the branched fourth waveguide 212. Each first modulation unit 271 may independently modulate the phase of the first laser beam L1 passing through each third waveguide 211, and each second modulation unit 272 may independently modulate the phase of the second laser beam L2 passing through each fourth waveguide 212.

[0064] The first laser beam L1 and the second laser beam L2 having phases independently modulated by the first modulation unit 271 and the second modulation unit 272 may be output to the outside through the light output portion 290 provided at the ends of the third waveguide 211 and the fourth waveguide 212. The light output portion 290 of the steering device 200 may be arranged on the substrate 50 in the form of a one-dimensional array.

[0065] Figure 5 yes Figure 1 2 is a cross-sectional view of the light output portion 290 of the deflection device 200. Figure 5, the light output portion 290 may have a grating structure in which a plurality of grooves 215 are periodically formed in the third waveguide 211 or the fourth waveguide 212. By interference between the first laser beam L1 and the second laser beam L2 emitted by the grating structure of the light output portion 290, light may be output, for example, in the +z-axis direction. In this case, by changing the phase distribution profile of the first laser beam L1 and the second laser beam L2 via the first modulation unit 271 and the second modulation unit 272, the light beam output from the light output portion 290 is steered, for example, in the +y-axis and -y-axis directions, and by changing the wavelengths of the first laser beam L1 and the second laser beam L2 using the tunable laser source 100, the light beam output from the light output portion 290 is steered, for example, in the +x-axis and -x-axis directions, thereby achieving two-dimensional light steering.

[0066] like Figure 1 As shown, optical amplifiers 261 and 262 for amplifying the first laser beam L1 and the second laser beam L2 may be provided on the branched third waveguide 211 and the fourth waveguide 212 as necessary. Figure 1 The positions where the optical amplifiers 261 and 262 are provided are exemplarily shown here. The positions of the optical amplifiers 261 and 262 may be changed in any of various ways. The optical amplifiers 261 and 262 may include, for example, semiconductor optical amplifiers or ion-doped amplifiers.

[0067] In the light redirecting device according to the present exemplary embodiment, since light is redirected by simultaneously using two first laser beams L1 and second laser beams L2 having optical coherence among the first laser beam L1 and the second laser beam L2 output from the tunable laser source 100, the light output power can be increased without losing the redirecting performance compared to the case of using a single laser beam. In addition, when the maximum light output power of the light redirecting device is limited, power consumption can be reduced, and the same light output power can be achieved even when the number of elements forming the light redirecting device is reduced.

[0068] Figure 6 is a top view of a light redirecting device according to another exemplary embodiment. The following description mainly focuses on the differences from the above-mentioned embodiment.

[0069] Reference Figure 6 The light steering device may include a tunable laser source 101 and a steering device 201, wherein the steering device 201 is used to steer the light output from the tunable laser source 101 in a desired direction. The tunable laser source 101 may include a first waveguide 111 and a second waveguide 112 arranged in parallel with each other, and a first ring resonator 125 and a second ring resonator 126 between the first waveguide 111 and the second waveguide 112. The first waveguide 111 may be provided with a first optical amplifier 141, and the second waveguide 112 may be provided with a second optical amplifier 142.

[0070] The first laser beam L1 may be output from both sides of the first waveguide 111, and the second laser beam L2 may be output from both sides of the second waveguide 112. All of the first laser beam L1 output from both sides of the first waveguide 111 and the second laser beam L2 output from both sides of the second waveguide 112 are output from opposite ends of the first waveguide and the second waveguide (i.e., as Figure 6 As shown, the first laser beam L1 and the second laser beam L2 (located in a diagonal direction relative to each other) have guaranteed optical coherence with each other.

[0071] Different from the above exemplary embodiment, in this exemplary embodiment, the first waveguide 111 (located on the right side of the first optical amplifier 141) Figure 6 The first laser beam L1 outputted from the second side of the first waveguide 111 at the top and the second waveguide 112 (located on the left side of the second optical amplifier 142, i.e., located on the left side of the second optical amplifier 142) located in the diagonal direction relative to the second side of the first waveguide 111 are Figure 6 The second laser beam L2 outputted from the first side of the second waveguide 112 at the lower part is used. There may be a time-independent phase difference between the first laser beam L1 and the second laser beam L2 having optical coherence, but the phase difference problem can be solved by the phase difference compensation device 151 described below.

[0072] The steering device 201 may steer light in a desired direction by using first and second laser beams L1 and L2 having optical coherence and output from the tunable laser source 101 , and may include third and fourth waveguides 211 and 212 , splitters 251 and 252 , and modulation units 271 and 272 .

[0073] In the present example embodiment, the first laser beam L1 output from the second side of the first waveguide 111 of the tunable laser source 101 may be incident on the fourth waveguide 212 of the steering device 201, and the second laser beam L2 output from the first side of the second waveguide 112 of the tunable laser source 101 may be incident on the third waveguide 211 of the steering device 201. In this case, the fourth waveguide 212 of the steering device 201 may be integrally formed with the first waveguide 111 of the tunable laser source 101, and the third waveguide 211 of the steering device 201 may be integrally formed with the second waveguide 112 of the tunable laser source 101.

[0074] The phase difference compensation device 151 may be provided on the fourth waveguide 212. The phase difference compensation device 151 may compensate for the phase difference between the first laser beam L1 and the second laser beam L2 by applying an electrical signal corresponding to the phase difference between the first laser beam L1 and the second laser beam L2 to the fourth waveguide 212 through which the first laser beam L1 passes. The phase difference compensation device 151 may be provided on the first waveguide 111 of the tunable laser source 101. Alternatively, the phase difference compensation device 151 may be provided on the second waveguide 112 of the tunable laser source 101, or provided on both the third waveguide 211 and the fourth waveguide 212 of the steering device 201.

[0075] The first laser beam L1 incident on the fourth waveguide 212 of the steering device 201 may pass through the fourth waveguide 212 branched by the splitters 251 and 252, and the second laser beam L2 incident on the third waveguide 211 of the steering device 201 may pass through the third waveguide 211 branched by the splitters 251 and 252. The modulation units 271 and 272 may include a first modulation unit 271 provided on the branched third waveguide 211 and a second modulation unit 272 provided on the branched fourth waveguide 212. Each first modulation unit 271 may independently modulate the phase of the second laser beam L2 passing through each third waveguide 211, and each second modulation unit 272 may independently modulate the phase of the first laser beam L1 passing through each fourth waveguide 212.

[0076] The first laser beam L1 and the second laser beam L2 having phases independently modulated by the first modulation unit 271 and the second modulation unit 272 may be output to the outside through the light output portion 290 provided at the ends of the third waveguide 211 and the fourth waveguide 212. The light output portion 290 of the steering device 201 may be arranged on the substrate 50 in the form of a one-dimensional array.

[0077] Figure 7 is a top view of a light redirecting device according to another example embodiment.

[0078] Reference Figure 7 The light steering device may include a tunable laser source 102 and a steering device 202, wherein the steering device 202 is used to steer the light output from the tunable laser source 102 in a desired direction. The tunable laser source 102 may include a first waveguide 111 and a second waveguide 112 arranged in parallel with each other, and a first ring resonator 125 and a second ring resonator 126 between the first waveguide 111 and the second waveguide 112. A first optical amplifier 141 may be provided on the first waveguide 111, and a second optical amplifier 142 may be provided on the second waveguide 112.

[0079] The first output port 111a and the second output port 111b are provided at opposite sides of the first waveguide 111, and the third output port 112a and the fourth output port 112b are provided at opposite sides of the second waveguide 112. The first laser beam L1 may be output from each of the first output port 111a and the second output port 111b of the first waveguide 111, and the second laser beam L2 may be output from each of the third output port 112a and the fourth output port 112b of the second waveguide 112.

[0080] The first laser beam L1 and the second laser beam L2 output from opposite ends of the first waveguide and the second waveguide (i.e., output from the first output port 111a and the fourth output port 112b, or output from the second output port 111b and the third output port 112a) (i.e., located in diagonal directions relative to each other) have ensured optical coherence with each other. In detail, the first laser beam L1 output from the first output port 111a of the first waveguide 111 and the second laser beam L2 output from the fourth output port 112b of the second waveguide 112 have ensured optical coherence with each other; the first laser beam L1 output from the second output port 111b of the first waveguide 111 and the second laser beam L2 output from the third output port 112a of the second waveguide 112 have ensured optical coherence with each other. Figure 7 The case where the light redirecting device uses the first laser beam L1 output from the first output port 111 a of the first waveguide 111 and the second laser beam L2 output from the fourth output port 112 b of the second waveguide 112 is shown.

[0081] The steering device 202 may steer light in a desired direction by using the first and second laser beams L1 and L2 having optical coherence and output from the tunable laser source 102 , and may include third and fourth waveguides 211 and 212 , splitters 251 and 252 , and modulation units 271 and 272 .

[0082] The third waveguide 211 of the steering device 202 may be connected to the first output port 111a of the first waveguide 111, and the fourth waveguide 212 of the steering device 202 may be connected to the fourth output port 112b of the second waveguide 112. Therefore, the first laser beam L1 output from the first output port 111a of the first waveguide 111 may be incident on the third waveguide 211 of the steering device 202, and the second laser beam L2 output from the fourth output port 112b of the second waveguide 112 may be incident on the fourth waveguide 212 of the steering device 202.

[0083] The phase difference compensation device 151 may be provided on the third waveguide 211. The phase difference compensation device 151 may compensate for the phase difference between the first laser beam L1 and the second laser beam L2 by applying an electrical signal corresponding to the phase difference between the first laser beam L1 and the second laser beam L2 to the third waveguide 211 through which the first laser beam L1 passes. The phase difference compensation device 151 may be provided on the first waveguide 111 of the tunable laser source 100. Alternatively, the phase difference compensation device 151 may be provided on the fourth waveguide 212 of the steering device 202, or provided on both the third waveguide 211 and the fourth waveguide 212 of the steering device 202.

[0084] The first laser beam L1 incident on the third waveguide 211 of the steering device 202 passes through the third waveguide 211 branched by the splitters 251 and 252, and the second laser beam L2 incident on the fourth waveguide 212 of the steering device 202 passes through the fourth waveguide 212 branched by the splitters 251 and 252. The modulation units 271 and 272 may include a first modulation unit 271 provided on the branched third waveguide 211 and a second modulation unit 272 provided on the branched fourth waveguide 212. Each of the first modulation units 271 may independently modulate the phase of the first laser beam L1 passing through one of the third waveguides 211, and each of the second modulation units 272 may independently modulate the phase of the second laser beam L2 passing through one of the fourth waveguides 212.

[0085] The first laser beam L1 and the second laser beam L2 having phases independently modulated by the first modulation unit 271 and the second modulation unit 272 may be output to the outside through the light output portion 290 provided at the ends of the third waveguide 211 and the fourth waveguide 212. The light output portion 290 of the steering device 202 may be arranged on the substrate 50 in the form of a one-dimensional array.

[0086] Figure 7 The light redirecting device is shown as using the first laser beam L1 output from the first output port 111a of the first waveguide 111 and the second laser beam L2 output from the fourth output port 112b of the second waveguide 112. However, the light redirecting device may use the first laser beam L1 output from the second output port 111b of the first waveguide 111 and the second laser beam L2 output from the third output port 112a of the second waveguide 112.

[0087] Figures 8 to 10 Light redirecting devices are shown in which the phase difference compensation device 151 is located at various positions.

[0088] Reference Figure 8, the phase difference compensation device 151 is provided on each of the third waveguides 211 branched by the first splitter 251. The phase difference compensation device 151 can compensate for the phase difference between the first laser beam L1 and the second laser beam L2 by applying an electrical signal corresponding to the phase difference between the first laser beam L1 and the second laser beam L2 to the third waveguide 211 through which the first laser beam L1 passes. The phase difference compensation device 151 can be provided on each of the fourth waveguides 212 branched by the first splitter 251. In this case, the phase difference compensation device 151 can apply an electrical signal corresponding to the phase difference between the first laser beam L1 and the second laser beam L2 to the fourth waveguide 212 through which the second laser beam L2 passes. Alternatively, the phase difference compensation device 151 can be provided on both the third waveguide 211 and the fourth waveguide 212 branched by the first splitter 251.

[0089] Reference Fig. 9 , the phase difference compensation device 151 is provided on each of the third waveguides 211 branched by the second splitter 252. By applying an electrical signal corresponding to the phase difference between the first laser beam L1 and the second laser beam L2 to the third waveguide 211 through which the first laser beam L1 passes, the phase difference compensation device 151 can compensate for the phase difference between the first laser beam L1 and the second laser beam L2. The phase difference compensation device 151 may be provided on each of the fourth waveguides 212 branched by the second splitter 252. In this case, the phase difference compensation device 151 may apply an electrical signal corresponding to the phase difference between the first laser beam L1 and the second laser beam L2 to the fourth waveguide 212 through which the second laser beam L2 passes. Alternatively, the phase difference compensation device 151 may be provided on both the third waveguide 211 and the fourth waveguide 212 branched by the second splitter 252.

[0090] Reference Fig.10 , a plurality of modulation units 273 and 274 can modulate the phases of the first laser beam L1 and the second laser beam L2 and simultaneously compensate for the phase difference between the first laser beam L1 and the second laser beam L2. The modulation units 273 and 274 may include a first modulation unit 273 provided on the branched third waveguide 211 and a second modulation unit 274 provided on the branched fourth waveguide 212.

[0091] For example, the first modulation unit 273 may compensate for the phase difference between the first laser beam L1 and the second laser beam L2. In this case, each of the first modulation units 273 may apply an electrical signal corresponding to the phase difference between the first laser beam L1 and the second laser beam L2 to the third waveguide 211, and simultaneously modulate the phase of the first laser beam L1 passing through the third waveguide 211. Each of the second modulation units 274 may modulate the phase of the second laser beam L2 passing through the fourth waveguide 212. The second modulation unit 274 may compensate for the phase difference between the first laser beam L1 and the second laser beam L2, and both the first modulation unit 273 and the second modulation unit 274 may compensate for the phase difference between the first laser beam L1 and the second laser beam L2.

[0092] According to the above-described example embodiments, when the same amount of power is consumed compared to a case where a single laser beam is used, the light steering device can increase the light output power by simultaneously using two laser beams having optical coherence among the laser beams output from the tunable laser source without losing steering performance. In addition, when the same amount of light output power is achieved, power consumption can be reduced, and the number of elements required to construct the light steering device can be reduced.

[0093] Fig.11 Schematically illustrates an optical system 1000 according to another example embodiment. Fig.11 In the embodiment, the optical system 1000 includes the above-mentioned light redirecting device.

[0094] Reference Fig.11 The system 1000 according to the present example embodiment may include a tunable laser source 1100, a steering device 1200 for steering light in a desired direction, a detection unit 1300 for detecting the steered light, and a driver 1400. The driver 1400 may include a driving circuit for driving the tunable laser source 1100, the steering device 1200, and the detection unit 1300.

[0095] The tunable laser source 1100 may be a laser source that emits light by changing the wavelength of the light to a wide bandwidth. The tunable laser source 1100 may emit a plurality of laser beams, and laser beams having optical coherence with each other among the plurality of laser beams may be incident on the steering device 1200. The tunable laser source 1100 may include the tunable laser sources 100, 101, and 102 described in the above example embodiments.

[0096] The steering device 1200 can steer light in a desired direction by using a plurality of laser beams output from the tunable laser source 1100. The steering device 1200 may include one of the steering devices 200, 201, and 202 described in the above-described example embodiments. When the light steered by the steering device 1200 is irradiated onto an object and reflected from the object, the detection unit 1300 may detect the reflected light. The optical system 1000 may be applied to any of a variety of fields, such as a depth sensor, a 3D sensor, or a light detection and ranging (LiDAR).

[0097] It should be understood that the example embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each example embodiment should typically be considered as available for other similar features or aspects in other example embodiments.

[0098] Although one or more example embodiments have been described with reference to the drawings, people skilled in the art will understand that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims.

[0099] This application claims the benefit of Korean Patent Application No. 10-2018-0070905 filed on June 20, 2018, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A light redirecting device, comprising: A tunable laser source includes a first waveguide and a second waveguide and a first ring resonator and a second ring resonator disposed between the first waveguide and the second waveguide and spaced apart from each other; as well as A steering device, comprising a plurality of modulation units for beam steering; wherein a plurality of optically coherent laser beams output from the tunable laser source are incident on the steering device, wherein the first waveguide includes a first side and a second side, the second waveguide includes a first side adjacent to the first side of the first waveguide and a second side adjacent to the second side of the first waveguide, the first side of the first waveguide and the second side of the second waveguide being located in a diagonal direction relative to each other, and The plurality of optically coherent laser beams include a first laser beam output from the first side of the first waveguide and a second laser beam output from the second side of the second waveguide.

2. The light redirecting device according to claim 1, further comprising: A plurality of input / output connection structures connect the tunable laser source to the steering device, each of the plurality of input / output connection structures corresponding to one of the plurality of optically coherent laser beams.

3. The light redirecting device of claim 1, wherein the tunable laser source further comprises an optical amplifier on at least one of the first waveguide and the second waveguide. 4 . The light redirecting device of claim 1 , wherein each of the first ring resonator and the second ring resonator comprises a ring waveguide and a modulator.

5. The light redirecting device of claim 4, wherein the modulator comprises one of the following: a heating element configured to heat the ring waveguide, an electrode element configured to change a current density of the ring waveguide by applying a current around the ring waveguide, and The piezoelectric element is configured to change the refractive index of the ring waveguide or the refractive index of the material surrounding the ring waveguide according to the application of voltage.

6. The light redirecting device according to claim 1, wherein the tunable laser source further comprises: a first output port at the first side of the first waveguide, a second output port at the second side of the first waveguide, a third output port at the first side of the second waveguide, and a fourth output port at the second side of the second waveguide.

7. The light redirecting device according to claim 1, wherein the redirecting device comprises: a third waveguide connected to the first side of the first waveguide, the first laser beam being incident on the third waveguide; and a fourth waveguide connected to the second side of the second waveguide, the second laser beam being incident on the fourth waveguide.

8. The light redirecting device of claim 7, wherein the first waveguide and the third waveguide are integrally formed, and the second waveguide and the fourth waveguide are integrally formed.

9. The light redirecting apparatus according to claim 7, wherein the redirecting device further comprises a splitter configured to branch the third waveguide into a plurality of third waveguides and a splitter configured to branch the fourth waveguide into a plurality of fourth waveguides. 10 . The light redirecting device according to claim 9 , wherein each of the plurality of modulation units is configured to modulate a phase of a light beam passing through one of the plurality of third waveguides and the plurality of fourth waveguides.

11. The light redirecting device of claim 1, wherein the tunable laser source is configured such that there is a time-independent phase difference between the first laser beam and the second laser beam. 12 . The light redirecting device according to claim 11 , wherein the light redirecting device further comprises a phase difference compensation device configured to compensate for the time-independent phase difference between the first laser beam and the second laser beam.

13. The light steering device according to claim 12, wherein the phase difference compensation device is provided on at least one of the paths of the first laser beam and the second laser beam, and the phase difference compensation device is also configured to apply an electrical signal corresponding to the time-independent phase difference between the first laser beam and the second laser beam. 14 . The light redirecting device of claim 11 , wherein at least one of the plurality of modulation units is configured to apply an electrical signal corresponding to the time-independent phase difference between the first laser beam and the second laser beam.

15. The light redirecting apparatus of claim 1, wherein the redirecting device comprises a plurality of light output portions arranged in a one-dimensional array.

16. An optical system comprising: A tunable laser source includes a first waveguide and a second waveguide and a first ring resonator and a second ring resonator disposed between the first waveguide and the second waveguide and spaced apart from each other; A steering device, comprising a plurality of modulation units for beam steering; as well as a detection unit configured to detect the light beam diverted by the diverting device; wherein a plurality of optically coherent laser beams output from the tunable laser source are incident on the steering device, wherein the first waveguide includes a first side and a second side, the second waveguide includes a first side adjacent to the first side of the first waveguide and a second side adjacent to the second side of the first waveguide, the first side of the first waveguide and the second side of the second waveguide being located in a diagonal direction relative to each other, and The plurality of optically coherent laser beams include a first laser beam output from the first side of the first waveguide and a second laser beam output from the second side of the second waveguide.

17. The optical system of claim 16, wherein the tunable laser source comprises: An optical amplifier is provided on at least one of the first waveguide and the second waveguide.

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