Tunable laser source and light steering device including the same

Abstract

A tunable laser source is provided, comprising: a plurality of optical waveguides; at least three optical resonators disposed between and optically coupled to the plurality of optical waveguides, the at least three optical resonators having different lengths; and at least one optical amplifier disposed on at least one of the plurality of optical waveguides, wherein a ratio of a first length of a first optical resonator of the at least three optical resonators to a second length of a second optical resonator of the at least three optical resonators is not an integer.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Korean Patent Application No. 10-2020-0067314 filed on June 3, 2020, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. Technical Field

[0003] Example embodiments of the present disclosure relate to a tunable laser source and a light steering apparatus including the tunable laser source. Background Art

[0004] In an integrated optical circuit in which optical elements are integrated, a light source is an important component. Light sources can be divided into a single wavelength type and a variable wavelength type (tunable type), and in particular, there is increasing interest in tunable laser sources as light sources for light steering devices such as light detection and ranging (LiDAR) devices. When a single wavelength light source is used as the light source of a light steering device, an antenna array in which antennas are arranged two-dimensionally is required for two-dimensional optical scanning. However, when a tunable light source is used as the light source of a light steering device, an antenna array in which antennas are arranged one-dimensionally can be used for two-dimensional optical scanning. Summary of the Invention

[0005] One or more example embodiments provide a tunable laser source and a light steering apparatus including the tunable laser source.

[0006] Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of example embodiments.

[0007] According to one aspect of example embodiments, there is provided a tunable laser source comprising: a plurality of optical waveguides; at least three optical resonators disposed between and optically coupled to the plurality of optical waveguides, the at least three optical resonators having different lengths; and at least one optical amplifier disposed on at least one of the plurality of optical waveguides, wherein a ratio of a first length of a first optical resonator of the at least three optical resonators to a second length of a second optical resonator of the at least three optical resonators is not an integer.

[0008] The at least three optical resonators may include a first ring resonator having a first circumference, a second ring resonator having a second circumference greater than the first circumference, and a third ring resonator having a third circumference greater than the second circumference.

[0009] The first ratio of the third perimeter to the first perimeter or the second ratio of the third perimeter to the second perimeter may not be an integer.

[0010] The first ratio of the third perimeter to the first perimeter or the second ratio of the third perimeter to the second perimeter may be a rational number having two or more digits after the decimal point.

[0011] A first ratio of the third perimeter to the first perimeter or a second ratio of the third perimeter to the second perimeter may be an irrational number.

[0012] The difference between the first perimeter and the second perimeter may be 1% to 10% of the first perimeter.

[0013] The tunable laser source may further include controllers respectively disposed on the first ring resonator, the second ring resonator, and the third ring resonator, and the controllers are configured to adjust the refractive indexes of the first ring resonator, the second ring resonator, and the third ring resonator, respectively.

[0014] The tunable laser source may further include at least one optical delay line disposed on at least one of the plurality of optical waveguides.

[0015] The tunable laser source may further include at least one optical delay line disposed on at least one of the first ring resonator, the second ring resonator, and the third ring resonator.

[0016] The tunable laser source may further include a fourth ring resonator optically coupled to the third ring resonator, wherein a size of the fourth ring resonator is equal to a size of the third ring resonator.

[0017] The tunable laser source may further include at least one phase shifter disposed on at least one of the plurality of optical waveguides.

[0018] The tunable laser source may further include at least one monitoring device disposed on at least one output port of at least one of the plurality of optical waveguides.

[0019] A tunable laser source can form a closed-loop resonator.

[0020] A tunable laser source can form a Fabry-Perot resonator.

[0021] The tunable laser source may further include grating mirrors or Sagnac mirrors provided at both ends of the Fabry-Perot resonator.

[0022] According to an aspect of another example embodiment, there is provided an optical steering apparatus comprising a tunable laser source and a steering device configured to steer a laser beam incident from the tunable laser source, wherein the tunable laser source comprises: a plurality of optical waveguides; at least three optical resonators disposed between and optically coupled to the plurality of optical waveguides, the at least three optical resonators having different lengths; and at least one optical amplifier disposed on at least one of the plurality of optical waveguides, wherein a ratio of a first length of a first optical resonator of the at least three optical resonators to a second length of a second optical resonator of the at least three optical resonators is not an integer.

[0023] The at least three optical resonators may include a first ring resonator having a first circumference, a second ring resonator having a second circumference greater than the first circumference, and a third ring resonator having a third circumference greater than the second circumference, and a first ratio of the third circumference to the first circumference or a second ratio of the third circumference to the second circumference may not be an integer.

[0024] The tunable laser source may further include at least one monitoring device disposed on at least one output port of at least one of the plurality of optical waveguides.

[0025] The light redirecting apparatus may further comprise a one-dimensional antenna array disposed in the light output portion of the redirecting device.

[0026] The light redirecting apparatus may further include a detector configured to detect the laser beam redirected by the redirecting device.

[0027] According to an aspect of another example embodiment, there is provided a tunable laser source comprising: a plurality of optical waveguides; at least three optical resonators disposed between and optically coupled to the plurality of optical waveguides, the at least three optical resonators having different lengths; and at least one optical amplifier disposed on at least one of the plurality of optical waveguides, wherein a ratio of a first length of a first optical resonator of the at least three optical resonators to a second length of a second optical resonator of the at least three optical resonators is not an integer, and wherein at least one of the at least three optical resonators is disposed on one side of the at least one optical amplifier, and at least two of the at least three optical resonators are disposed on opposite sides of the at least one optical amplifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and / or other aspects, features and advantages of example embodiments will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0029] Figure 1 is a diagram illustrating a tunable laser source according to example embodiments;

[0030] Figure 2A 、 Figure 2B and Figure 2C It shows that according to Figure 1 A diagram showing the optical loss difference versus the circumference ratio of the ring resonator of the tunable laser source;

[0031] Figure 3 shows a tunable laser source according to another example embodiment;

[0032] Figure 4 shows a tunable laser source according to another example embodiment;

[0033] Figure 5 shows a tunable laser source according to another example embodiment;

[0034] Figure 6 shows a tunable laser source according to another example embodiment;

[0035] Figure 7 shows a tunable laser source according to another example embodiment;

[0036] Figure 8 shows a tunable laser source according to another example embodiment;

[0037] Figure 9 shows a tunable laser source according to another example embodiment;

[0038] Figure 10 shows a tunable laser source according to another example embodiment;

[0039] Figure 11 shows a tunable laser source according to another example embodiment; and

[0040] Figure 12 A light redirecting device according to an example embodiment is shown. DETAILED DESCRIPTION

[0041] With reference now to embodiment in detail, examples of embodiments are shown in the accompanying drawings, wherein similar reference numerals throughout the accompanying drawings represent similar elements. In this regard, example embodiments may have different forms and should not be construed as being limited to the description set forth herein. Therefore, example embodiments are described below only with reference to the accompanying drawings to explain various aspects. As used herein, the term "and / or" includes any and all combinations of one or more of the items listed in the association. Statements such as "at least one of..." modify the entire list of elements when following a list of elements, rather than modifying the individual elements in the list. For example, the statement "at least one of a, b, and c" should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0042] Hereinafter, example embodiments will be described with reference to the accompanying drawings. In the accompanying drawings, the size of elements may be exaggerated for clarity of illustration. The example embodiments described herein are for illustrative purposes only and various modifications may be made therein.

[0043] In the following description, when an element is referred to as being "on" or "upper" another element, it may be directly on the upper, lower, left, or right side of the other element while contacting the other element, or it may be on the upper, lower, left, or right side of the other element without contacting the other element. Unless otherwise mentioned, terms in the singular may include plural forms. It will also be understood that the terms "include" and / or "comprising" used herein specify the presence of the described features or elements, but do not exclude the presence or addition of one or more other features or elements.

[0044] An element referred to with a definite article or demonstrative pronoun may be construed as referring to one or more elements even if it is in the singular. Unless explicitly described or otherwise described in terms of order, the operations of the method may be performed in a suitable order and are not limited to the order described.

[0045] In the present disclosure, terms such as “unit” or “module” may be used to indicate a unit having at least one function or operation and implemented by hardware, software, or a combination of hardware and software.

[0046] Furthermore, the line connections or connecting members between the elements depicted in the drawings represent functional connections and / or physical or circuit connections by way of example, and in actual applications, they may be replaced or implemented by various other functional connections, physical connections or circuit connections.

[0047] Examples or exemplary terms are used herein only to describe technical ideas and should not be considered for limiting purposes unless defined by the claims.

[0048] Figure 1 A tunable laser source 100 is shown according to an example embodiment. Figure 1 A tunable laser source 100 of on-chip type is shown, wherein all components are integrated on a substrate 110. The tunable laser source 100 may be, for example, a tunable laser diode.

[0049] Figure 1 The tunable laser source 100 shown may generally form a closed-loop resonator. Figure 1 The tunable laser source 100 may include: a plurality of optical waveguides 111 , 112 and 113 , three or more optical resonators R1 , R2 and R3 arranged between the optical waveguides 111 , 112 and 113 , and one or more optical amplifiers 121 and 122 provided on the optical waveguides 111 , 112 and 113 .

[0050] Optical waveguides 111, 112, and 113, three or more optical resonators R1, R2, and R3, and one or more optical amplifiers 121 and 122 may be integrated on a substrate 110 through a semiconductor process. Here, the substrate 110 may be a semiconductor substrate such as a silicon substrate, but is not limited thereto.

[0051] The optical waveguides 111, 112, and 113 may include a first optical waveguide 111, a second optical waveguide 112, and a third optical waveguide 113 that are separated from each other. The first optical waveguide 111, the second optical waveguide 112, and the third optical waveguide 113 may be arranged side by side, but are not limited thereto. The first optical waveguide 111, the second optical waveguide 112, and the third optical waveguide 113 may include, for example, silicon. However, this is merely an example, and the first optical waveguide 111, the second optical waveguide 112, and the third optical waveguide 113 may include various other materials.

[0052] The three or more optical resonators R1, R2, and R3 may include a first ring resonator R1, a second ring resonator R2, and a third ring resonator R3. For example, the first ring resonator R1 may be arranged between the first optical waveguide 111 and the second optical waveguide 112. Here, the first ring resonator R1 may be physically separated from the first optical waveguide 111 and the second optical waveguide 112, but may be optically coupled to the first optical waveguide 111 and the second optical waveguide 112. The first ring resonator R1 may be physically separated from the first optical waveguide 111 and the second optical waveguide 112 by approximately 0.1 μm to approximately 1 μm, but the embodiment is not limited thereto.

[0053] The second ring resonator R2 may be disposed between the second optical waveguide 112 and the third optical waveguide 113. Here, the second ring resonator R2 may be physically separated from the second optical waveguide 112 and the third optical waveguide 113, but may be optically coupled with the second optical waveguide 112 and the third optical waveguide 113. The second ring resonator R2 may be physically separated from the second optical waveguide 112 and the third optical waveguide 113 by approximately 0.1 μm to approximately 1 μm, but the embodiment is not limited thereto.

[0054] The third ring resonator R3 may be disposed between the first optical waveguide 111 and the third optical waveguide 113. Here, the third ring resonator R3 may be physically separated from the first optical waveguide 111 and the third optical waveguide 113, but may be optically coupled with the first optical waveguide 111 and the third optical waveguide 113. The third ring resonator R3 may be physically separated from the first optical waveguide 111 and the third optical waveguide 113 by approximately 0.1 μm to approximately 1 μm, but the embodiment is not limited thereto.

[0055] Each of the first ring resonator R1, the second ring resonator R2, and the third ring resonator R3 may have a circular shape or various other ring shapes. The first ring resonator R1, the second ring resonator R2, and the third ring resonator R3 may have different lengths, for example, different circumferences. For example, the first ring resonator R1 may have a first circumference L1, the second ring resonator R2 may have a second circumference L2 greater than the first circumference L1, and the third ring resonator R3 may have a third circumference L3 greater than the second circumference L2. For example, each of the first ring resonator R1, the second ring resonator R2, and the third ring resonator R3 may have a circumference of approximately tens of micrometers (μm) or approximately hundreds of micrometers (μm). However, the embodiment is not limited thereto, and each of the first ring resonator R1, the second ring resonator R2, and the third ring resonator R3 may have various other circumferences.

[0056] The difference between the first perimeter L1 and the second perimeter L2 may depend on the variable wavelength range. For example, the difference between the first perimeter L1 and the second perimeter L2 may be approximately 1% to approximately 10% of the first perimeter L1. However, embodiments are not limited thereto. In addition, as described later, when the ratio L3 / L1 of the third perimeter L3 to the first perimeter L1 or the ratio L3 / L2 of the third perimeter L3 to the second perimeter L2 is designed to be a number other than an integer, mode selectivity can be improved.

[0057] Controllers 151, 152, and 153 may be disposed near the first ring resonator R1, the second ring resonator R2, and the third ring resonator R3, respectively, to adjust the refractive indexes of the first ring resonator R1, the second ring resonator R2, and the third ring resonator R3. For example, a first controller 151 configured to adjust the refractive index of the first ring resonator R1 may be disposed near the first ring resonator R1, a second controller 152 configured to adjust the refractive index of the second ring resonator R2 may be disposed near the second ring resonator R2, and a third controller 153 configured to adjust the refractive index of the third ring resonator R3 may be disposed near the third ring resonator R3. Figure 1 In the example shown, the controllers 151, 152, and 153 are disposed inside the ring resonators R1, R2, and R3. However, the embodiment is not limited thereto, and the positions of the controllers 151, 152, and 153 may be variously modified.

[0058] The first controller 151, the second controller 152 and the third controller 153 can respectively control the refractive index of the first ring resonator R1, the second ring resonator R2 and the third ring resonator R3, so that the resonant wavelength comb of each of the first ring resonator R1, the second ring resonator R2 and the third ring resonator R3 can be horizontally moved along the wavelength axis to achieve variable wavelength, as described later.

[0059] For example, the controllers 151, 152 and 153 may respectively include: a heating element configured to change the refractive index of the ring resonators R1, R2 and R3 by heating the ring resonators R1, R2 and R3; an electrode element configured to change the refractive index of the ring resonators R1, R2 and R3 by applying an electric field around the ring resonators R1, R2 and R3; or a piezoelectric element configured to change the refractive index of the ring resonators R1, R2 and R3 by deforming the ring resonators R1, R2 and R3.

[0060] The one or more optical amplifiers 121 and 122 may include a first optical amplifier 121 and a second optical amplifier 122 provided on the optical waveguides 111, 112, and 113. Figure 1 In the illustrated example, the first optical amplifier 121 is disposed on the first optical waveguide 111, and the second optical amplifier 122 is disposed on the third optical waveguide 113. However, embodiments are not limited thereto, and the number and positions of the optical amplifiers may be determined differently. The first and second ring resonators R1 and R2 may be disposed on one side of the first and second optical amplifiers 121 and 122, and the third ring resonator R3 may be disposed on the other side of the first and second optical amplifiers 121 and 122.

[0061] The first optical amplifier 121 and the second optical amplifier 122 can be configured to amplify light and also to generate light. Each of the first optical amplifier 121 and the second optical amplifier 122 can include, for example, a semiconductor optical amplifier. For example, a semiconductor optical amplifier can be formed by depositing a material layer including a Group III-V semiconductor or a Group II-VI semiconductor on an optical waveguide including silicon. However, embodiments are not limited thereto, and each of the first optical amplifier 121 and the second optical amplifier 122 can include an ion-doped amplifier.

[0062] The light generated by at least one of the first optical amplifier 121 and the second optical amplifier 122 may be Figure 1 The light propagating clockwise or counterclockwise through the first ring resonator R1 , the second ring resonator R2 , and the third ring resonator R3 in the closed-loop resonator shown is amplified and can then be output at a desired resonance wavelength. Figure 1 An example is shown in which the amplified laser beam L is output to the outside through the main output port of the first optical waveguide 111 .

[0063] Typically, a ring resonator has a resonant wavelength comb consisting of resonant wavelengths arranged at intervals determined by the ring resonator's circumference. When multiple ring resonators with different circumferences are combined, multiple resonant wavelength combs with different intervals are generated. Within these resonant wavelength combs, only the first oscillation mode in which the first resonant wavelength is arranged can be selected to oscillate a single-mode laser beam. Furthermore, by adjusting the refractive index of at least one ring resonator, at least one resonant wavelength comb can be horizontally shifted along the wavelength axis. This allows a second oscillation mode in which the second resonant wavelength is arranged to be selected in place of the first oscillation mode, thus realizing a tunable laser source.

[0064] In tunable laser sources, high mode selectivity is required for stable single-mode oscillation. Mode selectivity can be determined by the optical gain difference or optical loss difference between the most favorable oscillation mode and the competing mode, which is the second most favorable oscillation mode. Assuming that the optical gain is independent of wavelength, mode selectivity can be determined by the optical loss difference between the oscillation mode and the competing mode.

[0065] In the oscillation mode, all resonant wavelengths are aligned, while in the competition mode, at least some resonant wavelengths are misaligned. Therefore, a light loss difference occurs between the oscillation mode and the competition mode, and as the light loss difference increases, mode selectivity may increase.

[0066] The mode selectivity of the tunable laser source 100 of the example embodiment may be improved by adjusting the first circumference L1 of the first ring resonator R1 , the second circumference L2 of the second ring resonator R2 , and the third circumference L3 of the third ring resonator R3 .

[0067] As described above, the first ring resonator R1, the second ring resonator R2, and the third ring resonator R3 may have a first circumference L1, a second circumference L2, and a third circumference L3, respectively. Here, when a ratio L3 / L1 of the third circumference L3 of the third ring resonator R3 to the first circumference L1 of the first ring resonator R1 or a ratio L3 / L2 of the third circumference L3 of the third ring resonator R3 to the second circumference L2 of the second ring resonator R2 is designed to be a number other than an integer, the mode selectivity of the tunable laser source 100 may be improved, as described later.

[0068] Figures 2A to 2C It shows that according to Figure 1 FIG. 1 is a graph showing the optical loss difference of the circumference ratio of the ring resonators R1, R2 and R3 of the tunable laser source 100. Figures 2A to 2C In the illustrated example, a difference between a first perimeter L1 of the first ring resonator R1 and a second perimeter L2 of the second ring resonator R2 is 1% to 10% of the first perimeter L1 .

[0069] Figure 2A The wavelength combs of the first, second, and third ring resonators R1, R2, and R3, and the wavelength comb of the combination of the first, second, and third ring resonators R1, R2, and R3 are shown when the third circumference L3 of the third ring resonator R3 is twice the first circumference L1 of the first ring resonator R1, wherein a ratio L3 / L1 of the third circumference L3 to the first circumference L1 is 2.

[0070] Figure 2B The wavelength combs of the first, second, and third ring resonators R1, R2, and R3, and the wavelength comb of the combination of the first, second, and third ring resonators R1, R2, and R3 are shown when the third circumference L3 of the third ring resonator R3 is three times the first circumference L1 of the first ring resonator R1, wherein a ratio L3 / L1 of the third circumference L3 to the first circumference L1 is 3.

[0071] Figure 2C The wavelength combs of the first, second, and third ring resonators R1, R2, and R3, and the wavelength comb of the combination of the first, second, and third ring resonators R1, R2, and R3 are shown when the third circumference L3 of the third ring resonator R3 is 2.5 times the first circumference L1 of the first ring resonator R1, wherein a ratio L3 / L1 of the third circumference L3 to the first circumference L1 is 2.5.

[0072] refer to Figures 2A to 2C, the optical loss difference ΔH3 between the oscillation mode and the competition mode when the ratio L3 / L1 of the third perimeter L3 to the first perimeter L1 is 2.5 is greater than the optical loss difference ΔH1 when the ratio L3 / L1 of the third perimeter L3 to the first perimeter L1 is 2 and the optical loss difference ΔH2 when the ratio L3 / L1 of the third perimeter L3 to the first perimeter L1 is 3.

[0073] In simulations, the optical loss difference was measured while varying the ratio (L3 / L1) of the third perimeter L3 of the third ring resonator R3 to the first perimeter L1 of the first ring resonator R1. In the simulations, the difference between the first perimeter L1 of the first ring resonator R1 and the second perimeter L2 of the second ring resonator R2 was set to 1% to 10% of the first perimeter L1.

[0074] When only the first and second ring resonators R1 and R2 are combined, the optical loss difference between the oscillation mode and the competition mode is measured to be as low as about 11 dB to about 14 dB, indicating that the mode selectivity may be relatively low when only two ring resonators are used.

[0075] When the ratio L3 / L1 of the third perimeter L3 to the first perimeter L1 is set to 2 and 3, the optical loss difference between the oscillation mode and the competition mode is measured to be about 12 dB to about 16 dB. This indicates that when the ratio L3 / L1 of the third perimeter L3 to the first perimeter L1 is set to an integer in the tunable laser source 100 including the three ring resonators R1, R2, and R3, the mode selectivity of the tunable laser source 100 can be as low as that in the case of using only two ring resonators.

[0076] When the ratio L3 / L1 of the third perimeter L3 to the first perimeter L1 is set to 2.5, the optical loss difference between the oscillation mode and the competition mode is measured to be about 16 dB to about 20 dB. This indicates that when the ratio L3 / L1 of the third perimeter L3 to the first perimeter L1 is set to a non-integer in the tunable laser source 100 including the three ring resonators R1, R2, and R3, the mode selectivity of the tunable laser source 100 can be improved compared to the case where the ratio L3 / L1 is an integer.

[0077] When the ratio L3 / L1 of the third perimeter L3 to the first perimeter L1 was set to 2.25 and 2.75, the optical loss difference between the oscillation mode and the competition mode was measured to be approximately 24 dB to approximately 28 dB. When the ratio L3 / L1 of the third perimeter L3 to the first perimeter L1 was set to 2.225 and 2.275, the optical loss difference between the oscillation mode and the competition mode was measured to be approximately 32 dB to approximately 37 dB.

[0078] These results indicate that when the ratio L3 / L1 of the third circumference L3 to the first circumference L1 of the tunable laser source 100 including the three ring resonators R1, R2, and R3 is set to a rational number with two or more digits after the decimal point, the mode selectivity of the tunable laser source 100 is further improved. Furthermore, these results indicate that the mode selectivity improves as the number of digits after the decimal point increases. Therefore, when the ratio L3 / L1 of the third circumference L3 to the first circumference L1 of the tunable laser source 100 including the three ring resonators R1, R2, and R3 is set to an irrational number, the tunable laser source 100 can have improved mode selectivity.

[0079] Although the above description is given only with respect to the ratio L3 / L1 of the third circumference L3 of the third ring resonator R3 to the first circumference L1 of the first ring resonator R1, the above description can be applied to the ratio L3 / L2 of the third circumference L3 of the third ring resonator R3 to the second circumference L2 of the second ring resonator R2. For example, when the ratio L3 / L2 of the third circumference L3 of the third ring resonator R3 to the second circumference L2 of the second ring resonator R2 is designed to be a non-integer, mode selectivity can be improved.

[0080] A tunable laser source used in a light steering device such as a light detection and ranging (LiDAR) device can have a large coherence length when the spectral linewidth in the oscillation mode of the tunable laser source is small. In this case, the tunable laser source may be able to perform long-distance detection. Because the spectral linewidth in the oscillation mode of a resonator is approximately inversely proportional to the square of the total length of the resonator, the spectral linewidth decreases as the total length of the resonator increases.

[0081] The tunable laser source 100 of example embodiments may include one or more optical delay lines 130 disposed on the optical waveguides 111 , 112 , and 113 to reduce a spectral linewidth in an oscillation mode. Figure 1 An example is shown in which one optical delay line 130 is provided on the first optical waveguide 111. However, the embodiment is not limited thereto, and the number and position of the optical delay lines 130 may be determined differently. The optical delay line 130 may have the function of reducing the spectral linewidth in the oscillation mode by increasing the total length of the entire resonator as a closed-loop resonator. The optical delay line 130 may include, for example, a spiral waveguide.

[0082] The tunable laser source 100 may further include one or more phase shifters 140 provided on the optical waveguides 111, 112, and 113. In this case, when the phase of the entire resonator as a closed-loop resonator is different from the phase of the ring resonators R1, R2, and R3, the phase shifter 140 may compensate for the phase difference. Figure 1An example is shown in which one phase shifter 140 is provided on the third optical waveguide 113 , but the number and positions of the phase shifters 140 may be variously determined.

[0083] As described above, the tunable laser source 100 of the example embodiment includes three ring resonators having different circumferences, for example, the first ring resonator R1, the second ring resonator R2, and the third ring resonator R3, and a ratio L3 / L1 of a third circumference L3 of the third ring resonator R3 to a first circumference L1 of the first ring resonator R1 or a ratio L3 / L2 of a third circumference L3 of the third ring resonator R3 to a second circumference L2 of the second ring resonator R2 may be adjusted to a non-integer to improve the mode selectivity of the tunable laser source 100 and thereby achieve a stable single oscillation mode.

[0084] Furthermore, the total length of the entire resonator can be increased by providing one or more optical delay lines 130 on the optical waveguides 111, 112, and 113, and thus the spectral linewidth in the oscillation mode can be reduced. Furthermore, all components of the tunable laser source 100 can be integrated on a single substrate (e.g., substrate 110), and thus the tunable laser source 100 can be implemented as an on-chip device.

[0085] Figure 3 FIG. 2 shows a tunable laser source 200 according to another example embodiment. In addition to the position of the optical delay line 230, Figure 3 The tunable laser source 200 is shown with Figure 1 The tunable laser sources 100 shown are identical.

[0086] refer to Figure 3 The tunable laser source 200 may include one or more optical delay lines 230 disposed in a plurality of ring resonators R1, R2, and R3 including a first ring resonator R1, a second ring resonator R2, and a third ring resonator R3. Here, the optical delay line 230 may include, for example, a spiral waveguide. Figure 3 An example is shown in which one optical delay line 230 is provided in the third ring resonator R3. However, the embodiment is not limited thereto, and the optical delay line 230 may be provided in the first ring resonator R1 or the second ring resonator R2. In addition, the number and position of the optical delay line 230 may be determined differently.

[0087] Even when the optical delay line 230 provided in the ring resonators R1, R2, and R3 of the tunable laser source 200 is larger than that provided in the ring resonators R1, R2, and R3 of the tunable laser source 200, Figure 1When the optical delay line 130 on the optical waveguides 111, 112, and 113 of the tunable laser source 100 is short, the spectral linewidth in the oscillation mode of the tunable laser source 200 can also be reduced as much as the spectral linewidth in the oscillation mode of the tunable laser source 100. Therefore, the tunable laser source 200 can have a shorter optical power than that of the tunable laser source 100. Figure 1 The tunable laser source 100 is shown in a smaller size.

[0088] Figure 4 FIG. 3 shows a tunable laser source 300 according to another example embodiment. In addition to the monitoring devices 171 to 175, Figure 4 The tunable laser source 300 shown is Figure 1 The tunable laser sources 100 shown are identical.

[0089] refer to Figure 4 , the tunable laser source 300 may include one or more monitoring devices, which include a first monitoring device 171, a second monitoring device 172, a third monitoring device 173, a fourth monitoring device 174, and a fifth monitoring device 175. In this case, the one or more monitoring devices 171 to 175 may be provided on the auxiliary output ports of the plurality of optical waveguides 111, 112, and 113 in addition to the main output ports of the optical waveguides 111, 112, and 113 through which the amplified laser beam L is output. The one or more monitoring devices 171 to 175 may measure the amount of light output from the auxiliary output ports of the optical waveguides 111, 112, and 113 to monitor the wavelength alignment between the first ring resonator R1, the second ring resonator R2, and the third ring resonator R3. Although Figure 4 An example is shown in which five monitoring devices 171 to 175 are provided, but the embodiment is not limited thereto, and the number of monitoring devices 171 to 175 may be variously determined.

[0090] exist Figure 4 In the embodiment, one end of the first optical waveguide 111, both ends of the second optical waveguide 112, and both ends of the third optical waveguide 113 may correspond to auxiliary output ports. In addition, the other end of the first optical waveguide 111 may correspond to a main output port through which the amplified laser beam L is output.

[0091] The first monitoring device 171 and the second monitoring device 172 may be provided at both ends of the third optical waveguide 113, and the third monitoring device 173 and the fourth monitoring device 174 may be provided at both ends of the second optical waveguide 112. In addition, the fifth monitoring device 175 may be provided at one end of the first optical waveguide 111. Each of the first to fifth monitoring devices 171 to 175 may include, for example, a photodiode.

[0092] The first monitoring device 171 and the second monitoring device 172 can monitor the wavelength alignment between the second ring resonator R2 and the third ring resonator R3, and the third monitoring device 173 and the fourth monitoring device 174 can monitor the wavelength alignment between the first ring resonator R1 and the second ring resonator R2. In addition, the fifth monitoring device 175 can monitor the wavelength alignment between the first ring resonator R1 and the third ring resonator R3.

[0093] As described above, since the monitoring devices 171 to 175 are provided on the auxiliary output ports of the optical waveguides 111 , 112 , and 113 to monitor the wavelength alignment between the ring resonators R1 , R2 , and R3 , on-chip control is possible.

[0094] The tunable laser source 300 may include one or more optical delay lines 130 disposed on optical waveguides 111 , 112 , and 113 .

[0095] Figure 5 A tunable laser source 400 according to another example embodiment is shown. In addition to the position of the optical delay line 230, Figure 5 The tunable laser source 400 is shown with Figure 4 The tunable laser source 300 shown is the same as that shown in FIG. Figure 5 , the tunable laser source 400 may include one or more optical delay lines 230 disposed in a plurality of ring resonators R1 , R2 , and R3 .

[0096] Figure 6 A tunable laser source 500 according to another example embodiment is shown. Figure 6 The illustrated tunable laser source 500 may generally form a closed-loop resonator.

[0097] refer to Figure 6 The first optical waveguide 511, the second optical waveguide 512 and the third optical waveguide 513 are arranged separately from each other, and four ring resonators, for example, the first ring resonator R1, the second ring resonator R2, the third ring resonator R3 and the fourth ring resonator R4, are arranged between the first optical waveguide 511, the second optical waveguide 512 and the third optical waveguide 513.

[0098] The first ring resonator R1 may be disposed between the first optical waveguide 511 and the second optical waveguide 512, and the second ring resonator R2 may be disposed between the second optical waveguide 512 and the third optical waveguide 513. Here, the first ring resonator R1 and the second ring resonator R2 may be physically separated from the first optical waveguide 511, the second optical waveguide 512, and the third optical waveguide 513, but may be optically coupled with the first optical waveguide 511, the second optical waveguide 512, and the third optical waveguide 513.

[0099] The third ring resonator R3 may be disposed between the first optical waveguide 511 and the third optical waveguide 513. Here, the third ring resonator R3 may be physically separated from the first optical waveguide 511 and the third optical waveguide 513 but may be optically coupled with the first optical waveguide 511 and the third optical waveguide 513.

[0100] The fourth ring resonator R4 may be arranged adjacent to the third ring resonator R3 between the first optical waveguide 511 and the third optical waveguide 513. Here, the fourth ring resonator R4 may be physically separated from the third ring resonator R3 but may be optically coupled to the third ring resonator R3. Furthermore, the fourth ring resonator R4 may be physically and optically separated from the first optical waveguide 511 and the third optical waveguide 513.

[0101] In this example embodiment, similar to the optical delay lines 130 and 230 described above, the fourth ring resonator R4 can function to reduce the spectral linewidth by increasing the total length of the entire resonator as a closed-loop resonator. The fourth ring resonator R4 can have the same size and resonant wavelength as the third ring resonator R3. Therefore, light resonating in the third ring resonator R3 can resonate in the fourth ring resonator R4, thereby increasing the total length of the entire resonator and reducing the spectral linewidth of the laser beam output from the tunable laser source 500.

[0102] The first ring resonator R1, the second ring resonator R2, and the third ring resonator R3 may have different circumferences from each other. For example, the first ring resonator R1 may have a first circumference L1, the second ring resonator R2 may have a second circumference L2 greater than the first circumference L1, and the third ring resonator R3 may have a third circumference L3 greater than the second circumference L2.

[0103] The difference between the first perimeter L1 and the second perimeter L2 may be about 1% to about 10% of the first perimeter L1, but the embodiment is not limited thereto. In addition, when the ratio L3 / L1 of the third perimeter L3 to the first perimeter L1 or the ratio L3 / L2 of the third perimeter L3 to the second perimeter L2 is designed to be a number other than an integer, the mode selectivity may be improved.

[0104] A first controller 551, a second controller 552, a third controller 553, and a fourth controller 554 may be provided near the first ring resonator R1, the second ring resonator R2, the third ring resonator R3, and the fourth ring resonator R4 to adjust the refractive index of the first ring resonator R1, the second ring resonator R2, the third ring resonator R3, and the fourth ring resonator R4. Here, each of the controllers 551, 552, 553, and 554 may include, for example, a heating element, an electrode element, or a piezoelectric element.

[0105] One or more optical amplifiers 521 and 522 may be provided on the first optical waveguide 511, the second optical waveguide 512, and the third optical waveguide 513. Figure 6 In the illustrated example, a first optical amplifier 521 is provided on the first optical waveguide 511, and a second optical amplifier 522 is provided on the third optical waveguide 513. Here, the first ring resonator R1 and the second ring resonator R2 may be provided on one side of the first optical amplifier 521 and the second optical amplifier 522, and the third ring resonator R3 and the fourth ring resonator R4 may be provided on the other side of the first optical amplifier 521 and the second optical amplifier 522.

[0106] At least one phase shifter 540 may be further provided on the first optical waveguide 511 , the second optical waveguide 512 , and the third optical waveguide 513 . Figure 6 An example is shown in which one phase shifter 540 is provided on the third optical waveguide 513 , but the embodiment is not limited thereto, and the number and positions of the phase shifters 540 may be variously determined.

[0107] Figure 7 A tunable laser source 600 according to another example embodiment is shown. In addition to the monitoring devices 571 to 575, Figure 7 The tunable laser source 600 shown is Figure 6 The tunable laser sources 500 shown are identical.

[0108] refer to Figure 7 One or more monitoring devices, such as a first monitoring device 571, a second monitoring device 572, a third monitoring device 573, a fourth monitoring device 574, and a fifth monitoring device 575, may be provided on the first optical waveguide 511, the second optical waveguide 512, and the third optical waveguide 513. For example, one or more monitoring devices 571 to 575 may be provided on auxiliary output ports of the first optical waveguide 511, the second optical waveguide 512, and the third optical waveguide 513.

[0109] A first monitoring device 571 and a second monitoring device 572 may be provided at both ends of the third optical waveguide 513 to monitor the wavelength alignment between the second ring resonator R2 and the third ring resonator R3. A third monitoring device 573 and a fourth monitoring device 574 may be provided at both ends of the second optical waveguide 512 to monitor the wavelength alignment between the first ring resonator R1 and the second ring resonator R2. In addition, a fifth monitoring device 575 may be provided at one end of the first optical waveguide 511 to monitor the wavelength alignment between the first ring resonator R1 and the third ring resonator R3.

[0110] Figure 8 A tunable laser source 700 is shown according to another example embodiment. Figure 8The illustrated tunable laser source 700 may generally form a Fabry-Perot resonator.

[0111] refer to Figure 8 The first optical waveguide 711, the second optical waveguide 712, the third optical waveguide 713 and the fourth optical waveguide 714 are arranged to be spaced apart from each other, and the first ring resonator R1, the second ring resonator R2 and the third ring resonator R3 are arranged between the first optical waveguide 711, the second optical waveguide 712, the third optical waveguide 713 and the fourth optical waveguide 714.

[0112] The first ring resonator R1 may be disposed between the first optical waveguide 711 and the second optical waveguide 712, the second ring resonator R2 may be disposed between the second optical waveguide 712 and the third optical waveguide 713, and the third ring resonator R3 may be disposed between the third optical waveguide 713 and the fourth optical waveguide 714. Here, the first ring resonator R1, the second ring resonator R2, and the third ring resonator R3 may be physically separated from the first optical waveguide 711, the second optical waveguide 712, the third optical waveguide 713, and the fourth optical waveguide 714, but may be optically coupled with the first optical waveguide 711, the second optical waveguide 712, the third optical waveguide 713, and the fourth optical waveguide 714. For example, the first to third ring resonators R1 , R2 , and R3 may be physically separated from the first to fourth optical waveguides 711 , 712 , 713 , and 714 by about 0.1 μm to about 1 μm, but the embodiment is not limited thereto.

[0113] The first ring resonator R1, the second ring resonator R2, and the third ring resonator R3 may have different circumferences from each other. For example, the first ring resonator R1 may have a first circumference L1, the second ring resonator R2 may have a second circumference L2 greater than the first circumference L1, and the third ring resonator R3 may have a third circumference L3 greater than the second circumference L2.

[0114] The difference between the first perimeter L1 and the second perimeter L2 may be approximately 1% to approximately 10% of the first perimeter L1, but the embodiment is not limited thereto. Furthermore, when the ratio L3 / L1 of the third perimeter L3 to the first perimeter L1 or the ratio L3 / L2 of the third perimeter L3 to the second perimeter L2 is designed to be a number other than an integer, mode selectivity may be improved. The first control section 751, the second control section 752, and the third control section 753 may be disposed near the first ring resonator R1, the second ring resonator R2, and the third ring resonator R3 to adjust the refractive index of the first ring resonator R1, the second ring resonator R2, and the third ring resonator R3.

[0115] One or more optical amplifiers 720 may be disposed on the first optical waveguide 711 , the second optical waveguide 712 , the third optical waveguide 713 , and the fourth optical waveguide 714 . Figure 8 An example is shown in which one optical amplifier 720 is provided on the first optical waveguide 711. Here, the first ring resonator R1, the second ring resonator R2, and the third ring resonator R3 may be provided on one side of the optical amplifier 720.

[0116] At least one optical delay line 730 may be disposed on the first optical waveguide 711 , the second optical waveguide 712 , the third optical waveguide 713 , and the fourth optical waveguide 714 . Figure 8 The figure shows an example in which an optical delay line 730 is provided on a first optical waveguide 711. The optical delay line 730 can reduce the spectral linewidth in an oscillation mode by increasing the total length of the entire resonator, which functions as a Fabry-Perot resonator. The optical delay line 730 can include, for example, a spiral waveguide. At least one phase shifter 740 can also be provided on the first optical waveguide 711, the second optical waveguide 712, the third optical waveguide 713, and the fourth optical waveguide 714. Figure 8 An example is shown in which one phase shifter 740 is provided on the first optical waveguide 711 .

[0117] The first grating mirror 781 and the second grating mirror 782 can be arranged at both ends of the entire resonator as a Fabry-Perot resonator. For example, the first grating mirror 781 can be arranged at one end of the first optical waveguide 711, and the second grating mirror 782 can be arranged at one end of the fourth optical waveguide 714. Each of the first grating mirror 781 and the second grating mirror 782 can be a highly reflective mirror on which a grating pattern is periodically arranged at predetermined intervals. Here, the period of the grating pattern can be related to the wavelength of light propagating in the first optical waveguide 711, the second optical waveguide 712, the third optical waveguide 713, and the fourth optical waveguide 714, and can be, for example, about 100 nm to about 500 nm. However, the embodiment is not limited thereto.

[0118] Light generated by the optical amplifier 720 may be amplified while reciprocating between the first grating mirror 781 and the second grating mirror 782 through the first ring resonator R1 , the second ring resonator R2 , and the third ring resonator R3 , and may then be output at a desired resonance wavelength. Figure 8 An example is shown in which the amplified laser beam L is output to the outside through the main output port of the fourth optical waveguide 714 .

[0119] The tunable laser source 700 of the example embodiment includes three ring resonators having different circumferences, for example, a first ring resonator R1, a second ring resonator R2, and a third ring resonator R3, and a ratio L3 / L1 of a third circumference L3 of the third ring resonator R3 to a first circumference L1 of the first ring resonator R1 or a ratio L3 / L2 of the third circumference L3 of the third ring resonator R3 to a second circumference L2 of the second ring resonator R2 can be adjusted to a non-integer to improve mode selectivity and thereby achieve a stable single oscillation mode.

[0120] Furthermore, the total length of the entire resonator can be increased based on one or more optical delay lines 730 provided on the first optical waveguide 711, the second optical waveguide 712, the third optical waveguide 713, and the fourth optical waveguide 714, thereby reducing the spectral linewidth in the oscillation mode. Furthermore, all components of the tunable laser source 700 can be integrated on a single substrate (e.g., the substrate 110), and thus the tunable laser source 700 can be implemented as an on-chip device.

[0121] The above description gives the case where the first grating mirror 781 and the second grating mirror 782 are respectively provided at both ends of the Fabry-Perot resonator. However, the embodiment is not limited thereto. For example, a Sagnac mirror may be provided at both ends of the Fabry-Perot resonator.

[0122] Figure 9 A tunable laser source 800 according to another example embodiment is shown. In addition to the position of the optical delay line 830, Figure 9 The tunable laser source 800 shown is Figure 8 The tunable laser sources 700 shown are identical.

[0123] refer to Figure 9 At least one optical delay line 830 may be provided in the plurality of ring resonators R1 , R2 , and R3 including the first ring resonator R1 , the second ring resonator R2 , and the third ring resonator R3 . Figure 9 FIG. 8 shows an example in which an optical delay line 830 is provided in the third ring resonator R3. Therefore, the tunable laser source 800 can be smaller than Figure 8 A tunable laser source 700 is shown.

[0124] Figure 10 A tunable laser source 900 according to another example embodiment is shown. In addition to monitoring devices 971 to 977, Figure 10 The tunable laser source 900 shown is Figure 8 The tunable laser sources 700 shown are identical.

[0125] refer to Figure 10The tunable laser source 900 may include one or more monitoring devices, for example, a first monitoring device 971, a second monitoring device 972, a third monitoring device 973, a fourth monitoring device 974, a fifth monitoring device 975, a sixth monitoring device 976, and a seventh monitoring device 977. In this case, the one or more monitoring devices 971 to 977 may be provided at auxiliary output ports of the plurality of optical waveguides 711, 712, 713, and 714 in addition to main output ports of the optical waveguides 711, 712, 713, and 714 through which the amplified laser beam L is output. Figure 10 An example is shown in which the first to seventh monitoring devices 971 to 977 are provided on the auxiliary output ports of the first optical waveguide 711 , the second optical waveguide 712 , the third optical waveguide 713 , and the fourth optical waveguide 714 .

[0126] exist Figure 10 , one end of the fourth optical waveguide 714 may correspond to a main output port through which the amplified laser beam L is output. In addition, both ends of the first optical waveguide 711, both ends of the second optical waveguide 712, both ends of the third optical waveguide 713, and the other end of the fourth optical waveguide 714 may correspond to auxiliary output ports.

[0127] A first monitoring device 971 and a second monitoring device 972 may be provided at both ends of the first optical waveguide 711, and a third monitoring device 973 and a fourth monitoring device 974 may be provided at both ends of the second optical waveguide 712. Furthermore, a fifth monitoring device 975 and a sixth monitoring device 976 may be provided at both ends of the third optical waveguide 713, and a seventh monitoring device 977 may be provided at the other end of the fourth optical waveguide 714. Each of the first to seventh monitoring devices 971 to 977 may include, for example, a photodiode.

[0128] The third monitoring device 973 and the fourth monitoring device 974 can monitor the wavelength alignment between the second ring resonator R2 and the third ring resonator R3, and the fifth monitoring device 975 and the sixth monitoring device 976 can monitor the wavelength alignment between the second ring resonator R2 and the third ring resonator R3. In addition, the first monitoring device 971, the second monitoring device 972, and the seventh monitoring device 977 can monitor the wavelength alignment between the first ring resonator R1 and the third ring resonator R3.

[0129] The tunable laser source 900 may include one or more optical delay lines 730 disposed on optical waveguides 711 , 712 , 713 , and 714 .

[0130] Figure 11 FIG. 1 shows a tunable laser source 1000 according to another example embodiment. In addition to the position of the optical delay line 830, Figure 11 The tunable laser source 1000 shown is Figure 10 The tunable laser source 900 shown is the same as that shown in FIG. Figure 11 , the tunable laser source 1000 may include one or more optical delay lines 830 disposed on a plurality of ring resonators R1 , R2 , and R3 .

[0131] Each of the tunable laser sources described in the above example embodiments may be used as a light source for a light steering device such as a LiDAR. Figure 12 A light redirecting device 2000 is shown according to an example embodiment.

[0132] refer to Figure 12 The light steering apparatus 2000 of the example embodiment may include a tunable laser source 2100, a steering device 2200 configured to steer light in a desired direction, a detector 2300 configured to detect the steered light, and a driver 2400. The driver 2400 may include a driving circuit configured to drive the tunable laser source 2100, the steering device 2200, and the detector 2300.

[0133] The tunable laser source 2100 may be one of the tunable laser sources 100 to 1000 of the above-described example embodiments.

[0134] The steering device 2200 can steer the laser beam incident from the tunable laser source 2100 in a desired direction. In addition, when the light is steered toward an object by the steering device 2200 and reflected from the object, the detector 2300 can detect the reflected light.

[0135] The steering device 2200 may include: a plurality of optical waveguides 2210 configured to split a laser beam incident from the tunable laser source 2100 into a plurality of laser beams and emit the laser beams; and a plurality of modulation units disposed on the optical waveguides 2210 to modulate the phases of the laser beams. An antenna array 2220 in which antennas are arranged in a one-dimensional form is disposed in the light output portion of the steering device 2200.

[0136] Two-dimensional optical scanning can be performed using the tunable laser source 2100 and the steering device 2200. For example, the phase of the laser beam can be controlled by using the steering device 2200 to scan the laser beam in a first direction ( Figure 12 The optical scanning is performed in the y-axis direction in the first direction, and the wavelength of the laser beam can be controlled by using the tunable laser source 2100 to scan the laser beam in the second direction ( Figure 12 As described above, when the tunable laser source 2100 is used as the light source of the light steering device 2000, two-dimensional optical scanning is possible even when the antenna array 2220 of the steering device 2200 is arranged in a one-dimensional form.

[0137] When a single-wavelength light source is used as a LiDAR light source, the antenna of the steering part is arranged in a two-dimensional form for two-dimensional optical scanning. However, in this case, since a large number of antennas, for example, 10,000 or more antennas, are required in each product, it is difficult to manufacture the product. In addition, light loss, reduction in control time, etc. may occur. However, when a tunable laser source according to an example embodiment is used as a LiDAR light source, two-dimensional optical scanning is possible even when the antenna of the steering device is arranged in a one-dimensional form, thereby reducing the number of antennas required for two-dimensional optical scanning and promoting commercialization. In addition, compared with the case of using a single-wavelength light source, light loss, increase in control time, etc. can be reduced.

[0138] The tunable laser sources 100 to 1000 described in the above exemplary embodiments can be used in various ways as light sources for integrated optical circuits in which optical elements are integrated. For example, in addition to being used in the aforementioned light redirection device 2000, the tunable laser sources 100 to 1000 can also be used in various fields including depth sensors and three-dimensional sensors. Furthermore, the tunable laser sources 100 to 1000 can be used as light sources for optical connections in data centers, such as light sources for wavelength division multiplexing (WDM) optical communications.

[0139] As described above, according to one or more of the above example embodiments, the tunable laser source includes three ring resonators, for example, a first ring resonator, a second ring resonator, and a third ring resonator having different lengths, and a ratio of the length of the third ring resonator to the length of the first ring resonator or a ratio of the length of the third ring resonator to the length of the second ring resonator is designed to be a number other than an integer, thereby improving mode selectivity and achieving a stable single oscillation mode.

[0140] According to an exemplary embodiment, a tunable laser source includes one or more optical delay lines disposed on an optical waveguide, thereby increasing the total length of the entire resonator and reducing the spectral linewidth in the oscillation mode. In addition, all components of the tunable laser source can be integrated on a single substrate through semiconductor processes, and thus the tunable laser source can be implemented as an on-chip tunable laser source.

[0141] According to an example embodiment, a tunable laser source includes one or more monitoring devices disposed on an output port of an optical waveguide to monitor wavelength alignment between ring resonators, thereby enabling on-chip control.

[0142] According to example embodiments, when a tunable laser source is used as a LiDAR light source, two-dimensional optical scanning is possible even when the antennas of the steering device are arranged in a one-dimensional form, thereby reducing the number of antennas required for two-dimensional optical scanning and promoting commercialization. Although example embodiments have been described, the example embodiments are for illustrative purposes only, and various modifications can be made therefrom by those skilled in the art.

[0143] 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 in each example embodiment should typically be considered as applicable to other similar features or aspects in other examples. Although example embodiments have been described with reference to the accompanying drawings, those skilled in the art will appreciate that various changes in form and details may be made without departing from the spirit and scope of the claims.

Claims

1. A tunable laser source, comprising: a plurality of optical waveguides, including a first optical waveguide, a second optical waveguide, and a third optical waveguide; at least three optical resonators disposed between the plurality of optical waveguides and optically coupled to the plurality of optical waveguides, the at least three optical resonators comprising a first ring resonator, a second ring resonator, and a third ring resonator having different lengths; as well as at least one optical amplifier disposed on at least one of the plurality of optical waveguides, wherein a ratio of a first length of a first optical resonator of the at least three optical resonators to a second length of a second optical resonator of the at least three optical resonators is not an integer, and The first ring resonator is directly disposed between the first optical waveguide and the second optical waveguide, the second ring resonator is directly disposed between the second optical waveguide and the third optical waveguide, and the third ring resonator is directly disposed between the first optical waveguide and the third optical waveguide.

2. The tunable laser source according to claim 1, wherein: The first ring resonator has a first perimeter; The second ring resonator has a second perimeter greater than the first perimeter; as well as The third ring resonator has a third circumference greater than the second circumference.

3. The tunable laser source according to claim 2, wherein: A first ratio of the third perimeter to the first perimeter or a second ratio of the third perimeter to the second perimeter is not an integer.

4. The tunable laser source according to claim 3, wherein: The first ratio of the third perimeter to the first perimeter or the second ratio of the third perimeter to the second perimeter is a rational number having at least two digits after a decimal point.

5. The tunable laser source according to claim 3, wherein: The first ratio of the third perimeter to the first perimeter or the second ratio of the third perimeter to the second perimeter is an irrational number.

6. The tunable laser source according to claim 2, wherein: A difference between the first perimeter and the second perimeter is 1% to 10% of the first perimeter.

7. The tunable laser source according to claim 1, further comprising controllers respectively disposed at the first ring resonator, the second ring resonator, and the third ring resonator, wherein the controllers are configured to adjust the refractive indices of the first ring resonator, the second ring resonator, and the third ring resonator, respectively.

8. The tunable laser source of claim 1, further comprising at least one optical delay line disposed on at least one of the plurality of optical waveguides.

9. The tunable laser source according to claim 1, further comprising at least one optical delay line disposed on at least one of the first ring resonator, the second ring resonator, and the third ring resonator.

10. The tunable laser source according to claim 1, further comprising a fourth ring resonator optically coupled to the third ring resonator. in, The size of the fourth ring resonator is equal to the size of the third ring resonator.

11. The tunable laser source of claim 1, further comprising at least one phase shifter disposed on at least one of the plurality of optical waveguides.

12. The tunable laser source of claim 1, further comprising at least one monitoring device disposed on at least one output port of at least one of the plurality of optical waveguides.

13. The tunable laser source according to claim 1, wherein: The tunable laser source forms a closed-loop resonator.

14. A light redirecting device comprising: Tunable laser source; as well as a steering device configured to steer the laser beam incident from the tunable laser source, Wherein, the tunable laser source comprises: a plurality of optical waveguides, including a first optical waveguide, a second optical waveguide, and a third optical waveguide; at least three optical resonators disposed between and optically coupled to the plurality of optical waveguides, the at least three optical resonators comprising a first ring resonator, a second ring resonator, and a third ring resonator having different lengths; and at least one optical amplifier disposed on at least one of the plurality of optical waveguides, wherein a ratio of a first length of a first optical resonator of the at least three optical resonators to a second length of a second optical resonator of the at least three optical resonators is not an integer, and The first ring resonator is directly disposed between the first optical waveguide and the second optical waveguide, the second ring resonator is directly disposed between the second optical waveguide and the third optical waveguide, and the third ring resonator is directly disposed between the first optical waveguide and the third optical waveguide.

15. The light redirecting device according to claim 14, wherein: The first ring resonator has a first perimeter; the second ring resonator has a second perimeter greater than the first perimeter; and the third ring resonator has a third perimeter greater than the second perimeter; as well as A first ratio of the third perimeter to the first perimeter or a second ratio of the third perimeter to the second perimeter is not an integer.

16. The light redirecting device according to claim 14, wherein: The tunable laser source further includes at least one monitoring device disposed on at least one output port of at least one of the plurality of optical waveguides.

17. The light redirecting apparatus of claim 14, further comprising a one-dimensional antenna array disposed in the light output portion of the redirecting device.

18. The light redirecting apparatus of claim 14, further comprising a detector configured to detect the laser beam redirected by the redirecting device.

19. A tunable laser source, comprising: a plurality of optical waveguides, including a first optical waveguide, a second optical waveguide, and a third optical waveguide; at least three optical resonators disposed between the plurality of optical waveguides and optically coupled to the plurality of optical waveguides, the at least three optical resonators comprising a first ring resonator, a second ring resonator, and a third ring resonator having different lengths; as well as at least one optical amplifier disposed on at least one of the plurality of optical waveguides, wherein a ratio of a first length of a first optical resonator of the at least three optical resonators to a second length of a second optical resonator of the at least three optical resonators is not an integer, wherein at least one of the at least three optical resonators is disposed on one side of the at least one optical amplifier, and at least two of the at least three optical resonators are disposed on another side of the at least one optical amplifier opposite to the one side, and The first ring resonator is directly disposed between the first optical waveguide and the second optical waveguide, the second ring resonator is directly disposed between the second optical waveguide and the third optical waveguide, and the third ring resonator is directly disposed between the first optical waveguide and the third optical waveguide.

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