External optical injection-locked laser

Abstract

An external optical injection-locked laser including a master laser (1), an input / output waveguide (3), and a slave laser (2) formed on the same substrate (9), in which the master laser (1) is configured to emit laser light to the input / output waveguide (3), the input / output waveguide (3) is configured to inject the laser light emitted from the master laser (1) into the slave laser (2) by a directional coupling method and output the laser light emitted from the master laser (1) and the slave laser (2), the slave laser (2) has a waveguide resonant cavity, the slave laser (2) is configured to emit laser light after making the laser light generated by the slave laser (2) coherent with the laser light injected from the master laser (1), and the laser light emitted from the slave laser (2) is synchronized by the master laser (1).

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority based on a Chinese patent application bearing application number 202210260097.4, filed with the China Patent Office on March 16, 2022, the entire contents of which are incorporated herein by reference.

[0002] This application relates to semiconductor optoelectronics, for example, externally optically injection-locked lasers. [Background technology]

[0003] Optical injection synchronization Locking OIL (Optical Injection Locking) technology can narrow the laser linewidth, widen the modulation bandwidth, reduce chirp, and select and amplify signals. It can be used in coherent detection, laser radar, laser ranging, high-speed directly modulated lasers, optical amplifiers, phase-sensitive amplifiers, dense wavelength division multiplexing technology, radio frequency waveform generation, and optical waveform synthesis. It is one of the main means of improving the performance of modern optoelectronic devices and plays an important role in national defense and national economic development. External optical injection locking is one of the main means of achieving the above performance. External optical injection requires one-way injection, making an optical isolator an essential device in the system. External optical injection locking can be achieved mainly in two ways: (1) an injection-locked distributed feedback (DFB) laser in a discrete optical fiber system; and (2) an injection-locked ring cavity laser in a discrete optical fiber system. Both of these methods rely on discrete components to achieve the injection locking function, and all rely on optical fiber to connect the discrete components, using bulky devices such as erbium-doped optical fiber amplifiers, polarization controllers, and integrated optical isolators to achieve the relevant performance. Therefore, the overall structure of the external optical injection locking system is uneven, bulky, consumes high energy, and cannot be mass-produced. This makes it difficult to meet the needs for small size, low power consumption, low cost, and large-scale market application in the application fields of high-performance optoelectronic devices. Summary of the Invention [Problem to be solved by the invention]

[0004] The present application provides a chip-scale external optical injection-locked laser that has a compact structure, a small volume, a stable and reliable device, a strong ability to withstand harsh environments, good device consistency, and low cost. [Means for solving the problem]

[0005] This application is a master laser, an input / output waveguide, and a slave laser formed on the same substrate; the master laser is configured to emit laser light into the input / output waveguides; the input / output waveguide is configured to inject laser light emitted from the master laser into the slave laser; The slave laser includes a waveguide resonant cavity and is configured to emit laser light synchronized by the master laser when laser light emitted from the master laser is injected into the slave laser. An external optical injection-locked laser is provided. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a plan view of an external optical injection-locked laser according to an embodiment of the present application; [Figure 2] 1 is a plan view of another externally optically injection-locked laser according to an embodiment of the present application; [Figure 3] 1 is a plan view of another externally optically injection-locked laser according to an embodiment of the present application; [Figure 4] 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 5] Schematic diagram of the cross-sectional structure along AA' in Figure 4 [Figure 6] 1 is a cross-sectional view of an external optical injection-locked laser according to an embodiment of the present application; [Figure 7] Schematic diagram of the structure of a first total reflection mirror according to an embodiment of the present application. [Figure 8] 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 9] 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 10] 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 11] 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 12] 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 13] 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 14] 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 15] 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 16] FIG. 1 is a diagram showing the relationship between the length of the resonant cavity of a rectangular cavity laser according to an embodiment of the present invention and the change in internal loss due to the specular reflectance of the total reflection mirror. [Figure 17] FIG. 1 is a diagram showing the relationship between the length of the resonant cavity of a ring laser according to an embodiment of the present invention and the change in modulation bandwidth due to the internal loss. DETAILED DESCRIPTION OF THE INVENTION

[0007] The present application will be described below with reference to the drawings and examples. The specific examples described here are merely for the purpose of interpreting the present application. For ease of explanation, only parts relevant to the present application are shown in the drawings.

[0008] FIG. 1 is a plan view of an external optical injection-locked laser according to an embodiment of the present application. Referring to FIG. 1, the external optical injection-locked laser includes a master laser 1, an input / output waveguide 3, and a slave laser 2 formed on the same substrate (not shown in FIG. 1). The master laser 1 is configured to emit laser light to the input / output waveguide 3, which is configured to inject the laser light emitted from the master laser 1 into the slave laser 2. The slave laser 2 includes a waveguide resonant cavity, and is configured to emit laser light synchronized by the master laser 1 when the laser light emitted from the master laser 1 is injected into the slave laser 2. For example, the input / output waveguide 3 is configured to inject the laser light emitted from the master laser 1 into the slave laser 2 by directional coupling and to output the laser light emitted from the master laser 1 and the slave laser 2. The slave laser 2 is configured to emit laser light after making its own laser light coherent with the laser light injected from the master laser 1, and the laser light emitted from the slave laser 2 is synchronized by the master laser 1. The laser light emitted from the master laser 1 is injected into the slave laser 2 through the input / output waveguide 3, whereby the laser light emitted from the slave laser 2 is synchronized by the master laser 1, the laser oscillation wavelengths of the slave laser 2 and the master laser 1 are matched, and the laser light output from the slave laser 2 and the laser light emitted from the master laser 1 are combined by the input / output waveguide 3 and then output.

[0009] In one embodiment, the slave laser 2 includes a waveguide resonant cavity having a polygonal closed structure, and the waveguide resonant cavity includes a plurality of first total reflection mirrors 4 and a plurality of first linear waveguides 5, and the first total reflection mirror 4 is located between two adjacent first linear waveguides 5. Since the waveguide resonant cavity consisting of the plurality of first total reflection mirrors 4 and the plurality of first linear waveguides 5 has a polygonal closed structure, the first linear waveguide 5 is located between two adjacent first total reflection mirrors 4. The first total reflection mirror 4 is configured to reflect laser light transmitted through one first linear waveguide 5 to another first linear waveguide 5.

[0010] In one embodiment, the waveguide resonant cavity may exhibit a ring structure or a racetrack type structure.

[0011] The embodiment of the present application provides an external optical injection-locked laser in which the master laser 1, input / output waveguide 3, and slave laser 2 are mounted on the same substrate. Compared with a separate external optical injection-locked laser system, this chip-scale laser has the following advantages: (1) a compact structure and small volume; (2) the same type of material is used, and the thermal and mechanical performances are consistent, making the device stable and reliable, and it has a strong ability to withstand harsh environments; and (3) the device is designed and manufactured in a unified manner, resulting in good device consistency and low cost. In addition, for the polygonal resonant cavity slave laser 2, the loss of the first linear waveguide 5 is independent of size, and the loss of the first total reflection mirror 4 is inversely proportional to the perimeter, which significantly reduces the loss of the waveguide resonant cavity of the slave laser 2 and greatly reduces the dependency of loss on the size of the waveguide resonant cavity. At the same time, the polygonal waveguide resonant cavity has the traveling wave transmission characteristics of a ring cavity, does not require an optical isolator, and enables unidirectional injection locking. This makes it possible to realize a chip-scale external optical injection-locked laser, which has certainly laid the foundation for its application in fields such as high-speed directly modulated lasers, narrow linewidth lasers, signal selection and amplification, etc.

[0012] The master laser 1 is a single longitudinal mode semiconductor laser, and the master laser 1 unidirectionally injection locks a counterclockwise (CCW) optical mode in the slave laser 2. The master laser 1 may be a DFB laser or a distributed Bragg reflector (DBR) laser, or may be a passively loop-coupled laser, as long as its lasing mode is a single longitudinal mode, fundamental transverse mode.

[0013] Referring to FIG. 1, the waveguide resonant cavity has a rectangular shape. The laser light emitted from the master laser 1 is projected onto the input / output waveguides 3, coupled by the input / output waveguides 3, enters the slave laser 2, passes through the four first linear waveguides 5 of the waveguide resonant cavity in a counterclockwise direction along the arrow direction shown in FIG. 1, is coupled to the input / output waveguides 3, and continues to propagate along the input / output waveguides 3.

[0014] In other embodiments, the waveguide resonant cavity may be a polygon of other shapes, including but not limited to, a triangle and a hexagon, and the number of sides of the polygon of the waveguide resonant cavity may be determined according to actual needs.

[0015] 2 is a plan view of another external optical injection-locked laser according to an embodiment of the present application, and the waveguide resonant cavity is triangular. The laser light emitted from the master laser 1 is projected into the input / output waveguides 3, coupled by the input / output waveguides 3, enters the slave laser 2, passes through the three first linear waveguides 5 of the waveguide resonant cavity counterclockwise along the arrow direction shown in FIG. 2, is coupled to the input / output waveguides 3, and continues to propagate along the input / output waveguides 3.

[0016] 3 is a plan view of another external optical injection-locked laser according to an embodiment of the present application, in which the waveguide resonant cavity is hexagonal. The laser light emitted from the master laser 1 is projected into the input / output waveguides 3, coupled by the input / output waveguides 3, enters the slave laser 2, passes through the six first linear waveguides 5 of the waveguide resonant cavity counterclockwise along the arrow direction shown in FIG. 3, is coupled to the input / output waveguides 3, and continues to propagate along the input / output waveguides 3.

[0017] Illustratively, with reference to FIGS. 1 to 3, one first straight waveguide 5 of the slave laser 2 is coupled to the input / output waveguide 3. In the example shown in FIG.

[0018] In one embodiment, the first straight waveguides 5 of the slave laser 2 are coupled to the input and output waveguides 3 .

[0019] FIG. 4 is a plan view of another external optical injection-locked laser according to an embodiment of the present invention, and FIG. 5 is a schematic diagram of a cross-sectional structure along AA′ in FIG. 4 , in which the input / output waveguide 3 includes a first waveguide portion 311 and a second waveguide portion 312. The input / output waveguide 3 extends along the X direction. In a projection perpendicular to the substrate (i.e., along the Z direction), the first waveguide portion 311 overlaps with the first straight waveguide 5, and the second waveguide portion 312 overlaps with the first total reflection mirror 4 in a direction perpendicular to the extension direction of the input / output waveguide 3 (i.e., along the Y direction). That is, in a projection perpendicular to the substrate, the first waveguide portion 311 corresponds to the first straight waveguide 5, and the second waveguide portion 312 corresponds to the first total reflection mirror 4. In a projection perpendicular to the substrate, the distance between the first waveguide portion 311 and the waveguide resonant cavity is smaller than the distance between the second waveguide portion 312 and the waveguide resonant cavity in a direction perpendicular to the extension direction of the input / output waveguide 3. In this embodiment, a portion of the first straight waveguide 5 of the slave laser 2 is coupled to the input / output waveguide 3. The input / output waveguide 3 is a curved waveguide, and a protrusion is formed toward the slave laser 2 at a position close to the slave laser 2. As a result, the distance between the first waveguide portion 311 and its corresponding first straight waveguide 5 is short, and the distance between the second waveguide portion 312 and its corresponding first total reflection mirror 4 is long. The curved input / output waveguide 3 is used to bypass the deep-etched surface of the first total reflection mirror 4, achieving a larger coupling coefficient and ensuring that the first total reflection mirror 4 has a high reflectivity.

[0020] In the vertically coupled structure, the first waveguide portion 311 (and the second waveguide portion 312) and the first linear waveguide 5 are located in different film layers, and the first total reflection mirror 4 is a plane perpendicular to the substrate. The first waveguide portion 311 and the first linear waveguide 5 overlap in a direction perpendicular to the substrate (i.e., the Z direction). In the parallel coupled structure, the first waveguide portion 311 and the first linear waveguide 5 do not overlap in a direction perpendicular to the substrate. As shown in FIG. 4, the overlap between the first waveguide portion 311 and the first linear waveguide 5 is along the Y direction, and the overlap between the second waveguide portion 312 and the first total reflection mirror 4 is also along the Y direction. The correspondence between the first waveguide portion 311 and the first linear waveguide 5 refers to the correspondence between them along the Y direction in the XY plane, and the correspondence between the second waveguide portion 312 and the first total reflection mirror 4 also refers to the correspondence between them along the Y direction in the XY plane.

[0021] In one embodiment, the geometric center of the waveguide resonant cavity may be used as the starting point for distance calculation, while in another embodiment, the first straight waveguide 5 in the waveguide resonant cavity, which is closest to the input and output waveguides 3, may be used as the starting point for distance calculation.

[0022] In one embodiment, the first waveguide portion 311 and the second waveguide portion 312 The sum of the lengths of teeth ,next The length of the first straight waveguide 5 between the two opposing first total reflection mirrors 4 Less than .

[0023] 4 and 5, the external optical injection-locked laser comprises a substrate 9, a buffer layer 10, a non-active waveguide layer 11 (or an active waveguide layer 13), a cladding layer 14, and a contact layer 15, which are laminated in this order. The active waveguide layer 13 of the waveguide resonant cavity and the non-active waveguide layer 11 of the input / output waveguides 3 are provided in the same layer. The first straight waveguide 5 comprises a buffer layer 10, an active waveguide layer 13, and a cladding layer 14, the input / output waveguides 3 comprise a buffer layer 10, a non-active waveguide layer 11, and a cladding layer 14, the non-active waveguide layer 11 and the active waveguide layer 13 are provided in the same layer, the first straight waveguide 5 and the input / output waveguides 3 are provided in the same layer, and the slave laser 2 and the input / output waveguides 3 are coupled in parallel.

[0024] 6 is a cross-sectional view of an external optical injection-locked laser according to an embodiment of the present application. Referring to FIG. 6, the external optical injection-locked laser includes a substrate 9, a buffer layer 10, a non-active waveguide layer 11, an isolation layer 12, an active waveguide layer 13, a cladding layer 14, and a contact layer 15, which are stacked in this order. In a direction perpendicular to the substrate, an input / output waveguide 3 is located between the substrate 9 and a first straight waveguide 5. The first straight waveguide 5 comprises a part of an isolation layer 12, an active waveguide layer 13, and a covering layer 14, the input / output waveguide 3 comprises a buffer layer 10, an inactive waveguide layer 11, and a part of the isolation layer 12, the inactive waveguide layer 11 and the active waveguide layer 13 are stacked, the first straight waveguide 5 and the input / output waveguides 3 are stacked, the first straight waveguide 5 and the input / output waveguides 3 overlap along the Z direction, and one first straight waveguide 5 and the input / output waveguide 3 of the slave laser 2 are vertically coupled.

[0025] The waveguide resonant cavity has a polygonal closed structure and includes a plurality of first linear waveguides 5. All of the first linear waveguides 5 have the same film layer structure. In one embodiment, And all All the first linear waveguides 5 each include a part of an isolation layer 12, an active waveguide layer 13, and a cladding layer 14, and all the first linear waveguides 5 are made of the same material.

[0026] 5 and 6, the substrate 9 includes silicon (Si), indium phosphide (InP), gallium arsenide (GaAs), or gallium nitride (GaN). Lasers based on InP, GaAs, and GaN are usually monolithically integrated external optical injection-locked lasers. According to integration technology, lasers based on Si are usually hybrid integrated external optical injection-locked lasers such as hetero-integrated or butt-coupled.

[0027] Illustratively, with reference to FIGS. 5 and 6, the active waveguide layer 13 is a quantum well structure, a quantum dot structure, an n-type modulation doped quantum well structure, an n-type modulation doped quantum dot structure, a p-type modulation doped quantum well structure, or a p-type modulation doped quantum dot structure.

[0028] Illustratively, the materials and structures of the master and slave lasers according to the embodiments of the present application may be selected depending on the application of the laser. Decide fixed And The substrate, material, and structure are determined according to the required wavelength. For example, to realize a high-speed directly modulated laser for optical fiber communication, an InP substrate may be used to realize a monolithically integrated external optical injection laser, and the active waveguide layer may adopt an InGaAsP / InGaAsP, InGaAlAs / InGaAlAs, InGaAsP, or InGaAlAs quantum well structure, and the corresponding quantum dot structure, or a p-type modulation doped quantum well (quantum dot) structure, or an n-type modulation doped quantum well (quantum dot) structure, or the quantum well and quantum dots may be undoped; this application does not require or particularly limit this.

[0029] 7 is a structural schematic diagram of a first total reflection mirror according to an embodiment of the present application. Referring to FIG. 7, the first total reflection mirror 4 has an etched cut surface that forms an acute angle (e.g., 45°) with the extension direction of the first linear waveguide 5. In the direction perpendicular to the substrate, deep etching is performed on the inactive waveguide layer 11 at a position that overlaps with the first total reflection mirror 4, to form a recessed groove.

[0030] 8 is a plan view of another external optical injection-locked laser according to an embodiment of the present application. Referring to FIG. 8, the first straight waveguide 5 closest to the input and output waveguides 3 is a coupled straight waveguide 51, and the coupled straight waveguide 51 and the input and output waveguides 3 are made of the same material and have the same structure. In this embodiment, of the first straight waveguides 5 of the waveguide resonant cavity, the coupled straight waveguide 51 is fabricated using a non-active waveguide structure, while the remaining first straight waveguides 5 are fabricated using an active waveguide structure. Since the coupled straight waveguide 51 and the input and output waveguides 3 are made of the same material and have the same structure, the coupled straight waveguide 51 and the input and output waveguides 3 achieve high coupling efficiency, are easy to fabricate, and do not suffer from large absorption loss.

[0031] In one embodiment, as shown in Figure 8, the external optical injection-locked laser includes one slave laser 2. In another embodiment, the external optical injection-locked laser may include multiple slave lasers 2, thereby improving the overall device performance. In terms of improving the modulation characteristics, the low-frequency roll-off effect can be effectively reduced and the modulation bandwidth can be significantly widened.

[0032] 9 is a plan view of another external optical injection-locked laser according to an embodiment of the present application. Referring to FIG. 9, the external optical injection-locked laser includes at least two slave lasers 2, and the at least two slave lasers 2 include a first slave laser 6 and a second slave laser 7. In a projection perpendicular to the substrate, the first slave laser 6 and the second slave laser 7 are located on both sides of the input / output waveguide 3. In the embodiment of the present application, the first slave laser 6 and the second slave laser 7 form a parallel structure.

[0033] 9, the input / output waveguide 3 includes a first sub-waveguide 321 and a second sub-waveguide 322. In a projection perpendicular to the substrate, the first slave laser 6 and the second slave laser 7 are located on either side of the first sub-waveguide 321. The second sub-waveguide 322 is located on one side of the second slave laser 7, farther from the first sub-waveguide 321. The laser light emitted from the master laser 1 is projected into the first sub-waveguide 321, coupled by the first sub-waveguide 321 to enter the first slave laser 6, coupled again by the first slave laser 6 to enter the first sub-waveguide 321, coupled by the first sub-waveguide 321 to enter the second slave laser 7, coupled by the second slave laser 7 to enter the second sub-waveguide 322, and continues to propagate through the second sub-waveguide 322.

[0034] 10 is a plan view of another external optical injection-locked laser according to an embodiment of the present application. Referring to FIG. 10, the input / output waveguide 3 includes a first sub-waveguide 321 and a second sub-waveguide 322. In a projection perpendicular to the substrate, the first slave laser 6 corresponds to the first sub-waveguide 321. The second sub-waveguide 322 corresponds to the second slave laser 7. The laser light emitted from the master laser 1 is projected into the first sub-waveguide 321, coupled by the first sub-waveguide 321 to enter the first slave laser 6, and then coupled again by the first slave laser 6 to enter the first sub-waveguide 321. The laser light is transmitted by the first sub-waveguide 321 to the second sub-waveguide 322, then coupled to enter the second slave laser 7, and then coupled by the second slave laser 7 to enter the second sub-waveguide 322, where it continues to propagate.

[0035] 11 is a plan view of another external optical injection-locked laser according to an embodiment of the present application. Referring to FIG. 11, the external optical injection-locked laser includes at least two slave lasers 2, and the at least two slave lasers 2 include a first slave laser 6 and a second slave laser 7. In a projection perpendicular to the substrate, the first slave laser 6 and the second slave laser 7 are located on the same side of the input / output waveguide 3. In the embodiment of the present application, the first slave laser 6 and the second slave laser 7 form a serial structure.

[0036] 12 is a plan view of another external optical injection-locked laser according to an embodiment of the present application. Referring to FIG. 12, the external optical injection-locked laser includes at least two slave lasers 2, which include a first slave laser 6, a second slave laser 7, and a third slave laser 17. In a projection perpendicular to the substrate, the first slave laser 6 and the second slave laser 7 are located on the same side of the input / output waveguide 3, the first slave laser 6 and the third slave laser 17 are located on both sides of the input / output waveguide 3, and the second slave laser 7 and the third slave laser 17 are located on both sides of the input / output waveguide 3. In the embodiment of the present application, the first slave laser 6, the second slave laser 7, and the third slave laser 17 form a series-parallel structure.

[0037] 13 is a plan view of another external optical injection-locked laser according to an embodiment of the present application. Referring to Fig. 13, the external optical injection-locked laser further includes an optical isolator 8, which is located in the transmission path of the input / output waveguide 3, and is located between the master laser 1 and the slave laser 2. In the embodiment of the present application, the provision of the optical isolator 8 avoids interference with back-reflected (scattered) light of the external optical injection-locked laser, improving the performance of the external optical injection-locked laser.

[0038] FIG. 14 is a plan view of another external optical injection-locked laser according to an embodiment of the present application. Referring to FIG. 14, the input / output waveguide 3 includes a plurality of second total reflection mirrors 16 and a plurality of second straight waveguides 33, and the second total reflection mirror 16 is located between two adjacent second straight waveguides 33, and the second total reflection mirror 16 is configured to reflect laser light in one second straight waveguide 33 to another second straight waveguide 33.

[0039] 14 , the plurality of second linear waveguides 33 include a first input / output sub-waveguide 331, a second input / output sub-waveguide 332, and a third input / output sub-waveguide 333. The first input / output sub-waveguide 331 and the third input / output sub-waveguide 333 extend along the X direction and are arranged in parallel. The second input / output sub-waveguide 332 extends along the Y direction, and one end of the second input / output sub-waveguide 332 is connected to the first input / output sub-waveguide 331, and the other end of the second input / output sub-waveguide 332 is connected to the third input / output sub-waveguide 333. The laser light projected into the third input / output sub-waveguide 333 is reflected by the second total reflection mirror 16, enters the second input / output sub-waveguide 332, is reflected again by the second total reflection mirror 16, enters the first input / output sub-waveguide 331, is coupled to the first straight waveguide 5 of the slave laser 2 by the first input / output sub-waveguide 331, is coupled again to the first input / output sub-waveguide 331 by the first straight waveguide 5 of the slave laser 2, is reflected again by the second total reflection mirror 16 at the end of the first input / output sub-waveguide 331, enters the second input / output sub-waveguide 332, is transmitted through the second input / output sub-waveguide 332, and is reflected again by the second total reflection mirror 16 to the third input / output sub-waveguide 333 for continued propagation. In order to improve the manufacturing quality of the total reflection mirrors and reduce loss in the total reflection mirrors, the second total reflection mirror 16 and the first total reflection mirror 4 are designed and manufactured to be misaligned.

[0040] 15 is a plan view of another externally optically injection-locked laser according to an embodiment of the present application. Referring to FIG. 15, the plurality of second straight waveguides 33 include a first input / output sub-waveguide 331 and a second input / output sub-waveguide 332, and the first input / output sub-waveguide 331 and the second input / output sub-waveguide 332 are connected to each other. The first input / output sub-waveguide 331 extends along the X direction, and the second input / output sub-waveguide 332 extends along the Y direction. In this embodiment, the laser light emitted from the master laser 1 is directly projected into the second input / output sub-waveguide 332, reflected by the second total reflection mirror 16, enters the first input / output sub-waveguide 331, is coupled to the first straight waveguide 5 of the slave laser 2 by the first input / output sub-waveguide 331, is coupled again to the first input / output sub-waveguide 331 by the first straight waveguide 5 of the slave laser 2, and is reflected by the second total reflection mirror 16 at the end of the first input / output sub-waveguide 331 to the second input / output sub-waveguide 332, where it continues to propagate. Since the embodiment of the present application includes a small number of second total reflection mirrors 16 and second straight waveguides 33, loss due to the total reflection mirrors is reduced.

[0041] The application value of the technical aspects of this application is demonstrated by using the simulated performance of a monolithically integrated, externally optically injection-locked, high-speed, directly modulated semiconductor laser as an example. As can be seen from Figure 16, for a rectangular cavity laser, if the first total reflection mirror 4 is manufactured with a power reflectivity of 89.3% or more, its internal loss will be lower than 38.2 cm-1, much lower than that of a ring laser. As can be seen from Figure 17, as the internal loss of a ring laser increases and its resonant cavity is extended, the modulation bandwidth of the laser gradually decreases. However, if the internal loss is controlled to be lower than 38.2 cm-1, the minimum modulation bandwidth will still exceed 25 GHz. This laser can fully meet the current high-speed modulation and data communication requirements, making it a desirable light source in the optical communications field.

Claims

1. a master laser, an input / output waveguide, and a slave laser formed on the same substrate; the master laser is configured to emit laser light into the input / output waveguides; the input / output waveguide is configured to inject laser light emitted from the master laser into the slave laser through the input / output waveguide; the slave laser includes a waveguide resonant cavity and is configured to emit laser light synchronized by the master laser when laser light emitted from the master laser is injected into the slave laser; the waveguide resonant cavity has a polygonal closed structure including a plurality of first total reflection mirrors and a plurality of first linear waveguides, and the first total reflection mirrors are located between two adjacent first linear waveguides; External optical injection-locked laser.

2. The waveguide resonant cavity exhibits a triangular, rectangular, or hexagonal shape.

2. The externally optically injection-locked laser of claim 1.

3. the input / output waveguide comprises a first waveguide portion and a second waveguide portion; When projected onto a plane on which the substrate is located, the first waveguide portion overlaps with the first linear waveguide, and the second waveguide portion overlaps with the first total reflection mirror in a direction perpendicular to an extension direction of the input / output waveguides; a distance between the first waveguide portion and the waveguide resonant cavity in a direction perpendicular to an extension direction of the input / output waveguides when projected onto a plane on which the substrate is located, is smaller than a distance between the second waveguide portion and the waveguide resonant cavity; 2. The externally optically injection-locked laser of claim 1.

4. the waveguide resonant cavity and the input / output waveguide are provided in the same layer, or the input / output waveguide is located between the substrate and the waveguide resonant cavity in a direction perpendicular to the substrate.

2. The externally optically injection-locked laser of claim 1.

5. the first straight waveguide closest to the input / output waveguide is a coupled straight waveguide, and the coupled straight waveguide and the input / output waveguide are made of the same material and have the same structure; 2. The externally optically injection-locked laser of claim 1.

6. the number of the slave lasers is at least two, and the at least two slave lasers include a first slave laser and a second slave laser; When projected onto a plane on which the substrate is located, the first slave laser and the second slave laser are located on both sides of the input / output waveguide, with the input / output waveguide as a boundary.

2. The externally optically injection-locked laser of claim 1.

7. the number of the slave lasers is at least two, and the at least two slave lasers include a first slave laser and a second slave laser; When projected onto a plane on which the substrate is located, the first slave laser and the second slave laser are located on the same side of the input / output waveguide, with the input / output waveguide as a boundary.

2. The externally optically injection-locked laser of claim 1.

8. the slave lasers include at least two slave lasers in number, the at least two slave lasers including a first slave laser, a second slave laser, and a third slave laser; In a projection onto a plane on which the substrate is located, the first slave laser and the second slave laser are located on the same side of the input / output waveguide, and the first slave laser and the third slave laser are located on both sides of the input / output waveguide.

2. The externally optically injection-locked laser of claim 1.

9. further comprising an optical isolator located in a transmission path of the input / output waveguide and between the master laser and the slave laser; 2. The externally optically injection-locked laser of claim 1.

10. the input / output waveguides include a plurality of second total reflection mirrors and a plurality of second straight waveguides, and the second total reflection mirrors are located between two adjacent second straight waveguides; 2. The externally optically injection-locked laser of claim 1.

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