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, such as externally optically injection locked lasers. [Background technology]

[0003] Optical injection synchronization Locking The technology of external optical injection locking (OIL) can narrow the laser linewidth, widen the modulation bandwidth, reduce chirp, and select and amplify signals, and 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, etc. It is one of the main means for improving the performance of modern optoelectronic devices and plays an important role in national defense and national economic construction, and external optical injection locking is one of the main means for achieving the above performance. External optical injection requires one-way injection, so an optical isolator is an essential device in the system. There are two main ways to realize external optical injection locking: (1) an injection-locked distributed feedback laser (DFB) laser in an individual optical fiber system; and (2) an injection-locked ring cavity laser in an individual optical fiber system. All of the above ways realize the function of injection locking based on individual components, and all of them use optical fibers to connect the individual components, and ensure the realization of related performance by using large-volume devices such as erbium-doped optical fiber amplifiers, polarization controllers, and integrated optical isolators. As a result, the entire external optical injection locking system has a non-uniform structure, a large volume, high energy consumption, and cannot be mass-produced. This makes it difficult to meet the needs for small volume, 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] The present application, 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 description 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; [Diagram 2] FIG. 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Diagram 3] FIG. 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 4] FIG. 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Diagram 5] Schematic diagram of the cross-sectional structure along the line 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] FIG. 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 9] FIG. 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 10] FIG. 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 11] FIG. 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 12] FIG. 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 13] FIG. 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 14] FIG. 1 is a plan view of another external optical injection-locked laser according to an embodiment of the present application; [Figure 15] FIG. 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 application and the change in internal loss due to the mirror 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 application and the change in modulation bandwidth due to internal loss. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The present application will be described below with reference to the drawings and examples. The specific examples described herein are merely for the purpose of interpreting the present application. For ease of explanation, only parts related 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, the input / output waveguide 3 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 the slave laser 2 is configured to emit laser light synchronized by the master laser 1 when the laser light emitted from the master laser 1 is injected. 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 in a directional coupling manner and 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 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. 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 made to coincide with each other, and the laser light output from the slave laser 2 and the laser light emitted from the master laser 1 are output after being combined through the input / output waveguide 3.

[0009] In one embodiment, the slave laser 2 includes a waveguide resonant cavity having a polygonal closed structure, the waveguide resonant cavity including a plurality of first total reflection mirrors 4 and a plurality of first straight waveguides 5, and the first total reflection mirror 4 is located between two adjacent first straight waveguides 5. Since the waveguide resonant cavity including the plurality of first total reflection mirrors 4 and the plurality of first straight waveguides 5 has a polygonal closed structure, the first straight waveguide 5 is located between two adjacent first total reflection mirrors 4. The first total reflection mirror 4 is configured to reflect the laser light transmitted through one first straight waveguide 5 to another first straight 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 a master laser 1, an input / output waveguide 3, and a slave laser 2 are arranged on the same substrate. Compared with a separate external optical injection-locked laser system, the chip-scale laser has the following advantages: (1) a compact structure and a small volume; (2) the same type of material is used and the thermal and mechanical performances are consistent, so the device is stable, reliable, and has a strong ability to withstand harsh environments; and (3) the device is designed and manufactured in a unified manner, so the device has good consistency and low cost. In addition, for the polygonal resonant cavity slave laser 2, the loss of the first straight waveguide 5 is independent of the size, and the loss of the first total reflection mirror 4 is inversely proportional to the perimeter, which greatly reduces the loss of the waveguide resonant cavity of the slave laser 2 and greatly reduces the dependency of the 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 one-way injection locking, which makes it possible to realize a chip-scale external optical injection locking laser, and has laid the foundation for its reliable application in the fields of high-speed direct modulation 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, and may be any laser whose laser oscillation mode is a single longitudinal mode or a fundamental transverse mode.

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

[0016] 3 is a plan view of another external optical injection-locked laser according to an embodiment of the present application, referring to FIG. 3, the waveguide resonant cavity is hexagonal. The laser light emitted from the master laser 1 is projected to the input / output waveguides 3, coupled by the input / output waveguides 3, enters the slave laser 2, passes through the six first straight 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] Exemplarily, 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 .

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

[0019] 4 is a plan view of another external optical injection-locked laser according to an embodiment of the present application, 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 the 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 the direction perpendicular to the extension direction of the input / output waveguide 3. In the embodiment of the present application, a portion of one 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 toward the slave laser 2 is formed at a position close to the slave laser 2. As a result, the distance between the first waveguide portion 311 and the corresponding first straight waveguide 5 is short, and the distance between the second waveguide portion 312 and the corresponding first total reflection mirror 4 is long, and the curved input / output waveguide 3 is adopted to bypass the deep etching surface of the first total reflection mirror 4, thereby realizing a larger coupling coefficient and at the same time ensuring that the first total reflection mirror 4 has a high reflectance.

[0020] In the vertical coupling structure, the first waveguide portion 311 (and the second waveguide portion 312) and the first straight 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 straight waveguide 5 overlap in a direction perpendicular to the substrate (i.e., Z direction). In the parallel coupling structure, the first waveguide portion 311 and the first straight waveguide 5 do not overlap in a direction perpendicular to the substrate. The overlap between the first waveguide portion 311 and the first straight waveguide 5 as shown in FIG. 4 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 straight waveguide 5 refers to a 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 a 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, which is closest to the input / output waveguides 3 in the waveguide resonant cavity, 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 first total reflection mirrors 4 that meet Less than .

[0023] 4 and 5, the external optical injection-locked laser includes 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 waveguide 3 are provided in the same layer. The first straight waveguide 5 includes a buffer layer 10, an active waveguide layer 13, and a cladding layer 14, the input / output waveguide 3 includes 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 waveguide 3 are provided in the same layer, and the slave laser 2 and the input / output waveguide 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 sequence. 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 the isolation layer 12, an active waveguide layer 13, and a covering layer 14, the input / output waveguide 3 comprises a buffer layer 10, a non-active waveguide layer 11, and a part of the isolation layer 12, the non-active 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 of the first straight waveguides 5 and the input / output waveguides 3 of the slave laser 2 is vertically coupled.

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

[0026] 5 and 6, the substrate 9 includes silicon (Si), indium phosphide (InP), gallium arsenide (GaAs), or gallium nitride (GaN). InP, GaAs, and GaN-based lasers are generally monolithically integrated external optical injection-locked lasers. According to integration technology, Si-based lasers are generally 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 Be The substrate, material and structure are determined according to the required wavelength. For example, in order to realize a high-speed directly modulated laser for optical fiber communication, an InP substrate may be adopted 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, which may be a corresponding quantum dot structure, or a p-type modulation doped quantum well (quantum dot) structure, an n-type modulation doped quantum well (quantum dot) structure, or the quantum well and quantum dot may be undoped, and the present 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, and referring to Fig. 7, the first total reflection mirror 4 is an etched cut surface that forms an acute angle (e.g., 45°) with the extension direction of the first straight waveguide 5. In the direction perpendicular to the substrate, deep etching is performed on the inactive waveguide layer 11 at a position where the inactive waveguide layer 11 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, and referring to FIG. 8, the first straight waveguide 5 closest to the input / output waveguide 3 is a coupled straight waveguide 51, and the coupled straight waveguide 51 and the input / output waveguide 3 adopt the same material and structure. In the embodiment of the present application, among the first straight waveguides 5 of the waveguide resonant cavity, the coupled straight waveguide 51 is manufactured using a non-active waveguide structure, and the remaining first straight waveguides 5 are manufactured using an active waveguide structure, and the coupled straight waveguide 51 and the input / output waveguides 3 adopt the same material and structure, so that the coupled straight waveguide 51 and the input / output waveguides 3 realize high coupling efficiency, are easy to manufacture, and do not cause large absorption loss.

[0031] In one embodiment, as shown in Fig. 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 particular, in terms of improving the modulation characteristics, the low-frequency roll-off effect can be effectively weakened and the modulation bandwidth can be greatly expanded.

[0032] 9 is a plan view of another external optical injection-locked laser according to an embodiment of the present application, refer to FIG. 9, the external optical injection-locked laser comprises at least two slave lasers 2, the at least two slave lasers 2 including 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, and 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 first sub-waveguide 321. The second sub-waveguide 322 is located on one side of the second slave laser 7, far 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, and then coupled again by the first slave laser 6 to enter the first sub-waveguide 321. The laser light is coupled by the first sub-waveguide 321 to enter the second slave laser 7, and then coupled by the second slave laser 7 to enter the second sub-waveguide 322, and continues to propagate in 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, and 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, and continues to propagate in the second sub-waveguide 322.

[0035] 11 is a plan view of another external optical injection-locked laser according to an embodiment of the present application, refer to FIG. 11, the external optical injection-locked laser comprises at least two slave lasers 2, the at least two slave lasers 2 including 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, and the at least two slave lasers 2 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, and 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 of the back-reflected (scattered) light of the external optical injection-locked laser, and improves 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, 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 the other second straight waveguide 33.

[0039] 14 , the plurality of second straight 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 to 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 by the second total reflection mirror 16 again, 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 to the first input / output sub-waveguide 331 again by the first straight waveguide 5 of the slave laser 2, is reflected by the second total reflection mirror 16 again 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 by the second total reflection mirror 16 again to the third input / output sub-waveguide 333 to continue propagating. In order to improve the manufacturing quality of the total reflection mirror and reduce the loss of the total reflection mirror, 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 external optical 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. 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 the embodiment of the present application, 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 again coupled 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 to continue propagating. Since the embodiment of the present application has a small number of second total reflection mirrors 16 and second straight waveguides 33, loss due to total reflection mirrors is reduced.

[0041] The application value of the technical aspects of the present application is demonstrated by taking the simulation performance of a monolithically integrated external optical injection-locked high-speed direct modulation semiconductor laser as an example. As can be seen from Figure 16, for a rectangular cavity laser, if the first total reflection mirror 4 with a power reflectivity of 89.3% or more is manufactured, its internal loss is lower than 38.2 cm-1, which is much smaller than that of a ring laser. As can be seen from Figure 17, with the increase in the internal loss of the ring laser and the extension of its resonant cavity, the modulation bandwidth of the laser gradually decreases, but if the internal loss is controlled to be smaller than 38.2 cm-1, the minimum modulation bandwidth still exceeds 25 GHz. It can fully meet the current high-speed modulation and data communication use of lasers, and is a desirable light source in the optical communication 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. External optical injection-locked laser.

2. The waveguide resonant cavity has a polygonal closed structure including a plurality of first total reflection mirrors and a plurality of first straight waveguides, and the first total reflection mirrors are located between two adjacent first straight waveguides.

2. The external optical injection locked laser of claim 1.

3. The waveguide resonant cavity has a ring structure or a racetrack structure.

2. The external optical injection locked laser of claim 1.

4. The waveguide resonant cavity has a triangular, rectangular or hexagonal shape.

3. The externally optically injection locked laser of claim 2.

5. the input / output waveguide comprises a first waveguide portion and a second waveguide portion; When projected perpendicular to the substrate, the first waveguide portion overlaps with the first straight 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, In a projection perpendicular to the substrate, a distance between the first waveguide portion and the waveguide resonant cavity is smaller than a distance between the second waveguide portion and the waveguide resonant cavity in a direction perpendicular to an extension direction of the input / output waveguides.

3. The externally optically injection locked laser of claim 2.

6. 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; 3. An external optical injection locked laser according to claim 1 or 2.

7. the first straight waveguide that is closest to the input / output waveguide is a coupled straight waveguide, and the coupled straight waveguide and the input / output waveguide adopt the same material and structure; 3. An external optical injection locked laser according to claim 1 or 2.

8. 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; In a projection perpendicular to the substrate, the first slave laser and the second slave laser are located on both sides of the input / output waveguide.

3. An external optical injection locked laser according to claim 1 or 2.

9. 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; In a projection perpendicular to the substrate, the first slave laser and the second slave laser are located on the same side of the input / output waveguide.

3. An external optical injection locked laser according to claim 1 or 2.

10. the slave lasers include at least two 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 perpendicular to the substrate, 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.

3. An external optical injection locked laser according to claim 1 or 2.

11. further comprising an optical isolator located in a transmission path of the input / output waveguide and between the master laser and the slave laser; 3. An external optical injection locked laser according to claim 1 or 2.

12. the input / output waveguide includes a plurality of second total reflection mirrors and a plurality of second straight waveguides, and the second total reflection mirror is located between two adjacent second straight waveguides; 3. The externally optically injection locked laser of claim 2.

Images