Lasers, Optical Modules, and Devices

Abstract

A laser, optical module, and device are provided. The laser includes a gain region waveguide (11), a feedback waveguide (12), a first end face (R1), and a second end face (R2). The gain region waveguide (11) and the feedback waveguide (12) are disposed between the first end face (R1) and the second end face (R2), with the end of the gain region waveguide (11) connected to the end of the feedback waveguide (12), and the feedback waveguide (12) is disposed on the side of the gain region waveguide (11) that is closest to the second end face (R2). The first end face (R1) and the second end face (R2) are configured to transmit light into the gain region waveguide (11) and the feedback waveguide (12), and the first end face (R1) is configured to transmit laser light. The feedback waveguide (12) is disposed so as to increase the equivalent cavity length of the laser and thereby compress the linewidth of the laser. Furthermore, the integration density of the laser can be improved, and the material costs and processing costs of the laser can be reduced.

Description

[Technical Field]

[0001] The present application relates to the field of communications technology, and in particular to lasers, optical modules, and devices. [Background technology]

[0002] With the gradual increase in bandwidth in the future, optical communication technology will be gradually applied more widely, and optical communication technology may even be applied in wireless scenarios. However, optical communication technology imposes higher requirements on the laser linewidth. For example, based on quadrature amplitude modulation (QAM16), the mainstream modulation method in current communication technology, the laser linewidth needs to be less than 5 MHz. The higher the modulation frequency, the higher the linewidth requirement. Furthermore, narrowing the linewidth also helps reduce the power consumption of optical digital signal processing (oDSP). Therefore, how to narrow the laser linewidth is a technical issue that needs to be solved urgently. Summary of the Invention

[0003] SUMMARY OF THE INVENTION Embodiments of the present application provide lasers, optical modules, and apparatus for narrowing the linewidth of a laser.

[0004] According to a first aspect, one embodiment of the present application provides a laser. The laser may be of various types. For example, the laser may be a distributed feedback laser (DFB). The laser in this embodiment of the present application may include a gain region waveguide, a feedback waveguide, a first end facet, and a second end facet. The gain region waveguide and the feedback waveguide are disposed between the first end facet and the second end facet, an end of the gain region waveguide is connected to an end of the feedback waveguide, and the feedback waveguide is disposed on a side of the gain region waveguide that is adjacent to the second end facet. The first end facet and the second end facet are configured to transmit light into the gain region waveguide and the feedback waveguide, and the first end facet is configured to transmit laser light.

[0005] In this embodiment of the present application, both the gain region waveguide and the feedback waveguide are waveguides having an optical transmission function. Light in the gain region waveguide is transmitted through the feedback waveguide and then guided to the second end facet. The second end facet can reflect the light back to the feedback waveguide, so that the reflected light is transmitted through the feedback waveguide and the gain region waveguide and then guided to the first end facet. The first end facet has a reflection function and can reflect the light back to the gain region waveguide. Therefore, the light is reflected back and forth between the first end facet and the second end facet, forming a resonance. Furthermore, the first end facet has a transmission function, so that the obtained laser light with a narrow linewidth can be emitted through the first end facet.

[0006] In the laser provided in this embodiment of the present application, a feedback waveguide connected to the gain region waveguide is disposed, thereby increasing the equivalent cavity length of the laser, thereby reducing the resonant cavity loss and threshold gain of the laser, and compressing the laser linewidth. In addition, the feedback waveguide is monolithically integrated inside the laser, eliminating the need for an external cavity outside the laser cavity, thereby improving the integration density of the laser and reducing the material and processing costs of the laser.

[0007] In a possible implementation, the gain region waveguide may include an indium gallium arsenide phosphide (InGaAsP) material, and the feedback waveguide may include an indium gallium arsenide phosphide (InGaAsP) material. The gain region waveguide and the feedback waveguide may alternatively include other materials. This is not limited herein. Both the gain region waveguide and the feedback waveguide may be doped with impurities of a specific material, and the doping concentrations of the gain region waveguide and the feedback waveguide may be different, resulting in the gain region waveguide and the feedback waveguide having different refractive indices. The gain region waveguide and the feedback waveguide may also be arranged in a linear shape to provide good optical transmission.

[0008] In a specific implementation, the thickness of the gain region waveguide is 2 micrometers (μm) or less, and the thickness of the return waveguide is 2 μm or less. In this way, the thicknesses of the gain region waveguide and the return waveguide are equivalent to the wavelength of light, so that the light in the gain region waveguide and the return waveguide satisfies the wave-optics transmission law and the light can propagate inside the gain region waveguide and the return waveguide. Indeed, in some cases, the thicknesses of the gain region waveguide and the return waveguide may be slightly greater than 2 μm, as long as the light can propagate inside the gain region waveguide and the return waveguide. The thicknesses of the gain region waveguide and the return waveguide are not limited herein.

[0009] In a possible implementation, the laser provided in this embodiment of the present application further includes a substrate configured to support the gain region waveguide and the return waveguide, thereby allowing the gain region waveguide and the return waveguide to be integrated on the same substrate. Optionally, the substrate may include an indium phosphide material, an indium gallium arsenide aluminum material, or an indium gallium aluminum arsenide material. Indeed, the substrate may alternatively include other materials, which is not limited herein.

[0010] The laser in this embodiment of the present application may further include a gain material layer. The gain material layer may be disposed between the substrate and the gain region waveguide, and may be configured to emit light under the control of an electrical signal. In a specific implementation, the gain material layer may be disposed in a region corresponding to the gain region waveguide. In this way, light emitted from the gain material layer may be guided to the gain region waveguide. A passive material is used between the feedback waveguide and the substrate, and this passive material does not emit light under the control of an electrical signal, thereby avoiding the influence of spontaneous emission on the linewidth broadening of the laser.

[0011] In some embodiments of the present application, the return waveguide may be configured to adjust the phase of light propagated within the return waveguide under control of an electrical signal. The refractive index of the return waveguide may be adjusted by applying an electrical signal to the return waveguide to adjust the phase of the light propagated within the return waveguide, thereby implementing single longitudinal mode lasing of the laser. Further, the laser may include a first electrode. The first electrode may be disposed at a position corresponding to the return waveguide, and the first electrode may be configured to provide an electrical signal to the return waveguide.

[0012] In a possible implementation, the laser in this embodiment of the present application may further include an electrode layer. The electrode layer may include a first electrode, a second electrode, and a separation region. The separation region may be configured to separate the first electrode from the second electrode. The first electrode may be disposed at a position corresponding to the return waveguide, and the first electrode may be configured to provide an electrical signal to the return waveguide. The second electrode may be disposed at a position corresponding to the gain region waveguide, and the second electrode may be configured to provide an electrical signal to the gain material layer of the laser.

[0013] The first electrode and the second electrode are separated by a separation region, which allows electrical signals between the first electrode and the second electrode to be separated and thereby allows electrical signals to be applied to the feedback waveguide and the gain material layer separately. In a specific implementation, the separation region may be a line-shaped groove located between the first electrode and the second electrode. Indeed, in some cases, the separation region may alternatively be a hole penetrating the electrode layer, as long as the separation region can electrically separate the first electrode and the second electrode. The shape of the separation region is not limited herein. The depth of the separation region may be 0.5 μm to 0.8 μm. For example, the depth of the separation region may be 0.5 μm, 0.6 μm, or 0.8 μm. As long as the separation region can electrically separate the first electrode and the second electrode, the width of the separation region may be set based on actual requirements. The size of the separation region is not limited herein.

[0014] In a specific implementation, the first electrode and the second electrode may be made of a metal material. In the manufacturing process, the first electrode and the second electrode may be manufactured by using the same processing. Specifically, a metal layer may be first formed, and a region between the first electrode and the second electrode corresponding to the metal layer may be thinned or hollowed out by etching the metal layer to obtain a separation region for separating the first electrode and the second electrode.

[0015] In practical application, a ground point may be provided in the laser, and the first electrode may form a path to the ground point to supply a current signal to the return waveguide, and the second electrode may form a path to the ground point to supply a current signal to the gain material layer. In the operation process of the laser, the current applied to the first electrode may be different from the current applied to the second electrode. For example, the current applied to the first electrode may be 10 mA to 20 mA, and the current applied to the second electrode may be more than 100 mA. The current values ​​of the first electrode and the second electrode may be set based on practical requirements, which are not limited in this specification.

[0016] In a possible implementation, the laser in this embodiment of the present application may further include a grating structure. The grating structure may be disposed on a sidewall of the gain region waveguide. The grating structure may be configured to perform mode selection on the light propagated in the gain region waveguide. The diffraction effect of the grating structure is utilized to select a wavelength, thereby achieving a resonance effect on the light.

[0017] During the laser operation, the gain material layer can emit light within a specific spectral range under the control of an electrical signal, and the spectral range can be broadened. The gain region waveguide and the feedback waveguide do not emit light under the influence of an electrical signal. Therefore, the gain region waveguide and the feedback waveguide can serve as optical transmitters. Light emitted from the gain material layer is guided to the gain region waveguide. The light in the gain region waveguide passes through the feedback waveguide and is then guided to the second end facet. The second end facet can reflect the light back to the feedback waveguide, so that the reflected light passes through the feedback waveguide and the gain region waveguide and is then guided to the first end facet. The first end facet has a reflective function and can reflect the light back to the gain region waveguide. Therefore, the light is reflected back and forth between the first end facet and the second end facet, forming a resonance. In the process of light propagation between the first end face and the second end face, the grating structure can perform mode selection on the light propagated in the gain region waveguide, and the feedback waveguide can adjust the phase of the light propagated in the feedback waveguide. Under the action of the grating structure and the feedback waveguide, the linewidth of the light can be narrowed to obtain laser light with a narrow linewidth. Furthermore, the first end face has a transmission function, and the obtained laser light with a narrow linewidth can be output through the first end face.

[0018] In a possible implementation, the first end facet may include an anti-reflection coating, thereby providing both a reflective and a transmissive function. For example, the transmittance of the first end facet R1 may be approximately 90%, and the transmittance of the first end facet R1 may be set based on actual requirements. This is not a limitation of the present specification. The second end facet may include a high-reflection coating. For example, the reflectance of the second end facet R2 may be approximately 90%, and the reflectance of the second end facet R2 may be set based on actual requirements. This is not a limitation of the present specification. In this manner, light is reflected back and forth within the gain region waveguide and the feedback waveguide between the first and second end faces, and the formed laser light can be emitted through the first end facet.

[0019] Furthermore, the laser in this embodiment of the present application may further include a protective layer disposed on a side of the gain region waveguide and the return waveguide that is away from the substrate, and the electrode layer may be disposed on a side of the protective layer that is away from the substrate. By disposing the protective layer, the gain region waveguide, the return waveguide, and the diffraction grating structure can be protected to prevent damage to the gain region waveguide, the return waveguide, and the diffraction grating structure during subsequent manufacturing processes.

[0020] In some embodiments of the present application, the length of the grating structure may match the length of the gain region waveguide. In this way, the mode selection effect of the grating structure may be improved. In a possible implementation, the grating structure may be disposed on the side of the gain region waveguide that is far from the substrate. In a manufacturing process, the grating structure may be formed on the gain region waveguide after the gain region waveguide and the feedback waveguide are formed on the substrate. In this way, the gain region waveguide can be manufactured on a flat surface. Indeed, in some cases, the grating structure may be disposed on the side of the gain region waveguide that is closer to the substrate, or the grating structure may be disposed on both the side of the gain region waveguide that is closer to the substrate and the side of the gain region waveguide that is far from the substrate. This is not a limitation in the present specification.

[0021] In a possible implementation, the diffraction grating structure may include a first adjustment region and a phase-shift adjustment region. The lattice constant of the phase-shift adjustment region exceeds the lattice constant of the first adjustment region. The phase-shift adjustment region, which has a relatively large lattice constant, is provided to adjust the optical field distribution within the laser, thereby making the optical field distribution flatter and reducing the spatial hole burning effect, thereby improving the laser yield. After the feedback waveguide is disposed within the laser, the energy of the laser may be shifted to the side closer to the feedback waveguide. In this embodiment of the present application, the center point of the phase-shift adjustment region may be disposed on the side belonging to the central position of the diffraction grating structure and closer to the feedback waveguide. In this way, the phase-shift adjustment region is closer to the position where energy is concentrated within the laser, thereby making the optical field distribution flatter and more effectively preventing the spatial hole burning effect.

[0022] In a possible implementation, the diffraction grating structure can be divided into two regions: a first adjustment region and a phase-shift adjustment region. In another possible implementation, the diffraction grating structure can alternatively be divided into three regions. In addition to the first adjustment region and the phase-shift adjustment region, the diffraction grating structure can further include a second adjustment region. The phase-shift adjustment region can be disposed between the first adjustment region and the second adjustment region, and the lattice constant of the phase-shift adjustment region exceeds the lattice constant of the second adjustment region. In a specific implementation, the specific structure of the diffraction grating structure can be set based on actual requirements. This is not limited herein.

[0023] In a possible implementation, the length of the phase-shift adjustment region may be any value between 25% and 30% of the length of the diffraction grating structure (including the end values). Specifically, the length of the phase-shift adjustment region may be 25% or more of the length of the diffraction grating structure, and the length of the phase-shift adjustment region may be 30% or less of the length of the diffraction grating structure. For example, the length of the diffraction grating structure may be about 1000 μm, and the length of the phase-shift adjustment region P may be about 300 μm. In this way, the length of the phase-shift adjustment region may meet the requirement for adjusting the optical field distribution of the laser.

[0024] In a specific implementation, the length of the diffraction grating structure is normalized, and the end of the diffraction grating structure closest to the first end face is used as 0, and the end of the diffraction grating structure closest to the second end face is used as 1. The center point of the phase-shift adjustment region can be located at a position that is 0.7 to 0.8 (including the end point value) of the length of the diffraction grating structure. In this way, the position of the phase-shift adjustment region can be better matched to the position where energy is concentrated in the laser, and the spatial hole burning effect can be more effectively suppressed.

[0025] According to a second aspect, an embodiment of the present application further provides an optical module, which may include any of the lasers described above. A feedback waveguide connected to the gain region waveguide is disposed within the laser, thereby narrowing the linewidth of the laser light emitted by the laser. Therefore, the optical module including the laser has a good optical signal transmission effect. The optical module according to this embodiment of the present application may further include a silicon optical modulator. A first end face of the laser is connected to the silicon optical modulator. In practical application, a set current can be applied to the laser, causing the laser to output a constant optical intensity. The internal refractive index of the silicon optical modulator is adjusted, causing the laser light emitted by the laser to interfere with each other. The increase in optical coherence and the decrease in optical coherence are utilized to represent 0 or 1, thereby achieving optical signal transmission.

[0026] According to a third aspect, an embodiment of the present application further provides an apparatus, which may include any of the lasers described above. Since a feedback waveguide connected to the gain region waveguide is disposed in the laser, the linewidth of the laser emitted by the laser is narrowed, and therefore the performance of the apparatus including this laser is also improved.

[0027] In a possible implementation, the device may be any device in a cellular system related to the 3rd generation partnership project (3GPP), such as a 4G or 5G mobile communication system, or a future-oriented evolved system (such as a 6G mobile communication system). Alternatively, the device may be any device in an open radio access network (ORAN or ORAN) or a cloud radio access network (CRAN). Alternatively, the device may be any device in a communication system that integrates two or more of the above-mentioned systems.

[0028] Alternatively, the apparatus may be referred to as an access network device, a RAN entity, an access node, or the like, and forms part of a communication system to assist terminals in wireless access. In possible scenarios, the apparatus may be a base station, an evolved nodeB (eNodeB), an access point (AP), a transmission reception point (TRP), a next-generation nodeB (gNB), a next-generation nodeB in a sixth-generation (6G) mobile communication system, a base station in a future mobile communication system, an access node in a Wi-Fi system, or the like. The apparatus may be a macro base station, a micro base station, an indoor base station, a relay node, a donor node, or a radio controller in a CRAN scenario. Optionally, the apparatus may alternatively be a server, a wearable device, a vehicle, an in-vehicle device, or the like. For example, the access network apparatus in vehicle-to-everything (V2X) technology may be a road side unit (RSU).

[0029] In another possible scenario, the apparatus may be a central unit (CU), a distributed unit (DU), a CU control plane (CP), a CU user plane (UP), a radio unit (RU), or the like. The CU and DU may be located separately or may be included in the same network element, for example, a baseband unit (BBU). The RU may be included in a radio frequency device or may be included in a radio frequency unit, for example, a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH).

[0030] In different systems, the CU (or CU-CP and CU-UP), DU, or RU may have different names, but those skilled in the art will understand their meanings. For example, in an ORAN system, the CU may alternatively be referred to as an 0-CU (i.e., open CU), the DU may alternatively be referred to as an 0-DU, the CU-CP may alternatively be referred to as an 0-CU-CP, the CU-UP may alternatively be referred to as an 0-CU-UP, and the RU may alternatively be referred to as an 0-RU. For ease of explanation, this application uses the CU, CU-CP, CU-UP, DU, and RU as examples. Any one of the CU (or CU-CP or CU-UP), DU, and RU in this application may be implemented by using a software module, a hardware module, or a combination thereof.

[0031] In a specific implementation, the device in this embodiment of the present application may alternatively be another device including a laser, and the type of device in this embodiment of the present application is not limited herein.

[0032] In some implementations of the present application, the device may further include an optical module, which includes a laser. In other words, the laser may be integrated into the optical module. In a specific implementation, the laser may alternatively be located in another component of the device. For example, the laser may be located in a baseband processing unit (BBU). Optionally, the laser may be directly integrated into a baseband board of the BBU.

[0033] In some embodiments of the present application, the laser can be disposed on the circuit board of the device. For example, the laser can be directly integrated on the circuit board, or the laser can be plugged onto the circuit board, or can be disposed based on actual requirements. In this way, the cost of the optical module is saved and the size of the device is reduced. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 1 illustrates a laser structure according to an embodiment of the present application. [Figure 2] (1) and (2) are distribution diagrams showing the internal optical field of a laser, respectively. [Figure 3] 1A and 1B are diagrams illustrating configurations of diffraction grating structures according to embodiments of the present application; [Figure 4] 10A-10C illustrate another configuration of a diffraction grating structure according to an embodiment of the present application. [Figure 5] FIG. 10 illustrates the location of phase shift adjustment regions according to an embodiment of the present application. [Figure 6] 10A-10C illustrate alternative locations of phase shift adjustment regions according to embodiments of the present application. [Figure 7] 1 is a diagram showing the configuration of a DFB laser according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0035] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application is described in more detail below with reference to the accompanying drawings. The reference numerals in the accompanying drawings in the embodiments of the present application are as follows (see column "Description of numerals"):

[0036] It should be noted that in the accompanying drawings of this application, the same reference numerals represent the same or similar components. Therefore, redundant descriptions thereof will be omitted. The expressions of positions and directions in this application are described using the accompanying drawings as examples. However, changes may be made as necessary, and all such changes are within the scope of protection of this application. The accompanying drawings in this application are merely used to illustrate relative positional relationships and do not represent actual scales.

[0037] Optical communication technology can also be applied in wireless scenarios. Optical communication technology has high requirements for the linewidth of lasers. For example, based on quadrature amplitude modulation (QAM16), the mainstream modulation method in current communication technology, the laser linewidth needs to be less than 5 megahertz (MHz). The higher the modulation frequency, the higher the linewidth requirement. Furthermore, narrowing the linewidth also helps reduce the power consumption of optical digital signal processing (oDSP). However, it is difficult for current lasers to meet the linewidth requirements of optical communication technology.

[0038] Based on this, in order to narrow the linewidth of the laser, embodiments of the present application provide a laser, an optical module, and an apparatus. The laser in the embodiments of the present application can be various types of lasers. For example, the laser can be a distribution feedback laser (DFB). The laser can be applied to optical communication scenarios, such as wireless short-range optical communication scenarios. The linewidth of the laser in the embodiments of the present application can be less than 1 MHz, which can meet the wireless transmission requirements for a transmission distance of about 10 kilometers (km).

[0039] FIG. 1 is a diagram illustrating a laser structure according to an embodiment of the present application. As shown in FIG. 1, the laser provided in an embodiment of the present application may include a gain region waveguide 11, a feedback waveguide 12, a first end face R1, and a second end face R2. The gain region waveguide 11 and the feedback waveguide 12 are disposed between the first end face R1 and the second end face R2, with the end of the gain region waveguide 11 connected to the end of the feedback waveguide 12, and the feedback waveguide 12 being disposed on the side belonging to the gain region waveguide 11 and close to the second end face R2. In FIG. 1, a dashed line W is located between the gain region waveguide 11 and the feedback waveguide 12. Specifically, the gain region waveguide 11 is disposed on the side belonging to the dashed line W and close to the first end face R1, and the feedback waveguide 12 is disposed on the side belonging to the dashed line W and close to the second end face R2. The first end face R1 and the second end face R2 are configured to transmit light into the gain region waveguide 11 and the feedback waveguide 12, and the first end face R1 is configured to transmit laser light.

[0040] The laser in this embodiment of the present application may be a distributed feedback laser. In specific implementation, the laser in this embodiment of the present application may alternatively be another type of laser, which is not limited herein.

[0041] In this embodiment of the present application, both the gain region waveguide 11 and the feedback waveguide 12 are waveguides having an optical transmission function. Light in the gain region waveguide 11 passes through the feedback waveguide 12 and is then guided to the second end facet R2. The second end facet R2 can reflect the light back to the feedback waveguide 12, so that the reflected light passes through the feedback waveguide 12 and the gain region waveguide 11 and is then guided to the first end facet R1. The first end facet R1 has a reflection function and can reflect the light back to the gain region waveguide 11. Therefore, the light is reflected back and forth between the first end facet R1 and the second end facet R2, forming a resonance. Furthermore, the first end facet R1 has a transmission function, so that the acquired laser light with a narrow linewidth can be emitted through the first end facet R1.

[0042] In the laser provided in this embodiment of the present application, a feedback waveguide connected to the gain region waveguide is disposed, thereby increasing the equivalent cavity length of the laser, thereby reducing the resonant cavity loss and threshold gain of the laser, and compressing the laser linewidth. In addition, the feedback waveguide is monolithically integrated inside the laser, eliminating the need for an external cavity outside the laser cavity, thereby improving the integration density of the laser and reducing the material and processing costs of the laser.

[0043] In this embodiment of the present application, the linewidth compression level of the feedback waveguide is related to at least two factors. One factor is the energy value of the feedback light, specifically, the power of the light reflected back to the gain region waveguide, and the other factor is the optical path length of the light outside the gain region waveguide. The second end face has a reflective function, and the light in the feedback waveguide is reflected back when it reaches the second end face. The feedback light may refer to the light reflected by the second end face and propagating back to the gain region waveguide through the feedback waveguide. The longer the length of the feedback waveguide, the longer the optical path length of the light in the feedback waveguide, and the transmission distance of the light in the feedback waveguide is twice the length of the feedback waveguide.

[0044] In a possible implementation, the gain region waveguide 11 may include an indium gallium arsenide phosphide (InGaAsP) material, and the feedback waveguide 12 may include an indium gallium arsenide phosphide (InGaAsP) material. The gain region waveguide 11 and the feedback waveguide 12 may alternatively include other materials. This is not limited herein. Both the gain region waveguide 11 and the feedback waveguide 12 may be doped with impurities of a specific material, and the gain region waveguide 11 and the feedback waveguide 12 have different doping concentrations, which causes the gain region waveguide 11 and the feedback waveguide 12 to have different refractive indices. The gain region waveguide 11 and the feedback waveguide 12 may also be arranged in a linear shape to provide good optical transmission.

[0045] In a specific implementation, the thickness of the gain region waveguide may be 2 micrometers (μm) or less, and the thickness of the return waveguide may be 2 μm or less. In this way, the thicknesses of the gain region waveguide and the return waveguide are comparable to the wavelength of light, so that the light in the gain region waveguide and the return waveguide satisfies the wave optics transmission law and can propagate inside the gain region waveguide and the return waveguide.

[0046] In a possible implementation, the laser provided in this embodiment of the present application may further include a substrate 10. The substrate 10 is configured to support the gain region waveguide 11 and the return waveguide 12, thereby allowing the gain region waveguide 11 and the return waveguide 12 to be integrated on the same substrate 10. Optionally, the substrate 10 may include an indium phosphide material, an indium gallium arsenide aluminum material, or an indium gallium aluminum arsenide material. Certainly, the substrate 10 may alternatively include other materials, which is not limited herein.

[0047] Still referring to FIG. 1 , the laser in this embodiment of the present application may further include a gain material layer 101. The gain material layer 101 is disposed between the substrate 10 and the gain region waveguide 11, and the gain material layer 101 may be configured to emit light under the control of an electrical signal. In a specific implementation, the gain material layer 10 may be disposed in a region corresponding to the gain region waveguide 11. For example, as shown in FIG. 1 , the gain material layer 10 may be disposed on the side belonging to the dashed line W and close to the first end facet R1. In this way, the light emitted from the gain material layer 101 may be guided to the gain region waveguide 11. A passive material is used between the feedback waveguide 12 and the substrate 10, and this passive material does not emit light under the control of an electrical signal, thereby avoiding the influence of spontaneous emission on the linewidth broadening of the laser.

[0048] In some embodiments of the present application, the return waveguide 12 may be configured to adjust the phase of light propagated within the return waveguide 12 under control of an electrical signal. The refractive index of the return waveguide 12 may be adjusted by applying an electrical signal to the return waveguide 12 to adjust the phase of the light propagated within the return waveguide 12, thereby causing the laser to perform single longitudinal mode lasing. Further, the laser may include a first electrode 15. The first electrode 15 is disposed at a position corresponding to the return waveguide 12, and the first electrode 15 may be configured to provide an electrical signal to the return waveguide 12.

[0049] 1 , the laser in this embodiment of the present application may further include an electrode layer. The electrode layer may include a first electrode 15, a second electrode 16, and a separation region 17. The separation region 17 may be configured to separate the first electrode 15 from the second electrode 16. The first electrode 15 is disposed at a position corresponding to the return waveguide 12, and the first electrode 15 may be configured to provide an electrical signal to the return waveguide 12. The second electrode 16 is disposed at a position corresponding to the gain region waveguide 11, and the second electrode 16 may be configured to provide an electrical signal to the gain material layer 101 of the laser.

[0050] The first electrode 15 and the second electrode 16 are separated by a separation region 17, which separates the electrical signals between the first electrode 15 and the second electrode 16 and allows the electrical signals to be applied to the return waveguide 12 and the gain material layer 101 separately. In a specific implementation, the separation region 17 may be a line-shaped groove located between the first electrode 15 and the second electrode 16. Indeed, in some cases, the separation region 17 may alternatively be a hole penetrating the electrode layer, as long as the separation region 17 can electrically separate the first electrode 15 and the second electrode 16. The shape of the separation region 17 is not limited herein. The depth of the separation region 17 may be 0.5 μm to 0.8 μm. For example, the depth of the separation region 17 may be 0.5 μm, 0.6 μm, or 0.8 μm. The width of the separation region 17 may be set according to actual requirements, as long as the separation region 17 can electrically separate the first electrode 15 and the second electrode 16. The size of the separation region 17 is not limited herein.

[0051] In a specific implementation, the first electrode 15 and the second electrode 16 may be made of a metal material. In the manufacturing process, the first electrode 15 and the second electrode 16 may be manufactured by using the same processing process. Specifically, a metal layer may be first formed, and a region between the first electrode 15 and the second electrode 16, which corresponds to the metal layer, may be thinned or hollowed out by etching the metal layer to obtain a separation region for separating the first electrode and the second electrode.

[0052] In practical application, a ground point may be provided on the laser, and the first electrode 15 forms a path to the ground point to supply a current signal to the return waveguide 12, and the second electrode 16 forms a path to the ground point to supply a current signal to the gain material layer 101. In the operation process of the laser, the current applied to the first electrode 15 may be different from the current applied to the second electrode 16. For example, the current applied to the first electrode 15 may be 10 mA to 20 mA, and the current applied to the second electrode 16 may be more than 100 mA. The current values ​​of the first electrode 15 and the second electrode 16 may be set based on practical requirements, which are not limited in this specification.

[0053] In a possible implementation, the laser in this embodiment of the present application may further include a grating structure 13. The grating structure 13 may be disposed on a sidewall of the gain region waveguide 11. The grating structure 13 may be configured to perform mode selection on the light propagated in the gain region waveguide 11. A resonance effect on the light is obtained by selecting the wavelength using the diffraction effect of the grating structure 13.

[0054] During the laser operation, the gain material layer 101 can emit light within a specific spectral range under the control of an electrical signal, and the spectral range can be broadened. The gain region waveguide 11 and the feedback waveguide 12 do not emit light under the influence of an electrical signal. Therefore, the gain region waveguide 11 and the feedback waveguide 12 can play the role of optical transmission. The light emitted from the gain material layer 101 is guided to the gain region waveguide 11. The light in the gain region waveguide 11 passes through the feedback waveguide 12 and is then guided to the second end face R2. The second end face R2 can reflect the light back to the feedback waveguide 12, so that the reflected light passes through the feedback waveguide 12 and the gain region waveguide 11 and is then guided to the first end face R1. The first end face R1 has a reflective function and can reflect the light back to the gain region waveguide 11. Therefore, the light is reflected back and forth between the first end face R1 and the second end face R2, forming a resonance. In the process of light propagation between the first end face R1 and the second end face R2, the diffraction grating structure 13 can perform mode selection on the light propagating in the gain region waveguide 11, and the feedback waveguide 12 can adjust the phase of the light propagating in the feedback waveguide 12. Under the action of the diffraction grating structure 13 and the feedback waveguide 12, the linewidth of the light can be narrowed to obtain laser light with a narrow linewidth. Furthermore, the first end face R1 has a transmission function, and the obtained laser light with a narrow linewidth can be output through the first end face R1.

[0055] In a possible implementation, the first end face R1 may include an anti-reflection coating, thereby providing both a reflective and a transmissive function. For example, the transmittance of the first end face R1 may be approximately 90% and may be set based on actual requirements. This is not a limitation of the present specification. The second end face R2 may include a high-reflection coating. For example, the reflectance of the second end face R2 may be approximately 90% and may be set based on actual requirements. This is not a limitation of the present specification. In this manner, light is reflected back and forth within the gain region waveguide 11 and the feedback waveguide 12 between the first end face R1 and the second end face R2, and the formed laser light can be emitted through the first end face R1.

[0056] Moreover, the laser in this embodiment of the present application may further include a protective layer 14 arranged on the side of the gain region waveguide 11 and the feedback waveguide 12 that belongs to the substrate 10 and is remote from the substrate 10, and the electrode layer may be arranged on the side that belongs to the protective layer 14 and is remote from the substrate 10. By providing the protective layer 14, the gain region waveguide 11, the feedback waveguide 12, and the diffraction grating structure 13 can be protected to prevent damage to the gain region waveguide 11, the feedback waveguide 12, and the diffraction grating structure 13 during subsequent manufacturing processes.

[0057] Still referring to FIG. 1 , in some embodiments of the present application, the length of the grating structure 13 may match the length of the gain region waveguide 11. In this way, the mode selection effect of the grating structure 13 may be good. In a possible implementation, the grating structure 13 may be disposed on the side belonging to the gain region waveguide 11, away from the substrate 10. In a manufacturing process, the gain region waveguide 11 and the feedback waveguide 12 are formed on the substrate 10, and then the grating structure 13 may be formed on the gain region waveguide 11. In this way, the gain region waveguide 11 can be manufactured on a flat surface. Indeed, in some cases, the grating structure 13 may alternatively be disposed on the side belonging to the gain region waveguide 11, closer to the substrate 10, or the grating structure 13 may be disposed on both the side belonging to the gain region waveguide 11, closer to the substrate 10, and the side belonging to the gain region waveguide 11, away from the substrate 10. This is not a limitation in the present specification.

[0058] FIG. 2 is a diagram showing the internal optical field of a laser. (1) in FIG. 2 is a diagram showing the optical field of a laser without a feedback waveguide. (2) in FIG. 2 is a diagram showing the optical field of a laser with a feedback waveguide. In (1) and (2) in FIG. 2, the horizontal axis represents the position from the first end face to the second end face within the laser, with larger values ​​on the abscissa representing positions closer to the second end face. The vertical axis represents the energy density at various positions within the laser. As shown in (1) in FIG. 2, in a laser without a feedback waveguide, energy is primarily concentrated at the center of the laser. As shown in (2) in FIG. 2, in an embodiment of the present application, after a feedback waveguide is placed within the laser, energy is primarily concentrated at the center of the right side of the laser (the side closest to the second end face). That is, the laser's energy shifts to the side closer to the feedback waveguide.

[0059] As can be seen from FIG. 2, the energy in the laser is mainly concentrated at one location, which results in a relatively large optical consumption at the location where the energy is concentrated. As a result, the single-mode characteristics of the laser are impaired, affecting the laser yield. This phenomenon is called the spatial hole burning effect. The yield may refer to the percentage of lasers that meet the requirements in a batch of lasers. To suppress the spatial hole burning effect in the laser, the specific structure of the diffraction grating structure is improved in the embodiment of the present application. The details are as follows:

[0060] FIG. 3 is a diagram illustrating the configuration of a diffraction grating structure according to one embodiment of the present application. As shown in FIG. 3, the diffraction grating structure 13 may include a first adjustment region Q1 and a phase-shift adjustment region P. The lattice constant of the phase-shift adjustment region P is greater than that of the first adjustment region Q1. The phase-shift adjustment region P, which has a relatively large lattice constant, is provided to adjust the optical field distribution within the laser, thereby flattening the optical field distribution and reducing the spatial hole burning effect, thereby improving the laser yield. After the feedback waveguide is disposed within the laser, the energy of the laser may be shifted to the side closer to the feedback waveguide. In this embodiment of the present application, the center point of the phase-shift adjustment region P may be located on the side belonging to the central position of the diffraction grating structure 13, closer to the feedback waveguide. In this way, the phase-shift adjustment region P is closer to the position where energy is concentrated within the laser, thereby flattening the optical field distribution and more effectively preventing the spatial hole burning effect.

[0061] In a possible implementation, the diffraction grating structure 13 can be divided into two regions: a first adjustment region Q1 and a phase-shift adjustment region P. FIG. 4 illustrates another configuration of a diffraction grating structure according to an embodiment of the present invention. As shown in FIG. 4, in another possible implementation, the diffraction grating structure 13 can alternatively be divided into three regions. In addition to the first adjustment region Q1 and the phase-shift adjustment region P, the diffraction grating structure 13 can further include a second adjustment region Q2. The phase-shift adjustment region P can be disposed between the first adjustment region Q1 and the second adjustment region Q2, and the lattice constant of the phase-shift adjustment region P can be greater than the lattice constant of the second adjustment region Q2. In a specific implementation, the specific structure of the diffraction grating structure 13 can be set based on actual requirements. This is not limited to this specification.

[0062] In a possible implementation, the length of the phase-shift adjustment region P may be any value between 25% and 30% (including end values) of the length of the diffraction grating structure 13. Specifically, the length of the phase-shift adjustment region P may be 25% or more of the length of the diffraction grating structure 13, and the length of the phase-shift adjustment region P may be 30% or less of the length of the diffraction grating structure 13. For example, the length of the diffraction grating structure 13 may be about 1000 μm, and the length of the phase-shift adjustment region P may be about 300 μm. In this way, the length of the phase-shift adjustment region P may meet the requirement for adjusting the optical field distribution of the laser.

[0063] FIG. 5 illustrates the position of a phase-shift adjustment region according to an embodiment of the present application. FIG. 6 illustrates another position of a phase-shift adjustment region according to an embodiment of the present application. Referring to FIGS. 5 and 6, the length of the diffraction grating structure 13 is normalized, with the end of the diffraction grating structure 13 closest to the first end face R1 being used as 0, and the end of the diffraction grating structure 13 closest to the second end face (i.e., the position of the dashed line W) being used as 1. The center point of the phase-shift adjustment region P is located at a position that is 0.7 to 0.8 (including the end values) of the length of the diffraction grating structure 13. In this way, the position of the phase-shift adjustment region P can be better adapted to the position where energy is concentrated in the laser, and the spatial hole burning effect can be more effectively suppressed. For example, in FIG. 5, the center point of the phase-shift adjustment region P is located at a position that is 0.7 of the length of the diffraction grating structure 13. An example in which the length of the diffraction grating structure 13 is approximately 1000 μm is still used. The phase-shift adjustment region P may be located at a position between 550 μm and 850 μm into the length of the diffraction grating structure 13. As another example, in FIG. 6, the center point of the phase-shift adjustment region P is located at a position that is 0.8 of the length of the diffraction grating structure 13. We will still use the example where the length of the diffraction grating structure 13 is about 1000 μm. The phase-shift adjustment region P may be located at a position between 650 μm and 950 μm into the length of the diffraction grating structure 13.

[0064] In the laser provided in this embodiment of the present application, a feedback waveguide is provided, which increases the equivalent cavity length of the laser and thereby compresses the linewidth of the laser. In addition, the feedback waveguide is integrated inside the laser, eliminating the need for an external cavity outside the laser cavity. This improves the integration density of the laser, reduces the volume of the laser, and also reduces the material and processing costs of the laser.

[0065] 7 is a diagram showing the structure of a DFB laser according to an embodiment of the present application. As shown in FIG. 7, the DFB laser in this embodiment of the present application may include structures such as a laser diode (PD), a rear mirror, a diffraction grating region and a gain region, a front mirror, an isolator, a coupling prism, and a thermoelectric cooler (TEC). The DFB laser in this embodiment of the present application has a simple structure and a small volume.

[0066] Based on a similar technical concept, an embodiment of the present application further provides an optical module. The optical module in this embodiment of the present application may include any of the lasers described above. A feedback waveguide connected to the gain region waveguide is disposed within the laser, thereby narrowing the linewidth of the laser emitted by the laser. Therefore, the optical module including the laser has a good optical signal transmission effect. Furthermore, the optical module in this embodiment of the present application may include a silicon optical modulator. A first end face of the laser is connected to the silicon optical modulator. In practical application, a set current can be applied to the laser, causing the laser to output a constant optical intensity. The internal refractive index of the silicon optical modulator is adjusted, causing the laser light emitted by the laser to interfere with each other. The increase in optical coherence and the decrease in optical coherence are utilized to represent 0 or 1, thereby achieving optical signal transmission.

[0067] Based on the same technical concept, an embodiment of the present application further provides an apparatus, which may include any of the lasers described above. Since a feedback waveguide connected to the gain region waveguide is disposed in the laser, the linewidth of the laser emitted by the laser is narrowed, thereby improving the performance of the apparatus including the laser.

[0068] In a possible implementation, the device may be any device in a cellular system related to the 3rd generation partnership project (3GPP), such as a 4G or 5G mobile communication system, or a future-oriented evolved system (such as a 6G mobile communication system). Alternatively, the device may be any device in an open radio access network (ORAN or ORAN) or a cloud radio access network (CRAN). Alternatively, the device may be any device in a communication system that integrates two or more of the above-mentioned systems.

[0069] Alternatively, the device may be referred to as an access network device, a RAN entity, an access node, or the like, and forms part of a communication system to assist terminals in wireless access. In possible scenarios, the device may be a base station, an evolved nodeB (eNodeB), an access point (AP), a transmission reception point (TRP), a next-generation nodeB (gNB), a next-generation nodeB in a sixth-generation (6G) mobile communication system, a base station in a future mobile communication system, an access node in a Wi-Fi system, or the like. The device may be a macro base station, a micro base station, an indoor base station, a relay node, a donor node, or a radio controller in a CRAN scenario. Optionally, the device may alternatively be a server, a wearable device, a vehicle, an in-vehicle device, or the like. For example, the access network device in vehicle-to-everything (V2X) technology may be a road side unit (RSU).

[0070] In another possible scenario, the device may be a central unit (CU), a distributed unit (DU), a CU control plane (CP), a CU user plane (UP), a radio unit (RU), or the like. The CU and DU may be located separately or may be included in the same network element, such as a baseband unit (BBU). The RU may be included in a radio frequency device or radio frequency unit, such as a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH).

[0071] In different systems, the CU (or CU-CP and CU-UP), DU, or RU may have different names, but those skilled in the art will understand their meanings. For example, in an ORAN system, the CU may alternatively be referred to as an 0-CU (i.e., open CU), the DU may alternatively be referred to as an 0-DU, the CU-CP may alternatively be referred to as an 0-CU-CP, the CU-UP may alternatively be referred to as an 0-CU-UP, and the RU may alternatively be referred to as an 0-RU. For ease of explanation, this application uses the CU, CU-CP, CU-UP, DU, and RU as examples. Any one of the CU (or CU-CP or CU-UP), DU, and RU in this application may be implemented by using a software module, a hardware module, or a combination thereof.

[0072] In a specific implementation, the device in this embodiment of the present application may alternatively be another device including a laser, and the type of device in this embodiment of the present application is not limited herein.

[0073] In some embodiments of the present application, the device may further include an optical module, which includes a laser. In other words, the laser may be integrated into the optical module. In a specific implementation, the laser may alternatively be located in another component of the device. For example, the laser may be located in a baseband processing unit (BBU). Optionally, the laser may be directly integrated into a baseband board of the BBU.

[0074] In some embodiments of the present application, the laser can be disposed on the circuit board of the device. For example, the laser can be directly integrated on the circuit board, or the laser can be plugged onto the circuit board, or can be disposed based on actual requirements. In this way, the cost of the optical module is saved and the size of the device is reduced.

[0075] Although exemplary embodiments of the present application have been described, those skilled in the art can make changes and modifications to these embodiments after understanding the basic concepts of the present invention. Therefore, it is intended that the following claims be interpreted to cover the preferred embodiments and all changes and modifications that fall within the scope of this application.

[0076] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present application without departing from the spirit and scope of the embodiments of the present application, in which case the present application intends to cover these modifications and variations in the embodiments of the present application as long as they fall within the scope of protection defined by the following claims and their equivalent technologies. [Explanation of symbols]

[0077] 10 Substrate 11 Gain-domain waveguide 12 Feedback waveguide 13 Diffraction grating structure 14 Protective layer 15 First electrode 16 Second electrode 101 Gain material layer R1 First end face R2 Second end face P Phase shift adjustment area Q1 First adjustment area Q2 Second adjustment area

Claims

1. 1. A laser comprising a gain region waveguide, a feedback waveguide, a first end facet, and a second end facet, the gain region waveguide and the feedback waveguide are disposed between the first end face and the second end face, an end of the gain region waveguide is connected to an end of the feedback waveguide, and the feedback waveguide is disposed on a side belonging to the gain region waveguide and close to the second end face; the first end facet and the second end facet are configured to transmit light into the gain region waveguide and the return waveguide, and the first end facet is configured to transmit laser light. Laser.

2. 10. The laser of claim 1, wherein the return waveguide is configured to adjust the phase of light propagated within the return waveguide under control of an electrical signal.

3. further comprising a first electrode; the first electrode is disposed at a position corresponding to the return waveguide, and the first electrode is configured to supply an electrical signal to the return waveguide.

3. The laser of claim 2.

4. Further comprising an electrode layer; the electrode layer includes the first electrode, a second electrode, and a separation region; the separation region is configured to separate the first electrode from the second electrode; the first electrode is disposed at the position corresponding to the return waveguide, and the first electrode is configured to supply an electrical signal to the return waveguide; the second electrode is disposed at a position corresponding to the gain region waveguide, the second electrode being configured to provide an electrical signal to a gain material layer of the laser.

4. A laser according to any one of claims 1 to 3.

5. 5. The laser of claim 4 wherein the isolation region has a depth of 0.5 micrometers to 0.8 micrometers.

6. Further comprising a diffraction grating structure, the grating structure is disposed on a sidewall of the gain region waveguide, the grating structure being configured to perform mode selection on light propagated within the gain region waveguide.

41. A laser according to any one of claims 41 to 5.

7. the grating structure includes a first tuning region and a phase-shift tuning region; a lattice constant of the phase shift adjustment region exceeds a lattice constant of the first adjustment region; a center point of the phase shift adjustment region is located on a side belonging to a central position of the diffraction grating structure and on a side close to the feedback waveguide; 7. The laser of claim 6.

8. 8. The laser of claim 7, wherein the length of the phase-shift tuning region is 25% to 30% of the length of the grating structure.

9. 9. The laser of claim 7, wherein the length of the diffraction grating structure is normalized, an end of the diffraction grating structure that is closest to the first end face is used as 0, an end of the diffraction grating structure that is closest to the second end face is used as 1, and the center point of the phase-shift adjustment region is located at a position that is 0.7 to 0.8 of the length of the diffraction grating structure.

10. 10. The laser of claim 6, wherein the length of the grating structure matches the length of the gain region waveguide.

11. Further comprising a substrate; the substrate is configured to support the gain region waveguide and the return waveguide; the grating structure is disposed on a side of the gain region waveguide that is away from the substrate; 10. A laser according to any one of claims 6 to 9.

12. further comprising the gain material layer; the gain material layer is disposed between the substrate and the gain region waveguide, the gain material layer being configured to emit light under control of an electrical signal; 12. The laser of claim 11.

13. 13. The laser of claim 1, wherein the gain region waveguide has a thickness of 2 micrometers or less and the feedback waveguide has a thickness of 2 micrometers or less.

14. 14. The laser of claim 1, wherein the first facet includes an anti-reflective coating and the second facet includes a highly reflective coating.

15. 15. The laser of claim 1, wherein the laser is a distributed feedback laser.

16. An optical module comprising a laser according to any one of claims 1 to 15.

17. 17. The optical module of claim 16, further comprising a silicon optical modulator, wherein a first end face of the laser is connected to the silicon optical modulator.

18. 16. Apparatus comprising a laser according to any one of claims 1 to 15.

19. The device of claim 18, wherein the device is a wireless unit or a distributed unit.

20. further comprising an optical module; the optical module includes the laser; 20. Apparatus according to claim 18 or 19.

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