Lasers, optical modules, and devices
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- HUAWEI TECH CO LTD
- Filing Date
- 2022-12-23
- Publication Date
- 2026-08-04
Smart Images
Figure 0007900614000001 
Figure 0007900614000002 
Figure 0007900614000003
Abstract
Description
Technical Field
[0001] This application relates to the field of communication technologies, and in particular, to lasers, optical modules, and devices.
Background Art
[0002] With the gradual increase of future bandwidth, optical communication technology has gradually been widely applied, and optical communication technology may also be applied to wireless scenarios. However, optical communication technology places higher requirements on the linewidth of lasers. For example, based on quadrature amplitude modulation (QAM16), which is the mainstream modulation method in current communication technologies, the linewidth of the laser needs to be less than 5 MHz. The higher the modulation frequency, the higher the requirement for the linewidth. Furthermore, the narrower the linewidth, the more helpful it is for reducing the power consumption of optical digital signal processing (oDSP). Therefore, how to narrow the linewidth of the laser is a technical problem that needs to be solved urgently.
Summary of the Invention
[0003] Embodiments of this application provide a laser, an optical module, and a device for narrowing the linewidth of a laser.
[0004] According to a first aspect, an embodiment of this application provides a laser. This laser can be various types of lasers. For example, this laser may be a distributed feedback laser (DFB). The laser in this embodiment of this application may include a gain region waveguide, a feedback waveguide, a first end face, and a second end face. The gain region waveguide and the feedback waveguide are arranged between the first end face and the second end face, and the end of the gain region waveguide is connected to the end of the feedback waveguide. The feedback waveguide is on the of side amongThe first end face is positioned on the side adjacent to the second end face. The first and second end faces are configured to transmit light into the gain region waveguide and the feedback waveguide, and the first end face is configured to transmit laser light.
[0005] In this embodiment of the present application, both the gain-domain waveguide and the feedback waveguide are waveguides having optical transmission capabilities. Light in the gain-domain waveguide is guided to a second end face after passing through the feedback waveguide. The second end face can reflect the light to the feedback waveguide, thereby guiding the reflected light to the first end face after passing through the feedback waveguide and the gain-domain waveguide. The first end face has a reflective function and can reflect the light to the gain-domain waveguide. As a result, the light is reflected back and forth between the first and second end faces, forming a resonance. Furthermore, the first end face has a transmitting function, and the acquired laser light with a narrow linewidth can be emitted through the first end face.
[0006] In the laser provided in this embodiment of the present application, a feedback waveguide is arranged connected to the gain region waveguide, thereby increasing the equivalent resonator length of the laser, reducing the laser's resonant cavity loss and threshold gain, and compressing the laser's linewidth. Furthermore, the feedback waveguide is monolithically integrated inside the laser, eliminating the need to arrange an external resonator outside the laser's resonator. This improves the integration density of the laser and reduces the material and processing costs of the laser.
[0007] In possible implementations, the gain-domain waveguide may contain indium gallium arsenide phosphide (InGaAsP) material, and the feedback waveguide may contain indium gallium arsenide phosphide (InGaAsP) material. Indeed, the gain-domain waveguide and the feedback waveguide may, alternatively, contain other materials. This is not limited herein. Impurities of a specific material may be implanted into both the gain-domain waveguide and the feedback waveguide, resulting in different doping concentrations in the gain-domain waveguide and the feedback waveguide, thereby giving them different refractive indices. Furthermore, the gain-domain waveguide and the feedback waveguide may be arranged in a linear configuration to achieve good optical transmission functionality.
[0008] In specific implementations, the thickness of the gain-domain waveguide is 2 micrometers (μm) or less, and the thickness of the feedback waveguide is 2 μm or less. In this way, the thicknesses of the gain-domain waveguide and the feedback waveguide are equivalent to the wavelength of light, thereby satisfying the wave-optic transmission law for light within the gain-domain waveguide and the feedback waveguide, and allowing the light to propagate through the interior of the gain-domain waveguide and the feedback waveguide. Indeed, in some cases, the thicknesses of the gain-domain waveguide and the feedback waveguide may be slightly greater than 2 μm, as long as the light can propagate through them. The thicknesses of the gain-domain waveguide and the feedback waveguide are not limited herein.
[0009] In possible implementations, the laser provided in these embodiments of the present application further includes a substrate configured to support a gain-domain waveguide and a feedback waveguide, thereby enabling the integration of the gain-domain waveguide and the feedback waveguide onto the same substrate. Optionally, the substrate may include an indium phosphate material, an indium gallium arsenide aluminum material, or an indium gallium aluminum arsenide material. Indeed, the substrate may alternatively include other materials, but is not limited herein.
[0010] The laser in this embodiment of the application may further include a gain material layer. The gain material layer is placed between the substrate and the gain region waveguide and may be configured to emit light under control by an electrical signal. In specific implementations, the gain material layer may be placed in a region corresponding to the gain region waveguide. In this way, light emitted from the gain material layer can be guided into the gain region waveguide. A passive material is used between the feedback waveguide and the substrate, and since this passive material does not emit light under control by an electrical signal, it avoids the influence of spontaneous emission on the laser linewidth expansion.
[0011] In some embodiments of this application, the feedback waveguide may be configured to adjust the phase of light propagated within the feedback waveguide under control by an electrical signal. The refractive index of the feedback waveguide can be adjusted by applying an electrical signal to the feedback waveguide to adjust the phase of light propagated within the feedback waveguide, thereby enabling single-longitudinal-mode laser oscillation of the laser. Furthermore, the laser may include a first electrode. The first electrode may be positioned corresponding to the feedback waveguide and may be configured to supply an electrical signal to the feedback waveguide.
[0012] In possible implementations, the laser in this embodiment of the application may further comprise 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 positioned to correspond to a feedback waveguide and configured to supply an electrical signal to the feedback waveguide. The second electrode may be positioned to correspond to a gain region waveguide and configured to supply an electrical signal to the gain material layer of the laser.
[0013] The first and second electrodes are separated by a separation region, which allows for the separation of the electrical signals between the first and second electrodes, thereby allowing the electrical signals to be applied individually to the feedback waveguide and the gain material layer. In specific implementations, the separation region may be a linear groove located between the first and second electrodes. Indeed, in some cases, the separation region may alternatively be a hole penetrating the electrode layer, as long as it can electrically separate the first and second electrodes. 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. The width of the separation region may be set based on actual requirements, as long as it can electrically separate the first and second electrodes. The size of the separation region is not limited herein.
[0014] In specific implementations, the first and second electrodes may be made of metallic material. In the manufacturing process, the first and second electrodes may be manufactured using the same processing process. Specifically, firstly, a metallic layer may be formed, and the region between the first and second electrodes, corresponding to the metallic layer, may be thinned or hollowed out by etching the metallic layer to obtain a separation region for separating the first and second electrodes.
[0015] In actual applications, a ground point may be provided within the laser, and the first electrode may form a path to the ground point and supply a current signal to the feedback waveguide, and the second electrode may form a path to the ground point and supply a current signal to the gain material layer. In the operation process of the laser, the current applied to the first electrode may differ 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 exceed 100 mA. The current values of the first and second electrodes may be set based on actual requirements. This is not limited herein.
[0016] In possible implementations, the laser in this embodiment of the present application may further include a diffraction grating structure. This diffraction grating structure may be placed on the sidewall of the gain-domain waveguide. The diffraction grating structure may be configured to perform mode selection on light propagated within the gain-domain waveguide. A resonance effect on the light is obtained by selecting the wavelength using the diffraction effect of the diffraction grating structure.
[0017] In the operation process of a laser, the gain material layer, under control by an electrical signal, can emit light within a specific spectral range, and its spectral range is 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 play a role in light transmission. Light emitted from the gain material layer is guided into the gain region waveguide. The light in the gain region waveguide passes through the feedback waveguide and is then guided to a second end face. The second end face can reflect its light to the feedback waveguide, thereby guiding the reflected light, after passing through the feedback waveguide and the gain region waveguide, to the first end face. The first end face has a reflective function and can reflect its light to the gain region waveguide. Therefore, the light is reflected back and forth between the first and second end faces, forming a resonance. In the process of light propagating between the first and second end faces, the diffraction grating structure can perform mode selection on the light propagated within the gain-region waveguide, and the feedback waveguide can adjust the phase of the light propagated within the feedback waveguide. Under the action of the diffraction grating structure and the feedback waveguide, the linewidth of the light can be narrowed to obtain a laser beam with a narrow linewidth. Furthermore, the first end face has a transmitting function, and the obtained laser beam with a narrow linewidth can be emitted through the first end face.
[0018] In possible implementations, the first end face may include an anti-reflective coating, thereby giving the first end face both reflective and transmitting functions. For example, the transmittance of the first end face may be about 90%, and the transmittance of the first end face R1 may be set based on actual requirements. This is not limited herein. The second end face may include a high-reflectance coating. For example, the reflectance of the second end face R2 may be about 90%, and the reflectance of the second end face R2 may be set based on actual requirements. This is not limited herein. In this way, light is reflected back and forth within a gain region waveguide and a feedback waveguide located between the first and second end faces, and the formed laser light can be emitted through the first end face.
[0019] Furthermore, the laser in this embodiment of the present application includes a gain region waveguide and a feedback waveguide. of side among , separated from the substrate did The electrode layer may further include a protective layer positioned on the side, and the protective layer of side among , separated from the substrate did It can be placed on the side. By placing a protective layer, the gain region waveguide, feedback waveguide, and diffraction grating structure can be protected, preventing damage to the gain region waveguide, feedback waveguide, and diffraction grating structure by subsequent manufacturing processes.
[0020] In some embodiments of this application, the length of the diffraction grating structure may match the length of the gain-domain waveguide. In this way, the mode-selective effect of the diffraction grating structure may be improved. In possible implementations, the diffraction grating structure is the gain-domain waveguide. of side among , separated from the substrate did It can be placed on the side. In the manufacturing process, after the gain-domain waveguide and the feedback waveguide are formed on the substrate, the diffraction grating structure can be formed on the gain-domain waveguide. In this way, the gain-domain waveguide can be manufactured on a flat surface. Indeed, in some cases, the diffraction grating structure is on the gain-domain waveguide. of side among It may be placed on the side closer to the substrate, or the diffraction grating structure may be a gain region waveguide. of side among , the side close to the substrate and the gain region waveguide of side among , spaced apart from the substrate did It may be arranged on both sides. This is not limited in this specification.
[0021] In a possible implementation, the diffraction grating structure may include a first adjustment region and a phase shift adjustment region. The grating constant of the phase shift adjustment region exceeds the grating constant of the first adjustment region. The phase shift adjustment region having a relatively large grating constant is provided to adjust the optical field distribution in the laser, whereby the optical field distribution becomes flatter, the spatial hole burning effect is reduced, and thereby the yield of the laser is improved. After the feedback waveguide is arranged in the laser, the energy of the laser may shift to the side close to the feedback waveguide. In the present embodiment of the present application, the center point of the phase shift adjustment region is the central position of the diffraction grating structure of side among , and may be arranged on the side close to the feedback waveguide. In this way, the phase shift adjustment region is close to the position where energy is concentrated in the laser, whereby the optical field distribution becomes flatter and the spatial hole burning effect is more effectively prevented.
[0022] In a possible implementation, the diffraction grating structure may be divided into two regions, namely, a first adjustment region and a phase shift adjustment region. In another possible implementation, the diffraction grating structure may alternatively be divided into three regions. In addition to the first adjustment region and the phase shift adjustment region, the diffraction grating structure may further include a second adjustment region. The phase shift adjustment region may be arranged between the first adjustment region and the second adjustment region, and the grating constant of the phase shift adjustment region exceeds the grating constant of the second adjustment region. In a specific implementation, the specific structure of the diffraction grating structure may be set based on actual requirements. This is not limited in this specification.
[0023] In a possible implementation, the length of the phase shift adjustment region can be any value (including the end point values) between 25% and 30% of the length of the diffraction grating structure. Specifically, the length of the phase shift adjustment region can be 25% or more of the length of the diffraction grating structure, and the length of the phase shift adjustment region can 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 can meet the requirements 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 diffraction grating structure of end among , the end close to the first end face is used as 0, and the diffraction grating structure of end among , the end close to the second end face is used as 1. The center point of the phase shift adjustment region can be arranged at a position that is 0.7 to 0.8 (including the end point values) of the length of the diffraction grating structure. In this way, the position of the phase shift adjustment region can be better adapted to the position where the energy is concentrated in the laser, and the spatial hole burning effect can be more effectively suppressed.
[0025] In a second embodiment, one 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. Since a feedback waveguide connected to a gain-domain waveguide is located within the laser, the linewidth of the laser emitted by the laser is narrowed. Therefore, the optical signal transmission effect of the optical module including the laser is improved. The optical module in this embodiment of the present application may further include a silicon optical modulator. The first end face of the laser is connected to the silicon optical modulator. In practical application, a set current may be applied to the laser so that the laser outputs a constant optical intensity. The internal refractive index of the silicon optical modulator is adjusted so that the laser light emitted by the laser interferes with each other. The coherence increase and coherence decrease of the light are used to represent 0 or 1, thereby carrying out the transmission of an optical signal.
[0026] In a third aspect, one embodiment of the present application further provides an apparatus which may include any of the lasers described above. Since a feedback waveguide connected to a gain-domain waveguide is located within the laser, the linewidth of the laser emitted by the laser is narrowed. As a result, the performance of the apparatus including this laser is also improved.
[0027] In possible implementations, 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 any device in a future-oriented advanced system (such as a 6G mobile communication system). Alternatively, the device may be any device in an open radio access network (ORAN) or a cloud radio access network (CRAN). Alternatively, the device may be any device in a communication system integrating two or more of the above-mentioned systems.
[0028] Alternatively, this device may be called an access network device, RAN entity, access node, or similar, and forms part of a communication system to help terminals perform wireless access. In possible scenarios, this device may be a base station, evolved nodeB (eNodeB), access point (AP), transmission reception point (TRP), next generation nodeB (gNB), next generation nodeB in a 6th generation (6G) mobile communication system, base station in a future mobile communication system, access node in a Wi-Fi system, or similar. This device may be a macro base station, micro base station, indoor base station, relay node, donor node, or wireless controller in a CRAN scenario. Optionally, this device may also be a server, wearable device, vehicle, in-vehicle equipment, or similar. For example, an access network device in vehicle-to-everything (V2X) technology may be a roadside unit (RSU).
[0029] In other possible scenarios, the device may consist of a central unit (CU), a distributed unit (DU), a CU control plane (CP), a CU user plane (UP), a radio unit (RU), or similar components. 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 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, 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 the ORAN system, CU may alternatively be called 0-CU (i.e., open CU), DU may alternatively be called 0-DU, CU-CP may alternatively be called 0-CU-CP, CU-UP may alternatively be called 0-CU-UP, and RU may alternatively be called 0-RU. For ease of explanation, this application uses CU, CU-CP, CU-UP, DU, and RU as examples. Any one of CU (or CU-CP or CU-UP), DU, and RU in this application may be implemented using a software module, a hardware module, or a combination thereof.
[0031] In specific implementations, the apparatus in this embodiment of the application may be replaced by another apparatus including a laser. The type of apparatus in this embodiment of the application is not limited herein.
[0032] In some implementations of this application, the apparatus may further include an optical module, the optical module including a laser. In other words, the laser may be integrated into the optical module. In specific implementations, the laser may alternatively be located in another component of the apparatus. For example, the laser may be located in a baseband processing unit (building baseband unit, BBU). Optionally, the laser may be directly integrated into the baseband board of the BBU.
[0033] In some embodiments of this application, the laser may be located on the circuit board of the device. For example, the laser may be directly integrated onto the circuit board, or it may be plugged into the circuit board, or it may be arranged according to the actual requirements. In this way, the cost of the optical module is reduced and the size of the device is reduced. [Brief explanation of the drawing]
[0034] [Figure 1] This figure shows the structure of a laser according to an embodiment of this application. [Figure 2] (1) and (2) are distribution diagrams showing the internal light field of the laser, respectively. [Figure 3] This figure shows the configuration of a diffraction grating structure according to an embodiment of this application. [Figure 4] This figure shows another configuration of the diffraction grating structure according to an embodiment of this application. [Figure 5] This figure shows the position of the phase shift adjustment region according to an embodiment of this application. [Figure 6] This figure shows another position of the phase shift adjustment region according to an embodiment of this application. [Figure 7] This figure shows the configuration of a DFB laser according to an embodiment of this application. [Modes for carrying out the invention]
[0035] To further clarify the purpose, technical solution, and advantages of this application, the application will be described in more detail below with reference to the accompanying drawings. The reference numerals in the accompanying drawings in the embodiments of this application are as follows (see the column "Explanation of Reference Numerals").
[0036] It should be noted that in the drawings attached to this application, the same reference numerals represent the same or similar configurations. Therefore, redundant descriptions are omitted. The representations of position and orientation in this application are explained using the attached drawings as examples. However, modifications may be made as necessary, and all such modifications are included within the scope of protection of this application. The attached drawings in this application are used solely to illustrate relative positional relationships and do not represent actual scale.
[0037] Optical communication technology can also be applied to wireless scenarios. Optical communication technology has high demands on laser linewidth. For example, based on the quadrature amplitude modulation (QAM16) method, which is the mainstream modulation method in current communication technology, the laser linewidth must be less than 5 megahertz (MHz), and the higher the modulation frequency, the higher the linewidth requirement. Furthermore, narrower linewidths help reduce the power consumption of optical digital signal processing (oDSP). However, current lasers have difficulty meeting the linewidth requirements of optical communication technology.
[0038] Based on this, embodiments of the present application provide a laser, an optical module, and an apparatus for narrowing the laser linewidth. The laser in embodiments of the present application can be of various types. For example, the laser may be a distribution feedback laser (DFB). The laser can be applied to optical communication scenarios, for example, to wireless short-range optical communication scenarios. The linewidth of the laser in embodiments of the present application can be less than 1 MHz and can meet the wireless transmission requirements for a transmission distance of about 10 kilometers (km).
[0039] Figure 1 shows the structure of a laser according to one embodiment of the present application. As shown in Figure 1, the laser provided in one embodiment of the present application may include a gain-domain waveguide 11, a feedback waveguide 12, a first end face R1, and a second end face R2. The gain-domain waveguide 11 and the feedback waveguide 12 are arranged between the first end face R1 and the second end face R2, and the end of the gain-domain waveguide 11 is connected to the end of the feedback waveguide 12, and the feedback waveguide 12 is connected to the gain-domain waveguide 11 of side among It is located on the side adjacent to the second end face R2. In Figure 1, the dashed line W is located between the gain region waveguide 11 and the feedback waveguide 12, specifically the gain region waveguide 11 is located on the side adjacent to the dashed line W. of side among The return waveguide 12 is located on the side adjacent to the first end face R1, and is represented by the dashed line W. of side among It is positioned on the side adjacent 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 application may be a distributed feedback laser. In specific implementations, the laser in this embodiment of the application may be replaced by other types of lasers, but this is not limited herein.
[0041] In this embodiment of the present application, both the gain-domain waveguide 11 and the feedback waveguide 12 are waveguides having optical transmission capabilities. Light in the gain-domain waveguide 11 is guided to a second end face R2 after passing through the feedback waveguide 12. The second end face R2 can reflect the light back to the feedback waveguide 12, thereby guiding the reflected light to a first end face R1 after passing through the feedback waveguide 12 and the gain-domain waveguide 11. The first end face R1 has a reflective function and can reflect the light back to the gain-domain 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. Furthermore, the first end face R1 has a transmitting function, and the acquired laser light with a narrow linewidth can be emitted through the first end face R1.
[0042] In the laser provided in this embodiment of the present application, a feedback waveguide is arranged connected to the gain region waveguide, thereby increasing the equivalent resonator length of the laser, reducing the laser's resonant cavity loss and threshold gain, and compressing the laser's linewidth. Furthermore, the feedback waveguide is monolithically integrated inside the laser, eliminating the need to place an external resonator outside the laser's resonator. This improves the integration density of the laser and reduces 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-domain waveguide, and the other factor is the optical path length of the light outside the gain-domain waveguide. The second end face has a reflective function, and when light in the feedback waveguide reaches the second end face, it is reflected back. Feedback light may refer to the light reflected by the second end face that propagates through the feedback waveguide to the gain-domain waveguide and returns. 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 possible implementations, the gain-domain waveguide 11 may contain indium gallium arsenide phosphide (InGaAsP) material, and the feedback waveguide 12 may contain indium gallium arsenide phosphide (InGaAsP) material. Indeed, the gain-domain waveguide 11 and the feedback waveguide 12 may alternatively contain other materials. This is not limited herein. Both the gain-domain waveguide 11 and the feedback waveguide 12 may be impregnated with impurities of a specific material, resulting in different doping concentrations for the gain-domain waveguide 11 and the feedback waveguide 12, thereby giving them different refractive indices. Furthermore, the gain-domain waveguide 11 and the feedback waveguide 12 may be arranged in a linear configuration to exhibit good optical transmission functionality.
[0045] In specific implementations, the thickness of the gain-domain waveguide may be 2 micrometers (μm) or less, and the thickness of the feedback waveguide may also be 2 μm or less. In this way, the thicknesses of the gain-domain waveguide and the feedback waveguide are equivalent to the wavelength of light, and as a result, the light within the gain-domain waveguide and the feedback waveguide satisfies the wave optical transmission law, and the light can propagate inside the gain-domain waveguide and the feedback waveguide.
[0046] In possible implementations, the laser provided in these embodiments of the present application may further include a substrate 10. The substrate 10 is configured to support a gain-domain waveguide 11 and a feedback waveguide 12, thereby allowing the gain-domain waveguide 11 and the feedback waveguide 12 to be integrated onto the same substrate 10. Optionally, the substrate 10 may include an indium phosphate material, an indium gallium arsenide aluminum material, or an indium gallium aluminum arsenide material. Indeed, the substrate 10 may, alternatively, include other materials. This is not limited herein.
[0047] Referring further to Figure 1, the laser in this embodiment of the present application may further include a gain material layer 101. The gain material layer 101 is placed between the substrate 10 and the gain region waveguide 11, and the gain material layer 101 may be configured to emit light under control by an electrical signal. In specific implementations, the gain material layer 10 may be placed in a region corresponding to the gain region waveguide 11. For example, as shown in Figure 1, the gain material layer 10 is located along the dashed line W of side among It may be positioned on the side adjacent to the first end face R1. In this way, light emitted from the gain material layer 101 can be guided to the gain region waveguide 11. A passive material is used between the feedback waveguide 12 and the substrate 10, and since this passive material does not emit light under control by an electrical signal, it avoids the effect of spontaneous emission on the linewidth expansion of the laser.
[0048] In some embodiments of this application, the feedback waveguide 12 may be configured to adjust the phase of light propagated within the feedback waveguide 12 under control by an electrical signal. The refractive index of the feedback waveguide 12 can be adjusted by applying an electrical signal to the feedback waveguide 12 to adjust the phase of light propagated within the feedback waveguide 12, thereby enabling single-longitudinal-mode laser oscillation of the laser. Furthermore, the laser may include a first electrode 15. The first electrode 15 is positioned corresponding to the feedback waveguide 12 and may be configured to supply an electrical signal to the feedback waveguide 12.
[0049] As shown in Figure 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 may be positioned corresponding to a feedback waveguide 12 and configured to supply an electrical signal to the feedback waveguide 12. The second electrode 16 may be positioned corresponding to a gain region waveguide 11 and configured to supply an electrical signal to the laser's gain material layer 101.
[0050] The first electrode 15 and the second electrode 16 are separated by a separation region 17, which allows for the separation of the electrical signals between the first electrode 15 and the second electrode 16, thereby allowing the electrical signals to be applied separately to the feedback waveguide 12 and the gain material layer 101. In specific implementations, the separation region 17 may be a track-like 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 it 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 it can electrically separate the first electrode 15 and the second electrode 16. The size of the isolation region 17 is not limited herein.
[0051] In specific implementations, the first electrode 15 and the second electrode 16 may be made of metallic material. In the manufacturing process, the first electrode 15 and the second electrode 16 may be manufactured using the same processing process. Specifically, firstly, a metallic layer may be formed, and the region between the first electrode 15 and the second electrode 16, corresponding to the metallic layer, may be thinned or hollowed out by etching the metallic layer to obtain a separation region for separating the first electrode and the second electrode.
[0052] In actual applications, a ground point may be provided in the laser, and the first electrode 15 forms a path to the ground point and supplies a current signal to the feedback waveguide 12, and the second electrode 16 forms a path to the ground point and supplies 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 differ 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 exceed 100 mA. The current values of the first electrode 15 and the second electrode 16 may be set based on actual requirements. This is not limited herein.
[0053] In possible implementations, the laser in this embodiment of the present application may further include a diffraction grating structure 13. The diffraction grating structure 13 may be positioned on the sidewall of the gain-domain waveguide 11. The diffraction grating structure 13 may be configured to perform mode selection on light propagated within the gain-domain waveguide 11. By utilizing the diffraction effect of the diffraction grating structure 13 to select wavelengths, a resonance effect on the light is obtained.
[0054] In the laser's operation process, the gain material layer 101 can emit light within a specific spectral range under electrical signal control, and its spectral range is broadened. The gain region waveguide 11 and the feedback waveguide 12 do not emit light under electrical signal control. Therefore, the gain region waveguide 11 and the feedback waveguide 12 can play a role in light transmission. 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 its light back to the feedback waveguide 12, thereby guiding the reflected light, after passing through the feedback waveguide 12 and the gain region waveguide 11, to the first end face R1. The first end face R1 has a reflective function and can reflect its light back to the gain region waveguide 11. Therefore, 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 propagated within the gain region waveguide 11, and the feedback waveguide 12 can adjust the phase of the light propagated within 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 emitted through the first end face R1.
[0055] In possible implementations, the first end face R1 may include an anti-reflective coating, thereby giving the first end face R1 both reflective and transmitting functions. For example, the transmittance of the first end face R1 may be about 90% and may be set based on actual requirements. This is not limited herein. The second end face R2 may include a high-reflectance coating. For example, the reflectance of the second end face R2 may be about 90% and may be set based on actual requirements. This is not limited herein. In this way, light is reflected back and forth within the gain region waveguide 11 and the feedback waveguide 12 located 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] Furthermore, the laser in this embodiment of the present application is a gain region waveguide 11 and a feedback waveguide 12 substrate 10 of side among , separated from substrate 10 did The electrode layer may further comprise a protective layer 14 positioned on the side, and the electrode layer is provided with the protective layer 14 of side among , separated from substrate 10 did It can be placed on the side. By placing the protective layer 14, the gain region waveguide 11, the feedback waveguide 12, and the diffraction grating structure 13 can be protected, preventing damage to the gain region waveguide 11, the feedback waveguide 12, and the diffraction grating structure 13 by subsequent manufacturing processes.
[0057] Referring further to Figure 1, in some embodiments of this application, the length of the diffraction grating structure 13 may match the length of the gain-domain waveguide 11. In this way, the mode-selection effect of the diffraction grating structure 13 may be improved. In possible implementations, the diffraction grating structure 13 is located in the gain-domain waveguide 11 of side among , separated from substrate 10 did It can be placed on the side. In the manufacturing process, after the gain region waveguide 11 and the feedback waveguide 12 are formed on the substrate 10, the diffraction 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 diffraction grating structure 13 can be alternatively placed on the gain region waveguide 11 of side among The diffraction grating structure 13 may be positioned on the side closer to the substrate 10, or the gain region waveguide 11 of side among , the side adjacent to the substrate 10, and the gain region waveguide 11 of side among , separated from substrate 10 did They may be placed on both sides. This is not limited to this specification.
[0058] Figure 2 is a distribution diagram showing the internal optical field of a laser. Figure 2(1) is a distribution diagram showing the optical field of a laser without a feedback waveguide. Figure 2(2) is a distribution diagram showing the optical field of a laser with a feedback waveguide. In Figures 2(1) and (2), the horizontal axis represents the position from the first end face to the second end face inside the laser, and a larger value in the horizontal coordinate indicates that the position is closer to the second end face. The vertical axis represents the energy density at various positions inside the laser. As shown in Figure 2(1), in a laser without a feedback waveguide, the energy is mainly concentrated at the central position of the laser. As shown in Figure 2(2), in the embodiment of this application, after a feedback waveguide is placed inside the laser, the energy is mainly concentrated at the central position on the right side of the laser (the side closer to the second end face). That is, the energy of the laser shifts to the side closer to the feedback waveguide.
[0059] As can be seen from Figure 2, the energy within the laser is mainly concentrated at one location, resulting in relatively large light consumption at the energy-concentrated location. 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. Yield can refer to the proportion of lasers in a batch that meet the requirements. To suppress the spatial hole burning effect of the laser, the embodiments of this application modify a specific structure of the diffraction grating. Details are as follows.
[0060] Figure 3 shows the configuration of a diffraction grating structure according to one embodiment of the present application. As shown in Figure 3, the diffraction grating structure 13 may include a first adjustment region Q1 and a phase shift adjustment region P. The grating constant of the phase shift adjustment region P exceeds the grating constant of the first adjustment region Q1. The phase shift adjustment region P, having a relatively large grating constant, is provided to adjust the optical field distribution within the laser, thereby flattening the optical field distribution, reducing the spatial hole burning effect, and thereby improving the laser yield. After a feedback waveguide is placed within the laser, the laser energy may be shifted toward the side closer to the feedback waveguide. In this embodiment of the present application, the center point of the phase shift adjustment region P is the central position of the diffraction grating structure 13. of side among It can be positioned on the side adjacent to the return waveguide. In this way, the phase shift adjustment region P is close to the location where energy is concentrated in the laser, thereby making the optical field distribution flatter and the spatial hole burning effect more effectively prevented.
[0061] In possible implementations, the diffraction grating structure 13 may be divided into two regions, namely, a first adjustment region Q1 and a phase shift adjustment region P. Figure 4 shows another configuration of the diffraction grating structure according to one embodiment of the present invention. As shown in Figure 4, in another possible implementation, the diffraction grating structure 13 may 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 may further include a second adjustment region Q2. The phase shift adjustment region P may be located between the first adjustment region Q1 and the second adjustment region Q2, and the lattice constant of the phase shift adjustment region P exceeds the lattice constant of the second adjustment region Q2. In specific implementations, the specific structure of the diffraction grating structure 13 may be determined based on actual requirements. This is not limited to the present specification.
[0062] In possible implementations, the length of the phase shift adjustment region P can be any value (including endpoint values) between 25% and 30% of the length of the diffraction grating structure 13. Specifically, the length of the phase shift adjustment region P can be 25% or more of the length of the diffraction grating structure 13, and 30% or less of the length of the diffraction grating structure 13. For example, the length of the diffraction grating structure 13 may be approximately 1000 μm, and the length of the phase shift adjustment region P may be approximately 300 μm. In this way, the length of the phase shift adjustment region P can satisfy the requirements for adjusting the optical field distribution of the laser.
[0063] Figure 5 shows the position of the phase shift adjustment region according to one embodiment of the present application. Figure 6 shows another position of the phase shift adjustment region according to one embodiment of the present application. Referring to Figures 5 and 6, the length of the diffraction grating structure 13 is normalized, and the diffraction grating structure 13 of end among The end adjacent to the first end face R1 is used as 0, and the diffraction grating structure 13 of end among The end adjacent to the second end face (i.e., the position of the dashed line W) is used as 1. The center point of the phase shift adjustment region P is positioned at a location 0.7 to 0.8 (including the end point value) of the length of the diffraction grating structure 13. In this way, the position of the phase shift adjustment region P can be better matched to the location where energy is concentrated in the laser, and the spatial hole burning effect can be suppressed more effectively. For example, in Figure 5, the center point of the phase shift adjustment region P is positioned at a location 0.7 of the length of the diffraction grating structure 13. An example where the length of the diffraction grating structure 13 is approximately 1000 μm is still used. The phase shift adjustment region P can be positioned at a location 550 μm to 850 μm of the length of the diffraction grating structure 13. As another example, in Figure 6, the center point of the phase shift adjustment region P is positioned at a location 0.8 of the length of the diffraction grating structure 13. An example where the length of the diffraction grating structure 13 is approximately 1000 μm is still used. The phase shift adjustment region P can be positioned at a location between 650 μm and 950 μm in length of the diffraction grating structure 13.
[0064] In the laser provided in this embodiment of the present application, a feedback waveguide is provided, thereby increasing the equivalent resonator length of the laser and compressing the laser linewidth. Furthermore, the feedback waveguide is integrated inside the laser, eliminating the need to place an external resonator outside the laser's resonator. This improves the integration density of the laser, reduces the laser's volume, and lowers both the material and processing costs of the laser.
[0065] Figure 7 shows the structure of a DFB laser according to an embodiment of this application. As shown in Figure 7, the DFB laser in this embodiment of this application is a laser diode ( laser diod, LD ), may include structures such as a rear mirror, diffraction grating region and gain region, front mirror, isolator, coupling prism, and thermoelectric cooler (TEC). The DFB laser in this embodiment of the application has a simple structure and a small volume.
[0066] Based on a similar technical concept, one 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. Since a feedback waveguide connected to a gain-domain waveguide is located within the laser, the linewidth of the laser emitted by the laser is narrowed. Therefore, the optical signal transmission effect of the optical module including the laser is improved. Furthermore, the optical module in this embodiment of the present application may include a silicon optical modulator. The first end face of the laser is connected to the silicon optical modulator. In practical application, a set current may be applied to the laser so that the laser outputs a constant optical intensity. The internal refractive index of the silicon optical modulator is adjusted so that the laser light emitted by the laser interferes with each other. The coherence increase and coherence decrease of the light are used to represent 0 or 1, thereby carrying out the transmission of an optical signal.
[0067] Based on a similar technical concept, one embodiment of this application further provides an apparatus that may include any of the lasers described above. Because a feedback waveguide connected to a gain-domain waveguide is located within the laser, the linewidth of the laser emitted by the laser is narrowed. As a result, the performance of the apparatus including the laser is also improved.
[0068] In possible implementations, 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 any device in a future-oriented advanced system (such as a 6G mobile communication system). Alternatively, the device may be any device in an open radio access network (ORAN) or a cloud radio access network (CRAN). Alternatively, the device may be any device in a communication system integrating two or more of the above-mentioned systems.
[0069] Alternatively, this device may be called an access network device, RAN entity, access node, or similar, and forms part of a communication system to help terminals perform wireless access. In possible scenarios, this device may be a base station, evolved nodeB (eNodeB), access point (AP), transmission reception point (TRP), next generation nodeB (gNB), next generation nodeB in a 6th generation (6G) mobile communication system, base station in a future mobile communication system, access node in a Wi-Fi system, or similar. This device may be a macro base station, micro base station, indoor base station, relay node, donor node, or wireless controller in a CRAN scenario. Optionally, this device may also be a server, wearable device, vehicle, in-vehicle equipment, or similar. For example, an access network device in vehicle-to-everything (V2X) technology may be a roadside unit (RSU).
[0070] In other possible scenarios, the device may consist of a central unit (CU), a distributed unit (DU), a CU control plane (CP), a CU user plane (UP), a radio unit (RU), or similar components. 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, 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 the ORAN system, CU may alternatively be called 0-CU (i.e., open CU), DU may alternatively be called 0-DU, CU-CP may alternatively be called 0-CU-CP, CU-UP may alternatively be called 0-CU-UP, and RU may alternatively be called 0-RU. For ease of explanation, this application uses CU, CU-CP, CU-UP, DU, and RU as examples. Any one of CU (or CU-CP or CU-UP), DU, and RU in this application may be implemented using a software module, a hardware module, or a combination thereof.
[0072] In specific implementations, the apparatus in this embodiment of the application may be replaced by another apparatus including a laser. The type of apparatus in this embodiment of the application is not limited herein.
[0073] In some embodiments of this application, the apparatus may further include an optical module, the optical module including a laser. In other words, the laser may be integrated into the optical module. In specific implementations, the laser may alternatively be located in another component of the apparatus. For example, the laser may be located in a building baseband unit (BBU). Optionally, the laser may be directly integrated into the baseband board of the BBU.
[0074] In some embodiments of this application, the laser may be located on the circuit board of the device. For example, the laser may be directly integrated onto the circuit board, or it may be plugged into the circuit board, or it may be arranged according to the actual requirements. In this way, the cost of the optical module is reduced and the size of the device is reduced.
[0075] While exemplary embodiments of this application are described, those skilled in the art may modify and alter these embodiments after understanding the basic concepts of the invention. Therefore, the following claims are intended to be construed to encompass preferred embodiments and all changes and modifications included within the scope of this application.
[0076] Clearly, those skilled in the art can make various modifications and variations to the embodiments of this application without departing from the spirit and scope of the embodiments. In this case, this application is intended to cover such modifications and variations to the embodiments of this application, insofar as they fall within the scope of protection defined by the following claims and their equivalents in the art. [Explanation of symbols]
[0077] 10 circuit boards 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 Region Q1 First adjustment area Q2 Second adjustment area
Claims
1. A laser comprising a gain region waveguide, a feedback waveguide, a first end face, a second end face, an electrode layer, and a diffraction grating structure, The gain region waveguide and the feedback waveguide are arranged between the first end face and the second end face, the end of the gain region waveguide is connected to the end of the feedback waveguide, and the feedback waveguide is arranged on the side of the gain region waveguide that is closer to the second end face. The first end face and the second end face are configured to transmit light into the gain region waveguide and the feedback waveguide, and the first end face is configured to transmit laser light. The electrode layer includes a first electrode, a second electrode, and a separation region, the separation region being configured to separate the first electrode from the second electrode, the first electrode being positioned in a location corresponding to the feedback waveguide and configured to supply an electrical signal to the feedback waveguide, the second electrode being positioned in a location corresponding to the gain region waveguide and configured to supply an electrical signal to the laser gain material layer. The diffraction grating structure is positioned on the side wall of the gain-region waveguide adjacent to the second electrode, and the diffraction grating structure is configured to perform mode selection on light propagated within the gain-region waveguide. The diffraction grating structure includes a first adjustment region and a phase shift adjustment region, wherein the grating constant of the phase shift adjustment region exceeds the grating constant of the first adjustment region, and the center point of the phase shift adjustment region is located on the side of the central position of the diffraction grating structure that is close to the feedback waveguide. The length of the diffraction grating structure is normalized, the end of the diffraction grating structure closest to the first end face is used as 0, the end of the diffraction grating structure closest to the second end face is used as 1, and the center point of the phase shift adjustment region is positioned at a position that is 0.7 to 0.8 of the length of the diffraction grating structure. Laser.
2. The laser according to claim 1, wherein the feedback waveguide is configured to adjust the phase of light propagated within the feedback waveguide under control by an electrical signal.
3. The laser according to claim 1, wherein the depth of the separation region is 0.5 micrometers to 0.8 micrometers.
4. The laser according to claim 1, wherein the length of the phase shift adjustment region is 25% to 30% of the length of the diffraction grating structure.
5. The laser according to claim 1, wherein the length of the diffraction grating structure is the same as the length of the gain region waveguide.
6. Further equipped with a circuit board, The substrate is configured to support the gain region waveguide and the feedback waveguide. The diffraction grating structure is positioned on the side of the gain region waveguide that is spaced away from the substrate. The laser according to claim 1.
7. The aforementioned gain material layer further comprises, The gain material layer is disposed between the substrate and the gain region waveguide, and the gain material layer is configured to emit light under control by an electrical signal. The laser according to claim 6.
8. The laser according to claim 1, wherein the thickness of the gain region waveguide is 2 micrometers or less, and the thickness of the feedback waveguide is 2 micrometers or less.
9. The laser according to claim 1, wherein the first end face includes an anti-reflective coating, and the second end face includes a high-reflectivity coating.
10. The laser according to claim 1, wherein the laser is a distributed feedback type laser.
11. An optical module comprising the laser described in any one of claims 1 to 10.
12. The optical module according to claim 11, further comprising a silicon optical modulator, wherein the first end face of the laser is connected to the silicon optical modulator.
13. An apparatus comprising the laser described in any one of claims 1 to 10.
14. The apparatus according to claim 13, wherein the apparatus is a wireless unit or a distributed unit.
15. Equipped with an additional optical module, The optical module includes the laser, The apparatus according to claim 13.